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4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
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12 | <body> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
15 | <h3 id="TOP">Index</h3> |
15 | <h3 id="TOP">Index</h3> |
16 | |
16 | |
17 | <ul><li><a href="#NAME">NAME</a></li> |
17 | <ul><li><a href="#NAME">NAME</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
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19 | <li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
24 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
25 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
26 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
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27 | <ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
28 | <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | </ul> |
29 | </ul> |
28 | </li> |
30 | </li> |
29 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
31 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> |
32 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a> |
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33 | <ul><li><a href="#The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</a></li> |
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34 | <li><a href="#Watcher_Specific_Functions">Watcher-Specific Functions</a></li> |
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35 | </ul> |
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36 | </li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
37 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a> |
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38 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</a></li> |
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39 | </ul> |
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40 | </li> |
32 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> |
41 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a> |
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42 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</a></li> |
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43 | </ul> |
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44 | </li> |
33 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
45 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a> |
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46 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</a></li> |
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47 | </ul> |
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48 | </li> |
34 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
49 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a> |
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50 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</a></li> |
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51 | </ul> |
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52 | </li> |
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53 | <li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a> |
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54 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</a></li> |
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55 | </ul> |
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56 | </li> |
35 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
57 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a> |
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58 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</a></li> |
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59 | </ul> |
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60 | </li> |
36 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
61 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a> |
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62 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</a></li> |
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63 | </ul> |
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64 | </li> |
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65 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a> |
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66 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</a></li> |
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67 | </ul> |
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68 | </li> |
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69 | <li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a> |
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70 | <ul><li><a href="#Watcher_Specific_Functions_and_Data_-10">Watcher-Specific Functions and Data Members</a></li> |
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71 | </ul> |
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72 | </li> |
37 | </ul> |
73 | </ul> |
38 | </li> |
74 | </li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
75 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
76 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
77 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
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78 | <li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li> |
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79 | <li><a href="#EMBEDDING">EMBEDDING</a> |
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80 | <ul><li><a href="#FILESETS">FILESETS</a> |
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81 | <ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li> |
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82 | <li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> |
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83 | <li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> |
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84 | </ul> |
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85 | </li> |
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86 | <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> |
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87 | <li><a href="#EXAMPLES">EXAMPLES</a></li> |
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88 | </ul> |
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89 | </li> |
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90 | <li><a href="#COMPLEXITIES">COMPLEXITIES</a></li> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
91 | <li><a href="#AUTHOR">AUTHOR</a> |
43 | </li> |
92 | </li> |
44 | </ul><hr /> |
93 | </ul><hr /> |
45 | <!-- INDEX END --> |
94 | <!-- INDEX END --> |
46 | |
95 | |
47 | <h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> |
96 | <h1 id="NAME">NAME</h1> |
48 | <div id="NAME_CONTENT"> |
97 | <div id="NAME_CONTENT"> |
49 | <p>libev - a high performance full-featured event loop written in C</p> |
98 | <p>libev - a high performance full-featured event loop written in C</p> |
50 | |
99 | |
51 | </div> |
100 | </div> |
52 | <h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
101 | <h1 id="SYNOPSIS">SYNOPSIS</h1> |
53 | <div id="SYNOPSIS_CONTENT"> |
102 | <div id="SYNOPSIS_CONTENT"> |
54 | <pre> #include <ev.h> |
103 | <pre> #include <ev.h> |
55 | |
104 | |
56 | </pre> |
105 | </pre> |
57 | |
106 | |
58 | </div> |
107 | </div> |
59 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
108 | <h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1> |
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109 | <div id="EXAMPLE_PROGRAM_CONTENT"> |
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110 | <pre> #include <ev.h> |
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111 | |
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112 | ev_io stdin_watcher; |
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113 | ev_timer timeout_watcher; |
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114 | |
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115 | /* called when data readable on stdin */ |
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116 | static void |
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117 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
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118 | { |
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119 | /* puts ("stdin ready"); */ |
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120 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
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121 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
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122 | } |
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123 | |
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124 | static void |
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125 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
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126 | { |
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127 | /* puts ("timeout"); */ |
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128 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
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129 | } |
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130 | |
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131 | int |
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132 | main (void) |
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133 | { |
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134 | struct ev_loop *loop = ev_default_loop (0); |
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135 | |
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136 | /* initialise an io watcher, then start it */ |
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137 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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138 | ev_io_start (loop, &stdin_watcher); |
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139 | |
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140 | /* simple non-repeating 5.5 second timeout */ |
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141 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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142 | ev_timer_start (loop, &timeout_watcher); |
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143 | |
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144 | /* loop till timeout or data ready */ |
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145 | ev_loop (loop, 0); |
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146 | |
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147 | return 0; |
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148 | } |
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149 | |
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150 | </pre> |
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151 | |
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152 | </div> |
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153 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
60 | <div id="DESCRIPTION_CONTENT"> |
154 | <div id="DESCRIPTION_CONTENT"> |
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155 | <p>The newest version of this document is also available as a html-formatted |
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156 | web page you might find easier to navigate when reading it for the first |
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157 | time: <a href="http://cvs.schmorp.de/libev/ev.html">http://cvs.schmorp.de/libev/ev.html</a>.</p> |
61 | <p>Libev is an event loop: you register interest in certain events (such as a |
158 | <p>Libev is an event loop: you register interest in certain events (such as a |
62 | file descriptor being readable or a timeout occuring), and it will manage |
159 | file descriptor being readable or a timeout occuring), and it will manage |
63 | these event sources and provide your program with events.</p> |
160 | these event sources and provide your program with events.</p> |
64 | <p>To do this, it must take more or less complete control over your process |
161 | <p>To do this, it must take more or less complete control over your process |
65 | (or thread) by executing the <i>event loop</i> handler, and will then |
162 | (or thread) by executing the <i>event loop</i> handler, and will then |
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68 | watchers</i>, which are relatively small C structures you initialise with the |
165 | watchers</i>, which are relatively small C structures you initialise with the |
69 | details of the event, and then hand it over to libev by <i>starting</i> the |
166 | details of the event, and then hand it over to libev by <i>starting</i> the |
70 | watcher.</p> |
167 | watcher.</p> |
71 | |
168 | |
72 | </div> |
169 | </div> |
73 | <h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
170 | <h1 id="FEATURES">FEATURES</h1> |
74 | <div id="FEATURES_CONTENT"> |
171 | <div id="FEATURES_CONTENT"> |
75 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
172 | <p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the |
76 | kqueue mechanisms for file descriptor events, relative timers, absolute |
173 | BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms |
77 | timers with customised rescheduling, signal events, process status change |
174 | for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface |
78 | events (related to SIGCHLD), and event watchers dealing with the event |
175 | (for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers |
79 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
176 | with customised rescheduling (<code>ev_periodic</code>), synchronous signals |
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177 | (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event |
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178 | watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
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179 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
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180 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
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181 | (<code>ev_fork</code>).</p> |
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182 | <p>It also is quite fast (see this |
80 | fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing |
183 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
81 | it to libevent for example).</p> |
184 | for example).</p> |
82 | |
185 | |
83 | </div> |
186 | </div> |
84 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
187 | <h1 id="CONVENTIONS">CONVENTIONS</h1> |
85 | <div id="CONVENTIONS_CONTENT"> |
188 | <div id="CONVENTIONS_CONTENT"> |
86 | <p>Libev is very configurable. In this manual the default configuration |
189 | <p>Libev is very configurable. In this manual the default configuration will |
87 | will be described, which supports multiple event loops. For more info |
190 | be described, which supports multiple event loops. For more info about |
88 | about various configuration options please have a look at the file |
191 | various configuration options please have a look at <strong>EMBED</strong> section in |
89 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
192 | this manual. If libev was configured without support for multiple event |
90 | support for multiple event loops, then all functions taking an initial |
193 | loops, then all functions taking an initial argument of name <code>loop</code> |
91 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
194 | (which is always of type <code>struct ev_loop *</code>) will not have this argument.</p> |
92 | will not have this argument.</p> |
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93 | |
195 | |
94 | </div> |
196 | </div> |
95 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
197 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1> |
96 | <div id="TIME_REPRESENTATION_CONTENT"> |
198 | <div id="TIME_REPRESENTATION_CONTENT"> |
97 | <p>Libev represents time as a single floating point number, representing the |
199 | <p>Libev represents time as a single floating point number, representing the |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
200 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | the beginning of 1970, details are complicated, don't ask). This type is |
201 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
202 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
101 | to the double type in C.</p> |
203 | to the <code>double</code> type in C, and when you need to do any calculations on |
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204 | it, you should treat it as such.</p> |
102 | |
205 | |
103 | </div> |
206 | </div> |
104 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
207 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1> |
105 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
208 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
106 | <p>These functions can be called anytime, even before initialising the |
209 | <p>These functions can be called anytime, even before initialising the |
107 | library in any way.</p> |
210 | library in any way.</p> |
108 | <dl> |
211 | <dl> |
109 | <dt>ev_tstamp ev_time ()</dt> |
212 | <dt>ev_tstamp ev_time ()</dt> |
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113 | you actually want to know.</p> |
216 | you actually want to know.</p> |
114 | </dd> |
217 | </dd> |
115 | <dt>int ev_version_major ()</dt> |
218 | <dt>int ev_version_major ()</dt> |
116 | <dt>int ev_version_minor ()</dt> |
219 | <dt>int ev_version_minor ()</dt> |
117 | <dd> |
220 | <dd> |
118 | <p>You can find out the major and minor version numbers of the library |
221 | <p>You can find out the major and minor ABI version numbers of the library |
119 | you linked against by calling the functions <code>ev_version_major</code> and |
222 | you linked against by calling the functions <code>ev_version_major</code> and |
120 | <code>ev_version_minor</code>. If you want, you can compare against the global |
223 | <code>ev_version_minor</code>. If you want, you can compare against the global |
121 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
224 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
122 | version of the library your program was compiled against.</p> |
225 | version of the library your program was compiled against.</p> |
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226 | <p>These version numbers refer to the ABI version of the library, not the |
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227 | release version.</p> |
123 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
228 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
124 | as this indicates an incompatible change. Minor versions are usually |
229 | as this indicates an incompatible change. Minor versions are usually |
125 | compatible to older versions, so a larger minor version alone is usually |
230 | compatible to older versions, so a larger minor version alone is usually |
126 | not a problem.</p> |
231 | not a problem.</p> |
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232 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
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233 | version.</p> |
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234 | <pre> assert (("libev version mismatch", |
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235 | ev_version_major () == EV_VERSION_MAJOR |
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236 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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237 | |
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238 | </pre> |
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239 | </dd> |
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240 | <dt>unsigned int ev_supported_backends ()</dt> |
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241 | <dd> |
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242 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
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243 | value) compiled into this binary of libev (independent of their |
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244 | availability on the system you are running on). See <code>ev_default_loop</code> for |
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245 | a description of the set values.</p> |
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246 | <p>Example: make sure we have the epoll method, because yeah this is cool and |
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247 | a must have and can we have a torrent of it please!!!11</p> |
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248 | <pre> assert (("sorry, no epoll, no sex", |
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249 | ev_supported_backends () & EVBACKEND_EPOLL)); |
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250 | |
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251 | </pre> |
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252 | </dd> |
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253 | <dt>unsigned int ev_recommended_backends ()</dt> |
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254 | <dd> |
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255 | <p>Return the set of all backends compiled into this binary of libev and also |
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256 | recommended for this platform. This set is often smaller than the one |
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257 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
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258 | most BSDs and will not be autodetected unless you explicitly request it |
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259 | (assuming you know what you are doing). This is the set of backends that |
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260 | libev will probe for if you specify no backends explicitly.</p> |
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261 | </dd> |
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262 | <dt>unsigned int ev_embeddable_backends ()</dt> |
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263 | <dd> |
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264 | <p>Returns the set of backends that are embeddable in other event loops. This |
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265 | is the theoretical, all-platform, value. To find which backends |
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266 | might be supported on the current system, you would need to look at |
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267 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
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268 | recommended ones.</p> |
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269 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
127 | </dd> |
270 | </dd> |
128 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
271 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
129 | <dd> |
272 | <dd> |
130 | <p>Sets the allocation function to use (the prototype is similar to the |
273 | <p>Sets the allocation function to use (the prototype is similar - the |
131 | realloc C function, the semantics are identical). It is used to allocate |
274 | semantics is identical - to the realloc C function). It is used to |
132 | and free memory (no surprises here). If it returns zero when memory |
275 | allocate and free memory (no surprises here). If it returns zero when |
133 | needs to be allocated, the library might abort or take some potentially |
276 | memory needs to be allocated, the library might abort or take some |
134 | destructive action. The default is your system realloc function.</p> |
277 | potentially destructive action. The default is your system realloc |
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278 | function.</p> |
135 | <p>You could override this function in high-availability programs to, say, |
279 | <p>You could override this function in high-availability programs to, say, |
136 | free some memory if it cannot allocate memory, to use a special allocator, |
280 | free some memory if it cannot allocate memory, to use a special allocator, |
137 | or even to sleep a while and retry until some memory is available.</p> |
281 | or even to sleep a while and retry until some memory is available.</p> |
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282 | <p>Example: Replace the libev allocator with one that waits a bit and then |
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283 | retries).</p> |
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284 | <pre> static void * |
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285 | persistent_realloc (void *ptr, size_t size) |
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286 | { |
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287 | for (;;) |
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288 | { |
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289 | void *newptr = realloc (ptr, size); |
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290 | |
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291 | if (newptr) |
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292 | return newptr; |
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293 | |
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294 | sleep (60); |
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295 | } |
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296 | } |
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297 | |
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298 | ... |
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299 | ev_set_allocator (persistent_realloc); |
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300 | |
|
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301 | </pre> |
138 | </dd> |
302 | </dd> |
139 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
303 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
140 | <dd> |
304 | <dd> |
141 | <p>Set the callback function to call on a retryable syscall error (such |
305 | <p>Set the callback function to call on a retryable syscall error (such |
142 | as failed select, poll, epoll_wait). The message is a printable string |
306 | as failed select, poll, epoll_wait). The message is a printable string |
143 | indicating the system call or subsystem causing the problem. If this |
307 | indicating the system call or subsystem causing the problem. If this |
144 | callback is set, then libev will expect it to remedy the sitution, no |
308 | callback is set, then libev will expect it to remedy the sitution, no |
145 | matter what, when it returns. That is, libev will generally retry the |
309 | matter what, when it returns. That is, libev will generally retry the |
146 | requested operation, or, if the condition doesn't go away, do bad stuff |
310 | requested operation, or, if the condition doesn't go away, do bad stuff |
147 | (such as abort).</p> |
311 | (such as abort).</p> |
|
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312 | <p>Example: This is basically the same thing that libev does internally, too.</p> |
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313 | <pre> static void |
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314 | fatal_error (const char *msg) |
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315 | { |
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316 | perror (msg); |
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317 | abort (); |
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318 | } |
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319 | |
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320 | ... |
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321 | ev_set_syserr_cb (fatal_error); |
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322 | |
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323 | </pre> |
148 | </dd> |
324 | </dd> |
149 | </dl> |
325 | </dl> |
150 | |
326 | |
151 | </div> |
327 | </div> |
152 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
328 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1> |
153 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
329 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
154 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
330 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
155 | types of such loops, the <i>default</i> loop, which supports signals and child |
331 | types of such loops, the <i>default</i> loop, which supports signals and child |
156 | events, and dynamically created loops which do not.</p> |
332 | events, and dynamically created loops which do not.</p> |
157 | <p>If you use threads, a common model is to run the default event loop |
333 | <p>If you use threads, a common model is to run the default event loop |
… | |
… | |
164 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
340 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
165 | <dd> |
341 | <dd> |
166 | <p>This will initialise the default event loop if it hasn't been initialised |
342 | <p>This will initialise the default event loop if it hasn't been initialised |
167 | yet and return it. If the default loop could not be initialised, returns |
343 | yet and return it. If the default loop could not be initialised, returns |
168 | false. If it already was initialised it simply returns it (and ignores the |
344 | false. If it already was initialised it simply returns it (and ignores the |
169 | flags).</p> |
345 | flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p> |
170 | <p>If you don't know what event loop to use, use the one returned from this |
346 | <p>If you don't know what event loop to use, use the one returned from this |
171 | function.</p> |
347 | function.</p> |
172 | <p>The flags argument can be used to specify special behaviour or specific |
348 | <p>The flags argument can be used to specify special behaviour or specific |
173 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p> |
349 | backends to use, and is usually specified as <code>0</code> (or <code>EVFLAG_AUTO</code>).</p> |
174 | <p>It supports the following flags:</p> |
350 | <p>The following flags are supported:</p> |
175 | <p> |
351 | <p> |
176 | <dl> |
352 | <dl> |
177 | <dt><code>EVFLAG_AUTO</code></dt> |
353 | <dt><code>EVFLAG_AUTO</code></dt> |
178 | <dd> |
354 | <dd> |
179 | <p>The default flags value. Use this if you have no clue (it's the right |
355 | <p>The default flags value. Use this if you have no clue (it's the right |
… | |
… | |
186 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
362 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
187 | override the flags completely if it is found in the environment. This is |
363 | override the flags completely if it is found in the environment. This is |
188 | useful to try out specific backends to test their performance, or to work |
364 | useful to try out specific backends to test their performance, or to work |
189 | around bugs.</p> |
365 | around bugs.</p> |
190 | </dd> |
366 | </dd> |
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367 | <dt><code>EVFLAG_FORKCHECK</code></dt> |
|
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368 | <dd> |
|
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369 | <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after |
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370 | a fork, you can also make libev check for a fork in each iteration by |
|
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371 | enabling this flag.</p> |
|
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372 | <p>This works by calling <code>getpid ()</code> on every iteration of the loop, |
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373 | and thus this might slow down your event loop if you do a lot of loop |
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374 | iterations and little real work, but is usually not noticeable (on my |
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375 | Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence |
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376 | without a syscall and thus <i>very</i> fast, but my Linux system also has |
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377 | <code>pthread_atfork</code> which is even faster).</p> |
|
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378 | <p>The big advantage of this flag is that you can forget about fork (and |
|
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379 | forget about forgetting to tell libev about forking) when you use this |
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380 | flag.</p> |
|
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381 | <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code> |
|
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382 | environment variable.</p> |
|
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383 | </dd> |
191 | <dt><code>EVMETHOD_SELECT</code> (value 1, portable select backend)</dt> |
384 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
192 | <dd> |
385 | <dd> |
193 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
386 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
194 | libev tries to roll its own fd_set with no limits on the number of fds, |
387 | libev tries to roll its own fd_set with no limits on the number of fds, |
195 | but if that fails, expect a fairly low limit on the number of fds when |
388 | but if that fails, expect a fairly low limit on the number of fds when |
196 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
389 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
197 | the fastest backend for a low number of fds.</p> |
390 | the fastest backend for a low number of fds.</p> |
198 | </dd> |
391 | </dd> |
199 | <dt><code>EVMETHOD_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
392 | <dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
200 | <dd> |
393 | <dd> |
201 | <p>And this is your standard poll(2) backend. It's more complicated than |
394 | <p>And this is your standard poll(2) backend. It's more complicated than |
202 | select, but handles sparse fds better and has no artificial limit on the |
395 | select, but handles sparse fds better and has no artificial limit on the |
203 | number of fds you can use (except it will slow down considerably with a |
396 | number of fds you can use (except it will slow down considerably with a |
204 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
397 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
205 | </dd> |
398 | </dd> |
206 | <dt><code>EVMETHOD_EPOLL</code> (value 4, Linux)</dt> |
399 | <dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt> |
207 | <dd> |
400 | <dd> |
208 | <p>For few fds, this backend is a bit little slower than poll and select, |
401 | <p>For few fds, this backend is a bit little slower than poll and select, |
209 | but it scales phenomenally better. While poll and select usually scale like |
402 | but it scales phenomenally better. While poll and select usually scale like |
210 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
403 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
211 | either O(1) or O(active_fds).</p> |
404 | either O(1) or O(active_fds).</p> |
212 | <p>While stopping and starting an I/O watcher in the same iteration will |
405 | <p>While stopping and starting an I/O watcher in the same iteration will |
213 | result in some caching, there is still a syscall per such incident |
406 | result in some caching, there is still a syscall per such incident |
214 | (because the fd could point to a different file description now), so its |
407 | (because the fd could point to a different file description now), so its |
215 | best to avoid that. Also, dup()ed file descriptors might not work very |
408 | best to avoid that. Also, dup()ed file descriptors might not work very |
216 | well if you register events for both fds.</p> |
409 | well if you register events for both fds.</p> |
|
|
410 | <p>Please note that epoll sometimes generates spurious notifications, so you |
|
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411 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
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412 | (or space) is available.</p> |
217 | </dd> |
413 | </dd> |
218 | <dt><code>EVMETHOD_KQUEUE</code> (value 8, most BSD clones)</dt> |
414 | <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> |
219 | <dd> |
415 | <dd> |
220 | <p>Kqueue deserves special mention, as at the time of this writing, it |
416 | <p>Kqueue deserves special mention, as at the time of this writing, it |
221 | was broken on all BSDs except NetBSD (usually it doesn't work with |
417 | was broken on all BSDs except NetBSD (usually it doesn't work with |
222 | anything but sockets and pipes, except on Darwin, where of course its |
418 | anything but sockets and pipes, except on Darwin, where of course its |
223 | completely useless). For this reason its not being "autodetected" unless |
419 | completely useless). For this reason its not being "autodetected" |
224 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).</p> |
420 | unless you explicitly specify it explicitly in the flags (i.e. using |
|
|
421 | <code>EVBACKEND_KQUEUE</code>).</p> |
225 | <p>It scales in the same way as the epoll backend, but the interface to the |
422 | <p>It scales in the same way as the epoll backend, but the interface to the |
226 | kernel is more efficient (which says nothing about its actual speed, of |
423 | kernel is more efficient (which says nothing about its actual speed, of |
227 | course). While starting and stopping an I/O watcher does not cause an |
424 | course). While starting and stopping an I/O watcher does not cause an |
228 | extra syscall as with epoll, it still adds up to four event changes per |
425 | extra syscall as with epoll, it still adds up to four event changes per |
229 | incident, so its best to avoid that.</p> |
426 | incident, so its best to avoid that.</p> |
230 | </dd> |
427 | </dd> |
231 | <dt><code>EVMETHOD_DEVPOLL</code> (value 16, Solaris 8)</dt> |
428 | <dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt> |
232 | <dd> |
429 | <dd> |
233 | <p>This is not implemented yet (and might never be).</p> |
430 | <p>This is not implemented yet (and might never be).</p> |
234 | </dd> |
431 | </dd> |
235 | <dt><code>EVMETHOD_PORT</code> (value 32, Solaris 10)</dt> |
432 | <dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt> |
236 | <dd> |
433 | <dd> |
237 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
434 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
238 | it's really slow, but it still scales very well (O(active_fds)).</p> |
435 | it's really slow, but it still scales very well (O(active_fds)).</p> |
|
|
436 | <p>Please note that solaris ports can result in a lot of spurious |
|
|
437 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
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438 | blocking when no data (or space) is available.</p> |
239 | </dd> |
439 | </dd> |
240 | <dt><code>EVMETHOD_ALL</code></dt> |
440 | <dt><code>EVBACKEND_ALL</code></dt> |
241 | <dd> |
441 | <dd> |
242 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
442 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
243 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
443 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
244 | <code>EVMETHOD_ALL & ~EVMETHOD_KQUEUE</code>.</p> |
444 | <code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p> |
245 | </dd> |
445 | </dd> |
246 | </dl> |
446 | </dl> |
247 | </p> |
447 | </p> |
248 | <p>If one or more of these are ored into the flags value, then only these |
448 | <p>If one or more of these are ored into the flags value, then only these |
249 | backends will be tried (in the reverse order as given here). If none are |
449 | backends will be tried (in the reverse order as given here). If none are |
250 | specified, most compiled-in backend will be tried, usually in reverse |
450 | specified, most compiled-in backend will be tried, usually in reverse |
251 | order of their flag values :)</p> |
451 | order of their flag values :)</p> |
|
|
452 | <p>The most typical usage is like this:</p> |
|
|
453 | <pre> if (!ev_default_loop (0)) |
|
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454 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
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455 | |
|
|
456 | </pre> |
|
|
457 | <p>Restrict libev to the select and poll backends, and do not allow |
|
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458 | environment settings to be taken into account:</p> |
|
|
459 | <pre> ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
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460 | |
|
|
461 | </pre> |
|
|
462 | <p>Use whatever libev has to offer, but make sure that kqueue is used if |
|
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463 | available (warning, breaks stuff, best use only with your own private |
|
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464 | event loop and only if you know the OS supports your types of fds):</p> |
|
|
465 | <pre> ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
466 | |
|
|
467 | </pre> |
252 | </dd> |
468 | </dd> |
253 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
469 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
254 | <dd> |
470 | <dd> |
255 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
471 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
256 | always distinct from the default loop. Unlike the default loop, it cannot |
472 | always distinct from the default loop. Unlike the default loop, it cannot |
257 | handle signal and child watchers, and attempts to do so will be greeted by |
473 | handle signal and child watchers, and attempts to do so will be greeted by |
258 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
474 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
|
|
475 | <p>Example: Try to create a event loop that uses epoll and nothing else.</p> |
|
|
476 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
|
477 | if (!epoller) |
|
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478 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
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479 | |
|
|
480 | </pre> |
259 | </dd> |
481 | </dd> |
260 | <dt>ev_default_destroy ()</dt> |
482 | <dt>ev_default_destroy ()</dt> |
261 | <dd> |
483 | <dd> |
262 | <p>Destroys the default loop again (frees all memory and kernel state |
484 | <p>Destroys the default loop again (frees all memory and kernel state |
263 | etc.). This stops all registered event watchers (by not touching them in |
485 | etc.). None of the active event watchers will be stopped in the normal |
264 | any way whatsoever, although you cannot rely on this :).</p> |
486 | sense, so e.g. <code>ev_is_active</code> might still return true. It is your |
|
|
487 | responsibility to either stop all watchers cleanly yoursef <i>before</i> |
|
|
488 | calling this function, or cope with the fact afterwards (which is usually |
|
|
489 | the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them |
|
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490 | for example).</p> |
265 | </dd> |
491 | </dd> |
266 | <dt>ev_loop_destroy (loop)</dt> |
492 | <dt>ev_loop_destroy (loop)</dt> |
267 | <dd> |
493 | <dd> |
268 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
494 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
269 | earlier call to <code>ev_loop_new</code>.</p> |
495 | earlier call to <code>ev_loop_new</code>.</p> |
… | |
… | |
272 | <dd> |
498 | <dd> |
273 | <p>This function reinitialises the kernel state for backends that have |
499 | <p>This function reinitialises the kernel state for backends that have |
274 | one. Despite the name, you can call it anytime, but it makes most sense |
500 | one. Despite the name, you can call it anytime, but it makes most sense |
275 | after forking, in either the parent or child process (or both, but that |
501 | after forking, in either the parent or child process (or both, but that |
276 | again makes little sense).</p> |
502 | again makes little sense).</p> |
277 | <p>You <i>must</i> call this function after forking if and only if you want to |
503 | <p>You <i>must</i> call this function in the child process after forking if and |
278 | use the event library in both processes. If you just fork+exec, you don't |
504 | only if you want to use the event library in both processes. If you just |
279 | have to call it.</p> |
505 | fork+exec, you don't have to call it.</p> |
280 | <p>The function itself is quite fast and it's usually not a problem to call |
506 | <p>The function itself is quite fast and it's usually not a problem to call |
281 | it just in case after a fork. To make this easy, the function will fit in |
507 | it just in case after a fork. To make this easy, the function will fit in |
282 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
508 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
283 | <pre> pthread_atfork (0, 0, ev_default_fork); |
509 | <pre> pthread_atfork (0, 0, ev_default_fork); |
284 | |
510 | |
285 | </pre> |
511 | </pre> |
|
|
512 | <p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use |
|
|
513 | without calling this function, so if you force one of those backends you |
|
|
514 | do not need to care.</p> |
286 | </dd> |
515 | </dd> |
287 | <dt>ev_loop_fork (loop)</dt> |
516 | <dt>ev_loop_fork (loop)</dt> |
288 | <dd> |
517 | <dd> |
289 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
518 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
290 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
519 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
291 | after fork, and how you do this is entirely your own problem.</p> |
520 | after fork, and how you do this is entirely your own problem.</p> |
292 | </dd> |
521 | </dd> |
293 | <dt>unsigned int ev_method (loop)</dt> |
522 | <dt>unsigned int ev_loop_count (loop)</dt> |
|
|
523 | <dd> |
|
|
524 | <p>Returns the count of loop iterations for the loop, which is identical to |
|
|
525 | the number of times libev did poll for new events. It starts at <code>0</code> and |
|
|
526 | happily wraps around with enough iterations.</p> |
|
|
527 | <p>This value can sometimes be useful as a generation counter of sorts (it |
|
|
528 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
529 | <code>ev_prepare</code> and <code>ev_check</code> calls.</p> |
294 | <dd> |
530 | </dd> |
|
|
531 | <dt>unsigned int ev_backend (loop)</dt> |
|
|
532 | <dd> |
295 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
533 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
296 | use.</p> |
534 | use.</p> |
297 | </dd> |
535 | </dd> |
298 | <dt>ev_tstamp ev_now (loop)</dt> |
536 | <dt>ev_tstamp ev_now (loop)</dt> |
299 | <dd> |
537 | <dd> |
300 | <p>Returns the current "event loop time", which is the time the event loop |
538 | <p>Returns the current "event loop time", which is the time the event loop |
301 | got events and started processing them. This timestamp does not change |
539 | received events and started processing them. This timestamp does not |
302 | as long as callbacks are being processed, and this is also the base time |
540 | change as long as callbacks are being processed, and this is also the base |
303 | used for relative timers. You can treat it as the timestamp of the event |
541 | time used for relative timers. You can treat it as the timestamp of the |
304 | occuring (or more correctly, the mainloop finding out about it).</p> |
542 | event occuring (or more correctly, libev finding out about it).</p> |
305 | </dd> |
543 | </dd> |
306 | <dt>ev_loop (loop, int flags)</dt> |
544 | <dt>ev_loop (loop, int flags)</dt> |
307 | <dd> |
545 | <dd> |
308 | <p>Finally, this is it, the event handler. This function usually is called |
546 | <p>Finally, this is it, the event handler. This function usually is called |
309 | after you initialised all your watchers and you want to start handling |
547 | after you initialised all your watchers and you want to start handling |
310 | events.</p> |
548 | events.</p> |
311 | <p>If the flags argument is specified as 0, it will not return until either |
549 | <p>If the flags argument is specified as <code>0</code>, it will not return until |
312 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
550 | either no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
|
|
551 | <p>Please note that an explicit <code>ev_unloop</code> is usually better than |
|
|
552 | relying on all watchers to be stopped when deciding when a program has |
|
|
553 | finished (especially in interactive programs), but having a program that |
|
|
554 | automatically loops as long as it has to and no longer by virtue of |
|
|
555 | relying on its watchers stopping correctly is a thing of beauty.</p> |
313 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
556 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
314 | those events and any outstanding ones, but will not block your process in |
557 | those events and any outstanding ones, but will not block your process in |
315 | case there are no events and will return after one iteration of the loop.</p> |
558 | case there are no events and will return after one iteration of the loop.</p> |
316 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
559 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
317 | neccessary) and will handle those and any outstanding ones. It will block |
560 | neccessary) and will handle those and any outstanding ones. It will block |
318 | your process until at least one new event arrives, and will return after |
561 | your process until at least one new event arrives, and will return after |
319 | one iteration of the loop.</p> |
562 | one iteration of the loop. This is useful if you are waiting for some |
320 | <p>This flags value could be used to implement alternative looping |
563 | external event in conjunction with something not expressible using other |
321 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
564 | libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is |
322 | more generic mechanism.</p> |
565 | usually a better approach for this kind of thing.</p> |
323 | <p>Here are the gory details of what ev_loop does:</p> |
566 | <p>Here are the gory details of what <code>ev_loop</code> does:</p> |
|
|
567 | <pre> - Before the first iteration, call any pending watchers. |
324 | <pre> 1. If there are no active watchers (reference count is zero), return. |
568 | * If there are no active watchers (reference count is zero), return. |
325 | 2. Queue and immediately call all prepare watchers. |
569 | - Queue all prepare watchers and then call all outstanding watchers. |
326 | 3. If we have been forked, recreate the kernel state. |
570 | - If we have been forked, recreate the kernel state. |
327 | 4. Update the kernel state with all outstanding changes. |
571 | - Update the kernel state with all outstanding changes. |
328 | 5. Update the "event loop time". |
572 | - Update the "event loop time". |
329 | 6. Calculate for how long to block. |
573 | - Calculate for how long to block. |
330 | 7. Block the process, waiting for events. |
574 | - Block the process, waiting for any events. |
|
|
575 | - Queue all outstanding I/O (fd) events. |
331 | 8. Update the "event loop time" and do time jump handling. |
576 | - Update the "event loop time" and do time jump handling. |
332 | 9. Queue all outstanding timers. |
577 | - Queue all outstanding timers. |
333 | 10. Queue all outstanding periodics. |
578 | - Queue all outstanding periodics. |
334 | 11. If no events are pending now, queue all idle watchers. |
579 | - If no events are pending now, queue all idle watchers. |
335 | 12. Queue all check watchers. |
580 | - Queue all check watchers. |
336 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
581 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
582 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
583 | be handled here by queueing them when their watcher gets executed. |
337 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
584 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
338 | was used, return, otherwise continue with step #1. |
585 | were used, return, otherwise continue with step *. |
|
|
586 | |
|
|
587 | </pre> |
|
|
588 | <p>Example: Queue some jobs and then loop until no events are outsanding |
|
|
589 | anymore.</p> |
|
|
590 | <pre> ... queue jobs here, make sure they register event watchers as long |
|
|
591 | ... as they still have work to do (even an idle watcher will do..) |
|
|
592 | ev_loop (my_loop, 0); |
|
|
593 | ... jobs done. yeah! |
339 | |
594 | |
340 | </pre> |
595 | </pre> |
341 | </dd> |
596 | </dd> |
342 | <dt>ev_unloop (loop, how)</dt> |
597 | <dt>ev_unloop (loop, how)</dt> |
343 | <dd> |
598 | <dd> |
… | |
… | |
357 | example, libev itself uses this for its internal signal pipe: It is not |
612 | example, libev itself uses this for its internal signal pipe: It is not |
358 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
613 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
359 | no event watchers registered by it are active. It is also an excellent |
614 | no event watchers registered by it are active. It is also an excellent |
360 | way to do this for generic recurring timers or from within third-party |
615 | way to do this for generic recurring timers or from within third-party |
361 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
616 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
|
|
617 | <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code> |
|
|
618 | running when nothing else is active.</p> |
|
|
619 | <pre> struct ev_signal exitsig; |
|
|
620 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
621 | ev_signal_start (loop, &exitsig); |
|
|
622 | evf_unref (loop); |
|
|
623 | |
|
|
624 | </pre> |
|
|
625 | <p>Example: For some weird reason, unregister the above signal handler again.</p> |
|
|
626 | <pre> ev_ref (loop); |
|
|
627 | ev_signal_stop (loop, &exitsig); |
|
|
628 | |
|
|
629 | </pre> |
362 | </dd> |
630 | </dd> |
363 | </dl> |
631 | </dl> |
364 | |
632 | |
|
|
633 | |
|
|
634 | |
|
|
635 | |
|
|
636 | |
365 | </div> |
637 | </div> |
366 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
638 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1> |
367 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
639 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
368 | <p>A watcher is a structure that you create and register to record your |
640 | <p>A watcher is a structure that you create and register to record your |
369 | interest in some event. For instance, if you want to wait for STDIN to |
641 | interest in some event. For instance, if you want to wait for STDIN to |
370 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
642 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
371 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
643 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
398 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
670 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
399 | *)</code>), and you can stop watching for events at any time by calling the |
671 | *)</code>), and you can stop watching for events at any time by calling the |
400 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
672 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
401 | <p>As long as your watcher is active (has been started but not stopped) you |
673 | <p>As long as your watcher is active (has been started but not stopped) you |
402 | must not touch the values stored in it. Most specifically you must never |
674 | must not touch the values stored in it. Most specifically you must never |
403 | reinitialise it or call its set method.</p> |
675 | reinitialise it or call its <code>set</code> macro.</p> |
404 | <p>You can check whether an event is active by calling the <code>ev_is_active |
|
|
405 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
|
|
406 | callback for it has not been called yet) you can use the <code>ev_is_pending |
|
|
407 | (watcher *)</code> macro.</p> |
|
|
408 | <p>Each and every callback receives the event loop pointer as first, the |
676 | <p>Each and every callback receives the event loop pointer as first, the |
409 | registered watcher structure as second, and a bitset of received events as |
677 | registered watcher structure as second, and a bitset of received events as |
410 | third argument.</p> |
678 | third argument.</p> |
411 | <p>The received events usually include a single bit per event type received |
679 | <p>The received events usually include a single bit per event type received |
412 | (you can receive multiple events at the same time). The possible bit masks |
680 | (you can receive multiple events at the same time). The possible bit masks |
… | |
… | |
432 | </dd> |
700 | </dd> |
433 | <dt><code>EV_CHILD</code></dt> |
701 | <dt><code>EV_CHILD</code></dt> |
434 | <dd> |
702 | <dd> |
435 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
703 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
436 | </dd> |
704 | </dd> |
|
|
705 | <dt><code>EV_STAT</code></dt> |
|
|
706 | <dd> |
|
|
707 | <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p> |
|
|
708 | </dd> |
437 | <dt><code>EV_IDLE</code></dt> |
709 | <dt><code>EV_IDLE</code></dt> |
438 | <dd> |
710 | <dd> |
439 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
711 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
440 | </dd> |
712 | </dd> |
441 | <dt><code>EV_PREPARE</code></dt> |
713 | <dt><code>EV_PREPARE</code></dt> |
… | |
… | |
446 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
718 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
447 | received events. Callbacks of both watcher types can start and stop as |
719 | received events. Callbacks of both watcher types can start and stop as |
448 | many watchers as they want, and all of them will be taken into account |
720 | many watchers as they want, and all of them will be taken into account |
449 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
721 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
450 | <code>ev_loop</code> from blocking).</p> |
722 | <code>ev_loop</code> from blocking).</p> |
|
|
723 | </dd> |
|
|
724 | <dt><code>EV_EMBED</code></dt> |
|
|
725 | <dd> |
|
|
726 | <p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p> |
|
|
727 | </dd> |
|
|
728 | <dt><code>EV_FORK</code></dt> |
|
|
729 | <dd> |
|
|
730 | <p>The event loop has been resumed in the child process after fork (see |
|
|
731 | <code>ev_fork</code>).</p> |
451 | </dd> |
732 | </dd> |
452 | <dt><code>EV_ERROR</code></dt> |
733 | <dt><code>EV_ERROR</code></dt> |
453 | <dd> |
734 | <dd> |
454 | <p>An unspecified error has occured, the watcher has been stopped. This might |
735 | <p>An unspecified error has occured, the watcher has been stopped. This might |
455 | happen because the watcher could not be properly started because libev |
736 | happen because the watcher could not be properly started because libev |
… | |
… | |
463 | programs, though, so beware.</p> |
744 | programs, though, so beware.</p> |
464 | </dd> |
745 | </dd> |
465 | </dl> |
746 | </dl> |
466 | |
747 | |
467 | </div> |
748 | </div> |
|
|
749 | <h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2> |
|
|
750 | <div id="GENERIC_WATCHER_FUNCTIONS_CONTENT"> |
|
|
751 | <p>In the following description, <code>TYPE</code> stands for the watcher type, |
|
|
752 | e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> |
|
|
753 | <dl> |
|
|
754 | <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> |
|
|
755 | <dd> |
|
|
756 | <p>This macro initialises the generic portion of a watcher. The contents |
|
|
757 | of the watcher object can be arbitrary (so <code>malloc</code> will do). Only |
|
|
758 | the generic parts of the watcher are initialised, you <i>need</i> to call |
|
|
759 | the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the |
|
|
760 | type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro |
|
|
761 | which rolls both calls into one.</p> |
|
|
762 | <p>You can reinitialise a watcher at any time as long as it has been stopped |
|
|
763 | (or never started) and there are no pending events outstanding.</p> |
|
|
764 | <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
765 | int revents)</code>.</p> |
|
|
766 | </dd> |
|
|
767 | <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> |
|
|
768 | <dd> |
|
|
769 | <p>This macro initialises the type-specific parts of a watcher. You need to |
|
|
770 | call <code>ev_init</code> at least once before you call this macro, but you can |
|
|
771 | call <code>ev_TYPE_set</code> any number of times. You must not, however, call this |
|
|
772 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
773 | difference to the <code>ev_init</code> macro).</p> |
|
|
774 | <p>Although some watcher types do not have type-specific arguments |
|
|
775 | (e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p> |
|
|
776 | </dd> |
|
|
777 | <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt> |
|
|
778 | <dd> |
|
|
779 | <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro |
|
|
780 | calls into a single call. This is the most convinient method to initialise |
|
|
781 | a watcher. The same limitations apply, of course.</p> |
|
|
782 | </dd> |
|
|
783 | <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
784 | <dd> |
|
|
785 | <p>Starts (activates) the given watcher. Only active watchers will receive |
|
|
786 | events. If the watcher is already active nothing will happen.</p> |
|
|
787 | </dd> |
|
|
788 | <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
789 | <dd> |
|
|
790 | <p>Stops the given watcher again (if active) and clears the pending |
|
|
791 | status. It is possible that stopped watchers are pending (for example, |
|
|
792 | non-repeating timers are being stopped when they become pending), but |
|
|
793 | <code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If |
|
|
794 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
795 | good idea to always call its <code>ev_TYPE_stop</code> function.</p> |
|
|
796 | </dd> |
|
|
797 | <dt>bool ev_is_active (ev_TYPE *watcher)</dt> |
|
|
798 | <dd> |
|
|
799 | <p>Returns a true value iff the watcher is active (i.e. it has been started |
|
|
800 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
801 | it.</p> |
|
|
802 | </dd> |
|
|
803 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
|
|
804 | <dd> |
|
|
805 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
806 | events but its callback has not yet been invoked). As long as a watcher |
|
|
807 | is pending (but not active) you must not call an init function on it (but |
|
|
808 | <code>ev_TYPE_set</code> is safe), you must not change its priority, and you must |
|
|
809 | make sure the watcher is available to libev (e.g. you cannot <code>free ()</code> |
|
|
810 | it).</p> |
|
|
811 | </dd> |
|
|
812 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
|
|
813 | <dd> |
|
|
814 | <p>Returns the callback currently set on the watcher.</p> |
|
|
815 | </dd> |
|
|
816 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
|
|
817 | <dd> |
|
|
818 | <p>Change the callback. You can change the callback at virtually any time |
|
|
819 | (modulo threads).</p> |
|
|
820 | </dd> |
|
|
821 | <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt> |
|
|
822 | <dt>int ev_priority (ev_TYPE *watcher)</dt> |
|
|
823 | <dd> |
|
|
824 | <p>Set and query the priority of the watcher. The priority is a small |
|
|
825 | integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code> |
|
|
826 | (default: <code>-2</code>). Pending watchers with higher priority will be invoked |
|
|
827 | before watchers with lower priority, but priority will not keep watchers |
|
|
828 | from being executed (except for <code>ev_idle</code> watchers).</p> |
|
|
829 | <p>This means that priorities are <i>only</i> used for ordering callback |
|
|
830 | invocation after new events have been received. This is useful, for |
|
|
831 | example, to reduce latency after idling, or more often, to bind two |
|
|
832 | watchers on the same event and make sure one is called first.</p> |
|
|
833 | <p>If you need to suppress invocation when higher priority events are pending |
|
|
834 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
|
|
835 | <p>You <i>must not</i> change the priority of a watcher as long as it is active or |
|
|
836 | pending.</p> |
|
|
837 | <p>The default priority used by watchers when no priority has been set is |
|
|
838 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
|
|
839 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
|
|
840 | fine, as long as you do not mind that the priority value you query might |
|
|
841 | or might not have been adjusted to be within valid range.</p> |
|
|
842 | </dd> |
|
|
843 | <dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt> |
|
|
844 | <dd> |
|
|
845 | <p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither |
|
|
846 | <code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback |
|
|
847 | can deal with that fact.</p> |
|
|
848 | </dd> |
|
|
849 | <dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt> |
|
|
850 | <dd> |
|
|
851 | <p>If the watcher is pending, this function returns clears its pending status |
|
|
852 | and returns its <code>revents</code> bitset (as if its callback was invoked). If the |
|
|
853 | watcher isn't pending it does nothing and returns <code>0</code>.</p> |
|
|
854 | </dd> |
|
|
855 | </dl> |
|
|
856 | |
|
|
857 | |
|
|
858 | |
|
|
859 | |
|
|
860 | |
|
|
861 | </div> |
468 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
862 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
469 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
863 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
470 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
864 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
471 | and read at any time, libev will completely ignore it. This can be used |
865 | and read at any time, libev will completely ignore it. This can be used |
472 | to associate arbitrary data with your watcher. If you need more data and |
866 | to associate arbitrary data with your watcher. If you need more data and |
… | |
… | |
489 | struct my_io *w = (struct my_io *)w_; |
883 | struct my_io *w = (struct my_io *)w_; |
490 | ... |
884 | ... |
491 | } |
885 | } |
492 | |
886 | |
493 | </pre> |
887 | </pre> |
494 | <p>More interesting and less C-conformant ways of catsing your callback type |
888 | <p>More interesting and less C-conformant ways of casting your callback type |
495 | have been omitted....</p> |
889 | instead have been omitted.</p> |
|
|
890 | <p>Another common scenario is having some data structure with multiple |
|
|
891 | watchers:</p> |
|
|
892 | <pre> struct my_biggy |
|
|
893 | { |
|
|
894 | int some_data; |
|
|
895 | ev_timer t1; |
|
|
896 | ev_timer t2; |
|
|
897 | } |
496 | |
898 | |
|
|
899 | </pre> |
|
|
900 | <p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated, |
|
|
901 | you need to use <code>offsetof</code>:</p> |
|
|
902 | <pre> #include <stddef.h> |
497 | |
903 | |
|
|
904 | static void |
|
|
905 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
906 | { |
|
|
907 | struct my_biggy big = (struct my_biggy * |
|
|
908 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
909 | } |
498 | |
910 | |
|
|
911 | static void |
|
|
912 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
913 | { |
|
|
914 | struct my_biggy big = (struct my_biggy * |
|
|
915 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
916 | } |
499 | |
917 | |
500 | |
918 | |
|
|
919 | |
|
|
920 | |
|
|
921 | </pre> |
|
|
922 | |
501 | </div> |
923 | </div> |
502 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
924 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
503 | <div id="WATCHER_TYPES_CONTENT"> |
925 | <div id="WATCHER_TYPES_CONTENT"> |
504 | <p>This section describes each watcher in detail, but will not repeat |
926 | <p>This section describes each watcher in detail, but will not repeat |
505 | information given in the last section.</p> |
927 | information given in the last section. Any initialisation/set macros, |
|
|
928 | functions and members specific to the watcher type are explained.</p> |
|
|
929 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
|
|
930 | while the watcher is active, you can look at the member and expect some |
|
|
931 | sensible content, but you must not modify it (you can modify it while the |
|
|
932 | watcher is stopped to your hearts content), or <i>[read-write]</i>, which |
|
|
933 | means you can expect it to have some sensible content while the watcher |
|
|
934 | is active, but you can also modify it. Modifying it may not do something |
|
|
935 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
936 | not crash or malfunction in any way.</p> |
506 | |
937 | |
|
|
938 | |
|
|
939 | |
|
|
940 | |
|
|
941 | |
507 | </div> |
942 | </div> |
508 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
943 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2> |
509 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
944 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
510 | <p>I/O watchers check whether a file descriptor is readable or writable |
945 | <p>I/O watchers check whether a file descriptor is readable or writable |
511 | in each iteration of the event loop (This behaviour is called |
946 | in each iteration of the event loop, or, more precisely, when reading |
512 | level-triggering because you keep receiving events as long as the |
947 | would not block the process and writing would at least be able to write |
513 | condition persists. Remember you can stop the watcher if you don't want to |
948 | some data. This behaviour is called level-triggering because you keep |
514 | act on the event and neither want to receive future events).</p> |
949 | receiving events as long as the condition persists. Remember you can stop |
|
|
950 | the watcher if you don't want to act on the event and neither want to |
|
|
951 | receive future events.</p> |
515 | <p>In general you can register as many read and/or write event watchers per |
952 | <p>In general you can register as many read and/or write event watchers per |
516 | fd as you want (as long as you don't confuse yourself). Setting all file |
953 | fd as you want (as long as you don't confuse yourself). Setting all file |
517 | descriptors to non-blocking mode is also usually a good idea (but not |
954 | descriptors to non-blocking mode is also usually a good idea (but not |
518 | required if you know what you are doing).</p> |
955 | required if you know what you are doing).</p> |
519 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
956 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
520 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
957 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
521 | descriptors correctly if you register interest in two or more fds pointing |
958 | descriptors correctly if you register interest in two or more fds pointing |
522 | to the same underlying file/socket etc. description (that is, they share |
959 | to the same underlying file/socket/etc. description (that is, they share |
523 | the same underlying "file open").</p> |
960 | the same underlying "file open").</p> |
524 | <p>If you must do this, then force the use of a known-to-be-good backend |
961 | <p>If you must do this, then force the use of a known-to-be-good backend |
525 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
962 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
526 | EVMETHOD_POLL).</p> |
963 | <code>EVBACKEND_POLL</code>).</p> |
|
|
964 | <p>Another thing you have to watch out for is that it is quite easy to |
|
|
965 | receive "spurious" readyness notifications, that is your callback might |
|
|
966 | be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block |
|
|
967 | because there is no data. Not only are some backends known to create a |
|
|
968 | lot of those (for example solaris ports), it is very easy to get into |
|
|
969 | this situation even with a relatively standard program structure. Thus |
|
|
970 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
|
|
971 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
|
|
972 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
|
|
973 | play around with an Xlib connection), then you have to seperately re-test |
|
|
974 | whether a file descriptor is really ready with a known-to-be good interface |
|
|
975 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
976 | its own, so its quite safe to use).</p> |
|
|
977 | |
|
|
978 | </div> |
|
|
979 | <h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3> |
|
|
980 | <div id="The_special_problem_of_disappearing_-2"> |
|
|
981 | <p>Some backends (e.g kqueue, epoll) need to be told about closing a file |
|
|
982 | descriptor (either by calling <code>close</code> explicitly or by any other means, |
|
|
983 | such as <code>dup</code>). The reason is that you register interest in some file |
|
|
984 | descriptor, but when it goes away, the operating system will silently drop |
|
|
985 | this interest. If another file descriptor with the same number then is |
|
|
986 | registered with libev, there is no efficient way to see that this is, in |
|
|
987 | fact, a different file descriptor.</p> |
|
|
988 | <p>To avoid having to explicitly tell libev about such cases, libev follows |
|
|
989 | the following policy: Each time <code>ev_io_set</code> is being called, libev |
|
|
990 | will assume that this is potentially a new file descriptor, otherwise |
|
|
991 | it is assumed that the file descriptor stays the same. That means that |
|
|
992 | you <i>have</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the |
|
|
993 | descriptor even if the file descriptor number itself did not change.</p> |
|
|
994 | <p>This is how one would do it normally anyway, the important point is that |
|
|
995 | the libev application should not optimise around libev but should leave |
|
|
996 | optimisations to libev.</p> |
|
|
997 | |
|
|
998 | |
|
|
999 | |
|
|
1000 | |
|
|
1001 | |
|
|
1002 | </div> |
|
|
1003 | <h3 id="Watcher_Specific_Functions">Watcher-Specific Functions</h3> |
|
|
1004 | <div id="Watcher_Specific_Functions_CONTENT"> |
527 | <dl> |
1005 | <dl> |
528 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
1006 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
529 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
1007 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
530 | <dd> |
1008 | <dd> |
531 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
1009 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
532 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
1010 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
533 | EV_WRITE</code> to receive the given events.</p> |
1011 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
|
|
1012 | </dd> |
|
|
1013 | <dt>int fd [read-only]</dt> |
|
|
1014 | <dd> |
|
|
1015 | <p>The file descriptor being watched.</p> |
|
|
1016 | </dd> |
|
|
1017 | <dt>int events [read-only]</dt> |
|
|
1018 | <dd> |
|
|
1019 | <p>The events being watched.</p> |
534 | </dd> |
1020 | </dd> |
535 | </dl> |
1021 | </dl> |
|
|
1022 | <p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
|
|
1023 | readable, but only once. Since it is likely line-buffered, you could |
|
|
1024 | attempt to read a whole line in the callback.</p> |
|
|
1025 | <pre> static void |
|
|
1026 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1027 | { |
|
|
1028 | ev_io_stop (loop, w); |
|
|
1029 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
1030 | } |
536 | |
1031 | |
|
|
1032 | ... |
|
|
1033 | struct ev_loop *loop = ev_default_init (0); |
|
|
1034 | struct ev_io stdin_readable; |
|
|
1035 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
1036 | ev_io_start (loop, &stdin_readable); |
|
|
1037 | ev_loop (loop, 0); |
|
|
1038 | |
|
|
1039 | |
|
|
1040 | |
|
|
1041 | |
|
|
1042 | </pre> |
|
|
1043 | |
537 | </div> |
1044 | </div> |
538 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
1045 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2> |
539 | <div id="code_ev_timer_code_relative_and_opti-2"> |
1046 | <div id="code_ev_timer_code_relative_and_opti-2"> |
540 | <p>Timer watchers are simple relative timers that generate an event after a |
1047 | <p>Timer watchers are simple relative timers that generate an event after a |
541 | given time, and optionally repeating in regular intervals after that.</p> |
1048 | given time, and optionally repeating in regular intervals after that.</p> |
542 | <p>The timers are based on real time, that is, if you register an event that |
1049 | <p>The timers are based on real time, that is, if you register an event that |
543 | times out after an hour and you reset your system clock to last years |
1050 | times out after an hour and you reset your system clock to last years |
… | |
… | |
553 | |
1060 | |
554 | </pre> |
1061 | </pre> |
555 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
1062 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
556 | but if multiple timers become ready during the same loop iteration then |
1063 | but if multiple timers become ready during the same loop iteration then |
557 | order of execution is undefined.</p> |
1064 | order of execution is undefined.</p> |
|
|
1065 | |
|
|
1066 | </div> |
|
|
1067 | <h3 id="Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</h3> |
|
|
1068 | <div id="Watcher_Specific_Functions_and_Data_-2"> |
558 | <dl> |
1069 | <dl> |
559 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
1070 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
560 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
1071 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
561 | <dd> |
1072 | <dd> |
562 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
1073 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
571 | </dd> |
1082 | </dd> |
572 | <dt>ev_timer_again (loop)</dt> |
1083 | <dt>ev_timer_again (loop)</dt> |
573 | <dd> |
1084 | <dd> |
574 | <p>This will act as if the timer timed out and restart it again if it is |
1085 | <p>This will act as if the timer timed out and restart it again if it is |
575 | repeating. The exact semantics are:</p> |
1086 | repeating. The exact semantics are:</p> |
|
|
1087 | <p>If the timer is pending, its pending status is cleared.</p> |
576 | <p>If the timer is started but nonrepeating, stop it.</p> |
1088 | <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p> |
577 | <p>If the timer is repeating, either start it if necessary (with the repeat |
1089 | <p>If the timer is repeating, either start it if necessary (with the |
578 | value), or reset the running timer to the repeat value.</p> |
1090 | <code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p> |
579 | <p>This sounds a bit complicated, but here is a useful and typical |
1091 | <p>This sounds a bit complicated, but here is a useful and typical |
580 | example: Imagine you have a tcp connection and you want a so-called idle |
1092 | example: Imagine you have a tcp connection and you want a so-called idle |
581 | timeout, that is, you want to be called when there have been, say, 60 |
1093 | timeout, that is, you want to be called when there have been, say, 60 |
582 | seconds of inactivity on the socket. The easiest way to do this is to |
1094 | seconds of inactivity on the socket. The easiest way to do this is to |
583 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
1095 | configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call |
584 | time you successfully read or write some data. If you go into an idle |
1096 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
585 | state where you do not expect data to travel on the socket, you can stop |
1097 | you go into an idle state where you do not expect data to travel on the |
|
|
1098 | socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will |
586 | the timer, and again will automatically restart it if need be.</p> |
1099 | automatically restart it if need be.</p> |
|
|
1100 | <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code> |
|
|
1101 | altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p> |
|
|
1102 | <pre> ev_timer_init (timer, callback, 0., 5.); |
|
|
1103 | ev_timer_again (loop, timer); |
|
|
1104 | ... |
|
|
1105 | timer->again = 17.; |
|
|
1106 | ev_timer_again (loop, timer); |
|
|
1107 | ... |
|
|
1108 | timer->again = 10.; |
|
|
1109 | ev_timer_again (loop, timer); |
|
|
1110 | |
|
|
1111 | </pre> |
|
|
1112 | <p>This is more slightly efficient then stopping/starting the timer each time |
|
|
1113 | you want to modify its timeout value.</p> |
|
|
1114 | </dd> |
|
|
1115 | <dt>ev_tstamp repeat [read-write]</dt> |
|
|
1116 | <dd> |
|
|
1117 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
|
|
1118 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
|
|
1119 | which is also when any modifications are taken into account.</p> |
587 | </dd> |
1120 | </dd> |
588 | </dl> |
1121 | </dl> |
|
|
1122 | <p>Example: Create a timer that fires after 60 seconds.</p> |
|
|
1123 | <pre> static void |
|
|
1124 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1125 | { |
|
|
1126 | .. one minute over, w is actually stopped right here |
|
|
1127 | } |
589 | |
1128 | |
|
|
1129 | struct ev_timer mytimer; |
|
|
1130 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
1131 | ev_timer_start (loop, &mytimer); |
|
|
1132 | |
|
|
1133 | </pre> |
|
|
1134 | <p>Example: Create a timeout timer that times out after 10 seconds of |
|
|
1135 | inactivity.</p> |
|
|
1136 | <pre> static void |
|
|
1137 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1138 | { |
|
|
1139 | .. ten seconds without any activity |
|
|
1140 | } |
|
|
1141 | |
|
|
1142 | struct ev_timer mytimer; |
|
|
1143 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
1144 | ev_timer_again (&mytimer); /* start timer */ |
|
|
1145 | ev_loop (loop, 0); |
|
|
1146 | |
|
|
1147 | // and in some piece of code that gets executed on any "activity": |
|
|
1148 | // reset the timeout to start ticking again at 10 seconds |
|
|
1149 | ev_timer_again (&mytimer); |
|
|
1150 | |
|
|
1151 | |
|
|
1152 | |
|
|
1153 | |
|
|
1154 | </pre> |
|
|
1155 | |
590 | </div> |
1156 | </div> |
591 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
1157 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2> |
592 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
1158 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
593 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
1159 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
594 | (and unfortunately a bit complex).</p> |
1160 | (and unfortunately a bit complex).</p> |
595 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
1161 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
596 | but on wallclock time (absolute time). You can tell a periodic watcher |
1162 | but on wallclock time (absolute time). You can tell a periodic watcher |
597 | to trigger "at" some specific point in time. For example, if you tell a |
1163 | to trigger "at" some specific point in time. For example, if you tell a |
598 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
1164 | periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () |
599 | + 10.>) and then reset your system clock to the last year, then it will |
1165 | + 10.</code>) and then reset your system clock to the last year, then it will |
600 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
1166 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
601 | roughly 10 seconds later and of course not if you reset your system time |
1167 | roughly 10 seconds later).</p> |
602 | again).</p> |
|
|
603 | <p>They can also be used to implement vastly more complex timers, such as |
1168 | <p>They can also be used to implement vastly more complex timers, such as |
604 | triggering an event on eahc midnight, local time.</p> |
1169 | triggering an event on each midnight, local time or other, complicated, |
|
|
1170 | rules.</p> |
605 | <p>As with timers, the callback is guarenteed to be invoked only when the |
1171 | <p>As with timers, the callback is guarenteed to be invoked only when the |
606 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
1172 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
607 | during the same loop iteration then order of execution is undefined.</p> |
1173 | during the same loop iteration then order of execution is undefined.</p> |
|
|
1174 | |
|
|
1175 | </div> |
|
|
1176 | <h3 id="Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</h3> |
|
|
1177 | <div id="Watcher_Specific_Functions_and_Data_-2"> |
608 | <dl> |
1178 | <dl> |
609 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
1179 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
610 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
1180 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
611 | <dd> |
1181 | <dd> |
612 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
1182 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
613 | operation, and we will explain them from simplest to complex:</p> |
1183 | operation, and we will explain them from simplest to complex:</p> |
614 | <p> |
1184 | <p> |
615 | <dl> |
1185 | <dl> |
616 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
1186 | <dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt> |
617 | <dd> |
1187 | <dd> |
618 | <p>In this configuration the watcher triggers an event at the wallclock time |
1188 | <p>In this configuration the watcher triggers an event at the wallclock time |
619 | <code>at</code> and doesn't repeat. It will not adjust when a time jump occurs, |
1189 | <code>at</code> and doesn't repeat. It will not adjust when a time jump occurs, |
620 | that is, if it is to be run at January 1st 2011 then it will run when the |
1190 | that is, if it is to be run at January 1st 2011 then it will run when the |
621 | system time reaches or surpasses this time.</p> |
1191 | system time reaches or surpasses this time.</p> |
622 | </dd> |
1192 | </dd> |
623 | <dt>* non-repeating interval timer (interval > 0, reschedule_cb = 0)</dt> |
1193 | <dt>* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)</dt> |
624 | <dd> |
1194 | <dd> |
625 | <p>In this mode the watcher will always be scheduled to time out at the next |
1195 | <p>In this mode the watcher will always be scheduled to time out at the next |
626 | <code>at + N * interval</code> time (for some integer N) and then repeat, regardless |
1196 | <code>at + N * interval</code> time (for some integer N, which can also be negative) |
627 | of any time jumps.</p> |
1197 | and then repeat, regardless of any time jumps.</p> |
628 | <p>This can be used to create timers that do not drift with respect to system |
1198 | <p>This can be used to create timers that do not drift with respect to system |
629 | time:</p> |
1199 | time:</p> |
630 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
1200 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
631 | |
1201 | |
632 | </pre> |
1202 | </pre> |
… | |
… | |
635 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1205 | full hour (UTC), or more correctly, when the system time is evenly divisible |
636 | by 3600.</p> |
1206 | by 3600.</p> |
637 | <p>Another way to think about it (for the mathematically inclined) is that |
1207 | <p>Another way to think about it (for the mathematically inclined) is that |
638 | <code>ev_periodic</code> will try to run the callback in this mode at the next possible |
1208 | <code>ev_periodic</code> will try to run the callback in this mode at the next possible |
639 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
1209 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
|
|
1210 | <p>For numerical stability it is preferable that the <code>at</code> value is near |
|
|
1211 | <code>ev_now ()</code> (the current time), but there is no range requirement for |
|
|
1212 | this value.</p> |
640 | </dd> |
1213 | </dd> |
641 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
1214 | <dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt> |
642 | <dd> |
1215 | <dd> |
643 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
1216 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
644 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1217 | ignored. Instead, each time the periodic watcher gets scheduled, the |
645 | reschedule callback will be called with the watcher as first, and the |
1218 | reschedule callback will be called with the watcher as first, and the |
646 | current time as second argument.</p> |
1219 | current time as second argument.</p> |
647 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
1220 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
648 | ever, or make any event loop modifications</i>. If you need to stop it, |
1221 | ever, or make any event loop modifications</i>. If you need to stop it, |
649 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
1222 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
650 | starting a prepare watcher).</p> |
1223 | starting an <code>ev_prepare</code> watcher, which is legal).</p> |
651 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1224 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
652 | ev_tstamp now)</code>, e.g.:</p> |
1225 | ev_tstamp now)</code>, e.g.:</p> |
653 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1226 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
654 | { |
1227 | { |
655 | return now + 60.; |
1228 | return now + 60.; |
… | |
… | |
676 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1249 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
677 | when you changed some parameters or the reschedule callback would return |
1250 | when you changed some parameters or the reschedule callback would return |
678 | a different time than the last time it was called (e.g. in a crond like |
1251 | a different time than the last time it was called (e.g. in a crond like |
679 | program when the crontabs have changed).</p> |
1252 | program when the crontabs have changed).</p> |
680 | </dd> |
1253 | </dd> |
|
|
1254 | <dt>ev_tstamp offset [read-write]</dt> |
|
|
1255 | <dd> |
|
|
1256 | <p>When repeating, this contains the offset value, otherwise this is the |
|
|
1257 | absolute point in time (the <code>at</code> value passed to <code>ev_periodic_set</code>).</p> |
|
|
1258 | <p>Can be modified any time, but changes only take effect when the periodic |
|
|
1259 | timer fires or <code>ev_periodic_again</code> is being called.</p> |
|
|
1260 | </dd> |
|
|
1261 | <dt>ev_tstamp interval [read-write]</dt> |
|
|
1262 | <dd> |
|
|
1263 | <p>The current interval value. Can be modified any time, but changes only |
|
|
1264 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
|
|
1265 | called.</p> |
|
|
1266 | </dd> |
|
|
1267 | <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt> |
|
|
1268 | <dd> |
|
|
1269 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
|
|
1270 | switched off. Can be changed any time, but changes only take effect when |
|
|
1271 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
|
|
1272 | </dd> |
681 | </dl> |
1273 | </dl> |
|
|
1274 | <p>Example: Call a callback every hour, or, more precisely, whenever the |
|
|
1275 | system clock is divisible by 3600. The callback invocation times have |
|
|
1276 | potentially a lot of jittering, but good long-term stability.</p> |
|
|
1277 | <pre> static void |
|
|
1278 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1279 | { |
|
|
1280 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
1281 | } |
682 | |
1282 | |
|
|
1283 | struct ev_periodic hourly_tick; |
|
|
1284 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
1285 | ev_periodic_start (loop, &hourly_tick); |
|
|
1286 | |
|
|
1287 | </pre> |
|
|
1288 | <p>Example: The same as above, but use a reschedule callback to do it:</p> |
|
|
1289 | <pre> #include <math.h> |
|
|
1290 | |
|
|
1291 | static ev_tstamp |
|
|
1292 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1293 | { |
|
|
1294 | return fmod (now, 3600.) + 3600.; |
|
|
1295 | } |
|
|
1296 | |
|
|
1297 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1298 | |
|
|
1299 | </pre> |
|
|
1300 | <p>Example: Call a callback every hour, starting now:</p> |
|
|
1301 | <pre> struct ev_periodic hourly_tick; |
|
|
1302 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1303 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1304 | ev_periodic_start (loop, &hourly_tick); |
|
|
1305 | |
|
|
1306 | |
|
|
1307 | |
|
|
1308 | |
|
|
1309 | </pre> |
|
|
1310 | |
683 | </div> |
1311 | </div> |
684 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
1312 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2> |
685 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
1313 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
686 | <p>Signal watchers will trigger an event when the process receives a specific |
1314 | <p>Signal watchers will trigger an event when the process receives a specific |
687 | signal one or more times. Even though signals are very asynchronous, libev |
1315 | signal one or more times. Even though signals are very asynchronous, libev |
688 | will try it's best to deliver signals synchronously, i.e. as part of the |
1316 | will try it's best to deliver signals synchronously, i.e. as part of the |
689 | normal event processing, like any other event.</p> |
1317 | normal event processing, like any other event.</p> |
… | |
… | |
691 | first watcher gets started will libev actually register a signal watcher |
1319 | first watcher gets started will libev actually register a signal watcher |
692 | with the kernel (thus it coexists with your own signal handlers as long |
1320 | with the kernel (thus it coexists with your own signal handlers as long |
693 | as you don't register any with libev). Similarly, when the last signal |
1321 | as you don't register any with libev). Similarly, when the last signal |
694 | watcher for a signal is stopped libev will reset the signal handler to |
1322 | watcher for a signal is stopped libev will reset the signal handler to |
695 | SIG_DFL (regardless of what it was set to before).</p> |
1323 | SIG_DFL (regardless of what it was set to before).</p> |
|
|
1324 | |
|
|
1325 | </div> |
|
|
1326 | <h3 id="Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</h3> |
|
|
1327 | <div id="Watcher_Specific_Functions_and_Data_-2-2"> |
696 | <dl> |
1328 | <dl> |
697 | <dt>ev_signal_init (ev_signal *, callback, int signum)</dt> |
1329 | <dt>ev_signal_init (ev_signal *, callback, int signum)</dt> |
698 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1330 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
699 | <dd> |
1331 | <dd> |
700 | <p>Configures the watcher to trigger on the given signal number (usually one |
1332 | <p>Configures the watcher to trigger on the given signal number (usually one |
701 | of the <code>SIGxxx</code> constants).</p> |
1333 | of the <code>SIGxxx</code> constants).</p> |
702 | </dd> |
1334 | </dd> |
|
|
1335 | <dt>int signum [read-only]</dt> |
|
|
1336 | <dd> |
|
|
1337 | <p>The signal the watcher watches out for.</p> |
|
|
1338 | </dd> |
703 | </dl> |
1339 | </dl> |
704 | |
1340 | |
|
|
1341 | |
|
|
1342 | |
|
|
1343 | |
|
|
1344 | |
705 | </div> |
1345 | </div> |
706 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
1346 | <h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> |
707 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
1347 | <div id="code_ev_child_code_watch_out_for_pro-2"> |
708 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1348 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
709 | some child status changes (most typically when a child of yours dies).</p> |
1349 | some child status changes (most typically when a child of yours dies).</p> |
|
|
1350 | |
|
|
1351 | </div> |
|
|
1352 | <h3 id="Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</h3> |
|
|
1353 | <div id="Watcher_Specific_Functions_and_Data_-2-3"> |
710 | <dl> |
1354 | <dl> |
711 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1355 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
712 | <dt>ev_child_set (ev_child *, int pid)</dt> |
1356 | <dt>ev_child_set (ev_child *, int pid)</dt> |
713 | <dd> |
1357 | <dd> |
714 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
1358 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
… | |
… | |
716 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1360 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
717 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1361 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
718 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1362 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
719 | process causing the status change.</p> |
1363 | process causing the status change.</p> |
720 | </dd> |
1364 | </dd> |
|
|
1365 | <dt>int pid [read-only]</dt> |
|
|
1366 | <dd> |
|
|
1367 | <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p> |
|
|
1368 | </dd> |
|
|
1369 | <dt>int rpid [read-write]</dt> |
|
|
1370 | <dd> |
|
|
1371 | <p>The process id that detected a status change.</p> |
|
|
1372 | </dd> |
|
|
1373 | <dt>int rstatus [read-write]</dt> |
|
|
1374 | <dd> |
|
|
1375 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
|
|
1376 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
|
|
1377 | </dd> |
721 | </dl> |
1378 | </dl> |
|
|
1379 | <p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p> |
|
|
1380 | <pre> static void |
|
|
1381 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1382 | { |
|
|
1383 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1384 | } |
722 | |
1385 | |
|
|
1386 | struct ev_signal signal_watcher; |
|
|
1387 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1388 | ev_signal_start (loop, &sigint_cb); |
|
|
1389 | |
|
|
1390 | |
|
|
1391 | |
|
|
1392 | |
|
|
1393 | </pre> |
|
|
1394 | |
723 | </div> |
1395 | </div> |
|
|
1396 | <h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2> |
|
|
1397 | <div id="code_ev_stat_code_did_the_file_attri-2"> |
|
|
1398 | <p>This watches a filesystem path for attribute changes. That is, it calls |
|
|
1399 | <code>stat</code> regularly (or when the OS says it changed) and sees if it changed |
|
|
1400 | compared to the last time, invoking the callback if it did.</p> |
|
|
1401 | <p>The path does not need to exist: changing from "path exists" to "path does |
|
|
1402 | not exist" is a status change like any other. The condition "path does |
|
|
1403 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
|
|
1404 | otherwise always forced to be at least one) and all the other fields of |
|
|
1405 | the stat buffer having unspecified contents.</p> |
|
|
1406 | <p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is |
|
|
1407 | relative and your working directory changes, the behaviour is undefined.</p> |
|
|
1408 | <p>Since there is no standard to do this, the portable implementation simply |
|
|
1409 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
|
|
1410 | can specify a recommended polling interval for this case. If you specify |
|
|
1411 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
|
|
1412 | unspecified default</i> value will be used (which you can expect to be around |
|
|
1413 | five seconds, although this might change dynamically). Libev will also |
|
|
1414 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
|
|
1415 | usually overkill.</p> |
|
|
1416 | <p>This watcher type is not meant for massive numbers of stat watchers, |
|
|
1417 | as even with OS-supported change notifications, this can be |
|
|
1418 | resource-intensive.</p> |
|
|
1419 | <p>At the time of this writing, only the Linux inotify interface is |
|
|
1420 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1421 | reader). Inotify will be used to give hints only and should not change the |
|
|
1422 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
|
|
1423 | to fall back to regular polling again even with inotify, but changes are |
|
|
1424 | usually detected immediately, and if the file exists there will be no |
|
|
1425 | polling.</p> |
|
|
1426 | |
|
|
1427 | </div> |
|
|
1428 | <h3 id="Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</h3> |
|
|
1429 | <div id="Watcher_Specific_Functions_and_Data_-2-4"> |
|
|
1430 | <dl> |
|
|
1431 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
|
|
1432 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
|
|
1433 | <dd> |
|
|
1434 | <p>Configures the watcher to wait for status changes of the given |
|
|
1435 | <code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to |
|
|
1436 | be detected and should normally be specified as <code>0</code> to let libev choose |
|
|
1437 | a suitable value. The memory pointed to by <code>path</code> must point to the same |
|
|
1438 | path for as long as the watcher is active.</p> |
|
|
1439 | <p>The callback will be receive <code>EV_STAT</code> when a change was detected, |
|
|
1440 | relative to the attributes at the time the watcher was started (or the |
|
|
1441 | last change was detected).</p> |
|
|
1442 | </dd> |
|
|
1443 | <dt>ev_stat_stat (ev_stat *)</dt> |
|
|
1444 | <dd> |
|
|
1445 | <p>Updates the stat buffer immediately with new values. If you change the |
|
|
1446 | watched path in your callback, you could call this fucntion to avoid |
|
|
1447 | detecting this change (while introducing a race condition). Can also be |
|
|
1448 | useful simply to find out the new values.</p> |
|
|
1449 | </dd> |
|
|
1450 | <dt>ev_statdata attr [read-only]</dt> |
|
|
1451 | <dd> |
|
|
1452 | <p>The most-recently detected attributes of the file. Although the type is of |
|
|
1453 | <code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types |
|
|
1454 | suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there |
|
|
1455 | was some error while <code>stat</code>ing the file.</p> |
|
|
1456 | </dd> |
|
|
1457 | <dt>ev_statdata prev [read-only]</dt> |
|
|
1458 | <dd> |
|
|
1459 | <p>The previous attributes of the file. The callback gets invoked whenever |
|
|
1460 | <code>prev</code> != <code>attr</code>.</p> |
|
|
1461 | </dd> |
|
|
1462 | <dt>ev_tstamp interval [read-only]</dt> |
|
|
1463 | <dd> |
|
|
1464 | <p>The specified interval.</p> |
|
|
1465 | </dd> |
|
|
1466 | <dt>const char *path [read-only]</dt> |
|
|
1467 | <dd> |
|
|
1468 | <p>The filesystem path that is being watched.</p> |
|
|
1469 | </dd> |
|
|
1470 | </dl> |
|
|
1471 | <p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p> |
|
|
1472 | <pre> static void |
|
|
1473 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1474 | { |
|
|
1475 | /* /etc/passwd changed in some way */ |
|
|
1476 | if (w->attr.st_nlink) |
|
|
1477 | { |
|
|
1478 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1479 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1480 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1481 | } |
|
|
1482 | else |
|
|
1483 | /* you shalt not abuse printf for puts */ |
|
|
1484 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1485 | "if this is windows, they already arrived\n"); |
|
|
1486 | } |
|
|
1487 | |
|
|
1488 | ... |
|
|
1489 | ev_stat passwd; |
|
|
1490 | |
|
|
1491 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1492 | ev_stat_start (loop, &passwd); |
|
|
1493 | |
|
|
1494 | |
|
|
1495 | |
|
|
1496 | |
|
|
1497 | </pre> |
|
|
1498 | |
|
|
1499 | </div> |
724 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
1500 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
725 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1501 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
726 | <p>Idle watchers trigger events when there are no other events are pending |
1502 | <p>Idle watchers trigger events when no other events of the same or higher |
727 | (prepare, check and other idle watchers do not count). That is, as long |
1503 | priority are pending (prepare, check and other idle watchers do not |
728 | as your process is busy handling sockets or timeouts (or even signals, |
1504 | count).</p> |
729 | imagine) it will not be triggered. But when your process is idle all idle |
1505 | <p>That is, as long as your process is busy handling sockets or timeouts |
730 | watchers are being called again and again, once per event loop iteration - |
1506 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1507 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1508 | are pending), the idle watchers are being called once per event loop |
731 | until stopped, that is, or your process receives more events and becomes |
1509 | iteration - until stopped, that is, or your process receives more events |
732 | busy.</p> |
1510 | and becomes busy again with higher priority stuff.</p> |
733 | <p>The most noteworthy effect is that as long as any idle watchers are |
1511 | <p>The most noteworthy effect is that as long as any idle watchers are |
734 | active, the process will not block when waiting for new events.</p> |
1512 | active, the process will not block when waiting for new events.</p> |
735 | <p>Apart from keeping your process non-blocking (which is a useful |
1513 | <p>Apart from keeping your process non-blocking (which is a useful |
736 | effect on its own sometimes), idle watchers are a good place to do |
1514 | effect on its own sometimes), idle watchers are a good place to do |
737 | "pseudo-background processing", or delay processing stuff to after the |
1515 | "pseudo-background processing", or delay processing stuff to after the |
738 | event loop has handled all outstanding events.</p> |
1516 | event loop has handled all outstanding events.</p> |
|
|
1517 | |
|
|
1518 | </div> |
|
|
1519 | <h3 id="Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</h3> |
|
|
1520 | <div id="Watcher_Specific_Functions_and_Data_-2-5"> |
739 | <dl> |
1521 | <dl> |
740 | <dt>ev_idle_init (ev_signal *, callback)</dt> |
1522 | <dt>ev_idle_init (ev_signal *, callback)</dt> |
741 | <dd> |
1523 | <dd> |
742 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1524 | <p>Initialises and configures the idle watcher - it has no parameters of any |
743 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1525 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
744 | believe me.</p> |
1526 | believe me.</p> |
745 | </dd> |
1527 | </dd> |
746 | </dl> |
1528 | </dl> |
|
|
1529 | <p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the |
|
|
1530 | callback, free it. Also, use no error checking, as usual.</p> |
|
|
1531 | <pre> static void |
|
|
1532 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1533 | { |
|
|
1534 | free (w); |
|
|
1535 | // now do something you wanted to do when the program has |
|
|
1536 | // no longer asnything immediate to do. |
|
|
1537 | } |
747 | |
1538 | |
|
|
1539 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1540 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1541 | ev_idle_start (loop, idle_cb); |
|
|
1542 | |
|
|
1543 | |
|
|
1544 | |
|
|
1545 | |
|
|
1546 | </pre> |
|
|
1547 | |
748 | </div> |
1548 | </div> |
749 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
1549 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2> |
750 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1550 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
751 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1551 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
752 | prepare watchers get invoked before the process blocks and check watchers |
1552 | prepare watchers get invoked before the process blocks and check watchers |
753 | afterwards.</p> |
1553 | afterwards.</p> |
|
|
1554 | <p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter |
|
|
1555 | the current event loop from either <code>ev_prepare</code> or <code>ev_check</code> |
|
|
1556 | watchers. Other loops than the current one are fine, however. The |
|
|
1557 | rationale behind this is that you do not need to check for recursion in |
|
|
1558 | those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking, |
|
|
1559 | <code>ev_check</code> so if you have one watcher of each kind they will always be |
|
|
1560 | called in pairs bracketing the blocking call.</p> |
754 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
1561 | <p>Their main purpose is to integrate other event mechanisms into libev and |
755 | could be used, for example, to track variable changes, implement your own |
1562 | their use is somewhat advanced. This could be used, for example, to track |
756 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
1563 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1564 | coroutine library and lots more. They are also occasionally useful if |
|
|
1565 | you cache some data and want to flush it before blocking (for example, |
|
|
1566 | in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code> |
|
|
1567 | watcher).</p> |
757 | <p>This is done by examining in each prepare call which file descriptors need |
1568 | <p>This is done by examining in each prepare call which file descriptors need |
758 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1569 | to be watched by the other library, registering <code>ev_io</code> watchers for |
759 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1570 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
760 | provide just this functionality). Then, in the check watcher you check for |
1571 | provide just this functionality). Then, in the check watcher you check for |
761 | any events that occured (by checking the pending status of all watchers |
1572 | any events that occured (by checking the pending status of all watchers |
… | |
… | |
768 | are ready to run (it's actually more complicated: it only runs coroutines |
1579 | are ready to run (it's actually more complicated: it only runs coroutines |
769 | with priority higher than or equal to the event loop and one coroutine |
1580 | with priority higher than or equal to the event loop and one coroutine |
770 | of lower priority, but only once, using idle watchers to keep the event |
1581 | of lower priority, but only once, using idle watchers to keep the event |
771 | loop from blocking if lower-priority coroutines are active, thus mapping |
1582 | loop from blocking if lower-priority coroutines are active, thus mapping |
772 | low-priority coroutines to idle/background tasks).</p> |
1583 | low-priority coroutines to idle/background tasks).</p> |
|
|
1584 | <p>It is recommended to give <code>ev_check</code> watchers highest (<code>EV_MAXPRI</code>) |
|
|
1585 | priority, to ensure that they are being run before any other watchers |
|
|
1586 | after the poll. Also, <code>ev_check</code> watchers (and <code>ev_prepare</code> watchers, |
|
|
1587 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1588 | supports this, they will be called before other <code>ev_check</code> watchers did |
|
|
1589 | their job. As <code>ev_check</code> watchers are often used to embed other event |
|
|
1590 | loops those other event loops might be in an unusable state until their |
|
|
1591 | <code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with |
|
|
1592 | others).</p> |
|
|
1593 | |
|
|
1594 | </div> |
|
|
1595 | <h3 id="Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</h3> |
|
|
1596 | <div id="Watcher_Specific_Functions_and_Data_-2-6"> |
773 | <dl> |
1597 | <dl> |
774 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1598 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
775 | <dt>ev_check_init (ev_check *, callback)</dt> |
1599 | <dt>ev_check_init (ev_check *, callback)</dt> |
776 | <dd> |
1600 | <dd> |
777 | <p>Initialises and configures the prepare or check watcher - they have no |
1601 | <p>Initialises and configures the prepare or check watcher - they have no |
778 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1602 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
779 | macros, but using them is utterly, utterly and completely pointless.</p> |
1603 | macros, but using them is utterly, utterly and completely pointless.</p> |
780 | </dd> |
1604 | </dd> |
781 | </dl> |
1605 | </dl> |
|
|
1606 | <p>There are a number of principal ways to embed other event loops or modules |
|
|
1607 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1608 | (there is a Perl module named <code>EV::ADNS</code> that does this, which you could |
|
|
1609 | use for an actually working example. Another Perl module named <code>EV::Glib</code> |
|
|
1610 | embeds a Glib main context into libev, and finally, <code>Glib::EV</code> embeds EV |
|
|
1611 | into the Glib event loop).</p> |
|
|
1612 | <p>Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
|
|
1613 | and in a check watcher, destroy them and call into libadns. What follows |
|
|
1614 | is pseudo-code only of course. This requires you to either use a low |
|
|
1615 | priority for the check watcher or use <code>ev_clear_pending</code> explicitly, as |
|
|
1616 | the callbacks for the IO/timeout watchers might not have been called yet.</p> |
|
|
1617 | <pre> static ev_io iow [nfd]; |
|
|
1618 | static ev_timer tw; |
782 | |
1619 | |
|
|
1620 | static void |
|
|
1621 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1622 | { |
|
|
1623 | } |
|
|
1624 | |
|
|
1625 | // create io watchers for each fd and a timer before blocking |
|
|
1626 | static void |
|
|
1627 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1628 | { |
|
|
1629 | int timeout = 3600000; |
|
|
1630 | struct pollfd fds [nfd]; |
|
|
1631 | // actual code will need to loop here and realloc etc. |
|
|
1632 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1633 | |
|
|
1634 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1635 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1636 | ev_timer_start (loop, &tw); |
|
|
1637 | |
|
|
1638 | // create one ev_io per pollfd |
|
|
1639 | for (int i = 0; i < nfd; ++i) |
|
|
1640 | { |
|
|
1641 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1642 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1643 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1644 | |
|
|
1645 | fds [i].revents = 0; |
|
|
1646 | ev_io_start (loop, iow + i); |
|
|
1647 | } |
|
|
1648 | } |
|
|
1649 | |
|
|
1650 | // stop all watchers after blocking |
|
|
1651 | static void |
|
|
1652 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1653 | { |
|
|
1654 | ev_timer_stop (loop, &tw); |
|
|
1655 | |
|
|
1656 | for (int i = 0; i < nfd; ++i) |
|
|
1657 | { |
|
|
1658 | // set the relevant poll flags |
|
|
1659 | // could also call adns_processreadable etc. here |
|
|
1660 | struct pollfd *fd = fds + i; |
|
|
1661 | int revents = ev_clear_pending (iow + i); |
|
|
1662 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1663 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1664 | |
|
|
1665 | // now stop the watcher |
|
|
1666 | ev_io_stop (loop, iow + i); |
|
|
1667 | } |
|
|
1668 | |
|
|
1669 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1670 | } |
|
|
1671 | |
|
|
1672 | </pre> |
|
|
1673 | <p>Method 2: This would be just like method 1, but you run <code>adns_afterpoll</code> |
|
|
1674 | in the prepare watcher and would dispose of the check watcher.</p> |
|
|
1675 | <p>Method 3: If the module to be embedded supports explicit event |
|
|
1676 | notification (adns does), you can also make use of the actual watcher |
|
|
1677 | callbacks, and only destroy/create the watchers in the prepare watcher.</p> |
|
|
1678 | <pre> static void |
|
|
1679 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1680 | { |
|
|
1681 | adns_state ads = (adns_state)w->data; |
|
|
1682 | update_now (EV_A); |
|
|
1683 | |
|
|
1684 | adns_processtimeouts (ads, &tv_now); |
|
|
1685 | } |
|
|
1686 | |
|
|
1687 | static void |
|
|
1688 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1689 | { |
|
|
1690 | adns_state ads = (adns_state)w->data; |
|
|
1691 | update_now (EV_A); |
|
|
1692 | |
|
|
1693 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1694 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1695 | } |
|
|
1696 | |
|
|
1697 | // do not ever call adns_afterpoll |
|
|
1698 | |
|
|
1699 | </pre> |
|
|
1700 | <p>Method 4: Do not use a prepare or check watcher because the module you |
|
|
1701 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1702 | their poll function. The drawback with this solution is that the main |
|
|
1703 | loop is now no longer controllable by EV. The <code>Glib::EV</code> module does |
|
|
1704 | this.</p> |
|
|
1705 | <pre> static gint |
|
|
1706 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1707 | { |
|
|
1708 | int got_events = 0; |
|
|
1709 | |
|
|
1710 | for (n = 0; n < nfds; ++n) |
|
|
1711 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1712 | |
|
|
1713 | if (timeout >= 0) |
|
|
1714 | // create/start timer |
|
|
1715 | |
|
|
1716 | // poll |
|
|
1717 | ev_loop (EV_A_ 0); |
|
|
1718 | |
|
|
1719 | // stop timer again |
|
|
1720 | if (timeout >= 0) |
|
|
1721 | ev_timer_stop (EV_A_ &to); |
|
|
1722 | |
|
|
1723 | // stop io watchers again - their callbacks should have set |
|
|
1724 | for (n = 0; n < nfds; ++n) |
|
|
1725 | ev_io_stop (EV_A_ iow [n]); |
|
|
1726 | |
|
|
1727 | return got_events; |
|
|
1728 | } |
|
|
1729 | |
|
|
1730 | |
|
|
1731 | |
|
|
1732 | |
|
|
1733 | </pre> |
|
|
1734 | |
783 | </div> |
1735 | </div> |
784 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1736 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2> |
|
|
1737 | <div id="code_ev_embed_code_when_one_backend_-2"> |
|
|
1738 | <p>This is a rather advanced watcher type that lets you embed one event loop |
|
|
1739 | into another (currently only <code>ev_io</code> events are supported in the embedded |
|
|
1740 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1741 | fashion and must not be used).</p> |
|
|
1742 | <p>There are primarily two reasons you would want that: work around bugs and |
|
|
1743 | prioritise I/O.</p> |
|
|
1744 | <p>As an example for a bug workaround, the kqueue backend might only support |
|
|
1745 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1746 | still want to make use of it because you have many sockets and it scales |
|
|
1747 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1748 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1749 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1750 | at least you can use both at what they are best.</p> |
|
|
1751 | <p>As for prioritising I/O: rarely you have the case where some fds have |
|
|
1752 | to be watched and handled very quickly (with low latency), and even |
|
|
1753 | priorities and idle watchers might have too much overhead. In this case |
|
|
1754 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1755 | a second one, and embed the second one in the first.</p> |
|
|
1756 | <p>As long as the watcher is active, the callback will be invoked every time |
|
|
1757 | there might be events pending in the embedded loop. The callback must then |
|
|
1758 | call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke |
|
|
1759 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1760 | loop strictly lower priority for example). You can also set the callback |
|
|
1761 | to <code>0</code>, in which case the embed watcher will automatically execute the |
|
|
1762 | embedded loop sweep.</p> |
|
|
1763 | <p>As long as the watcher is started it will automatically handle events. The |
|
|
1764 | callback will be invoked whenever some events have been handled. You can |
|
|
1765 | set the callback to <code>0</code> to avoid having to specify one if you are not |
|
|
1766 | interested in that.</p> |
|
|
1767 | <p>Also, there have not currently been made special provisions for forking: |
|
|
1768 | when you fork, you not only have to call <code>ev_loop_fork</code> on both loops, |
|
|
1769 | but you will also have to stop and restart any <code>ev_embed</code> watchers |
|
|
1770 | yourself.</p> |
|
|
1771 | <p>Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1772 | <code>ev_embeddable_backends</code> are, which, unfortunately, does not include any |
|
|
1773 | portable one.</p> |
|
|
1774 | <p>So when you want to use this feature you will always have to be prepared |
|
|
1775 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1776 | this is to have a separate variables for your embeddable loop, try to |
|
|
1777 | create it, and if that fails, use the normal loop for everything:</p> |
|
|
1778 | <pre> struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1779 | struct ev_loop *loop_lo = 0; |
|
|
1780 | struct ev_embed embed; |
|
|
1781 | |
|
|
1782 | // see if there is a chance of getting one that works |
|
|
1783 | // (remember that a flags value of 0 means autodetection) |
|
|
1784 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1785 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1786 | : 0; |
|
|
1787 | |
|
|
1788 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1789 | if (loop_lo) |
|
|
1790 | { |
|
|
1791 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1792 | ev_embed_start (loop_hi, &embed); |
|
|
1793 | } |
|
|
1794 | else |
|
|
1795 | loop_lo = loop_hi; |
|
|
1796 | |
|
|
1797 | </pre> |
|
|
1798 | |
|
|
1799 | </div> |
|
|
1800 | <h3 id="Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</h3> |
|
|
1801 | <div id="Watcher_Specific_Functions_and_Data_-2-7"> |
|
|
1802 | <dl> |
|
|
1803 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1804 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1805 | <dd> |
|
|
1806 | <p>Configures the watcher to embed the given loop, which must be |
|
|
1807 | embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be |
|
|
1808 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1809 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1810 | if you do not want thta, you need to temporarily stop the embed watcher).</p> |
|
|
1811 | </dd> |
|
|
1812 | <dt>ev_embed_sweep (loop, ev_embed *)</dt> |
|
|
1813 | <dd> |
|
|
1814 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1815 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
|
|
1816 | apropriate way for embedded loops.</p> |
|
|
1817 | </dd> |
|
|
1818 | <dt>struct ev_loop *loop [read-only]</dt> |
|
|
1819 | <dd> |
|
|
1820 | <p>The embedded event loop.</p> |
|
|
1821 | </dd> |
|
|
1822 | </dl> |
|
|
1823 | |
|
|
1824 | |
|
|
1825 | |
|
|
1826 | |
|
|
1827 | |
|
|
1828 | </div> |
|
|
1829 | <h2 id="code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</h2> |
|
|
1830 | <div id="code_ev_fork_code_the_audacity_to_re-2"> |
|
|
1831 | <p>Fork watchers are called when a <code>fork ()</code> was detected (usually because |
|
|
1832 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1833 | <code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the |
|
|
1834 | event loop blocks next and before <code>ev_check</code> watchers are being called, |
|
|
1835 | and only in the child after the fork. If whoever good citizen calling |
|
|
1836 | <code>ev_default_fork</code> cheats and calls it in the wrong process, the fork |
|
|
1837 | handlers will be invoked, too, of course.</p> |
|
|
1838 | |
|
|
1839 | </div> |
|
|
1840 | <h3 id="Watcher_Specific_Functions_and_Data_-10">Watcher-Specific Functions and Data Members</h3> |
|
|
1841 | <div id="Watcher_Specific_Functions_and_Data_-2-8"> |
|
|
1842 | <dl> |
|
|
1843 | <dt>ev_fork_init (ev_signal *, callback)</dt> |
|
|
1844 | <dd> |
|
|
1845 | <p>Initialises and configures the fork watcher - it has no parameters of any |
|
|
1846 | kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless, |
|
|
1847 | believe me.</p> |
|
|
1848 | </dd> |
|
|
1849 | </dl> |
|
|
1850 | |
|
|
1851 | |
|
|
1852 | |
|
|
1853 | |
|
|
1854 | |
|
|
1855 | </div> |
|
|
1856 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1> |
785 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1857 | <div id="OTHER_FUNCTIONS_CONTENT"> |
786 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1858 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
787 | <dl> |
1859 | <dl> |
788 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1860 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
789 | <dd> |
1861 | <dd> |
… | |
… | |
813 | |
1885 | |
814 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1886 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
815 | |
1887 | |
816 | </pre> |
1888 | </pre> |
817 | </dd> |
1889 | </dd> |
818 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
1890 | <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt> |
819 | <dd> |
1891 | <dd> |
820 | <p>Feeds the given event set into the event loop, as if the specified event |
1892 | <p>Feeds the given event set into the event loop, as if the specified event |
821 | had happened for the specified watcher (which must be a pointer to an |
1893 | had happened for the specified watcher (which must be a pointer to an |
822 | initialised but not necessarily started event watcher).</p> |
1894 | initialised but not necessarily started event watcher).</p> |
823 | </dd> |
1895 | </dd> |
824 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
1896 | <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt> |
825 | <dd> |
1897 | <dd> |
826 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
1898 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
827 | the given events it.</p> |
1899 | the given events it.</p> |
828 | </dd> |
1900 | </dd> |
829 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
1901 | <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt> |
830 | <dd> |
1902 | <dd> |
831 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
1903 | <p>Feed an event as if the given signal occured (<code>loop</code> must be the default |
|
|
1904 | loop!).</p> |
832 | </dd> |
1905 | </dd> |
833 | </dl> |
1906 | </dl> |
834 | |
1907 | |
|
|
1908 | |
|
|
1909 | |
|
|
1910 | |
|
|
1911 | |
835 | </div> |
1912 | </div> |
836 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1913 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1> |
837 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1914 | <div id="LIBEVENT_EMULATION_CONTENT"> |
838 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1915 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
839 | emulate the internals of libevent, so here are some usage hints:</p> |
1916 | emulate the internals of libevent, so here are some usage hints:</p> |
840 | <dl> |
1917 | <dl> |
841 | <dt>* Use it by including <event.h>, as usual.</dt> |
1918 | <dt>* Use it by including <event.h>, as usual.</dt> |
… | |
… | |
851 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1928 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
852 | to use the libev header file and library.</dt> |
1929 | to use the libev header file and library.</dt> |
853 | </dl> |
1930 | </dl> |
854 | |
1931 | |
855 | </div> |
1932 | </div> |
856 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1933 | <h1 id="C_SUPPORT">C++ SUPPORT</h1> |
857 | <div id="C_SUPPORT_CONTENT"> |
1934 | <div id="C_SUPPORT_CONTENT"> |
858 | <p>TBD.</p> |
1935 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1936 | you to use some convinience methods to start/stop watchers and also change |
|
|
1937 | the callback model to a model using method callbacks on objects.</p> |
|
|
1938 | <p>To use it,</p> |
|
|
1939 | <pre> #include <ev++.h> |
859 | |
1940 | |
|
|
1941 | </pre> |
|
|
1942 | <p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many |
|
|
1943 | of them macros) into the global namespace. All C++ specific things are |
|
|
1944 | put into the <code>ev</code> namespace. It should support all the same embedding |
|
|
1945 | options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p> |
|
|
1946 | <p>Care has been taken to keep the overhead low. The only data member the C++ |
|
|
1947 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1948 | that the watcher is associated with (or no additional members at all if |
|
|
1949 | you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p> |
|
|
1950 | <p>Currently, functions, and static and non-static member functions can be |
|
|
1951 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1952 | need one additional pointer for context. If you need support for other |
|
|
1953 | types of functors please contact the author (preferably after implementing |
|
|
1954 | it).</p> |
|
|
1955 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
|
|
1956 | <dl> |
|
|
1957 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
|
|
1958 | <dd> |
|
|
1959 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
|
|
1960 | macros from <cite>ev.h</cite>.</p> |
|
|
1961 | </dd> |
|
|
1962 | <dt><code>ev::tstamp</code>, <code>ev::now</code></dt> |
|
|
1963 | <dd> |
|
|
1964 | <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p> |
|
|
1965 | </dd> |
|
|
1966 | <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt> |
|
|
1967 | <dd> |
|
|
1968 | <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of |
|
|
1969 | the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code> |
|
|
1970 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
|
|
1971 | defines by many implementations.</p> |
|
|
1972 | <p>All of those classes have these methods:</p> |
|
|
1973 | <p> |
|
|
1974 | <dl> |
|
|
1975 | <dt>ev::TYPE::TYPE ()</dt> |
|
|
1976 | <dt>ev::TYPE::TYPE (struct ev_loop *)</dt> |
|
|
1977 | <dt>ev::TYPE::~TYPE</dt> |
|
|
1978 | <dd> |
|
|
1979 | <p>The constructor (optionally) takes an event loop to associate the watcher |
|
|
1980 | with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p> |
|
|
1981 | <p>The constructor calls <code>ev_init</code> for you, which means you have to call the |
|
|
1982 | <code>set</code> method before starting it.</p> |
|
|
1983 | <p>It will not set a callback, however: You have to call the templated <code>set</code> |
|
|
1984 | method to set a callback before you can start the watcher.</p> |
|
|
1985 | <p>(The reason why you have to use a method is a limitation in C++ which does |
|
|
1986 | not allow explicit template arguments for constructors).</p> |
|
|
1987 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1988 | </dd> |
|
|
1989 | <dt>w->set<class, &class::method> (object *)</dt> |
|
|
1990 | <dd> |
|
|
1991 | <p>This method sets the callback method to call. The method has to have a |
|
|
1992 | signature of <code>void (*)(ev_TYPE &, int)</code>, it receives the watcher as |
|
|
1993 | first argument and the <code>revents</code> as second. The object must be given as |
|
|
1994 | parameter and is stored in the <code>data</code> member of the watcher.</p> |
|
|
1995 | <p>This method synthesizes efficient thunking code to call your method from |
|
|
1996 | the C callback that libev requires. If your compiler can inline your |
|
|
1997 | callback (i.e. it is visible to it at the place of the <code>set</code> call and |
|
|
1998 | your compiler is good :), then the method will be fully inlined into the |
|
|
1999 | thunking function, making it as fast as a direct C callback.</p> |
|
|
2000 | <p>Example: simple class declaration and watcher initialisation</p> |
|
|
2001 | <pre> struct myclass |
|
|
2002 | { |
|
|
2003 | void io_cb (ev::io &w, int revents) { } |
|
|
2004 | } |
|
|
2005 | |
|
|
2006 | myclass obj; |
|
|
2007 | ev::io iow; |
|
|
2008 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2009 | |
|
|
2010 | </pre> |
|
|
2011 | </dd> |
|
|
2012 | <dt>w->set<function> (void *data = 0)</dt> |
|
|
2013 | <dd> |
|
|
2014 | <p>Also sets a callback, but uses a static method or plain function as |
|
|
2015 | callback. The optional <code>data</code> argument will be stored in the watcher's |
|
|
2016 | <code>data</code> member and is free for you to use.</p> |
|
|
2017 | <p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &w, int)</code>.</p> |
|
|
2018 | <p>See the method-<code>set</code> above for more details.</p> |
|
|
2019 | <p>Example:</p> |
|
|
2020 | <pre> static void io_cb (ev::io &w, int revents) { } |
|
|
2021 | iow.set <io_cb> (); |
|
|
2022 | |
|
|
2023 | </pre> |
|
|
2024 | </dd> |
|
|
2025 | <dt>w->set (struct ev_loop *)</dt> |
|
|
2026 | <dd> |
|
|
2027 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
|
|
2028 | do this when the watcher is inactive (and not pending either).</p> |
|
|
2029 | </dd> |
|
|
2030 | <dt>w->set ([args])</dt> |
|
|
2031 | <dd> |
|
|
2032 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
|
|
2033 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
2034 | automatically stopped and restarted when reconfiguring it with this |
|
|
2035 | method.</p> |
|
|
2036 | </dd> |
|
|
2037 | <dt>w->start ()</dt> |
|
|
2038 | <dd> |
|
|
2039 | <p>Starts the watcher. Note that there is no <code>loop</code> argument, as the |
|
|
2040 | constructor already stores the event loop.</p> |
|
|
2041 | </dd> |
|
|
2042 | <dt>w->stop ()</dt> |
|
|
2043 | <dd> |
|
|
2044 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
|
|
2045 | </dd> |
|
|
2046 | <dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt> |
|
|
2047 | <dd> |
|
|
2048 | <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding |
|
|
2049 | <code>ev_TYPE_again</code> function.</p> |
|
|
2050 | </dd> |
|
|
2051 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
|
|
2052 | <dd> |
|
|
2053 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
|
|
2054 | </dd> |
|
|
2055 | <dt>w->update () <code>ev::stat</code> only</dt> |
|
|
2056 | <dd> |
|
|
2057 | <p>Invokes <code>ev_stat_stat</code>.</p> |
|
|
2058 | </dd> |
|
|
2059 | </dl> |
|
|
2060 | </p> |
|
|
2061 | </dd> |
|
|
2062 | </dl> |
|
|
2063 | <p>Example: Define a class with an IO and idle watcher, start one of them in |
|
|
2064 | the constructor.</p> |
|
|
2065 | <pre> class myclass |
|
|
2066 | { |
|
|
2067 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
2068 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
2069 | |
|
|
2070 | myclass (); |
|
|
2071 | } |
|
|
2072 | |
|
|
2073 | myclass::myclass (int fd) |
|
|
2074 | { |
|
|
2075 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2076 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2077 | |
|
|
2078 | io.start (fd, ev::READ); |
|
|
2079 | } |
|
|
2080 | |
|
|
2081 | |
|
|
2082 | |
|
|
2083 | |
|
|
2084 | </pre> |
|
|
2085 | |
860 | </div> |
2086 | </div> |
861 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2087 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
|
|
2088 | <div id="MACRO_MAGIC_CONTENT"> |
|
|
2089 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
|
|
2090 | <code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and |
|
|
2091 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
|
|
2092 | <p>To make it easier to write programs that cope with either variant, the |
|
|
2093 | following macros are defined:</p> |
|
|
2094 | <dl> |
|
|
2095 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
|
|
2096 | <dd> |
|
|
2097 | <p>This provides the loop <i>argument</i> for functions, if one is required ("ev |
|
|
2098 | loop argument"). The <code>EV_A</code> form is used when this is the sole argument, |
|
|
2099 | <code>EV_A_</code> is used when other arguments are following. Example:</p> |
|
|
2100 | <pre> ev_unref (EV_A); |
|
|
2101 | ev_timer_add (EV_A_ watcher); |
|
|
2102 | ev_loop (EV_A_ 0); |
|
|
2103 | |
|
|
2104 | </pre> |
|
|
2105 | <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope, |
|
|
2106 | which is often provided by the following macro.</p> |
|
|
2107 | </dd> |
|
|
2108 | <dt><code>EV_P</code>, <code>EV_P_</code></dt> |
|
|
2109 | <dd> |
|
|
2110 | <p>This provides the loop <i>parameter</i> for functions, if one is required ("ev |
|
|
2111 | loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter, |
|
|
2112 | <code>EV_P_</code> is used when other parameters are following. Example:</p> |
|
|
2113 | <pre> // this is how ev_unref is being declared |
|
|
2114 | static void ev_unref (EV_P); |
|
|
2115 | |
|
|
2116 | // this is how you can declare your typical callback |
|
|
2117 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
2118 | |
|
|
2119 | </pre> |
|
|
2120 | <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite |
|
|
2121 | suitable for use with <code>EV_A</code>.</p> |
|
|
2122 | </dd> |
|
|
2123 | <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt> |
|
|
2124 | <dd> |
|
|
2125 | <p>Similar to the other two macros, this gives you the value of the default |
|
|
2126 | loop, if multiple loops are supported ("ev loop default").</p> |
|
|
2127 | </dd> |
|
|
2128 | </dl> |
|
|
2129 | <p>Example: Declare and initialise a check watcher, utilising the above |
|
|
2130 | macros so it will work regardless of whether multiple loops are supported |
|
|
2131 | or not.</p> |
|
|
2132 | <pre> static void |
|
|
2133 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
2134 | { |
|
|
2135 | ev_check_stop (EV_A_ w); |
|
|
2136 | } |
|
|
2137 | |
|
|
2138 | ev_check check; |
|
|
2139 | ev_check_init (&check, check_cb); |
|
|
2140 | ev_check_start (EV_DEFAULT_ &check); |
|
|
2141 | ev_loop (EV_DEFAULT_ 0); |
|
|
2142 | |
|
|
2143 | </pre> |
|
|
2144 | |
|
|
2145 | </div> |
|
|
2146 | <h1 id="EMBEDDING">EMBEDDING</h1> |
|
|
2147 | <div id="EMBEDDING_CONTENT"> |
|
|
2148 | <p>Libev can (and often is) directly embedded into host |
|
|
2149 | applications. Examples of applications that embed it include the Deliantra |
|
|
2150 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
2151 | and rxvt-unicode.</p> |
|
|
2152 | <p>The goal is to enable you to just copy the neecssary files into your |
|
|
2153 | source directory without having to change even a single line in them, so |
|
|
2154 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
2155 | libev somewhere in your source tree).</p> |
|
|
2156 | |
|
|
2157 | </div> |
|
|
2158 | <h2 id="FILESETS">FILESETS</h2> |
|
|
2159 | <div id="FILESETS_CONTENT"> |
|
|
2160 | <p>Depending on what features you need you need to include one or more sets of files |
|
|
2161 | in your app.</p> |
|
|
2162 | |
|
|
2163 | </div> |
|
|
2164 | <h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3> |
|
|
2165 | <div id="CORE_EVENT_LOOP_CONTENT"> |
|
|
2166 | <p>To include only the libev core (all the <code>ev_*</code> functions), with manual |
|
|
2167 | configuration (no autoconf):</p> |
|
|
2168 | <pre> #define EV_STANDALONE 1 |
|
|
2169 | #include "ev.c" |
|
|
2170 | |
|
|
2171 | </pre> |
|
|
2172 | <p>This will automatically include <cite>ev.h</cite>, too, and should be done in a |
|
|
2173 | single C source file only to provide the function implementations. To use |
|
|
2174 | it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best |
|
|
2175 | done by writing a wrapper around <cite>ev.h</cite> that you can include instead and |
|
|
2176 | where you can put other configuration options):</p> |
|
|
2177 | <pre> #define EV_STANDALONE 1 |
|
|
2178 | #include "ev.h" |
|
|
2179 | |
|
|
2180 | </pre> |
|
|
2181 | <p>Both header files and implementation files can be compiled with a C++ |
|
|
2182 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
2183 | as a bug).</p> |
|
|
2184 | <p>You need the following files in your source tree, or in a directory |
|
|
2185 | in your include path (e.g. in libev/ when using -Ilibev):</p> |
|
|
2186 | <pre> ev.h |
|
|
2187 | ev.c |
|
|
2188 | ev_vars.h |
|
|
2189 | ev_wrap.h |
|
|
2190 | |
|
|
2191 | ev_win32.c required on win32 platforms only |
|
|
2192 | |
|
|
2193 | ev_select.c only when select backend is enabled (which is enabled by default) |
|
|
2194 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
2195 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
2196 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
2197 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
2198 | |
|
|
2199 | </pre> |
|
|
2200 | <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need |
|
|
2201 | to compile this single file.</p> |
|
|
2202 | |
|
|
2203 | </div> |
|
|
2204 | <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> |
|
|
2205 | <div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> |
|
|
2206 | <p>To include the libevent compatibility API, also include:</p> |
|
|
2207 | <pre> #include "event.c" |
|
|
2208 | |
|
|
2209 | </pre> |
|
|
2210 | <p>in the file including <cite>ev.c</cite>, and:</p> |
|
|
2211 | <pre> #include "event.h" |
|
|
2212 | |
|
|
2213 | </pre> |
|
|
2214 | <p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p> |
|
|
2215 | <p>You need the following additional files for this:</p> |
|
|
2216 | <pre> event.h |
|
|
2217 | event.c |
|
|
2218 | |
|
|
2219 | </pre> |
|
|
2220 | |
|
|
2221 | </div> |
|
|
2222 | <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> |
|
|
2223 | <div id="AUTOCONF_SUPPORT_CONTENT"> |
|
|
2224 | <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in |
|
|
2225 | whatever way you want, you can also <code>m4_include([libev.m4])</code> in your |
|
|
2226 | <cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then |
|
|
2227 | include <cite>config.h</cite> and configure itself accordingly.</p> |
|
|
2228 | <p>For this of course you need the m4 file:</p> |
|
|
2229 | <pre> libev.m4 |
|
|
2230 | |
|
|
2231 | </pre> |
|
|
2232 | |
|
|
2233 | </div> |
|
|
2234 | <h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2> |
|
|
2235 | <div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT"> |
|
|
2236 | <p>Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
2237 | before including any of its files. The default is not to build for multiplicity |
|
|
2238 | and only include the select backend.</p> |
|
|
2239 | <dl> |
|
|
2240 | <dt>EV_STANDALONE</dt> |
|
|
2241 | <dd> |
|
|
2242 | <p>Must always be <code>1</code> if you do not use autoconf configuration, which |
|
|
2243 | keeps libev from including <cite>config.h</cite>, and it also defines dummy |
|
|
2244 | implementations for some libevent functions (such as logging, which is not |
|
|
2245 | supported). It will also not define any of the structs usually found in |
|
|
2246 | <cite>event.h</cite> that are not directly supported by the libev core alone.</p> |
|
|
2247 | </dd> |
|
|
2248 | <dt>EV_USE_MONOTONIC</dt> |
|
|
2249 | <dd> |
|
|
2250 | <p>If defined to be <code>1</code>, libev will try to detect the availability of the |
|
|
2251 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
2252 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
2253 | usually have to link against librt or something similar. Enabling it when |
|
|
2254 | the functionality isn't available is safe, though, althoguh you have |
|
|
2255 | to make sure you link against any libraries where the <code>clock_gettime</code> |
|
|
2256 | function is hiding in (often <cite>-lrt</cite>).</p> |
|
|
2257 | </dd> |
|
|
2258 | <dt>EV_USE_REALTIME</dt> |
|
|
2259 | <dd> |
|
|
2260 | <p>If defined to be <code>1</code>, libev will try to detect the availability of the |
|
|
2261 | realtime clock option at compiletime (and assume its availability at |
|
|
2262 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
2263 | be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get |
|
|
2264 | (CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries |
|
|
2265 | in the description of <code>EV_USE_MONOTONIC</code>, though.</p> |
|
|
2266 | </dd> |
|
|
2267 | <dt>EV_USE_SELECT</dt> |
|
|
2268 | <dd> |
|
|
2269 | <p>If undefined or defined to be <code>1</code>, libev will compile in support for the |
|
|
2270 | <code>select</code>(2) backend. No attempt at autodetection will be done: if no |
|
|
2271 | other method takes over, select will be it. Otherwise the select backend |
|
|
2272 | will not be compiled in.</p> |
|
|
2273 | </dd> |
|
|
2274 | <dt>EV_SELECT_USE_FD_SET</dt> |
|
|
2275 | <dd> |
|
|
2276 | <p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code> |
|
|
2277 | structure. This is useful if libev doesn't compile due to a missing |
|
|
2278 | <code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on |
|
|
2279 | exotic systems. This usually limits the range of file descriptors to some |
|
|
2280 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
2281 | allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might |
|
|
2282 | influence the size of the <code>fd_set</code> used.</p> |
|
|
2283 | </dd> |
|
|
2284 | <dt>EV_SELECT_IS_WINSOCKET</dt> |
|
|
2285 | <dd> |
|
|
2286 | <p>When defined to <code>1</code>, the select backend will assume that |
|
|
2287 | select/socket/connect etc. don't understand file descriptors but |
|
|
2288 | wants osf handles on win32 (this is the case when the select to |
|
|
2289 | be used is the winsock select). This means that it will call |
|
|
2290 | <code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise, |
|
|
2291 | it is assumed that all these functions actually work on fds, even |
|
|
2292 | on win32. Should not be defined on non-win32 platforms.</p> |
|
|
2293 | </dd> |
|
|
2294 | <dt>EV_USE_POLL</dt> |
|
|
2295 | <dd> |
|
|
2296 | <p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2) |
|
|
2297 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
2298 | takes precedence over select.</p> |
|
|
2299 | </dd> |
|
|
2300 | <dt>EV_USE_EPOLL</dt> |
|
|
2301 | <dd> |
|
|
2302 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux |
|
|
2303 | <code>epoll</code>(7) backend. Its availability will be detected at runtime, |
|
|
2304 | otherwise another method will be used as fallback. This is the |
|
|
2305 | preferred backend for GNU/Linux systems.</p> |
|
|
2306 | </dd> |
|
|
2307 | <dt>EV_USE_KQUEUE</dt> |
|
|
2308 | <dd> |
|
|
2309 | <p>If defined to be <code>1</code>, libev will compile in support for the BSD style |
|
|
2310 | <code>kqueue</code>(2) backend. Its actual availability will be detected at runtime, |
|
|
2311 | otherwise another method will be used as fallback. This is the preferred |
|
|
2312 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
2313 | supports some types of fds correctly (the only platform we found that |
|
|
2314 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
2315 | not be used unless explicitly requested. The best way to use it is to find |
|
|
2316 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
2317 | kqueue loop.</p> |
|
|
2318 | </dd> |
|
|
2319 | <dt>EV_USE_PORT</dt> |
|
|
2320 | <dd> |
|
|
2321 | <p>If defined to be <code>1</code>, libev will compile in support for the Solaris |
|
|
2322 | 10 port style backend. Its availability will be detected at runtime, |
|
|
2323 | otherwise another method will be used as fallback. This is the preferred |
|
|
2324 | backend for Solaris 10 systems.</p> |
|
|
2325 | </dd> |
|
|
2326 | <dt>EV_USE_DEVPOLL</dt> |
|
|
2327 | <dd> |
|
|
2328 | <p>reserved for future expansion, works like the USE symbols above.</p> |
|
|
2329 | </dd> |
|
|
2330 | <dt>EV_USE_INOTIFY</dt> |
|
|
2331 | <dd> |
|
|
2332 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify |
|
|
2333 | interface to speed up <code>ev_stat</code> watchers. Its actual availability will |
|
|
2334 | be detected at runtime.</p> |
|
|
2335 | </dd> |
|
|
2336 | <dt>EV_H</dt> |
|
|
2337 | <dd> |
|
|
2338 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
|
|
2339 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
|
|
2340 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
|
|
2341 | </dd> |
|
|
2342 | <dt>EV_CONFIG_H</dt> |
|
|
2343 | <dd> |
|
|
2344 | <p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override |
|
|
2345 | <cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to |
|
|
2346 | <code>EV_H</code>, above.</p> |
|
|
2347 | </dd> |
|
|
2348 | <dt>EV_EVENT_H</dt> |
|
|
2349 | <dd> |
|
|
2350 | <p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea |
|
|
2351 | of how the <cite>event.h</cite> header can be found.</p> |
|
|
2352 | </dd> |
|
|
2353 | <dt>EV_PROTOTYPES</dt> |
|
|
2354 | <dd> |
|
|
2355 | <p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function |
|
|
2356 | prototypes, but still define all the structs and other symbols. This is |
|
|
2357 | occasionally useful if you want to provide your own wrapper functions |
|
|
2358 | around libev functions.</p> |
|
|
2359 | </dd> |
|
|
2360 | <dt>EV_MULTIPLICITY</dt> |
|
|
2361 | <dd> |
|
|
2362 | <p>If undefined or defined to <code>1</code>, then all event-loop-specific functions |
|
|
2363 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
|
|
2364 | additional independent event loops. Otherwise there will be no support |
|
|
2365 | for multiple event loops and there is no first event loop pointer |
|
|
2366 | argument. Instead, all functions act on the single default loop.</p> |
|
|
2367 | </dd> |
|
|
2368 | <dt>EV_MINPRI</dt> |
|
|
2369 | <dt>EV_MAXPRI</dt> |
|
|
2370 | <dd> |
|
|
2371 | <p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to |
|
|
2372 | <code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can |
|
|
2373 | provide for more priorities by overriding those symbols (usually defined |
|
|
2374 | to be <code>-2</code> and <code>2</code>, respectively).</p> |
|
|
2375 | <p>When doing priority-based operations, libev usually has to linearly search |
|
|
2376 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2377 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2378 | fine.</p> |
|
|
2379 | <p>If your embedding app does not need any priorities, defining these both to |
|
|
2380 | <code>0</code> will save some memory and cpu.</p> |
|
|
2381 | </dd> |
|
|
2382 | <dt>EV_PERIODIC_ENABLE</dt> |
|
|
2383 | <dd> |
|
|
2384 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
|
|
2385 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2386 | code.</p> |
|
|
2387 | </dd> |
|
|
2388 | <dt>EV_IDLE_ENABLE</dt> |
|
|
2389 | <dd> |
|
|
2390 | <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If |
|
|
2391 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2392 | code.</p> |
|
|
2393 | </dd> |
|
|
2394 | <dt>EV_EMBED_ENABLE</dt> |
|
|
2395 | <dd> |
|
|
2396 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
|
|
2397 | defined to be <code>0</code>, then they are not.</p> |
|
|
2398 | </dd> |
|
|
2399 | <dt>EV_STAT_ENABLE</dt> |
|
|
2400 | <dd> |
|
|
2401 | <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If |
|
|
2402 | defined to be <code>0</code>, then they are not.</p> |
|
|
2403 | </dd> |
|
|
2404 | <dt>EV_FORK_ENABLE</dt> |
|
|
2405 | <dd> |
|
|
2406 | <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If |
|
|
2407 | defined to be <code>0</code>, then they are not.</p> |
|
|
2408 | </dd> |
|
|
2409 | <dt>EV_MINIMAL</dt> |
|
|
2410 | <dd> |
|
|
2411 | <p>If you need to shave off some kilobytes of code at the expense of some |
|
|
2412 | speed, define this symbol to <code>1</code>. Currently only used for gcc to override |
|
|
2413 | some inlining decisions, saves roughly 30% codesize of amd64.</p> |
|
|
2414 | </dd> |
|
|
2415 | <dt>EV_PID_HASHSIZE</dt> |
|
|
2416 | <dd> |
|
|
2417 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
|
|
2418 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
|
|
2419 | than enough. If you need to manage thousands of children you might want to |
|
|
2420 | increase this value (<i>must</i> be a power of two).</p> |
|
|
2421 | </dd> |
|
|
2422 | <dt>EV_INOTIFY_HASHSIZE</dt> |
|
|
2423 | <dd> |
|
|
2424 | <p><code>ev_staz</code> watchers use a small hash table to distribute workload by |
|
|
2425 | inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), |
|
|
2426 | usually more than enough. If you need to manage thousands of <code>ev_stat</code> |
|
|
2427 | watchers you might want to increase this value (<i>must</i> be a power of |
|
|
2428 | two).</p> |
|
|
2429 | </dd> |
|
|
2430 | <dt>EV_COMMON</dt> |
|
|
2431 | <dd> |
|
|
2432 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
|
|
2433 | this macro to a something else you can include more and other types of |
|
|
2434 | members. You have to define it each time you include one of the files, |
|
|
2435 | though, and it must be identical each time.</p> |
|
|
2436 | <p>For example, the perl EV module uses something like this:</p> |
|
|
2437 | <pre> #define EV_COMMON \ |
|
|
2438 | SV *self; /* contains this struct */ \ |
|
|
2439 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2440 | |
|
|
2441 | </pre> |
|
|
2442 | </dd> |
|
|
2443 | <dt>EV_CB_DECLARE (type)</dt> |
|
|
2444 | <dt>EV_CB_INVOKE (watcher, revents)</dt> |
|
|
2445 | <dt>ev_set_cb (ev, cb)</dt> |
|
|
2446 | <dd> |
|
|
2447 | <p>Can be used to change the callback member declaration in each watcher, |
|
|
2448 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2449 | definition and a statement, respectively. See the <cite>ev.v</cite> header file for |
|
|
2450 | their default definitions. One possible use for overriding these is to |
|
|
2451 | avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use |
|
|
2452 | method calls instead of plain function calls in C++.</p> |
|
|
2453 | |
|
|
2454 | </div> |
|
|
2455 | <h2 id="EXAMPLES">EXAMPLES</h2> |
|
|
2456 | <div id="EXAMPLES_CONTENT"> |
|
|
2457 | <p>For a real-world example of a program the includes libev |
|
|
2458 | verbatim, you can have a look at the EV perl module |
|
|
2459 | (<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in |
|
|
2460 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
|
|
2461 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
|
|
2462 | will be compiled. It is pretty complex because it provides its own header |
|
|
2463 | file.</p> |
|
|
2464 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
|
|
2465 | that everybody includes and which overrides some configure choices:</p> |
|
|
2466 | <pre> #define EV_MINIMAL 1 |
|
|
2467 | #define EV_USE_POLL 0 |
|
|
2468 | #define EV_MULTIPLICITY 0 |
|
|
2469 | #define EV_PERIODIC_ENABLE 0 |
|
|
2470 | #define EV_STAT_ENABLE 0 |
|
|
2471 | #define EV_FORK_ENABLE 0 |
|
|
2472 | #define EV_CONFIG_H <config.h> |
|
|
2473 | #define EV_MINPRI 0 |
|
|
2474 | #define EV_MAXPRI 0 |
|
|
2475 | |
|
|
2476 | #include "ev++.h" |
|
|
2477 | |
|
|
2478 | </pre> |
|
|
2479 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
|
|
2480 | <pre> #include "ev_cpp.h" |
|
|
2481 | #include "ev.c" |
|
|
2482 | |
|
|
2483 | |
|
|
2484 | |
|
|
2485 | |
|
|
2486 | </pre> |
|
|
2487 | |
|
|
2488 | </div> |
|
|
2489 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
|
|
2490 | <div id="COMPLEXITIES_CONTENT"> |
|
|
2491 | <p>In this section the complexities of (many of) the algorithms used inside |
|
|
2492 | libev will be explained. For complexity discussions about backends see the |
|
|
2493 | documentation for <code>ev_default_init</code>.</p> |
|
|
2494 | <p>All of the following are about amortised time: If an array needs to be |
|
|
2495 | extended, libev needs to realloc and move the whole array, but this |
|
|
2496 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2497 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2498 | it is much faster and asymptotically approaches constant time.</p> |
|
|
2499 | <p> |
|
|
2500 | <dl> |
|
|
2501 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
2502 | <dd> |
|
|
2503 | <p>This means that, when you have a watcher that triggers in one hour and |
|
|
2504 | there are 100 watchers that would trigger before that then inserting will |
|
|
2505 | have to skip those 100 watchers.</p> |
|
|
2506 | </dd> |
|
|
2507 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
2508 | <dd> |
|
|
2509 | <p>That means that for changing a timer costs less than removing/adding them |
|
|
2510 | as only the relative motion in the event queue has to be paid for.</p> |
|
|
2511 | </dd> |
|
|
2512 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
2513 | <dd> |
|
|
2514 | <p>These just add the watcher into an array or at the head of a list. |
|
|
2515 | =item Stopping check/prepare/idle watchers: O(1)</p> |
|
|
2516 | </dd> |
|
|
2517 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
|
|
2518 | <dd> |
|
|
2519 | <p>These watchers are stored in lists then need to be walked to find the |
|
|
2520 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2521 | have many watchers waiting for the same fd or signal).</p> |
|
|
2522 | </dd> |
|
|
2523 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
|
|
2524 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
2525 | <dd> |
|
|
2526 | <p>A change means an I/O watcher gets started or stopped, which requires |
|
|
2527 | libev to recalculate its status (and possibly tell the kernel).</p> |
|
|
2528 | </dd> |
|
|
2529 | <dt>Activating one watcher: O(1)</dt> |
|
|
2530 | <dt>Priority handling: O(number_of_priorities)</dt> |
|
|
2531 | <dd> |
|
|
2532 | <p>Priorities are implemented by allocating some space for each |
|
|
2533 | priority. When doing priority-based operations, libev usually has to |
|
|
2534 | linearly search all the priorities.</p> |
|
|
2535 | </dd> |
|
|
2536 | </dl> |
|
|
2537 | </p> |
|
|
2538 | |
|
|
2539 | |
|
|
2540 | |
|
|
2541 | |
|
|
2542 | |
|
|
2543 | </div> |
|
|
2544 | <h1 id="AUTHOR">AUTHOR</h1> |
862 | <div id="AUTHOR_CONTENT"> |
2545 | <div id="AUTHOR_CONTENT"> |
863 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2546 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
864 | |
2547 | |
865 | </div> |
2548 | </div> |
866 | </div></body> |
2549 | </div></body> |
867 | </html> |
2550 | </html> |