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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" /> |
7 | <meta name="inputfile" content="<standard input>" /> |
7 | <meta name="inputfile" content="<standard input>" /> |
8 | <meta name="outputfile" content="<standard output>" /> |
8 | <meta name="outputfile" content="<standard output>" /> |
9 | <meta name="created" content="Tue Nov 27 11:59:06 2007" /> |
9 | <meta name="created" content="Fri Dec 7 17:49:47 2007" /> |
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11 | <link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> |
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> |
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59 | <li><a href="#AUTHOR">AUTHOR</a> |
60 | <li><a href="#AUTHOR">AUTHOR</a> |
60 | </li> |
61 | </li> |
61 | </ul><hr /> |
62 | </ul><hr /> |
62 | <!-- INDEX END --> |
63 | <!-- INDEX END --> |
63 | |
64 | |
64 | <h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> |
65 | <h1 id="NAME">NAME</h1> |
65 | <div id="NAME_CONTENT"> |
66 | <div id="NAME_CONTENT"> |
66 | <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> |
67 | |
68 | |
68 | </div> |
69 | </div> |
69 | <h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
70 | <h1 id="SYNOPSIS">SYNOPSIS</h1> |
70 | <div id="SYNOPSIS_CONTENT"> |
71 | <div id="SYNOPSIS_CONTENT"> |
71 | <pre> #include <ev.h> |
72 | <pre> #include <ev.h> |
72 | |
73 | |
73 | </pre> |
74 | </pre> |
74 | |
75 | |
75 | </div> |
76 | </div> |
76 | <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> |
77 | <div id="DESCRIPTION_CONTENT"> |
123 | <div id="DESCRIPTION_CONTENT"> |
78 | <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 |
79 | 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 |
80 | these event sources and provide your program with events.</p> |
126 | these event sources and provide your program with events.</p> |
81 | <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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85 | 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 |
86 | 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 |
87 | watcher.</p> |
133 | watcher.</p> |
88 | |
134 | |
89 | </div> |
135 | </div> |
90 | <h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
136 | <h1 id="FEATURES">FEATURES</h1> |
91 | <div id="FEATURES_CONTENT"> |
137 | <div id="FEATURES_CONTENT"> |
92 | <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 |
93 | kqueue mechanisms for file descriptor events, relative timers, absolute |
139 | BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms |
94 | timers with customised rescheduling, signal events, process status change |
140 | for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface |
95 | events (related to SIGCHLD), and event watchers dealing with the event |
141 | (for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers |
96 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
142 | with customised rescheduling (<code>ev_periodic</code>), synchronous signals |
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143 | (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event |
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144 | watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
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145 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
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146 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
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147 | (<code>ev_fork</code>).</p> |
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148 | <p>It also is quite fast (see this |
97 | fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing |
149 | <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent |
98 | it to libevent for example).</p> |
150 | for example).</p> |
99 | |
151 | |
100 | </div> |
152 | </div> |
101 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
153 | <h1 id="CONVENTIONS">CONVENTIONS</h1> |
102 | <div id="CONVENTIONS_CONTENT"> |
154 | <div id="CONVENTIONS_CONTENT"> |
103 | <p>Libev is very configurable. In this manual the default configuration |
155 | <p>Libev is very configurable. In this manual the default configuration will |
104 | will be described, which supports multiple event loops. For more info |
156 | be described, which supports multiple event loops. For more info about |
105 | about various configuration options please have a look at the file |
157 | various configuration options please have a look at <strong>EMBED</strong> section in |
106 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
158 | this manual. If libev was configured without support for multiple event |
107 | support for multiple event loops, then all functions taking an initial |
159 | loops, then all functions taking an initial argument of name <code>loop</code> |
108 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
160 | (which is always of type <code>struct ev_loop *</code>) will not have this argument.</p> |
109 | will not have this argument.</p> |
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110 | |
161 | |
111 | </div> |
162 | </div> |
112 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
163 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1> |
113 | <div id="TIME_REPRESENTATION_CONTENT"> |
164 | <div id="TIME_REPRESENTATION_CONTENT"> |
114 | <p>Libev represents time as a single floating point number, representing the |
165 | <p>Libev represents time as a single floating point number, representing the |
115 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
166 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
116 | the beginning of 1970, details are complicated, don't ask). This type is |
167 | the beginning of 1970, details are complicated, don't ask). This type is |
117 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
168 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
118 | to the <code>double</code> type in C, and when you need to do any calculations on |
169 | to the <code>double</code> type in C, and when you need to do any calculations on |
119 | it, you should treat it as such.</p> |
170 | it, you should treat it as such.</p> |
120 | |
171 | |
121 | </div> |
172 | </div> |
122 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
173 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1> |
123 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
174 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
124 | <p>These functions can be called anytime, even before initialising the |
175 | <p>These functions can be called anytime, even before initialising the |
125 | library in any way.</p> |
176 | library in any way.</p> |
126 | <dl> |
177 | <dl> |
127 | <dt>ev_tstamp ev_time ()</dt> |
178 | <dt>ev_tstamp ev_time ()</dt> |
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140 | version of the library your program was compiled against.</p> |
191 | 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, |
192 | <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 |
193 | as this indicates an incompatible change. Minor versions are usually |
143 | compatible to older versions, so a larger minor version alone is usually |
194 | compatible to older versions, so a larger minor version alone is usually |
144 | not a problem.</p> |
195 | not a problem.</p> |
145 | <p>Example: make sure we haven't accidentally been linked against the wrong |
196 | <p>Example: Make sure we haven't accidentally been linked against the wrong |
146 | version:</p> |
197 | version.</p> |
147 | <pre> assert (("libev version mismatch", |
198 | <pre> assert (("libev version mismatch", |
148 | ev_version_major () == EV_VERSION_MAJOR |
199 | ev_version_major () == EV_VERSION_MAJOR |
149 | && ev_version_minor () >= EV_VERSION_MINOR)); |
200 | && ev_version_minor () >= EV_VERSION_MINOR)); |
150 | |
201 | |
151 | </pre> |
202 | </pre> |
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181 | recommended ones.</p> |
232 | recommended ones.</p> |
182 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
233 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
183 | </dd> |
234 | </dd> |
184 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
235 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
185 | <dd> |
236 | <dd> |
186 | <p>Sets the allocation function to use (the prototype is similar to the |
237 | <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 |
238 | 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 |
239 | 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 |
240 | memory needs to be allocated, the library might abort or take some |
190 | destructive action. The default is your system realloc function.</p> |
241 | potentially destructive action. The default is your system realloc |
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242 | function.</p> |
191 | <p>You could override this function in high-availability programs to, say, |
243 | <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, |
244 | 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> |
245 | 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 |
246 | <p>Example: Replace the libev allocator with one that waits a bit and then |
195 | retries: better than mine).</p> |
247 | retries).</p> |
196 | <pre> static void * |
248 | <pre> static void * |
197 | persistent_realloc (void *ptr, long size) |
249 | persistent_realloc (void *ptr, size_t size) |
198 | { |
250 | { |
199 | for (;;) |
251 | for (;;) |
200 | { |
252 | { |
201 | void *newptr = realloc (ptr, size); |
253 | void *newptr = realloc (ptr, size); |
202 | |
254 | |
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219 | indicating the system call or subsystem causing the problem. If this |
271 | 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 |
272 | 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 |
273 | 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 |
274 | requested operation, or, if the condition doesn't go away, do bad stuff |
223 | (such as abort).</p> |
275 | (such as abort).</p> |
224 | <p>Example: do the same thing as libev does internally:</p> |
276 | <p>Example: This is basically the same thing that libev does internally, too.</p> |
225 | <pre> static void |
277 | <pre> static void |
226 | fatal_error (const char *msg) |
278 | fatal_error (const char *msg) |
227 | { |
279 | { |
228 | perror (msg); |
280 | perror (msg); |
229 | abort (); |
281 | abort (); |
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235 | </pre> |
287 | </pre> |
236 | </dd> |
288 | </dd> |
237 | </dl> |
289 | </dl> |
238 | |
290 | |
239 | </div> |
291 | </div> |
240 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
292 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1> |
241 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
293 | <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 |
294 | <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 |
295 | types of such loops, the <i>default</i> loop, which supports signals and child |
244 | events, and dynamically created loops which do not.</p> |
296 | 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 |
297 | <p>If you use threads, a common model is to run the default event loop |
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273 | or setgid) then libev will <i>not</i> look at the environment variable |
325 | or setgid) then libev will <i>not</i> look at the environment variable |
274 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
326 | <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 |
327 | 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 |
328 | useful to try out specific backends to test their performance, or to work |
277 | around bugs.</p> |
329 | around bugs.</p> |
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330 | </dd> |
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331 | <dt><code>EVFLAG_FORKCHECK</code></dt> |
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332 | <dd> |
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333 | <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after |
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334 | a fork, you can also make libev check for a fork in each iteration by |
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335 | enabling this flag.</p> |
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336 | <p>This works by calling <code>getpid ()</code> on every iteration of the loop, |
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337 | and thus this might slow down your event loop if you do a lot of loop |
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338 | iterations and little real work, but is usually not noticeable (on my |
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339 | Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence |
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340 | without a syscall and thus <i>very</i> fast, but my Linux system also has |
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341 | <code>pthread_atfork</code> which is even faster).</p> |
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342 | <p>The big advantage of this flag is that you can forget about fork (and |
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343 | forget about forgetting to tell libev about forking) when you use this |
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344 | flag.</p> |
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345 | <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code> |
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346 | environment variable.</p> |
278 | </dd> |
347 | </dd> |
279 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
348 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
280 | <dd> |
349 | <dd> |
281 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
350 | <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, |
351 | libev tries to roll its own fd_set with no limits on the number of fds, |
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365 | <dd> |
434 | <dd> |
366 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
435 | <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 |
436 | 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 |
437 | 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> |
438 | 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> |
439 | <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); |
440 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
372 | if (!epoller) |
441 | if (!epoller) |
373 | fatal ("no epoll found here, maybe it hides under your chair"); |
442 | fatal ("no epoll found here, maybe it hides under your chair"); |
374 | |
443 | |
375 | </pre> |
444 | </pre> |
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411 | <dt>ev_loop_fork (loop)</dt> |
480 | <dt>ev_loop_fork (loop)</dt> |
412 | <dd> |
481 | <dd> |
413 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
482 | <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 |
483 | <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> |
484 | after fork, and how you do this is entirely your own problem.</p> |
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485 | </dd> |
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486 | <dt>unsigned int ev_loop_count (loop)</dt> |
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487 | <dd> |
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488 | <p>Returns the count of loop iterations for the loop, which is identical to |
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489 | the number of times libev did poll for new events. It starts at <code>0</code> and |
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490 | happily wraps around with enough iterations.</p> |
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491 | <p>This value can sometimes be useful as a generation counter of sorts (it |
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492 | "ticks" the number of loop iterations), as it roughly corresponds with |
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493 | <code>ev_prepare</code> and <code>ev_check</code> calls.</p> |
416 | </dd> |
494 | </dd> |
417 | <dt>unsigned int ev_backend (loop)</dt> |
495 | <dt>unsigned int ev_backend (loop)</dt> |
418 | <dd> |
496 | <dd> |
419 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
497 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
420 | use.</p> |
498 | use.</p> |
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468 | be handled here by queueing them when their watcher gets executed. |
546 | be handled here by queueing them when their watcher gets executed. |
469 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
547 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
470 | were used, return, otherwise continue with step *. |
548 | were used, return, otherwise continue with step *. |
471 | |
549 | |
472 | </pre> |
550 | </pre> |
473 | <p>Example: queue some jobs and then loop until no events are outsanding |
551 | <p>Example: Queue some jobs and then loop until no events are outsanding |
474 | anymore.</p> |
552 | anymore.</p> |
475 | <pre> ... queue jobs here, make sure they register event watchers as long |
553 | <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..) |
554 | ... as they still have work to do (even an idle watcher will do..) |
477 | ev_loop (my_loop, 0); |
555 | ev_loop (my_loop, 0); |
478 | ... jobs done. yeah! |
556 | ... jobs done. yeah! |
… | |
… | |
497 | example, libev itself uses this for its internal signal pipe: It is not |
575 | 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 |
576 | 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 |
577 | 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 |
578 | 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> |
579 | 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> |
580 | <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code> |
503 | running when nothing else is active.</p> |
581 | running when nothing else is active.</p> |
504 | <pre> struct dv_signal exitsig; |
582 | <pre> struct ev_signal exitsig; |
505 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
583 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
506 | ev_signal_start (myloop, &exitsig); |
584 | ev_signal_start (loop, &exitsig); |
507 | evf_unref (myloop); |
585 | evf_unref (loop); |
508 | |
586 | |
509 | </pre> |
587 | </pre> |
510 | <p>Example: for some weird reason, unregister the above signal handler again.</p> |
588 | <p>Example: For some weird reason, unregister the above signal handler again.</p> |
511 | <pre> ev_ref (myloop); |
589 | <pre> ev_ref (loop); |
512 | ev_signal_stop (myloop, &exitsig); |
590 | ev_signal_stop (loop, &exitsig); |
513 | |
591 | |
514 | </pre> |
592 | </pre> |
515 | </dd> |
593 | </dd> |
516 | </dl> |
594 | </dl> |
517 | |
595 | |
518 | |
596 | |
519 | |
597 | |
520 | |
598 | |
521 | |
599 | |
522 | </div> |
600 | </div> |
523 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
601 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1> |
524 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
602 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
525 | <p>A watcher is a structure that you create and register to record your |
603 | <p>A watcher is a structure that you create and register to record your |
526 | interest in some event. For instance, if you want to wait for STDIN to |
604 | interest in some event. For instance, if you want to wait for STDIN to |
527 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
605 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
528 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
606 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
691 | events but its callback has not yet been invoked). As long as a watcher |
769 | events but its callback has not yet been invoked). As long as a watcher |
692 | is pending (but not active) you must not call an init function on it (but |
770 | is pending (but not active) you must not call an init function on it (but |
693 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
771 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
694 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
772 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
695 | </dd> |
773 | </dd> |
696 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
774 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
697 | <dd> |
775 | <dd> |
698 | <p>Returns the callback currently set on the watcher.</p> |
776 | <p>Returns the callback currently set on the watcher.</p> |
699 | </dd> |
777 | </dd> |
700 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
778 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
701 | <dd> |
779 | <dd> |
702 | <p>Change the callback. You can change the callback at virtually any time |
780 | <p>Change the callback. You can change the callback at virtually any time |
703 | (modulo threads).</p> |
781 | (modulo threads).</p> |
|
|
782 | </dd> |
|
|
783 | <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt> |
|
|
784 | <dt>int ev_priority (ev_TYPE *watcher)</dt> |
|
|
785 | <dd> |
|
|
786 | <p>Set and query the priority of the watcher. The priority is a small |
|
|
787 | integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code> |
|
|
788 | (default: <code>-2</code>). Pending watchers with higher priority will be invoked |
|
|
789 | before watchers with lower priority, but priority will not keep watchers |
|
|
790 | from being executed (except for <code>ev_idle</code> watchers).</p> |
|
|
791 | <p>This means that priorities are <i>only</i> used for ordering callback |
|
|
792 | invocation after new events have been received. This is useful, for |
|
|
793 | example, to reduce latency after idling, or more often, to bind two |
|
|
794 | watchers on the same event and make sure one is called first.</p> |
|
|
795 | <p>If you need to suppress invocation when higher priority events are pending |
|
|
796 | you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p> |
|
|
797 | <p>The default priority used by watchers when no priority has been set is |
|
|
798 | always <code>0</code>, which is supposed to not be too high and not be too low :).</p> |
|
|
799 | <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is |
|
|
800 | fine, as long as you do not mind that the priority value you query might |
|
|
801 | or might not have been adjusted to be within valid range.</p> |
704 | </dd> |
802 | </dd> |
705 | </dl> |
803 | </dl> |
706 | |
804 | |
707 | |
805 | |
708 | |
806 | |
… | |
… | |
733 | struct my_io *w = (struct my_io *)w_; |
831 | struct my_io *w = (struct my_io *)w_; |
734 | ... |
832 | ... |
735 | } |
833 | } |
736 | |
834 | |
737 | </pre> |
835 | </pre> |
738 | <p>More interesting and less C-conformant ways of catsing your callback type |
836 | <p>More interesting and less C-conformant ways of casting your callback type |
739 | have been omitted....</p> |
837 | instead have been omitted.</p> |
|
|
838 | <p>Another common scenario is having some data structure with multiple |
|
|
839 | watchers:</p> |
|
|
840 | <pre> struct my_biggy |
|
|
841 | { |
|
|
842 | int some_data; |
|
|
843 | ev_timer t1; |
|
|
844 | ev_timer t2; |
|
|
845 | } |
740 | |
846 | |
|
|
847 | </pre> |
|
|
848 | <p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated, |
|
|
849 | you need to use <code>offsetof</code>:</p> |
|
|
850 | <pre> #include <stddef.h> |
741 | |
851 | |
|
|
852 | static void |
|
|
853 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
854 | { |
|
|
855 | struct my_biggy big = (struct my_biggy * |
|
|
856 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
857 | } |
742 | |
858 | |
|
|
859 | static void |
|
|
860 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
861 | { |
|
|
862 | struct my_biggy big = (struct my_biggy * |
|
|
863 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
864 | } |
743 | |
865 | |
744 | |
866 | |
|
|
867 | |
|
|
868 | |
|
|
869 | </pre> |
|
|
870 | |
745 | </div> |
871 | </div> |
746 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
872 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
747 | <div id="WATCHER_TYPES_CONTENT"> |
873 | <div id="WATCHER_TYPES_CONTENT"> |
748 | <p>This section describes each watcher in detail, but will not repeat |
874 | <p>This section describes each watcher in detail, but will not repeat |
749 | information given in the last section. Any initialisation/set macros, |
875 | information given in the last section. Any initialisation/set macros, |
750 | functions and members specific to the watcher type are explained.</p> |
876 | functions and members specific to the watcher type are explained.</p> |
751 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
877 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
… | |
… | |
811 | <dt>int events [read-only]</dt> |
937 | <dt>int events [read-only]</dt> |
812 | <dd> |
938 | <dd> |
813 | <p>The events being watched.</p> |
939 | <p>The events being watched.</p> |
814 | </dd> |
940 | </dd> |
815 | </dl> |
941 | </dl> |
816 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
942 | <p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
817 | readable, but only once. Since it is likely line-buffered, you could |
943 | readable, but only once. Since it is likely line-buffered, you could |
818 | attempt to read a whole line in the callback:</p> |
944 | attempt to read a whole line in the callback.</p> |
819 | <pre> static void |
945 | <pre> static void |
820 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
946 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
821 | { |
947 | { |
822 | ev_io_stop (loop, w); |
948 | ev_io_stop (loop, w); |
823 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
949 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
… | |
… | |
872 | </dd> |
998 | </dd> |
873 | <dt>ev_timer_again (loop)</dt> |
999 | <dt>ev_timer_again (loop)</dt> |
874 | <dd> |
1000 | <dd> |
875 | <p>This will act as if the timer timed out and restart it again if it is |
1001 | <p>This will act as if the timer timed out and restart it again if it is |
876 | repeating. The exact semantics are:</p> |
1002 | repeating. The exact semantics are:</p> |
|
|
1003 | <p>If the timer is pending, its pending status is cleared.</p> |
877 | <p>If the timer is started but nonrepeating, stop it.</p> |
1004 | <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p> |
878 | <p>If the timer is repeating, either start it if necessary (with the repeat |
1005 | <p>If the timer is repeating, either start it if necessary (with the |
879 | value), or reset the running timer to the repeat value.</p> |
1006 | <code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p> |
880 | <p>This sounds a bit complicated, but here is a useful and typical |
1007 | <p>This sounds a bit complicated, but here is a useful and typical |
881 | example: Imagine you have a tcp connection and you want a so-called |
1008 | example: Imagine you have a tcp connection and you want a so-called idle |
882 | idle timeout, that is, you want to be called when there have been, |
1009 | timeout, that is, you want to be called when there have been, say, 60 |
883 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1010 | seconds of inactivity on the socket. The easiest way to do this is to |
884 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
1011 | configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call |
885 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
1012 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
886 | you go into an idle state where you do not expect data to travel on the |
1013 | you go into an idle state where you do not expect data to travel on the |
887 | socket, you can stop the timer, and again will automatically restart it if |
1014 | socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will |
888 | need be.</p> |
1015 | automatically restart it if need be.</p> |
889 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
1016 | <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code> |
890 | and only ever use the <code>repeat</code> value:</p> |
1017 | altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p> |
891 | <pre> ev_timer_init (timer, callback, 0., 5.); |
1018 | <pre> ev_timer_init (timer, callback, 0., 5.); |
892 | ev_timer_again (loop, timer); |
1019 | ev_timer_again (loop, timer); |
893 | ... |
1020 | ... |
894 | timer->again = 17.; |
1021 | timer->again = 17.; |
895 | ev_timer_again (loop, timer); |
1022 | ev_timer_again (loop, timer); |
896 | ... |
1023 | ... |
897 | timer->again = 10.; |
1024 | timer->again = 10.; |
898 | ev_timer_again (loop, timer); |
1025 | ev_timer_again (loop, timer); |
899 | |
1026 | |
900 | </pre> |
1027 | </pre> |
901 | <p>This is more efficient then stopping/starting the timer eahc time you want |
1028 | <p>This is more slightly efficient then stopping/starting the timer each time |
902 | to modify its timeout value.</p> |
1029 | you want to modify its timeout value.</p> |
903 | </dd> |
1030 | </dd> |
904 | <dt>ev_tstamp repeat [read-write]</dt> |
1031 | <dt>ev_tstamp repeat [read-write]</dt> |
905 | <dd> |
1032 | <dd> |
906 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
1033 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
907 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
1034 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
908 | which is also when any modifications are taken into account.</p> |
1035 | which is also when any modifications are taken into account.</p> |
909 | </dd> |
1036 | </dd> |
910 | </dl> |
1037 | </dl> |
911 | <p>Example: create a timer that fires after 60 seconds.</p> |
1038 | <p>Example: Create a timer that fires after 60 seconds.</p> |
912 | <pre> static void |
1039 | <pre> static void |
913 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1040 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
914 | { |
1041 | { |
915 | .. one minute over, w is actually stopped right here |
1042 | .. one minute over, w is actually stopped right here |
916 | } |
1043 | } |
… | |
… | |
918 | struct ev_timer mytimer; |
1045 | struct ev_timer mytimer; |
919 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1046 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
920 | ev_timer_start (loop, &mytimer); |
1047 | ev_timer_start (loop, &mytimer); |
921 | |
1048 | |
922 | </pre> |
1049 | </pre> |
923 | <p>Example: create a timeout timer that times out after 10 seconds of |
1050 | <p>Example: Create a timeout timer that times out after 10 seconds of |
924 | inactivity.</p> |
1051 | inactivity.</p> |
925 | <pre> static void |
1052 | <pre> static void |
926 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1053 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
927 | { |
1054 | { |
928 | .. ten seconds without any activity |
1055 | .. ten seconds without any activity |
… | |
… | |
1044 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
1171 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
1045 | switched off. Can be changed any time, but changes only take effect when |
1172 | switched off. Can be changed any time, but changes only take effect when |
1046 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
1173 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
1047 | </dd> |
1174 | </dd> |
1048 | </dl> |
1175 | </dl> |
1049 | <p>Example: call a callback every hour, or, more precisely, whenever the |
1176 | <p>Example: Call a callback every hour, or, more precisely, whenever the |
1050 | system clock is divisible by 3600. The callback invocation times have |
1177 | system clock is divisible by 3600. The callback invocation times have |
1051 | potentially a lot of jittering, but good long-term stability.</p> |
1178 | potentially a lot of jittering, but good long-term stability.</p> |
1052 | <pre> static void |
1179 | <pre> static void |
1053 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1180 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1054 | { |
1181 | { |
… | |
… | |
1058 | struct ev_periodic hourly_tick; |
1185 | struct ev_periodic hourly_tick; |
1059 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1186 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1060 | ev_periodic_start (loop, &hourly_tick); |
1187 | ev_periodic_start (loop, &hourly_tick); |
1061 | |
1188 | |
1062 | </pre> |
1189 | </pre> |
1063 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
1190 | <p>Example: The same as above, but use a reschedule callback to do it:</p> |
1064 | <pre> #include <math.h> |
1191 | <pre> #include <math.h> |
1065 | |
1192 | |
1066 | static ev_tstamp |
1193 | static ev_tstamp |
1067 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1194 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1068 | { |
1195 | { |
… | |
… | |
1070 | } |
1197 | } |
1071 | |
1198 | |
1072 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1199 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1073 | |
1200 | |
1074 | </pre> |
1201 | </pre> |
1075 | <p>Example: call a callback every hour, starting now:</p> |
1202 | <p>Example: Call a callback every hour, starting now:</p> |
1076 | <pre> struct ev_periodic hourly_tick; |
1203 | <pre> struct ev_periodic hourly_tick; |
1077 | ev_periodic_init (&hourly_tick, clock_cb, |
1204 | ev_periodic_init (&hourly_tick, clock_cb, |
1078 | fmod (ev_now (loop), 3600.), 3600., 0); |
1205 | fmod (ev_now (loop), 3600.), 3600., 0); |
1079 | ev_periodic_start (loop, &hourly_tick); |
1206 | ev_periodic_start (loop, &hourly_tick); |
1080 | |
1207 | |
… | |
… | |
1141 | <dd> |
1268 | <dd> |
1142 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
1269 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
1143 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
1270 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
1144 | </dd> |
1271 | </dd> |
1145 | </dl> |
1272 | </dl> |
1146 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
1273 | <p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p> |
1147 | <pre> static void |
1274 | <pre> static void |
1148 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1275 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1149 | { |
1276 | { |
1150 | ev_unloop (loop, EVUNLOOP_ALL); |
1277 | ev_unloop (loop, EVUNLOOP_ALL); |
1151 | } |
1278 | } |
… | |
… | |
1168 | <p>The path does not need to exist: changing from "path exists" to "path does |
1295 | <p>The path does not need to exist: changing from "path exists" to "path does |
1169 | not exist" is a status change like any other. The condition "path does |
1296 | not exist" is a status change like any other. The condition "path does |
1170 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1297 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
1171 | otherwise always forced to be at least one) and all the other fields of |
1298 | otherwise always forced to be at least one) and all the other fields of |
1172 | the stat buffer having unspecified contents.</p> |
1299 | the stat buffer having unspecified contents.</p> |
|
|
1300 | <p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is |
|
|
1301 | relative and your working directory changes, the behaviour is undefined.</p> |
1173 | <p>Since there is no standard to do this, the portable implementation simply |
1302 | <p>Since there is no standard to do this, the portable implementation simply |
1174 | calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You |
1303 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
1175 | can specify a recommended polling interval for this case. If you specify |
1304 | can specify a recommended polling interval for this case. If you specify |
1176 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1305 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
1177 | unspecified default</i> value will be used (which you can expect to be around |
1306 | unspecified default</i> value will be used (which you can expect to be around |
1178 | five seconds, although this might change dynamically). Libev will also |
1307 | five seconds, although this might change dynamically). Libev will also |
1179 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
1308 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
1180 | usually overkill.</p> |
1309 | usually overkill.</p> |
1181 | <p>This watcher type is not meant for massive numbers of stat watchers, |
1310 | <p>This watcher type is not meant for massive numbers of stat watchers, |
1182 | as even with OS-supported change notifications, this can be |
1311 | as even with OS-supported change notifications, this can be |
1183 | resource-intensive.</p> |
1312 | resource-intensive.</p> |
1184 | <p>At the time of this writing, no specific OS backends are implemented, but |
1313 | <p>At the time of this writing, only the Linux inotify interface is |
1185 | if demand increases, at least a kqueue and inotify backend will be added.</p> |
1314 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1315 | reader). Inotify will be used to give hints only and should not change the |
|
|
1316 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
|
|
1317 | to fall back to regular polling again even with inotify, but changes are |
|
|
1318 | usually detected immediately, and if the file exists there will be no |
|
|
1319 | polling.</p> |
1186 | <dl> |
1320 | <dl> |
1187 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1321 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
1188 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1322 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
1189 | <dd> |
1323 | <dd> |
1190 | <p>Configures the watcher to wait for status changes of the given |
1324 | <p>Configures the watcher to wait for status changes of the given |
… | |
… | |
1253 | </pre> |
1387 | </pre> |
1254 | |
1388 | |
1255 | </div> |
1389 | </div> |
1256 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1390 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
1257 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1391 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1258 | <p>Idle watchers trigger events when there are no other events are pending |
1392 | <p>Idle watchers trigger events when no other events of the same or higher |
1259 | (prepare, check and other idle watchers do not count). That is, as long |
1393 | priority are pending (prepare, check and other idle watchers do not |
1260 | as your process is busy handling sockets or timeouts (or even signals, |
1394 | count).</p> |
1261 | imagine) it will not be triggered. But when your process is idle all idle |
1395 | <p>That is, as long as your process is busy handling sockets or timeouts |
1262 | watchers are being called again and again, once per event loop iteration - |
1396 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1397 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1398 | are pending), the idle watchers are being called once per event loop |
1263 | until stopped, that is, or your process receives more events and becomes |
1399 | iteration - until stopped, that is, or your process receives more events |
1264 | busy.</p> |
1400 | and becomes busy again with higher priority stuff.</p> |
1265 | <p>The most noteworthy effect is that as long as any idle watchers are |
1401 | <p>The most noteworthy effect is that as long as any idle watchers are |
1266 | active, the process will not block when waiting for new events.</p> |
1402 | active, the process will not block when waiting for new events.</p> |
1267 | <p>Apart from keeping your process non-blocking (which is a useful |
1403 | <p>Apart from keeping your process non-blocking (which is a useful |
1268 | effect on its own sometimes), idle watchers are a good place to do |
1404 | effect on its own sometimes), idle watchers are a good place to do |
1269 | "pseudo-background processing", or delay processing stuff to after the |
1405 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
1274 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1410 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1275 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1411 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1276 | believe me.</p> |
1412 | believe me.</p> |
1277 | </dd> |
1413 | </dd> |
1278 | </dl> |
1414 | </dl> |
1279 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
1415 | <p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the |
1280 | callback, free it. Alos, use no error checking, as usual.</p> |
1416 | callback, free it. Also, use no error checking, as usual.</p> |
1281 | <pre> static void |
1417 | <pre> static void |
1282 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1418 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1283 | { |
1419 | { |
1284 | free (w); |
1420 | free (w); |
1285 | // now do something you wanted to do when the program has |
1421 | // now do something you wanted to do when the program has |
… | |
… | |
1359 | |
1495 | |
1360 | // create io watchers for each fd and a timer before blocking |
1496 | // create io watchers for each fd and a timer before blocking |
1361 | static void |
1497 | static void |
1362 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1498 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1363 | { |
1499 | { |
1364 | int timeout = 3600000;truct pollfd fds [nfd]; |
1500 | int timeout = 3600000; |
|
|
1501 | struct pollfd fds [nfd]; |
1365 | // actual code will need to loop here and realloc etc. |
1502 | // actual code will need to loop here and realloc etc. |
1366 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1503 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1367 | |
1504 | |
1368 | /* the callback is illegal, but won't be called as we stop during check */ |
1505 | /* the callback is illegal, but won't be called as we stop during check */ |
1369 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1506 | ev_timer_init (&tw, 0, timeout * 1e-3); |
… | |
… | |
1510 | |
1647 | |
1511 | |
1648 | |
1512 | |
1649 | |
1513 | |
1650 | |
1514 | </div> |
1651 | </div> |
1515 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1652 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1> |
1516 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1653 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1517 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1654 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1518 | <dl> |
1655 | <dl> |
1519 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1656 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1520 | <dd> |
1657 | <dd> |
… | |
… | |
1567 | |
1704 | |
1568 | |
1705 | |
1569 | |
1706 | |
1570 | |
1707 | |
1571 | </div> |
1708 | </div> |
1572 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1709 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1> |
1573 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1710 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1574 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1711 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1575 | emulate the internals of libevent, so here are some usage hints:</p> |
1712 | emulate the internals of libevent, so here are some usage hints:</p> |
1576 | <dl> |
1713 | <dl> |
1577 | <dt>* Use it by including <event.h>, as usual.</dt> |
1714 | <dt>* Use it by including <event.h>, as usual.</dt> |
… | |
… | |
1587 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1724 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1588 | to use the libev header file and library.</dt> |
1725 | to use the libev header file and library.</dt> |
1589 | </dl> |
1726 | </dl> |
1590 | |
1727 | |
1591 | </div> |
1728 | </div> |
1592 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1729 | <h1 id="C_SUPPORT">C++ SUPPORT</h1> |
1593 | <div id="C_SUPPORT_CONTENT"> |
1730 | <div id="C_SUPPORT_CONTENT"> |
1594 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1731 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
1595 | you to use some convinience methods to start/stop watchers and also change |
1732 | you to use some convinience methods to start/stop watchers and also change |
1596 | the callback model to a model using method callbacks on objects.</p> |
1733 | the callback model to a model using method callbacks on objects.</p> |
1597 | <p>To use it,</p> |
1734 | <p>To use it,</p> |
… | |
… | |
1692 | |
1829 | |
1693 | |
1830 | |
1694 | </pre> |
1831 | </pre> |
1695 | |
1832 | |
1696 | </div> |
1833 | </div> |
1697 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1834 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
1698 | <div id="MACRO_MAGIC_CONTENT"> |
1835 | <div id="MACRO_MAGIC_CONTENT"> |
1699 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1836 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
1700 | <code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and |
1837 | <code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and |
1701 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1838 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
1702 | <p>To make it easier to write programs that cope with either variant, the |
1839 | <p>To make it easier to write programs that cope with either variant, the |
… | |
… | |
1734 | <dd> |
1871 | <dd> |
1735 | <p>Similar to the other two macros, this gives you the value of the default |
1872 | <p>Similar to the other two macros, this gives you the value of the default |
1736 | loop, if multiple loops are supported ("ev loop default").</p> |
1873 | loop, if multiple loops are supported ("ev loop default").</p> |
1737 | </dd> |
1874 | </dd> |
1738 | </dl> |
1875 | </dl> |
1739 | <p>Example: Declare and initialise a check watcher, working regardless of |
1876 | <p>Example: Declare and initialise a check watcher, utilising the above |
1740 | wether multiple loops are supported or not.</p> |
1877 | macros so it will work regardless of wether multiple loops are supported |
|
|
1878 | or not.</p> |
1741 | <pre> static void |
1879 | <pre> static void |
1742 | check_cb (EV_P_ ev_timer *w, int revents) |
1880 | check_cb (EV_P_ ev_timer *w, int revents) |
1743 | { |
1881 | { |
1744 | ev_check_stop (EV_A_ w); |
1882 | ev_check_stop (EV_A_ w); |
1745 | } |
1883 | } |
… | |
… | |
1747 | ev_check check; |
1885 | ev_check check; |
1748 | ev_check_init (&check, check_cb); |
1886 | ev_check_init (&check, check_cb); |
1749 | ev_check_start (EV_DEFAULT_ &check); |
1887 | ev_check_start (EV_DEFAULT_ &check); |
1750 | ev_loop (EV_DEFAULT_ 0); |
1888 | ev_loop (EV_DEFAULT_ 0); |
1751 | |
1889 | |
1752 | |
|
|
1753 | |
|
|
1754 | |
|
|
1755 | </pre> |
1890 | </pre> |
1756 | |
1891 | |
1757 | </div> |
1892 | </div> |
1758 | <h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1893 | <h1 id="EMBEDDING">EMBEDDING</h1> |
1759 | <div id="EMBEDDING_CONTENT"> |
1894 | <div id="EMBEDDING_CONTENT"> |
1760 | <p>Libev can (and often is) directly embedded into host |
1895 | <p>Libev can (and often is) directly embedded into host |
1761 | applications. Examples of applications that embed it include the Deliantra |
1896 | applications. Examples of applications that embed it include the Deliantra |
1762 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1897 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1763 | and rxvt-unicode.</p> |
1898 | and rxvt-unicode.</p> |
… | |
… | |
1800 | ev_vars.h |
1935 | ev_vars.h |
1801 | ev_wrap.h |
1936 | ev_wrap.h |
1802 | |
1937 | |
1803 | ev_win32.c required on win32 platforms only |
1938 | ev_win32.c required on win32 platforms only |
1804 | |
1939 | |
1805 | ev_select.c only when select backend is enabled (which is by default) |
1940 | ev_select.c only when select backend is enabled (which is enabled by default) |
1806 | ev_poll.c only when poll backend is enabled (disabled by default) |
1941 | ev_poll.c only when poll backend is enabled (disabled by default) |
1807 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1942 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1808 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1943 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1809 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1944 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1810 | |
1945 | |
… | |
… | |
1937 | </dd> |
2072 | </dd> |
1938 | <dt>EV_USE_DEVPOLL</dt> |
2073 | <dt>EV_USE_DEVPOLL</dt> |
1939 | <dd> |
2074 | <dd> |
1940 | <p>reserved for future expansion, works like the USE symbols above.</p> |
2075 | <p>reserved for future expansion, works like the USE symbols above.</p> |
1941 | </dd> |
2076 | </dd> |
|
|
2077 | <dt>EV_USE_INOTIFY</dt> |
|
|
2078 | <dd> |
|
|
2079 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify |
|
|
2080 | interface to speed up <code>ev_stat</code> watchers. Its actual availability will |
|
|
2081 | be detected at runtime.</p> |
|
|
2082 | </dd> |
1942 | <dt>EV_H</dt> |
2083 | <dt>EV_H</dt> |
1943 | <dd> |
2084 | <dd> |
1944 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
2085 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
1945 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
2086 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
1946 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
2087 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
… | |
… | |
1975 | <dd> |
2116 | <dd> |
1976 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
2117 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
1977 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
2118 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
1978 | code.</p> |
2119 | code.</p> |
1979 | </dd> |
2120 | </dd> |
|
|
2121 | <dt>EV_IDLE_ENABLE</dt> |
|
|
2122 | <dd> |
|
|
2123 | <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If |
|
|
2124 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2125 | code.</p> |
|
|
2126 | </dd> |
1980 | <dt>EV_EMBED_ENABLE</dt> |
2127 | <dt>EV_EMBED_ENABLE</dt> |
1981 | <dd> |
2128 | <dd> |
1982 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
2129 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
1983 | defined to be <code>0</code>, then they are not.</p> |
2130 | defined to be <code>0</code>, then they are not.</p> |
1984 | </dd> |
2131 | </dd> |
… | |
… | |
1995 | <dt>EV_MINIMAL</dt> |
2142 | <dt>EV_MINIMAL</dt> |
1996 | <dd> |
2143 | <dd> |
1997 | <p>If you need to shave off some kilobytes of code at the expense of some |
2144 | <p>If you need to shave off some kilobytes of code at the expense of some |
1998 | speed, define this symbol to <code>1</code>. Currently only used for gcc to override |
2145 | speed, define this symbol to <code>1</code>. Currently only used for gcc to override |
1999 | some inlining decisions, saves roughly 30% codesize of amd64.</p> |
2146 | some inlining decisions, saves roughly 30% codesize of amd64.</p> |
|
|
2147 | </dd> |
|
|
2148 | <dt>EV_PID_HASHSIZE</dt> |
|
|
2149 | <dd> |
|
|
2150 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
|
|
2151 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
|
|
2152 | than enough. If you need to manage thousands of children you might want to |
|
|
2153 | increase this value (<i>must</i> be a power of two).</p> |
|
|
2154 | </dd> |
|
|
2155 | <dt>EV_INOTIFY_HASHSIZE</dt> |
|
|
2156 | <dd> |
|
|
2157 | <p><code>ev_staz</code> watchers use a small hash table to distribute workload by |
|
|
2158 | inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), |
|
|
2159 | usually more than enough. If you need to manage thousands of <code>ev_stat</code> |
|
|
2160 | watchers you might want to increase this value (<i>must</i> be a power of |
|
|
2161 | two).</p> |
2000 | </dd> |
2162 | </dd> |
2001 | <dt>EV_COMMON</dt> |
2163 | <dt>EV_COMMON</dt> |
2002 | <dd> |
2164 | <dd> |
2003 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2165 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
2004 | this macro to a something else you can include more and other types of |
2166 | this macro to a something else you can include more and other types of |
… | |
… | |
2031 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2193 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
2032 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2194 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
2033 | will be compiled. It is pretty complex because it provides its own header |
2195 | will be compiled. It is pretty complex because it provides its own header |
2034 | file.</p> |
2196 | file.</p> |
2035 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2197 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
2036 | that everybody includes and which overrides some autoconf choices:</p> |
2198 | that everybody includes and which overrides some configure choices:</p> |
|
|
2199 | <pre> #define EV_MINIMAL 1 |
2037 | <pre> #define EV_USE_POLL 0 |
2200 | #define EV_USE_POLL 0 |
2038 | #define EV_MULTIPLICITY 0 |
2201 | #define EV_MULTIPLICITY 0 |
2039 | #define EV_PERIODICS 0 |
2202 | #define EV_PERIODIC_ENABLE 0 |
|
|
2203 | #define EV_STAT_ENABLE 0 |
|
|
2204 | #define EV_FORK_ENABLE 0 |
2040 | #define EV_CONFIG_H <config.h> |
2205 | #define EV_CONFIG_H <config.h> |
|
|
2206 | #define EV_MINPRI 0 |
|
|
2207 | #define EV_MAXPRI 0 |
2041 | |
2208 | |
2042 | #include "ev++.h" |
2209 | #include "ev++.h" |
2043 | |
2210 | |
2044 | </pre> |
2211 | </pre> |
2045 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
2212 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
… | |
… | |
2050 | |
2217 | |
2051 | |
2218 | |
2052 | </pre> |
2219 | </pre> |
2053 | |
2220 | |
2054 | </div> |
2221 | </div> |
2055 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2222 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
2056 | <div id="COMPLEXITIES_CONTENT"> |
2223 | <div id="COMPLEXITIES_CONTENT"> |
2057 | <p>In this section the complexities of (many of) the algorithms used inside |
2224 | <p>In this section the complexities of (many of) the algorithms used inside |
2058 | libev will be explained. For complexity discussions about backends see the |
2225 | libev will be explained. For complexity discussions about backends see the |
2059 | documentation for <code>ev_default_init</code>.</p> |
2226 | documentation for <code>ev_default_init</code>.</p> |
2060 | <p> |
2227 | <p> |
2061 | <dl> |
2228 | <dl> |
2062 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2229 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
2063 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2230 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
2064 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2231 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
2065 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2232 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
2066 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> |
2233 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
2067 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2234 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
2068 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
2235 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
2069 | <dt>Activating one watcher: O(1)</dt> |
2236 | <dt>Activating one watcher: O(1)</dt> |
2070 | </dl> |
2237 | </dl> |
2071 | </p> |
2238 | </p> |
… | |
… | |
2073 | |
2240 | |
2074 | |
2241 | |
2075 | |
2242 | |
2076 | |
2243 | |
2077 | </div> |
2244 | </div> |
2078 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
2245 | <h1 id="AUTHOR">AUTHOR</h1> |
2079 | <div id="AUTHOR_CONTENT"> |
2246 | <div id="AUTHOR_CONTENT"> |
2080 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2247 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2081 | |
2248 | |
2082 | </div> |
2249 | </div> |
2083 | </div></body> |
2250 | </div></body> |