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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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9 | <meta name="created" content="Mon Nov 26 11:20:35 2007" /> |
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12 | <body> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
15 | <h3 id="TOP">Index</h3> |
15 | <h3 id="TOP">Index</h3> |
16 | |
16 | |
17 | <ul><li><a href="#NAME">NAME</a></li> |
17 | <ul><li><a href="#NAME">NAME</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
18 | <li><a href="#SYNOPSIS">SYNOPSIS</a></li> |
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19 | <li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
24 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
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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 repeating 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_watch_out_for_pro"><code>ev_child</code> - watch out for process 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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56 | <li><a href="#AUTHOR">AUTHOR</a> |
60 | <li><a href="#AUTHOR">AUTHOR</a> |
57 | </li> |
61 | </li> |
58 | </ul><hr /> |
62 | </ul><hr /> |
59 | <!-- INDEX END --> |
63 | <!-- INDEX END --> |
60 | |
64 | |
61 | <h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> |
65 | <h1 id="NAME">NAME</h1> |
62 | <div id="NAME_CONTENT"> |
66 | <div id="NAME_CONTENT"> |
63 | <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> |
64 | |
68 | |
65 | </div> |
69 | </div> |
66 | <h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
70 | <h1 id="SYNOPSIS">SYNOPSIS</h1> |
67 | <div id="SYNOPSIS_CONTENT"> |
71 | <div id="SYNOPSIS_CONTENT"> |
68 | <pre> #include <ev.h> |
72 | <pre> #include <ev.h> |
69 | |
73 | |
70 | </pre> |
74 | </pre> |
71 | |
75 | |
72 | </div> |
76 | </div> |
73 | <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> |
74 | <div id="DESCRIPTION_CONTENT"> |
123 | <div id="DESCRIPTION_CONTENT"> |
75 | <p>Libev is an event loop: you register interest in certain events (such as a |
124 | <p>Libev is an event loop: you register interest in certain events (such as a |
76 | file descriptor being readable or a timeout occuring), and it will manage |
125 | file descriptor being readable or a timeout occuring), and it will manage |
77 | these event sources and provide your program with events.</p> |
126 | these event sources and provide your program with events.</p> |
78 | <p>To do this, it must take more or less complete control over your process |
127 | <p>To do this, it must take more or less complete control over your process |
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82 | watchers</i>, which are relatively small C structures you initialise with the |
131 | watchers</i>, which are relatively small C structures you initialise with the |
83 | details of the event, and then hand it over to libev by <i>starting</i> the |
132 | details of the event, and then hand it over to libev by <i>starting</i> the |
84 | watcher.</p> |
133 | watcher.</p> |
85 | |
134 | |
86 | </div> |
135 | </div> |
87 | <h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
136 | <h1 id="FEATURES">FEATURES</h1> |
88 | <div id="FEATURES_CONTENT"> |
137 | <div id="FEATURES_CONTENT"> |
89 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
138 | <p>Libev supports <code>select</code>, <code>poll</code>, the linux-specific <code>epoll</code>, the |
90 | kqueue mechanisms for file descriptor events, relative timers, absolute |
139 | bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms |
91 | timers with customised rescheduling, signal events, process status change |
140 | for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>), |
92 | events (related to SIGCHLD), and event watchers dealing with the event |
141 | absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous |
93 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
142 | signals (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and |
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143 | event watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
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144 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
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145 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
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146 | (<code>ev_fork</code>).</p> |
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147 | <p>It also is quite fast (see this |
94 | fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing |
148 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
95 | it to libevent for example).</p> |
149 | for example).</p> |
96 | |
150 | |
97 | </div> |
151 | </div> |
98 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
152 | <h1 id="CONVENTIONS">CONVENTIONS</h1> |
99 | <div id="CONVENTIONS_CONTENT"> |
153 | <div id="CONVENTIONS_CONTENT"> |
100 | <p>Libev is very configurable. In this manual the default configuration |
154 | <p>Libev is very configurable. In this manual the default configuration will |
101 | will be described, which supports multiple event loops. For more info |
155 | be described, which supports multiple event loops. For more info about |
102 | about various configuration options please have a look at the file |
156 | various configuration options please have a look at <strong>EMBED</strong> section in |
103 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
157 | this manual. If libev was configured without support for multiple event |
104 | support for multiple event loops, then all functions taking an initial |
158 | loops, then all functions taking an initial argument of name <code>loop</code> |
105 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
159 | (which is always of type <code>struct ev_loop *</code>) will not have this argument.</p> |
106 | will not have this argument.</p> |
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107 | |
160 | |
108 | </div> |
161 | </div> |
109 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
162 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1> |
110 | <div id="TIME_REPRESENTATION_CONTENT"> |
163 | <div id="TIME_REPRESENTATION_CONTENT"> |
111 | <p>Libev represents time as a single floating point number, representing the |
164 | <p>Libev represents time as a single floating point number, representing the |
112 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
165 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
113 | the beginning of 1970, details are complicated, don't ask). This type is |
166 | the beginning of 1970, details are complicated, don't ask). This type is |
114 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
167 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
115 | to the <code>double</code> type in C, and when you need to do any calculations on |
168 | to the <code>double</code> type in C, and when you need to do any calculations on |
116 | it, you should treat it as such.</p> |
169 | it, you should treat it as such.</p> |
117 | |
170 | |
118 | |
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119 | |
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120 | |
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121 | |
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122 | </div> |
171 | </div> |
123 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
172 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1> |
124 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
173 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
125 | <p>These functions can be called anytime, even before initialising the |
174 | <p>These functions can be called anytime, even before initialising the |
126 | library in any way.</p> |
175 | library in any way.</p> |
127 | <dl> |
176 | <dl> |
128 | <dt>ev_tstamp ev_time ()</dt> |
177 | <dt>ev_tstamp ev_time ()</dt> |
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141 | version of the library your program was compiled against.</p> |
190 | version of the library your program was compiled against.</p> |
142 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
191 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
143 | as this indicates an incompatible change. Minor versions are usually |
192 | as this indicates an incompatible change. Minor versions are usually |
144 | compatible to older versions, so a larger minor version alone is usually |
193 | compatible to older versions, so a larger minor version alone is usually |
145 | not a problem.</p> |
194 | not a problem.</p> |
146 | <p>Example: make sure we haven't accidentally been linked against the wrong |
195 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
147 | version:</p> |
196 | version.</p> |
148 | <pre> assert (("libev version mismatch", |
197 | <pre> assert (("libev version mismatch", |
149 | ev_version_major () == EV_VERSION_MAJOR |
198 | ev_version_major () == EV_VERSION_MAJOR |
150 | && ev_version_minor () >= EV_VERSION_MINOR)); |
199 | && ev_version_minor () >= EV_VERSION_MINOR)); |
151 | |
200 | |
152 | </pre> |
201 | </pre> |
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180 | might be supported on the current system, you would need to look at |
229 | might be supported on the current system, you would need to look at |
181 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
230 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
182 | recommended ones.</p> |
231 | recommended ones.</p> |
183 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
232 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
184 | </dd> |
233 | </dd> |
185 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
234 | <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt> |
186 | <dd> |
235 | <dd> |
187 | <p>Sets the allocation function to use (the prototype is similar to the |
236 | <p>Sets the allocation function to use (the prototype and semantics are |
188 | realloc C function, the semantics are identical). It is used to allocate |
237 | identical to the realloc C function). It is used to allocate and free |
189 | and free memory (no surprises here). If it returns zero when memory |
238 | memory (no surprises here). If it returns zero when memory needs to be |
190 | needs to be allocated, the library might abort or take some potentially |
239 | allocated, the library might abort or take some potentially destructive |
191 | destructive action. The default is your system realloc function.</p> |
240 | action. The default is your system realloc function.</p> |
192 | <p>You could override this function in high-availability programs to, say, |
241 | <p>You could override this function in high-availability programs to, say, |
193 | free some memory if it cannot allocate memory, to use a special allocator, |
242 | free some memory if it cannot allocate memory, to use a special allocator, |
194 | or even to sleep a while and retry until some memory is available.</p> |
243 | or even to sleep a while and retry until some memory is available.</p> |
195 | <p>Example: replace the libev allocator with one that waits a bit and then |
244 | <p>Example: Replace the libev allocator with one that waits a bit and then |
196 | retries: better than mine).</p> |
245 | retries).</p> |
197 | <pre> static void * |
246 | <pre> static void * |
198 | persistent_realloc (void *ptr, long size) |
247 | persistent_realloc (void *ptr, size_t size) |
199 | { |
248 | { |
200 | for (;;) |
249 | for (;;) |
201 | { |
250 | { |
202 | void *newptr = realloc (ptr, size); |
251 | void *newptr = realloc (ptr, size); |
203 | |
252 | |
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220 | indicating the system call or subsystem causing the problem. If this |
269 | indicating the system call or subsystem causing the problem. If this |
221 | callback is set, then libev will expect it to remedy the sitution, no |
270 | callback is set, then libev will expect it to remedy the sitution, no |
222 | matter what, when it returns. That is, libev will generally retry the |
271 | matter what, when it returns. That is, libev will generally retry the |
223 | requested operation, or, if the condition doesn't go away, do bad stuff |
272 | requested operation, or, if the condition doesn't go away, do bad stuff |
224 | (such as abort).</p> |
273 | (such as abort).</p> |
225 | <p>Example: do the same thing as libev does internally:</p> |
274 | <p>Example: This is basically the same thing that libev does internally, too.</p> |
226 | <pre> static void |
275 | <pre> static void |
227 | fatal_error (const char *msg) |
276 | fatal_error (const char *msg) |
228 | { |
277 | { |
229 | perror (msg); |
278 | perror (msg); |
230 | abort (); |
279 | abort (); |
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236 | </pre> |
285 | </pre> |
237 | </dd> |
286 | </dd> |
238 | </dl> |
287 | </dl> |
239 | |
288 | |
240 | </div> |
289 | </div> |
241 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
290 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1> |
242 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
291 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
243 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
292 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
244 | types of such loops, the <i>default</i> loop, which supports signals and child |
293 | types of such loops, the <i>default</i> loop, which supports signals and child |
245 | events, and dynamically created loops which do not.</p> |
294 | events, and dynamically created loops which do not.</p> |
246 | <p>If you use threads, a common model is to run the default event loop |
295 | <p>If you use threads, a common model is to run the default event loop |
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366 | <dd> |
415 | <dd> |
367 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
416 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
368 | always distinct from the default loop. Unlike the default loop, it cannot |
417 | always distinct from the default loop. Unlike the default loop, it cannot |
369 | handle signal and child watchers, and attempts to do so will be greeted by |
418 | handle signal and child watchers, and attempts to do so will be greeted by |
370 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
419 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
371 | <p>Example: try to create a event loop that uses epoll and nothing else.</p> |
420 | <p>Example: Try to create a event loop that uses epoll and nothing else.</p> |
372 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
421 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
373 | if (!epoller) |
422 | if (!epoller) |
374 | fatal ("no epoll found here, maybe it hides under your chair"); |
423 | fatal ("no epoll found here, maybe it hides under your chair"); |
375 | |
424 | |
376 | </pre> |
425 | </pre> |
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469 | be handled here by queueing them when their watcher gets executed. |
518 | be handled here by queueing them when their watcher gets executed. |
470 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
519 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
471 | were used, return, otherwise continue with step *. |
520 | were used, return, otherwise continue with step *. |
472 | |
521 | |
473 | </pre> |
522 | </pre> |
474 | <p>Example: queue some jobs and then loop until no events are outsanding |
523 | <p>Example: Queue some jobs and then loop until no events are outsanding |
475 | anymore.</p> |
524 | anymore.</p> |
476 | <pre> ... queue jobs here, make sure they register event watchers as long |
525 | <pre> ... queue jobs here, make sure they register event watchers as long |
477 | ... as they still have work to do (even an idle watcher will do..) |
526 | ... as they still have work to do (even an idle watcher will do..) |
478 | ev_loop (my_loop, 0); |
527 | ev_loop (my_loop, 0); |
479 | ... jobs done. yeah! |
528 | ... jobs done. yeah! |
… | |
… | |
498 | example, libev itself uses this for its internal signal pipe: It is not |
547 | example, libev itself uses this for its internal signal pipe: It is not |
499 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
548 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
500 | no event watchers registered by it are active. It is also an excellent |
549 | no event watchers registered by it are active. It is also an excellent |
501 | way to do this for generic recurring timers or from within third-party |
550 | way to do this for generic recurring timers or from within third-party |
502 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
551 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
503 | <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> |
552 | <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code> |
504 | running when nothing else is active.</p> |
553 | running when nothing else is active.</p> |
505 | <pre> struct dv_signal exitsig; |
554 | <pre> struct ev_signal exitsig; |
506 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
555 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
507 | ev_signal_start (myloop, &exitsig); |
556 | ev_signal_start (loop, &exitsig); |
508 | evf_unref (myloop); |
557 | evf_unref (loop); |
509 | |
558 | |
510 | </pre> |
559 | </pre> |
511 | <p>Example: for some weird reason, unregister the above signal handler again.</p> |
560 | <p>Example: For some weird reason, unregister the above signal handler again.</p> |
512 | <pre> ev_ref (myloop); |
561 | <pre> ev_ref (loop); |
513 | ev_signal_stop (myloop, &exitsig); |
562 | ev_signal_stop (loop, &exitsig); |
514 | |
563 | |
515 | </pre> |
564 | </pre> |
516 | </dd> |
565 | </dd> |
517 | </dl> |
566 | </dl> |
518 | |
567 | |
519 | |
568 | |
520 | |
569 | |
521 | |
570 | |
522 | |
571 | |
523 | </div> |
572 | </div> |
524 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
573 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1> |
525 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
574 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
526 | <p>A watcher is a structure that you create and register to record your |
575 | <p>A watcher is a structure that you create and register to record your |
527 | interest in some event. For instance, if you want to wait for STDIN to |
576 | interest in some event. For instance, if you want to wait for STDIN to |
528 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
577 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
529 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
578 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
586 | </dd> |
635 | </dd> |
587 | <dt><code>EV_CHILD</code></dt> |
636 | <dt><code>EV_CHILD</code></dt> |
588 | <dd> |
637 | <dd> |
589 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
638 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
590 | </dd> |
639 | </dd> |
|
|
640 | <dt><code>EV_STAT</code></dt> |
|
|
641 | <dd> |
|
|
642 | <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p> |
|
|
643 | </dd> |
591 | <dt><code>EV_IDLE</code></dt> |
644 | <dt><code>EV_IDLE</code></dt> |
592 | <dd> |
645 | <dd> |
593 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
646 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
594 | </dd> |
647 | </dd> |
595 | <dt><code>EV_PREPARE</code></dt> |
648 | <dt><code>EV_PREPARE</code></dt> |
… | |
… | |
600 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
653 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
601 | received events. Callbacks of both watcher types can start and stop as |
654 | received events. Callbacks of both watcher types can start and stop as |
602 | many watchers as they want, and all of them will be taken into account |
655 | many watchers as they want, and all of them will be taken into account |
603 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
656 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
604 | <code>ev_loop</code> from blocking).</p> |
657 | <code>ev_loop</code> from blocking).</p> |
|
|
658 | </dd> |
|
|
659 | <dt><code>EV_EMBED</code></dt> |
|
|
660 | <dd> |
|
|
661 | <p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p> |
|
|
662 | </dd> |
|
|
663 | <dt><code>EV_FORK</code></dt> |
|
|
664 | <dd> |
|
|
665 | <p>The event loop has been resumed in the child process after fork (see |
|
|
666 | <code>ev_fork</code>).</p> |
605 | </dd> |
667 | </dd> |
606 | <dt><code>EV_ERROR</code></dt> |
668 | <dt><code>EV_ERROR</code></dt> |
607 | <dd> |
669 | <dd> |
608 | <p>An unspecified error has occured, the watcher has been stopped. This might |
670 | <p>An unspecified error has occured, the watcher has been stopped. This might |
609 | happen because the watcher could not be properly started because libev |
671 | happen because the watcher could not be properly started because libev |
… | |
… | |
729 | |
791 | |
730 | |
792 | |
731 | |
793 | |
732 | |
794 | |
733 | </div> |
795 | </div> |
734 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
796 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
735 | <div id="WATCHER_TYPES_CONTENT"> |
797 | <div id="WATCHER_TYPES_CONTENT"> |
736 | <p>This section describes each watcher in detail, but will not repeat |
798 | <p>This section describes each watcher in detail, but will not repeat |
737 | information given in the last section.</p> |
799 | information given in the last section. Any initialisation/set macros, |
|
|
800 | functions and members specific to the watcher type are explained.</p> |
|
|
801 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
|
|
802 | while the watcher is active, you can look at the member and expect some |
|
|
803 | sensible content, but you must not modify it (you can modify it while the |
|
|
804 | watcher is stopped to your hearts content), or <i>[read-write]</i>, which |
|
|
805 | means you can expect it to have some sensible content while the watcher |
|
|
806 | is active, but you can also modify it. Modifying it may not do something |
|
|
807 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
808 | not crash or malfunction in any way.</p> |
738 | |
809 | |
739 | |
810 | |
740 | |
811 | |
741 | |
812 | |
742 | |
813 | |
… | |
… | |
781 | <dd> |
852 | <dd> |
782 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
853 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
783 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
854 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
784 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
855 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
785 | </dd> |
856 | </dd> |
|
|
857 | <dt>int fd [read-only]</dt> |
|
|
858 | <dd> |
|
|
859 | <p>The file descriptor being watched.</p> |
|
|
860 | </dd> |
|
|
861 | <dt>int events [read-only]</dt> |
|
|
862 | <dd> |
|
|
863 | <p>The events being watched.</p> |
|
|
864 | </dd> |
786 | </dl> |
865 | </dl> |
787 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
866 | <p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
788 | readable, but only once. Since it is likely line-buffered, you could |
867 | readable, but only once. Since it is likely line-buffered, you could |
789 | attempt to read a whole line in the callback:</p> |
868 | attempt to read a whole line in the callback.</p> |
790 | <pre> static void |
869 | <pre> static void |
791 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
870 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
792 | { |
871 | { |
793 | ev_io_stop (loop, w); |
872 | ev_io_stop (loop, w); |
794 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
873 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
… | |
… | |
847 | repeating. The exact semantics are:</p> |
926 | repeating. The exact semantics are:</p> |
848 | <p>If the timer is started but nonrepeating, stop it.</p> |
927 | <p>If the timer is started but nonrepeating, stop it.</p> |
849 | <p>If the timer is repeating, either start it if necessary (with the repeat |
928 | <p>If the timer is repeating, either start it if necessary (with the repeat |
850 | value), or reset the running timer to the repeat value.</p> |
929 | value), or reset the running timer to the repeat value.</p> |
851 | <p>This sounds a bit complicated, but here is a useful and typical |
930 | <p>This sounds a bit complicated, but here is a useful and typical |
852 | example: Imagine you have a tcp connection and you want a so-called idle |
931 | example: Imagine you have a tcp connection and you want a so-called |
853 | timeout, that is, you want to be called when there have been, say, 60 |
932 | idle timeout, that is, you want to be called when there have been, |
854 | seconds of inactivity on the socket. The easiest way to do this is to |
933 | say, 60 seconds of inactivity on the socket. The easiest way to do |
855 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
934 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
856 | time you successfully read or write some data. If you go into an idle |
935 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
857 | state where you do not expect data to travel on the socket, you can stop |
936 | you go into an idle state where you do not expect data to travel on the |
858 | the timer, and again will automatically restart it if need be.</p> |
937 | socket, you can stop the timer, and again will automatically restart it if |
|
|
938 | need be.</p> |
|
|
939 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
|
|
940 | and only ever use the <code>repeat</code> value:</p> |
|
|
941 | <pre> ev_timer_init (timer, callback, 0., 5.); |
|
|
942 | ev_timer_again (loop, timer); |
|
|
943 | ... |
|
|
944 | timer->again = 17.; |
|
|
945 | ev_timer_again (loop, timer); |
|
|
946 | ... |
|
|
947 | timer->again = 10.; |
|
|
948 | ev_timer_again (loop, timer); |
|
|
949 | |
|
|
950 | </pre> |
|
|
951 | <p>This is more efficient then stopping/starting the timer eahc time you want |
|
|
952 | to modify its timeout value.</p> |
|
|
953 | </dd> |
|
|
954 | <dt>ev_tstamp repeat [read-write]</dt> |
|
|
955 | <dd> |
|
|
956 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
|
|
957 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
|
|
958 | which is also when any modifications are taken into account.</p> |
859 | </dd> |
959 | </dd> |
860 | </dl> |
960 | </dl> |
861 | <p>Example: create a timer that fires after 60 seconds.</p> |
961 | <p>Example: Create a timer that fires after 60 seconds.</p> |
862 | <pre> static void |
962 | <pre> static void |
863 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
963 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
864 | { |
964 | { |
865 | .. one minute over, w is actually stopped right here |
965 | .. one minute over, w is actually stopped right here |
866 | } |
966 | } |
… | |
… | |
868 | struct ev_timer mytimer; |
968 | struct ev_timer mytimer; |
869 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
969 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
870 | ev_timer_start (loop, &mytimer); |
970 | ev_timer_start (loop, &mytimer); |
871 | |
971 | |
872 | </pre> |
972 | </pre> |
873 | <p>Example: create a timeout timer that times out after 10 seconds of |
973 | <p>Example: Create a timeout timer that times out after 10 seconds of |
874 | inactivity.</p> |
974 | inactivity.</p> |
875 | <pre> static void |
975 | <pre> static void |
876 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
976 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
877 | { |
977 | { |
878 | .. ten seconds without any activity |
978 | .. ten seconds without any activity |
… | |
… | |
981 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1081 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
982 | when you changed some parameters or the reschedule callback would return |
1082 | when you changed some parameters or the reschedule callback would return |
983 | a different time than the last time it was called (e.g. in a crond like |
1083 | a different time than the last time it was called (e.g. in a crond like |
984 | program when the crontabs have changed).</p> |
1084 | program when the crontabs have changed).</p> |
985 | </dd> |
1085 | </dd> |
|
|
1086 | <dt>ev_tstamp interval [read-write]</dt> |
|
|
1087 | <dd> |
|
|
1088 | <p>The current interval value. Can be modified any time, but changes only |
|
|
1089 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
|
|
1090 | called.</p> |
|
|
1091 | </dd> |
|
|
1092 | <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt> |
|
|
1093 | <dd> |
|
|
1094 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
|
|
1095 | switched off. Can be changed any time, but changes only take effect when |
|
|
1096 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
|
|
1097 | </dd> |
986 | </dl> |
1098 | </dl> |
987 | <p>Example: call a callback every hour, or, more precisely, whenever the |
1099 | <p>Example: Call a callback every hour, or, more precisely, whenever the |
988 | system clock is divisible by 3600. The callback invocation times have |
1100 | system clock is divisible by 3600. The callback invocation times have |
989 | potentially a lot of jittering, but good long-term stability.</p> |
1101 | potentially a lot of jittering, but good long-term stability.</p> |
990 | <pre> static void |
1102 | <pre> static void |
991 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1103 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
992 | { |
1104 | { |
… | |
… | |
996 | struct ev_periodic hourly_tick; |
1108 | struct ev_periodic hourly_tick; |
997 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1109 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
998 | ev_periodic_start (loop, &hourly_tick); |
1110 | ev_periodic_start (loop, &hourly_tick); |
999 | |
1111 | |
1000 | </pre> |
1112 | </pre> |
1001 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
1113 | <p>Example: The same as above, but use a reschedule callback to do it:</p> |
1002 | <pre> #include <math.h> |
1114 | <pre> #include <math.h> |
1003 | |
1115 | |
1004 | static ev_tstamp |
1116 | static ev_tstamp |
1005 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1117 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1006 | { |
1118 | { |
… | |
… | |
1008 | } |
1120 | } |
1009 | |
1121 | |
1010 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1122 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1011 | |
1123 | |
1012 | </pre> |
1124 | </pre> |
1013 | <p>Example: call a callback every hour, starting now:</p> |
1125 | <p>Example: Call a callback every hour, starting now:</p> |
1014 | <pre> struct ev_periodic hourly_tick; |
1126 | <pre> struct ev_periodic hourly_tick; |
1015 | ev_periodic_init (&hourly_tick, clock_cb, |
1127 | ev_periodic_init (&hourly_tick, clock_cb, |
1016 | fmod (ev_now (loop), 3600.), 3600., 0); |
1128 | fmod (ev_now (loop), 3600.), 3600., 0); |
1017 | ev_periodic_start (loop, &hourly_tick); |
1129 | ev_periodic_start (loop, &hourly_tick); |
1018 | |
1130 | |
… | |
… | |
1039 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1151 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1040 | <dd> |
1152 | <dd> |
1041 | <p>Configures the watcher to trigger on the given signal number (usually one |
1153 | <p>Configures the watcher to trigger on the given signal number (usually one |
1042 | of the <code>SIGxxx</code> constants).</p> |
1154 | of the <code>SIGxxx</code> constants).</p> |
1043 | </dd> |
1155 | </dd> |
|
|
1156 | <dt>int signum [read-only]</dt> |
|
|
1157 | <dd> |
|
|
1158 | <p>The signal the watcher watches out for.</p> |
|
|
1159 | </dd> |
1044 | </dl> |
1160 | </dl> |
1045 | |
1161 | |
1046 | |
1162 | |
1047 | |
1163 | |
1048 | |
1164 | |
… | |
… | |
1061 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1177 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1062 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1178 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1063 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1179 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1064 | process causing the status change.</p> |
1180 | process causing the status change.</p> |
1065 | </dd> |
1181 | </dd> |
|
|
1182 | <dt>int pid [read-only]</dt> |
|
|
1183 | <dd> |
|
|
1184 | <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p> |
|
|
1185 | </dd> |
|
|
1186 | <dt>int rpid [read-write]</dt> |
|
|
1187 | <dd> |
|
|
1188 | <p>The process id that detected a status change.</p> |
|
|
1189 | </dd> |
|
|
1190 | <dt>int rstatus [read-write]</dt> |
|
|
1191 | <dd> |
|
|
1192 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
|
|
1193 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
|
|
1194 | </dd> |
1066 | </dl> |
1195 | </dl> |
1067 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
1196 | <p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p> |
1068 | <pre> static void |
1197 | <pre> static void |
1069 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1198 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1070 | { |
1199 | { |
1071 | ev_unloop (loop, EVUNLOOP_ALL); |
1200 | ev_unloop (loop, EVUNLOOP_ALL); |
1072 | } |
1201 | } |
1073 | |
1202 | |
1074 | struct ev_signal signal_watcher; |
1203 | struct ev_signal signal_watcher; |
1075 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1204 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1076 | ev_signal_start (loop, &sigint_cb); |
1205 | ev_signal_start (loop, &sigint_cb); |
|
|
1206 | |
|
|
1207 | |
|
|
1208 | |
|
|
1209 | |
|
|
1210 | </pre> |
|
|
1211 | |
|
|
1212 | </div> |
|
|
1213 | <h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2> |
|
|
1214 | <div id="code_ev_stat_code_did_the_file_attri-2"> |
|
|
1215 | <p>This watches a filesystem path for attribute changes. That is, it calls |
|
|
1216 | <code>stat</code> regularly (or when the OS says it changed) and sees if it changed |
|
|
1217 | compared to the last time, invoking the callback if it did.</p> |
|
|
1218 | <p>The path does not need to exist: changing from "path exists" to "path does |
|
|
1219 | not exist" is a status change like any other. The condition "path does |
|
|
1220 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
|
|
1221 | otherwise always forced to be at least one) and all the other fields of |
|
|
1222 | the stat buffer having unspecified contents.</p> |
|
|
1223 | <p>Since there is no standard to do this, the portable implementation simply |
|
|
1224 | calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You |
|
|
1225 | can specify a recommended polling interval for this case. If you specify |
|
|
1226 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
|
|
1227 | unspecified default</i> value will be used (which you can expect to be around |
|
|
1228 | five seconds, although this might change dynamically). Libev will also |
|
|
1229 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
|
|
1230 | usually overkill.</p> |
|
|
1231 | <p>This watcher type is not meant for massive numbers of stat watchers, |
|
|
1232 | as even with OS-supported change notifications, this can be |
|
|
1233 | resource-intensive.</p> |
|
|
1234 | <p>At the time of this writing, no specific OS backends are implemented, but |
|
|
1235 | if demand increases, at least a kqueue and inotify backend will be added.</p> |
|
|
1236 | <dl> |
|
|
1237 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
|
|
1238 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
|
|
1239 | <dd> |
|
|
1240 | <p>Configures the watcher to wait for status changes of the given |
|
|
1241 | <code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to |
|
|
1242 | be detected and should normally be specified as <code>0</code> to let libev choose |
|
|
1243 | a suitable value. The memory pointed to by <code>path</code> must point to the same |
|
|
1244 | path for as long as the watcher is active.</p> |
|
|
1245 | <p>The callback will be receive <code>EV_STAT</code> when a change was detected, |
|
|
1246 | relative to the attributes at the time the watcher was started (or the |
|
|
1247 | last change was detected).</p> |
|
|
1248 | </dd> |
|
|
1249 | <dt>ev_stat_stat (ev_stat *)</dt> |
|
|
1250 | <dd> |
|
|
1251 | <p>Updates the stat buffer immediately with new values. If you change the |
|
|
1252 | watched path in your callback, you could call this fucntion to avoid |
|
|
1253 | detecting this change (while introducing a race condition). Can also be |
|
|
1254 | useful simply to find out the new values.</p> |
|
|
1255 | </dd> |
|
|
1256 | <dt>ev_statdata attr [read-only]</dt> |
|
|
1257 | <dd> |
|
|
1258 | <p>The most-recently detected attributes of the file. Although the type is of |
|
|
1259 | <code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types |
|
|
1260 | suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there |
|
|
1261 | was some error while <code>stat</code>ing the file.</p> |
|
|
1262 | </dd> |
|
|
1263 | <dt>ev_statdata prev [read-only]</dt> |
|
|
1264 | <dd> |
|
|
1265 | <p>The previous attributes of the file. The callback gets invoked whenever |
|
|
1266 | <code>prev</code> != <code>attr</code>.</p> |
|
|
1267 | </dd> |
|
|
1268 | <dt>ev_tstamp interval [read-only]</dt> |
|
|
1269 | <dd> |
|
|
1270 | <p>The specified interval.</p> |
|
|
1271 | </dd> |
|
|
1272 | <dt>const char *path [read-only]</dt> |
|
|
1273 | <dd> |
|
|
1274 | <p>The filesystem path that is being watched.</p> |
|
|
1275 | </dd> |
|
|
1276 | </dl> |
|
|
1277 | <p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p> |
|
|
1278 | <pre> static void |
|
|
1279 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1280 | { |
|
|
1281 | /* /etc/passwd changed in some way */ |
|
|
1282 | if (w->attr.st_nlink) |
|
|
1283 | { |
|
|
1284 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1285 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1286 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1287 | } |
|
|
1288 | else |
|
|
1289 | /* you shalt not abuse printf for puts */ |
|
|
1290 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1291 | "if this is windows, they already arrived\n"); |
|
|
1292 | } |
|
|
1293 | |
|
|
1294 | ... |
|
|
1295 | ev_stat passwd; |
|
|
1296 | |
|
|
1297 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1298 | ev_stat_start (loop, &passwd); |
1077 | |
1299 | |
1078 | |
1300 | |
1079 | |
1301 | |
1080 | |
1302 | |
1081 | </pre> |
1303 | </pre> |
… | |
… | |
1102 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1324 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1103 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1325 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1104 | believe me.</p> |
1326 | believe me.</p> |
1105 | </dd> |
1327 | </dd> |
1106 | </dl> |
1328 | </dl> |
1107 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
1329 | <p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the |
1108 | callback, free it. Alos, use no error checking, as usual.</p> |
1330 | callback, free it. Also, use no error checking, as usual.</p> |
1109 | <pre> static void |
1331 | <pre> static void |
1110 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1332 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1111 | { |
1333 | { |
1112 | free (w); |
1334 | free (w); |
1113 | // now do something you wanted to do when the program has |
1335 | // now do something you wanted to do when the program has |
… | |
… | |
1304 | <dd> |
1526 | <dd> |
1305 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
1527 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
1306 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
1528 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
1307 | apropriate way for embedded loops.</p> |
1529 | apropriate way for embedded loops.</p> |
1308 | </dd> |
1530 | </dd> |
|
|
1531 | <dt>struct ev_loop *loop [read-only]</dt> |
|
|
1532 | <dd> |
|
|
1533 | <p>The embedded event loop.</p> |
|
|
1534 | </dd> |
1309 | </dl> |
1535 | </dl> |
1310 | |
1536 | |
1311 | |
1537 | |
1312 | |
1538 | |
1313 | |
1539 | |
1314 | |
1540 | |
1315 | </div> |
1541 | </div> |
1316 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1542 | <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> |
|
|
1543 | <div id="code_ev_fork_code_the_audacity_to_re-2"> |
|
|
1544 | <p>Fork watchers are called when a <code>fork ()</code> was detected (usually because |
|
|
1545 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1546 | <code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the |
|
|
1547 | event loop blocks next and before <code>ev_check</code> watchers are being called, |
|
|
1548 | and only in the child after the fork. If whoever good citizen calling |
|
|
1549 | <code>ev_default_fork</code> cheats and calls it in the wrong process, the fork |
|
|
1550 | handlers will be invoked, too, of course.</p> |
|
|
1551 | <dl> |
|
|
1552 | <dt>ev_fork_init (ev_signal *, callback)</dt> |
|
|
1553 | <dd> |
|
|
1554 | <p>Initialises and configures the fork watcher - it has no parameters of any |
|
|
1555 | kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless, |
|
|
1556 | believe me.</p> |
|
|
1557 | </dd> |
|
|
1558 | </dl> |
|
|
1559 | |
|
|
1560 | |
|
|
1561 | |
|
|
1562 | |
|
|
1563 | |
|
|
1564 | </div> |
|
|
1565 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1> |
1317 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1566 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1318 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1567 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1319 | <dl> |
1568 | <dl> |
1320 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1569 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1321 | <dd> |
1570 | <dd> |
… | |
… | |
1368 | |
1617 | |
1369 | |
1618 | |
1370 | |
1619 | |
1371 | |
1620 | |
1372 | </div> |
1621 | </div> |
1373 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1622 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1> |
1374 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1623 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1375 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1624 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1376 | emulate the internals of libevent, so here are some usage hints:</p> |
1625 | emulate the internals of libevent, so here are some usage hints:</p> |
1377 | <dl> |
1626 | <dl> |
1378 | <dt>* Use it by including <event.h>, as usual.</dt> |
1627 | <dt>* Use it by including <event.h>, as usual.</dt> |
… | |
… | |
1388 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1637 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1389 | to use the libev header file and library.</dt> |
1638 | to use the libev header file and library.</dt> |
1390 | </dl> |
1639 | </dl> |
1391 | |
1640 | |
1392 | </div> |
1641 | </div> |
1393 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1642 | <h1 id="C_SUPPORT">C++ SUPPORT</h1> |
1394 | <div id="C_SUPPORT_CONTENT"> |
1643 | <div id="C_SUPPORT_CONTENT"> |
1395 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1644 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1396 | you to use some convinience methods to start/stop watchers and also change |
1645 | you to use some convinience methods to start/stop watchers and also change |
1397 | the callback model to a model using method callbacks on objects.</p> |
1646 | the callback model to a model using method callbacks on objects.</p> |
1398 | <p>To use it,</p> |
1647 | <p>To use it,</p> |
… | |
… | |
1462 | </dd> |
1711 | </dd> |
1463 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
1712 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
1464 | <dd> |
1713 | <dd> |
1465 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
1714 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
1466 | </dd> |
1715 | </dd> |
|
|
1716 | <dt>w->update () <code>ev::stat</code> only</dt> |
|
|
1717 | <dd> |
|
|
1718 | <p>Invokes <code>ev_stat_stat</code>.</p> |
|
|
1719 | </dd> |
1467 | </dl> |
1720 | </dl> |
1468 | </p> |
1721 | </p> |
1469 | </dd> |
1722 | </dd> |
1470 | </dl> |
1723 | </dl> |
1471 | <p>Example: Define a class with an IO and idle watcher, start one of them in |
1724 | <p>Example: Define a class with an IO and idle watcher, start one of them in |
… | |
… | |
1483 | idle (this, &myclass::idle_cb) |
1736 | idle (this, &myclass::idle_cb) |
1484 | { |
1737 | { |
1485 | io.start (fd, ev::READ); |
1738 | io.start (fd, ev::READ); |
1486 | } |
1739 | } |
1487 | |
1740 | |
1488 | </pre> |
|
|
1489 | |
1741 | |
|
|
1742 | |
|
|
1743 | |
|
|
1744 | </pre> |
|
|
1745 | |
1490 | </div> |
1746 | </div> |
1491 | <h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1747 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
|
|
1748 | <div id="MACRO_MAGIC_CONTENT"> |
|
|
1749 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1750 | <code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and |
|
|
1751 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
|
|
1752 | <p>To make it easier to write programs that cope with either variant, the |
|
|
1753 | following macros are defined:</p> |
|
|
1754 | <dl> |
|
|
1755 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
|
|
1756 | <dd> |
|
|
1757 | <p>This provides the loop <i>argument</i> for functions, if one is required ("ev |
|
|
1758 | loop argument"). The <code>EV_A</code> form is used when this is the sole argument, |
|
|
1759 | <code>EV_A_</code> is used when other arguments are following. Example:</p> |
|
|
1760 | <pre> ev_unref (EV_A); |
|
|
1761 | ev_timer_add (EV_A_ watcher); |
|
|
1762 | ev_loop (EV_A_ 0); |
|
|
1763 | |
|
|
1764 | </pre> |
|
|
1765 | <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope, |
|
|
1766 | which is often provided by the following macro.</p> |
|
|
1767 | </dd> |
|
|
1768 | <dt><code>EV_P</code>, <code>EV_P_</code></dt> |
|
|
1769 | <dd> |
|
|
1770 | <p>This provides the loop <i>parameter</i> for functions, if one is required ("ev |
|
|
1771 | loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter, |
|
|
1772 | <code>EV_P_</code> is used when other parameters are following. Example:</p> |
|
|
1773 | <pre> // this is how ev_unref is being declared |
|
|
1774 | static void ev_unref (EV_P); |
|
|
1775 | |
|
|
1776 | // this is how you can declare your typical callback |
|
|
1777 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1778 | |
|
|
1779 | </pre> |
|
|
1780 | <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite |
|
|
1781 | suitable for use with <code>EV_A</code>.</p> |
|
|
1782 | </dd> |
|
|
1783 | <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt> |
|
|
1784 | <dd> |
|
|
1785 | <p>Similar to the other two macros, this gives you the value of the default |
|
|
1786 | loop, if multiple loops are supported ("ev loop default").</p> |
|
|
1787 | </dd> |
|
|
1788 | </dl> |
|
|
1789 | <p>Example: Declare and initialise a check watcher, working regardless of |
|
|
1790 | wether multiple loops are supported or not.</p> |
|
|
1791 | <pre> static void |
|
|
1792 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1793 | { |
|
|
1794 | ev_check_stop (EV_A_ w); |
|
|
1795 | } |
|
|
1796 | |
|
|
1797 | ev_check check; |
|
|
1798 | ev_check_init (&check, check_cb); |
|
|
1799 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1800 | ev_loop (EV_DEFAULT_ 0); |
|
|
1801 | |
|
|
1802 | |
|
|
1803 | |
|
|
1804 | |
|
|
1805 | </pre> |
|
|
1806 | |
|
|
1807 | </div> |
|
|
1808 | <h1 id="EMBEDDING">EMBEDDING</h1> |
1492 | <div id="EMBEDDING_CONTENT"> |
1809 | <div id="EMBEDDING_CONTENT"> |
1493 | <p>Libev can (and often is) directly embedded into host |
1810 | <p>Libev can (and often is) directly embedded into host |
1494 | applications. Examples of applications that embed it include the Deliantra |
1811 | applications. Examples of applications that embed it include the Deliantra |
1495 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1812 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1496 | and rxvt-unicode.</p> |
1813 | and rxvt-unicode.</p> |
… | |
… | |
1702 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
2019 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
1703 | additional independent event loops. Otherwise there will be no support |
2020 | additional independent event loops. Otherwise there will be no support |
1704 | for multiple event loops and there is no first event loop pointer |
2021 | for multiple event loops and there is no first event loop pointer |
1705 | argument. Instead, all functions act on the single default loop.</p> |
2022 | argument. Instead, all functions act on the single default loop.</p> |
1706 | </dd> |
2023 | </dd> |
1707 | <dt>EV_PERIODICS</dt> |
2024 | <dt>EV_PERIODIC_ENABLE</dt> |
1708 | <dd> |
2025 | <dd> |
1709 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported, |
2026 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
1710 | otherwise not. This saves a few kb of code.</p> |
2027 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2028 | code.</p> |
|
|
2029 | </dd> |
|
|
2030 | <dt>EV_EMBED_ENABLE</dt> |
|
|
2031 | <dd> |
|
|
2032 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
|
|
2033 | defined to be <code>0</code>, then they are not.</p> |
|
|
2034 | </dd> |
|
|
2035 | <dt>EV_STAT_ENABLE</dt> |
|
|
2036 | <dd> |
|
|
2037 | <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If |
|
|
2038 | defined to be <code>0</code>, then they are not.</p> |
|
|
2039 | </dd> |
|
|
2040 | <dt>EV_FORK_ENABLE</dt> |
|
|
2041 | <dd> |
|
|
2042 | <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If |
|
|
2043 | defined to be <code>0</code>, then they are not.</p> |
|
|
2044 | </dd> |
|
|
2045 | <dt>EV_MINIMAL</dt> |
|
|
2046 | <dd> |
|
|
2047 | <p>If you need to shave off some kilobytes of code at the expense of some |
|
|
2048 | speed, define this symbol to <code>1</code>. Currently only used for gcc to override |
|
|
2049 | some inlining decisions, saves roughly 30% codesize of amd64.</p> |
|
|
2050 | </dd> |
|
|
2051 | <dt>EV_PID_HASHSIZE</dt> |
|
|
2052 | <dd> |
|
|
2053 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
|
|
2054 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
|
|
2055 | than enough. If you need to manage thousands of children you might want to |
|
|
2056 | increase this value.</p> |
1711 | </dd> |
2057 | </dd> |
1712 | <dt>EV_COMMON</dt> |
2058 | <dt>EV_COMMON</dt> |
1713 | <dd> |
2059 | <dd> |
1714 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2060 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
1715 | this macro to a something else you can include more and other types of |
2061 | this macro to a something else you can include more and other types of |
… | |
… | |
1761 | |
2107 | |
1762 | |
2108 | |
1763 | </pre> |
2109 | </pre> |
1764 | |
2110 | |
1765 | </div> |
2111 | </div> |
1766 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2112 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
1767 | <div id="COMPLEXITIES_CONTENT"> |
2113 | <div id="COMPLEXITIES_CONTENT"> |
1768 | <p>In this section the complexities of (many of) the algorithms used inside |
2114 | <p>In this section the complexities of (many of) the algorithms used inside |
1769 | libev will be explained. For complexity discussions about backends see the |
2115 | libev will be explained. For complexity discussions about backends see the |
1770 | documentation for <code>ev_default_init</code>.</p> |
2116 | documentation for <code>ev_default_init</code>.</p> |
1771 | <p> |
2117 | <p> |
… | |
… | |
1784 | |
2130 | |
1785 | |
2131 | |
1786 | |
2132 | |
1787 | |
2133 | |
1788 | </div> |
2134 | </div> |
1789 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2135 | <h1 id="AUTHOR">AUTHOR</h1> |
1790 | <div id="AUTHOR_CONTENT"> |
2136 | <div id="AUTHOR_CONTENT"> |
1791 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2137 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1792 | |
2138 | |
1793 | </div> |
2139 | </div> |
1794 | </div></body> |
2140 | </div></body> |