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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> |
12 | <body> |
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> |
26 | <ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li> |
27 | <ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li> |
27 | <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> |
28 | </ul> |
29 | </ul> |
29 | </li> |
30 | </li> |
30 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
31 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
31 | <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></li> |
32 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
33 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
33 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> |
34 | <li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> |
34 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
35 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> |
35 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
36 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> |
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37 | <li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li> |
36 | <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> |
38 | <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> |
37 | <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> |
39 | <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> |
38 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</a></li> |
40 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> |
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41 | <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></li> |
39 | </ul> |
42 | </ul> |
40 | </li> |
43 | </li> |
41 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
44 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
42 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
45 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
43 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
46 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
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47 | <li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li> |
44 | <li><a href="#EMBEDDING">EMBEDDING</a> |
48 | <li><a href="#EMBEDDING">EMBEDDING</a> |
45 | <ul><li><a href="#FILESETS">FILESETS</a> |
49 | <ul><li><a href="#FILESETS">FILESETS</a> |
46 | <ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li> |
50 | <ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li> |
47 | <li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> |
51 | <li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> |
48 | <li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> |
52 | <li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> |
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50 | </li> |
54 | </li> |
51 | <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> |
55 | <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> |
52 | <li><a href="#EXAMPLES">EXAMPLES</a></li> |
56 | <li><a href="#EXAMPLES">EXAMPLES</a></li> |
53 | </ul> |
57 | </ul> |
54 | </li> |
58 | </li> |
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59 | <li><a href="#COMPLEXITIES">COMPLEXITIES</a></li> |
55 | <li><a href="#AUTHOR">AUTHOR</a> |
60 | <li><a href="#AUTHOR">AUTHOR</a> |
56 | </li> |
61 | </li> |
57 | </ul><hr /> |
62 | </ul><hr /> |
58 | <!-- INDEX END --> |
63 | <!-- INDEX END --> |
59 | |
64 | |
60 | <h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> |
65 | <h1 id="NAME">NAME</h1> |
61 | <div id="NAME_CONTENT"> |
66 | <div id="NAME_CONTENT"> |
62 | <p>libev - a high performance full-featured event loop written in C</p> |
67 | <p>libev - a high performance full-featured event loop written in C</p> |
63 | |
68 | |
64 | </div> |
69 | </div> |
65 | <h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
70 | <h1 id="SYNOPSIS">SYNOPSIS</h1> |
66 | <div id="SYNOPSIS_CONTENT"> |
71 | <div id="SYNOPSIS_CONTENT"> |
67 | <pre> #include <ev.h> |
72 | <pre> #include <ev.h> |
68 | |
73 | |
69 | </pre> |
74 | </pre> |
70 | |
75 | |
71 | </div> |
76 | </div> |
72 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
77 | <h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1> |
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78 | <div id="EXAMPLE_PROGRAM_CONTENT"> |
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79 | <pre> #include <ev.h> |
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80 | |
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81 | ev_io stdin_watcher; |
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82 | ev_timer timeout_watcher; |
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83 | |
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84 | /* called when data readable on stdin */ |
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85 | static void |
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86 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
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87 | { |
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88 | /* puts ("stdin ready"); */ |
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89 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
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90 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
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91 | } |
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92 | |
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93 | static void |
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94 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
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95 | { |
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96 | /* puts ("timeout"); */ |
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97 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
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98 | } |
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99 | |
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100 | int |
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101 | main (void) |
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102 | { |
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103 | struct ev_loop *loop = ev_default_loop (0); |
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104 | |
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105 | /* initialise an io watcher, then start it */ |
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106 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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107 | ev_io_start (loop, &stdin_watcher); |
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108 | |
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109 | /* simple non-repeating 5.5 second timeout */ |
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110 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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111 | ev_timer_start (loop, &timeout_watcher); |
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112 | |
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113 | /* loop till timeout or data ready */ |
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114 | ev_loop (loop, 0); |
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115 | |
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116 | return 0; |
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117 | } |
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118 | |
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119 | </pre> |
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120 | |
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121 | </div> |
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122 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
73 | <div id="DESCRIPTION_CONTENT"> |
123 | <div id="DESCRIPTION_CONTENT"> |
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124 | <p>The newest version of this document is also available as a html-formatted |
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125 | web page you might find easier to navigate when reading it for the first |
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126 | time: <a href="http://cvs.schmorp.de/libev/ev.html">http://cvs.schmorp.de/libev/ev.html</a>.</p> |
74 | <p>Libev is an event loop: you register interest in certain events (such as a |
127 | <p>Libev is an event loop: you register interest in certain events (such as a |
75 | file descriptor being readable or a timeout occuring), and it will manage |
128 | file descriptor being readable or a timeout occuring), and it will manage |
76 | these event sources and provide your program with events.</p> |
129 | these event sources and provide your program with events.</p> |
77 | <p>To do this, it must take more or less complete control over your process |
130 | <p>To do this, it must take more or less complete control over your process |
78 | (or thread) by executing the <i>event loop</i> handler, and will then |
131 | (or thread) by executing the <i>event loop</i> handler, and will then |
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81 | watchers</i>, which are relatively small C structures you initialise with the |
134 | watchers</i>, which are relatively small C structures you initialise with the |
82 | details of the event, and then hand it over to libev by <i>starting</i> the |
135 | details of the event, and then hand it over to libev by <i>starting</i> the |
83 | watcher.</p> |
136 | watcher.</p> |
84 | |
137 | |
85 | </div> |
138 | </div> |
86 | <h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
139 | <h1 id="FEATURES">FEATURES</h1> |
87 | <div id="FEATURES_CONTENT"> |
140 | <div id="FEATURES_CONTENT"> |
88 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
141 | <p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the |
89 | kqueue mechanisms for file descriptor events, relative timers, absolute |
142 | BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms |
90 | timers with customised rescheduling, signal events, process status change |
143 | for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface |
91 | events (related to SIGCHLD), and event watchers dealing with the event |
144 | (for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers |
92 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
145 | with customised rescheduling (<code>ev_periodic</code>), synchronous signals |
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146 | (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event |
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147 | watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
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148 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
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149 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
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150 | (<code>ev_fork</code>).</p> |
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151 | <p>It also is quite fast (see this |
93 | fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing |
152 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
94 | it to libevent for example).</p> |
153 | for example).</p> |
95 | |
154 | |
96 | </div> |
155 | </div> |
97 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
156 | <h1 id="CONVENTIONS">CONVENTIONS</h1> |
98 | <div id="CONVENTIONS_CONTENT"> |
157 | <div id="CONVENTIONS_CONTENT"> |
99 | <p>Libev is very configurable. In this manual the default configuration |
158 | <p>Libev is very configurable. In this manual the default configuration will |
100 | will be described, which supports multiple event loops. For more info |
159 | be described, which supports multiple event loops. For more info about |
101 | about various configuration options please have a look at the file |
160 | various configuration options please have a look at <strong>EMBED</strong> section in |
102 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
161 | this manual. If libev was configured without support for multiple event |
103 | support for multiple event loops, then all functions taking an initial |
162 | loops, then all functions taking an initial argument of name <code>loop</code> |
104 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
163 | (which is always of type <code>struct ev_loop *</code>) will not have this argument.</p> |
105 | will not have this argument.</p> |
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106 | |
164 | |
107 | </div> |
165 | </div> |
108 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
166 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1> |
109 | <div id="TIME_REPRESENTATION_CONTENT"> |
167 | <div id="TIME_REPRESENTATION_CONTENT"> |
110 | <p>Libev represents time as a single floating point number, representing the |
168 | <p>Libev represents time as a single floating point number, representing the |
111 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
169 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
112 | the beginning of 1970, details are complicated, don't ask). This type is |
170 | the beginning of 1970, details are complicated, don't ask). This type is |
113 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
171 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
114 | to the <code>double</code> type in C, and when you need to do any calculations on |
172 | to the <code>double</code> type in C, and when you need to do any calculations on |
115 | it, you should treat it as such.</p> |
173 | it, you should treat it as such.</p> |
116 | |
174 | |
117 | |
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118 | |
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119 | |
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120 | |
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121 | </div> |
175 | </div> |
122 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
176 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1> |
123 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
177 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
124 | <p>These functions can be called anytime, even before initialising the |
178 | <p>These functions can be called anytime, even before initialising the |
125 | library in any way.</p> |
179 | library in any way.</p> |
126 | <dl> |
180 | <dl> |
127 | <dt>ev_tstamp ev_time ()</dt> |
181 | <dt>ev_tstamp ev_time ()</dt> |
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140 | version of the library your program was compiled against.</p> |
194 | version of the library your program was compiled against.</p> |
141 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
195 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
142 | as this indicates an incompatible change. Minor versions are usually |
196 | as this indicates an incompatible change. Minor versions are usually |
143 | compatible to older versions, so a larger minor version alone is usually |
197 | compatible to older versions, so a larger minor version alone is usually |
144 | not a problem.</p> |
198 | not a problem.</p> |
145 | <p>Example: make sure we haven't accidentally been linked against the wrong |
199 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
146 | version:</p> |
200 | version.</p> |
147 | <pre> assert (("libev version mismatch", |
201 | <pre> assert (("libev version mismatch", |
148 | ev_version_major () == EV_VERSION_MAJOR |
202 | ev_version_major () == EV_VERSION_MAJOR |
149 | && ev_version_minor () >= EV_VERSION_MINOR)); |
203 | && ev_version_minor () >= EV_VERSION_MINOR)); |
150 | |
204 | |
151 | </pre> |
205 | </pre> |
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181 | recommended ones.</p> |
235 | recommended ones.</p> |
182 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
236 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
183 | </dd> |
237 | </dd> |
184 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
238 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
185 | <dd> |
239 | <dd> |
186 | <p>Sets the allocation function to use (the prototype is similar to the |
240 | <p>Sets the allocation function to use (the prototype is similar - the |
187 | realloc C function, the semantics are identical). It is used to allocate |
241 | semantics is identical - to the realloc C function). It is used to |
188 | and free memory (no surprises here). If it returns zero when memory |
242 | allocate and free memory (no surprises here). If it returns zero when |
189 | needs to be allocated, the library might abort or take some potentially |
243 | memory needs to be allocated, the library might abort or take some |
190 | destructive action. The default is your system realloc function.</p> |
244 | potentially destructive action. The default is your system realloc |
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245 | function.</p> |
191 | <p>You could override this function in high-availability programs to, say, |
246 | <p>You could override this function in high-availability programs to, say, |
192 | free some memory if it cannot allocate memory, to use a special allocator, |
247 | free some memory if it cannot allocate memory, to use a special allocator, |
193 | or even to sleep a while and retry until some memory is available.</p> |
248 | or even to sleep a while and retry until some memory is available.</p> |
194 | <p>Example: replace the libev allocator with one that waits a bit and then |
249 | <p>Example: Replace the libev allocator with one that waits a bit and then |
195 | retries: better than mine).</p> |
250 | retries).</p> |
196 | <pre> static void * |
251 | <pre> static void * |
197 | persistent_realloc (void *ptr, long size) |
252 | persistent_realloc (void *ptr, size_t size) |
198 | { |
253 | { |
199 | for (;;) |
254 | for (;;) |
200 | { |
255 | { |
201 | void *newptr = realloc (ptr, size); |
256 | void *newptr = realloc (ptr, size); |
202 | |
257 | |
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219 | indicating the system call or subsystem causing the problem. If this |
274 | indicating the system call or subsystem causing the problem. If this |
220 | callback is set, then libev will expect it to remedy the sitution, no |
275 | callback is set, then libev will expect it to remedy the sitution, no |
221 | matter what, when it returns. That is, libev will generally retry the |
276 | matter what, when it returns. That is, libev will generally retry the |
222 | requested operation, or, if the condition doesn't go away, do bad stuff |
277 | requested operation, or, if the condition doesn't go away, do bad stuff |
223 | (such as abort).</p> |
278 | (such as abort).</p> |
224 | <p>Example: do the same thing as libev does internally:</p> |
279 | <p>Example: This is basically the same thing that libev does internally, too.</p> |
225 | <pre> static void |
280 | <pre> static void |
226 | fatal_error (const char *msg) |
281 | fatal_error (const char *msg) |
227 | { |
282 | { |
228 | perror (msg); |
283 | perror (msg); |
229 | abort (); |
284 | abort (); |
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235 | </pre> |
290 | </pre> |
236 | </dd> |
291 | </dd> |
237 | </dl> |
292 | </dl> |
238 | |
293 | |
239 | </div> |
294 | </div> |
240 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
295 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1> |
241 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
296 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
242 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
297 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
243 | types of such loops, the <i>default</i> loop, which supports signals and child |
298 | types of such loops, the <i>default</i> loop, which supports signals and child |
244 | events, and dynamically created loops which do not.</p> |
299 | events, and dynamically created loops which do not.</p> |
245 | <p>If you use threads, a common model is to run the default event loop |
300 | <p>If you use threads, a common model is to run the default event loop |
… | |
… | |
274 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
329 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
275 | override the flags completely if it is found in the environment. This is |
330 | override the flags completely if it is found in the environment. This is |
276 | useful to try out specific backends to test their performance, or to work |
331 | useful to try out specific backends to test their performance, or to work |
277 | around bugs.</p> |
332 | around bugs.</p> |
278 | </dd> |
333 | </dd> |
|
|
334 | <dt><code>EVFLAG_FORKCHECK</code></dt> |
|
|
335 | <dd> |
|
|
336 | <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after |
|
|
337 | a fork, you can also make libev check for a fork in each iteration by |
|
|
338 | enabling this flag.</p> |
|
|
339 | <p>This works by calling <code>getpid ()</code> on every iteration of the loop, |
|
|
340 | and thus this might slow down your event loop if you do a lot of loop |
|
|
341 | iterations and little real work, but is usually not noticeable (on my |
|
|
342 | Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence |
|
|
343 | without a syscall and thus <i>very</i> fast, but my Linux system also has |
|
|
344 | <code>pthread_atfork</code> which is even faster).</p> |
|
|
345 | <p>The big advantage of this flag is that you can forget about fork (and |
|
|
346 | forget about forgetting to tell libev about forking) when you use this |
|
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347 | flag.</p> |
|
|
348 | <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code> |
|
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349 | environment variable.</p> |
|
|
350 | </dd> |
279 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
351 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
280 | <dd> |
352 | <dd> |
281 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
353 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
282 | libev tries to roll its own fd_set with no limits on the number of fds, |
354 | libev tries to roll its own fd_set with no limits on the number of fds, |
283 | but if that fails, expect a fairly low limit on the number of fds when |
355 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
365 | <dd> |
437 | <dd> |
366 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
438 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
367 | always distinct from the default loop. Unlike the default loop, it cannot |
439 | always distinct from the default loop. Unlike the default loop, it cannot |
368 | handle signal and child watchers, and attempts to do so will be greeted by |
440 | handle signal and child watchers, and attempts to do so will be greeted by |
369 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
441 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
370 | <p>Example: try to create a event loop that uses epoll and nothing else.</p> |
442 | <p>Example: Try to create a event loop that uses epoll and nothing else.</p> |
371 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
443 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
372 | if (!epoller) |
444 | if (!epoller) |
373 | fatal ("no epoll found here, maybe it hides under your chair"); |
445 | fatal ("no epoll found here, maybe it hides under your chair"); |
374 | |
446 | |
375 | </pre> |
447 | </pre> |
… | |
… | |
411 | <dt>ev_loop_fork (loop)</dt> |
483 | <dt>ev_loop_fork (loop)</dt> |
412 | <dd> |
484 | <dd> |
413 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
485 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
414 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
486 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
415 | after fork, and how you do this is entirely your own problem.</p> |
487 | after fork, and how you do this is entirely your own problem.</p> |
|
|
488 | </dd> |
|
|
489 | <dt>unsigned int ev_loop_count (loop)</dt> |
|
|
490 | <dd> |
|
|
491 | <p>Returns the count of loop iterations for the loop, which is identical to |
|
|
492 | the number of times libev did poll for new events. It starts at <code>0</code> and |
|
|
493 | happily wraps around with enough iterations.</p> |
|
|
494 | <p>This value can sometimes be useful as a generation counter of sorts (it |
|
|
495 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
496 | <code>ev_prepare</code> and <code>ev_check</code> calls.</p> |
416 | </dd> |
497 | </dd> |
417 | <dt>unsigned int ev_backend (loop)</dt> |
498 | <dt>unsigned int ev_backend (loop)</dt> |
418 | <dd> |
499 | <dd> |
419 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
500 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
420 | use.</p> |
501 | use.</p> |
… | |
… | |
468 | be handled here by queueing them when their watcher gets executed. |
549 | be handled here by queueing them when their watcher gets executed. |
469 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
550 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
470 | were used, return, otherwise continue with step *. |
551 | were used, return, otherwise continue with step *. |
471 | |
552 | |
472 | </pre> |
553 | </pre> |
473 | <p>Example: queue some jobs and then loop until no events are outsanding |
554 | <p>Example: Queue some jobs and then loop until no events are outsanding |
474 | anymore.</p> |
555 | anymore.</p> |
475 | <pre> ... queue jobs here, make sure they register event watchers as long |
556 | <pre> ... queue jobs here, make sure they register event watchers as long |
476 | ... as they still have work to do (even an idle watcher will do..) |
557 | ... as they still have work to do (even an idle watcher will do..) |
477 | ev_loop (my_loop, 0); |
558 | ev_loop (my_loop, 0); |
478 | ... jobs done. yeah! |
559 | ... jobs done. yeah! |
… | |
… | |
497 | example, libev itself uses this for its internal signal pipe: It is not |
578 | example, libev itself uses this for its internal signal pipe: It is not |
498 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
579 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
499 | no event watchers registered by it are active. It is also an excellent |
580 | no event watchers registered by it are active. It is also an excellent |
500 | way to do this for generic recurring timers or from within third-party |
581 | way to do this for generic recurring timers or from within third-party |
501 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
582 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
502 | <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> |
583 | <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code> |
503 | running when nothing else is active.</p> |
584 | running when nothing else is active.</p> |
504 | <pre> struct dv_signal exitsig; |
585 | <pre> struct ev_signal exitsig; |
505 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
586 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
506 | ev_signal_start (myloop, &exitsig); |
587 | ev_signal_start (loop, &exitsig); |
507 | evf_unref (myloop); |
588 | evf_unref (loop); |
508 | |
589 | |
509 | </pre> |
590 | </pre> |
510 | <p>Example: for some weird reason, unregister the above signal handler again.</p> |
591 | <p>Example: For some weird reason, unregister the above signal handler again.</p> |
511 | <pre> ev_ref (myloop); |
592 | <pre> ev_ref (loop); |
512 | ev_signal_stop (myloop, &exitsig); |
593 | ev_signal_stop (loop, &exitsig); |
513 | |
594 | |
514 | </pre> |
595 | </pre> |
515 | </dd> |
596 | </dd> |
516 | </dl> |
597 | </dl> |
517 | |
598 | |
|
|
599 | |
|
|
600 | |
|
|
601 | |
|
|
602 | |
518 | </div> |
603 | </div> |
519 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
604 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1> |
520 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
605 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
521 | <p>A watcher is a structure that you create and register to record your |
606 | <p>A watcher is a structure that you create and register to record your |
522 | interest in some event. For instance, if you want to wait for STDIN to |
607 | interest in some event. For instance, if you want to wait for STDIN to |
523 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
608 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
524 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
609 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
581 | </dd> |
666 | </dd> |
582 | <dt><code>EV_CHILD</code></dt> |
667 | <dt><code>EV_CHILD</code></dt> |
583 | <dd> |
668 | <dd> |
584 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
669 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
585 | </dd> |
670 | </dd> |
|
|
671 | <dt><code>EV_STAT</code></dt> |
|
|
672 | <dd> |
|
|
673 | <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p> |
|
|
674 | </dd> |
586 | <dt><code>EV_IDLE</code></dt> |
675 | <dt><code>EV_IDLE</code></dt> |
587 | <dd> |
676 | <dd> |
588 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
677 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
589 | </dd> |
678 | </dd> |
590 | <dt><code>EV_PREPARE</code></dt> |
679 | <dt><code>EV_PREPARE</code></dt> |
… | |
… | |
595 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
684 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
596 | received events. Callbacks of both watcher types can start and stop as |
685 | received events. Callbacks of both watcher types can start and stop as |
597 | many watchers as they want, and all of them will be taken into account |
686 | many watchers as they want, and all of them will be taken into account |
598 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
687 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
599 | <code>ev_loop</code> from blocking).</p> |
688 | <code>ev_loop</code> from blocking).</p> |
|
|
689 | </dd> |
|
|
690 | <dt><code>EV_EMBED</code></dt> |
|
|
691 | <dd> |
|
|
692 | <p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p> |
|
|
693 | </dd> |
|
|
694 | <dt><code>EV_FORK</code></dt> |
|
|
695 | <dd> |
|
|
696 | <p>The event loop has been resumed in the child process after fork (see |
|
|
697 | <code>ev_fork</code>).</p> |
600 | </dd> |
698 | </dd> |
601 | <dt><code>EV_ERROR</code></dt> |
699 | <dt><code>EV_ERROR</code></dt> |
602 | <dd> |
700 | <dd> |
603 | <p>An unspecified error has occured, the watcher has been stopped. This might |
701 | <p>An unspecified error has occured, the watcher has been stopped. This might |
604 | happen because the watcher could not be properly started because libev |
702 | happen because the watcher could not be properly started because libev |
… | |
… | |
612 | programs, though, so beware.</p> |
710 | programs, though, so beware.</p> |
613 | </dd> |
711 | </dd> |
614 | </dl> |
712 | </dl> |
615 | |
713 | |
616 | </div> |
714 | </div> |
617 | <h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2> |
715 | <h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2> |
618 | <div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2"> |
716 | <div id="GENERIC_WATCHER_FUNCTIONS_CONTENT"> |
619 | <p>In the following description, <code>TYPE</code> stands for the watcher type, |
717 | <p>In the following description, <code>TYPE</code> stands for the watcher type, |
620 | e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> |
718 | e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> |
621 | <dl> |
719 | <dl> |
622 | <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> |
720 | <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> |
623 | <dd> |
721 | <dd> |
… | |
… | |
627 | the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the |
725 | the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the |
628 | type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro |
726 | type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro |
629 | which rolls both calls into one.</p> |
727 | which rolls both calls into one.</p> |
630 | <p>You can reinitialise a watcher at any time as long as it has been stopped |
728 | <p>You can reinitialise a watcher at any time as long as it has been stopped |
631 | (or never started) and there are no pending events outstanding.</p> |
729 | (or never started) and there are no pending events outstanding.</p> |
632 | <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, |
730 | <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, |
633 | int revents)</code>.</p> |
731 | int revents)</code>.</p> |
634 | </dd> |
732 | </dd> |
635 | <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> |
733 | <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> |
636 | <dd> |
734 | <dd> |
637 | <p>This macro initialises the type-specific parts of a watcher. You need to |
735 | <p>This macro initialises the type-specific parts of a watcher. You need to |
… | |
… | |
674 | events but its callback has not yet been invoked). As long as a watcher |
772 | events but its callback has not yet been invoked). As long as a watcher |
675 | is pending (but not active) you must not call an init function on it (but |
773 | is pending (but not active) you must not call an init function on it (but |
676 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
774 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
677 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
775 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
678 | </dd> |
776 | </dd> |
679 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
777 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
680 | <dd> |
778 | <dd> |
681 | <p>Returns the callback currently set on the watcher.</p> |
779 | <p>Returns the callback currently set on the watcher.</p> |
682 | </dd> |
780 | </dd> |
683 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
781 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
684 | <dd> |
782 | <dd> |
685 | <p>Change the callback. You can change the callback at virtually any time |
783 | <p>Change the callback. You can change the callback at virtually any time |
686 | (modulo threads).</p> |
784 | (modulo threads).</p> |
|
|
785 | </dd> |
|
|
786 | <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt> |
|
|
787 | <dt>int ev_priority (ev_TYPE *watcher)</dt> |
|
|
788 | <dd> |
|
|
789 | <p>Set and query the priority of the watcher. The priority is a small |
|
|
790 | integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code> |
|
|
791 | (default: <code>-2</code>). Pending watchers with higher priority will be invoked |
|
|
792 | before watchers with lower priority, but priority will not keep watchers |
|
|
793 | from being executed (except for <code>ev_idle</code> watchers).</p> |
|
|
794 | <p>This means that priorities are <i>only</i> used for ordering callback |
|
|
795 | invocation after new events have been received. This is useful, for |
|
|
796 | example, to reduce latency after idling, or more often, to bind two |
|
|
797 | watchers on the same event and make sure one is called first.</p> |
|
|
798 | <p>If you need to suppress invocation when higher priority events are pending |
|
|
799 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
|
|
800 | <p>The default priority used by watchers when no priority has been set is |
|
|
801 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
|
|
802 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
|
|
803 | fine, as long as you do not mind that the priority value you query might |
|
|
804 | or might not have been adjusted to be within valid range.</p> |
687 | </dd> |
805 | </dd> |
688 | </dl> |
806 | </dl> |
689 | |
807 | |
690 | |
808 | |
691 | |
809 | |
… | |
… | |
716 | struct my_io *w = (struct my_io *)w_; |
834 | struct my_io *w = (struct my_io *)w_; |
717 | ... |
835 | ... |
718 | } |
836 | } |
719 | |
837 | |
720 | </pre> |
838 | </pre> |
721 | <p>More interesting and less C-conformant ways of catsing your callback type |
839 | <p>More interesting and less C-conformant ways of casting your callback type |
722 | have been omitted....</p> |
840 | instead have been omitted.</p> |
|
|
841 | <p>Another common scenario is having some data structure with multiple |
|
|
842 | watchers:</p> |
|
|
843 | <pre> struct my_biggy |
|
|
844 | { |
|
|
845 | int some_data; |
|
|
846 | ev_timer t1; |
|
|
847 | ev_timer t2; |
|
|
848 | } |
723 | |
849 | |
|
|
850 | </pre> |
|
|
851 | <p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated, |
|
|
852 | you need to use <code>offsetof</code>:</p> |
|
|
853 | <pre> #include <stddef.h> |
724 | |
854 | |
|
|
855 | static void |
|
|
856 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
857 | { |
|
|
858 | struct my_biggy big = (struct my_biggy * |
|
|
859 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
860 | } |
725 | |
861 | |
|
|
862 | static void |
|
|
863 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
864 | { |
|
|
865 | struct my_biggy big = (struct my_biggy * |
|
|
866 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
867 | } |
726 | |
868 | |
727 | |
869 | |
|
|
870 | |
|
|
871 | |
|
|
872 | </pre> |
|
|
873 | |
728 | </div> |
874 | </div> |
729 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
875 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
730 | <div id="WATCHER_TYPES_CONTENT"> |
876 | <div id="WATCHER_TYPES_CONTENT"> |
731 | <p>This section describes each watcher in detail, but will not repeat |
877 | <p>This section describes each watcher in detail, but will not repeat |
732 | information given in the last section.</p> |
878 | information given in the last section. Any initialisation/set macros, |
|
|
879 | functions and members specific to the watcher type are explained.</p> |
|
|
880 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
|
|
881 | while the watcher is active, you can look at the member and expect some |
|
|
882 | sensible content, but you must not modify it (you can modify it while the |
|
|
883 | watcher is stopped to your hearts content), or <i>[read-write]</i>, which |
|
|
884 | means you can expect it to have some sensible content while the watcher |
|
|
885 | is active, but you can also modify it. Modifying it may not do something |
|
|
886 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
887 | not crash or malfunction in any way.</p> |
733 | |
888 | |
734 | |
889 | |
735 | |
890 | |
736 | |
891 | |
737 | |
892 | |
738 | </div> |
893 | </div> |
739 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
894 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2> |
740 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
895 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
741 | <p>I/O watchers check whether a file descriptor is readable or writable |
896 | <p>I/O watchers check whether a file descriptor is readable or writable |
742 | in each iteration of the event loop (This behaviour is called |
897 | in each iteration of the event loop, or, more precisely, when reading |
743 | level-triggering because you keep receiving events as long as the |
898 | would not block the process and writing would at least be able to write |
744 | condition persists. Remember you can stop the watcher if you don't want to |
899 | some data. This behaviour is called level-triggering because you keep |
745 | act on the event and neither want to receive future events).</p> |
900 | receiving events as long as the condition persists. Remember you can stop |
|
|
901 | the watcher if you don't want to act on the event and neither want to |
|
|
902 | receive future events.</p> |
746 | <p>In general you can register as many read and/or write event watchers per |
903 | <p>In general you can register as many read and/or write event watchers per |
747 | fd as you want (as long as you don't confuse yourself). Setting all file |
904 | fd as you want (as long as you don't confuse yourself). Setting all file |
748 | descriptors to non-blocking mode is also usually a good idea (but not |
905 | descriptors to non-blocking mode is also usually a good idea (but not |
749 | required if you know what you are doing).</p> |
906 | required if you know what you are doing).</p> |
750 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
907 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
751 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
908 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
752 | descriptors correctly if you register interest in two or more fds pointing |
909 | descriptors correctly if you register interest in two or more fds pointing |
753 | to the same underlying file/socket etc. description (that is, they share |
910 | to the same underlying file/socket/etc. description (that is, they share |
754 | the same underlying "file open").</p> |
911 | the same underlying "file open").</p> |
755 | <p>If you must do this, then force the use of a known-to-be-good backend |
912 | <p>If you must do this, then force the use of a known-to-be-good backend |
756 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
913 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
757 | <code>EVBACKEND_POLL</code>).</p> |
914 | <code>EVBACKEND_POLL</code>).</p> |
|
|
915 | <p>Another thing you have to watch out for is that it is quite easy to |
|
|
916 | receive "spurious" readyness notifications, that is your callback might |
|
|
917 | be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block |
|
|
918 | because there is no data. Not only are some backends known to create a |
|
|
919 | lot of those (for example solaris ports), it is very easy to get into |
|
|
920 | this situation even with a relatively standard program structure. Thus |
|
|
921 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
|
|
922 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
|
|
923 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
|
|
924 | play around with an Xlib connection), then you have to seperately re-test |
|
|
925 | whether a file descriptor is really ready with a known-to-be good interface |
|
|
926 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
927 | its own, so its quite safe to use).</p> |
758 | <dl> |
928 | <dl> |
759 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
929 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
760 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
930 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
761 | <dd> |
931 | <dd> |
762 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
932 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
763 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
933 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
764 | EV_WRITE</code> to receive the given events.</p> |
934 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
765 | <p>Please note that most of the more scalable backend mechanisms (for example |
935 | </dd> |
766 | epoll and solaris ports) can result in spurious readyness notifications |
936 | <dt>int fd [read-only]</dt> |
767 | for file descriptors, so you practically need to use non-blocking I/O (and |
937 | <dd> |
768 | treat callback invocation as hint only), or retest separately with a safe |
938 | <p>The file descriptor being watched.</p> |
769 | interface before doing I/O (XLib can do this), or force the use of either |
939 | </dd> |
770 | <code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this |
940 | <dt>int events [read-only]</dt> |
771 | problem. Also note that it is quite easy to have your callback invoked |
941 | <dd> |
772 | when the readyness condition is no longer valid even when employing |
942 | <p>The events being watched.</p> |
773 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
774 | I/O unconditionally.</p> |
|
|
775 | </dd> |
943 | </dd> |
776 | </dl> |
944 | </dl> |
777 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
945 | <p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
778 | readable, but only once. Since it is likely line-buffered, you could |
946 | readable, but only once. Since it is likely line-buffered, you could |
779 | attempt to read a whole line in the callback:</p> |
947 | attempt to read a whole line in the callback.</p> |
780 | <pre> static void |
948 | <pre> static void |
781 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
949 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
782 | { |
950 | { |
783 | ev_io_stop (loop, w); |
951 | ev_io_stop (loop, w); |
784 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
952 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
… | |
… | |
795 | |
963 | |
796 | |
964 | |
797 | </pre> |
965 | </pre> |
798 | |
966 | |
799 | </div> |
967 | </div> |
800 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
968 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2> |
801 | <div id="code_ev_timer_code_relative_and_opti-2"> |
969 | <div id="code_ev_timer_code_relative_and_opti-2"> |
802 | <p>Timer watchers are simple relative timers that generate an event after a |
970 | <p>Timer watchers are simple relative timers that generate an event after a |
803 | given time, and optionally repeating in regular intervals after that.</p> |
971 | given time, and optionally repeating in regular intervals after that.</p> |
804 | <p>The timers are based on real time, that is, if you register an event that |
972 | <p>The timers are based on real time, that is, if you register an event that |
805 | times out after an hour and you reset your system clock to last years |
973 | times out after an hour and you reset your system clock to last years |
… | |
… | |
833 | </dd> |
1001 | </dd> |
834 | <dt>ev_timer_again (loop)</dt> |
1002 | <dt>ev_timer_again (loop)</dt> |
835 | <dd> |
1003 | <dd> |
836 | <p>This will act as if the timer timed out and restart it again if it is |
1004 | <p>This will act as if the timer timed out and restart it again if it is |
837 | repeating. The exact semantics are:</p> |
1005 | repeating. The exact semantics are:</p> |
|
|
1006 | <p>If the timer is pending, its pending status is cleared.</p> |
838 | <p>If the timer is started but nonrepeating, stop it.</p> |
1007 | <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p> |
839 | <p>If the timer is repeating, either start it if necessary (with the repeat |
1008 | <p>If the timer is repeating, either start it if necessary (with the |
840 | value), or reset the running timer to the repeat value.</p> |
1009 | <code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p> |
841 | <p>This sounds a bit complicated, but here is a useful and typical |
1010 | <p>This sounds a bit complicated, but here is a useful and typical |
842 | example: Imagine you have a tcp connection and you want a so-called idle |
1011 | example: Imagine you have a tcp connection and you want a so-called idle |
843 | timeout, that is, you want to be called when there have been, say, 60 |
1012 | timeout, that is, you want to be called when there have been, say, 60 |
844 | seconds of inactivity on the socket. The easiest way to do this is to |
1013 | seconds of inactivity on the socket. The easiest way to do this is to |
845 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
1014 | configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call |
846 | time you successfully read or write some data. If you go into an idle |
1015 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
847 | state where you do not expect data to travel on the socket, you can stop |
1016 | you go into an idle state where you do not expect data to travel on the |
|
|
1017 | socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will |
848 | the timer, and again will automatically restart it if need be.</p> |
1018 | automatically restart it if need be.</p> |
|
|
1019 | <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code> |
|
|
1020 | altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p> |
|
|
1021 | <pre> ev_timer_init (timer, callback, 0., 5.); |
|
|
1022 | ev_timer_again (loop, timer); |
|
|
1023 | ... |
|
|
1024 | timer->again = 17.; |
|
|
1025 | ev_timer_again (loop, timer); |
|
|
1026 | ... |
|
|
1027 | timer->again = 10.; |
|
|
1028 | ev_timer_again (loop, timer); |
|
|
1029 | |
|
|
1030 | </pre> |
|
|
1031 | <p>This is more slightly efficient then stopping/starting the timer each time |
|
|
1032 | you want to modify its timeout value.</p> |
|
|
1033 | </dd> |
|
|
1034 | <dt>ev_tstamp repeat [read-write]</dt> |
|
|
1035 | <dd> |
|
|
1036 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
|
|
1037 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
|
|
1038 | which is also when any modifications are taken into account.</p> |
849 | </dd> |
1039 | </dd> |
850 | </dl> |
1040 | </dl> |
851 | <p>Example: create a timer that fires after 60 seconds.</p> |
1041 | <p>Example: Create a timer that fires after 60 seconds.</p> |
852 | <pre> static void |
1042 | <pre> static void |
853 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1043 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
854 | { |
1044 | { |
855 | .. one minute over, w is actually stopped right here |
1045 | .. one minute over, w is actually stopped right here |
856 | } |
1046 | } |
… | |
… | |
858 | struct ev_timer mytimer; |
1048 | struct ev_timer mytimer; |
859 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1049 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
860 | ev_timer_start (loop, &mytimer); |
1050 | ev_timer_start (loop, &mytimer); |
861 | |
1051 | |
862 | </pre> |
1052 | </pre> |
863 | <p>Example: create a timeout timer that times out after 10 seconds of |
1053 | <p>Example: Create a timeout timer that times out after 10 seconds of |
864 | inactivity.</p> |
1054 | inactivity.</p> |
865 | <pre> static void |
1055 | <pre> static void |
866 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1056 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
867 | { |
1057 | { |
868 | .. ten seconds without any activity |
1058 | .. ten seconds without any activity |
… | |
… | |
881 | |
1071 | |
882 | |
1072 | |
883 | </pre> |
1073 | </pre> |
884 | |
1074 | |
885 | </div> |
1075 | </div> |
886 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
1076 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2> |
887 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
1077 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
888 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
1078 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
889 | (and unfortunately a bit complex).</p> |
1079 | (and unfortunately a bit complex).</p> |
890 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
1080 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
891 | but on wallclock time (absolute time). You can tell a periodic watcher |
1081 | but on wallclock time (absolute time). You can tell a periodic watcher |
… | |
… | |
971 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1161 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
972 | when you changed some parameters or the reschedule callback would return |
1162 | when you changed some parameters or the reschedule callback would return |
973 | a different time than the last time it was called (e.g. in a crond like |
1163 | a different time than the last time it was called (e.g. in a crond like |
974 | program when the crontabs have changed).</p> |
1164 | program when the crontabs have changed).</p> |
975 | </dd> |
1165 | </dd> |
|
|
1166 | <dt>ev_tstamp interval [read-write]</dt> |
|
|
1167 | <dd> |
|
|
1168 | <p>The current interval value. Can be modified any time, but changes only |
|
|
1169 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
|
|
1170 | called.</p> |
|
|
1171 | </dd> |
|
|
1172 | <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt> |
|
|
1173 | <dd> |
|
|
1174 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
|
|
1175 | switched off. Can be changed any time, but changes only take effect when |
|
|
1176 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
|
|
1177 | </dd> |
976 | </dl> |
1178 | </dl> |
977 | <p>Example: call a callback every hour, or, more precisely, whenever the |
1179 | <p>Example: Call a callback every hour, or, more precisely, whenever the |
978 | system clock is divisible by 3600. The callback invocation times have |
1180 | system clock is divisible by 3600. The callback invocation times have |
979 | potentially a lot of jittering, but good long-term stability.</p> |
1181 | potentially a lot of jittering, but good long-term stability.</p> |
980 | <pre> static void |
1182 | <pre> static void |
981 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1183 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
982 | { |
1184 | { |
… | |
… | |
986 | struct ev_periodic hourly_tick; |
1188 | struct ev_periodic hourly_tick; |
987 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1189 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
988 | ev_periodic_start (loop, &hourly_tick); |
1190 | ev_periodic_start (loop, &hourly_tick); |
989 | |
1191 | |
990 | </pre> |
1192 | </pre> |
991 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
1193 | <p>Example: The same as above, but use a reschedule callback to do it:</p> |
992 | <pre> #include <math.h> |
1194 | <pre> #include <math.h> |
993 | |
1195 | |
994 | static ev_tstamp |
1196 | static ev_tstamp |
995 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1197 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
996 | { |
1198 | { |
… | |
… | |
998 | } |
1200 | } |
999 | |
1201 | |
1000 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1202 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1001 | |
1203 | |
1002 | </pre> |
1204 | </pre> |
1003 | <p>Example: call a callback every hour, starting now:</p> |
1205 | <p>Example: Call a callback every hour, starting now:</p> |
1004 | <pre> struct ev_periodic hourly_tick; |
1206 | <pre> struct ev_periodic hourly_tick; |
1005 | ev_periodic_init (&hourly_tick, clock_cb, |
1207 | ev_periodic_init (&hourly_tick, clock_cb, |
1006 | fmod (ev_now (loop), 3600.), 3600., 0); |
1208 | fmod (ev_now (loop), 3600.), 3600., 0); |
1007 | ev_periodic_start (loop, &hourly_tick); |
1209 | ev_periodic_start (loop, &hourly_tick); |
1008 | |
1210 | |
… | |
… | |
1010 | |
1212 | |
1011 | |
1213 | |
1012 | </pre> |
1214 | </pre> |
1013 | |
1215 | |
1014 | </div> |
1216 | </div> |
1015 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
1217 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2> |
1016 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
1218 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
1017 | <p>Signal watchers will trigger an event when the process receives a specific |
1219 | <p>Signal watchers will trigger an event when the process receives a specific |
1018 | signal one or more times. Even though signals are very asynchronous, libev |
1220 | signal one or more times. Even though signals are very asynchronous, libev |
1019 | will try it's best to deliver signals synchronously, i.e. as part of the |
1221 | will try it's best to deliver signals synchronously, i.e. as part of the |
1020 | normal event processing, like any other event.</p> |
1222 | normal event processing, like any other event.</p> |
… | |
… | |
1029 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1231 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1030 | <dd> |
1232 | <dd> |
1031 | <p>Configures the watcher to trigger on the given signal number (usually one |
1233 | <p>Configures the watcher to trigger on the given signal number (usually one |
1032 | of the <code>SIGxxx</code> constants).</p> |
1234 | of the <code>SIGxxx</code> constants).</p> |
1033 | </dd> |
1235 | </dd> |
|
|
1236 | <dt>int signum [read-only]</dt> |
|
|
1237 | <dd> |
|
|
1238 | <p>The signal the watcher watches out for.</p> |
|
|
1239 | </dd> |
1034 | </dl> |
1240 | </dl> |
1035 | |
1241 | |
1036 | |
1242 | |
1037 | |
1243 | |
1038 | |
1244 | |
1039 | |
1245 | |
1040 | </div> |
1246 | </div> |
1041 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
1247 | <h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> |
1042 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
1248 | <div id="code_ev_child_code_watch_out_for_pro-2"> |
1043 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1249 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1044 | some child status changes (most typically when a child of yours dies).</p> |
1250 | some child status changes (most typically when a child of yours dies).</p> |
1045 | <dl> |
1251 | <dl> |
1046 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1252 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1047 | <dt>ev_child_set (ev_child *, int pid)</dt> |
1253 | <dt>ev_child_set (ev_child *, int pid)</dt> |
… | |
… | |
1051 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1257 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1052 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1258 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1053 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1259 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1054 | process causing the status change.</p> |
1260 | process causing the status change.</p> |
1055 | </dd> |
1261 | </dd> |
|
|
1262 | <dt>int pid [read-only]</dt> |
|
|
1263 | <dd> |
|
|
1264 | <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p> |
|
|
1265 | </dd> |
|
|
1266 | <dt>int rpid [read-write]</dt> |
|
|
1267 | <dd> |
|
|
1268 | <p>The process id that detected a status change.</p> |
|
|
1269 | </dd> |
|
|
1270 | <dt>int rstatus [read-write]</dt> |
|
|
1271 | <dd> |
|
|
1272 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
|
|
1273 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
|
|
1274 | </dd> |
1056 | </dl> |
1275 | </dl> |
1057 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
1276 | <p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p> |
1058 | <pre> static void |
1277 | <pre> static void |
1059 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1278 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1060 | { |
1279 | { |
1061 | ev_unloop (loop, EVUNLOOP_ALL); |
1280 | ev_unloop (loop, EVUNLOOP_ALL); |
1062 | } |
1281 | } |
… | |
… | |
1069 | |
1288 | |
1070 | |
1289 | |
1071 | </pre> |
1290 | </pre> |
1072 | |
1291 | |
1073 | </div> |
1292 | </div> |
|
|
1293 | <h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2> |
|
|
1294 | <div id="code_ev_stat_code_did_the_file_attri-2"> |
|
|
1295 | <p>This watches a filesystem path for attribute changes. That is, it calls |
|
|
1296 | <code>stat</code> regularly (or when the OS says it changed) and sees if it changed |
|
|
1297 | compared to the last time, invoking the callback if it did.</p> |
|
|
1298 | <p>The path does not need to exist: changing from "path exists" to "path does |
|
|
1299 | not exist" is a status change like any other. The condition "path does |
|
|
1300 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
|
|
1301 | otherwise always forced to be at least one) and all the other fields of |
|
|
1302 | the stat buffer having unspecified contents.</p> |
|
|
1303 | <p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is |
|
|
1304 | relative and your working directory changes, the behaviour is undefined.</p> |
|
|
1305 | <p>Since there is no standard to do this, the portable implementation simply |
|
|
1306 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
|
|
1307 | can specify a recommended polling interval for this case. If you specify |
|
|
1308 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
|
|
1309 | unspecified default</i> value will be used (which you can expect to be around |
|
|
1310 | five seconds, although this might change dynamically). Libev will also |
|
|
1311 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
|
|
1312 | usually overkill.</p> |
|
|
1313 | <p>This watcher type is not meant for massive numbers of stat watchers, |
|
|
1314 | as even with OS-supported change notifications, this can be |
|
|
1315 | resource-intensive.</p> |
|
|
1316 | <p>At the time of this writing, only the Linux inotify interface is |
|
|
1317 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1318 | reader). Inotify will be used to give hints only and should not change the |
|
|
1319 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
|
|
1320 | to fall back to regular polling again even with inotify, but changes are |
|
|
1321 | usually detected immediately, and if the file exists there will be no |
|
|
1322 | polling.</p> |
|
|
1323 | <dl> |
|
|
1324 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
|
|
1325 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
|
|
1326 | <dd> |
|
|
1327 | <p>Configures the watcher to wait for status changes of the given |
|
|
1328 | <code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to |
|
|
1329 | be detected and should normally be specified as <code>0</code> to let libev choose |
|
|
1330 | a suitable value. The memory pointed to by <code>path</code> must point to the same |
|
|
1331 | path for as long as the watcher is active.</p> |
|
|
1332 | <p>The callback will be receive <code>EV_STAT</code> when a change was detected, |
|
|
1333 | relative to the attributes at the time the watcher was started (or the |
|
|
1334 | last change was detected).</p> |
|
|
1335 | </dd> |
|
|
1336 | <dt>ev_stat_stat (ev_stat *)</dt> |
|
|
1337 | <dd> |
|
|
1338 | <p>Updates the stat buffer immediately with new values. If you change the |
|
|
1339 | watched path in your callback, you could call this fucntion to avoid |
|
|
1340 | detecting this change (while introducing a race condition). Can also be |
|
|
1341 | useful simply to find out the new values.</p> |
|
|
1342 | </dd> |
|
|
1343 | <dt>ev_statdata attr [read-only]</dt> |
|
|
1344 | <dd> |
|
|
1345 | <p>The most-recently detected attributes of the file. Although the type is of |
|
|
1346 | <code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types |
|
|
1347 | suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there |
|
|
1348 | was some error while <code>stat</code>ing the file.</p> |
|
|
1349 | </dd> |
|
|
1350 | <dt>ev_statdata prev [read-only]</dt> |
|
|
1351 | <dd> |
|
|
1352 | <p>The previous attributes of the file. The callback gets invoked whenever |
|
|
1353 | <code>prev</code> != <code>attr</code>.</p> |
|
|
1354 | </dd> |
|
|
1355 | <dt>ev_tstamp interval [read-only]</dt> |
|
|
1356 | <dd> |
|
|
1357 | <p>The specified interval.</p> |
|
|
1358 | </dd> |
|
|
1359 | <dt>const char *path [read-only]</dt> |
|
|
1360 | <dd> |
|
|
1361 | <p>The filesystem path that is being watched.</p> |
|
|
1362 | </dd> |
|
|
1363 | </dl> |
|
|
1364 | <p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p> |
|
|
1365 | <pre> static void |
|
|
1366 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1367 | { |
|
|
1368 | /* /etc/passwd changed in some way */ |
|
|
1369 | if (w->attr.st_nlink) |
|
|
1370 | { |
|
|
1371 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1372 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1373 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1374 | } |
|
|
1375 | else |
|
|
1376 | /* you shalt not abuse printf for puts */ |
|
|
1377 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1378 | "if this is windows, they already arrived\n"); |
|
|
1379 | } |
|
|
1380 | |
|
|
1381 | ... |
|
|
1382 | ev_stat passwd; |
|
|
1383 | |
|
|
1384 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1385 | ev_stat_start (loop, &passwd); |
|
|
1386 | |
|
|
1387 | |
|
|
1388 | |
|
|
1389 | |
|
|
1390 | </pre> |
|
|
1391 | |
|
|
1392 | </div> |
1074 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
1393 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1075 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1394 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1076 | <p>Idle watchers trigger events when there are no other events are pending |
1395 | <p>Idle watchers trigger events when no other events of the same or higher |
1077 | (prepare, check and other idle watchers do not count). That is, as long |
1396 | priority are pending (prepare, check and other idle watchers do not |
1078 | as your process is busy handling sockets or timeouts (or even signals, |
1397 | count).</p> |
1079 | imagine) it will not be triggered. But when your process is idle all idle |
1398 | <p>That is, as long as your process is busy handling sockets or timeouts |
1080 | watchers are being called again and again, once per event loop iteration - |
1399 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1400 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1401 | are pending), the idle watchers are being called once per event loop |
1081 | until stopped, that is, or your process receives more events and becomes |
1402 | iteration - until stopped, that is, or your process receives more events |
1082 | busy.</p> |
1403 | and becomes busy again with higher priority stuff.</p> |
1083 | <p>The most noteworthy effect is that as long as any idle watchers are |
1404 | <p>The most noteworthy effect is that as long as any idle watchers are |
1084 | active, the process will not block when waiting for new events.</p> |
1405 | active, the process will not block when waiting for new events.</p> |
1085 | <p>Apart from keeping your process non-blocking (which is a useful |
1406 | <p>Apart from keeping your process non-blocking (which is a useful |
1086 | effect on its own sometimes), idle watchers are a good place to do |
1407 | effect on its own sometimes), idle watchers are a good place to do |
1087 | "pseudo-background processing", or delay processing stuff to after the |
1408 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
1092 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1413 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1093 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1414 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1094 | believe me.</p> |
1415 | believe me.</p> |
1095 | </dd> |
1416 | </dd> |
1096 | </dl> |
1417 | </dl> |
1097 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
1418 | <p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the |
1098 | callback, free it. Alos, use no error checking, as usual.</p> |
1419 | callback, free it. Also, use no error checking, as usual.</p> |
1099 | <pre> static void |
1420 | <pre> static void |
1100 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1421 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1101 | { |
1422 | { |
1102 | free (w); |
1423 | free (w); |
1103 | // now do something you wanted to do when the program has |
1424 | // now do something you wanted to do when the program has |
… | |
… | |
1112 | |
1433 | |
1113 | |
1434 | |
1114 | </pre> |
1435 | </pre> |
1115 | |
1436 | |
1116 | </div> |
1437 | </div> |
1117 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
1438 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2> |
1118 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1439 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1119 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1440 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1120 | prepare watchers get invoked before the process blocks and check watchers |
1441 | prepare watchers get invoked before the process blocks and check watchers |
1121 | afterwards.</p> |
1442 | afterwards.</p> |
|
|
1443 | <p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter |
|
|
1444 | the current event loop from either <code>ev_prepare</code> or <code>ev_check</code> |
|
|
1445 | watchers. Other loops than the current one are fine, however. The |
|
|
1446 | rationale behind this is that you do not need to check for recursion in |
|
|
1447 | those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking, |
|
|
1448 | <code>ev_check</code> so if you have one watcher of each kind they will always be |
|
|
1449 | called in pairs bracketing the blocking call.</p> |
1122 | <p>Their main purpose is to integrate other event mechanisms into libev and |
1450 | <p>Their main purpose is to integrate other event mechanisms into libev and |
1123 | their use is somewhat advanced. This could be used, for example, to track |
1451 | their use is somewhat advanced. This could be used, for example, to track |
1124 | variable changes, implement your own watchers, integrate net-snmp or a |
1452 | variable changes, implement your own watchers, integrate net-snmp or a |
1125 | coroutine library and lots more.</p> |
1453 | coroutine library and lots more. They are also occasionally useful if |
|
|
1454 | you cache some data and want to flush it before blocking (for example, |
|
|
1455 | in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code> |
|
|
1456 | watcher).</p> |
1126 | <p>This is done by examining in each prepare call which file descriptors need |
1457 | <p>This is done by examining in each prepare call which file descriptors need |
1127 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1458 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1128 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1459 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1129 | provide just this functionality). Then, in the check watcher you check for |
1460 | provide just this functionality). Then, in the check watcher you check for |
1130 | any events that occured (by checking the pending status of all watchers |
1461 | any events that occured (by checking the pending status of all watchers |
… | |
… | |
1146 | <p>Initialises and configures the prepare or check watcher - they have no |
1477 | <p>Initialises and configures the prepare or check watcher - they have no |
1147 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1478 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1148 | macros, but using them is utterly, utterly and completely pointless.</p> |
1479 | macros, but using them is utterly, utterly and completely pointless.</p> |
1149 | </dd> |
1480 | </dd> |
1150 | </dl> |
1481 | </dl> |
1151 | <p>Example: *TODO*.</p> |
1482 | <p>Example: To include a library such as adns, you would add IO watchers |
|
|
1483 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1484 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1485 | pseudo-code only of course:</p> |
|
|
1486 | <pre> static ev_io iow [nfd]; |
|
|
1487 | static ev_timer tw; |
1152 | |
1488 | |
|
|
1489 | static void |
|
|
1490 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1491 | { |
|
|
1492 | // set the relevant poll flags |
|
|
1493 | // could also call adns_processreadable etc. here |
|
|
1494 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1495 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1496 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1497 | } |
1153 | |
1498 | |
|
|
1499 | // create io watchers for each fd and a timer before blocking |
|
|
1500 | static void |
|
|
1501 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1502 | { |
|
|
1503 | int timeout = 3600000; |
|
|
1504 | struct pollfd fds [nfd]; |
|
|
1505 | // actual code will need to loop here and realloc etc. |
|
|
1506 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1154 | |
1507 | |
|
|
1508 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1509 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1510 | ev_timer_start (loop, &tw); |
1155 | |
1511 | |
|
|
1512 | // create on ev_io per pollfd |
|
|
1513 | for (int i = 0; i < nfd; ++i) |
|
|
1514 | { |
|
|
1515 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1516 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1517 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1156 | |
1518 | |
|
|
1519 | fds [i].revents = 0; |
|
|
1520 | iow [i].data = fds + i; |
|
|
1521 | ev_io_start (loop, iow + i); |
|
|
1522 | } |
|
|
1523 | } |
|
|
1524 | |
|
|
1525 | // stop all watchers after blocking |
|
|
1526 | static void |
|
|
1527 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1528 | { |
|
|
1529 | ev_timer_stop (loop, &tw); |
|
|
1530 | |
|
|
1531 | for (int i = 0; i < nfd; ++i) |
|
|
1532 | ev_io_stop (loop, iow + i); |
|
|
1533 | |
|
|
1534 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1535 | } |
|
|
1536 | |
|
|
1537 | |
|
|
1538 | |
|
|
1539 | |
|
|
1540 | </pre> |
|
|
1541 | |
1157 | </div> |
1542 | </div> |
1158 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> |
1543 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2> |
1159 | <div id="code_ev_embed_code_when_one_backend_-2"> |
1544 | <div id="code_ev_embed_code_when_one_backend_-2"> |
1160 | <p>This is a rather advanced watcher type that lets you embed one event loop |
1545 | <p>This is a rather advanced watcher type that lets you embed one event loop |
1161 | into another (currently only <code>ev_io</code> events are supported in the embedded |
1546 | into another (currently only <code>ev_io</code> events are supported in the embedded |
1162 | loop, other types of watchers might be handled in a delayed or incorrect |
1547 | loop, other types of watchers might be handled in a delayed or incorrect |
1163 | fashion and must not be used).</p> |
1548 | fashion and must not be used).</p> |
… | |
… | |
1231 | <dd> |
1616 | <dd> |
1232 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
1617 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
1233 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
1618 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
1234 | apropriate way for embedded loops.</p> |
1619 | apropriate way for embedded loops.</p> |
1235 | </dd> |
1620 | </dd> |
|
|
1621 | <dt>struct ev_loop *loop [read-only]</dt> |
|
|
1622 | <dd> |
|
|
1623 | <p>The embedded event loop.</p> |
|
|
1624 | </dd> |
1236 | </dl> |
1625 | </dl> |
1237 | |
1626 | |
1238 | |
1627 | |
1239 | |
1628 | |
1240 | |
1629 | |
1241 | |
1630 | |
1242 | </div> |
1631 | </div> |
1243 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1632 | <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> |
|
|
1633 | <div id="code_ev_fork_code_the_audacity_to_re-2"> |
|
|
1634 | <p>Fork watchers are called when a <code>fork ()</code> was detected (usually because |
|
|
1635 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1636 | <code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the |
|
|
1637 | event loop blocks next and before <code>ev_check</code> watchers are being called, |
|
|
1638 | and only in the child after the fork. If whoever good citizen calling |
|
|
1639 | <code>ev_default_fork</code> cheats and calls it in the wrong process, the fork |
|
|
1640 | handlers will be invoked, too, of course.</p> |
|
|
1641 | <dl> |
|
|
1642 | <dt>ev_fork_init (ev_signal *, callback)</dt> |
|
|
1643 | <dd> |
|
|
1644 | <p>Initialises and configures the fork watcher - it has no parameters of any |
|
|
1645 | kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless, |
|
|
1646 | believe me.</p> |
|
|
1647 | </dd> |
|
|
1648 | </dl> |
|
|
1649 | |
|
|
1650 | |
|
|
1651 | |
|
|
1652 | |
|
|
1653 | |
|
|
1654 | </div> |
|
|
1655 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1> |
1244 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1656 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1245 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1657 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1246 | <dl> |
1658 | <dl> |
1247 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1659 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1248 | <dd> |
1660 | <dd> |
… | |
… | |
1295 | |
1707 | |
1296 | |
1708 | |
1297 | |
1709 | |
1298 | |
1710 | |
1299 | </div> |
1711 | </div> |
1300 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1712 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1> |
1301 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1713 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1302 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1714 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1303 | emulate the internals of libevent, so here are some usage hints:</p> |
1715 | emulate the internals of libevent, so here are some usage hints:</p> |
1304 | <dl> |
1716 | <dl> |
1305 | <dt>* Use it by including <event.h>, as usual.</dt> |
1717 | <dt>* Use it by including <event.h>, as usual.</dt> |
… | |
… | |
1315 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1727 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1316 | to use the libev header file and library.</dt> |
1728 | to use the libev header file and library.</dt> |
1317 | </dl> |
1729 | </dl> |
1318 | |
1730 | |
1319 | </div> |
1731 | </div> |
1320 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1732 | <h1 id="C_SUPPORT">C++ SUPPORT</h1> |
1321 | <div id="C_SUPPORT_CONTENT"> |
1733 | <div id="C_SUPPORT_CONTENT"> |
1322 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1734 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1323 | you to use some convinience methods to start/stop watchers and also change |
1735 | you to use some convinience methods to start/stop watchers and also change |
1324 | the callback model to a model using method callbacks on objects.</p> |
1736 | the callback model to a model using method callbacks on objects.</p> |
1325 | <p>To use it,</p> |
1737 | <p>To use it,</p> |
1326 | <pre> #include <ev++.h> |
1738 | <pre> #include <ev++.h> |
1327 | |
1739 | |
1328 | </pre> |
1740 | </pre> |
1329 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
1741 | <p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many |
1330 | and puts all of its definitions (many of them macros) into the global |
1742 | of them macros) into the global namespace. All C++ specific things are |
1331 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
1743 | put into the <code>ev</code> namespace. It should support all the same embedding |
1332 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
1744 | options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p> |
1333 | <code>EV_MULTIPLICITY</code>.</p> |
1745 | <p>Care has been taken to keep the overhead low. The only data member added |
|
|
1746 | to the C-style watchers is the event loop the watcher is associated with |
|
|
1747 | (or no additional members at all if you disable <code>EV_MULTIPLICITY</code> when |
|
|
1748 | embedding libev).</p> |
|
|
1749 | <p>Currently, functions and static and non-static member functions can be |
|
|
1750 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1751 | need one additional pointer for context. If you need support for other |
|
|
1752 | types of functors please contact the author (preferably after implementing |
|
|
1753 | it).</p> |
1334 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1754 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
1335 | <dl> |
1755 | <dl> |
1336 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1756 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
1337 | <dd> |
1757 | <dd> |
1338 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
1758 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
… | |
… | |
1349 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1769 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
1350 | defines by many implementations.</p> |
1770 | defines by many implementations.</p> |
1351 | <p>All of those classes have these methods:</p> |
1771 | <p>All of those classes have these methods:</p> |
1352 | <p> |
1772 | <p> |
1353 | <dl> |
1773 | <dl> |
1354 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
1774 | <dt>ev::TYPE::TYPE ()</dt> |
1355 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
1775 | <dt>ev::TYPE::TYPE (struct ev_loop *)</dt> |
1356 | <dt>ev::TYPE::~TYPE</dt> |
1776 | <dt>ev::TYPE::~TYPE</dt> |
1357 | <dd> |
1777 | <dd> |
1358 | <p>The constructor takes a pointer to an object and a method pointer to |
1778 | <p>The constructor (optionally) takes an event loop to associate the watcher |
1359 | the event handler callback to call in this class. The constructor calls |
1779 | with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p> |
1360 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
1780 | <p>The constructor calls <code>ev_init</code> for you, which means you have to call the |
1361 | before starting it. If you do not specify a loop then the constructor |
1781 | <code>set</code> method before starting it.</p> |
1362 | automatically associates the default loop with this watcher.</p> |
1782 | <p>It will not set a callback, however: You have to call the templated <code>set</code> |
|
|
1783 | method to set a callback before you can start the watcher.</p> |
|
|
1784 | <p>(The reason why you have to use a method is a limitation in C++ which does |
|
|
1785 | not allow explicit template arguments for constructors).</p> |
1363 | <p>The destructor automatically stops the watcher if it is active.</p> |
1786 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1787 | </dd> |
|
|
1788 | <dt>w->set<class, &class::method> (object *)</dt> |
|
|
1789 | <dd> |
|
|
1790 | <p>This method sets the callback method to call. The method has to have a |
|
|
1791 | signature of <code>void (*)(ev_TYPE &, int)</code>, it receives the watcher as |
|
|
1792 | first argument and the <code>revents</code> as second. The object must be given as |
|
|
1793 | parameter and is stored in the <code>data</code> member of the watcher.</p> |
|
|
1794 | <p>This method synthesizes efficient thunking code to call your method from |
|
|
1795 | the C callback that libev requires. If your compiler can inline your |
|
|
1796 | callback (i.e. it is visible to it at the place of the <code>set</code> call and |
|
|
1797 | your compiler is good :), then the method will be fully inlined into the |
|
|
1798 | thunking function, making it as fast as a direct C callback.</p> |
|
|
1799 | <p>Example: simple class declaration and watcher initialisation</p> |
|
|
1800 | <pre> struct myclass |
|
|
1801 | { |
|
|
1802 | void io_cb (ev::io &w, int revents) { } |
|
|
1803 | } |
|
|
1804 | |
|
|
1805 | myclass obj; |
|
|
1806 | ev::io iow; |
|
|
1807 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1808 | |
|
|
1809 | </pre> |
|
|
1810 | </dd> |
|
|
1811 | <dt>w->set (void (*function)(watcher &w, int), void *data = 0)</dt> |
|
|
1812 | <dd> |
|
|
1813 | <p>Also sets a callback, but uses a static method or plain function as |
|
|
1814 | callback. The optional <code>data</code> argument will be stored in the watcher's |
|
|
1815 | <code>data</code> member and is free for you to use.</p> |
|
|
1816 | <p>See the method-<code>set</code> above for more details.</p> |
1364 | </dd> |
1817 | </dd> |
1365 | <dt>w->set (struct ev_loop *)</dt> |
1818 | <dt>w->set (struct ev_loop *)</dt> |
1366 | <dd> |
1819 | <dd> |
1367 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
1820 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
1368 | do this when the watcher is inactive (and not pending either).</p> |
1821 | do this when the watcher is inactive (and not pending either).</p> |
1369 | </dd> |
1822 | </dd> |
1370 | <dt>w->set ([args])</dt> |
1823 | <dt>w->set ([args])</dt> |
1371 | <dd> |
1824 | <dd> |
1372 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
1825 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
1373 | called at least once. Unlike the C counterpart, an active watcher gets |
1826 | called at least once. Unlike the C counterpart, an active watcher gets |
1374 | automatically stopped and restarted.</p> |
1827 | automatically stopped and restarted when reconfiguring it with this |
|
|
1828 | method.</p> |
1375 | </dd> |
1829 | </dd> |
1376 | <dt>w->start ()</dt> |
1830 | <dt>w->start ()</dt> |
1377 | <dd> |
1831 | <dd> |
1378 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
1832 | <p>Starts the watcher. Note that there is no <code>loop</code> argument, as the |
1379 | constructor already takes the loop.</p> |
1833 | constructor already stores the event loop.</p> |
1380 | </dd> |
1834 | </dd> |
1381 | <dt>w->stop ()</dt> |
1835 | <dt>w->stop ()</dt> |
1382 | <dd> |
1836 | <dd> |
1383 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1837 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
1384 | </dd> |
1838 | </dd> |
… | |
… | |
1388 | <code>ev_TYPE_again</code> function.</p> |
1842 | <code>ev_TYPE_again</code> function.</p> |
1389 | </dd> |
1843 | </dd> |
1390 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
1844 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
1391 | <dd> |
1845 | <dd> |
1392 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
1846 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
|
|
1847 | </dd> |
|
|
1848 | <dt>w->update () <code>ev::stat</code> only</dt> |
|
|
1849 | <dd> |
|
|
1850 | <p>Invokes <code>ev_stat_stat</code>.</p> |
1393 | </dd> |
1851 | </dd> |
1394 | </dl> |
1852 | </dl> |
1395 | </p> |
1853 | </p> |
1396 | </dd> |
1854 | </dd> |
1397 | </dl> |
1855 | </dl> |
… | |
… | |
1404 | |
1862 | |
1405 | myclass (); |
1863 | myclass (); |
1406 | } |
1864 | } |
1407 | |
1865 | |
1408 | myclass::myclass (int fd) |
1866 | myclass::myclass (int fd) |
1409 | : io (this, &myclass::io_cb), |
|
|
1410 | idle (this, &myclass::idle_cb) |
|
|
1411 | { |
1867 | { |
|
|
1868 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1869 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1870 | |
1412 | io.start (fd, ev::READ); |
1871 | io.start (fd, ev::READ); |
1413 | } |
1872 | } |
1414 | |
1873 | |
1415 | </pre> |
|
|
1416 | |
1874 | |
|
|
1875 | |
|
|
1876 | |
|
|
1877 | </pre> |
|
|
1878 | |
1417 | </div> |
1879 | </div> |
1418 | <h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1880 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
|
|
1881 | <div id="MACRO_MAGIC_CONTENT"> |
|
|
1882 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1883 | <code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and |
|
|
1884 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
|
|
1885 | <p>To make it easier to write programs that cope with either variant, the |
|
|
1886 | following macros are defined:</p> |
|
|
1887 | <dl> |
|
|
1888 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
|
|
1889 | <dd> |
|
|
1890 | <p>This provides the loop <i>argument</i> for functions, if one is required ("ev |
|
|
1891 | loop argument"). The <code>EV_A</code> form is used when this is the sole argument, |
|
|
1892 | <code>EV_A_</code> is used when other arguments are following. Example:</p> |
|
|
1893 | <pre> ev_unref (EV_A); |
|
|
1894 | ev_timer_add (EV_A_ watcher); |
|
|
1895 | ev_loop (EV_A_ 0); |
|
|
1896 | |
|
|
1897 | </pre> |
|
|
1898 | <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope, |
|
|
1899 | which is often provided by the following macro.</p> |
|
|
1900 | </dd> |
|
|
1901 | <dt><code>EV_P</code>, <code>EV_P_</code></dt> |
|
|
1902 | <dd> |
|
|
1903 | <p>This provides the loop <i>parameter</i> for functions, if one is required ("ev |
|
|
1904 | loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter, |
|
|
1905 | <code>EV_P_</code> is used when other parameters are following. Example:</p> |
|
|
1906 | <pre> // this is how ev_unref is being declared |
|
|
1907 | static void ev_unref (EV_P); |
|
|
1908 | |
|
|
1909 | // this is how you can declare your typical callback |
|
|
1910 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1911 | |
|
|
1912 | </pre> |
|
|
1913 | <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite |
|
|
1914 | suitable for use with <code>EV_A</code>.</p> |
|
|
1915 | </dd> |
|
|
1916 | <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt> |
|
|
1917 | <dd> |
|
|
1918 | <p>Similar to the other two macros, this gives you the value of the default |
|
|
1919 | loop, if multiple loops are supported ("ev loop default").</p> |
|
|
1920 | </dd> |
|
|
1921 | </dl> |
|
|
1922 | <p>Example: Declare and initialise a check watcher, utilising the above |
|
|
1923 | macros so it will work regardless of whether multiple loops are supported |
|
|
1924 | or not.</p> |
|
|
1925 | <pre> static void |
|
|
1926 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1927 | { |
|
|
1928 | ev_check_stop (EV_A_ w); |
|
|
1929 | } |
|
|
1930 | |
|
|
1931 | ev_check check; |
|
|
1932 | ev_check_init (&check, check_cb); |
|
|
1933 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1934 | ev_loop (EV_DEFAULT_ 0); |
|
|
1935 | |
|
|
1936 | </pre> |
|
|
1937 | |
|
|
1938 | </div> |
|
|
1939 | <h1 id="EMBEDDING">EMBEDDING</h1> |
1419 | <div id="EMBEDDING_CONTENT"> |
1940 | <div id="EMBEDDING_CONTENT"> |
1420 | <p>Libev can (and often is) directly embedded into host |
1941 | <p>Libev can (and often is) directly embedded into host |
1421 | applications. Examples of applications that embed it include the Deliantra |
1942 | applications. Examples of applications that embed it include the Deliantra |
1422 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1943 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1423 | and rxvt-unicode.</p> |
1944 | and rxvt-unicode.</p> |
… | |
… | |
1460 | ev_vars.h |
1981 | ev_vars.h |
1461 | ev_wrap.h |
1982 | ev_wrap.h |
1462 | |
1983 | |
1463 | ev_win32.c required on win32 platforms only |
1984 | ev_win32.c required on win32 platforms only |
1464 | |
1985 | |
1465 | ev_select.c only when select backend is enabled (which is is by default) |
1986 | ev_select.c only when select backend is enabled (which is enabled by default) |
1466 | ev_poll.c only when poll backend is enabled (disabled by default) |
1987 | ev_poll.c only when poll backend is enabled (disabled by default) |
1467 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1988 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1468 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1989 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1469 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1990 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1470 | |
1991 | |
1471 | </pre> |
1992 | </pre> |
1472 | <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need |
1993 | <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need |
1473 | to compile a single file.</p> |
1994 | to compile this single file.</p> |
1474 | |
1995 | |
1475 | </div> |
1996 | </div> |
1476 | <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> |
1997 | <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> |
1477 | <div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> |
1998 | <div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> |
1478 | <p>To include the libevent compatibility API, also include:</p> |
1999 | <p>To include the libevent compatibility API, also include:</p> |
… | |
… | |
1493 | </div> |
2014 | </div> |
1494 | <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> |
2015 | <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> |
1495 | <div id="AUTOCONF_SUPPORT_CONTENT"> |
2016 | <div id="AUTOCONF_SUPPORT_CONTENT"> |
1496 | <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in |
2017 | <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in |
1497 | whatever way you want, you can also <code>m4_include([libev.m4])</code> in your |
2018 | whatever way you want, you can also <code>m4_include([libev.m4])</code> in your |
1498 | <cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> off. <cite>ev.c</cite> will then include |
2019 | <cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then |
1499 | <cite>config.h</cite> and configure itself accordingly.</p> |
2020 | include <cite>config.h</cite> and configure itself accordingly.</p> |
1500 | <p>For this of course you need the m4 file:</p> |
2021 | <p>For this of course you need the m4 file:</p> |
1501 | <pre> libev.m4 |
2022 | <pre> libev.m4 |
1502 | |
2023 | |
1503 | </pre> |
2024 | </pre> |
1504 | |
2025 | |
… | |
… | |
1597 | </dd> |
2118 | </dd> |
1598 | <dt>EV_USE_DEVPOLL</dt> |
2119 | <dt>EV_USE_DEVPOLL</dt> |
1599 | <dd> |
2120 | <dd> |
1600 | <p>reserved for future expansion, works like the USE symbols above.</p> |
2121 | <p>reserved for future expansion, works like the USE symbols above.</p> |
1601 | </dd> |
2122 | </dd> |
|
|
2123 | <dt>EV_USE_INOTIFY</dt> |
|
|
2124 | <dd> |
|
|
2125 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify |
|
|
2126 | interface to speed up <code>ev_stat</code> watchers. Its actual availability will |
|
|
2127 | be detected at runtime.</p> |
|
|
2128 | </dd> |
1602 | <dt>EV_H</dt> |
2129 | <dt>EV_H</dt> |
1603 | <dd> |
2130 | <dd> |
1604 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
2131 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
1605 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
2132 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
1606 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
2133 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
… | |
… | |
1629 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2156 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
1630 | additional independent event loops. Otherwise there will be no support |
2157 | additional independent event loops. Otherwise there will be no support |
1631 | for multiple event loops and there is no first event loop pointer |
2158 | for multiple event loops and there is no first event loop pointer |
1632 | argument. Instead, all functions act on the single default loop.</p> |
2159 | argument. Instead, all functions act on the single default loop.</p> |
1633 | </dd> |
2160 | </dd> |
1634 | <dt>EV_PERIODICS</dt> |
2161 | <dt>EV_MINPRI</dt> |
|
|
2162 | <dt>EV_MAXPRI</dt> |
|
|
2163 | <dd> |
|
|
2164 | <p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to |
|
|
2165 | <code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can |
|
|
2166 | provide for more priorities by overriding those symbols (usually defined |
|
|
2167 | to be <code>-2</code> and <code>2</code>, respectively).</p> |
|
|
2168 | <p>When doing priority-based operations, libev usually has to linearly search |
|
|
2169 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2170 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2171 | fine.</p> |
|
|
2172 | <p>If your embedding app does not need any priorities, defining these both to |
|
|
2173 | <code>0</code> will save some memory and cpu.</p> |
1635 | <dd> |
2174 | </dd> |
|
|
2175 | <dt>EV_PERIODIC_ENABLE</dt> |
|
|
2176 | <dd> |
1636 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported, |
2177 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
1637 | otherwise not. This saves a few kb of code.</p> |
2178 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2179 | code.</p> |
|
|
2180 | </dd> |
|
|
2181 | <dt>EV_IDLE_ENABLE</dt> |
|
|
2182 | <dd> |
|
|
2183 | <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If |
|
|
2184 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2185 | code.</p> |
|
|
2186 | </dd> |
|
|
2187 | <dt>EV_EMBED_ENABLE</dt> |
|
|
2188 | <dd> |
|
|
2189 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
|
|
2190 | defined to be <code>0</code>, then they are not.</p> |
|
|
2191 | </dd> |
|
|
2192 | <dt>EV_STAT_ENABLE</dt> |
|
|
2193 | <dd> |
|
|
2194 | <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If |
|
|
2195 | defined to be <code>0</code>, then they are not.</p> |
|
|
2196 | </dd> |
|
|
2197 | <dt>EV_FORK_ENABLE</dt> |
|
|
2198 | <dd> |
|
|
2199 | <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If |
|
|
2200 | defined to be <code>0</code>, then they are not.</p> |
|
|
2201 | </dd> |
|
|
2202 | <dt>EV_MINIMAL</dt> |
|
|
2203 | <dd> |
|
|
2204 | <p>If you need to shave off some kilobytes of code at the expense of some |
|
|
2205 | speed, define this symbol to <code>1</code>. Currently only used for gcc to override |
|
|
2206 | some inlining decisions, saves roughly 30% codesize of amd64.</p> |
|
|
2207 | </dd> |
|
|
2208 | <dt>EV_PID_HASHSIZE</dt> |
|
|
2209 | <dd> |
|
|
2210 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
|
|
2211 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
|
|
2212 | than enough. If you need to manage thousands of children you might want to |
|
|
2213 | increase this value (<i>must</i> be a power of two).</p> |
|
|
2214 | </dd> |
|
|
2215 | <dt>EV_INOTIFY_HASHSIZE</dt> |
|
|
2216 | <dd> |
|
|
2217 | <p><code>ev_staz</code> watchers use a small hash table to distribute workload by |
|
|
2218 | inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), |
|
|
2219 | usually more than enough. If you need to manage thousands of <code>ev_stat</code> |
|
|
2220 | watchers you might want to increase this value (<i>must</i> be a power of |
|
|
2221 | two).</p> |
1638 | </dd> |
2222 | </dd> |
1639 | <dt>EV_COMMON</dt> |
2223 | <dt>EV_COMMON</dt> |
1640 | <dd> |
2224 | <dd> |
1641 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2225 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
1642 | this macro to a something else you can include more and other types of |
2226 | this macro to a something else you can include more and other types of |
… | |
… | |
1647 | SV *self; /* contains this struct */ \ |
2231 | SV *self; /* contains this struct */ \ |
1648 | SV *cb_sv, *fh /* note no trailing ";" */ |
2232 | SV *cb_sv, *fh /* note no trailing ";" */ |
1649 | |
2233 | |
1650 | </pre> |
2234 | </pre> |
1651 | </dd> |
2235 | </dd> |
1652 | <dt>EV_CB_DECLARE(type)</dt> |
2236 | <dt>EV_CB_DECLARE (type)</dt> |
1653 | <dt>EV_CB_INVOKE(watcher,revents)</dt> |
2237 | <dt>EV_CB_INVOKE (watcher, revents)</dt> |
1654 | <dt>ev_set_cb(ev,cb)</dt> |
2238 | <dt>ev_set_cb (ev, cb)</dt> |
1655 | <dd> |
2239 | <dd> |
1656 | <p>Can be used to change the callback member declaration in each watcher, |
2240 | <p>Can be used to change the callback member declaration in each watcher, |
1657 | and the way callbacks are invoked and set. Must expand to a struct member |
2241 | and the way callbacks are invoked and set. Must expand to a struct member |
1658 | definition and a statement, respectively. See the <cite>ev.v</cite> header file for |
2242 | definition and a statement, respectively. See the <cite>ev.v</cite> header file for |
1659 | their default definitions. One possible use for overriding these is to |
2243 | their default definitions. One possible use for overriding these is to |
1660 | avoid the ev_loop pointer as first argument in all cases, or to use method |
2244 | avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use |
1661 | calls instead of plain function calls in C++.</p> |
2245 | method calls instead of plain function calls in C++.</p> |
1662 | |
2246 | |
1663 | </div> |
2247 | </div> |
1664 | <h2 id="EXAMPLES">EXAMPLES</h2> |
2248 | <h2 id="EXAMPLES">EXAMPLES</h2> |
1665 | <div id="EXAMPLES_CONTENT"> |
2249 | <div id="EXAMPLES_CONTENT"> |
1666 | <p>For a real-world example of a program the includes libev |
2250 | <p>For a real-world example of a program the includes libev |
… | |
… | |
1669 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2253 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
1670 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2254 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
1671 | will be compiled. It is pretty complex because it provides its own header |
2255 | will be compiled. It is pretty complex because it provides its own header |
1672 | file.</p> |
2256 | file.</p> |
1673 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2257 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
1674 | that everybody includes and which overrides some autoconf choices:</p> |
2258 | that everybody includes and which overrides some configure choices:</p> |
|
|
2259 | <pre> #define EV_MINIMAL 1 |
1675 | <pre> #define EV_USE_POLL 0 |
2260 | #define EV_USE_POLL 0 |
1676 | #define EV_MULTIPLICITY 0 |
2261 | #define EV_MULTIPLICITY 0 |
1677 | #define EV_PERIODICS 0 |
2262 | #define EV_PERIODIC_ENABLE 0 |
|
|
2263 | #define EV_STAT_ENABLE 0 |
|
|
2264 | #define EV_FORK_ENABLE 0 |
1678 | #define EV_CONFIG_H <config.h> |
2265 | #define EV_CONFIG_H <config.h> |
|
|
2266 | #define EV_MINPRI 0 |
|
|
2267 | #define EV_MAXPRI 0 |
1679 | |
2268 | |
1680 | #include "ev++.h" |
2269 | #include "ev++.h" |
1681 | |
2270 | |
1682 | </pre> |
2271 | </pre> |
1683 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
2272 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
1684 | <pre> #include "ev_cpp.h" |
2273 | <pre> #include "ev_cpp.h" |
1685 | #include "ev.c" |
2274 | #include "ev.c" |
1686 | |
2275 | |
1687 | </pre> |
|
|
1688 | |
2276 | |
|
|
2277 | |
|
|
2278 | |
|
|
2279 | </pre> |
|
|
2280 | |
1689 | </div> |
2281 | </div> |
1690 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2282 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
|
|
2283 | <div id="COMPLEXITIES_CONTENT"> |
|
|
2284 | <p>In this section the complexities of (many of) the algorithms used inside |
|
|
2285 | libev will be explained. For complexity discussions about backends see the |
|
|
2286 | documentation for <code>ev_default_init</code>.</p> |
|
|
2287 | <p>All of the following are about amortised time: If an array needs to be |
|
|
2288 | extended, libev needs to realloc and move the whole array, but this |
|
|
2289 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2290 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2291 | it is much faster and asymptotically approaches constant time.</p> |
|
|
2292 | <p> |
|
|
2293 | <dl> |
|
|
2294 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
2295 | <dd> |
|
|
2296 | <p>This means that, when you have a watcher that triggers in one hour and |
|
|
2297 | there are 100 watchers that would trigger before that then inserting will |
|
|
2298 | have to skip those 100 watchers.</p> |
|
|
2299 | </dd> |
|
|
2300 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
2301 | <dd> |
|
|
2302 | <p>That means that for changing a timer costs less than removing/adding them |
|
|
2303 | as only the relative motion in the event queue has to be paid for.</p> |
|
|
2304 | </dd> |
|
|
2305 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
2306 | <dd> |
|
|
2307 | <p>These just add the watcher into an array or at the head of a list. |
|
|
2308 | =item Stopping check/prepare/idle watchers: O(1)</p> |
|
|
2309 | </dd> |
|
|
2310 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
|
|
2311 | <dd> |
|
|
2312 | <p>These watchers are stored in lists then need to be walked to find the |
|
|
2313 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2314 | have many watchers waiting for the same fd or signal).</p> |
|
|
2315 | </dd> |
|
|
2316 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
|
|
2317 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
2318 | <dd> |
|
|
2319 | <p>A change means an I/O watcher gets started or stopped, which requires |
|
|
2320 | libev to recalculate its status (and possibly tell the kernel).</p> |
|
|
2321 | </dd> |
|
|
2322 | <dt>Activating one watcher: O(1)</dt> |
|
|
2323 | <dt>Priority handling: O(number_of_priorities)</dt> |
|
|
2324 | <dd> |
|
|
2325 | <p>Priorities are implemented by allocating some space for each |
|
|
2326 | priority. When doing priority-based operations, libev usually has to |
|
|
2327 | linearly search all the priorities.</p> |
|
|
2328 | </dd> |
|
|
2329 | </dl> |
|
|
2330 | </p> |
|
|
2331 | |
|
|
2332 | |
|
|
2333 | |
|
|
2334 | |
|
|
2335 | |
|
|
2336 | </div> |
|
|
2337 | <h1 id="AUTHOR">AUTHOR</h1> |
1691 | <div id="AUTHOR_CONTENT"> |
2338 | <div id="AUTHOR_CONTENT"> |
1692 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2339 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1693 | |
2340 | |
1694 | </div> |
2341 | </div> |
1695 | </div></body> |
2342 | </div></body> |