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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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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> |
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26 | <ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li> |
25 | <ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
27 | <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> |
26 | </ul> |
28 | </ul> |
27 | </li> |
29 | </li> |
28 | <li><a href="#WATCHER_TYPES">WATCHER TYPES</a> |
30 | <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> |
31 | <ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> |
30 | <li><a href="#struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</a></li> |
32 | <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> |
33 | <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> |
34 | <li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> |
33 | <li><a href="#ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</a></li> |
35 | <li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> |
34 | <li><a href="#ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</a></li> |
36 | <li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> |
35 | <li><a href="#prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</a></li> |
37 | <li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> |
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38 | <li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</a></li> |
36 | </ul> |
39 | </ul> |
37 | </li> |
40 | </li> |
38 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
41 | <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> |
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42 | <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> |
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43 | <li><a href="#C_SUPPORT">C++ SUPPORT</a></li> |
39 | <li><a href="#AUTHOR">AUTHOR</a> |
44 | <li><a href="#AUTHOR">AUTHOR</a> |
40 | </li> |
45 | </li> |
41 | </ul><hr /> |
46 | </ul><hr /> |
42 | <!-- INDEX END --> |
47 | <!-- INDEX END --> |
43 | |
48 | |
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55 | </div> |
60 | </div> |
56 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
61 | <h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
57 | <div id="DESCRIPTION_CONTENT"> |
62 | <div id="DESCRIPTION_CONTENT"> |
58 | <p>Libev is an event loop: you register interest in certain events (such as a |
63 | <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 |
64 | file descriptor being readable or a timeout occuring), and it will manage |
60 | these event sources and provide your program events.</p> |
65 | 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 |
66 | <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 |
67 | (or thread) by executing the <i>event loop</i> handler, and will then |
63 | communicate events via a callback mechanism.</p> |
68 | communicate events via a callback mechanism.</p> |
64 | <p>You register interest in certain events by registering so-called <i>event |
69 | <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 |
70 | watchers</i>, which are relatively small C structures you initialise with the |
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71 | <div id="FEATURES_CONTENT"> |
76 | <div id="FEATURES_CONTENT"> |
72 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
77 | <p>Libev supports select, poll, the linux-specific epoll and the bsd-specific |
73 | kqueue mechanisms for file descriptor events, relative timers, absolute |
78 | kqueue mechanisms for file descriptor events, relative timers, absolute |
74 | timers with customised rescheduling, signal events, process status change |
79 | timers with customised rescheduling, signal events, process status change |
75 | events (related to SIGCHLD), and event watchers dealing with the event |
80 | events (related to SIGCHLD), and event watchers dealing with the event |
76 | loop mechanism itself (idle, prepare and check watchers).</p> |
81 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
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82 | fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing |
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83 | it to libevent for example).</p> |
77 | |
84 | |
78 | </div> |
85 | </div> |
79 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
86 | <h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
80 | <div id="CONVENTIONS_CONTENT"> |
87 | <div id="CONVENTIONS_CONTENT"> |
81 | <p>Libev is very configurable. In this manual the default configuration |
88 | <p>Libev is very configurable. In this manual the default configuration |
82 | will be described, which supports multiple event loops. For more info |
89 | will be described, which supports multiple event loops. For more info |
83 | about various configuraiton options please have a look at the file |
90 | 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 |
91 | <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 |
92 | 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>) |
93 | argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) |
87 | will not have this argument.</p> |
94 | will not have this argument.</p> |
88 | |
95 | |
89 | </div> |
96 | </div> |
90 | <h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
97 | <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"> |
98 | <div id="TIME_REPRESENTATION_CONTENT"> |
92 | <p>Libev represents time as a single floating point number, representing the |
99 | <p>Libev represents time as a single floating point number, representing the |
93 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
100 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
94 | the beginning of 1970, details are complicated, don't ask). This type is |
101 | 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 |
102 | called <code>ev_tstamp</code>, which is what you should use too. It usually aliases |
96 | to the double type in C.</p> |
103 | to the <code>double</code> type in C, and when you need to do any calculations on |
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104 | it, you should treat it as such.</p> |
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105 | |
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106 | |
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107 | |
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108 | |
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109 | |
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110 | </div> |
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111 | <h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
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112 | <div id="GLOBAL_FUNCTIONS_CONTENT"> |
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113 | <p>These functions can be called anytime, even before initialising the |
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114 | library in any way.</p> |
97 | <dl> |
115 | <dl> |
98 | <dt>ev_tstamp ev_time ()</dt> |
116 | <dt>ev_tstamp ev_time ()</dt> |
99 | <dd> |
117 | <dd> |
100 | <p>Returns the current time as libev would use it.</p> |
118 | <p>Returns the current time as libev would use it. Please note that the |
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119 | <code>ev_now</code> function is usually faster and also often returns the timestamp |
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120 | you actually want to know.</p> |
101 | </dd> |
121 | </dd> |
102 | <dt>int ev_version_major ()</dt> |
122 | <dt>int ev_version_major ()</dt> |
103 | <dt>int ev_version_minor ()</dt> |
123 | <dt>int ev_version_minor ()</dt> |
104 | <dd> |
124 | <dd> |
105 | <p>You can find out the major and minor version numbers of the library |
125 | <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 |
126 | 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 |
127 | <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 |
128 | 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> |
129 | version of the library your program was compiled against.</p> |
110 | <p>Usually, its a good idea to terminate if the major versions mismatch, |
130 | <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 |
131 | as this indicates an incompatible change. Minor versions are usually |
112 | compatible to older versions, so a larger minor version alone is usually |
132 | compatible to older versions, so a larger minor version alone is usually |
113 | not a problem.</p> |
133 | not a problem.</p> |
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134 | <p>Example: make sure we haven't accidentally been linked against the wrong |
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135 | version:</p> |
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136 | <pre> assert (("libev version mismatch", |
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137 | ev_version_major () == EV_VERSION_MAJOR |
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138 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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139 | |
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140 | </pre> |
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141 | </dd> |
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142 | <dt>unsigned int ev_supported_backends ()</dt> |
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143 | <dd> |
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144 | <p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code> |
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145 | value) compiled into this binary of libev (independent of their |
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146 | availability on the system you are running on). See <code>ev_default_loop</code> for |
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147 | a description of the set values.</p> |
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148 | <p>Example: make sure we have the epoll method, because yeah this is cool and |
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149 | a must have and can we have a torrent of it please!!!11</p> |
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150 | <pre> assert (("sorry, no epoll, no sex", |
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151 | ev_supported_backends () & EVBACKEND_EPOLL)); |
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152 | |
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153 | </pre> |
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154 | </dd> |
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155 | <dt>unsigned int ev_recommended_backends ()</dt> |
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156 | <dd> |
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157 | <p>Return the set of all backends compiled into this binary of libev and also |
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158 | recommended for this platform. This set is often smaller than the one |
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159 | returned by <code>ev_supported_backends</code>, as for example kqueue is broken on |
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160 | most BSDs and will not be autodetected unless you explicitly request it |
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161 | (assuming you know what you are doing). This is the set of backends that |
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162 | libev will probe for if you specify no backends explicitly.</p> |
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163 | </dd> |
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164 | <dt>unsigned int ev_embeddable_backends ()</dt> |
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165 | <dd> |
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166 | <p>Returns the set of backends that are embeddable in other event loops. This |
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167 | is the theoretical, all-platform, value. To find which backends |
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168 | might be supported on the current system, you would need to look at |
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169 | <code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for |
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170 | recommended ones.</p> |
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171 | <p>See the description of <code>ev_embed</code> watchers for more info.</p> |
114 | </dd> |
172 | </dd> |
115 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
173 | <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> |
116 | <dd> |
174 | <dd> |
117 | <p>Sets the allocation function to use (the prototype is similar to the |
175 | <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 |
176 | 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 |
177 | and free memory (no surprises here). If it returns zero when memory |
120 | might abort or take some potentially destructive action. The default is |
178 | needs to be allocated, the library might abort or take some potentially |
121 | your system realloc function.</p> |
179 | destructive action. The default is your system realloc function.</p> |
122 | <p>You could override this function in high-availability programs to, say, |
180 | <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, |
181 | 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> |
182 | or even to sleep a while and retry until some memory is available.</p> |
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183 | <p>Example: replace the libev allocator with one that waits a bit and then |
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184 | retries: better than mine).</p> |
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185 | <pre> static void * |
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186 | persistent_realloc (void *ptr, long size) |
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187 | { |
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188 | for (;;) |
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189 | { |
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190 | void *newptr = realloc (ptr, size); |
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191 | |
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192 | if (newptr) |
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193 | return newptr; |
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194 | |
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195 | sleep (60); |
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196 | } |
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197 | } |
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198 | |
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199 | ... |
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200 | ev_set_allocator (persistent_realloc); |
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201 | |
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202 | </pre> |
125 | </dd> |
203 | </dd> |
126 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
204 | <dt>ev_set_syserr_cb (void (*cb)(const char *msg));</dt> |
127 | <dd> |
205 | <dd> |
128 | <p>Set the callback function to call on a retryable syscall error (such |
206 | <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 |
207 | as failed select, poll, epoll_wait). The message is a printable string |
130 | indicating the system call or subsystem causing the problem. If this |
208 | 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 |
209 | 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 |
210 | 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 |
211 | requested operation, or, if the condition doesn't go away, do bad stuff |
134 | (such as abort).</p> |
212 | (such as abort).</p> |
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213 | <p>Example: do the same thing as libev does internally:</p> |
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214 | <pre> static void |
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215 | fatal_error (const char *msg) |
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216 | { |
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217 | perror (msg); |
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218 | abort (); |
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219 | } |
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220 | |
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221 | ... |
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222 | ev_set_syserr_cb (fatal_error); |
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223 | |
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224 | </pre> |
135 | </dd> |
225 | </dd> |
136 | </dl> |
226 | </dl> |
137 | |
227 | |
138 | </div> |
228 | </div> |
139 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
229 | <h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> |
140 | <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> |
230 | <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 |
231 | <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 |
232 | types of such loops, the <i>default</i> loop, which supports signals and child |
143 | events, and dynamically created loops which do not.</p> |
233 | 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 |
234 | <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 |
235 | 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 |
236 | 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 |
237 | 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> |
238 | threads, make sure you lock (this is usually a bad idea, though, even if |
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239 | done correctly, because it's hideous and inefficient).</p> |
149 | <dl> |
240 | <dl> |
150 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
241 | <dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt> |
151 | <dd> |
242 | <dd> |
152 | <p>This will initialise the default event loop if it hasn't been initialised |
243 | <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 |
244 | 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 |
245 | false. If it already was initialised it simply returns it (and ignores the |
155 | flags).</p> |
246 | 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 |
247 | <p>If you don't know what event loop to use, use the one returned from this |
157 | function.</p> |
248 | function.</p> |
158 | <p>The flags argument can be used to specify special behaviour or specific |
249 | <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> |
250 | backends to use, and is usually specified as <code>0</code> (or <code>EVFLAG_AUTO</code>).</p> |
160 | <p>It supports the following flags:</p> |
251 | <p>The following flags are supported:</p> |
161 | <p> |
252 | <p> |
162 | <dl> |
253 | <dl> |
163 | <dt>EVFLAG_AUTO</dt> |
254 | <dt><code>EVFLAG_AUTO</code></dt> |
164 | <dd> |
255 | <dd> |
165 | <p>The default flags value. Use this if you have no clue (its the right |
256 | <p>The default flags value. Use this if you have no clue (it's the right |
166 | thing, believe me).</p> |
257 | thing, believe me).</p> |
167 | </dd> |
258 | </dd> |
168 | <dt>EVFLAG_NOENV</dt> |
259 | <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> |
260 | <dd> |
176 | <dt>EVMETHOD_SELECT portable select backend</dt> |
261 | <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> |
262 | or setgid) then libev will <i>not</i> look at the environment variable |
178 | <dt>EVMETHOD_EPOLL linux only</dt> |
263 | <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will |
179 | <dt>EVMETHOD_KQUEUE some bsds only</dt> |
264 | override the flags completely if it is found in the environment. This is |
180 | <dt>EVMETHOD_DEVPOLL solaris 8 only</dt> |
265 | useful to try out specific backends to test their performance, or to work |
181 | <dt>EVMETHOD_PORT solaris 10 only</dt> |
266 | around bugs.</p> |
182 | <dd> |
267 | </dd> |
183 | <p>If one or more of these are ored into the flags value, then only these |
268 | <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 |
269 | <dd> |
185 | specified, any backend will do.</p> |
270 | <p>This is your standard select(2) backend. Not <i>completely</i> standard, as |
|
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271 | libev tries to roll its own fd_set with no limits on the number of fds, |
|
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272 | but if that fails, expect a fairly low limit on the number of fds when |
|
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273 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
|
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274 | the fastest backend for a low number of fds.</p> |
|
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275 | </dd> |
|
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276 | <dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt> |
|
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277 | <dd> |
|
|
278 | <p>And this is your standard poll(2) backend. It's more complicated than |
|
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279 | select, but handles sparse fds better and has no artificial limit on the |
|
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280 | number of fds you can use (except it will slow down considerably with a |
|
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281 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p> |
|
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282 | </dd> |
|
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283 | <dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt> |
|
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284 | <dd> |
|
|
285 | <p>For few fds, this backend is a bit little slower than poll and select, |
|
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286 | but it scales phenomenally better. While poll and select usually scale like |
|
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287 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
|
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288 | either O(1) or O(active_fds).</p> |
|
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289 | <p>While stopping and starting an I/O watcher in the same iteration will |
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290 | result in some caching, there is still a syscall per such incident |
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291 | (because the fd could point to a different file description now), so its |
|
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292 | best to avoid that. Also, dup()ed file descriptors might not work very |
|
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293 | well if you register events for both fds.</p> |
|
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294 | <p>Please note that epoll sometimes generates spurious notifications, so you |
|
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295 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
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296 | (or space) is available.</p> |
|
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297 | </dd> |
|
|
298 | <dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt> |
|
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299 | <dd> |
|
|
300 | <p>Kqueue deserves special mention, as at the time of this writing, it |
|
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301 | was broken on all BSDs except NetBSD (usually it doesn't work with |
|
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302 | anything but sockets and pipes, except on Darwin, where of course its |
|
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303 | completely useless). For this reason its not being "autodetected" |
|
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304 | unless you explicitly specify it explicitly in the flags (i.e. using |
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305 | <code>EVBACKEND_KQUEUE</code>).</p> |
|
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306 | <p>It scales in the same way as the epoll backend, but the interface to the |
|
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307 | kernel is more efficient (which says nothing about its actual speed, of |
|
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308 | course). While starting and stopping an I/O watcher does not cause an |
|
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309 | extra syscall as with epoll, it still adds up to four event changes per |
|
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310 | incident, so its best to avoid that.</p> |
|
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311 | </dd> |
|
|
312 | <dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt> |
|
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313 | <dd> |
|
|
314 | <p>This is not implemented yet (and might never be).</p> |
|
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315 | </dd> |
|
|
316 | <dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt> |
|
|
317 | <dd> |
|
|
318 | <p>This uses the Solaris 10 port mechanism. As with everything on Solaris, |
|
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319 | it's really slow, but it still scales very well (O(active_fds)).</p> |
|
|
320 | <p>Please note that solaris ports can result in a lot of spurious |
|
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321 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
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322 | blocking when no data (or space) is available.</p> |
|
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323 | </dd> |
|
|
324 | <dt><code>EVBACKEND_ALL</code></dt> |
|
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325 | <dd> |
|
|
326 | <p>Try all backends (even potentially broken ones that wouldn't be tried |
|
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327 | with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as |
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328 | <code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p> |
186 | </dd> |
329 | </dd> |
187 | </dl> |
330 | </dl> |
188 | </p> |
331 | </p> |
|
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332 | <p>If one or more of these are ored into the flags value, then only these |
|
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333 | backends will be tried (in the reverse order as given here). If none are |
|
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334 | specified, most compiled-in backend will be tried, usually in reverse |
|
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335 | order of their flag values :)</p> |
|
|
336 | <p>The most typical usage is like this:</p> |
|
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337 | <pre> if (!ev_default_loop (0)) |
|
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338 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
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339 | |
|
|
340 | </pre> |
|
|
341 | <p>Restrict libev to the select and poll backends, and do not allow |
|
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342 | environment settings to be taken into account:</p> |
|
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343 | <pre> ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
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344 | |
|
|
345 | </pre> |
|
|
346 | <p>Use whatever libev has to offer, but make sure that kqueue is used if |
|
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347 | available (warning, breaks stuff, best use only with your own private |
|
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348 | event loop and only if you know the OS supports your types of fds):</p> |
|
|
349 | <pre> ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
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350 | |
|
|
351 | </pre> |
189 | </dd> |
352 | </dd> |
190 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
353 | <dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt> |
191 | <dd> |
354 | <dd> |
192 | <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is |
355 | <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 |
356 | always distinct from the default loop. Unlike the default loop, it cannot |
194 | handle signal and child watchers, and attempts to do so will be greeted by |
357 | handle signal and child watchers, and attempts to do so will be greeted by |
195 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
358 | undefined behaviour (or a failed assertion if assertions are enabled).</p> |
|
|
359 | <p>Example: try to create a event loop that uses epoll and nothing else.</p> |
|
|
360 | <pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
|
361 | if (!epoller) |
|
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362 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
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363 | |
|
|
364 | </pre> |
196 | </dd> |
365 | </dd> |
197 | <dt>ev_default_destroy ()</dt> |
366 | <dt>ev_default_destroy ()</dt> |
198 | <dd> |
367 | <dd> |
199 | <p>Destroys the default loop again (frees all memory and kernel state |
368 | <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 |
369 | etc.). None of the active event watchers will be stopped in the normal |
201 | any way whatsoever, although you cnanot rely on this :).</p> |
370 | sense, so e.g. <code>ev_is_active</code> might still return true. It is your |
|
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371 | responsibility to either stop all watchers cleanly yoursef <i>before</i> |
|
|
372 | calling this function, or cope with the fact afterwards (which is usually |
|
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373 | the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them |
|
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374 | for example).</p> |
202 | </dd> |
375 | </dd> |
203 | <dt>ev_loop_destroy (loop)</dt> |
376 | <dt>ev_loop_destroy (loop)</dt> |
204 | <dd> |
377 | <dd> |
205 | <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an |
378 | <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> |
379 | earlier call to <code>ev_loop_new</code>.</p> |
… | |
… | |
209 | <dd> |
382 | <dd> |
210 | <p>This function reinitialises the kernel state for backends that have |
383 | <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 |
384 | 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 |
385 | after forking, in either the parent or child process (or both, but that |
213 | again makes little sense).</p> |
386 | again makes little sense).</p> |
214 | <p>You <i>must</i> call this function after forking if and only if you want to |
387 | <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 |
388 | only if you want to use the event library in both processes. If you just |
216 | have to call it.</p> |
389 | 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 |
390 | <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 |
391 | 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> |
392 | quite nicely into a call to <code>pthread_atfork</code>:</p> |
220 | <pre> pthread_atfork (0, 0, ev_default_fork); |
393 | <pre> pthread_atfork (0, 0, ev_default_fork); |
221 | |
394 | |
222 | </pre> |
395 | </pre> |
|
|
396 | <p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use |
|
|
397 | without calling this function, so if you force one of those backends you |
|
|
398 | do not need to care.</p> |
223 | </dd> |
399 | </dd> |
224 | <dt>ev_loop_fork (loop)</dt> |
400 | <dt>ev_loop_fork (loop)</dt> |
225 | <dd> |
401 | <dd> |
226 | <p>Like <code>ev_default_fork</code>, but acts on an event loop created by |
402 | <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 |
403 | <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> |
404 | after fork, and how you do this is entirely your own problem.</p> |
229 | </dd> |
405 | </dd> |
230 | <dt>unsigned int ev_method (loop)</dt> |
406 | <dt>unsigned int ev_backend (loop)</dt> |
231 | <dd> |
407 | <dd> |
232 | <p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in |
408 | <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in |
233 | use.</p> |
409 | use.</p> |
234 | </dd> |
410 | </dd> |
235 | <dt>ev_tstamp = ev_now (loop)</dt> |
411 | <dt>ev_tstamp ev_now (loop)</dt> |
236 | <dd> |
412 | <dd> |
237 | <p>Returns the current "event loop time", which is the time the event loop |
413 | <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 |
414 | received events and started processing them. This timestamp does not |
239 | as long as callbacks are being processed, and this is also the base time |
415 | change as long as callbacks are being processed, and this is also the base |
240 | used for relative timers. You can treat it as the timestamp of the event |
416 | time used for relative timers. You can treat it as the timestamp of the |
241 | occuring (or more correctly, the mainloop finding out about it).</p> |
417 | event occuring (or more correctly, libev finding out about it).</p> |
242 | </dd> |
418 | </dd> |
243 | <dt>ev_loop (loop, int flags)</dt> |
419 | <dt>ev_loop (loop, int flags)</dt> |
244 | <dd> |
420 | <dd> |
245 | <p>Finally, this is it, the event handler. This function usually is called |
421 | <p>Finally, this is it, the event handler. This function usually is called |
246 | after you initialised all your watchers and you want to start handling |
422 | after you initialised all your watchers and you want to start handling |
247 | events.</p> |
423 | events.</p> |
248 | <p>If the flags argument is specified as 0, it will not return until either |
424 | <p>If the flags argument is specified as <code>0</code>, it will not return until |
249 | no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
425 | either no event watchers are active anymore or <code>ev_unloop</code> was called.</p> |
|
|
426 | <p>Please note that an explicit <code>ev_unloop</code> is usually better than |
|
|
427 | relying on all watchers to be stopped when deciding when a program has |
|
|
428 | finished (especially in interactive programs), but having a program that |
|
|
429 | automatically loops as long as it has to and no longer by virtue of |
|
|
430 | relying on its watchers stopping correctly is a thing of beauty.</p> |
250 | <p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle |
431 | <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 |
432 | those events and any outstanding ones, but will not block your process in |
252 | case there are no events.</p> |
433 | 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 |
434 | <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 |
435 | neccessary) and will handle those and any outstanding ones. It will block |
255 | your process until at least one new event arrives.</p> |
436 | your process until at least one new event arrives, and will return after |
256 | <p>This flags value could be used to implement alternative looping |
437 | one iteration of the loop. This is useful if you are waiting for some |
257 | constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and |
438 | external event in conjunction with something not expressible using other |
258 | more generic mechanism.</p> |
439 | libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is |
|
|
440 | usually a better approach for this kind of thing.</p> |
|
|
441 | <p>Here are the gory details of what <code>ev_loop</code> does:</p> |
|
|
442 | <pre> * If there are no active watchers (reference count is zero), return. |
|
|
443 | - Queue prepare watchers and then call all outstanding watchers. |
|
|
444 | - If we have been forked, recreate the kernel state. |
|
|
445 | - Update the kernel state with all outstanding changes. |
|
|
446 | - Update the "event loop time". |
|
|
447 | - Calculate for how long to block. |
|
|
448 | - Block the process, waiting for any events. |
|
|
449 | - Queue all outstanding I/O (fd) events. |
|
|
450 | - Update the "event loop time" and do time jump handling. |
|
|
451 | - Queue all outstanding timers. |
|
|
452 | - Queue all outstanding periodics. |
|
|
453 | - If no events are pending now, queue all idle watchers. |
|
|
454 | - Queue all check watchers. |
|
|
455 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
456 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
457 | be handled here by queueing them when their watcher gets executed. |
|
|
458 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
|
459 | were used, return, otherwise continue with step *. |
|
|
460 | |
|
|
461 | </pre> |
|
|
462 | <p>Example: queue some jobs and then loop until no events are outsanding |
|
|
463 | anymore.</p> |
|
|
464 | <pre> ... queue jobs here, make sure they register event watchers as long |
|
|
465 | ... as they still have work to do (even an idle watcher will do..) |
|
|
466 | ev_loop (my_loop, 0); |
|
|
467 | ... jobs done. yeah! |
|
|
468 | |
|
|
469 | </pre> |
259 | </dd> |
470 | </dd> |
260 | <dt>ev_unloop (loop, how)</dt> |
471 | <dt>ev_unloop (loop, how)</dt> |
261 | <dd> |
472 | <dd> |
262 | <p>Can be used to make a call to <code>ev_loop</code> return early. The <code>how</code> argument |
473 | <p>Can be used to make a call to <code>ev_loop</code> return early (but only after it |
|
|
474 | 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> |
475 | <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> |
476 | <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p> |
265 | calls return.</p> |
|
|
266 | </dd> |
477 | </dd> |
267 | <dt>ev_ref (loop)</dt> |
478 | <dt>ev_ref (loop)</dt> |
268 | <dt>ev_unref (loop)</dt> |
479 | <dt>ev_unref (loop)</dt> |
269 | <dd> |
480 | <dd> |
270 | <p>Ref/unref can be used to add or remove a refcount on the event loop: Every |
481 | <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 |
482 | 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 |
483 | 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 |
484 | 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 |
485 | 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 |
486 | 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 |
487 | 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 |
488 | no event watchers registered by it are active. It is also an excellent |
278 | before stop.</p> |
489 | way to do this for generic recurring timers or from within third-party |
|
|
490 | libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> |
|
|
491 | <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> |
|
|
492 | running when nothing else is active.</p> |
|
|
493 | <pre> struct dv_signal exitsig; |
|
|
494 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
495 | ev_signal_start (myloop, &exitsig); |
|
|
496 | evf_unref (myloop); |
|
|
497 | |
|
|
498 | </pre> |
|
|
499 | <p>Example: for some weird reason, unregister the above signal handler again.</p> |
|
|
500 | <pre> ev_ref (myloop); |
|
|
501 | ev_signal_stop (myloop, &exitsig); |
|
|
502 | |
|
|
503 | </pre> |
279 | </dd> |
504 | </dd> |
280 | </dl> |
505 | </dl> |
281 | |
506 | |
282 | </div> |
507 | </div> |
283 | <h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> |
508 | <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"> |
509 | <div id="ANATOMY_OF_A_WATCHER_CONTENT"> |
285 | <p>A watcher is a structure that you create and register to record your |
510 | <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 |
511 | 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> |
512 | 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) |
513 | <pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
289 | { |
514 | { |
290 | ev_io_stop (w); |
515 | ev_io_stop (w); |
291 | ev_unloop (loop, EVUNLOOP_ALL); |
516 | ev_unloop (loop, EVUNLOOP_ALL); |
292 | } |
517 | } |
… | |
… | |
315 | with a watcher-specific start function (<code>ev_<type>_start (loop, watcher |
540 | 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 |
541 | *)</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> |
542 | 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 |
543 | <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 |
544 | must not touch the values stored in it. Most specifically you must never |
320 | reinitialise it or call its set method.</p> |
545 | reinitialise it or call its <code>set</code> macro.</p> |
321 | <p>You cna check wether an event is active by calling the <code>ev_is_active |
|
|
322 | (watcher *)</code> macro. To see wether an event is outstanding (but the |
|
|
323 | callback for it has not been called yet) you cna use the <code>ev_is_pending |
|
|
324 | (watcher *)</code> macro.</p> |
|
|
325 | <p>Each and every callback receives the event loop pointer as first, the |
546 | <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 |
547 | registered watcher structure as second, and a bitset of received events as |
327 | third argument.</p> |
548 | third argument.</p> |
328 | <p>The rceeived events usually include a single bit per event type received |
549 | <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 |
550 | (you can receive multiple events at the same time). The possible bit masks |
330 | are:</p> |
551 | are:</p> |
331 | <dl> |
552 | <dl> |
332 | <dt>EV_READ</dt> |
553 | <dt><code>EV_READ</code></dt> |
333 | <dt>EV_WRITE</dt> |
554 | <dt><code>EV_WRITE</code></dt> |
334 | <dd> |
555 | <dd> |
335 | <p>The file descriptor in the ev_io watcher has become readable and/or |
556 | <p>The file descriptor in the <code>ev_io</code> watcher has become readable and/or |
336 | writable.</p> |
557 | writable.</p> |
337 | </dd> |
558 | </dd> |
338 | <dt>EV_TIMEOUT</dt> |
559 | <dt><code>EV_TIMEOUT</code></dt> |
339 | <dd> |
|
|
340 | <p>The ev_timer watcher has timed out.</p> |
|
|
341 | </dd> |
560 | <dd> |
342 | <dt>EV_PERIODIC</dt> |
561 | <p>The <code>ev_timer</code> watcher has timed out.</p> |
343 | <dd> |
562 | </dd> |
344 | <p>The ev_periodic watcher has timed out.</p> |
563 | <dt><code>EV_PERIODIC</code></dt> |
345 | </dd> |
564 | <dd> |
346 | <dt>EV_SIGNAL</dt> |
565 | <p>The <code>ev_periodic</code> watcher has timed out.</p> |
347 | <dd> |
566 | </dd> |
|
|
567 | <dt><code>EV_SIGNAL</code></dt> |
|
|
568 | <dd> |
348 | <p>The signal specified in the ev_signal watcher has been received by a thread.</p> |
569 | <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> |
570 | </dd> |
|
|
571 | <dt><code>EV_CHILD</code></dt> |
|
|
572 | <dd> |
352 | <p>The pid specified in the ev_child watcher has received a status change.</p> |
573 | <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> |
574 | </dd> |
|
|
575 | <dt><code>EV_IDLE</code></dt> |
|
|
576 | <dd> |
356 | <p>The ev_idle watcher has determined that you have nothing better to do.</p> |
577 | <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> |
578 | </dd> |
|
|
579 | <dt><code>EV_PREPARE</code></dt> |
|
|
580 | <dt><code>EV_CHECK</code></dt> |
|
|
581 | <dd> |
361 | <p>All ev_prepare watchers are invoked just <i>before</i> <code>ev_loop</code> starts |
582 | <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 |
583 | 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 |
584 | <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 |
585 | 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 |
586 | 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 |
587 | (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep |
367 | <code>ev_loop</code> from blocking).</p> |
588 | <code>ev_loop</code> from blocking).</p> |
368 | </dd> |
589 | </dd> |
369 | <dt>EV_ERROR</dt> |
590 | <dt><code>EV_ERROR</code></dt> |
370 | <dd> |
591 | <dd> |
371 | <p>An unspecified error has occured, the watcher has been stopped. This might |
592 | <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 |
593 | 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 |
594 | 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 |
595 | problem. You best act on it by reporting the problem and somehow coping |
… | |
… | |
380 | programs, though, so beware.</p> |
601 | programs, though, so beware.</p> |
381 | </dd> |
602 | </dd> |
382 | </dl> |
603 | </dl> |
383 | |
604 | |
384 | </div> |
605 | </div> |
|
|
606 | <h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2> |
|
|
607 | <div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2"> |
|
|
608 | <p>In the following description, <code>TYPE</code> stands for the watcher type, |
|
|
609 | e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> |
|
|
610 | <dl> |
|
|
611 | <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> |
|
|
612 | <dd> |
|
|
613 | <p>This macro initialises the generic portion of a watcher. The contents |
|
|
614 | of the watcher object can be arbitrary (so <code>malloc</code> will do). Only |
|
|
615 | the generic parts of the watcher are initialised, you <i>need</i> to call |
|
|
616 | the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the |
|
|
617 | type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro |
|
|
618 | which rolls both calls into one.</p> |
|
|
619 | <p>You can reinitialise a watcher at any time as long as it has been stopped |
|
|
620 | (or never started) and there are no pending events outstanding.</p> |
|
|
621 | <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
622 | int revents)</code>.</p> |
|
|
623 | </dd> |
|
|
624 | <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> |
|
|
625 | <dd> |
|
|
626 | <p>This macro initialises the type-specific parts of a watcher. You need to |
|
|
627 | call <code>ev_init</code> at least once before you call this macro, but you can |
|
|
628 | call <code>ev_TYPE_set</code> any number of times. You must not, however, call this |
|
|
629 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
630 | difference to the <code>ev_init</code> macro).</p> |
|
|
631 | <p>Although some watcher types do not have type-specific arguments |
|
|
632 | (e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p> |
|
|
633 | </dd> |
|
|
634 | <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt> |
|
|
635 | <dd> |
|
|
636 | <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro |
|
|
637 | calls into a single call. This is the most convinient method to initialise |
|
|
638 | a watcher. The same limitations apply, of course.</p> |
|
|
639 | </dd> |
|
|
640 | <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
641 | <dd> |
|
|
642 | <p>Starts (activates) the given watcher. Only active watchers will receive |
|
|
643 | events. If the watcher is already active nothing will happen.</p> |
|
|
644 | </dd> |
|
|
645 | <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt> |
|
|
646 | <dd> |
|
|
647 | <p>Stops the given watcher again (if active) and clears the pending |
|
|
648 | status. It is possible that stopped watchers are pending (for example, |
|
|
649 | non-repeating timers are being stopped when they become pending), but |
|
|
650 | <code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If |
|
|
651 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
652 | good idea to always call its <code>ev_TYPE_stop</code> function.</p> |
|
|
653 | </dd> |
|
|
654 | <dt>bool ev_is_active (ev_TYPE *watcher)</dt> |
|
|
655 | <dd> |
|
|
656 | <p>Returns a true value iff the watcher is active (i.e. it has been started |
|
|
657 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
658 | it.</p> |
|
|
659 | </dd> |
|
|
660 | <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> |
|
|
661 | <dd> |
|
|
662 | <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
663 | events but its callback has not yet been invoked). As long as a watcher |
|
|
664 | is pending (but not active) you must not call an init function on it (but |
|
|
665 | <code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to |
|
|
666 | libev (e.g. you cnanot <code>free ()</code> it).</p> |
|
|
667 | </dd> |
|
|
668 | <dt>callback = ev_cb (ev_TYPE *watcher)</dt> |
|
|
669 | <dd> |
|
|
670 | <p>Returns the callback currently set on the watcher.</p> |
|
|
671 | </dd> |
|
|
672 | <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> |
|
|
673 | <dd> |
|
|
674 | <p>Change the callback. You can change the callback at virtually any time |
|
|
675 | (modulo threads).</p> |
|
|
676 | </dd> |
|
|
677 | </dl> |
|
|
678 | |
|
|
679 | |
|
|
680 | |
|
|
681 | |
|
|
682 | |
|
|
683 | </div> |
385 | <h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> |
684 | <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"> |
685 | <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 |
686 | <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 |
687 | 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 |
688 | 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 |
689 | 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 |
690 | member, you can also "subclass" the watcher type and provide your own |
392 | data:</p> |
691 | data:</p> |
393 | <pre> struct my_io |
692 | <pre> struct my_io |
… | |
… | |
419 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
718 | <h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> |
420 | <div id="WATCHER_TYPES_CONTENT"> |
719 | <div id="WATCHER_TYPES_CONTENT"> |
421 | <p>This section describes each watcher in detail, but will not repeat |
720 | <p>This section describes each watcher in detail, but will not repeat |
422 | information given in the last section.</p> |
721 | information given in the last section.</p> |
423 | |
722 | |
|
|
723 | |
|
|
724 | |
|
|
725 | |
|
|
726 | |
424 | </div> |
727 | </div> |
425 | <h2 id="struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</h2> |
728 | <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"> |
729 | <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 |
730 | <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 |
731 | in each iteration of the event loop (This behaviour is called |
429 | level-triggering because you keep receiving events as long as the |
732 | 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 |
733 | 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> |
734 | act on the event and neither want to receive future events).</p> |
|
|
735 | <p>In general you can register as many read and/or write event watchers per |
|
|
736 | fd as you want (as long as you don't confuse yourself). Setting all file |
|
|
737 | descriptors to non-blocking mode is also usually a good idea (but not |
|
|
738 | required if you know what you are doing).</p> |
|
|
739 | <p>You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
740 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
741 | descriptors correctly if you register interest in two or more fds pointing |
|
|
742 | to the same underlying file/socket etc. description (that is, they share |
|
|
743 | the same underlying "file open").</p> |
|
|
744 | <p>If you must do this, then force the use of a known-to-be-good backend |
|
|
745 | (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and |
|
|
746 | <code>EVBACKEND_POLL</code>).</p> |
432 | <dl> |
747 | <dl> |
433 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
748 | <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> |
434 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
749 | <dt>ev_io_set (ev_io *, int fd, int events)</dt> |
435 | <dd> |
750 | <dd> |
436 | <p>Configures an ev_io watcher. The fd is the file descriptor to rceeive |
751 | <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 | |
752 | 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> |
753 | EV_WRITE</code> to receive the given events.</p> |
|
|
754 | <p>Please note that most of the more scalable backend mechanisms (for example |
|
|
755 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
756 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
757 | treat callback invocation as hint only), or retest separately with a safe |
|
|
758 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
759 | <code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this |
|
|
760 | problem. Also note that it is quite easy to have your callback invoked |
|
|
761 | when the readyness condition is no longer valid even when employing |
|
|
762 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
763 | I/O unconditionally.</p> |
439 | </dd> |
764 | </dd> |
440 | </dl> |
765 | </dl> |
|
|
766 | <p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well |
|
|
767 | readable, but only once. Since it is likely line-buffered, you could |
|
|
768 | attempt to read a whole line in the callback:</p> |
|
|
769 | <pre> static void |
|
|
770 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
771 | { |
|
|
772 | ev_io_stop (loop, w); |
|
|
773 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
774 | } |
441 | |
775 | |
|
|
776 | ... |
|
|
777 | struct ev_loop *loop = ev_default_init (0); |
|
|
778 | struct ev_io stdin_readable; |
|
|
779 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
780 | ev_io_start (loop, &stdin_readable); |
|
|
781 | ev_loop (loop, 0); |
|
|
782 | |
|
|
783 | |
|
|
784 | |
|
|
785 | |
|
|
786 | </pre> |
|
|
787 | |
442 | </div> |
788 | </div> |
443 | <h2 id="struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</h2> |
789 | <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"> |
790 | <div id="code_ev_timer_code_relative_and_opti-2"> |
445 | <p>Timer watchers are simple relative timers that generate an event after a |
791 | <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> |
792 | 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 |
793 | <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 |
794 | 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 |
795 | time, it will still time out after (roughly) and hour. "Roughly" because |
450 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
796 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
451 | monotonic clock option helps a lot here).</p> |
797 | monotonic clock option helps a lot here).</p> |
|
|
798 | <p>The relative timeouts are calculated relative to the <code>ev_now ()</code> |
|
|
799 | time. This is usually the right thing as this timestamp refers to the time |
|
|
800 | of the event triggering whatever timeout you are modifying/starting. If |
|
|
801 | you suspect event processing to be delayed and you <i>need</i> to base the timeout |
|
|
802 | on the current time, use something like this to adjust for this:</p> |
|
|
803 | <pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
804 | |
|
|
805 | </pre> |
|
|
806 | <p>The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
807 | but if multiple timers become ready during the same loop iteration then |
|
|
808 | order of execution is undefined.</p> |
452 | <dl> |
809 | <dl> |
453 | <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> |
810 | <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> |
811 | <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> |
455 | <dd> |
812 | <dd> |
456 | <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is |
813 | <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 |
815 | timer will automatically be configured to trigger again <code>repeat</code> seconds |
459 | later, again, and again, until stopped manually.</p> |
816 | 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 |
817 | <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 |
818 | 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 |
819 | 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 |
820 | 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> |
821 | timer will not fire more than once per event loop iteration.</p> |
465 | </dd> |
822 | </dd> |
466 | <dt>ev_timer_again (loop)</dt> |
823 | <dt>ev_timer_again (loop)</dt> |
467 | <dd> |
824 | <dd> |
468 | <p>This will act as if the timer timed out and restart it again if it is |
825 | <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> |
829 | 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 |
830 | <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 |
831 | 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 |
832 | 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 |
833 | 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 |
834 | 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 |
835 | 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 |
836 | 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> |
837 | the timer, and again will automatically restart it if need be.</p> |
481 | </dd> |
838 | </dd> |
482 | </dl> |
839 | </dl> |
|
|
840 | <p>Example: create a timer that fires after 60 seconds.</p> |
|
|
841 | <pre> static void |
|
|
842 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
843 | { |
|
|
844 | .. one minute over, w is actually stopped right here |
|
|
845 | } |
483 | |
846 | |
|
|
847 | struct ev_timer mytimer; |
|
|
848 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
849 | ev_timer_start (loop, &mytimer); |
|
|
850 | |
|
|
851 | </pre> |
|
|
852 | <p>Example: create a timeout timer that times out after 10 seconds of |
|
|
853 | inactivity.</p> |
|
|
854 | <pre> static void |
|
|
855 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
856 | { |
|
|
857 | .. ten seconds without any activity |
|
|
858 | } |
|
|
859 | |
|
|
860 | struct ev_timer mytimer; |
|
|
861 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
862 | ev_timer_again (&mytimer); /* start timer */ |
|
|
863 | ev_loop (loop, 0); |
|
|
864 | |
|
|
865 | // and in some piece of code that gets executed on any "activity": |
|
|
866 | // reset the timeout to start ticking again at 10 seconds |
|
|
867 | ev_timer_again (&mytimer); |
|
|
868 | |
|
|
869 | |
|
|
870 | |
|
|
871 | |
|
|
872 | </pre> |
|
|
873 | |
484 | </div> |
874 | </div> |
485 | <h2 id="ev_periodic">ev_periodic</h2> |
875 | <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"> |
876 | <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 |
877 | <p>Periodic watchers are also timers of a kind, but they are very versatile |
488 | (and unfortunately a bit complex).</p> |
878 | (and unfortunately a bit complex).</p> |
489 | <p>Unlike ev_timer's, they are not based on real time (or relative time) |
879 | <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 |
880 | 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 |
881 | 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 () |
882 | periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () |
493 | + 10.>) and then reset your system clock to the last year, then it will |
883 | + 10.</code>) 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 |
884 | 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 |
885 | roughly 10 seconds later and of course not if you reset your system time |
496 | again).</p> |
886 | again).</p> |
497 | <p>They can also be used to implement vastly more complex timers, such as |
887 | <p>They can also be used to implement vastly more complex timers, such as |
498 | triggering an event on eahc midnight, local time.</p> |
888 | triggering an event on eahc midnight, local time.</p> |
|
|
889 | <p>As with timers, the callback is guarenteed to be invoked only when the |
|
|
890 | time (<code>at</code>) has been passed, but if multiple periodic timers become ready |
|
|
891 | during the same loop iteration then order of execution is undefined.</p> |
499 | <dl> |
892 | <dl> |
500 | <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> |
893 | <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> |
894 | <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> |
502 | <dd> |
895 | <dd> |
503 | <p>Lots of arguments, lets sort it out... There are basically three modes of |
896 | <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> |
897 | operation, and we will explain them from simplest to complex:</p> |
505 | |
|
|
506 | |
|
|
507 | |
|
|
508 | |
|
|
509 | <p> |
898 | <p> |
510 | <dl> |
899 | <dl> |
511 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
900 | <dt>* absolute timer (interval = reschedule_cb = 0)</dt> |
512 | <dd> |
901 | <dd> |
513 | <p>In this configuration the watcher triggers an event at the wallclock time |
902 | <p>In this configuration the watcher triggers an event at the wallclock time |
… | |
… | |
525 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
914 | <pre> ev_periodic_set (&periodic, 0., 3600., 0); |
526 | |
915 | |
527 | </pre> |
916 | </pre> |
528 | <p>This doesn't mean there will always be 3600 seconds in between triggers, |
917 | <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 |
918 | 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 |
919 | full hour (UTC), or more correctly, when the system time is evenly divisible |
531 | by 3600.</p> |
920 | by 3600.</p> |
532 | <p>Another way to think about it (for the mathematically inclined) is that |
921 | <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 |
922 | <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> |
923 | time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> |
535 | </dd> |
924 | </dd> |
536 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
925 | <dt>* manual reschedule mode (reschedule_cb = callback)</dt> |
537 | <dd> |
926 | <dd> |
538 | <p>In this mode the values for <code>interval</code> and <code>at</code> are both being |
927 | <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 |
928 | ignored. Instead, each time the periodic watcher gets scheduled, the |
540 | reschedule callback will be called with the watcher as first, and the |
929 | reschedule callback will be called with the watcher as first, and the |
541 | current time as second argument.</p> |
930 | current time as second argument.</p> |
542 | <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other |
931 | <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 |
932 | 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> |
933 | return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
934 | starting a prepare watcher).</p> |
545 | <p>Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
935 | <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
546 | ev_tstamp now)>, e.g.:</p> |
936 | ev_tstamp now)</code>, e.g.:</p> |
547 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
937 | <pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
548 | { |
938 | { |
549 | return now + 60.; |
939 | return now + 60.; |
550 | } |
940 | } |
551 | |
941 | |
552 | </pre> |
942 | </pre> |
553 | <p>It must return the next time to trigger, based on the passed time value |
943 | <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 |
944 | (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 |
945 | will usually be called just before the callback will be triggered, but |
556 | might be called at other times, too.</p> |
946 | might be called at other times, too.</p> |
|
|
947 | <p>NOTE: <i>This callback must always return a time that is later than the |
|
|
948 | 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 |
949 | <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 |
950 | 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 |
951 | 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> |
952 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
953 | reason I omitted it as an example).</p> |
561 | </dd> |
954 | </dd> |
562 | </dl> |
955 | </dl> |
563 | </p> |
956 | </p> |
564 | </dd> |
957 | </dd> |
565 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
958 | <dt>ev_periodic_again (loop, ev_periodic *)</dt> |
… | |
… | |
568 | when you changed some parameters or the reschedule callback would return |
961 | when you changed some parameters or the reschedule callback would return |
569 | a different time than the last time it was called (e.g. in a crond like |
962 | a different time than the last time it was called (e.g. in a crond like |
570 | program when the crontabs have changed).</p> |
963 | program when the crontabs have changed).</p> |
571 | </dd> |
964 | </dd> |
572 | </dl> |
965 | </dl> |
|
|
966 | <p>Example: call a callback every hour, or, more precisely, whenever the |
|
|
967 | system clock is divisible by 3600. The callback invocation times have |
|
|
968 | potentially a lot of jittering, but good long-term stability.</p> |
|
|
969 | <pre> static void |
|
|
970 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
971 | { |
|
|
972 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
973 | } |
573 | |
974 | |
|
|
975 | struct ev_periodic hourly_tick; |
|
|
976 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
977 | ev_periodic_start (loop, &hourly_tick); |
|
|
978 | |
|
|
979 | </pre> |
|
|
980 | <p>Example: the same as above, but use a reschedule callback to do it:</p> |
|
|
981 | <pre> #include <math.h> |
|
|
982 | |
|
|
983 | static ev_tstamp |
|
|
984 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
985 | { |
|
|
986 | return fmod (now, 3600.) + 3600.; |
|
|
987 | } |
|
|
988 | |
|
|
989 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
990 | |
|
|
991 | </pre> |
|
|
992 | <p>Example: call a callback every hour, starting now:</p> |
|
|
993 | <pre> struct ev_periodic hourly_tick; |
|
|
994 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
995 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
996 | ev_periodic_start (loop, &hourly_tick); |
|
|
997 | |
|
|
998 | |
|
|
999 | |
|
|
1000 | |
|
|
1001 | </pre> |
|
|
1002 | |
574 | </div> |
1003 | </div> |
575 | <h2 id="ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</h2> |
1004 | <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"> |
1005 | <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 |
1006 | <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 |
1007 | 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 |
1008 | will try it's best to deliver signals synchronously, i.e. as part of the |
580 | normal event processing, like any other event.</p> |
1009 | normal event processing, like any other event.</p> |
581 | <p>You cna configure as many watchers as you like per signal. Only when the |
1010 | <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 |
1011 | 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 |
1012 | 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 |
1013 | 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 |
1014 | 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> |
1015 | SIG_DFL (regardless of what it was set to before).</p> |
… | |
… | |
591 | <p>Configures the watcher to trigger on the given signal number (usually one |
1020 | <p>Configures the watcher to trigger on the given signal number (usually one |
592 | of the <code>SIGxxx</code> constants).</p> |
1021 | of the <code>SIGxxx</code> constants).</p> |
593 | </dd> |
1022 | </dd> |
594 | </dl> |
1023 | </dl> |
595 | |
1024 | |
|
|
1025 | |
|
|
1026 | |
|
|
1027 | |
|
|
1028 | |
596 | </div> |
1029 | </div> |
597 | <h2 id="ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</h2> |
1030 | <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"> |
1031 | <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 |
1032 | <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> |
1033 | some child status changes (most typically when a child of yours dies).</p> |
601 | <dl> |
1034 | <dl> |
602 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
1035 | <dt>ev_child_init (ev_child *, callback, int pid)</dt> |
603 | <dt>ev_child_set (ev_child *, int pid)</dt> |
1036 | <dt>ev_child_set (ev_child *, int pid)</dt> |
604 | <dd> |
1037 | <dd> |
605 | <p>Configures the watcher to wait for status changes of process <code>pid</code> (or |
1038 | <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 |
1039 | <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 |
1040 | 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 |
1041 | the status word (use the macros from <code>sys/wait.h</code> and see your systems |
|
|
1042 | <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> |
1043 | process causing the status change.</p> |
610 | </dd> |
1044 | </dd> |
611 | </dl> |
1045 | </dl> |
|
|
1046 | <p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> |
|
|
1047 | <pre> static void |
|
|
1048 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1049 | { |
|
|
1050 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1051 | } |
612 | |
1052 | |
|
|
1053 | struct ev_signal signal_watcher; |
|
|
1054 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1055 | ev_signal_start (loop, &sigint_cb); |
|
|
1056 | |
|
|
1057 | |
|
|
1058 | |
|
|
1059 | |
|
|
1060 | </pre> |
|
|
1061 | |
613 | </div> |
1062 | </div> |
614 | <h2 id="ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</h2> |
1063 | <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"> |
1064 | <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 |
1065 | <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 |
1066 | (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 |
1067 | 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 |
1068 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
1069 | watchers are being called again and again, once per event loop iteration - |
620 | stopped, that is, or your process receives more events.</p> |
1070 | until stopped, that is, or your process receives more events and becomes |
|
|
1071 | busy.</p> |
621 | <p>The most noteworthy effect is that as long as any idle watchers are |
1072 | <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> |
1073 | 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 |
1074 | <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 |
1075 | effect on its own sometimes), idle watchers are a good place to do |
625 | "pseudo-background processing", or delay processing stuff to after the |
1076 | "pseudo-background processing", or delay processing stuff to after the |
… | |
… | |
630 | <p>Initialises and configures the idle watcher - it has no parameters of any |
1081 | <p>Initialises and configures the idle watcher - it has no parameters of any |
631 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
1082 | kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, |
632 | believe me.</p> |
1083 | believe me.</p> |
633 | </dd> |
1084 | </dd> |
634 | </dl> |
1085 | </dl> |
|
|
1086 | <p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the |
|
|
1087 | callback, free it. Alos, use no error checking, as usual.</p> |
|
|
1088 | <pre> static void |
|
|
1089 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1090 | { |
|
|
1091 | free (w); |
|
|
1092 | // now do something you wanted to do when the program has |
|
|
1093 | // no longer asnything immediate to do. |
|
|
1094 | } |
635 | |
1095 | |
|
|
1096 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1097 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1098 | ev_idle_start (loop, idle_cb); |
|
|
1099 | |
|
|
1100 | |
|
|
1101 | |
|
|
1102 | |
|
|
1103 | </pre> |
|
|
1104 | |
636 | </div> |
1105 | </div> |
637 | <h2 id="prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</h2> |
1106 | <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"> |
1107 | <div id="code_ev_prepare_code_and_code_ev_che-2"> |
639 | <p>Prepare and check watchers usually (but not always) are used in |
1108 | <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 |
1109 | prepare watchers get invoked before the process blocks and check watchers |
641 | watchers afterwards.</p> |
1110 | afterwards.</p> |
642 | <p>Their main purpose is to integrate other event mechanisms into libev. This |
1111 | <p>Their main purpose is to integrate other event mechanisms into libev and |
643 | could be used, for example, to track variable changes, implement your own |
1112 | their use is somewhat advanced. This could be used, for example, to track |
644 | watchers, integrate net-snmp or a coroutine library and lots more.</p> |
1113 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1114 | coroutine library and lots more.</p> |
645 | <p>This is done by examining in each prepare call which file descriptors need |
1115 | <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 |
1116 | 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 |
1117 | 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 |
1118 | 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) |
1119 | any events that occured (by checking the pending status of all watchers |
650 | and call back into the library.</p> |
1120 | and stopping them) and call back into the library. The I/O and timer |
|
|
1121 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
1122 | because you never know, you know?).</p> |
651 | <p>As another example, the perl Coro module uses these hooks to integrate |
1123 | <p>As another example, the Perl Coro module uses these hooks to integrate |
652 | coroutines into libev programs, by yielding to other active coroutines |
1124 | coroutines into libev programs, by yielding to other active coroutines |
653 | during each prepare and only letting the process block if no coroutines |
1125 | during each prepare and only letting the process block if no coroutines |
654 | are ready to run.</p> |
1126 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
1127 | with priority higher than or equal to the event loop and one coroutine |
|
|
1128 | of lower priority, but only once, using idle watchers to keep the event |
|
|
1129 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
1130 | low-priority coroutines to idle/background tasks).</p> |
655 | <dl> |
1131 | <dl> |
656 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
1132 | <dt>ev_prepare_init (ev_prepare *, callback)</dt> |
657 | <dt>ev_check_init (ev_check *, callback)</dt> |
1133 | <dt>ev_check_init (ev_check *, callback)</dt> |
658 | <dd> |
1134 | <dd> |
659 | <p>Initialises and configures the prepare or check watcher - they have no |
1135 | <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> |
1136 | 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> |
1137 | macros, but using them is utterly, utterly and completely pointless.</p> |
662 | </dd> |
1138 | </dd> |
663 | </dl> |
1139 | </dl> |
|
|
1140 | <p>Example: *TODO*.</p> |
|
|
1141 | |
|
|
1142 | |
|
|
1143 | |
|
|
1144 | |
|
|
1145 | |
|
|
1146 | </div> |
|
|
1147 | <h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> |
|
|
1148 | <div id="code_ev_embed_code_when_one_backend_-2"> |
|
|
1149 | <p>This is a rather advanced watcher type that lets you embed one event loop |
|
|
1150 | into another (currently only <code>ev_io</code> events are supported in the embedded |
|
|
1151 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1152 | fashion and must not be used).</p> |
|
|
1153 | <p>There are primarily two reasons you would want that: work around bugs and |
|
|
1154 | prioritise I/O.</p> |
|
|
1155 | <p>As an example for a bug workaround, the kqueue backend might only support |
|
|
1156 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1157 | still want to make use of it because you have many sockets and it scales |
|
|
1158 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1159 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1160 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1161 | at least you can use both at what they are best.</p> |
|
|
1162 | <p>As for prioritising I/O: rarely you have the case where some fds have |
|
|
1163 | to be watched and handled very quickly (with low latency), and even |
|
|
1164 | priorities and idle watchers might have too much overhead. In this case |
|
|
1165 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1166 | a second one, and embed the second one in the first.</p> |
|
|
1167 | <p>As long as the watcher is active, the callback will be invoked every time |
|
|
1168 | there might be events pending in the embedded loop. The callback must then |
|
|
1169 | call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke |
|
|
1170 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1171 | loop strictly lower priority for example). You can also set the callback |
|
|
1172 | to <code>0</code>, in which case the embed watcher will automatically execute the |
|
|
1173 | embedded loop sweep.</p> |
|
|
1174 | <p>As long as the watcher is started it will automatically handle events. The |
|
|
1175 | callback will be invoked whenever some events have been handled. You can |
|
|
1176 | set the callback to <code>0</code> to avoid having to specify one if you are not |
|
|
1177 | interested in that.</p> |
|
|
1178 | <p>Also, there have not currently been made special provisions for forking: |
|
|
1179 | when you fork, you not only have to call <code>ev_loop_fork</code> on both loops, |
|
|
1180 | but you will also have to stop and restart any <code>ev_embed</code> watchers |
|
|
1181 | yourself.</p> |
|
|
1182 | <p>Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1183 | <code>ev_embeddable_backends</code> are, which, unfortunately, does not include any |
|
|
1184 | portable one.</p> |
|
|
1185 | <p>So when you want to use this feature you will always have to be prepared |
|
|
1186 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1187 | this is to have a separate variables for your embeddable loop, try to |
|
|
1188 | create it, and if that fails, use the normal loop for everything:</p> |
|
|
1189 | <pre> struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1190 | struct ev_loop *loop_lo = 0; |
|
|
1191 | struct ev_embed embed; |
|
|
1192 | |
|
|
1193 | // see if there is a chance of getting one that works |
|
|
1194 | // (remember that a flags value of 0 means autodetection) |
|
|
1195 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1196 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1197 | : 0; |
|
|
1198 | |
|
|
1199 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1200 | if (loop_lo) |
|
|
1201 | { |
|
|
1202 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1203 | ev_embed_start (loop_hi, &embed); |
|
|
1204 | } |
|
|
1205 | else |
|
|
1206 | loop_lo = loop_hi; |
|
|
1207 | |
|
|
1208 | </pre> |
|
|
1209 | <dl> |
|
|
1210 | <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1211 | <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> |
|
|
1212 | <dd> |
|
|
1213 | <p>Configures the watcher to embed the given loop, which must be |
|
|
1214 | embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be |
|
|
1215 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1216 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1217 | if you do not want thta, you need to temporarily stop the embed watcher).</p> |
|
|
1218 | </dd> |
|
|
1219 | <dt>ev_embed_sweep (loop, ev_embed *)</dt> |
|
|
1220 | <dd> |
|
|
1221 | <p>Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1222 | similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most |
|
|
1223 | apropriate way for embedded loops.</p> |
|
|
1224 | </dd> |
|
|
1225 | </dl> |
|
|
1226 | |
|
|
1227 | |
|
|
1228 | |
|
|
1229 | |
664 | |
1230 | |
665 | </div> |
1231 | </div> |
666 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1232 | <h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> |
667 | <div id="OTHER_FUNCTIONS_CONTENT"> |
1233 | <div id="OTHER_FUNCTIONS_CONTENT"> |
668 | <p>There are some other fucntions of possible interest. Described. Here. Now.</p> |
1234 | <p>There are some other functions of possible interest. Described. Here. Now.</p> |
669 | <dl> |
1235 | <dl> |
670 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
1236 | <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> |
671 | <dd> |
1237 | <dd> |
672 | <p>This function combines a simple timer and an I/O watcher, calls your |
1238 | <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 |
1239 | 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 |
1240 | 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 |
1241 | or timeout without having to allocate/configure/start/stop/free one or |
676 | more watchers yourself.</p> |
1242 | 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 |
1243 | <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 |
1244 | is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and |
679 | will be craeted and started.</p> |
1245 | <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 |
1246 | <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 |
1247 | started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and |
682 | = 0) will be started.</p> |
1248 | repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of |
|
|
1249 | dubious value.</p> |
683 | <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and |
1250 | <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, |
1251 | 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> |
1252 | <code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> |
|
|
1253 | value passed to <code>ev_once</code>:</p> |
686 | <pre> static void stdin_ready (int revents, void *arg) |
1254 | <pre> static void stdin_ready (int revents, void *arg) |
687 | { |
1255 | { |
688 | if (revents & EV_TIMEOUT) |
1256 | if (revents & EV_TIMEOUT) |
689 | /* doh, nothing entered */ |
1257 | /* doh, nothing entered */; |
690 | else if (revents & EV_READ) |
1258 | else if (revents & EV_READ) |
691 | /* stdin might have data for us, joy! */ |
1259 | /* stdin might have data for us, joy! */; |
692 | } |
1260 | } |
693 | |
1261 | |
694 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
1262 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
695 | |
1263 | |
696 | </pre> |
1264 | </pre> |
697 | </dd> |
1265 | </dd> |
698 | <dt>ev_feed_event (loop, watcher, int events)</dt> |
1266 | <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt> |
699 | <dd> |
1267 | <dd> |
700 | <p>Feeds the given event set into the event loop, as if the specified event |
1268 | <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 |
1269 | had happened for the specified watcher (which must be a pointer to an |
702 | initialised but not necessarily active event watcher).</p> |
1270 | initialised but not necessarily started event watcher).</p> |
703 | </dd> |
1271 | </dd> |
704 | <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> |
1272 | <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt> |
705 | <dd> |
1273 | <dd> |
706 | <p>Feed an event on the given fd, as if a file descriptor backend detected it.</p> |
1274 | <p>Feed an event on the given fd, as if a file descriptor backend detected |
|
|
1275 | the given events it.</p> |
707 | </dd> |
1276 | </dd> |
708 | <dt>ev_feed_signal_event (loop, int signum)</dt> |
1277 | <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt> |
709 | <dd> |
1278 | <dd> |
710 | <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> |
1279 | <p>Feed an event as if the given signal occured (<code>loop</code> must be the default |
|
|
1280 | loop!).</p> |
711 | </dd> |
1281 | </dd> |
712 | </dl> |
1282 | </dl> |
|
|
1283 | |
|
|
1284 | |
|
|
1285 | |
|
|
1286 | |
|
|
1287 | |
|
|
1288 | </div> |
|
|
1289 | <h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
1290 | <div id="LIBEVENT_EMULATION_CONTENT"> |
|
|
1291 | <p>Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
1292 | emulate the internals of libevent, so here are some usage hints:</p> |
|
|
1293 | <dl> |
|
|
1294 | <dt>* Use it by including <event.h>, as usual.</dt> |
|
|
1295 | <dt>* The following members are fully supported: ev_base, ev_callback, |
|
|
1296 | ev_arg, ev_fd, ev_res, ev_events.</dt> |
|
|
1297 | <dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
1298 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
1299 | it a private API).</dt> |
|
|
1300 | <dt>* Priorities are not currently supported. Initialising priorities |
|
|
1301 | will fail and all watchers will have the same priority, even though there |
|
|
1302 | is an ev_pri field.</dt> |
|
|
1303 | <dt>* Other members are not supported.</dt> |
|
|
1304 | <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need |
|
|
1305 | to use the libev header file and library.</dt> |
|
|
1306 | </dl> |
|
|
1307 | |
|
|
1308 | </div> |
|
|
1309 | <h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> |
|
|
1310 | <div id="C_SUPPORT_CONTENT"> |
|
|
1311 | <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1312 | you to use some convinience methods to start/stop watchers and also change |
|
|
1313 | the callback model to a model using method callbacks on objects.</p> |
|
|
1314 | <p>To use it,</p> |
|
|
1315 | <pre> #include <ev++.h> |
|
|
1316 | |
|
|
1317 | </pre> |
|
|
1318 | <p>(it is not installed by default). This automatically includes <cite>ev.h</cite> |
|
|
1319 | and puts all of its definitions (many of them macros) into the global |
|
|
1320 | namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> |
|
|
1321 | <p>It should support all the same embedding options as <cite>ev.h</cite>, most notably |
|
|
1322 | <code>EV_MULTIPLICITY</code>.</p> |
|
|
1323 | <p>Here is a list of things available in the <code>ev</code> namespace:</p> |
|
|
1324 | <dl> |
|
|
1325 | <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> |
|
|
1326 | <dd> |
|
|
1327 | <p>These are just enum values with the same values as the <code>EV_READ</code> etc. |
|
|
1328 | macros from <cite>ev.h</cite>.</p> |
|
|
1329 | </dd> |
|
|
1330 | <dt><code>ev::tstamp</code>, <code>ev::now</code></dt> |
|
|
1331 | <dd> |
|
|
1332 | <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p> |
|
|
1333 | </dd> |
|
|
1334 | <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt> |
|
|
1335 | <dd> |
|
|
1336 | <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of |
|
|
1337 | the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code> |
|
|
1338 | which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro |
|
|
1339 | defines by many implementations.</p> |
|
|
1340 | <p>All of those classes have these methods:</p> |
|
|
1341 | <p> |
|
|
1342 | <dl> |
|
|
1343 | <dt>ev::TYPE::TYPE (object *, object::method *)</dt> |
|
|
1344 | <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> |
|
|
1345 | <dt>ev::TYPE::~TYPE</dt> |
|
|
1346 | <dd> |
|
|
1347 | <p>The constructor takes a pointer to an object and a method pointer to |
|
|
1348 | the event handler callback to call in this class. The constructor calls |
|
|
1349 | <code>ev_init</code> for you, which means you have to call the <code>set</code> method |
|
|
1350 | before starting it. If you do not specify a loop then the constructor |
|
|
1351 | automatically associates the default loop with this watcher.</p> |
|
|
1352 | <p>The destructor automatically stops the watcher if it is active.</p> |
|
|
1353 | </dd> |
|
|
1354 | <dt>w->set (struct ev_loop *)</dt> |
|
|
1355 | <dd> |
|
|
1356 | <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only |
|
|
1357 | do this when the watcher is inactive (and not pending either).</p> |
|
|
1358 | </dd> |
|
|
1359 | <dt>w->set ([args])</dt> |
|
|
1360 | <dd> |
|
|
1361 | <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be |
|
|
1362 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1363 | automatically stopped and restarted.</p> |
|
|
1364 | </dd> |
|
|
1365 | <dt>w->start ()</dt> |
|
|
1366 | <dd> |
|
|
1367 | <p>Starts the watcher. Note that there is no <code>loop</code> argument as the |
|
|
1368 | constructor already takes the loop.</p> |
|
|
1369 | </dd> |
|
|
1370 | <dt>w->stop ()</dt> |
|
|
1371 | <dd> |
|
|
1372 | <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> |
|
|
1373 | </dd> |
|
|
1374 | <dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt> |
|
|
1375 | <dd> |
|
|
1376 | <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding |
|
|
1377 | <code>ev_TYPE_again</code> function.</p> |
|
|
1378 | </dd> |
|
|
1379 | <dt>w->sweep () <code>ev::embed</code> only</dt> |
|
|
1380 | <dd> |
|
|
1381 | <p>Invokes <code>ev_embed_sweep</code>.</p> |
|
|
1382 | </dd> |
|
|
1383 | </dl> |
|
|
1384 | </p> |
|
|
1385 | </dd> |
|
|
1386 | </dl> |
|
|
1387 | <p>Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1388 | the constructor.</p> |
|
|
1389 | <pre> class myclass |
|
|
1390 | { |
|
|
1391 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1392 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1393 | |
|
|
1394 | myclass (); |
|
|
1395 | } |
|
|
1396 | |
|
|
1397 | myclass::myclass (int fd) |
|
|
1398 | : io (this, &myclass::io_cb), |
|
|
1399 | idle (this, &myclass::idle_cb) |
|
|
1400 | { |
|
|
1401 | io.start (fd, ev::READ); |
|
|
1402 | } |
|
|
1403 | |
|
|
1404 | </pre> |
713 | |
1405 | |
714 | </div> |
1406 | </div> |
715 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
1407 | <h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> |
716 | <div id="AUTHOR_CONTENT"> |
1408 | <div id="AUTHOR_CONTENT"> |
717 | <p>Marc Lehmann <libev@schmorp.de>.</p> |
1409 | <p>Marc Lehmann <libev@schmorp.de>.</p> |