… | |
… | |
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="Fri Nov 23 17:17:04 2007" /> |
9 | <meta name="created" content="Wed Nov 28 12:27:27 2007" /> |
10 | <meta name="generator" content="Pod::Xhtml 1.57" /> |
10 | <meta name="generator" content="Pod::Xhtml 1.57" /> |
11 | <link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> |
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> |
|
|
19 | <li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
24 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
25 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
26 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
|
|
27 | <ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
28 | <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | </ul> |
29 | </ul> |
28 | </li> |
30 | </li> |
29 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
31 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> |
32 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
33 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> |
32 | <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> |
33 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
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> |
34 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
36 | <li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> |
|
|
37 | <li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li> |
35 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
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> |
36 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
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> |
|
|
40 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> |
|
|
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> |
37 | </ul> |
42 | </ul> |
38 | </li> |
43 | </li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
44 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
45 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
46 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
|
|
47 | <li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li> |
|
|
48 | <li><a href="#EMBEDDING">EMBEDDING</a> |
|
|
49 | <ul><li><a href="#FILESETS">FILESETS</a> |
|
|
50 | <ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li> |
|
|
51 | <li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> |
|
|
52 | <li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> |
|
|
53 | </ul> |
|
|
54 | </li> |
|
|
55 | <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> |
|
|
56 | <li><a href="#EXAMPLES">EXAMPLES</a></li> |
|
|
57 | </ul> |
|
|
58 | </li> |
|
|
59 | <li><a href="#COMPLEXITIES">COMPLEXITIES</a></li> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
60 | <li><a href="#AUTHOR">AUTHOR</a> |
43 | </li> |
61 | </li> |
44 | </ul><hr /> |
62 | </ul><hr /> |
45 | <!-- INDEX END --> |
63 | <!-- INDEX END --> |
46 | |
64 | |
47 | <h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> |
65 | <h1 id="NAME">NAME</h1> |
48 | <div id="NAME_CONTENT"> |
66 | <div id="NAME_CONTENT"> |
49 | <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> |
50 | |
68 | |
51 | </div> |
69 | </div> |
52 | <h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
70 | <h1 id="SYNOPSIS">SYNOPSIS</h1> |
53 | <div id="SYNOPSIS_CONTENT"> |
71 | <div id="SYNOPSIS_CONTENT"> |
54 | <pre> #include <ev.h> |
72 | <pre> #include <ev.h> |
55 | |
73 | |
56 | </pre> |
74 | </pre> |
57 | |
75 | |
58 | </div> |
76 | </div> |
59 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
77 | <h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1> |
|
|
78 | <div id="EXAMPLE_PROGRAM_CONTENT"> |
|
|
79 | <pre> #include <ev.h> |
|
|
80 | |
|
|
81 | ev_io stdin_watcher; |
|
|
82 | ev_timer timeout_watcher; |
|
|
83 | |
|
|
84 | /* called when data readable on stdin */ |
|
|
85 | static void |
|
|
86 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
|
|
87 | { |
|
|
88 | /* puts ("stdin ready"); */ |
|
|
89 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
|
|
90 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
|
|
91 | } |
|
|
92 | |
|
|
93 | static void |
|
|
94 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
95 | { |
|
|
96 | /* puts ("timeout"); */ |
|
|
97 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
|
|
98 | } |
|
|
99 | |
|
|
100 | int |
|
|
101 | main (void) |
|
|
102 | { |
|
|
103 | struct ev_loop *loop = ev_default_loop (0); |
|
|
104 | |
|
|
105 | /* initialise an io watcher, then start it */ |
|
|
106 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
|
|
107 | ev_io_start (loop, &stdin_watcher); |
|
|
108 | |
|
|
109 | /* simple non-repeating 5.5 second timeout */ |
|
|
110 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
111 | ev_timer_start (loop, &timeout_watcher); |
|
|
112 | |
|
|
113 | /* loop till timeout or data ready */ |
|
|
114 | ev_loop (loop, 0); |
|
|
115 | |
|
|
116 | return 0; |
|
|
117 | } |
|
|
118 | |
|
|
119 | </pre> |
|
|
120 | |
|
|
121 | </div> |
|
|
122 | <h1 id="DESCRIPTION">DESCRIPTION</h1> |
60 | <div id="DESCRIPTION_CONTENT"> |
123 | <div id="DESCRIPTION_CONTENT"> |
61 | <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 |
62 | 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 |
63 | these event sources and provide your program with events.</p> |
126 | these event sources and provide your program with events.</p> |
64 | <p>To do this, it must take more or less complete control over your process |
127 | <p>To do this, it must take more or less complete control over your process |
… | |
… | |
68 | 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 |
69 | 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 |
70 | watcher.</p> |
133 | watcher.</p> |
71 | |
134 | |
72 | </div> |
135 | </div> |
73 | <h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
136 | <h1 id="FEATURES">FEATURES</h1> |
74 | <div id="FEATURES_CONTENT"> |
137 | <div id="FEATURES_CONTENT"> |
75 | <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 |
76 | kqueue mechanisms for file descriptor events, relative timers, absolute |
139 | bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms |
77 | timers with customised rescheduling, signal events, process status change |
140 | for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>), |
78 | events (related to SIGCHLD), and event watchers dealing with the event |
141 | absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous |
79 | 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 |
|
|
143 | event watchers dealing with the event loop mechanism itself (<code>ev_idle</code>, |
|
|
144 | <code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as |
|
|
145 | file watchers (<code>ev_stat</code>) and even limited support for fork events |
|
|
146 | (<code>ev_fork</code>).</p> |
|
|
147 | <p>It also is quite fast (see this |
80 | 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 |
81 | it to libevent for example).</p> |
149 | for example).</p> |
82 | |
150 | |
83 | </div> |
151 | </div> |
84 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
152 | <h1 id="CONVENTIONS">CONVENTIONS</h1> |
85 | <div id="CONVENTIONS_CONTENT"> |
153 | <div id="CONVENTIONS_CONTENT"> |
86 | <p>Libev is very configurable. In this manual the default configuration |
154 | <p>Libev is very configurable. In this manual the default configuration will |
87 | will be described, which supports multiple event loops. For more info |
155 | be described, which supports multiple event loops. For more info about |
88 | 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 |
89 | <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 |
90 | 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> |
91 | 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> |
92 | will not have this argument.</p> |
|
|
93 | |
160 | |
94 | </div> |
161 | </div> |
95 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
162 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1> |
96 | <div id="TIME_REPRESENTATION_CONTENT"> |
163 | <div id="TIME_REPRESENTATION_CONTENT"> |
97 | <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 |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
165 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | 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 |
100 | 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 |
101 | 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 |
102 | it, you should treat it as such.</p> |
169 | it, you should treat it as such.</p> |
103 | |
170 | |
104 | |
|
|
105 | |
|
|
106 | |
|
|
107 | |
|
|
108 | </div> |
171 | </div> |
109 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
172 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1> |
110 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
173 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
111 | <p>These functions can be called anytime, even before initialising the |
174 | <p>These functions can be called anytime, even before initialising the |
112 | library in any way.</p> |
175 | library in any way.</p> |
113 | <dl> |
176 | <dl> |
114 | <dt>ev_tstamp ev_time ()</dt> |
177 | <dt>ev_tstamp ev_time ()</dt> |
… | |
… | |
127 | version of the library your program was compiled against.</p> |
190 | version of the library your program was compiled against.</p> |
128 | <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, |
129 | as this indicates an incompatible change. Minor versions are usually |
192 | as this indicates an incompatible change. Minor versions are usually |
130 | 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 |
131 | not a problem.</p> |
194 | not a problem.</p> |
132 | <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 |
133 | version:</p> |
196 | version.</p> |
134 | <pre> assert (("libev version mismatch", |
197 | <pre> assert (("libev version mismatch", |
135 | ev_version_major () == EV_VERSION_MAJOR |
198 | ev_version_major () == EV_VERSION_MAJOR |
136 | && ev_version_minor () >= EV_VERSION_MINOR)); |
199 | && ev_version_minor () >= EV_VERSION_MINOR)); |
137 | |
200 | |
138 | </pre> |
201 | </pre> |
… | |
… | |
157 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
220 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
158 | most BSDs and will not be autodetected unless you explicitly request it |
221 | most BSDs and will not be autodetected unless you explicitly request it |
159 | (assuming you know what you are doing). This is the set of backends that |
222 | (assuming you know what you are doing). This is the set of backends that |
160 | libev will probe for if you specify no backends explicitly.</p> |
223 | libev will probe for if you specify no backends explicitly.</p> |
161 | </dd> |
224 | </dd> |
|
|
225 | <dt>unsigned int ev_embeddable_backends ()</dt> |
|
|
226 | <dd> |
|
|
227 | <p>Returns the set of backends that are embeddable in other event loops. This |
|
|
228 | is the theoretical, all-platform, value. To find which backends |
|
|
229 | might be supported on the current system, you would need to look at |
|
|
230 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
|
|
231 | recommended ones.</p> |
|
|
232 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
|
|
233 | </dd> |
162 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
234 | <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt> |
163 | <dd> |
235 | <dd> |
164 | <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 |
165 | 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 |
166 | 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 |
167 | needs to be allocated, the library might abort or take some potentially |
239 | allocated, the library might abort or take some potentially destructive |
168 | destructive action. The default is your system realloc function.</p> |
240 | action. The default is your system realloc function.</p> |
169 | <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, |
170 | 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, |
171 | 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> |
172 | <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 |
173 | retries: better than mine).</p> |
245 | retries).</p> |
174 | <pre> static void * |
246 | <pre> static void * |
175 | persistent_realloc (void *ptr, long size) |
247 | persistent_realloc (void *ptr, size_t size) |
176 | { |
248 | { |
177 | for (;;) |
249 | for (;;) |
178 | { |
250 | { |
179 | void *newptr = realloc (ptr, size); |
251 | void *newptr = realloc (ptr, size); |
180 | |
252 | |
… | |
… | |
197 | indicating the system call or subsystem causing the problem. If this |
269 | indicating the system call or subsystem causing the problem. If this |
198 | 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 |
199 | 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 |
200 | 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 |
201 | (such as abort).</p> |
273 | (such as abort).</p> |
202 | <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> |
203 | <pre> static void |
275 | <pre> static void |
204 | fatal_error (const char *msg) |
276 | fatal_error (const char *msg) |
205 | { |
277 | { |
206 | perror (msg); |
278 | perror (msg); |
207 | abort (); |
279 | abort (); |
… | |
… | |
213 | </pre> |
285 | </pre> |
214 | </dd> |
286 | </dd> |
215 | </dl> |
287 | </dl> |
216 | |
288 | |
217 | </div> |
289 | </div> |
218 | <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> |
219 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
291 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
220 | <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 |
221 | 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 |
222 | events, and dynamically created loops which do not.</p> |
294 | events, and dynamically created loops which do not.</p> |
223 | <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 |
… | |
… | |
343 | <dd> |
415 | <dd> |
344 | <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 |
345 | 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 |
346 | 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 |
347 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
419 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
348 | <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> |
349 | <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); |
350 | if (!epoller) |
422 | if (!epoller) |
351 | fatal ("no epoll found here, maybe it hides under your chair"); |
423 | fatal ("no epoll found here, maybe it hides under your chair"); |
352 | |
424 | |
353 | </pre> |
425 | </pre> |
354 | </dd> |
426 | </dd> |
355 | <dt>ev_default_destroy ()</dt> |
427 | <dt>ev_default_destroy ()</dt> |
356 | <dd> |
428 | <dd> |
357 | <p>Destroys the default loop again (frees all memory and kernel state |
429 | <p>Destroys the default loop again (frees all memory and kernel state |
358 | etc.). This stops all registered event watchers (by not touching them in |
430 | etc.). None of the active event watchers will be stopped in the normal |
359 | any way whatsoever, although you cannot rely on this :).</p> |
431 | sense, so e.g. <code>ev_is_active</code> might still return true. It is your |
|
|
432 | responsibility to either stop all watchers cleanly yoursef <i>before</i> |
|
|
433 | calling this function, or cope with the fact afterwards (which is usually |
|
|
434 | the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them |
|
|
435 | for example).</p> |
360 | </dd> |
436 | </dd> |
361 | <dt>ev_loop_destroy (loop)</dt> |
437 | <dt>ev_loop_destroy (loop)</dt> |
362 | <dd> |
438 | <dd> |
363 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
439 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
364 | earlier call to <code>ev_loop_new</code>.</p> |
440 | earlier call to <code>ev_loop_new</code>.</p> |
… | |
… | |
442 | be handled here by queueing them when their watcher gets executed. |
518 | be handled here by queueing them when their watcher gets executed. |
443 | - 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 |
444 | were used, return, otherwise continue with step *. |
520 | were used, return, otherwise continue with step *. |
445 | |
521 | |
446 | </pre> |
522 | </pre> |
447 | <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 |
448 | anymore.</p> |
524 | anymore.</p> |
449 | <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 |
450 | ... 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..) |
451 | ev_loop (my_loop, 0); |
527 | ev_loop (my_loop, 0); |
452 | ... jobs done. yeah! |
528 | ... jobs done. yeah! |
… | |
… | |
471 | 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 |
472 | 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 |
473 | 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 |
474 | 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 |
475 | 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> |
476 | <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> |
477 | running when nothing else is active.</p> |
553 | running when nothing else is active.</p> |
478 | <pre> struct dv_signal exitsig; |
554 | <pre> struct ev_signal exitsig; |
479 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
555 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
480 | ev_signal_start (myloop, &exitsig); |
556 | ev_signal_start (loop, &exitsig); |
481 | evf_unref (myloop); |
557 | evf_unref (loop); |
482 | |
558 | |
483 | </pre> |
559 | </pre> |
484 | <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> |
485 | <pre> ev_ref (myloop); |
561 | <pre> ev_ref (loop); |
486 | ev_signal_stop (myloop, &exitsig); |
562 | ev_signal_stop (loop, &exitsig); |
487 | |
563 | |
488 | </pre> |
564 | </pre> |
489 | </dd> |
565 | </dd> |
490 | </dl> |
566 | </dl> |
491 | |
567 | |
|
|
568 | |
|
|
569 | |
|
|
570 | |
|
|
571 | |
492 | </div> |
572 | </div> |
493 | <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> |
494 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
574 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
495 | <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 |
496 | 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 |
497 | 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> |
498 | <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) |
… | |
… | |
525 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
605 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
526 | *)</code>), and you can stop watching for events at any time by calling the |
606 | *)</code>), and you can stop watching for events at any time by calling the |
527 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
607 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
528 | <p>As long as your watcher is active (has been started but not stopped) you |
608 | <p>As long as your watcher is active (has been started but not stopped) you |
529 | must not touch the values stored in it. Most specifically you must never |
609 | must not touch the values stored in it. Most specifically you must never |
530 | reinitialise it or call its set macro.</p> |
610 | reinitialise it or call its <code>set</code> macro.</p> |
531 | <p>You can check whether an event is active by calling the <code>ev_is_active |
|
|
532 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
|
|
533 | callback for it has not been called yet) you can use the <code>ev_is_pending |
|
|
534 | (watcher *)</code> macro.</p> |
|
|
535 | <p>Each and every callback receives the event loop pointer as first, the |
611 | <p>Each and every callback receives the event loop pointer as first, the |
536 | registered watcher structure as second, and a bitset of received events as |
612 | registered watcher structure as second, and a bitset of received events as |
537 | third argument.</p> |
613 | third argument.</p> |
538 | <p>The received events usually include a single bit per event type received |
614 | <p>The received events usually include a single bit per event type received |
539 | (you can receive multiple events at the same time). The possible bit masks |
615 | (you can receive multiple events at the same time). The possible bit masks |
… | |
… | |
559 | </dd> |
635 | </dd> |
560 | <dt><code>EV_CHILD</code></dt> |
636 | <dt><code>EV_CHILD</code></dt> |
561 | <dd> |
637 | <dd> |
562 | <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> |
563 | </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> |
564 | <dt><code>EV_IDLE</code></dt> |
644 | <dt><code>EV_IDLE</code></dt> |
565 | <dd> |
645 | <dd> |
566 | <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> |
567 | </dd> |
647 | </dd> |
568 | <dt><code>EV_PREPARE</code></dt> |
648 | <dt><code>EV_PREPARE</code></dt> |
… | |
… | |
573 | <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 |
574 | 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 |
575 | 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 |
576 | (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 |
577 | <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> |
578 | </dd> |
667 | </dd> |
579 | <dt><code>EV_ERROR</code></dt> |
668 | <dt><code>EV_ERROR</code></dt> |
580 | <dd> |
669 | <dd> |
581 | <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 |
582 | happen because the watcher could not be properly started because libev |
671 | happen because the watcher could not be properly started because libev |
… | |
… | |
590 | programs, though, so beware.</p> |
679 | programs, though, so beware.</p> |
591 | </dd> |
680 | </dd> |
592 | </dl> |
681 | </dl> |
593 | |
682 | |
594 | </div> |
683 | </div> |
|
|
684 | <h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2> |
|
|
685 | <div id="GENERIC_WATCHER_FUNCTIONS_CONTENT"> |
|
|
686 | <p>In the following description, <code>TYPE</code> stands for the watcher type, |
|
|
687 | e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> |
|
|
688 | <dl> |
|
|
689 | <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> |
|
|
690 | <dd> |
|
|
691 | <p>This macro initialises the generic portion of a watcher. The contents |
|
|
692 | of the watcher object can be arbitrary (so <code>malloc</code> will do). Only |
|
|
693 | the generic parts of the watcher are initialised, you <i>need</i> to call |
|
|
694 | the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the |
|
|
695 | type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro |
|
|
696 | which rolls both calls into one.</p> |
|
|
697 | <p>You can reinitialise a watcher at any time as long as it has been stopped |
|
|
698 | (or never started) and there are no pending events outstanding.</p> |
|
|
699 | <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
700 | int revents)</code>.</p> |
|
|
701 | </dd> |
|
|
702 | <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> |
|
|
703 | <dd> |
|
|
704 | <p>This macro initialises the type-specific parts of a watcher. You need to |
|
|
705 | call <code>ev_init</code> at least once before you call this macro, but you can |
|
|
706 | call <code>ev_TYPE_set</code> any number of times. You must not, however, call this |
|
|
707 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
708 | difference to the <code>ev_init</code> macro).</p> |
|
|
709 | <p>Although some watcher types do not have type-specific arguments |
|
|
710 | (e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p> |
|
|
711 | </dd> |
|
|
712 | <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt> |
|
|
713 | <dd> |
|
|
714 | <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro |
|
|
715 | calls into a single call. This is the most convinient method to initialise |
|
|
716 | a watcher. The same limitations apply, of course.</p> |
|
|
717 | </dd> |
|
|
718 | <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
719 | <dd> |
|
|
720 | <p>Starts (activates) the given watcher. Only active watchers will receive |
|
|
721 | events. If the watcher is already active nothing will happen.</p> |
|
|
722 | </dd> |
|
|
723 | <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
724 | <dd> |
|
|
725 | <p>Stops the given watcher again (if active) and clears the pending |
|
|
726 | status. It is possible that stopped watchers are pending (for example, |
|
|
727 | non-repeating timers are being stopped when they become pending), but |
|
|
728 | <code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If |
|
|
729 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
730 | good idea to always call its <code>ev_TYPE_stop</code> function.</p> |
|
|
731 | </dd> |
|
|
732 | <dt>bool ev_is_active (ev_TYPE *watcher)</dt> |
|
|
733 | <dd> |
|
|
734 | <p>Returns a true value iff the watcher is active (i.e. it has been started |
|
|
735 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
736 | it.</p> |
|
|
737 | </dd> |
|
|
738 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
|
|
739 | <dd> |
|
|
740 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
741 | events but its callback has not yet been invoked). As long as a watcher |
|
|
742 | is pending (but not active) you must not call an init function on it (but |
|
|
743 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
|
|
744 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
|
|
745 | </dd> |
|
|
746 | <dt>callback ev_cb (ev_TYPE *watcher)</dt> |
|
|
747 | <dd> |
|
|
748 | <p>Returns the callback currently set on the watcher.</p> |
|
|
749 | </dd> |
|
|
750 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
|
|
751 | <dd> |
|
|
752 | <p>Change the callback. You can change the callback at virtually any time |
|
|
753 | (modulo threads).</p> |
|
|
754 | </dd> |
|
|
755 | </dl> |
|
|
756 | |
|
|
757 | |
|
|
758 | |
|
|
759 | |
|
|
760 | |
|
|
761 | </div> |
595 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
762 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
596 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
763 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
597 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
764 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
598 | and read at any time, libev will completely ignore it. This can be used |
765 | and read at any time, libev will completely ignore it. This can be used |
599 | to associate arbitrary data with your watcher. If you need more data and |
766 | to associate arbitrary data with your watcher. If you need more data and |
… | |
… | |
616 | struct my_io *w = (struct my_io *)w_; |
783 | struct my_io *w = (struct my_io *)w_; |
617 | ... |
784 | ... |
618 | } |
785 | } |
619 | |
786 | |
620 | </pre> |
787 | </pre> |
621 | <p>More interesting and less C-conformant ways of catsing your callback type |
788 | <p>More interesting and less C-conformant ways of casting your callback type |
622 | have been omitted....</p> |
789 | instead have been omitted.</p> |
|
|
790 | <p>Another common scenario is having some data structure with multiple |
|
|
791 | watchers:</p> |
|
|
792 | <pre> struct my_biggy |
|
|
793 | { |
|
|
794 | int some_data; |
|
|
795 | ev_timer t1; |
|
|
796 | ev_timer t2; |
|
|
797 | } |
623 | |
798 | |
|
|
799 | </pre> |
|
|
800 | <p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated, |
|
|
801 | you need to use <code>offsetof</code>:</p> |
|
|
802 | <pre> #include <stddef.h> |
624 | |
803 | |
|
|
804 | static void |
|
|
805 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
806 | { |
|
|
807 | struct my_biggy big = (struct my_biggy * |
|
|
808 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
809 | } |
625 | |
810 | |
|
|
811 | static void |
|
|
812 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
813 | { |
|
|
814 | struct my_biggy big = (struct my_biggy * |
|
|
815 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
816 | } |
626 | |
817 | |
627 | |
818 | |
|
|
819 | |
|
|
820 | |
|
|
821 | </pre> |
|
|
822 | |
628 | </div> |
823 | </div> |
629 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
824 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1> |
630 | <div id="WATCHER_TYPES_CONTENT"> |
825 | <div id="WATCHER_TYPES_CONTENT"> |
631 | <p>This section describes each watcher in detail, but will not repeat |
826 | <p>This section describes each watcher in detail, but will not repeat |
632 | information given in the last section.</p> |
827 | information given in the last section. Any initialisation/set macros, |
|
|
828 | functions and members specific to the watcher type are explained.</p> |
|
|
829 | <p>Members are additionally marked with either <i>[read-only]</i>, meaning that, |
|
|
830 | while the watcher is active, you can look at the member and expect some |
|
|
831 | sensible content, but you must not modify it (you can modify it while the |
|
|
832 | watcher is stopped to your hearts content), or <i>[read-write]</i>, which |
|
|
833 | means you can expect it to have some sensible content while the watcher |
|
|
834 | is active, but you can also modify it. Modifying it may not do something |
|
|
835 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
836 | not crash or malfunction in any way.</p> |
633 | |
837 | |
634 | |
838 | |
635 | |
839 | |
636 | |
840 | |
637 | |
841 | |
638 | </div> |
842 | </div> |
639 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
843 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2> |
640 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
844 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
641 | <p>I/O watchers check whether a file descriptor is readable or writable |
845 | <p>I/O watchers check whether a file descriptor is readable or writable |
642 | in each iteration of the event loop (This behaviour is called |
846 | in each iteration of the event loop, or, more precisely, when reading |
643 | level-triggering because you keep receiving events as long as the |
847 | would not block the process and writing would at least be able to write |
644 | condition persists. Remember you can stop the watcher if you don't want to |
848 | some data. This behaviour is called level-triggering because you keep |
645 | act on the event and neither want to receive future events).</p> |
849 | receiving events as long as the condition persists. Remember you can stop |
|
|
850 | the watcher if you don't want to act on the event and neither want to |
|
|
851 | receive future events.</p> |
646 | <p>In general you can register as many read and/or write event watchers per |
852 | <p>In general you can register as many read and/or write event watchers per |
647 | fd as you want (as long as you don't confuse yourself). Setting all file |
853 | fd as you want (as long as you don't confuse yourself). Setting all file |
648 | descriptors to non-blocking mode is also usually a good idea (but not |
854 | descriptors to non-blocking mode is also usually a good idea (but not |
649 | required if you know what you are doing).</p> |
855 | required if you know what you are doing).</p> |
650 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
856 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
651 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
857 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
652 | descriptors correctly if you register interest in two or more fds pointing |
858 | descriptors correctly if you register interest in two or more fds pointing |
653 | to the same underlying file/socket etc. description (that is, they share |
859 | to the same underlying file/socket/etc. description (that is, they share |
654 | the same underlying "file open").</p> |
860 | the same underlying "file open").</p> |
655 | <p>If you must do this, then force the use of a known-to-be-good backend |
861 | <p>If you must do this, then force the use of a known-to-be-good backend |
656 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
862 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
657 | <code>EVBACKEND_POLL</code>).</p> |
863 | <code>EVBACKEND_POLL</code>).</p> |
|
|
864 | <p>Another thing you have to watch out for is that it is quite easy to |
|
|
865 | receive "spurious" readyness notifications, that is your callback might |
|
|
866 | be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block |
|
|
867 | because there is no data. Not only are some backends known to create a |
|
|
868 | lot of those (for example solaris ports), it is very easy to get into |
|
|
869 | this situation even with a relatively standard program structure. Thus |
|
|
870 | it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning |
|
|
871 | <code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> |
|
|
872 | <p>If you cannot run the fd in non-blocking mode (for example you should not |
|
|
873 | play around with an Xlib connection), then you have to seperately re-test |
|
|
874 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
875 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
876 | its own, so its quite safe to use).</p> |
658 | <dl> |
877 | <dl> |
659 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
878 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
660 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
879 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
661 | <dd> |
880 | <dd> |
662 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
881 | <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to |
663 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
882 | rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or |
664 | EV_WRITE</code> to receive the given events.</p> |
883 | <code>EV_READ | EV_WRITE</code> to receive the given events.</p> |
665 | <p>Please note that most of the more scalable backend mechanisms (for example |
884 | </dd> |
666 | epoll and solaris ports) can result in spurious readyness notifications |
885 | <dt>int fd [read-only]</dt> |
667 | for file descriptors, so you practically need to use non-blocking I/O (and |
886 | <dd> |
668 | treat callback invocation as hint only), or retest separately with a safe |
887 | <p>The file descriptor being watched.</p> |
669 | interface before doing I/O (XLib can do this), or force the use of either |
888 | </dd> |
670 | <code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this |
889 | <dt>int events [read-only]</dt> |
671 | problem. Also note that it is quite easy to have your callback invoked |
890 | <dd> |
672 | when the readyness condition is no longer valid even when employing |
891 | <p>The events being watched.</p> |
673 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
674 | I/O unconditionally.</p> |
|
|
675 | </dd> |
892 | </dd> |
676 | </dl> |
893 | </dl> |
677 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
894 | <p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
678 | readable, but only once. Since it is likely line-buffered, you could |
895 | readable, but only once. Since it is likely line-buffered, you could |
679 | attempt to read a whole line in the callback:</p> |
896 | attempt to read a whole line in the callback.</p> |
680 | <pre> static void |
897 | <pre> static void |
681 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
898 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
682 | { |
899 | { |
683 | ev_io_stop (loop, w); |
900 | ev_io_stop (loop, w); |
684 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
901 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
… | |
… | |
695 | |
912 | |
696 | |
913 | |
697 | </pre> |
914 | </pre> |
698 | |
915 | |
699 | </div> |
916 | </div> |
700 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
917 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2> |
701 | <div id="code_ev_timer_code_relative_and_opti-2"> |
918 | <div id="code_ev_timer_code_relative_and_opti-2"> |
702 | <p>Timer watchers are simple relative timers that generate an event after a |
919 | <p>Timer watchers are simple relative timers that generate an event after a |
703 | given time, and optionally repeating in regular intervals after that.</p> |
920 | given time, and optionally repeating in regular intervals after that.</p> |
704 | <p>The timers are based on real time, that is, if you register an event that |
921 | <p>The timers are based on real time, that is, if you register an event that |
705 | times out after an hour and you reset your system clock to last years |
922 | times out after an hour and you reset your system clock to last years |
… | |
… | |
737 | repeating. The exact semantics are:</p> |
954 | repeating. The exact semantics are:</p> |
738 | <p>If the timer is started but nonrepeating, stop it.</p> |
955 | <p>If the timer is started but nonrepeating, stop it.</p> |
739 | <p>If the timer is repeating, either start it if necessary (with the repeat |
956 | <p>If the timer is repeating, either start it if necessary (with the repeat |
740 | value), or reset the running timer to the repeat value.</p> |
957 | value), or reset the running timer to the repeat value.</p> |
741 | <p>This sounds a bit complicated, but here is a useful and typical |
958 | <p>This sounds a bit complicated, but here is a useful and typical |
742 | example: Imagine you have a tcp connection and you want a so-called idle |
959 | example: Imagine you have a tcp connection and you want a so-called |
743 | timeout, that is, you want to be called when there have been, say, 60 |
960 | idle timeout, that is, you want to be called when there have been, |
744 | seconds of inactivity on the socket. The easiest way to do this is to |
961 | say, 60 seconds of inactivity on the socket. The easiest way to do |
745 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
962 | this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling |
746 | time you successfully read or write some data. If you go into an idle |
963 | <code>ev_timer_again</code> each time you successfully read or write some data. If |
747 | state where you do not expect data to travel on the socket, you can stop |
964 | you go into an idle state where you do not expect data to travel on the |
748 | the timer, and again will automatically restart it if need be.</p> |
965 | socket, you can stop the timer, and again will automatically restart it if |
|
|
966 | need be.</p> |
|
|
967 | <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether |
|
|
968 | and only ever use the <code>repeat</code> value:</p> |
|
|
969 | <pre> ev_timer_init (timer, callback, 0., 5.); |
|
|
970 | ev_timer_again (loop, timer); |
|
|
971 | ... |
|
|
972 | timer->again = 17.; |
|
|
973 | ev_timer_again (loop, timer); |
|
|
974 | ... |
|
|
975 | timer->again = 10.; |
|
|
976 | ev_timer_again (loop, timer); |
|
|
977 | |
|
|
978 | </pre> |
|
|
979 | <p>This is more efficient then stopping/starting the timer eahc time you want |
|
|
980 | to modify its timeout value.</p> |
|
|
981 | </dd> |
|
|
982 | <dt>ev_tstamp repeat [read-write]</dt> |
|
|
983 | <dd> |
|
|
984 | <p>The current <code>repeat</code> value. Will be used each time the watcher times out |
|
|
985 | or <code>ev_timer_again</code> is called and determines the next timeout (if any), |
|
|
986 | which is also when any modifications are taken into account.</p> |
749 | </dd> |
987 | </dd> |
750 | </dl> |
988 | </dl> |
751 | <p>Example: create a timer that fires after 60 seconds.</p> |
989 | <p>Example: Create a timer that fires after 60 seconds.</p> |
752 | <pre> static void |
990 | <pre> static void |
753 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
991 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
754 | { |
992 | { |
755 | .. one minute over, w is actually stopped right here |
993 | .. one minute over, w is actually stopped right here |
756 | } |
994 | } |
… | |
… | |
758 | struct ev_timer mytimer; |
996 | struct ev_timer mytimer; |
759 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
997 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
760 | ev_timer_start (loop, &mytimer); |
998 | ev_timer_start (loop, &mytimer); |
761 | |
999 | |
762 | </pre> |
1000 | </pre> |
763 | <p>Example: create a timeout timer that times out after 10 seconds of |
1001 | <p>Example: Create a timeout timer that times out after 10 seconds of |
764 | inactivity.</p> |
1002 | inactivity.</p> |
765 | <pre> static void |
1003 | <pre> static void |
766 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1004 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
767 | { |
1005 | { |
768 | .. ten seconds without any activity |
1006 | .. ten seconds without any activity |
… | |
… | |
781 | |
1019 | |
782 | |
1020 | |
783 | </pre> |
1021 | </pre> |
784 | |
1022 | |
785 | </div> |
1023 | </div> |
786 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
1024 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2> |
787 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
1025 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
788 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
1026 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
789 | (and unfortunately a bit complex).</p> |
1027 | (and unfortunately a bit complex).</p> |
790 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
1028 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
791 | but on wallclock time (absolute time). You can tell a periodic watcher |
1029 | but on wallclock time (absolute time). You can tell a periodic watcher |
792 | to trigger "at" some specific point in time. For example, if you tell a |
1030 | to trigger "at" some specific point in time. For example, if you tell a |
793 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
1031 | periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () |
794 | + 10.>) and then reset your system clock to the last year, then it will |
1032 | + 10.</code>) and then reset your system clock to the last year, then it will |
795 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
1033 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
796 | roughly 10 seconds later and of course not if you reset your system time |
1034 | roughly 10 seconds later and of course not if you reset your system time |
797 | again).</p> |
1035 | again).</p> |
798 | <p>They can also be used to implement vastly more complex timers, such as |
1036 | <p>They can also be used to implement vastly more complex timers, such as |
799 | triggering an event on eahc midnight, local time.</p> |
1037 | triggering an event on eahc midnight, local time.</p> |
… | |
… | |
871 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
1109 | <p>Simply stops and restarts the periodic watcher again. This is only useful |
872 | when you changed some parameters or the reschedule callback would return |
1110 | when you changed some parameters or the reschedule callback would return |
873 | a different time than the last time it was called (e.g. in a crond like |
1111 | a different time than the last time it was called (e.g. in a crond like |
874 | program when the crontabs have changed).</p> |
1112 | program when the crontabs have changed).</p> |
875 | </dd> |
1113 | </dd> |
|
|
1114 | <dt>ev_tstamp interval [read-write]</dt> |
|
|
1115 | <dd> |
|
|
1116 | <p>The current interval value. Can be modified any time, but changes only |
|
|
1117 | take effect when the periodic timer fires or <code>ev_periodic_again</code> is being |
|
|
1118 | called.</p> |
|
|
1119 | </dd> |
|
|
1120 | <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt> |
|
|
1121 | <dd> |
|
|
1122 | <p>The current reschedule callback, or <code>0</code>, if this functionality is |
|
|
1123 | switched off. Can be changed any time, but changes only take effect when |
|
|
1124 | the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> |
|
|
1125 | </dd> |
876 | </dl> |
1126 | </dl> |
877 | <p>Example: call a callback every hour, or, more precisely, whenever the |
1127 | <p>Example: Call a callback every hour, or, more precisely, whenever the |
878 | system clock is divisible by 3600. The callback invocation times have |
1128 | system clock is divisible by 3600. The callback invocation times have |
879 | potentially a lot of jittering, but good long-term stability.</p> |
1129 | potentially a lot of jittering, but good long-term stability.</p> |
880 | <pre> static void |
1130 | <pre> static void |
881 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1131 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
882 | { |
1132 | { |
… | |
… | |
886 | struct ev_periodic hourly_tick; |
1136 | struct ev_periodic hourly_tick; |
887 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1137 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
888 | ev_periodic_start (loop, &hourly_tick); |
1138 | ev_periodic_start (loop, &hourly_tick); |
889 | |
1139 | |
890 | </pre> |
1140 | </pre> |
891 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
1141 | <p>Example: The same as above, but use a reschedule callback to do it:</p> |
892 | <pre> #include <math.h> |
1142 | <pre> #include <math.h> |
893 | |
1143 | |
894 | static ev_tstamp |
1144 | static ev_tstamp |
895 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1145 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
896 | { |
1146 | { |
… | |
… | |
898 | } |
1148 | } |
899 | |
1149 | |
900 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1150 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
901 | |
1151 | |
902 | </pre> |
1152 | </pre> |
903 | <p>Example: call a callback every hour, starting now:</p> |
1153 | <p>Example: Call a callback every hour, starting now:</p> |
904 | <pre> struct ev_periodic hourly_tick; |
1154 | <pre> struct ev_periodic hourly_tick; |
905 | ev_periodic_init (&hourly_tick, clock_cb, |
1155 | ev_periodic_init (&hourly_tick, clock_cb, |
906 | fmod (ev_now (loop), 3600.), 3600., 0); |
1156 | fmod (ev_now (loop), 3600.), 3600., 0); |
907 | ev_periodic_start (loop, &hourly_tick); |
1157 | ev_periodic_start (loop, &hourly_tick); |
908 | |
1158 | |
… | |
… | |
910 | |
1160 | |
911 | |
1161 | |
912 | </pre> |
1162 | </pre> |
913 | |
1163 | |
914 | </div> |
1164 | </div> |
915 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
1165 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2> |
916 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
1166 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
917 | <p>Signal watchers will trigger an event when the process receives a specific |
1167 | <p>Signal watchers will trigger an event when the process receives a specific |
918 | signal one or more times. Even though signals are very asynchronous, libev |
1168 | signal one or more times. Even though signals are very asynchronous, libev |
919 | will try it's best to deliver signals synchronously, i.e. as part of the |
1169 | will try it's best to deliver signals synchronously, i.e. as part of the |
920 | normal event processing, like any other event.</p> |
1170 | normal event processing, like any other event.</p> |
… | |
… | |
929 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
1179 | <dt>ev_signal_set (ev_signal *, int signum)</dt> |
930 | <dd> |
1180 | <dd> |
931 | <p>Configures the watcher to trigger on the given signal number (usually one |
1181 | <p>Configures the watcher to trigger on the given signal number (usually one |
932 | of the <code>SIGxxx</code> constants).</p> |
1182 | of the <code>SIGxxx</code> constants).</p> |
933 | </dd> |
1183 | </dd> |
|
|
1184 | <dt>int signum [read-only]</dt> |
|
|
1185 | <dd> |
|
|
1186 | <p>The signal the watcher watches out for.</p> |
|
|
1187 | </dd> |
934 | </dl> |
1188 | </dl> |
935 | |
1189 | |
|
|
1190 | |
|
|
1191 | |
|
|
1192 | |
|
|
1193 | |
936 | </div> |
1194 | </div> |
937 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
1195 | <h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> |
938 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
1196 | <div id="code_ev_child_code_watch_out_for_pro-2"> |
939 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
1197 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
940 | some child status changes (most typically when a child of yours dies).</p> |
1198 | some child status changes (most typically when a child of yours dies).</p> |
941 | <dl> |
1199 | <dl> |
942 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1200 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
943 | <dt>ev_child_set (ev_child *, int pid)</dt> |
1201 | <dt>ev_child_set (ev_child *, int pid)</dt> |
… | |
… | |
947 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
1205 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
948 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
1206 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
949 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
1207 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
950 | process causing the status change.</p> |
1208 | process causing the status change.</p> |
951 | </dd> |
1209 | </dd> |
|
|
1210 | <dt>int pid [read-only]</dt> |
|
|
1211 | <dd> |
|
|
1212 | <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p> |
|
|
1213 | </dd> |
|
|
1214 | <dt>int rpid [read-write]</dt> |
|
|
1215 | <dd> |
|
|
1216 | <p>The process id that detected a status change.</p> |
|
|
1217 | </dd> |
|
|
1218 | <dt>int rstatus [read-write]</dt> |
|
|
1219 | <dd> |
|
|
1220 | <p>The process exit/trace status caused by <code>rpid</code> (see your systems |
|
|
1221 | <code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> |
|
|
1222 | </dd> |
952 | </dl> |
1223 | </dl> |
953 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
1224 | <p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p> |
954 | <pre> static void |
1225 | <pre> static void |
955 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1226 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
956 | { |
1227 | { |
957 | ev_unloop (loop, EVUNLOOP_ALL); |
1228 | ev_unloop (loop, EVUNLOOP_ALL); |
958 | } |
1229 | } |
… | |
… | |
965 | |
1236 | |
966 | |
1237 | |
967 | </pre> |
1238 | </pre> |
968 | |
1239 | |
969 | </div> |
1240 | </div> |
|
|
1241 | <h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2> |
|
|
1242 | <div id="code_ev_stat_code_did_the_file_attri-2"> |
|
|
1243 | <p>This watches a filesystem path for attribute changes. That is, it calls |
|
|
1244 | <code>stat</code> regularly (or when the OS says it changed) and sees if it changed |
|
|
1245 | compared to the last time, invoking the callback if it did.</p> |
|
|
1246 | <p>The path does not need to exist: changing from "path exists" to "path does |
|
|
1247 | not exist" is a status change like any other. The condition "path does |
|
|
1248 | not exist" is signified by the <code>st_nlink</code> field being zero (which is |
|
|
1249 | otherwise always forced to be at least one) and all the other fields of |
|
|
1250 | the stat buffer having unspecified contents.</p> |
|
|
1251 | <p>Since there is no standard to do this, the portable implementation simply |
|
|
1252 | calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You |
|
|
1253 | can specify a recommended polling interval for this case. If you specify |
|
|
1254 | a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, |
|
|
1255 | unspecified default</i> value will be used (which you can expect to be around |
|
|
1256 | five seconds, although this might change dynamically). Libev will also |
|
|
1257 | impose a minimum interval which is currently around <code>0.1</code>, but thats |
|
|
1258 | usually overkill.</p> |
|
|
1259 | <p>This watcher type is not meant for massive numbers of stat watchers, |
|
|
1260 | as even with OS-supported change notifications, this can be |
|
|
1261 | resource-intensive.</p> |
|
|
1262 | <p>At the time of this writing, only the Linux inotify interface is |
|
|
1263 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1264 | reader). Inotify will be used to give hints only and should not change the |
|
|
1265 | semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs |
|
|
1266 | to fall back to regular polling again even with inotify, but changes are |
|
|
1267 | usually detected immediately, and if the file exists there will be no |
|
|
1268 | polling.</p> |
|
|
1269 | <dl> |
|
|
1270 | <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> |
|
|
1271 | <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> |
|
|
1272 | <dd> |
|
|
1273 | <p>Configures the watcher to wait for status changes of the given |
|
|
1274 | <code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to |
|
|
1275 | be detected and should normally be specified as <code>0</code> to let libev choose |
|
|
1276 | a suitable value. The memory pointed to by <code>path</code> must point to the same |
|
|
1277 | path for as long as the watcher is active.</p> |
|
|
1278 | <p>The callback will be receive <code>EV_STAT</code> when a change was detected, |
|
|
1279 | relative to the attributes at the time the watcher was started (or the |
|
|
1280 | last change was detected).</p> |
|
|
1281 | </dd> |
|
|
1282 | <dt>ev_stat_stat (ev_stat *)</dt> |
|
|
1283 | <dd> |
|
|
1284 | <p>Updates the stat buffer immediately with new values. If you change the |
|
|
1285 | watched path in your callback, you could call this fucntion to avoid |
|
|
1286 | detecting this change (while introducing a race condition). Can also be |
|
|
1287 | useful simply to find out the new values.</p> |
|
|
1288 | </dd> |
|
|
1289 | <dt>ev_statdata attr [read-only]</dt> |
|
|
1290 | <dd> |
|
|
1291 | <p>The most-recently detected attributes of the file. Although the type is of |
|
|
1292 | <code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types |
|
|
1293 | suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there |
|
|
1294 | was some error while <code>stat</code>ing the file.</p> |
|
|
1295 | </dd> |
|
|
1296 | <dt>ev_statdata prev [read-only]</dt> |
|
|
1297 | <dd> |
|
|
1298 | <p>The previous attributes of the file. The callback gets invoked whenever |
|
|
1299 | <code>prev</code> != <code>attr</code>.</p> |
|
|
1300 | </dd> |
|
|
1301 | <dt>ev_tstamp interval [read-only]</dt> |
|
|
1302 | <dd> |
|
|
1303 | <p>The specified interval.</p> |
|
|
1304 | </dd> |
|
|
1305 | <dt>const char *path [read-only]</dt> |
|
|
1306 | <dd> |
|
|
1307 | <p>The filesystem path that is being watched.</p> |
|
|
1308 | </dd> |
|
|
1309 | </dl> |
|
|
1310 | <p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p> |
|
|
1311 | <pre> static void |
|
|
1312 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1313 | { |
|
|
1314 | /* /etc/passwd changed in some way */ |
|
|
1315 | if (w->attr.st_nlink) |
|
|
1316 | { |
|
|
1317 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1318 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1319 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1320 | } |
|
|
1321 | else |
|
|
1322 | /* you shalt not abuse printf for puts */ |
|
|
1323 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1324 | "if this is windows, they already arrived\n"); |
|
|
1325 | } |
|
|
1326 | |
|
|
1327 | ... |
|
|
1328 | ev_stat passwd; |
|
|
1329 | |
|
|
1330 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1331 | ev_stat_start (loop, &passwd); |
|
|
1332 | |
|
|
1333 | |
|
|
1334 | |
|
|
1335 | |
|
|
1336 | </pre> |
|
|
1337 | |
|
|
1338 | </div> |
970 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
1339 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> |
971 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
1340 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
972 | <p>Idle watchers trigger events when there are no other events are pending |
1341 | <p>Idle watchers trigger events when there are no other events are pending |
973 | (prepare, check and other idle watchers do not count). That is, as long |
1342 | (prepare, check and other idle watchers do not count). That is, as long |
974 | as your process is busy handling sockets or timeouts (or even signals, |
1343 | as your process is busy handling sockets or timeouts (or even signals, |
975 | imagine) it will not be triggered. But when your process is idle all idle |
1344 | imagine) it will not be triggered. But when your process is idle all idle |
… | |
… | |
988 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1357 | <p>Initialises and configures the idle watcher - it has no parameters of any |
989 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1358 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
990 | believe me.</p> |
1359 | believe me.</p> |
991 | </dd> |
1360 | </dd> |
992 | </dl> |
1361 | </dl> |
993 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
1362 | <p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the |
994 | callback, free it. Alos, use no error checking, as usual.</p> |
1363 | callback, free it. Also, use no error checking, as usual.</p> |
995 | <pre> static void |
1364 | <pre> static void |
996 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1365 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
997 | { |
1366 | { |
998 | free (w); |
1367 | free (w); |
999 | // now do something you wanted to do when the program has |
1368 | // now do something you wanted to do when the program has |
… | |
… | |
1008 | |
1377 | |
1009 | |
1378 | |
1010 | </pre> |
1379 | </pre> |
1011 | |
1380 | |
1012 | </div> |
1381 | </div> |
1013 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
1382 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2> |
1014 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1383 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
1015 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1384 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
1016 | prepare watchers get invoked before the process blocks and check watchers |
1385 | prepare watchers get invoked before the process blocks and check watchers |
1017 | afterwards.</p> |
1386 | afterwards.</p> |
|
|
1387 | <p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter |
|
|
1388 | the current event loop from either <code>ev_prepare</code> or <code>ev_check</code> |
|
|
1389 | watchers. Other loops than the current one are fine, however. The |
|
|
1390 | rationale behind this is that you do not need to check for recursion in |
|
|
1391 | those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking, |
|
|
1392 | <code>ev_check</code> so if you have one watcher of each kind they will always be |
|
|
1393 | called in pairs bracketing the blocking call.</p> |
1018 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
1394 | <p>Their main purpose is to integrate other event mechanisms into libev and |
1019 | could be used, for example, to track variable changes, implement your own |
1395 | their use is somewhat advanced. This could be used, for example, to track |
1020 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
1396 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1397 | coroutine library and lots more. They are also occasionally useful if |
|
|
1398 | you cache some data and want to flush it before blocking (for example, |
|
|
1399 | in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code> |
|
|
1400 | watcher).</p> |
1021 | <p>This is done by examining in each prepare call which file descriptors need |
1401 | <p>This is done by examining in each prepare call which file descriptors need |
1022 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1402 | to be watched by the other library, registering <code>ev_io</code> watchers for |
1023 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1403 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
1024 | provide just this functionality). Then, in the check watcher you check for |
1404 | provide just this functionality). Then, in the check watcher you check for |
1025 | any events that occured (by checking the pending status of all watchers |
1405 | any events that occured (by checking the pending status of all watchers |
… | |
… | |
1041 | <p>Initialises and configures the prepare or check watcher - they have no |
1421 | <p>Initialises and configures the prepare or check watcher - they have no |
1042 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1422 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
1043 | macros, but using them is utterly, utterly and completely pointless.</p> |
1423 | macros, but using them is utterly, utterly and completely pointless.</p> |
1044 | </dd> |
1424 | </dd> |
1045 | </dl> |
1425 | </dl> |
1046 | <p>Example: *TODO*.</p> |
1426 | <p>Example: To include a library such as adns, you would add IO watchers |
|
|
1427 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1428 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1429 | pseudo-code only of course:</p> |
|
|
1430 | <pre> static ev_io iow [nfd]; |
|
|
1431 | static ev_timer tw; |
1047 | |
1432 | |
|
|
1433 | static void |
|
|
1434 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1435 | { |
|
|
1436 | // set the relevant poll flags |
|
|
1437 | // could also call adns_processreadable etc. here |
|
|
1438 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1439 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1440 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1441 | } |
1048 | |
1442 | |
|
|
1443 | // create io watchers for each fd and a timer before blocking |
|
|
1444 | static void |
|
|
1445 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1446 | { |
|
|
1447 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1448 | // actual code will need to loop here and realloc etc. |
|
|
1449 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1049 | |
1450 | |
|
|
1451 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1452 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1453 | ev_timer_start (loop, &tw); |
1050 | |
1454 | |
|
|
1455 | // create on ev_io per pollfd |
|
|
1456 | for (int i = 0; i < nfd; ++i) |
|
|
1457 | { |
|
|
1458 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1459 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1460 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1051 | |
1461 | |
|
|
1462 | fds [i].revents = 0; |
|
|
1463 | iow [i].data = fds + i; |
|
|
1464 | ev_io_start (loop, iow + i); |
|
|
1465 | } |
|
|
1466 | } |
|
|
1467 | |
|
|
1468 | // stop all watchers after blocking |
|
|
1469 | static void |
|
|
1470 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1471 | { |
|
|
1472 | ev_timer_stop (loop, &tw); |
|
|
1473 | |
|
|
1474 | for (int i = 0; i < nfd; ++i) |
|
|
1475 | ev_io_stop (loop, iow + i); |
|
|
1476 | |
|
|
1477 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1478 | } |
|
|
1479 | |
|
|
1480 | |
|
|
1481 | |
|
|
1482 | |
|
|
1483 | </pre> |
|
|
1484 | |
1052 | </div> |
1485 | </div> |
1053 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1486 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2> |
|
|
1487 | <div id="code_ev_embed_code_when_one_backend_-2"> |
|
|
1488 | <p>This is a rather advanced watcher type that lets you embed one event loop |
|
|
1489 | into another (currently only <code>ev_io</code> events are supported in the embedded |
|
|
1490 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1491 | fashion and must not be used).</p> |
|
|
1492 | <p>There are primarily two reasons you would want that: work around bugs and |
|
|
1493 | prioritise I/O.</p> |
|
|
1494 | <p>As an example for a bug workaround, the kqueue backend might only support |
|
|
1495 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1496 | still want to make use of it because you have many sockets and it scales |
|
|
1497 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1498 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1499 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1500 | at least you can use both at what they are best.</p> |
|
|
1501 | <p>As for prioritising I/O: rarely you have the case where some fds have |
|
|
1502 | to be watched and handled very quickly (with low latency), and even |
|
|
1503 | priorities and idle watchers might have too much overhead. In this case |
|
|
1504 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1505 | a second one, and embed the second one in the first.</p> |
|
|
1506 | <p>As long as the watcher is active, the callback will be invoked every time |
|
|
1507 | there might be events pending in the embedded loop. The callback must then |
|
|
1508 | call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke |
|
|
1509 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1510 | loop strictly lower priority for example). You can also set the callback |
|
|
1511 | to <code>0</code>, in which case the embed watcher will automatically execute the |
|
|
1512 | embedded loop sweep.</p> |
|
|
1513 | <p>As long as the watcher is started it will automatically handle events. The |
|
|
1514 | callback will be invoked whenever some events have been handled. You can |
|
|
1515 | set the callback to <code>0</code> to avoid having to specify one if you are not |
|
|
1516 | interested in that.</p> |
|
|
1517 | <p>Also, there have not currently been made special provisions for forking: |
|
|
1518 | when you fork, you not only have to call <code>ev_loop_fork</code> on both loops, |
|
|
1519 | but you will also have to stop and restart any <code>ev_embed</code> watchers |
|
|
1520 | yourself.</p> |
|
|
1521 | <p>Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1522 | <code>ev_embeddable_backends</code> are, which, unfortunately, does not include any |
|
|
1523 | portable one.</p> |
|
|
1524 | <p>So when you want to use this feature you will always have to be prepared |
|
|
1525 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1526 | this is to have a separate variables for your embeddable loop, try to |
|
|
1527 | create it, and if that fails, use the normal loop for everything:</p> |
|
|
1528 | <pre> struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1529 | struct ev_loop *loop_lo = 0; |
|
|
1530 | struct ev_embed embed; |
|
|
1531 | |
|
|
1532 | // see if there is a chance of getting one that works |
|
|
1533 | // (remember that a flags value of 0 means autodetection) |
|
|
1534 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1535 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1536 | : 0; |
|
|
1537 | |
|
|
1538 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1539 | if (loop_lo) |
|
|
1540 | { |
|
|
1541 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1542 | ev_embed_start (loop_hi, &embed); |
|
|
1543 | } |
|
|
1544 | else |
|
|
1545 | loop_lo = loop_hi; |
|
|
1546 | |
|
|
1547 | </pre> |
|
|
1548 | <dl> |
|
|
1549 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1550 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1551 | <dd> |
|
|
1552 | <p>Configures the watcher to embed the given loop, which must be |
|
|
1553 | embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be |
|
|
1554 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1555 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1556 | if you do not want thta, you need to temporarily stop the embed watcher).</p> |
|
|
1557 | </dd> |
|
|
1558 | <dt>ev_embed_sweep (loop, ev_embed *)</dt> |
|
|
1559 | <dd> |
|
|
1560 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1561 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
|
|
1562 | apropriate way for embedded loops.</p> |
|
|
1563 | </dd> |
|
|
1564 | <dt>struct ev_loop *loop [read-only]</dt> |
|
|
1565 | <dd> |
|
|
1566 | <p>The embedded event loop.</p> |
|
|
1567 | </dd> |
|
|
1568 | </dl> |
|
|
1569 | |
|
|
1570 | |
|
|
1571 | |
|
|
1572 | |
|
|
1573 | |
|
|
1574 | </div> |
|
|
1575 | <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> |
|
|
1576 | <div id="code_ev_fork_code_the_audacity_to_re-2"> |
|
|
1577 | <p>Fork watchers are called when a <code>fork ()</code> was detected (usually because |
|
|
1578 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1579 | <code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the |
|
|
1580 | event loop blocks next and before <code>ev_check</code> watchers are being called, |
|
|
1581 | and only in the child after the fork. If whoever good citizen calling |
|
|
1582 | <code>ev_default_fork</code> cheats and calls it in the wrong process, the fork |
|
|
1583 | handlers will be invoked, too, of course.</p> |
|
|
1584 | <dl> |
|
|
1585 | <dt>ev_fork_init (ev_signal *, callback)</dt> |
|
|
1586 | <dd> |
|
|
1587 | <p>Initialises and configures the fork watcher - it has no parameters of any |
|
|
1588 | kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless, |
|
|
1589 | believe me.</p> |
|
|
1590 | </dd> |
|
|
1591 | </dl> |
|
|
1592 | |
|
|
1593 | |
|
|
1594 | |
|
|
1595 | |
|
|
1596 | |
|
|
1597 | </div> |
|
|
1598 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1> |
1054 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1599 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1055 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1600 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
1056 | <dl> |
1601 | <dl> |
1057 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1602 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1058 | <dd> |
1603 | <dd> |
… | |
… | |
1082 | |
1627 | |
1083 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1628 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1084 | |
1629 | |
1085 | </pre> |
1630 | </pre> |
1086 | </dd> |
1631 | </dd> |
1087 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
1632 | <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt> |
1088 | <dd> |
1633 | <dd> |
1089 | <p>Feeds the given event set into the event loop, as if the specified event |
1634 | <p>Feeds the given event set into the event loop, as if the specified event |
1090 | had happened for the specified watcher (which must be a pointer to an |
1635 | had happened for the specified watcher (which must be a pointer to an |
1091 | initialised but not necessarily started event watcher).</p> |
1636 | initialised but not necessarily started event watcher).</p> |
1092 | </dd> |
1637 | </dd> |
1093 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
1638 | <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt> |
1094 | <dd> |
1639 | <dd> |
1095 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
1640 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
1096 | the given events it.</p> |
1641 | the given events it.</p> |
1097 | </dd> |
1642 | </dd> |
1098 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
1643 | <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt> |
1099 | <dd> |
1644 | <dd> |
1100 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
1645 | <p>Feed an event as if the given signal occured (<code>loop</code> must be the default |
|
|
1646 | loop!).</p> |
1101 | </dd> |
1647 | </dd> |
1102 | </dl> |
1648 | </dl> |
1103 | |
1649 | |
1104 | |
1650 | |
1105 | |
1651 | |
1106 | |
1652 | |
1107 | |
1653 | |
1108 | </div> |
1654 | </div> |
1109 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1655 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1> |
1110 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1656 | <div id="LIBEVENT_EMULATION_CONTENT"> |
1111 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1657 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
1112 | emulate the internals of libevent, so here are some usage hints:</p> |
1658 | emulate the internals of libevent, so here are some usage hints:</p> |
1113 | <dl> |
1659 | <dl> |
1114 | <dt>* Use it by including <event.h>, as usual.</dt> |
1660 | <dt>* Use it by including <event.h>, as usual.</dt> |
… | |
… | |
1124 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1670 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
1125 | to use the libev header file and library.</dt> |
1671 | to use the libev header file and library.</dt> |
1126 | </dl> |
1672 | </dl> |
1127 | |
1673 | |
1128 | </div> |
1674 | </div> |
1129 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1675 | <h1 id="C_SUPPORT">C++ SUPPORT</h1> |
1130 | <div id="C_SUPPORT_CONTENT"> |
1676 | <div id="C_SUPPORT_CONTENT"> |
1131 | <p>TBD.</p> |
1677 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1678 | you to use some convinience methods to start/stop watchers and also change |
|
|
1679 | the callback model to a model using method callbacks on objects.</p> |
|
|
1680 | <p>To use it,</p> |
|
|
1681 | <pre> #include <ev++.h> |
1132 | |
1682 | |
|
|
1683 | </pre> |
|
|
1684 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
|
|
1685 | and puts all of its definitions (many of them macros) into the global |
|
|
1686 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
|
|
1687 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
|
|
1688 | <code>EV_MULTIPLICITY</code>.</p> |
|
|
1689 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
|
|
1690 | <dl> |
|
|
1691 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
|
|
1692 | <dd> |
|
|
1693 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
|
|
1694 | macros from <cite>ev.h</cite>.</p> |
|
|
1695 | </dd> |
|
|
1696 | <dt><code>ev::tstamp</code>, <code>ev::now</code></dt> |
|
|
1697 | <dd> |
|
|
1698 | <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p> |
|
|
1699 | </dd> |
|
|
1700 | <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt> |
|
|
1701 | <dd> |
|
|
1702 | <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of |
|
|
1703 | the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code> |
|
|
1704 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
|
|
1705 | defines by many implementations.</p> |
|
|
1706 | <p>All of those classes have these methods:</p> |
|
|
1707 | <p> |
|
|
1708 | <dl> |
|
|
1709 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
|
|
1710 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
|
|
1711 | <dt>ev::TYPE::~TYPE</dt> |
|
|
1712 | <dd> |
|
|
1713 | <p>The constructor takes a pointer to an object and a method pointer to |
|
|
1714 | the event handler callback to call in this class. The constructor calls |
|
|
1715 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
|
|
1716 | before starting it. If you do not specify a loop then the constructor |
|
|
1717 | automatically associates the default loop with this watcher.</p> |
|
|
1718 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1719 | </dd> |
|
|
1720 | <dt>w->set (struct ev_loop *)</dt> |
|
|
1721 | <dd> |
|
|
1722 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
|
|
1723 | do this when the watcher is inactive (and not pending either).</p> |
|
|
1724 | </dd> |
|
|
1725 | <dt>w->set ([args])</dt> |
|
|
1726 | <dd> |
|
|
1727 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
|
|
1728 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1729 | automatically stopped and restarted.</p> |
|
|
1730 | </dd> |
|
|
1731 | <dt>w->start ()</dt> |
|
|
1732 | <dd> |
|
|
1733 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
|
|
1734 | constructor already takes the loop.</p> |
|
|
1735 | </dd> |
|
|
1736 | <dt>w->stop ()</dt> |
|
|
1737 | <dd> |
|
|
1738 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
|
|
1739 | </dd> |
|
|
1740 | <dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt> |
|
|
1741 | <dd> |
|
|
1742 | <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding |
|
|
1743 | <code>ev_TYPE_again</code> function.</p> |
|
|
1744 | </dd> |
|
|
1745 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
|
|
1746 | <dd> |
|
|
1747 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
|
|
1748 | </dd> |
|
|
1749 | <dt>w->update () <code>ev::stat</code> only</dt> |
|
|
1750 | <dd> |
|
|
1751 | <p>Invokes <code>ev_stat_stat</code>.</p> |
|
|
1752 | </dd> |
|
|
1753 | </dl> |
|
|
1754 | </p> |
|
|
1755 | </dd> |
|
|
1756 | </dl> |
|
|
1757 | <p>Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1758 | the constructor.</p> |
|
|
1759 | <pre> class myclass |
|
|
1760 | { |
|
|
1761 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1762 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1763 | |
|
|
1764 | myclass (); |
|
|
1765 | } |
|
|
1766 | |
|
|
1767 | myclass::myclass (int fd) |
|
|
1768 | : io (this, &myclass::io_cb), |
|
|
1769 | idle (this, &myclass::idle_cb) |
|
|
1770 | { |
|
|
1771 | io.start (fd, ev::READ); |
|
|
1772 | } |
|
|
1773 | |
|
|
1774 | |
|
|
1775 | |
|
|
1776 | |
|
|
1777 | </pre> |
|
|
1778 | |
1133 | </div> |
1779 | </div> |
1134 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1780 | <h1 id="MACRO_MAGIC">MACRO MAGIC</h1> |
|
|
1781 | <div id="MACRO_MAGIC_CONTENT"> |
|
|
1782 | <p>Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1783 | <code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and |
|
|
1784 | callbacks have an initial <code>struct ev_loop *</code> argument.</p> |
|
|
1785 | <p>To make it easier to write programs that cope with either variant, the |
|
|
1786 | following macros are defined:</p> |
|
|
1787 | <dl> |
|
|
1788 | <dt><code>EV_A</code>, <code>EV_A_</code></dt> |
|
|
1789 | <dd> |
|
|
1790 | <p>This provides the loop <i>argument</i> for functions, if one is required ("ev |
|
|
1791 | loop argument"). The <code>EV_A</code> form is used when this is the sole argument, |
|
|
1792 | <code>EV_A_</code> is used when other arguments are following. Example:</p> |
|
|
1793 | <pre> ev_unref (EV_A); |
|
|
1794 | ev_timer_add (EV_A_ watcher); |
|
|
1795 | ev_loop (EV_A_ 0); |
|
|
1796 | |
|
|
1797 | </pre> |
|
|
1798 | <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope, |
|
|
1799 | which is often provided by the following macro.</p> |
|
|
1800 | </dd> |
|
|
1801 | <dt><code>EV_P</code>, <code>EV_P_</code></dt> |
|
|
1802 | <dd> |
|
|
1803 | <p>This provides the loop <i>parameter</i> for functions, if one is required ("ev |
|
|
1804 | loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter, |
|
|
1805 | <code>EV_P_</code> is used when other parameters are following. Example:</p> |
|
|
1806 | <pre> // this is how ev_unref is being declared |
|
|
1807 | static void ev_unref (EV_P); |
|
|
1808 | |
|
|
1809 | // this is how you can declare your typical callback |
|
|
1810 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1811 | |
|
|
1812 | </pre> |
|
|
1813 | <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite |
|
|
1814 | suitable for use with <code>EV_A</code>.</p> |
|
|
1815 | </dd> |
|
|
1816 | <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt> |
|
|
1817 | <dd> |
|
|
1818 | <p>Similar to the other two macros, this gives you the value of the default |
|
|
1819 | loop, if multiple loops are supported ("ev loop default").</p> |
|
|
1820 | </dd> |
|
|
1821 | </dl> |
|
|
1822 | <p>Example: Declare and initialise a check watcher, working regardless of |
|
|
1823 | wether multiple loops are supported or not.</p> |
|
|
1824 | <pre> static void |
|
|
1825 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1826 | { |
|
|
1827 | ev_check_stop (EV_A_ w); |
|
|
1828 | } |
|
|
1829 | |
|
|
1830 | ev_check check; |
|
|
1831 | ev_check_init (&check, check_cb); |
|
|
1832 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1833 | ev_loop (EV_DEFAULT_ 0); |
|
|
1834 | |
|
|
1835 | |
|
|
1836 | |
|
|
1837 | |
|
|
1838 | </pre> |
|
|
1839 | |
|
|
1840 | </div> |
|
|
1841 | <h1 id="EMBEDDING">EMBEDDING</h1> |
|
|
1842 | <div id="EMBEDDING_CONTENT"> |
|
|
1843 | <p>Libev can (and often is) directly embedded into host |
|
|
1844 | applications. Examples of applications that embed it include the Deliantra |
|
|
1845 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1846 | and rxvt-unicode.</p> |
|
|
1847 | <p>The goal is to enable you to just copy the neecssary files into your |
|
|
1848 | source directory without having to change even a single line in them, so |
|
|
1849 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1850 | libev somewhere in your source tree).</p> |
|
|
1851 | |
|
|
1852 | </div> |
|
|
1853 | <h2 id="FILESETS">FILESETS</h2> |
|
|
1854 | <div id="FILESETS_CONTENT"> |
|
|
1855 | <p>Depending on what features you need you need to include one or more sets of files |
|
|
1856 | in your app.</p> |
|
|
1857 | |
|
|
1858 | </div> |
|
|
1859 | <h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3> |
|
|
1860 | <div id="CORE_EVENT_LOOP_CONTENT"> |
|
|
1861 | <p>To include only the libev core (all the <code>ev_*</code> functions), with manual |
|
|
1862 | configuration (no autoconf):</p> |
|
|
1863 | <pre> #define EV_STANDALONE 1 |
|
|
1864 | #include "ev.c" |
|
|
1865 | |
|
|
1866 | </pre> |
|
|
1867 | <p>This will automatically include <cite>ev.h</cite>, too, and should be done in a |
|
|
1868 | single C source file only to provide the function implementations. To use |
|
|
1869 | it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best |
|
|
1870 | done by writing a wrapper around <cite>ev.h</cite> that you can include instead and |
|
|
1871 | where you can put other configuration options):</p> |
|
|
1872 | <pre> #define EV_STANDALONE 1 |
|
|
1873 | #include "ev.h" |
|
|
1874 | |
|
|
1875 | </pre> |
|
|
1876 | <p>Both header files and implementation files can be compiled with a C++ |
|
|
1877 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1878 | as a bug).</p> |
|
|
1879 | <p>You need the following files in your source tree, or in a directory |
|
|
1880 | in your include path (e.g. in libev/ when using -Ilibev):</p> |
|
|
1881 | <pre> ev.h |
|
|
1882 | ev.c |
|
|
1883 | ev_vars.h |
|
|
1884 | ev_wrap.h |
|
|
1885 | |
|
|
1886 | ev_win32.c required on win32 platforms only |
|
|
1887 | |
|
|
1888 | ev_select.c only when select backend is enabled (which is by default) |
|
|
1889 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1890 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1891 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1892 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1893 | |
|
|
1894 | </pre> |
|
|
1895 | <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need |
|
|
1896 | to compile this single file.</p> |
|
|
1897 | |
|
|
1898 | </div> |
|
|
1899 | <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> |
|
|
1900 | <div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> |
|
|
1901 | <p>To include the libevent compatibility API, also include:</p> |
|
|
1902 | <pre> #include "event.c" |
|
|
1903 | |
|
|
1904 | </pre> |
|
|
1905 | <p>in the file including <cite>ev.c</cite>, and:</p> |
|
|
1906 | <pre> #include "event.h" |
|
|
1907 | |
|
|
1908 | </pre> |
|
|
1909 | <p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p> |
|
|
1910 | <p>You need the following additional files for this:</p> |
|
|
1911 | <pre> event.h |
|
|
1912 | event.c |
|
|
1913 | |
|
|
1914 | </pre> |
|
|
1915 | |
|
|
1916 | </div> |
|
|
1917 | <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> |
|
|
1918 | <div id="AUTOCONF_SUPPORT_CONTENT"> |
|
|
1919 | <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in |
|
|
1920 | whatever way you want, you can also <code>m4_include([libev.m4])</code> in your |
|
|
1921 | <cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then |
|
|
1922 | include <cite>config.h</cite> and configure itself accordingly.</p> |
|
|
1923 | <p>For this of course you need the m4 file:</p> |
|
|
1924 | <pre> libev.m4 |
|
|
1925 | |
|
|
1926 | </pre> |
|
|
1927 | |
|
|
1928 | </div> |
|
|
1929 | <h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2> |
|
|
1930 | <div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT"> |
|
|
1931 | <p>Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1932 | before including any of its files. The default is not to build for multiplicity |
|
|
1933 | and only include the select backend.</p> |
|
|
1934 | <dl> |
|
|
1935 | <dt>EV_STANDALONE</dt> |
|
|
1936 | <dd> |
|
|
1937 | <p>Must always be <code>1</code> if you do not use autoconf configuration, which |
|
|
1938 | keeps libev from including <cite>config.h</cite>, and it also defines dummy |
|
|
1939 | implementations for some libevent functions (such as logging, which is not |
|
|
1940 | supported). It will also not define any of the structs usually found in |
|
|
1941 | <cite>event.h</cite> that are not directly supported by the libev core alone.</p> |
|
|
1942 | </dd> |
|
|
1943 | <dt>EV_USE_MONOTONIC</dt> |
|
|
1944 | <dd> |
|
|
1945 | <p>If defined to be <code>1</code>, libev will try to detect the availability of the |
|
|
1946 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1947 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1948 | usually have to link against librt or something similar. Enabling it when |
|
|
1949 | the functionality isn't available is safe, though, althoguh you have |
|
|
1950 | to make sure you link against any libraries where the <code>clock_gettime</code> |
|
|
1951 | function is hiding in (often <cite>-lrt</cite>).</p> |
|
|
1952 | </dd> |
|
|
1953 | <dt>EV_USE_REALTIME</dt> |
|
|
1954 | <dd> |
|
|
1955 | <p>If defined to be <code>1</code>, libev will try to detect the availability of the |
|
|
1956 | realtime clock option at compiletime (and assume its availability at |
|
|
1957 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1958 | be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get |
|
|
1959 | (CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries |
|
|
1960 | in the description of <code>EV_USE_MONOTONIC</code>, though.</p> |
|
|
1961 | </dd> |
|
|
1962 | <dt>EV_USE_SELECT</dt> |
|
|
1963 | <dd> |
|
|
1964 | <p>If undefined or defined to be <code>1</code>, libev will compile in support for the |
|
|
1965 | <code>select</code>(2) backend. No attempt at autodetection will be done: if no |
|
|
1966 | other method takes over, select will be it. Otherwise the select backend |
|
|
1967 | will not be compiled in.</p> |
|
|
1968 | </dd> |
|
|
1969 | <dt>EV_SELECT_USE_FD_SET</dt> |
|
|
1970 | <dd> |
|
|
1971 | <p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code> |
|
|
1972 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1973 | <code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on |
|
|
1974 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1975 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1976 | allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might |
|
|
1977 | influence the size of the <code>fd_set</code> used.</p> |
|
|
1978 | </dd> |
|
|
1979 | <dt>EV_SELECT_IS_WINSOCKET</dt> |
|
|
1980 | <dd> |
|
|
1981 | <p>When defined to <code>1</code>, the select backend will assume that |
|
|
1982 | select/socket/connect etc. don't understand file descriptors but |
|
|
1983 | wants osf handles on win32 (this is the case when the select to |
|
|
1984 | be used is the winsock select). This means that it will call |
|
|
1985 | <code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise, |
|
|
1986 | it is assumed that all these functions actually work on fds, even |
|
|
1987 | on win32. Should not be defined on non-win32 platforms.</p> |
|
|
1988 | </dd> |
|
|
1989 | <dt>EV_USE_POLL</dt> |
|
|
1990 | <dd> |
|
|
1991 | <p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2) |
|
|
1992 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1993 | takes precedence over select.</p> |
|
|
1994 | </dd> |
|
|
1995 | <dt>EV_USE_EPOLL</dt> |
|
|
1996 | <dd> |
|
|
1997 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux |
|
|
1998 | <code>epoll</code>(7) backend. Its availability will be detected at runtime, |
|
|
1999 | otherwise another method will be used as fallback. This is the |
|
|
2000 | preferred backend for GNU/Linux systems.</p> |
|
|
2001 | </dd> |
|
|
2002 | <dt>EV_USE_KQUEUE</dt> |
|
|
2003 | <dd> |
|
|
2004 | <p>If defined to be <code>1</code>, libev will compile in support for the BSD style |
|
|
2005 | <code>kqueue</code>(2) backend. Its actual availability will be detected at runtime, |
|
|
2006 | otherwise another method will be used as fallback. This is the preferred |
|
|
2007 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
2008 | supports some types of fds correctly (the only platform we found that |
|
|
2009 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
2010 | not be used unless explicitly requested. The best way to use it is to find |
|
|
2011 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
2012 | kqueue loop.</p> |
|
|
2013 | </dd> |
|
|
2014 | <dt>EV_USE_PORT</dt> |
|
|
2015 | <dd> |
|
|
2016 | <p>If defined to be <code>1</code>, libev will compile in support for the Solaris |
|
|
2017 | 10 port style backend. Its availability will be detected at runtime, |
|
|
2018 | otherwise another method will be used as fallback. This is the preferred |
|
|
2019 | backend for Solaris 10 systems.</p> |
|
|
2020 | </dd> |
|
|
2021 | <dt>EV_USE_DEVPOLL</dt> |
|
|
2022 | <dd> |
|
|
2023 | <p>reserved for future expansion, works like the USE symbols above.</p> |
|
|
2024 | </dd> |
|
|
2025 | <dt>EV_USE_INOTIFY</dt> |
|
|
2026 | <dd> |
|
|
2027 | <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify |
|
|
2028 | interface to speed up <code>ev_stat</code> watchers. Its actual availability will |
|
|
2029 | be detected at runtime.</p> |
|
|
2030 | </dd> |
|
|
2031 | <dt>EV_H</dt> |
|
|
2032 | <dd> |
|
|
2033 | <p>The name of the <cite>ev.h</cite> header file used to include it. The default if |
|
|
2034 | undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This |
|
|
2035 | can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> |
|
|
2036 | </dd> |
|
|
2037 | <dt>EV_CONFIG_H</dt> |
|
|
2038 | <dd> |
|
|
2039 | <p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override |
|
|
2040 | <cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to |
|
|
2041 | <code>EV_H</code>, above.</p> |
|
|
2042 | </dd> |
|
|
2043 | <dt>EV_EVENT_H</dt> |
|
|
2044 | <dd> |
|
|
2045 | <p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea |
|
|
2046 | of how the <cite>event.h</cite> header can be found.</p> |
|
|
2047 | </dd> |
|
|
2048 | <dt>EV_PROTOTYPES</dt> |
|
|
2049 | <dd> |
|
|
2050 | <p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function |
|
|
2051 | prototypes, but still define all the structs and other symbols. This is |
|
|
2052 | occasionally useful if you want to provide your own wrapper functions |
|
|
2053 | around libev functions.</p> |
|
|
2054 | </dd> |
|
|
2055 | <dt>EV_MULTIPLICITY</dt> |
|
|
2056 | <dd> |
|
|
2057 | <p>If undefined or defined to <code>1</code>, then all event-loop-specific functions |
|
|
2058 | will have the <code>struct ev_loop *</code> as first argument, and you can create |
|
|
2059 | additional independent event loops. Otherwise there will be no support |
|
|
2060 | for multiple event loops and there is no first event loop pointer |
|
|
2061 | argument. Instead, all functions act on the single default loop.</p> |
|
|
2062 | </dd> |
|
|
2063 | <dt>EV_PERIODIC_ENABLE</dt> |
|
|
2064 | <dd> |
|
|
2065 | <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If |
|
|
2066 | defined to be <code>0</code>, then they are not. Disabling them saves a few kB of |
|
|
2067 | code.</p> |
|
|
2068 | </dd> |
|
|
2069 | <dt>EV_EMBED_ENABLE</dt> |
|
|
2070 | <dd> |
|
|
2071 | <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If |
|
|
2072 | defined to be <code>0</code>, then they are not.</p> |
|
|
2073 | </dd> |
|
|
2074 | <dt>EV_STAT_ENABLE</dt> |
|
|
2075 | <dd> |
|
|
2076 | <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If |
|
|
2077 | defined to be <code>0</code>, then they are not.</p> |
|
|
2078 | </dd> |
|
|
2079 | <dt>EV_FORK_ENABLE</dt> |
|
|
2080 | <dd> |
|
|
2081 | <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If |
|
|
2082 | defined to be <code>0</code>, then they are not.</p> |
|
|
2083 | </dd> |
|
|
2084 | <dt>EV_MINIMAL</dt> |
|
|
2085 | <dd> |
|
|
2086 | <p>If you need to shave off some kilobytes of code at the expense of some |
|
|
2087 | speed, define this symbol to <code>1</code>. Currently only used for gcc to override |
|
|
2088 | some inlining decisions, saves roughly 30% codesize of amd64.</p> |
|
|
2089 | </dd> |
|
|
2090 | <dt>EV_PID_HASHSIZE</dt> |
|
|
2091 | <dd> |
|
|
2092 | <p><code>ev_child</code> watchers use a small hash table to distribute workload by |
|
|
2093 | pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more |
|
|
2094 | than enough. If you need to manage thousands of children you might want to |
|
|
2095 | increase this value (<i>must</i> be a power of two).</p> |
|
|
2096 | </dd> |
|
|
2097 | <dt>EV_INOTIFY_HASHSIZE</dt> |
|
|
2098 | <dd> |
|
|
2099 | <p><code>ev_staz</code> watchers use a small hash table to distribute workload by |
|
|
2100 | inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), |
|
|
2101 | usually more than enough. If you need to manage thousands of <code>ev_stat</code> |
|
|
2102 | watchers you might want to increase this value (<i>must</i> be a power of |
|
|
2103 | two).</p> |
|
|
2104 | </dd> |
|
|
2105 | <dt>EV_COMMON</dt> |
|
|
2106 | <dd> |
|
|
2107 | <p>By default, all watchers have a <code>void *data</code> member. By redefining |
|
|
2108 | this macro to a something else you can include more and other types of |
|
|
2109 | members. You have to define it each time you include one of the files, |
|
|
2110 | though, and it must be identical each time.</p> |
|
|
2111 | <p>For example, the perl EV module uses something like this:</p> |
|
|
2112 | <pre> #define EV_COMMON \ |
|
|
2113 | SV *self; /* contains this struct */ \ |
|
|
2114 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2115 | |
|
|
2116 | </pre> |
|
|
2117 | </dd> |
|
|
2118 | <dt>EV_CB_DECLARE (type)</dt> |
|
|
2119 | <dt>EV_CB_INVOKE (watcher, revents)</dt> |
|
|
2120 | <dt>ev_set_cb (ev, cb)</dt> |
|
|
2121 | <dd> |
|
|
2122 | <p>Can be used to change the callback member declaration in each watcher, |
|
|
2123 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2124 | definition and a statement, respectively. See the <cite>ev.v</cite> header file for |
|
|
2125 | their default definitions. One possible use for overriding these is to |
|
|
2126 | avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use |
|
|
2127 | method calls instead of plain function calls in C++.</p> |
|
|
2128 | |
|
|
2129 | </div> |
|
|
2130 | <h2 id="EXAMPLES">EXAMPLES</h2> |
|
|
2131 | <div id="EXAMPLES_CONTENT"> |
|
|
2132 | <p>For a real-world example of a program the includes libev |
|
|
2133 | verbatim, you can have a look at the EV perl module |
|
|
2134 | (<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in |
|
|
2135 | the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public |
|
|
2136 | interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file |
|
|
2137 | will be compiled. It is pretty complex because it provides its own header |
|
|
2138 | file.</p> |
|
|
2139 | <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file |
|
|
2140 | that everybody includes and which overrides some autoconf choices:</p> |
|
|
2141 | <pre> #define EV_USE_POLL 0 |
|
|
2142 | #define EV_MULTIPLICITY 0 |
|
|
2143 | #define EV_PERIODICS 0 |
|
|
2144 | #define EV_CONFIG_H <config.h> |
|
|
2145 | |
|
|
2146 | #include "ev++.h" |
|
|
2147 | |
|
|
2148 | </pre> |
|
|
2149 | <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> |
|
|
2150 | <pre> #include "ev_cpp.h" |
|
|
2151 | #include "ev.c" |
|
|
2152 | |
|
|
2153 | |
|
|
2154 | |
|
|
2155 | |
|
|
2156 | </pre> |
|
|
2157 | |
|
|
2158 | </div> |
|
|
2159 | <h1 id="COMPLEXITIES">COMPLEXITIES</h1> |
|
|
2160 | <div id="COMPLEXITIES_CONTENT"> |
|
|
2161 | <p>In this section the complexities of (many of) the algorithms used inside |
|
|
2162 | libev will be explained. For complexity discussions about backends see the |
|
|
2163 | documentation for <code>ev_default_init</code>.</p> |
|
|
2164 | <p> |
|
|
2165 | <dl> |
|
|
2166 | <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> |
|
|
2167 | <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> |
|
|
2168 | <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> |
|
|
2169 | <dt>Stopping check/prepare/idle watchers: O(1)</dt> |
|
|
2170 | <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt> |
|
|
2171 | <dt>Finding the next timer per loop iteration: O(1)</dt> |
|
|
2172 | <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> |
|
|
2173 | <dt>Activating one watcher: O(1)</dt> |
|
|
2174 | </dl> |
|
|
2175 | </p> |
|
|
2176 | |
|
|
2177 | |
|
|
2178 | |
|
|
2179 | |
|
|
2180 | |
|
|
2181 | </div> |
|
|
2182 | <h1 id="AUTHOR">AUTHOR</h1> |
1135 | <div id="AUTHOR_CONTENT"> |
2183 | <div id="AUTHOR_CONTENT"> |
1136 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
2184 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1137 | |
2185 | |
1138 | </div> |
2186 | </div> |
1139 | </div></body> |
2187 | </div></body> |
1140 | </html> |
2188 | </html> |