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4 | <head> |
4 | <head> |
5 | <title>libev</title> |
5 | <title>libev</title> |
6 | <meta name="description" content="Pod documentation for libev" /> |
6 | <meta name="description" content="Pod documentation for libev" /> |
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9 | <meta name="created" content="Mon Nov 12 09:02:48 2007" /> |
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12 | <body> |
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13 | <div class="pod"> |
13 | <div class="pod"> |
14 | <!-- INDEX START --> |
14 | <!-- INDEX START --> |
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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="#DESCRIPTION">DESCRIPTION</a></li> |
19 | <li><a href="#DESCRIPTION">DESCRIPTION</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
20 | <li><a href="#FEATURES">FEATURES</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
21 | <li><a href="#CONVENTIONS">CONVENTIONS</a></li> |
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22 | <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> |
22 | <li><a href="#TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> |
23 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
24 | <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> |
24 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
25 | <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> |
25 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | </ul> |
27 | </ul> |
27 | </li> |
28 | </li> |
28 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
29 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
29 | <ul><li><a href="#struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</a></li> |
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> |
30 | <li><a href="#struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</a></li> |
31 | <li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> |
31 | <li><a href="#ev_periodic">ev_periodic</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> |
32 | <li><a href="#ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</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> |
33 | <li><a href="#ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</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> |
34 | <li><a href="#ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</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> |
35 | <li><a href="#prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</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> |
36 | </ul> |
37 | </ul> |
37 | </li> |
38 | </li> |
38 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
39 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
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40 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
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41 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
39 | <li><a href="#AUTHOR">AUTHOR</a> |
42 | <li><a href="#AUTHOR">AUTHOR</a> |
40 | </li> |
43 | </li> |
41 | </ul><hr /> |
44 | </ul><hr /> |
42 | <!-- INDEX END --> |
45 | <!-- INDEX END --> |
43 | |
46 | |
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55 | </div> |
58 | </div> |
56 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
59 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
57 | <div id="DESCRIPTION_CONTENT"> |
60 | <div id="DESCRIPTION_CONTENT"> |
58 | <p>Libev is an event loop: you register interest in certain events (such as a |
61 | <p>Libev is an event loop: you register interest in certain events (such as a |
59 | file descriptor being readable or a timeout occuring), and it will manage |
62 | file descriptor being readable or a timeout occuring), and it will manage |
60 | these event sources and provide your program events.</p> |
63 | these event sources and provide your program with events.</p> |
61 | <p>To do this, it must take more or less complete control over your process |
64 | <p>To do this, it must take more or less complete control over your process |
62 | (or thread) by executing the <i>event loop</i> handler, and will then |
65 | (or thread) by executing the <i>event loop</i> handler, and will then |
63 | communicate events via a callback mechanism.</p> |
66 | communicate events via a callback mechanism.</p> |
64 | <p>You register interest in certain events by registering so-called <i>event |
67 | <p>You register interest in certain events by registering so-called <i>event |
65 | watchers</i>, which are relatively small C structures you initialise with the |
68 | watchers</i>, which are relatively small C structures you initialise with the |
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71 | <div id="FEATURES_CONTENT"> |
74 | <div id="FEATURES_CONTENT"> |
72 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
75 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
73 | kqueue mechanisms for file descriptor events, relative timers, absolute |
76 | kqueue mechanisms for file descriptor events, relative timers, absolute |
74 | timers with customised rescheduling, signal events, process status change |
77 | timers with customised rescheduling, signal events, process status change |
75 | events (related to SIGCHLD), and event watchers dealing with the event |
78 | events (related to SIGCHLD), and event watchers dealing with the event |
76 | loop mechanism itself (idle, prepare and check watchers).</p> |
79 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
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80 | fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing |
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81 | it to libevent for example).</p> |
77 | |
82 | |
78 | </div> |
83 | </div> |
79 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
84 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
80 | <div id="CONVENTIONS_CONTENT"> |
85 | <div id="CONVENTIONS_CONTENT"> |
81 | <p>Libev is very configurable. In this manual the default configuration |
86 | <p>Libev is very configurable. In this manual the default configuration |
82 | will be described, which supports multiple event loops. For more info |
87 | will be described, which supports multiple event loops. For more info |
83 | about various configuraiton options please have a look at the file |
88 | about various configuration options please have a look at the file |
84 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
89 | <cite>README.embed</cite> in the libev distribution. If libev was configured without |
85 | support for multiple event loops, then all functions taking an initial |
90 | support for multiple event loops, then all functions taking an initial |
86 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
91 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
87 | will not have this argument.</p> |
92 | will not have this argument.</p> |
88 | |
93 | |
89 | </div> |
94 | </div> |
90 | <h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
95 | <h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
91 | <div id="TIME_AND_OTHER_GLOBAL_FUNCTIONS_CONT"> |
96 | <div id="TIME_REPRESENTATION_CONTENT"> |
92 | <p>Libev represents time as a single floating point number, representing the |
97 | <p>Libev represents time as a single floating point number, representing the |
93 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
98 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
94 | the beginning of 1970, details are complicated, don't ask). This type is |
99 | the beginning of 1970, details are complicated, don't ask). This type is |
95 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
100 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
96 | to the double type in C.</p> |
101 | to the double type in C.</p> |
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102 | |
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103 | </div> |
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104 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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105 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
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106 | <p>These functions can be called anytime, even before initialising the |
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107 | library in any way.</p> |
97 | <dl> |
108 | <dl> |
98 | <dt>ev_tstamp ev_time ()</dt> |
109 | <dt>ev_tstamp ev_time ()</dt> |
99 | <dd> |
110 | <dd> |
100 | <p>Returns the current time as libev would use it.</p> |
111 | <p>Returns the current time as libev would use it. Please note that the |
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112 | <code>ev_now</code> function is usually faster and also often returns the timestamp |
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113 | you actually want to know.</p> |
101 | </dd> |
114 | </dd> |
102 | <dt>int ev_version_major ()</dt> |
115 | <dt>int ev_version_major ()</dt> |
103 | <dt>int ev_version_minor ()</dt> |
116 | <dt>int ev_version_minor ()</dt> |
104 | <dd> |
117 | <dd> |
105 | <p>You can find out the major and minor version numbers of the library |
118 | <p>You can find out the major and minor version numbers of the library |
106 | you linked against by calling the functions <code>ev_version_major</code> and |
119 | you linked against by calling the functions <code>ev_version_major</code> and |
107 | <code>ev_version_minor</code>. If you want, you can compare against the global |
120 | <code>ev_version_minor</code>. If you want, you can compare against the global |
108 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
121 | symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the |
109 | version of the library your program was compiled against.</p> |
122 | version of the library your program was compiled against.</p> |
110 | <p>Usually, its a good idea to terminate if the major versions mismatch, |
123 | <p>Usually, it's a good idea to terminate if the major versions mismatch, |
111 | as this indicates an incompatible change. Minor versions are usually |
124 | as this indicates an incompatible change. Minor versions are usually |
112 | compatible to older versions, so a larger minor version alone is usually |
125 | compatible to older versions, so a larger minor version alone is usually |
113 | not a problem.</p> |
126 | not a problem.</p> |
114 | </dd> |
127 | </dd> |
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128 | <dt>unsigned int ev_supported_backends ()</dt> |
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129 | <dd> |
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130 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
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131 | value) compiled into this binary of libev (independent of their |
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132 | availability on the system you are running on). See <code>ev_default_loop</code> for |
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133 | a description of the set values.</p> |
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134 | </dd> |
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135 | <dt>unsigned int ev_recommended_backends ()</dt> |
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136 | <dd> |
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137 | <p>Return the set of all backends compiled into this binary of libev and also |
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138 | recommended for this platform. This set is often smaller than the one |
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139 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
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140 | most BSDs and will not be autodetected unless you explicitly request it |
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141 | (assuming you know what you are doing). This is the set of backends that |
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142 | <code>EVFLAG_AUTO</code> will probe for.</p> |
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143 | </dd> |
115 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
144 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
116 | <dd> |
145 | <dd> |
117 | <p>Sets the allocation function to use (the prototype is similar to the |
146 | <p>Sets the allocation function to use (the prototype is similar to the |
118 | realloc function). It is used to allocate and free memory (no surprises |
147 | realloc C function, the semantics are identical). It is used to allocate |
119 | here). If it returns zero when memory needs to be allocated, the library |
148 | and free memory (no surprises here). If it returns zero when memory |
120 | might abort or take some potentially destructive action. The default is |
149 | needs to be allocated, the library might abort or take some potentially |
121 | your system realloc function.</p> |
150 | destructive action. The default is your system realloc function.</p> |
122 | <p>You could override this function in high-availability programs to, say, |
151 | <p>You could override this function in high-availability programs to, say, |
123 | free some memory if it cannot allocate memory, to use a special allocator, |
152 | free some memory if it cannot allocate memory, to use a special allocator, |
124 | or even to sleep a while and retry until some memory is available.</p> |
153 | or even to sleep a while and retry until some memory is available.</p> |
125 | </dd> |
154 | </dd> |
126 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
155 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
127 | <dd> |
156 | <dd> |
128 | <p>Set the callback function to call on a retryable syscall error (such |
157 | <p>Set the callback function to call on a retryable syscall error (such |
129 | as failed select, poll, epoll_wait). The message is a printable string |
158 | as failed select, poll, epoll_wait). The message is a printable string |
130 | indicating the system call or subsystem causing the problem. If this |
159 | indicating the system call or subsystem causing the problem. If this |
131 | callback is set, then libev will expect it to remedy the sitution, no |
160 | callback is set, then libev will expect it to remedy the sitution, no |
132 | matter what, when it returns. That is, libev will geenrally retry the |
161 | matter what, when it returns. That is, libev will generally retry the |
133 | requested operation, or, if the condition doesn't go away, do bad stuff |
162 | requested operation, or, if the condition doesn't go away, do bad stuff |
134 | (such as abort).</p> |
163 | (such as abort).</p> |
135 | </dd> |
164 | </dd> |
136 | </dl> |
165 | </dl> |
137 | |
166 | |
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140 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
169 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
141 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
170 | <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two |
142 | types of such loops, the <i>default</i> loop, which supports signals and child |
171 | types of such loops, the <i>default</i> loop, which supports signals and child |
143 | events, and dynamically created loops which do not.</p> |
172 | events, and dynamically created loops which do not.</p> |
144 | <p>If you use threads, a common model is to run the default event loop |
173 | <p>If you use threads, a common model is to run the default event loop |
145 | in your main thread (or in a separate thrad) and for each thread you |
174 | in your main thread (or in a separate thread) and for each thread you |
146 | create, you also create another event loop. Libev itself does no lockign |
175 | create, you also create another event loop. Libev itself does no locking |
147 | whatsoever, so if you mix calls to different event loops, make sure you |
176 | whatsoever, so if you mix calls to the same event loop in different |
148 | lock (this is usually a bad idea, though, even if done right).</p> |
177 | threads, make sure you lock (this is usually a bad idea, though, even if |
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178 | done correctly, because it's hideous and inefficient).</p> |
149 | <dl> |
179 | <dl> |
150 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
180 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
151 | <dd> |
181 | <dd> |
152 | <p>This will initialise the default event loop if it hasn't been initialised |
182 | <p>This will initialise the default event loop if it hasn't been initialised |
153 | yet and return it. If the default loop could not be initialised, returns |
183 | yet and return it. If the default loop could not be initialised, returns |
154 | false. If it already was initialised it simply returns it (and ignores the |
184 | false. If it already was initialised it simply returns it (and ignores the |
155 | flags).</p> |
185 | flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p> |
156 | <p>If you don't know what event loop to use, use the one returned from this |
186 | <p>If you don't know what event loop to use, use the one returned from this |
157 | function.</p> |
187 | function.</p> |
158 | <p>The flags argument can be used to specify special behaviour or specific |
188 | <p>The flags argument can be used to specify special behaviour or specific |
159 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO)</p> |
189 | backends to use, and is usually specified as <code>0</code> (or EVFLAG_AUTO).</p> |
160 | <p>It supports the following flags:</p> |
190 | <p>It supports the following flags:</p> |
161 | <p> |
191 | <p> |
162 | <dl> |
192 | <dl> |
163 | <dt>EVFLAG_AUTO</dt> |
193 | <dt><code>EVFLAG_AUTO</code></dt> |
164 | <dd> |
194 | <dd> |
165 | <p>The default flags value. Use this if you have no clue (its the right |
195 | <p>The default flags value. Use this if you have no clue (it's the right |
166 | thing, believe me).</p> |
196 | thing, believe me).</p> |
167 | </dd> |
197 | </dd> |
168 | <dt>EVFLAG_NOENV</dt> |
198 | <dt><code>EVFLAG_NOENV</code></dt> |
169 | <dd> |
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170 | <p>If this flag bit is ored into the flag value then libev will <i>not</i> look |
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171 | at the environment variable <code>LIBEV_FLAGS</code>. Otherwise (the default), this |
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172 | environment variable will override the flags completely. This is useful |
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173 | to try out specific backends to tets their performance, or to work around |
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174 | bugs.</p> |
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175 | </dd> |
199 | <dd> |
176 | <dt>EVMETHOD_SELECT portable select backend</dt> |
200 | <p>If this flag bit is ored into the flag value (or the program runs setuid |
177 | <dt>EVMETHOD_POLL poll backend (everywhere except windows)</dt> |
201 | or setgid) then libev will <i>not</i> look at the environment variable |
178 | <dt>EVMETHOD_EPOLL linux only</dt> |
202 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
179 | <dt>EVMETHOD_KQUEUE some bsds only</dt> |
203 | override the flags completely if it is found in the environment. This is |
180 | <dt>EVMETHOD_DEVPOLL solaris 8 only</dt> |
204 | useful to try out specific backends to test their performance, or to work |
181 | <dt>EVMETHOD_PORT solaris 10 only</dt> |
205 | around bugs.</p> |
182 | <dd> |
206 | </dd> |
183 | <p>If one or more of these are ored into the flags value, then only these |
207 | <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> |
184 | backends will be tried (in the reverse order as given here). If one are |
208 | <dd> |
185 | specified, any backend will do.</p> |
209 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
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210 | libev tries to roll its own fd_set with no limits on the number of fds, |
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211 | but if that fails, expect a fairly low limit on the number of fds when |
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212 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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213 | the fastest backend for a low number of fds.</p> |
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214 | </dd> |
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215 | <dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
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216 | <dd> |
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217 | <p>And this is your standard poll(2) backend. It's more complicated than |
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218 | select, but handles sparse fds better and has no artificial limit on the |
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219 | number of fds you can use (except it will slow down considerably with a |
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220 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
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221 | </dd> |
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222 | <dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt> |
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223 | <dd> |
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224 | <p>For few fds, this backend is a bit little slower than poll and select, |
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225 | but it scales phenomenally better. While poll and select usually scale like |
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226 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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227 | either O(1) or O(active_fds).</p> |
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228 | <p>While stopping and starting an I/O watcher in the same iteration will |
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229 | result in some caching, there is still a syscall per such incident |
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230 | (because the fd could point to a different file description now), so its |
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231 | best to avoid that. Also, dup()ed file descriptors might not work very |
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232 | well if you register events for both fds.</p> |
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233 | </dd> |
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234 | <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> |
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235 | <dd> |
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236 | <p>Kqueue deserves special mention, as at the time of this writing, it |
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237 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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238 | anything but sockets and pipes, except on Darwin, where of course its |
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239 | completely useless). For this reason its not being "autodetected" unless |
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240 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).</p> |
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241 | <p>It scales in the same way as the epoll backend, but the interface to the |
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242 | kernel is more efficient (which says nothing about its actual speed, of |
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243 | course). While starting and stopping an I/O watcher does not cause an |
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244 | extra syscall as with epoll, it still adds up to four event changes per |
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245 | incident, so its best to avoid that.</p> |
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246 | </dd> |
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247 | <dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt> |
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248 | <dd> |
|
|
249 | <p>This is not implemented yet (and might never be).</p> |
|
|
250 | </dd> |
|
|
251 | <dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt> |
|
|
252 | <dd> |
|
|
253 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
|
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254 | it's really slow, but it still scales very well (O(active_fds)).</p> |
|
|
255 | </dd> |
|
|
256 | <dt><code>EVBACKEND_ALL</code></dt> |
|
|
257 | <dd> |
|
|
258 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
|
|
259 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
|
|
260 | <code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p> |
186 | </dd> |
261 | </dd> |
187 | </dl> |
262 | </dl> |
188 | </p> |
263 | </p> |
|
|
264 | <p>If one or more of these are ored into the flags value, then only these |
|
|
265 | backends will be tried (in the reverse order as given here). If none are |
|
|
266 | specified, most compiled-in backend will be tried, usually in reverse |
|
|
267 | order of their flag values :)</p> |
189 | </dd> |
268 | </dd> |
190 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
269 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
191 | <dd> |
270 | <dd> |
192 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
271 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
193 | always distinct from the default loop. Unlike the default loop, it cannot |
272 | always distinct from the default loop. Unlike the default loop, it cannot |
… | |
… | |
196 | </dd> |
275 | </dd> |
197 | <dt>ev_default_destroy ()</dt> |
276 | <dt>ev_default_destroy ()</dt> |
198 | <dd> |
277 | <dd> |
199 | <p>Destroys the default loop again (frees all memory and kernel state |
278 | <p>Destroys the default loop again (frees all memory and kernel state |
200 | etc.). This stops all registered event watchers (by not touching them in |
279 | etc.). This stops all registered event watchers (by not touching them in |
201 | any way whatsoever, although you cnanot rely on this :).</p> |
280 | any way whatsoever, although you cannot rely on this :).</p> |
202 | </dd> |
281 | </dd> |
203 | <dt>ev_loop_destroy (loop)</dt> |
282 | <dt>ev_loop_destroy (loop)</dt> |
204 | <dd> |
283 | <dd> |
205 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
284 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
206 | earlier call to <code>ev_loop_new</code>.</p> |
285 | earlier call to <code>ev_loop_new</code>.</p> |
… | |
… | |
209 | <dd> |
288 | <dd> |
210 | <p>This function reinitialises the kernel state for backends that have |
289 | <p>This function reinitialises the kernel state for backends that have |
211 | one. Despite the name, you can call it anytime, but it makes most sense |
290 | one. Despite the name, you can call it anytime, but it makes most sense |
212 | after forking, in either the parent or child process (or both, but that |
291 | after forking, in either the parent or child process (or both, but that |
213 | again makes little sense).</p> |
292 | again makes little sense).</p> |
214 | <p>You <i>must</i> call this function after forking if and only if you want to |
293 | <p>You <i>must</i> call this function in the child process after forking if and |
215 | use the event library in both processes. If you just fork+exec, you don't |
294 | only if you want to use the event library in both processes. If you just |
216 | have to call it.</p> |
295 | fork+exec, you don't have to call it.</p> |
217 | <p>The function itself is quite fast and its usually not a problem to call |
296 | <p>The function itself is quite fast and it's usually not a problem to call |
218 | it just in case after a fork. To make this easy, the function will fit in |
297 | it just in case after a fork. To make this easy, the function will fit in |
219 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
298 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
220 | <pre> pthread_atfork (0, 0, ev_default_fork); |
299 | <pre> pthread_atfork (0, 0, ev_default_fork); |
221 | |
300 | |
222 | </pre> |
301 | </pre> |
|
|
302 | <p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use |
|
|
303 | without calling this function, so if you force one of those backends you |
|
|
304 | do not need to care.</p> |
223 | </dd> |
305 | </dd> |
224 | <dt>ev_loop_fork (loop)</dt> |
306 | <dt>ev_loop_fork (loop)</dt> |
225 | <dd> |
307 | <dd> |
226 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
308 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
227 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
309 | <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop |
228 | after fork, and how you do this is entirely your own problem.</p> |
310 | after fork, and how you do this is entirely your own problem.</p> |
229 | </dd> |
311 | </dd> |
230 | <dt>unsigned int ev_method (loop)</dt> |
312 | <dt>unsigned int ev_backend (loop)</dt> |
231 | <dd> |
313 | <dd> |
232 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
314 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
233 | use.</p> |
315 | use.</p> |
234 | </dd> |
316 | </dd> |
235 | <dt>ev_tstamp = ev_now (loop)</dt> |
317 | <dt>ev_tstamp ev_now (loop)</dt> |
236 | <dd> |
318 | <dd> |
237 | <p>Returns the current "event loop time", which is the time the event loop |
319 | <p>Returns the current "event loop time", which is the time the event loop |
238 | got events and started processing them. This timestamp does not change |
320 | got events and started processing them. This timestamp does not change |
239 | as long as callbacks are being processed, and this is also the base time |
321 | as long as callbacks are being processed, and this is also the base time |
240 | used for relative timers. You can treat it as the timestamp of the event |
322 | used for relative timers. You can treat it as the timestamp of the event |
… | |
… | |
247 | events.</p> |
329 | events.</p> |
248 | <p>If the flags argument is specified as 0, it will not return until either |
330 | <p>If the flags argument is specified as 0, it will not return until either |
249 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
331 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
250 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
332 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
251 | those events and any outstanding ones, but will not block your process in |
333 | those events and any outstanding ones, but will not block your process in |
252 | case there are no events.</p> |
334 | case there are no events and will return after one iteration of the loop.</p> |
253 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
335 | <p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if |
254 | neccessary) and will handle those and any outstanding ones. It will block |
336 | neccessary) and will handle those and any outstanding ones. It will block |
255 | your process until at least one new event arrives.</p> |
337 | your process until at least one new event arrives, and will return after |
|
|
338 | one iteration of the loop.</p> |
256 | <p>This flags value could be used to implement alternative looping |
339 | <p>This flags value could be used to implement alternative looping |
257 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
340 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
258 | more generic mechanism.</p> |
341 | more generic mechanism.</p> |
|
|
342 | <p>Here are the gory details of what ev_loop does:</p> |
|
|
343 | <pre> 1. If there are no active watchers (reference count is zero), return. |
|
|
344 | 2. Queue and immediately call all prepare watchers. |
|
|
345 | 3. If we have been forked, recreate the kernel state. |
|
|
346 | 4. Update the kernel state with all outstanding changes. |
|
|
347 | 5. Update the "event loop time". |
|
|
348 | 6. Calculate for how long to block. |
|
|
349 | 7. Block the process, waiting for events. |
|
|
350 | 8. Update the "event loop time" and do time jump handling. |
|
|
351 | 9. Queue all outstanding timers. |
|
|
352 | 10. Queue all outstanding periodics. |
|
|
353 | 11. If no events are pending now, queue all idle watchers. |
|
|
354 | 12. Queue all check watchers. |
|
|
355 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
356 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
|
357 | was used, return, otherwise continue with step #1. |
|
|
358 | |
|
|
359 | </pre> |
259 | </dd> |
360 | </dd> |
260 | <dt>ev_unloop (loop, how)</dt> |
361 | <dt>ev_unloop (loop, how)</dt> |
261 | <dd> |
362 | <dd> |
262 | <p>Can be used to make a call to <code>ev_loop</code> return early. The <code>how</code> argument |
363 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
|
|
364 | has processed all outstanding events). The <code>how</code> argument must be either |
263 | must be either <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> |
365 | <code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or |
264 | call return, or <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> |
366 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
265 | calls return.</p> |
|
|
266 | </dd> |
367 | </dd> |
267 | <dt>ev_ref (loop)</dt> |
368 | <dt>ev_ref (loop)</dt> |
268 | <dt>ev_unref (loop)</dt> |
369 | <dt>ev_unref (loop)</dt> |
269 | <dd> |
370 | <dd> |
270 | <p>Ref/unref can be used to add or remove a refcount on the event loop: Every |
371 | <p>Ref/unref can be used to add or remove a reference count on the event |
271 | watcher keeps one reference. If you have a long-runing watcher you never |
372 | loop: Every watcher keeps one reference, and as long as the reference |
272 | unregister that should not keep ev_loop from running, ev_unref() after |
373 | count is nonzero, <code>ev_loop</code> will not return on its own. If you have |
273 | starting, and ev_ref() before stopping it. Libev itself uses this for |
374 | a watcher you never unregister that should not keep <code>ev_loop</code> from |
274 | example for its internal signal pipe: It is not visible to you as a user |
375 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
275 | and should not keep <code>ev_loop</code> from exiting if the work is done. It is |
376 | example, libev itself uses this for its internal signal pipe: It is not |
276 | also an excellent way to do this for generic recurring timers or from |
377 | visible to the libev user and should not keep <code>ev_loop</code> from exiting if |
277 | within third-party libraries. Just remember to unref after start and ref |
378 | no event watchers registered by it are active. It is also an excellent |
278 | before stop.</p> |
379 | way to do this for generic recurring timers or from within third-party |
|
|
380 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
279 | </dd> |
381 | </dd> |
280 | </dl> |
382 | </dl> |
281 | |
383 | |
282 | </div> |
384 | </div> |
283 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
385 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
284 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
386 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
285 | <p>A watcher is a structure that you create and register to record your |
387 | <p>A watcher is a structure that you create and register to record your |
286 | interest in some event. For instance, if you want to wait for STDIN to |
388 | interest in some event. For instance, if you want to wait for STDIN to |
287 | become readable, you would create an ev_io watcher for that:</p> |
389 | become readable, you would create an <code>ev_io</code> watcher for that:</p> |
288 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
390 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
289 | { |
391 | { |
290 | ev_io_stop (w); |
392 | ev_io_stop (w); |
291 | ev_unloop (loop, EVUNLOOP_ALL); |
393 | ev_unloop (loop, EVUNLOOP_ALL); |
292 | } |
394 | } |
… | |
… | |
315 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
417 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
316 | *)</code>), and you can stop watching for events at any time by calling the |
418 | *)</code>), and you can stop watching for events at any time by calling the |
317 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
419 | corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p> |
318 | <p>As long as your watcher is active (has been started but not stopped) you |
420 | <p>As long as your watcher is active (has been started but not stopped) you |
319 | must not touch the values stored in it. Most specifically you must never |
421 | must not touch the values stored in it. Most specifically you must never |
320 | reinitialise it or call its set method.</p> |
422 | reinitialise it or call its set macro.</p> |
321 | <p>You cna check wether an event is active by calling the <code>ev_is_active |
423 | <p>You can check whether an event is active by calling the <code>ev_is_active |
322 | (watcher *)</code> macro. To see wether an event is outstanding (but the |
424 | (watcher *)</code> macro. To see whether an event is outstanding (but the |
323 | callback for it has not been called yet) you cna use the <code>ev_is_pending |
425 | callback for it has not been called yet) you can use the <code>ev_is_pending |
324 | (watcher *)</code> macro.</p> |
426 | (watcher *)</code> macro.</p> |
325 | <p>Each and every callback receives the event loop pointer as first, the |
427 | <p>Each and every callback receives the event loop pointer as first, the |
326 | registered watcher structure as second, and a bitset of received events as |
428 | registered watcher structure as second, and a bitset of received events as |
327 | third argument.</p> |
429 | third argument.</p> |
328 | <p>The rceeived events usually include a single bit per event type received |
430 | <p>The received events usually include a single bit per event type received |
329 | (you can receive multiple events at the same time). The possible bit masks |
431 | (you can receive multiple events at the same time). The possible bit masks |
330 | are:</p> |
432 | are:</p> |
331 | <dl> |
433 | <dl> |
332 | <dt>EV_READ</dt> |
434 | <dt><code>EV_READ</code></dt> |
333 | <dt>EV_WRITE</dt> |
435 | <dt><code>EV_WRITE</code></dt> |
334 | <dd> |
436 | <dd> |
335 | <p>The file descriptor in the ev_io watcher has become readable and/or |
437 | <p>The file descriptor in the <code>ev_io</code> watcher has become readable and/or |
336 | writable.</p> |
438 | writable.</p> |
337 | </dd> |
439 | </dd> |
338 | <dt>EV_TIMEOUT</dt> |
440 | <dt><code>EV_TIMEOUT</code></dt> |
339 | <dd> |
|
|
340 | <p>The ev_timer watcher has timed out.</p> |
|
|
341 | </dd> |
441 | <dd> |
342 | <dt>EV_PERIODIC</dt> |
442 | <p>The <code>ev_timer</code> watcher has timed out.</p> |
343 | <dd> |
443 | </dd> |
344 | <p>The ev_periodic watcher has timed out.</p> |
444 | <dt><code>EV_PERIODIC</code></dt> |
345 | </dd> |
445 | <dd> |
346 | <dt>EV_SIGNAL</dt> |
446 | <p>The <code>ev_periodic</code> watcher has timed out.</p> |
347 | <dd> |
447 | </dd> |
|
|
448 | <dt><code>EV_SIGNAL</code></dt> |
|
|
449 | <dd> |
348 | <p>The signal specified in the ev_signal watcher has been received by a thread.</p> |
450 | <p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p> |
349 | </dd> |
|
|
350 | <dt>EV_CHILD</dt> |
|
|
351 | <dd> |
451 | </dd> |
|
|
452 | <dt><code>EV_CHILD</code></dt> |
|
|
453 | <dd> |
352 | <p>The pid specified in the ev_child watcher has received a status change.</p> |
454 | <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> |
353 | </dd> |
|
|
354 | <dt>EV_IDLE</dt> |
|
|
355 | <dd> |
455 | </dd> |
|
|
456 | <dt><code>EV_IDLE</code></dt> |
|
|
457 | <dd> |
356 | <p>The ev_idle watcher has determined that you have nothing better to do.</p> |
458 | <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> |
357 | </dd> |
|
|
358 | <dt>EV_PREPARE</dt> |
|
|
359 | <dt>EV_CHECK</dt> |
|
|
360 | <dd> |
459 | </dd> |
|
|
460 | <dt><code>EV_PREPARE</code></dt> |
|
|
461 | <dt><code>EV_CHECK</code></dt> |
|
|
462 | <dd> |
361 | <p>All ev_prepare watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
463 | <p>All <code>ev_prepare</code> watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
362 | to gather new events, and all ev_check watchers are invoked just after |
464 | to gather new events, and all <code>ev_check</code> watchers are invoked just after |
363 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
465 | <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any |
364 | received events. Callbacks of both watcher types can start and stop as |
466 | received events. Callbacks of both watcher types can start and stop as |
365 | many watchers as they want, and all of them will be taken into account |
467 | many watchers as they want, and all of them will be taken into account |
366 | (for example, a ev_prepare watcher might start an idle watcher to keep |
468 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
367 | <code>ev_loop</code> from blocking).</p> |
469 | <code>ev_loop</code> from blocking).</p> |
368 | </dd> |
470 | </dd> |
369 | <dt>EV_ERROR</dt> |
471 | <dt><code>EV_ERROR</code></dt> |
370 | <dd> |
472 | <dd> |
371 | <p>An unspecified error has occured, the watcher has been stopped. This might |
473 | <p>An unspecified error has occured, the watcher has been stopped. This might |
372 | happen because the watcher could not be properly started because libev |
474 | happen because the watcher could not be properly started because libev |
373 | ran out of memory, a file descriptor was found to be closed or any other |
475 | ran out of memory, a file descriptor was found to be closed or any other |
374 | problem. You best act on it by reporting the problem and somehow coping |
476 | problem. You best act on it by reporting the problem and somehow coping |
… | |
… | |
383 | |
485 | |
384 | </div> |
486 | </div> |
385 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
487 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
386 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
488 | <div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> |
387 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
489 | <p>Each watcher has, by default, a member <code>void *data</code> that you can change |
388 | and read at any time, libev will completely ignore it. This cna be used |
490 | and read at any time, libev will completely ignore it. This can be used |
389 | to associate arbitrary data with your watcher. If you need more data and |
491 | to associate arbitrary data with your watcher. If you need more data and |
390 | don't want to allocate memory and store a pointer to it in that data |
492 | don't want to allocate memory and store a pointer to it in that data |
391 | member, you can also "subclass" the watcher type and provide your own |
493 | member, you can also "subclass" the watcher type and provide your own |
392 | data:</p> |
494 | data:</p> |
393 | <pre> struct my_io |
495 | <pre> struct my_io |
… | |
… | |
420 | <div id="WATCHER_TYPES_CONTENT"> |
522 | <div id="WATCHER_TYPES_CONTENT"> |
421 | <p>This section describes each watcher in detail, but will not repeat |
523 | <p>This section describes each watcher in detail, but will not repeat |
422 | information given in the last section.</p> |
524 | information given in the last section.</p> |
423 | |
525 | |
424 | </div> |
526 | </div> |
425 | <h2 id="struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</h2> |
527 | <h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> |
426 | <div id="struct_ev_io_is_my_file_descriptor_r-2"> |
528 | <div id="code_ev_io_code_is_this_file_descrip-2"> |
427 | <p>I/O watchers check wether a file descriptor is readable or writable |
529 | <p>I/O watchers check whether a file descriptor is readable or writable |
428 | in each iteration of the event loop (This behaviour is called |
530 | in each iteration of the event loop (This behaviour is called |
429 | level-triggering because you keep receiving events as long as the |
531 | level-triggering because you keep receiving events as long as the |
430 | condition persists. Remember you cna stop the watcher if you don't want to |
532 | condition persists. Remember you can stop the watcher if you don't want to |
431 | act on the event and neither want to receive future events).</p> |
533 | act on the event and neither want to receive future events).</p> |
|
|
534 | <p>In general you can register as many read and/or write event watchers per |
|
|
535 | fd as you want (as long as you don't confuse yourself). Setting all file |
|
|
536 | descriptors to non-blocking mode is also usually a good idea (but not |
|
|
537 | required if you know what you are doing).</p> |
|
|
538 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
539 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
540 | descriptors correctly if you register interest in two or more fds pointing |
|
|
541 | to the same underlying file/socket etc. description (that is, they share |
|
|
542 | the same underlying "file open").</p> |
|
|
543 | <p>If you must do this, then force the use of a known-to-be-good backend |
|
|
544 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
|
|
545 | <code>EVBACKEND_POLL</code>).</p> |
432 | <dl> |
546 | <dl> |
433 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
547 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
434 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
548 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
435 | <dd> |
549 | <dd> |
436 | <p>Configures an ev_io watcher. The fd is the file descriptor to rceeive |
550 | <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive |
437 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
551 | events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | |
438 | EV_WRITE</code> to receive the given events.</p> |
552 | EV_WRITE</code> to receive the given events.</p> |
439 | </dd> |
553 | </dd> |
440 | </dl> |
554 | </dl> |
441 | |
555 | |
442 | </div> |
556 | </div> |
443 | <h2 id="struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</h2> |
557 | <h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> |
444 | <div id="struct_ev_timer_relative_and_optiona-2"> |
558 | <div id="code_ev_timer_code_relative_and_opti-2"> |
445 | <p>Timer watchers are simple relative timers that generate an event after a |
559 | <p>Timer watchers are simple relative timers that generate an event after a |
446 | given time, and optionally repeating in regular intervals after that.</p> |
560 | given time, and optionally repeating in regular intervals after that.</p> |
447 | <p>The timers are based on real time, that is, if you register an event that |
561 | <p>The timers are based on real time, that is, if you register an event that |
448 | times out after an hour and youreset your system clock to last years |
562 | times out after an hour and you reset your system clock to last years |
449 | time, it will still time out after (roughly) and hour. "Roughly" because |
563 | time, it will still time out after (roughly) and hour. "Roughly" because |
450 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
564 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
451 | monotonic clock option helps a lot here).</p> |
565 | monotonic clock option helps a lot here).</p> |
|
|
566 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
|
|
567 | time. This is usually the right thing as this timestamp refers to the time |
|
|
568 | of the event triggering whatever timeout you are modifying/starting. If |
|
|
569 | you suspect event processing to be delayed and you <i>need</i> to base the timeout |
|
|
570 | on the current time, use something like this to adjust for this:</p> |
|
|
571 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
572 | |
|
|
573 | </pre> |
|
|
574 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
575 | but if multiple timers become ready during the same loop iteration then |
|
|
576 | order of execution is undefined.</p> |
452 | <dl> |
577 | <dl> |
453 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
578 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
454 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
579 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
455 | <dd> |
580 | <dd> |
456 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
581 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
… | |
… | |
458 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
583 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
459 | later, again, and again, until stopped manually.</p> |
584 | later, again, and again, until stopped manually.</p> |
460 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
585 | <p>The timer itself will do a best-effort at avoiding drift, that is, if you |
461 | configure a timer to trigger every 10 seconds, then it will trigger at |
586 | configure a timer to trigger every 10 seconds, then it will trigger at |
462 | exactly 10 second intervals. If, however, your program cannot keep up with |
587 | exactly 10 second intervals. If, however, your program cannot keep up with |
463 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
588 | the timer (because it takes longer than those 10 seconds to do stuff) the |
464 | timer will not fire more than once per event loop iteration.</p> |
589 | timer will not fire more than once per event loop iteration.</p> |
465 | </dd> |
590 | </dd> |
466 | <dt>ev_timer_again (loop)</dt> |
591 | <dt>ev_timer_again (loop)</dt> |
467 | <dd> |
592 | <dd> |
468 | <p>This will act as if the timer timed out and restart it again if it is |
593 | <p>This will act as if the timer timed out and restart it again if it is |
… | |
… | |
472 | value), or reset the running timer to the repeat value.</p> |
597 | value), or reset the running timer to the repeat value.</p> |
473 | <p>This sounds a bit complicated, but here is a useful and typical |
598 | <p>This sounds a bit complicated, but here is a useful and typical |
474 | example: Imagine you have a tcp connection and you want a so-called idle |
599 | example: Imagine you have a tcp connection and you want a so-called idle |
475 | timeout, that is, you want to be called when there have been, say, 60 |
600 | timeout, that is, you want to be called when there have been, say, 60 |
476 | seconds of inactivity on the socket. The easiest way to do this is to |
601 | seconds of inactivity on the socket. The easiest way to do this is to |
477 | configure an ev_timer with after=repeat=60 and calling ev_timer_again each |
602 | configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each |
478 | time you successfully read or write some data. If you go into an idle |
603 | time you successfully read or write some data. If you go into an idle |
479 | state where you do not expect data to travel on the socket, you can stop |
604 | state where you do not expect data to travel on the socket, you can stop |
480 | the timer, and again will automatically restart it if need be.</p> |
605 | the timer, and again will automatically restart it if need be.</p> |
481 | </dd> |
606 | </dd> |
482 | </dl> |
607 | </dl> |
483 | |
608 | |
484 | </div> |
609 | </div> |
485 | <h2 id="ev_periodic">ev_periodic</h2> |
610 | <h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> |
486 | <div id="ev_periodic_CONTENT"> |
611 | <div id="code_ev_periodic_code_to_cron_or_not-2"> |
487 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
612 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
488 | (and unfortunately a bit complex).</p> |
613 | (and unfortunately a bit complex).</p> |
489 | <p>Unlike ev_timer's, they are not based on real time (or relative time) |
614 | <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) |
490 | but on wallclock time (absolute time). You can tell a periodic watcher |
615 | but on wallclock time (absolute time). You can tell a periodic watcher |
491 | to trigger "at" some specific point in time. For example, if you tell a |
616 | to trigger "at" some specific point in time. For example, if you tell a |
492 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
617 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
493 | + 10.>) and then reset your system clock to the last year, then it will |
618 | + 10.>) and then reset your system clock to the last year, then it will |
494 | take a year to trigger the event (unlike an ev_timer, which would trigger |
619 | take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger |
495 | roughly 10 seconds later and of course not if you reset your system time |
620 | roughly 10 seconds later and of course not if you reset your system time |
496 | again).</p> |
621 | again).</p> |
497 | <p>They can also be used to implement vastly more complex timers, such as |
622 | <p>They can also be used to implement vastly more complex timers, such as |
498 | triggering an event on eahc midnight, local time.</p> |
623 | triggering an event on eahc midnight, local time.</p> |
|
|
624 | <p>As with timers, the callback is guarenteed to be invoked only when the |
|
|
625 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
|
|
626 | during the same loop iteration then order of execution is undefined.</p> |
499 | <dl> |
627 | <dl> |
500 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
628 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
501 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
629 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
502 | <dd> |
630 | <dd> |
503 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
631 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
504 | operation, and we will explain them from simplest to complex:</p> |
632 | operation, and we will explain them from simplest to complex:</p> |
505 | |
|
|
506 | |
|
|
507 | |
|
|
508 | |
|
|
509 | <p> |
633 | <p> |
510 | <dl> |
634 | <dl> |
511 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
635 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
512 | <dd> |
636 | <dd> |
513 | <p>In this configuration the watcher triggers an event at the wallclock time |
637 | <p>In this configuration the watcher triggers an event at the wallclock time |
… | |
… | |
525 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
649 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
526 | |
650 | |
527 | </pre> |
651 | </pre> |
528 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
652 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
529 | but only that the the callback will be called when the system time shows a |
653 | but only that the the callback will be called when the system time shows a |
530 | full hour (UTC), or more correct, when the system time is evenly divisible |
654 | full hour (UTC), or more correctly, when the system time is evenly divisible |
531 | by 3600.</p> |
655 | by 3600.</p> |
532 | <p>Another way to think about it (for the mathematically inclined) is that |
656 | <p>Another way to think about it (for the mathematically inclined) is that |
533 | ev_periodic will try to run the callback in this mode at the next possible |
657 | <code>ev_periodic</code> will try to run the callback in this mode at the next possible |
534 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
658 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
535 | </dd> |
659 | </dd> |
536 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
660 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
537 | <dd> |
661 | <dd> |
538 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
662 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
539 | ignored. Instead, each time the periodic watcher gets scheduled, the |
663 | ignored. Instead, each time the periodic watcher gets scheduled, the |
540 | reschedule callback will be called with the watcher as first, and the |
664 | reschedule callback will be called with the watcher as first, and the |
541 | current time as second argument.</p> |
665 | current time as second argument.</p> |
542 | <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other |
666 | <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, |
543 | periodic watcher, ever, or make any event loop modificstions</i>. If you need |
667 | ever, or make any event loop modifications</i>. If you need to stop it, |
544 | to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards.</p> |
668 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
669 | starting a prepare watcher).</p> |
545 | <p>Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
670 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
546 | ev_tstamp now)>, e.g.:</p> |
671 | ev_tstamp now)</code>, e.g.:</p> |
547 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
672 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
548 | { |
673 | { |
549 | return now + 60.; |
674 | return now + 60.; |
550 | } |
675 | } |
551 | |
676 | |
552 | </pre> |
677 | </pre> |
553 | <p>It must return the next time to trigger, based on the passed time value |
678 | <p>It must return the next time to trigger, based on the passed time value |
554 | (that is, the lowest time value larger than to the second argument). It |
679 | (that is, the lowest time value larger than to the second argument). It |
555 | will usually be called just before the callback will be triggered, but |
680 | will usually be called just before the callback will be triggered, but |
556 | might be called at other times, too.</p> |
681 | might be called at other times, too.</p> |
|
|
682 | <p>NOTE: <i>This callback must always return a time that is later than the |
|
|
683 | passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p> |
557 | <p>This can be used to create very complex timers, such as a timer that |
684 | <p>This can be used to create very complex timers, such as a timer that |
558 | triggers on each midnight, local time. To do this, you would calculate the |
685 | triggers on each midnight, local time. To do this, you would calculate the |
559 | next midnight after <code>now</code> and return the timestamp value for this. How you do this |
686 | next midnight after <code>now</code> and return the timestamp value for this. How |
560 | is, again, up to you (but it is not trivial).</p> |
687 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
688 | reason I omitted it as an example).</p> |
561 | </dd> |
689 | </dd> |
562 | </dl> |
690 | </dl> |
563 | </p> |
691 | </p> |
564 | </dd> |
692 | </dd> |
565 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
693 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
… | |
… | |
570 | program when the crontabs have changed).</p> |
698 | program when the crontabs have changed).</p> |
571 | </dd> |
699 | </dd> |
572 | </dl> |
700 | </dl> |
573 | |
701 | |
574 | </div> |
702 | </div> |
575 | <h2 id="ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</h2> |
703 | <h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> |
576 | <div id="ev_signal_signal_me_when_a_signal_ge-2"> |
704 | <div id="code_ev_signal_code_signal_me_when_a-2"> |
577 | <p>Signal watchers will trigger an event when the process receives a specific |
705 | <p>Signal watchers will trigger an event when the process receives a specific |
578 | signal one or more times. Even though signals are very asynchronous, libev |
706 | signal one or more times. Even though signals are very asynchronous, libev |
579 | will try its best to deliver signals synchronously, i.e. as part of the |
707 | will try it's best to deliver signals synchronously, i.e. as part of the |
580 | normal event processing, like any other event.</p> |
708 | normal event processing, like any other event.</p> |
581 | <p>You cna configure as many watchers as you like per signal. Only when the |
709 | <p>You can configure as many watchers as you like per signal. Only when the |
582 | first watcher gets started will libev actually register a signal watcher |
710 | first watcher gets started will libev actually register a signal watcher |
583 | with the kernel (thus it coexists with your own signal handlers as long |
711 | with the kernel (thus it coexists with your own signal handlers as long |
584 | as you don't register any with libev). Similarly, when the last signal |
712 | as you don't register any with libev). Similarly, when the last signal |
585 | watcher for a signal is stopped libev will reset the signal handler to |
713 | watcher for a signal is stopped libev will reset the signal handler to |
586 | SIG_DFL (regardless of what it was set to before).</p> |
714 | SIG_DFL (regardless of what it was set to before).</p> |
… | |
… | |
592 | of the <code>SIGxxx</code> constants).</p> |
720 | of the <code>SIGxxx</code> constants).</p> |
593 | </dd> |
721 | </dd> |
594 | </dl> |
722 | </dl> |
595 | |
723 | |
596 | </div> |
724 | </div> |
597 | <h2 id="ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</h2> |
725 | <h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> |
598 | <div id="ev_child_wait_for_pid_status_changes-2"> |
726 | <div id="code_ev_child_code_wait_for_pid_stat-2"> |
599 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
727 | <p>Child watchers trigger when your process receives a SIGCHLD in response to |
600 | some child status changes (most typically when a child of yours dies).</p> |
728 | some child status changes (most typically when a child of yours dies).</p> |
601 | <dl> |
729 | <dl> |
602 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
730 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
603 | <dt>ev_child_set (ev_child *, int pid)</dt> |
731 | <dt>ev_child_set (ev_child *, int pid)</dt> |
604 | <dd> |
732 | <dd> |
605 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
733 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
606 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
734 | <i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look |
607 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
735 | at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see |
608 | the status word (use the macros from <code>sys/wait.h</code>). The <code>rpid</code> member |
736 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
|
|
737 | <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the |
609 | contains the pid of the process causing the status change.</p> |
738 | process causing the status change.</p> |
610 | </dd> |
739 | </dd> |
611 | </dl> |
740 | </dl> |
612 | |
741 | |
613 | </div> |
742 | </div> |
614 | <h2 id="ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</h2> |
743 | <h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> |
615 | <div id="ev_idle_when_you_ve_got_nothing_bett-2"> |
744 | <div id="code_ev_idle_code_when_you_ve_got_no-2"> |
616 | <p>Idle watchers trigger events when there are no other I/O or timer (or |
745 | <p>Idle watchers trigger events when there are no other events are pending |
617 | periodic) events pending. That is, as long as your process is busy |
746 | (prepare, check and other idle watchers do not count). That is, as long |
618 | handling sockets or timeouts it will not be called. But when your process |
747 | as your process is busy handling sockets or timeouts (or even signals, |
619 | is idle all idle watchers are being called again and again - until |
748 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
749 | watchers are being called again and again, once per event loop iteration - |
620 | stopped, that is, or your process receives more events.</p> |
750 | until stopped, that is, or your process receives more events and becomes |
|
|
751 | busy.</p> |
621 | <p>The most noteworthy effect is that as long as any idle watchers are |
752 | <p>The most noteworthy effect is that as long as any idle watchers are |
622 | active, the process will not block when waiting for new events.</p> |
753 | active, the process will not block when waiting for new events.</p> |
623 | <p>Apart from keeping your process non-blocking (which is a useful |
754 | <p>Apart from keeping your process non-blocking (which is a useful |
624 | effect on its own sometimes), idle watchers are a good place to do |
755 | effect on its own sometimes), idle watchers are a good place to do |
625 | "pseudo-background processing", or delay processing stuff to after the |
756 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
632 | believe me.</p> |
763 | believe me.</p> |
633 | </dd> |
764 | </dd> |
634 | </dl> |
765 | </dl> |
635 | |
766 | |
636 | </div> |
767 | </div> |
637 | <h2 id="prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</h2> |
768 | <h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> |
638 | <div id="prepare_and_check_your_hooks_into_th-2"> |
769 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
639 | <p>Prepare and check watchers usually (but not always) are used in |
770 | <p>Prepare and check watchers are usually (but not always) used in tandem: |
640 | tandom. Prepare watchers get invoked before the process blocks and check |
771 | prepare watchers get invoked before the process blocks and check watchers |
641 | watchers afterwards.</p> |
772 | afterwards.</p> |
642 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
773 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
643 | could be used, for example, to track variable changes, implement your own |
774 | could be used, for example, to track variable changes, implement your own |
644 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
775 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
645 | <p>This is done by examining in each prepare call which file descriptors need |
776 | <p>This is done by examining in each prepare call which file descriptors need |
646 | to be watched by the other library, registering ev_io watchers for them |
777 | to be watched by the other library, registering <code>ev_io</code> watchers for |
647 | and starting an ev_timer watcher for any timeouts (many libraries provide |
778 | them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries |
648 | just this functionality). Then, in the check watcher you check for any |
779 | provide just this functionality). Then, in the check watcher you check for |
649 | events that occured (by making your callbacks set soem flags for example) |
780 | any events that occured (by checking the pending status of all watchers |
650 | and call back into the library.</p> |
781 | and stopping them) and call back into the library. The I/O and timer |
|
|
782 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
783 | because you never know, you know?).</p> |
651 | <p>As another example, the perl Coro module uses these hooks to integrate |
784 | <p>As another example, the Perl Coro module uses these hooks to integrate |
652 | coroutines into libev programs, by yielding to other active coroutines |
785 | coroutines into libev programs, by yielding to other active coroutines |
653 | during each prepare and only letting the process block if no coroutines |
786 | during each prepare and only letting the process block if no coroutines |
654 | are ready to run.</p> |
787 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
788 | with priority higher than or equal to the event loop and one coroutine |
|
|
789 | of lower priority, but only once, using idle watchers to keep the event |
|
|
790 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
791 | low-priority coroutines to idle/background tasks).</p> |
655 | <dl> |
792 | <dl> |
656 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
793 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
657 | <dt>ev_check_init (ev_check *, callback)</dt> |
794 | <dt>ev_check_init (ev_check *, callback)</dt> |
658 | <dd> |
795 | <dd> |
659 | <p>Initialises and configures the prepare or check watcher - they have no |
796 | <p>Initialises and configures the prepare or check watcher - they have no |
660 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
797 | parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> |
661 | macros, but using them is utterly, utterly pointless.</p> |
798 | macros, but using them is utterly, utterly and completely pointless.</p> |
662 | </dd> |
799 | </dd> |
663 | </dl> |
800 | </dl> |
664 | |
801 | |
665 | </div> |
802 | </div> |
666 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
803 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
667 | <div id="OTHER_FUNCTIONS_CONTENT"> |
804 | <div id="OTHER_FUNCTIONS_CONTENT"> |
668 | <p>There are some other fucntions of possible interest. Described. Here. Now.</p> |
805 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
669 | <dl> |
806 | <dl> |
670 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
807 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
671 | <dd> |
808 | <dd> |
672 | <p>This function combines a simple timer and an I/O watcher, calls your |
809 | <p>This function combines a simple timer and an I/O watcher, calls your |
673 | callback on whichever event happens first and automatically stop both |
810 | callback on whichever event happens first and automatically stop both |
674 | watchers. This is useful if you want to wait for a single event on an fd |
811 | watchers. This is useful if you want to wait for a single event on an fd |
675 | or timeout without havign to allocate/configure/start/stop/free one or |
812 | or timeout without having to allocate/configure/start/stop/free one or |
676 | more watchers yourself.</p> |
813 | more watchers yourself.</p> |
677 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events is |
814 | <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events |
678 | ignored. Otherwise, an ev_io watcher for the given <code>fd</code> and <code>events</code> set |
815 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
679 | will be craeted and started.</p> |
816 | <code>events</code> set will be craeted and started.</p> |
680 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
817 | <p>If <code>timeout</code> is less than 0, then no timeout watcher will be |
681 | started. Otherwise an ev_timer watcher with after = <code>timeout</code> (and repeat |
818 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
682 | = 0) will be started.</p> |
819 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
|
|
820 | dubious value.</p> |
683 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and |
821 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets |
684 | gets passed an events set (normally a combination of EV_ERROR, EV_READ, |
822 | passed an <code>revents</code> set like normal event callbacks (a combination of |
685 | EV_WRITE or EV_TIMEOUT) and the <code>arg</code> value passed to <code>ev_once</code>:</p> |
823 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
|
|
824 | value passed to <code>ev_once</code>:</p> |
686 | <pre> static void stdin_ready (int revents, void *arg) |
825 | <pre> static void stdin_ready (int revents, void *arg) |
687 | { |
826 | { |
688 | if (revents & EV_TIMEOUT) |
827 | if (revents & EV_TIMEOUT) |
689 | /* doh, nothing entered */ |
828 | /* doh, nothing entered */; |
690 | else if (revents & EV_READ) |
829 | else if (revents & EV_READ) |
691 | /* stdin might have data for us, joy! */ |
830 | /* stdin might have data for us, joy! */; |
692 | } |
831 | } |
693 | |
832 | |
694 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
833 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
695 | |
834 | |
696 | </pre> |
835 | </pre> |
697 | </dd> |
836 | </dd> |
698 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
837 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
699 | <dd> |
838 | <dd> |
700 | <p>Feeds the given event set into the event loop, as if the specified event |
839 | <p>Feeds the given event set into the event loop, as if the specified event |
701 | has happened for the specified watcher (which must be a pointer to an |
840 | had happened for the specified watcher (which must be a pointer to an |
702 | initialised but not necessarily active event watcher).</p> |
841 | initialised but not necessarily started event watcher).</p> |
703 | </dd> |
842 | </dd> |
704 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
843 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
705 | <dd> |
844 | <dd> |
706 | <p>Feed an event on the given fd, as if a file descriptor backend detected it.</p> |
845 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
|
|
846 | the given events it.</p> |
707 | </dd> |
847 | </dd> |
708 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
848 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
709 | <dd> |
849 | <dd> |
710 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
850 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
711 | </dd> |
851 | </dd> |
712 | </dl> |
852 | </dl> |
|
|
853 | |
|
|
854 | </div> |
|
|
855 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
856 | <div id="LIBEVENT_EMULATION_CONTENT"> |
|
|
857 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
858 | emulate the internals of libevent, so here are some usage hints:</p> |
|
|
859 | <dl> |
|
|
860 | <dt>* Use it by including <event.h>, as usual.</dt> |
|
|
861 | <dt>* The following members are fully supported: ev_base, ev_callback, |
|
|
862 | ev_arg, ev_fd, ev_res, ev_events.</dt> |
|
|
863 | <dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
864 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
865 | it a private API).</dt> |
|
|
866 | <dt>* Priorities are not currently supported. Initialising priorities |
|
|
867 | will fail and all watchers will have the same priority, even though there |
|
|
868 | is an ev_pri field.</dt> |
|
|
869 | <dt>* Other members are not supported.</dt> |
|
|
870 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
|
|
871 | to use the libev header file and library.</dt> |
|
|
872 | </dl> |
|
|
873 | |
|
|
874 | </div> |
|
|
875 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
876 | <div id="C_SUPPORT_CONTENT"> |
|
|
877 | <p>TBD.</p> |
713 | |
878 | |
714 | </div> |
879 | </div> |
715 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
880 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
716 | <div id="AUTHOR_CONTENT"> |
881 | <div id="AUTHOR_CONTENT"> |
717 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
882 | <p>Marc Lehmann <libev@schmorp.de>.</p> |