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2 | |
2 | |
3 | libev - a high performance full-featured event loop written in C |
3 | libev - a high performance full-featured event loop written in C |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
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7 | /* this is the only header you need */ |
7 | #include <ev.h> |
8 | #include <ev.h> |
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9 | |
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10 | /* what follows is a fully working example program */ |
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11 | ev_io stdin_watcher; |
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12 | ev_timer timeout_watcher; |
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13 | |
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14 | /* called when data readable on stdin */ |
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15 | static void |
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16 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
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17 | { |
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18 | /* puts ("stdin ready"); */ |
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19 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
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20 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
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21 | } |
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22 | |
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23 | static void |
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24 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
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25 | { |
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26 | /* puts ("timeout"); */ |
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27 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
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28 | } |
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29 | |
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30 | int |
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31 | main (void) |
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32 | { |
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33 | struct ev_loop *loop = ev_default_loop (0); |
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34 | |
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35 | /* initialise an io watcher, then start it */ |
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36 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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37 | ev_io_start (loop, &stdin_watcher); |
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38 | |
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39 | /* simple non-repeating 5.5 second timeout */ |
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40 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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41 | ev_timer_start (loop, &timeout_watcher); |
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42 | |
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43 | /* loop till timeout or data ready */ |
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44 | ev_loop (loop, 0); |
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45 | |
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46 | return 0; |
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47 | } |
8 | |
48 | |
9 | =head1 DESCRIPTION |
49 | =head1 DESCRIPTION |
10 | |
50 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
51 | Libev is an event loop: you register interest in certain events (such as a |
12 | file descriptor being readable or a timeout occuring), and it will manage |
52 | file descriptor being readable or a timeout occuring), and it will manage |
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39 | F<README.embed> in the libev distribution. If libev was configured without |
79 | F<README.embed> in the libev distribution. If libev was configured without |
40 | support for multiple event loops, then all functions taking an initial |
80 | support for multiple event loops, then all functions taking an initial |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
81 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
42 | will not have this argument. |
82 | will not have this argument. |
43 | |
83 | |
44 | =head1 TIME AND OTHER GLOBAL FUNCTIONS |
84 | =head1 TIME REPRESENTATION |
45 | |
85 | |
46 | Libev represents time as a single floating point number, representing the |
86 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
87 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
88 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
89 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
90 | to the C<double> type in C, and when you need to do any calculations on |
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91 | it, you should treat it as such. |
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92 | |
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93 | =head1 GLOBAL FUNCTIONS |
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94 | |
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95 | These functions can be called anytime, even before initialising the |
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96 | library in any way. |
51 | |
97 | |
52 | =over 4 |
98 | =over 4 |
53 | |
99 | |
54 | =item ev_tstamp ev_time () |
100 | =item ev_tstamp ev_time () |
55 | |
101 | |
56 | Returns the current time as libev would use it. |
102 | Returns the current time as libev would use it. Please note that the |
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103 | C<ev_now> function is usually faster and also often returns the timestamp |
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104 | you actually want to know. |
57 | |
105 | |
58 | =item int ev_version_major () |
106 | =item int ev_version_major () |
59 | |
107 | |
60 | =item int ev_version_minor () |
108 | =item int ev_version_minor () |
61 | |
109 | |
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68 | Usually, it's a good idea to terminate if the major versions mismatch, |
116 | Usually, it's a good idea to terminate if the major versions mismatch, |
69 | as this indicates an incompatible change. Minor versions are usually |
117 | as this indicates an incompatible change. Minor versions are usually |
70 | compatible to older versions, so a larger minor version alone is usually |
118 | compatible to older versions, so a larger minor version alone is usually |
71 | not a problem. |
119 | not a problem. |
72 | |
120 | |
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121 | Example: make sure we haven't accidentally been linked against the wrong |
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122 | version: |
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123 | |
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124 | assert (("libev version mismatch", |
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125 | ev_version_major () == EV_VERSION_MAJOR |
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126 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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127 | |
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128 | =item unsigned int ev_supported_backends () |
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129 | |
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130 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
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131 | value) compiled into this binary of libev (independent of their |
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132 | availability on the system you are running on). See C<ev_default_loop> for |
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133 | a description of the set values. |
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134 | |
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135 | Example: make sure we have the epoll method, because yeah this is cool and |
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136 | a must have and can we have a torrent of it please!!!11 |
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137 | |
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138 | assert (("sorry, no epoll, no sex", |
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139 | ev_supported_backends () & EVBACKEND_EPOLL)); |
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140 | |
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141 | =item unsigned int ev_recommended_backends () |
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142 | |
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143 | Return the set of all backends compiled into this binary of libev and also |
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144 | recommended for this platform. This set is often smaller than the one |
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145 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
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146 | most BSDs and will not be autodetected unless you explicitly request it |
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147 | (assuming you know what you are doing). This is the set of backends that |
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148 | libev will probe for if you specify no backends explicitly. |
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149 | |
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150 | =item unsigned int ev_embeddable_backends () |
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151 | |
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152 | Returns the set of backends that are embeddable in other event loops. This |
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153 | is the theoretical, all-platform, value. To find which backends |
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154 | might be supported on the current system, you would need to look at |
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155 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
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156 | recommended ones. |
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157 | |
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158 | See the description of C<ev_embed> watchers for more info. |
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159 | |
73 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
160 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
74 | |
161 | |
75 | Sets the allocation function to use (the prototype is similar to the |
162 | Sets the allocation function to use (the prototype and semantics are |
76 | realloc C function, the semantics are identical). It is used to allocate |
163 | identical to the realloc C function). It is used to allocate and free |
77 | and free memory (no surprises here). If it returns zero when memory |
164 | memory (no surprises here). If it returns zero when memory needs to be |
78 | needs to be allocated, the library might abort or take some potentially |
165 | allocated, the library might abort or take some potentially destructive |
79 | destructive action. The default is your system realloc function. |
166 | action. The default is your system realloc function. |
80 | |
167 | |
81 | You could override this function in high-availability programs to, say, |
168 | You could override this function in high-availability programs to, say, |
82 | free some memory if it cannot allocate memory, to use a special allocator, |
169 | free some memory if it cannot allocate memory, to use a special allocator, |
83 | or even to sleep a while and retry until some memory is available. |
170 | or even to sleep a while and retry until some memory is available. |
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171 | |
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172 | Example: replace the libev allocator with one that waits a bit and then |
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173 | retries: better than mine). |
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174 | |
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175 | static void * |
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176 | persistent_realloc (void *ptr, size_t size) |
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177 | { |
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178 | for (;;) |
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179 | { |
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180 | void *newptr = realloc (ptr, size); |
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181 | |
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182 | if (newptr) |
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183 | return newptr; |
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184 | |
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185 | sleep (60); |
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186 | } |
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187 | } |
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188 | |
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189 | ... |
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190 | ev_set_allocator (persistent_realloc); |
84 | |
191 | |
85 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
192 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
86 | |
193 | |
87 | Set the callback function to call on a retryable syscall error (such |
194 | Set the callback function to call on a retryable syscall error (such |
88 | as failed select, poll, epoll_wait). The message is a printable string |
195 | as failed select, poll, epoll_wait). The message is a printable string |
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90 | callback is set, then libev will expect it to remedy the sitution, no |
197 | callback is set, then libev will expect it to remedy the sitution, no |
91 | matter what, when it returns. That is, libev will generally retry the |
198 | matter what, when it returns. That is, libev will generally retry the |
92 | requested operation, or, if the condition doesn't go away, do bad stuff |
199 | requested operation, or, if the condition doesn't go away, do bad stuff |
93 | (such as abort). |
200 | (such as abort). |
94 | |
201 | |
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202 | Example: do the same thing as libev does internally: |
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203 | |
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204 | static void |
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205 | fatal_error (const char *msg) |
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206 | { |
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207 | perror (msg); |
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208 | abort (); |
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209 | } |
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210 | |
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211 | ... |
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212 | ev_set_syserr_cb (fatal_error); |
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213 | |
95 | =back |
214 | =back |
96 | |
215 | |
97 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
216 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
98 | |
217 | |
99 | An event loop is described by a C<struct ev_loop *>. The library knows two |
218 | An event loop is described by a C<struct ev_loop *>. The library knows two |
100 | types of such loops, the I<default> loop, which supports signals and child |
219 | types of such loops, the I<default> loop, which supports signals and child |
101 | events, and dynamically created loops which do not. |
220 | events, and dynamically created loops which do not. |
102 | |
221 | |
103 | If you use threads, a common model is to run the default event loop |
222 | If you use threads, a common model is to run the default event loop |
104 | in your main thread (or in a separate thrad) and for each thread you |
223 | in your main thread (or in a separate thread) and for each thread you |
105 | create, you also create another event loop. Libev itself does no locking |
224 | create, you also create another event loop. Libev itself does no locking |
106 | whatsoever, so if you mix calls to the same event loop in different |
225 | whatsoever, so if you mix calls to the same event loop in different |
107 | threads, make sure you lock (this is usually a bad idea, though, even if |
226 | threads, make sure you lock (this is usually a bad idea, though, even if |
108 | done correctly, because it's hideous and inefficient). |
227 | done correctly, because it's hideous and inefficient). |
109 | |
228 | |
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112 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
231 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
113 | |
232 | |
114 | This will initialise the default event loop if it hasn't been initialised |
233 | This will initialise the default event loop if it hasn't been initialised |
115 | yet and return it. If the default loop could not be initialised, returns |
234 | yet and return it. If the default loop could not be initialised, returns |
116 | false. If it already was initialised it simply returns it (and ignores the |
235 | false. If it already was initialised it simply returns it (and ignores the |
117 | flags). |
236 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
118 | |
237 | |
119 | If you don't know what event loop to use, use the one returned from this |
238 | If you don't know what event loop to use, use the one returned from this |
120 | function. |
239 | function. |
121 | |
240 | |
122 | The flags argument can be used to specify special behaviour or specific |
241 | The flags argument can be used to specify special behaviour or specific |
123 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO). |
242 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
124 | |
243 | |
125 | It supports the following flags: |
244 | The following flags are supported: |
126 | |
245 | |
127 | =over 4 |
246 | =over 4 |
128 | |
247 | |
129 | =item C<EVFLAG_AUTO> |
248 | =item C<EVFLAG_AUTO> |
130 | |
249 | |
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138 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
257 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
139 | override the flags completely if it is found in the environment. This is |
258 | override the flags completely if it is found in the environment. This is |
140 | useful to try out specific backends to test their performance, or to work |
259 | useful to try out specific backends to test their performance, or to work |
141 | around bugs. |
260 | around bugs. |
142 | |
261 | |
143 | =item C<EVMETHOD_SELECT> (portable select backend) |
262 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
144 | |
263 | |
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264 | This is your standard select(2) backend. Not I<completely> standard, as |
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265 | libev tries to roll its own fd_set with no limits on the number of fds, |
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266 | but if that fails, expect a fairly low limit on the number of fds when |
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267 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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268 | the fastest backend for a low number of fds. |
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269 | |
145 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
270 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
146 | |
271 | |
147 | =item C<EVMETHOD_EPOLL> (linux only) |
272 | And this is your standard poll(2) backend. It's more complicated than |
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273 | select, but handles sparse fds better and has no artificial limit on the |
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274 | number of fds you can use (except it will slow down considerably with a |
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275 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
148 | |
276 | |
149 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
277 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
150 | |
278 | |
151 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
279 | For few fds, this backend is a bit little slower than poll and select, |
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280 | but it scales phenomenally better. While poll and select usually scale like |
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281 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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282 | either O(1) or O(active_fds). |
152 | |
283 | |
153 | =item C<EVMETHOD_PORT> (solaris 10 only) |
284 | While stopping and starting an I/O watcher in the same iteration will |
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285 | result in some caching, there is still a syscall per such incident |
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286 | (because the fd could point to a different file description now), so its |
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287 | best to avoid that. Also, dup()ed file descriptors might not work very |
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288 | well if you register events for both fds. |
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289 | |
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290 | Please note that epoll sometimes generates spurious notifications, so you |
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291 | need to use non-blocking I/O or other means to avoid blocking when no data |
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292 | (or space) is available. |
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293 | |
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294 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
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295 | |
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296 | Kqueue deserves special mention, as at the time of this writing, it |
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297 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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298 | anything but sockets and pipes, except on Darwin, where of course its |
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299 | completely useless). For this reason its not being "autodetected" |
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300 | unless you explicitly specify it explicitly in the flags (i.e. using |
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301 | C<EVBACKEND_KQUEUE>). |
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302 | |
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303 | It scales in the same way as the epoll backend, but the interface to the |
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304 | kernel is more efficient (which says nothing about its actual speed, of |
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305 | course). While starting and stopping an I/O watcher does not cause an |
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306 | extra syscall as with epoll, it still adds up to four event changes per |
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307 | incident, so its best to avoid that. |
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308 | |
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309 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
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310 | |
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311 | This is not implemented yet (and might never be). |
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312 | |
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313 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
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314 | |
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315 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
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316 | it's really slow, but it still scales very well (O(active_fds)). |
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317 | |
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318 | Please note that solaris ports can result in a lot of spurious |
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319 | notifications, so you need to use non-blocking I/O or other means to avoid |
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320 | blocking when no data (or space) is available. |
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321 | |
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322 | =item C<EVBACKEND_ALL> |
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323 | |
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324 | Try all backends (even potentially broken ones that wouldn't be tried |
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325 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
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326 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
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327 | |
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328 | =back |
154 | |
329 | |
155 | If one or more of these are ored into the flags value, then only these |
330 | If one or more of these are ored into the flags value, then only these |
156 | backends will be tried (in the reverse order as given here). If one are |
331 | backends will be tried (in the reverse order as given here). If none are |
157 | specified, any backend will do. |
332 | specified, most compiled-in backend will be tried, usually in reverse |
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333 | order of their flag values :) |
158 | |
334 | |
159 | =back |
335 | The most typical usage is like this: |
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336 | |
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337 | 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 | |
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340 | Restrict libev to the select and poll backends, and do not allow |
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341 | environment settings to be taken into account: |
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342 | |
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343 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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344 | |
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345 | Use whatever libev has to offer, but make sure that kqueue is used if |
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346 | available (warning, breaks stuff, best use only with your own private |
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347 | event loop and only if you know the OS supports your types of fds): |
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348 | |
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349 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
160 | |
350 | |
161 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
351 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
162 | |
352 | |
163 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
353 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
164 | always distinct from the default loop. Unlike the default loop, it cannot |
354 | always distinct from the default loop. Unlike the default loop, it cannot |
165 | handle signal and child watchers, and attempts to do so will be greeted by |
355 | handle signal and child watchers, and attempts to do so will be greeted by |
166 | undefined behaviour (or a failed assertion if assertions are enabled). |
356 | undefined behaviour (or a failed assertion if assertions are enabled). |
167 | |
357 | |
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358 | Example: try to create a event loop that uses epoll and nothing else. |
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359 | |
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360 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
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361 | if (!epoller) |
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362 | fatal ("no epoll found here, maybe it hides under your chair"); |
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363 | |
168 | =item ev_default_destroy () |
364 | =item ev_default_destroy () |
169 | |
365 | |
170 | Destroys the default loop again (frees all memory and kernel state |
366 | Destroys the default loop again (frees all memory and kernel state |
171 | etc.). This stops all registered event watchers (by not touching them in |
367 | etc.). None of the active event watchers will be stopped in the normal |
172 | any way whatsoever, although you cannot rely on this :). |
368 | sense, so e.g. C<ev_is_active> might still return true. It is your |
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369 | responsibility to either stop all watchers cleanly yoursef I<before> |
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370 | calling this function, or cope with the fact afterwards (which is usually |
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371 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
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372 | for example). |
173 | |
373 | |
174 | =item ev_loop_destroy (loop) |
374 | =item ev_loop_destroy (loop) |
175 | |
375 | |
176 | Like C<ev_default_destroy>, but destroys an event loop created by an |
376 | Like C<ev_default_destroy>, but destroys an event loop created by an |
177 | earlier call to C<ev_loop_new>. |
377 | earlier call to C<ev_loop_new>. |
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181 | This function reinitialises the kernel state for backends that have |
381 | This function reinitialises the kernel state for backends that have |
182 | one. Despite the name, you can call it anytime, but it makes most sense |
382 | one. Despite the name, you can call it anytime, but it makes most sense |
183 | after forking, in either the parent or child process (or both, but that |
383 | after forking, in either the parent or child process (or both, but that |
184 | again makes little sense). |
384 | again makes little sense). |
185 | |
385 | |
186 | You I<must> call this function after forking if and only if you want to |
386 | You I<must> call this function in the child process after forking if and |
187 | use the event library in both processes. If you just fork+exec, you don't |
387 | only if you want to use the event library in both processes. If you just |
188 | have to call it. |
388 | fork+exec, you don't have to call it. |
189 | |
389 | |
190 | The function itself is quite fast and it's usually not a problem to call |
390 | The function itself is quite fast and it's usually not a problem to call |
191 | 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 |
192 | quite nicely into a call to C<pthread_atfork>: |
392 | quite nicely into a call to C<pthread_atfork>: |
193 | |
393 | |
194 | pthread_atfork (0, 0, ev_default_fork); |
394 | pthread_atfork (0, 0, ev_default_fork); |
195 | |
395 | |
|
|
396 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
397 | without calling this function, so if you force one of those backends you |
|
|
398 | do not need to care. |
|
|
399 | |
196 | =item ev_loop_fork (loop) |
400 | =item ev_loop_fork (loop) |
197 | |
401 | |
198 | Like C<ev_default_fork>, but acts on an event loop created by |
402 | Like C<ev_default_fork>, but acts on an event loop created by |
199 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
403 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
200 | after fork, and how you do this is entirely your own problem. |
404 | after fork, and how you do this is entirely your own problem. |
201 | |
405 | |
202 | =item unsigned int ev_method (loop) |
406 | =item unsigned int ev_backend (loop) |
203 | |
407 | |
204 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
408 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
205 | use. |
409 | use. |
206 | |
410 | |
207 | =item ev_tstamp ev_now (loop) |
411 | =item ev_tstamp ev_now (loop) |
208 | |
412 | |
209 | Returns the current "event loop time", which is the time the event loop |
413 | Returns the current "event loop time", which is the time the event loop |
210 | got events and started processing them. This timestamp does not change |
414 | received events and started processing them. This timestamp does not |
211 | 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 |
212 | 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 |
213 | occuring (or more correctly, the mainloop finding out about it). |
417 | event occuring (or more correctly, libev finding out about it). |
214 | |
418 | |
215 | =item ev_loop (loop, int flags) |
419 | =item ev_loop (loop, int flags) |
216 | |
420 | |
217 | Finally, this is it, the event handler. This function usually is called |
421 | Finally, this is it, the event handler. This function usually is called |
218 | 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 |
219 | events. |
423 | events. |
220 | |
424 | |
221 | If the flags argument is specified as 0, it will not return until either |
425 | If the flags argument is specified as C<0>, it will not return until |
222 | no event watchers are active anymore or C<ev_unloop> was called. |
426 | either no event watchers are active anymore or C<ev_unloop> was called. |
|
|
427 | |
|
|
428 | Please note that an explicit C<ev_unloop> is usually better than |
|
|
429 | relying on all watchers to be stopped when deciding when a program has |
|
|
430 | finished (especially in interactive programs), but having a program that |
|
|
431 | automatically loops as long as it has to and no longer by virtue of |
|
|
432 | relying on its watchers stopping correctly is a thing of beauty. |
223 | |
433 | |
224 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
434 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
225 | those events and any outstanding ones, but will not block your process in |
435 | those events and any outstanding ones, but will not block your process in |
226 | case there are no events and will return after one iteration of the loop. |
436 | case there are no events and will return after one iteration of the loop. |
227 | |
437 | |
228 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
438 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
229 | neccessary) and will handle those and any outstanding ones. It will block |
439 | neccessary) and will handle those and any outstanding ones. It will block |
230 | your process until at least one new event arrives, and will return after |
440 | your process until at least one new event arrives, and will return after |
231 | one iteration of the loop. |
441 | one iteration of the loop. This is useful if you are waiting for some |
|
|
442 | external event in conjunction with something not expressible using other |
|
|
443 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
|
|
444 | usually a better approach for this kind of thing. |
232 | |
445 | |
233 | This flags value could be used to implement alternative looping |
446 | Here are the gory details of what C<ev_loop> does: |
234 | constructs, but the C<prepare> and C<check> watchers provide a better and |
447 | |
235 | more generic mechanism. |
448 | * If there are no active watchers (reference count is zero), return. |
|
|
449 | - Queue prepare watchers and then call all outstanding watchers. |
|
|
450 | - If we have been forked, recreate the kernel state. |
|
|
451 | - Update the kernel state with all outstanding changes. |
|
|
452 | - Update the "event loop time". |
|
|
453 | - Calculate for how long to block. |
|
|
454 | - Block the process, waiting for any events. |
|
|
455 | - Queue all outstanding I/O (fd) events. |
|
|
456 | - Update the "event loop time" and do time jump handling. |
|
|
457 | - Queue all outstanding timers. |
|
|
458 | - Queue all outstanding periodics. |
|
|
459 | - If no events are pending now, queue all idle watchers. |
|
|
460 | - Queue all check watchers. |
|
|
461 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
462 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
463 | be handled here by queueing them when their watcher gets executed. |
|
|
464 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
|
465 | were used, return, otherwise continue with step *. |
|
|
466 | |
|
|
467 | Example: queue some jobs and then loop until no events are outsanding |
|
|
468 | anymore. |
|
|
469 | |
|
|
470 | ... queue jobs here, make sure they register event watchers as long |
|
|
471 | ... as they still have work to do (even an idle watcher will do..) |
|
|
472 | ev_loop (my_loop, 0); |
|
|
473 | ... jobs done. yeah! |
236 | |
474 | |
237 | =item ev_unloop (loop, how) |
475 | =item ev_unloop (loop, how) |
238 | |
476 | |
239 | Can be used to make a call to C<ev_loop> return early (but only after it |
477 | Can be used to make a call to C<ev_loop> return early (but only after it |
240 | has processed all outstanding events). The C<how> argument must be either |
478 | has processed all outstanding events). The C<how> argument must be either |
241 | C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or |
479 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
242 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
480 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
243 | |
481 | |
244 | =item ev_ref (loop) |
482 | =item ev_ref (loop) |
245 | |
483 | |
246 | =item ev_unref (loop) |
484 | =item ev_unref (loop) |
… | |
… | |
254 | visible to the libev user and should not keep C<ev_loop> from exiting if |
492 | visible to the libev user and should not keep C<ev_loop> from exiting if |
255 | no event watchers registered by it are active. It is also an excellent |
493 | no event watchers registered by it are active. It is also an excellent |
256 | way to do this for generic recurring timers or from within third-party |
494 | way to do this for generic recurring timers or from within third-party |
257 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
495 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
258 | |
496 | |
|
|
497 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
|
|
498 | running when nothing else is active. |
|
|
499 | |
|
|
500 | struct dv_signal exitsig; |
|
|
501 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
502 | ev_signal_start (myloop, &exitsig); |
|
|
503 | evf_unref (myloop); |
|
|
504 | |
|
|
505 | Example: for some weird reason, unregister the above signal handler again. |
|
|
506 | |
|
|
507 | ev_ref (myloop); |
|
|
508 | ev_signal_stop (myloop, &exitsig); |
|
|
509 | |
259 | =back |
510 | =back |
|
|
511 | |
260 | |
512 | |
261 | =head1 ANATOMY OF A WATCHER |
513 | =head1 ANATOMY OF A WATCHER |
262 | |
514 | |
263 | A watcher is a structure that you create and register to record your |
515 | A watcher is a structure that you create and register to record your |
264 | interest in some event. For instance, if you want to wait for STDIN to |
516 | interest in some event. For instance, if you want to wait for STDIN to |
… | |
… | |
297 | *) >>), and you can stop watching for events at any time by calling the |
549 | *) >>), and you can stop watching for events at any time by calling the |
298 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
550 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
299 | |
551 | |
300 | As long as your watcher is active (has been started but not stopped) you |
552 | As long as your watcher is active (has been started but not stopped) you |
301 | must not touch the values stored in it. Most specifically you must never |
553 | must not touch the values stored in it. Most specifically you must never |
302 | reinitialise it or call its set method. |
554 | reinitialise it or call its C<set> macro. |
303 | |
|
|
304 | You cna check whether an event is active by calling the C<ev_is_active |
|
|
305 | (watcher *)> macro. To see whether an event is outstanding (but the |
|
|
306 | callback for it has not been called yet) you cna use the C<ev_is_pending |
|
|
307 | (watcher *)> macro. |
|
|
308 | |
555 | |
309 | Each and every callback receives the event loop pointer as first, the |
556 | Each and every callback receives the event loop pointer as first, the |
310 | registered watcher structure as second, and a bitset of received events as |
557 | registered watcher structure as second, and a bitset of received events as |
311 | third argument. |
558 | third argument. |
312 | |
559 | |
313 | The rceeived events usually include a single bit per event type received |
560 | The received events usually include a single bit per event type received |
314 | (you can receive multiple events at the same time). The possible bit masks |
561 | (you can receive multiple events at the same time). The possible bit masks |
315 | are: |
562 | are: |
316 | |
563 | |
317 | =over 4 |
564 | =over 4 |
318 | |
565 | |
… | |
… | |
336 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
583 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
337 | |
584 | |
338 | =item C<EV_CHILD> |
585 | =item C<EV_CHILD> |
339 | |
586 | |
340 | The pid specified in the C<ev_child> watcher has received a status change. |
587 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
588 | |
|
|
589 | =item C<EV_STAT> |
|
|
590 | |
|
|
591 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
341 | |
592 | |
342 | =item C<EV_IDLE> |
593 | =item C<EV_IDLE> |
343 | |
594 | |
344 | The C<ev_idle> watcher has determined that you have nothing better to do. |
595 | The C<ev_idle> watcher has determined that you have nothing better to do. |
345 | |
596 | |
… | |
… | |
353 | received events. Callbacks of both watcher types can start and stop as |
604 | received events. Callbacks of both watcher types can start and stop as |
354 | many watchers as they want, and all of them will be taken into account |
605 | many watchers as they want, and all of them will be taken into account |
355 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
606 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
356 | C<ev_loop> from blocking). |
607 | C<ev_loop> from blocking). |
357 | |
608 | |
|
|
609 | =item C<EV_EMBED> |
|
|
610 | |
|
|
611 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
|
|
612 | |
|
|
613 | =item C<EV_FORK> |
|
|
614 | |
|
|
615 | The event loop has been resumed in the child process after fork (see |
|
|
616 | C<ev_fork>). |
|
|
617 | |
358 | =item C<EV_ERROR> |
618 | =item C<EV_ERROR> |
359 | |
619 | |
360 | An unspecified error has occured, the watcher has been stopped. This might |
620 | An unspecified error has occured, the watcher has been stopped. This might |
361 | happen because the watcher could not be properly started because libev |
621 | happen because the watcher could not be properly started because libev |
362 | ran out of memory, a file descriptor was found to be closed or any other |
622 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
369 | with the error from read() or write(). This will not work in multithreaded |
629 | with the error from read() or write(). This will not work in multithreaded |
370 | programs, though, so beware. |
630 | programs, though, so beware. |
371 | |
631 | |
372 | =back |
632 | =back |
373 | |
633 | |
|
|
634 | =head2 GENERIC WATCHER FUNCTIONS |
|
|
635 | |
|
|
636 | In the following description, C<TYPE> stands for the watcher type, |
|
|
637 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
|
|
638 | |
|
|
639 | =over 4 |
|
|
640 | |
|
|
641 | =item C<ev_init> (ev_TYPE *watcher, callback) |
|
|
642 | |
|
|
643 | This macro initialises the generic portion of a watcher. The contents |
|
|
644 | of the watcher object can be arbitrary (so C<malloc> will do). Only |
|
|
645 | the generic parts of the watcher are initialised, you I<need> to call |
|
|
646 | the type-specific C<ev_TYPE_set> macro afterwards to initialise the |
|
|
647 | type-specific parts. For each type there is also a C<ev_TYPE_init> macro |
|
|
648 | which rolls both calls into one. |
|
|
649 | |
|
|
650 | You can reinitialise a watcher at any time as long as it has been stopped |
|
|
651 | (or never started) and there are no pending events outstanding. |
|
|
652 | |
|
|
653 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
654 | int revents)>. |
|
|
655 | |
|
|
656 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
|
|
657 | |
|
|
658 | This macro initialises the type-specific parts of a watcher. You need to |
|
|
659 | call C<ev_init> at least once before you call this macro, but you can |
|
|
660 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
|
|
661 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
662 | difference to the C<ev_init> macro). |
|
|
663 | |
|
|
664 | Although some watcher types do not have type-specific arguments |
|
|
665 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
|
|
666 | |
|
|
667 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
|
|
668 | |
|
|
669 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
|
|
670 | calls into a single call. This is the most convinient method to initialise |
|
|
671 | a watcher. The same limitations apply, of course. |
|
|
672 | |
|
|
673 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
|
|
674 | |
|
|
675 | Starts (activates) the given watcher. Only active watchers will receive |
|
|
676 | events. If the watcher is already active nothing will happen. |
|
|
677 | |
|
|
678 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
|
|
679 | |
|
|
680 | Stops the given watcher again (if active) and clears the pending |
|
|
681 | status. It is possible that stopped watchers are pending (for example, |
|
|
682 | non-repeating timers are being stopped when they become pending), but |
|
|
683 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
|
|
684 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
685 | good idea to always call its C<ev_TYPE_stop> function. |
|
|
686 | |
|
|
687 | =item bool ev_is_active (ev_TYPE *watcher) |
|
|
688 | |
|
|
689 | Returns a true value iff the watcher is active (i.e. it has been started |
|
|
690 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
691 | it. |
|
|
692 | |
|
|
693 | =item bool ev_is_pending (ev_TYPE *watcher) |
|
|
694 | |
|
|
695 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
696 | events but its callback has not yet been invoked). As long as a watcher |
|
|
697 | is pending (but not active) you must not call an init function on it (but |
|
|
698 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
|
|
699 | libev (e.g. you cnanot C<free ()> it). |
|
|
700 | |
|
|
701 | =item callback = ev_cb (ev_TYPE *watcher) |
|
|
702 | |
|
|
703 | Returns the callback currently set on the watcher. |
|
|
704 | |
|
|
705 | =item ev_cb_set (ev_TYPE *watcher, callback) |
|
|
706 | |
|
|
707 | Change the callback. You can change the callback at virtually any time |
|
|
708 | (modulo threads). |
|
|
709 | |
|
|
710 | =back |
|
|
711 | |
|
|
712 | |
374 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
713 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
375 | |
714 | |
376 | Each watcher has, by default, a member C<void *data> that you can change |
715 | Each watcher has, by default, a member C<void *data> that you can change |
377 | and read at any time, libev will completely ignore it. This cna be used |
716 | and read at any time, libev will completely ignore it. This can be used |
378 | to associate arbitrary data with your watcher. If you need more data and |
717 | to associate arbitrary data with your watcher. If you need more data and |
379 | don't want to allocate memory and store a pointer to it in that data |
718 | don't want to allocate memory and store a pointer to it in that data |
380 | member, you can also "subclass" the watcher type and provide your own |
719 | member, you can also "subclass" the watcher type and provide your own |
381 | data: |
720 | data: |
382 | |
721 | |
… | |
… | |
402 | |
741 | |
403 | |
742 | |
404 | =head1 WATCHER TYPES |
743 | =head1 WATCHER TYPES |
405 | |
744 | |
406 | This section describes each watcher in detail, but will not repeat |
745 | This section describes each watcher in detail, but will not repeat |
407 | information given in the last section. |
746 | information given in the last section. Any initialisation/set macros, |
|
|
747 | functions and members specific to the watcher type are explained. |
408 | |
748 | |
|
|
749 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
750 | while the watcher is active, you can look at the member and expect some |
|
|
751 | sensible content, but you must not modify it (you can modify it while the |
|
|
752 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
753 | means you can expect it to have some sensible content while the watcher |
|
|
754 | is active, but you can also modify it. Modifying it may not do something |
|
|
755 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
756 | not crash or malfunction in any way. |
|
|
757 | |
|
|
758 | |
409 | =head2 C<ev_io> - is this file descriptor readable or writable |
759 | =head2 C<ev_io> - is this file descriptor readable or writable? |
410 | |
760 | |
411 | I/O watchers check whether a file descriptor is readable or writable |
761 | I/O watchers check whether a file descriptor is readable or writable |
412 | in each iteration of the event loop (This behaviour is called |
762 | in each iteration of the event loop, or, more precisely, when reading |
413 | level-triggering because you keep receiving events as long as the |
763 | would not block the process and writing would at least be able to write |
414 | condition persists. Remember you cna stop the watcher if you don't want to |
764 | some data. This behaviour is called level-triggering because you keep |
415 | act on the event and neither want to receive future events). |
765 | receiving events as long as the condition persists. Remember you can stop |
|
|
766 | the watcher if you don't want to act on the event and neither want to |
|
|
767 | receive future events. |
416 | |
768 | |
417 | In general you can register as many read and/or write event watchers oer |
769 | In general you can register as many read and/or write event watchers per |
418 | fd as you want (as long as you don't confuse yourself). Setting all file |
770 | fd as you want (as long as you don't confuse yourself). Setting all file |
419 | descriptors to non-blocking mode is also usually a good idea (but not |
771 | descriptors to non-blocking mode is also usually a good idea (but not |
420 | required if you know what you are doing). |
772 | required if you know what you are doing). |
421 | |
773 | |
422 | You have to be careful with dup'ed file descriptors, though. Some backends |
774 | You have to be careful with dup'ed file descriptors, though. Some backends |
423 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
775 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
424 | descriptors correctly if you register interest in two or more fds pointing |
776 | descriptors correctly if you register interest in two or more fds pointing |
425 | to the same file/socket etc. description. |
777 | to the same underlying file/socket/etc. description (that is, they share |
|
|
778 | the same underlying "file open"). |
426 | |
779 | |
427 | If you must do this, then force the use of a known-to-be-good backend |
780 | If you must do this, then force the use of a known-to-be-good backend |
428 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
781 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
429 | EVMETHOD_POLL). |
782 | C<EVBACKEND_POLL>). |
|
|
783 | |
|
|
784 | Another thing you have to watch out for is that it is quite easy to |
|
|
785 | receive "spurious" readyness notifications, that is your callback might |
|
|
786 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
787 | because there is no data. Not only are some backends known to create a |
|
|
788 | lot of those (for example solaris ports), it is very easy to get into |
|
|
789 | this situation even with a relatively standard program structure. Thus |
|
|
790 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
791 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
792 | |
|
|
793 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
794 | play around with an Xlib connection), then you have to seperately re-test |
|
|
795 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
796 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
797 | its own, so its quite safe to use). |
430 | |
798 | |
431 | =over 4 |
799 | =over 4 |
432 | |
800 | |
433 | =item ev_io_init (ev_io *, callback, int fd, int events) |
801 | =item ev_io_init (ev_io *, callback, int fd, int events) |
434 | |
802 | |
435 | =item ev_io_set (ev_io *, int fd, int events) |
803 | =item ev_io_set (ev_io *, int fd, int events) |
436 | |
804 | |
437 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
805 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
438 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
806 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
439 | EV_WRITE> to receive the given events. |
807 | C<EV_READ | EV_WRITE> to receive the given events. |
|
|
808 | |
|
|
809 | =item int fd [read-only] |
|
|
810 | |
|
|
811 | The file descriptor being watched. |
|
|
812 | |
|
|
813 | =item int events [read-only] |
|
|
814 | |
|
|
815 | The events being watched. |
440 | |
816 | |
441 | =back |
817 | =back |
442 | |
818 | |
|
|
819 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
|
|
820 | readable, but only once. Since it is likely line-buffered, you could |
|
|
821 | attempt to read a whole line in the callback: |
|
|
822 | |
|
|
823 | static void |
|
|
824 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
825 | { |
|
|
826 | ev_io_stop (loop, w); |
|
|
827 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
828 | } |
|
|
829 | |
|
|
830 | ... |
|
|
831 | struct ev_loop *loop = ev_default_init (0); |
|
|
832 | struct ev_io stdin_readable; |
|
|
833 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
834 | ev_io_start (loop, &stdin_readable); |
|
|
835 | ev_loop (loop, 0); |
|
|
836 | |
|
|
837 | |
443 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
838 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
444 | |
839 | |
445 | Timer watchers are simple relative timers that generate an event after a |
840 | Timer watchers are simple relative timers that generate an event after a |
446 | given time, and optionally repeating in regular intervals after that. |
841 | given time, and optionally repeating in regular intervals after that. |
447 | |
842 | |
448 | The timers are based on real time, that is, if you register an event that |
843 | The timers are based on real time, that is, if you register an event that |
449 | times out after an hour and youreset your system clock to last years |
844 | times out after an hour and you reset your system clock to last years |
450 | time, it will still time out after (roughly) and hour. "Roughly" because |
845 | time, it will still time out after (roughly) and hour. "Roughly" because |
451 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
846 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
452 | monotonic clock option helps a lot here). |
847 | monotonic clock option helps a lot here). |
453 | |
848 | |
454 | The relative timeouts are calculated relative to the C<ev_now ()> |
849 | The relative timeouts are calculated relative to the C<ev_now ()> |
455 | time. This is usually the right thing as this timestamp refers to the time |
850 | time. This is usually the right thing as this timestamp refers to the time |
456 | of the event triggering whatever timeout you are modifying/starting. If |
851 | of the event triggering whatever timeout you are modifying/starting. If |
457 | you suspect event processing to be delayed and you *need* to base the timeout |
852 | you suspect event processing to be delayed and you I<need> to base the timeout |
458 | ion the current time, use something like this to adjust for this: |
853 | on the current time, use something like this to adjust for this: |
459 | |
854 | |
460 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
855 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
856 | |
|
|
857 | The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
858 | but if multiple timers become ready during the same loop iteration then |
|
|
859 | order of execution is undefined. |
461 | |
860 | |
462 | =over 4 |
861 | =over 4 |
463 | |
862 | |
464 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
863 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
465 | |
864 | |
… | |
… | |
471 | later, again, and again, until stopped manually. |
870 | later, again, and again, until stopped manually. |
472 | |
871 | |
473 | The timer itself will do a best-effort at avoiding drift, that is, if you |
872 | The timer itself will do a best-effort at avoiding drift, that is, if you |
474 | configure a timer to trigger every 10 seconds, then it will trigger at |
873 | configure a timer to trigger every 10 seconds, then it will trigger at |
475 | exactly 10 second intervals. If, however, your program cannot keep up with |
874 | exactly 10 second intervals. If, however, your program cannot keep up with |
476 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
875 | the timer (because it takes longer than those 10 seconds to do stuff) the |
477 | timer will not fire more than once per event loop iteration. |
876 | timer will not fire more than once per event loop iteration. |
478 | |
877 | |
479 | =item ev_timer_again (loop) |
878 | =item ev_timer_again (loop) |
480 | |
879 | |
481 | This will act as if the timer timed out and restart it again if it is |
880 | This will act as if the timer timed out and restart it again if it is |
… | |
… | |
485 | |
884 | |
486 | If the timer is repeating, either start it if necessary (with the repeat |
885 | If the timer is repeating, either start it if necessary (with the repeat |
487 | value), or reset the running timer to the repeat value. |
886 | value), or reset the running timer to the repeat value. |
488 | |
887 | |
489 | This sounds a bit complicated, but here is a useful and typical |
888 | This sounds a bit complicated, but here is a useful and typical |
490 | example: Imagine you have a tcp connection and you want a so-called idle |
889 | example: Imagine you have a tcp connection and you want a so-called |
491 | timeout, that is, you want to be called when there have been, say, 60 |
890 | idle timeout, that is, you want to be called when there have been, |
492 | seconds of inactivity on the socket. The easiest way to do this is to |
891 | say, 60 seconds of inactivity on the socket. The easiest way to do |
493 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
892 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
494 | time you successfully read or write some data. If you go into an idle |
893 | C<ev_timer_again> each time you successfully read or write some data. If |
495 | state where you do not expect data to travel on the socket, you can stop |
894 | you go into an idle state where you do not expect data to travel on the |
496 | the timer, and again will automatically restart it if need be. |
895 | socket, you can stop the timer, and again will automatically restart it if |
|
|
896 | need be. |
|
|
897 | |
|
|
898 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
|
|
899 | and only ever use the C<repeat> value: |
|
|
900 | |
|
|
901 | ev_timer_init (timer, callback, 0., 5.); |
|
|
902 | ev_timer_again (loop, timer); |
|
|
903 | ... |
|
|
904 | timer->again = 17.; |
|
|
905 | ev_timer_again (loop, timer); |
|
|
906 | ... |
|
|
907 | timer->again = 10.; |
|
|
908 | ev_timer_again (loop, timer); |
|
|
909 | |
|
|
910 | This is more efficient then stopping/starting the timer eahc time you want |
|
|
911 | to modify its timeout value. |
|
|
912 | |
|
|
913 | =item ev_tstamp repeat [read-write] |
|
|
914 | |
|
|
915 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
916 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
917 | which is also when any modifications are taken into account. |
497 | |
918 | |
498 | =back |
919 | =back |
499 | |
920 | |
|
|
921 | Example: create a timer that fires after 60 seconds. |
|
|
922 | |
|
|
923 | static void |
|
|
924 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
925 | { |
|
|
926 | .. one minute over, w is actually stopped right here |
|
|
927 | } |
|
|
928 | |
|
|
929 | struct ev_timer mytimer; |
|
|
930 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
931 | ev_timer_start (loop, &mytimer); |
|
|
932 | |
|
|
933 | Example: create a timeout timer that times out after 10 seconds of |
|
|
934 | inactivity. |
|
|
935 | |
|
|
936 | static void |
|
|
937 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
938 | { |
|
|
939 | .. ten seconds without any activity |
|
|
940 | } |
|
|
941 | |
|
|
942 | struct ev_timer mytimer; |
|
|
943 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
944 | ev_timer_again (&mytimer); /* start timer */ |
|
|
945 | ev_loop (loop, 0); |
|
|
946 | |
|
|
947 | // and in some piece of code that gets executed on any "activity": |
|
|
948 | // reset the timeout to start ticking again at 10 seconds |
|
|
949 | ev_timer_again (&mytimer); |
|
|
950 | |
|
|
951 | |
500 | =head2 C<ev_periodic> - to cron or not to cron it |
952 | =head2 C<ev_periodic> - to cron or not to cron? |
501 | |
953 | |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
954 | Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex). |
955 | (and unfortunately a bit complex). |
504 | |
956 | |
505 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
957 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
506 | but on wallclock time (absolute time). You can tell a periodic watcher |
958 | but on wallclock time (absolute time). You can tell a periodic watcher |
507 | to trigger "at" some specific point in time. For example, if you tell a |
959 | to trigger "at" some specific point in time. For example, if you tell a |
508 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
960 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
509 | + 10.>) and then reset your system clock to the last year, then it will |
961 | + 10.>) and then reset your system clock to the last year, then it will |
510 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
962 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
511 | roughly 10 seconds later and of course not if you reset your system time |
963 | roughly 10 seconds later and of course not if you reset your system time |
512 | again). |
964 | again). |
513 | |
965 | |
514 | They can also be used to implement vastly more complex timers, such as |
966 | They can also be used to implement vastly more complex timers, such as |
515 | triggering an event on eahc midnight, local time. |
967 | triggering an event on eahc midnight, local time. |
516 | |
968 | |
|
|
969 | As with timers, the callback is guarenteed to be invoked only when the |
|
|
970 | time (C<at>) has been passed, but if multiple periodic timers become ready |
|
|
971 | during the same loop iteration then order of execution is undefined. |
|
|
972 | |
517 | =over 4 |
973 | =over 4 |
518 | |
974 | |
519 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
975 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
520 | |
976 | |
521 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
977 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
522 | |
978 | |
523 | Lots of arguments, lets sort it out... There are basically three modes of |
979 | Lots of arguments, lets sort it out... There are basically three modes of |
524 | operation, and we will explain them from simplest to complex: |
980 | operation, and we will explain them from simplest to complex: |
525 | |
|
|
526 | |
981 | |
527 | =over 4 |
982 | =over 4 |
528 | |
983 | |
529 | =item * absolute timer (interval = reschedule_cb = 0) |
984 | =item * absolute timer (interval = reschedule_cb = 0) |
530 | |
985 | |
… | |
… | |
558 | In this mode the values for C<interval> and C<at> are both being |
1013 | In this mode the values for C<interval> and C<at> are both being |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1014 | ignored. Instead, each time the periodic watcher gets scheduled, the |
560 | reschedule callback will be called with the watcher as first, and the |
1015 | reschedule callback will be called with the watcher as first, and the |
561 | current time as second argument. |
1016 | current time as second argument. |
562 | |
1017 | |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
1018 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
564 | periodic watcher, ever, or make any event loop modifications>. If you need |
1019 | ever, or make any event loop modifications>. If you need to stop it, |
565 | to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards. |
1020 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
566 | |
1021 | starting a prepare watcher). |
567 | Also, I<< this callback must always return a time that is later than the |
|
|
568 | passed C<now> value >>. Not even C<now> itself will be ok. |
|
|
569 | |
1022 | |
570 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1023 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
571 | ev_tstamp now)>, e.g.: |
1024 | ev_tstamp now)>, e.g.: |
572 | |
1025 | |
573 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1026 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
578 | It must return the next time to trigger, based on the passed time value |
1031 | It must return the next time to trigger, based on the passed time value |
579 | (that is, the lowest time value larger than to the second argument). It |
1032 | (that is, the lowest time value larger than to the second argument). It |
580 | will usually be called just before the callback will be triggered, but |
1033 | will usually be called just before the callback will be triggered, but |
581 | might be called at other times, too. |
1034 | might be called at other times, too. |
582 | |
1035 | |
|
|
1036 | NOTE: I<< This callback must always return a time that is later than the |
|
|
1037 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
|
|
1038 | |
583 | This can be used to create very complex timers, such as a timer that |
1039 | This can be used to create very complex timers, such as a timer that |
584 | triggers on each midnight, local time. To do this, you would calculate the |
1040 | triggers on each midnight, local time. To do this, you would calculate the |
585 | next midnight after C<now> and return the timestamp value for this. How you do this |
1041 | next midnight after C<now> and return the timestamp value for this. How |
586 | is, again, up to you (but it is not trivial). |
1042 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
1043 | reason I omitted it as an example). |
587 | |
1044 | |
588 | =back |
1045 | =back |
589 | |
1046 | |
590 | =item ev_periodic_again (loop, ev_periodic *) |
1047 | =item ev_periodic_again (loop, ev_periodic *) |
591 | |
1048 | |
592 | Simply stops and restarts the periodic watcher again. This is only useful |
1049 | Simply stops and restarts the periodic watcher again. This is only useful |
593 | when you changed some parameters or the reschedule callback would return |
1050 | when you changed some parameters or the reschedule callback would return |
594 | a different time than the last time it was called (e.g. in a crond like |
1051 | a different time than the last time it was called (e.g. in a crond like |
595 | program when the crontabs have changed). |
1052 | program when the crontabs have changed). |
596 | |
1053 | |
|
|
1054 | =item ev_tstamp interval [read-write] |
|
|
1055 | |
|
|
1056 | The current interval value. Can be modified any time, but changes only |
|
|
1057 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1058 | called. |
|
|
1059 | |
|
|
1060 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1061 | |
|
|
1062 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1063 | switched off. Can be changed any time, but changes only take effect when |
|
|
1064 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1065 | |
597 | =back |
1066 | =back |
598 | |
1067 | |
|
|
1068 | Example: call a callback every hour, or, more precisely, whenever the |
|
|
1069 | system clock is divisible by 3600. The callback invocation times have |
|
|
1070 | potentially a lot of jittering, but good long-term stability. |
|
|
1071 | |
|
|
1072 | static void |
|
|
1073 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1074 | { |
|
|
1075 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
1076 | } |
|
|
1077 | |
|
|
1078 | struct ev_periodic hourly_tick; |
|
|
1079 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
1080 | ev_periodic_start (loop, &hourly_tick); |
|
|
1081 | |
|
|
1082 | Example: the same as above, but use a reschedule callback to do it: |
|
|
1083 | |
|
|
1084 | #include <math.h> |
|
|
1085 | |
|
|
1086 | static ev_tstamp |
|
|
1087 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1088 | { |
|
|
1089 | return fmod (now, 3600.) + 3600.; |
|
|
1090 | } |
|
|
1091 | |
|
|
1092 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1093 | |
|
|
1094 | Example: call a callback every hour, starting now: |
|
|
1095 | |
|
|
1096 | struct ev_periodic hourly_tick; |
|
|
1097 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1098 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1099 | ev_periodic_start (loop, &hourly_tick); |
|
|
1100 | |
|
|
1101 | |
599 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1102 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
600 | |
1103 | |
601 | Signal watchers will trigger an event when the process receives a specific |
1104 | Signal watchers will trigger an event when the process receives a specific |
602 | signal one or more times. Even though signals are very asynchronous, libev |
1105 | signal one or more times. Even though signals are very asynchronous, libev |
603 | will try it's best to deliver signals synchronously, i.e. as part of the |
1106 | will try it's best to deliver signals synchronously, i.e. as part of the |
604 | normal event processing, like any other event. |
1107 | normal event processing, like any other event. |
605 | |
1108 | |
606 | You cna configure as many watchers as you like per signal. Only when the |
1109 | You can configure as many watchers as you like per signal. Only when the |
607 | first watcher gets started will libev actually register a signal watcher |
1110 | first watcher gets started will libev actually register a signal watcher |
608 | with the kernel (thus it coexists with your own signal handlers as long |
1111 | with the kernel (thus it coexists with your own signal handlers as long |
609 | as you don't register any with libev). Similarly, when the last signal |
1112 | as you don't register any with libev). Similarly, when the last signal |
610 | watcher for a signal is stopped libev will reset the signal handler to |
1113 | watcher for a signal is stopped libev will reset the signal handler to |
611 | SIG_DFL (regardless of what it was set to before). |
1114 | SIG_DFL (regardless of what it was set to before). |
… | |
… | |
617 | =item ev_signal_set (ev_signal *, int signum) |
1120 | =item ev_signal_set (ev_signal *, int signum) |
618 | |
1121 | |
619 | Configures the watcher to trigger on the given signal number (usually one |
1122 | Configures the watcher to trigger on the given signal number (usually one |
620 | of the C<SIGxxx> constants). |
1123 | of the C<SIGxxx> constants). |
621 | |
1124 | |
|
|
1125 | =item int signum [read-only] |
|
|
1126 | |
|
|
1127 | The signal the watcher watches out for. |
|
|
1128 | |
622 | =back |
1129 | =back |
623 | |
1130 | |
|
|
1131 | |
624 | =head2 C<ev_child> - wait for pid status changes |
1132 | =head2 C<ev_child> - watch out for process status changes |
625 | |
1133 | |
626 | Child watchers trigger when your process receives a SIGCHLD in response to |
1134 | Child watchers trigger when your process receives a SIGCHLD in response to |
627 | some child status changes (most typically when a child of yours dies). |
1135 | some child status changes (most typically when a child of yours dies). |
628 | |
1136 | |
629 | =over 4 |
1137 | =over 4 |
… | |
… | |
633 | =item ev_child_set (ev_child *, int pid) |
1141 | =item ev_child_set (ev_child *, int pid) |
634 | |
1142 | |
635 | Configures the watcher to wait for status changes of process C<pid> (or |
1143 | Configures the watcher to wait for status changes of process C<pid> (or |
636 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1144 | I<any> process if C<pid> is specified as C<0>). The callback can look |
637 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1145 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
638 | the status word (use the macros from C<sys/wait.h>). The C<rpid> member |
1146 | the status word (use the macros from C<sys/wait.h> and see your systems |
639 | contains the pid of the process causing the status change. |
1147 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
|
|
1148 | process causing the status change. |
|
|
1149 | |
|
|
1150 | =item int pid [read-only] |
|
|
1151 | |
|
|
1152 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1153 | |
|
|
1154 | =item int rpid [read-write] |
|
|
1155 | |
|
|
1156 | The process id that detected a status change. |
|
|
1157 | |
|
|
1158 | =item int rstatus [read-write] |
|
|
1159 | |
|
|
1160 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1161 | C<waitpid> and C<sys/wait.h> documentation for details). |
640 | |
1162 | |
641 | =back |
1163 | =back |
642 | |
1164 | |
|
|
1165 | Example: try to exit cleanly on SIGINT and SIGTERM. |
|
|
1166 | |
|
|
1167 | static void |
|
|
1168 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1169 | { |
|
|
1170 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1171 | } |
|
|
1172 | |
|
|
1173 | struct ev_signal signal_watcher; |
|
|
1174 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1175 | ev_signal_start (loop, &sigint_cb); |
|
|
1176 | |
|
|
1177 | |
|
|
1178 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1179 | |
|
|
1180 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1181 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1182 | compared to the last time, invoking the callback if it did. |
|
|
1183 | |
|
|
1184 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1185 | not exist" is a status change like any other. The condition "path does |
|
|
1186 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1187 | otherwise always forced to be at least one) and all the other fields of |
|
|
1188 | the stat buffer having unspecified contents. |
|
|
1189 | |
|
|
1190 | Since there is no standard to do this, the portable implementation simply |
|
|
1191 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
|
|
1192 | can specify a recommended polling interval for this case. If you specify |
|
|
1193 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1194 | unspecified default> value will be used (which you can expect to be around |
|
|
1195 | five seconds, although this might change dynamically). Libev will also |
|
|
1196 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1197 | usually overkill. |
|
|
1198 | |
|
|
1199 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1200 | as even with OS-supported change notifications, this can be |
|
|
1201 | resource-intensive. |
|
|
1202 | |
|
|
1203 | At the time of this writing, no specific OS backends are implemented, but |
|
|
1204 | if demand increases, at least a kqueue and inotify backend will be added. |
|
|
1205 | |
|
|
1206 | =over 4 |
|
|
1207 | |
|
|
1208 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1209 | |
|
|
1210 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1211 | |
|
|
1212 | Configures the watcher to wait for status changes of the given |
|
|
1213 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1214 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1215 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1216 | path for as long as the watcher is active. |
|
|
1217 | |
|
|
1218 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1219 | relative to the attributes at the time the watcher was started (or the |
|
|
1220 | last change was detected). |
|
|
1221 | |
|
|
1222 | =item ev_stat_stat (ev_stat *) |
|
|
1223 | |
|
|
1224 | Updates the stat buffer immediately with new values. If you change the |
|
|
1225 | watched path in your callback, you could call this fucntion to avoid |
|
|
1226 | detecting this change (while introducing a race condition). Can also be |
|
|
1227 | useful simply to find out the new values. |
|
|
1228 | |
|
|
1229 | =item ev_statdata attr [read-only] |
|
|
1230 | |
|
|
1231 | The most-recently detected attributes of the file. Although the type is of |
|
|
1232 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1233 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1234 | was some error while C<stat>ing the file. |
|
|
1235 | |
|
|
1236 | =item ev_statdata prev [read-only] |
|
|
1237 | |
|
|
1238 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1239 | C<prev> != C<attr>. |
|
|
1240 | |
|
|
1241 | =item ev_tstamp interval [read-only] |
|
|
1242 | |
|
|
1243 | The specified interval. |
|
|
1244 | |
|
|
1245 | =item const char *path [read-only] |
|
|
1246 | |
|
|
1247 | The filesystem path that is being watched. |
|
|
1248 | |
|
|
1249 | =back |
|
|
1250 | |
|
|
1251 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1252 | |
|
|
1253 | static void |
|
|
1254 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1255 | { |
|
|
1256 | /* /etc/passwd changed in some way */ |
|
|
1257 | if (w->attr.st_nlink) |
|
|
1258 | { |
|
|
1259 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1260 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1261 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1262 | } |
|
|
1263 | else |
|
|
1264 | /* you shalt not abuse printf for puts */ |
|
|
1265 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1266 | "if this is windows, they already arrived\n"); |
|
|
1267 | } |
|
|
1268 | |
|
|
1269 | ... |
|
|
1270 | ev_stat passwd; |
|
|
1271 | |
|
|
1272 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1273 | ev_stat_start (loop, &passwd); |
|
|
1274 | |
|
|
1275 | |
643 | =head2 C<ev_idle> - when you've got nothing better to do |
1276 | =head2 C<ev_idle> - when you've got nothing better to do... |
644 | |
1277 | |
645 | Idle watchers trigger events when there are no other I/O or timer (or |
1278 | Idle watchers trigger events when there are no other events are pending |
646 | periodic) events pending. That is, as long as your process is busy |
1279 | (prepare, check and other idle watchers do not count). That is, as long |
647 | handling sockets or timeouts it will not be called. But when your process |
1280 | as your process is busy handling sockets or timeouts (or even signals, |
648 | is idle all idle watchers are being called again and again - until |
1281 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
1282 | watchers are being called again and again, once per event loop iteration - |
649 | stopped, that is, or your process receives more events. |
1283 | until stopped, that is, or your process receives more events and becomes |
|
|
1284 | busy. |
650 | |
1285 | |
651 | The most noteworthy effect is that as long as any idle watchers are |
1286 | The most noteworthy effect is that as long as any idle watchers are |
652 | active, the process will not block when waiting for new events. |
1287 | active, the process will not block when waiting for new events. |
653 | |
1288 | |
654 | Apart from keeping your process non-blocking (which is a useful |
1289 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
664 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1299 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
665 | believe me. |
1300 | believe me. |
666 | |
1301 | |
667 | =back |
1302 | =back |
668 | |
1303 | |
669 | =head2 prepare and check - your hooks into the event loop |
1304 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
|
|
1305 | callback, free it. Alos, use no error checking, as usual. |
670 | |
1306 | |
|
|
1307 | static void |
|
|
1308 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1309 | { |
|
|
1310 | free (w); |
|
|
1311 | // now do something you wanted to do when the program has |
|
|
1312 | // no longer asnything immediate to do. |
|
|
1313 | } |
|
|
1314 | |
|
|
1315 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1316 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1317 | ev_idle_start (loop, idle_cb); |
|
|
1318 | |
|
|
1319 | |
|
|
1320 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
|
|
1321 | |
671 | Prepare and check watchers usually (but not always) are used in |
1322 | Prepare and check watchers are usually (but not always) used in tandem: |
672 | tandom. Prepare watchers get invoked before the process blocks and check |
1323 | prepare watchers get invoked before the process blocks and check watchers |
673 | watchers afterwards. |
1324 | afterwards. |
674 | |
1325 | |
|
|
1326 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1327 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1328 | watchers. Other loops than the current one are fine, however. The |
|
|
1329 | rationale behind this is that you do not need to check for recursion in |
|
|
1330 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1331 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1332 | called in pairs bracketing the blocking call. |
|
|
1333 | |
675 | Their main purpose is to integrate other event mechanisms into libev. This |
1334 | Their main purpose is to integrate other event mechanisms into libev and |
676 | could be used, for example, to track variable changes, implement your own |
1335 | their use is somewhat advanced. This could be used, for example, to track |
677 | watchers, integrate net-snmp or a coroutine library and lots more. |
1336 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1337 | coroutine library and lots more. They are also occasionally useful if |
|
|
1338 | you cache some data and want to flush it before blocking (for example, |
|
|
1339 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1340 | watcher). |
678 | |
1341 | |
679 | This is done by examining in each prepare call which file descriptors need |
1342 | This is done by examining in each prepare call which file descriptors need |
680 | to be watched by the other library, registering C<ev_io> watchers for them |
1343 | to be watched by the other library, registering C<ev_io> watchers for |
681 | and starting an C<ev_timer> watcher for any timeouts (many libraries provide |
1344 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
682 | just this functionality). Then, in the check watcher you check for any |
1345 | provide just this functionality). Then, in the check watcher you check for |
683 | events that occured (by making your callbacks set soem flags for example) |
1346 | any events that occured (by checking the pending status of all watchers |
684 | and call back into the library. |
1347 | and stopping them) and call back into the library. The I/O and timer |
|
|
1348 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
1349 | because you never know, you know?). |
685 | |
1350 | |
686 | As another example, the perl Coro module uses these hooks to integrate |
1351 | As another example, the Perl Coro module uses these hooks to integrate |
687 | coroutines into libev programs, by yielding to other active coroutines |
1352 | coroutines into libev programs, by yielding to other active coroutines |
688 | during each prepare and only letting the process block if no coroutines |
1353 | during each prepare and only letting the process block if no coroutines |
689 | are ready to run. |
1354 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
1355 | with priority higher than or equal to the event loop and one coroutine |
|
|
1356 | of lower priority, but only once, using idle watchers to keep the event |
|
|
1357 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
1358 | low-priority coroutines to idle/background tasks). |
690 | |
1359 | |
691 | =over 4 |
1360 | =over 4 |
692 | |
1361 | |
693 | =item ev_prepare_init (ev_prepare *, callback) |
1362 | =item ev_prepare_init (ev_prepare *, callback) |
694 | |
1363 | |
695 | =item ev_check_init (ev_check *, callback) |
1364 | =item ev_check_init (ev_check *, callback) |
696 | |
1365 | |
697 | Initialises and configures the prepare or check watcher - they have no |
1366 | Initialises and configures the prepare or check watcher - they have no |
698 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1367 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
699 | macros, but using them is utterly, utterly pointless. |
1368 | macros, but using them is utterly, utterly and completely pointless. |
700 | |
1369 | |
701 | =back |
1370 | =back |
702 | |
1371 | |
|
|
1372 | Example: To include a library such as adns, you would add IO watchers |
|
|
1373 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1374 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1375 | pseudo-code only of course: |
|
|
1376 | |
|
|
1377 | static ev_io iow [nfd]; |
|
|
1378 | static ev_timer tw; |
|
|
1379 | |
|
|
1380 | static void |
|
|
1381 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1382 | { |
|
|
1383 | // set the relevant poll flags |
|
|
1384 | // could also call adns_processreadable etc. here |
|
|
1385 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1386 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1387 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1388 | } |
|
|
1389 | |
|
|
1390 | // create io watchers for each fd and a timer before blocking |
|
|
1391 | static void |
|
|
1392 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1393 | { |
|
|
1394 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1395 | // actual code will need to loop here and realloc etc. |
|
|
1396 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1397 | |
|
|
1398 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1399 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1400 | ev_timer_start (loop, &tw); |
|
|
1401 | |
|
|
1402 | // create on ev_io per pollfd |
|
|
1403 | for (int i = 0; i < nfd; ++i) |
|
|
1404 | { |
|
|
1405 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1406 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1407 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1408 | |
|
|
1409 | fds [i].revents = 0; |
|
|
1410 | iow [i].data = fds + i; |
|
|
1411 | ev_io_start (loop, iow + i); |
|
|
1412 | } |
|
|
1413 | } |
|
|
1414 | |
|
|
1415 | // stop all watchers after blocking |
|
|
1416 | static void |
|
|
1417 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1418 | { |
|
|
1419 | ev_timer_stop (loop, &tw); |
|
|
1420 | |
|
|
1421 | for (int i = 0; i < nfd; ++i) |
|
|
1422 | ev_io_stop (loop, iow + i); |
|
|
1423 | |
|
|
1424 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1425 | } |
|
|
1426 | |
|
|
1427 | |
|
|
1428 | =head2 C<ev_embed> - when one backend isn't enough... |
|
|
1429 | |
|
|
1430 | This is a rather advanced watcher type that lets you embed one event loop |
|
|
1431 | into another (currently only C<ev_io> events are supported in the embedded |
|
|
1432 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1433 | fashion and must not be used). |
|
|
1434 | |
|
|
1435 | There are primarily two reasons you would want that: work around bugs and |
|
|
1436 | prioritise I/O. |
|
|
1437 | |
|
|
1438 | As an example for a bug workaround, the kqueue backend might only support |
|
|
1439 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1440 | still want to make use of it because you have many sockets and it scales |
|
|
1441 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1442 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1443 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1444 | at least you can use both at what they are best. |
|
|
1445 | |
|
|
1446 | As for prioritising I/O: rarely you have the case where some fds have |
|
|
1447 | to be watched and handled very quickly (with low latency), and even |
|
|
1448 | priorities and idle watchers might have too much overhead. In this case |
|
|
1449 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1450 | a second one, and embed the second one in the first. |
|
|
1451 | |
|
|
1452 | As long as the watcher is active, the callback will be invoked every time |
|
|
1453 | there might be events pending in the embedded loop. The callback must then |
|
|
1454 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
|
|
1455 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1456 | loop strictly lower priority for example). You can also set the callback |
|
|
1457 | to C<0>, in which case the embed watcher will automatically execute the |
|
|
1458 | embedded loop sweep. |
|
|
1459 | |
|
|
1460 | As long as the watcher is started it will automatically handle events. The |
|
|
1461 | callback will be invoked whenever some events have been handled. You can |
|
|
1462 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
1463 | interested in that. |
|
|
1464 | |
|
|
1465 | Also, there have not currently been made special provisions for forking: |
|
|
1466 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
|
|
1467 | but you will also have to stop and restart any C<ev_embed> watchers |
|
|
1468 | yourself. |
|
|
1469 | |
|
|
1470 | Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1471 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
|
|
1472 | portable one. |
|
|
1473 | |
|
|
1474 | So when you want to use this feature you will always have to be prepared |
|
|
1475 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1476 | this is to have a separate variables for your embeddable loop, try to |
|
|
1477 | create it, and if that fails, use the normal loop for everything: |
|
|
1478 | |
|
|
1479 | struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1480 | struct ev_loop *loop_lo = 0; |
|
|
1481 | struct ev_embed embed; |
|
|
1482 | |
|
|
1483 | // see if there is a chance of getting one that works |
|
|
1484 | // (remember that a flags value of 0 means autodetection) |
|
|
1485 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1486 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1487 | : 0; |
|
|
1488 | |
|
|
1489 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1490 | if (loop_lo) |
|
|
1491 | { |
|
|
1492 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1493 | ev_embed_start (loop_hi, &embed); |
|
|
1494 | } |
|
|
1495 | else |
|
|
1496 | loop_lo = loop_hi; |
|
|
1497 | |
|
|
1498 | =over 4 |
|
|
1499 | |
|
|
1500 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1501 | |
|
|
1502 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1503 | |
|
|
1504 | Configures the watcher to embed the given loop, which must be |
|
|
1505 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1506 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1507 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1508 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1509 | |
|
|
1510 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1511 | |
|
|
1512 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1513 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1514 | apropriate way for embedded loops. |
|
|
1515 | |
|
|
1516 | =item struct ev_loop *loop [read-only] |
|
|
1517 | |
|
|
1518 | The embedded event loop. |
|
|
1519 | |
|
|
1520 | =back |
|
|
1521 | |
|
|
1522 | |
|
|
1523 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
1524 | |
|
|
1525 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
1526 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1527 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
1528 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
1529 | and only in the child after the fork. If whoever good citizen calling |
|
|
1530 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
1531 | handlers will be invoked, too, of course. |
|
|
1532 | |
|
|
1533 | =over 4 |
|
|
1534 | |
|
|
1535 | =item ev_fork_init (ev_signal *, callback) |
|
|
1536 | |
|
|
1537 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
1538 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
1539 | believe me. |
|
|
1540 | |
|
|
1541 | =back |
|
|
1542 | |
|
|
1543 | |
703 | =head1 OTHER FUNCTIONS |
1544 | =head1 OTHER FUNCTIONS |
704 | |
1545 | |
705 | There are some other fucntions of possible interest. Described. Here. Now. |
1546 | There are some other functions of possible interest. Described. Here. Now. |
706 | |
1547 | |
707 | =over 4 |
1548 | =over 4 |
708 | |
1549 | |
709 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
1550 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
710 | |
1551 | |
711 | This function combines a simple timer and an I/O watcher, calls your |
1552 | This function combines a simple timer and an I/O watcher, calls your |
712 | callback on whichever event happens first and automatically stop both |
1553 | callback on whichever event happens first and automatically stop both |
713 | watchers. This is useful if you want to wait for a single event on an fd |
1554 | watchers. This is useful if you want to wait for a single event on an fd |
714 | or timeout without havign to allocate/configure/start/stop/free one or |
1555 | or timeout without having to allocate/configure/start/stop/free one or |
715 | more watchers yourself. |
1556 | more watchers yourself. |
716 | |
1557 | |
717 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
1558 | If C<fd> is less than 0, then no I/O watcher will be started and events |
718 | ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and C<events> set |
1559 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
719 | will be craeted and started. |
1560 | C<events> set will be craeted and started. |
720 | |
1561 | |
721 | If C<timeout> is less than 0, then no timeout watcher will be |
1562 | If C<timeout> is less than 0, then no timeout watcher will be |
722 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and repeat |
1563 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
723 | = 0) will be started. |
1564 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
|
|
1565 | dubious value. |
724 | |
1566 | |
725 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
1567 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
726 | gets passed an events set (normally a combination of C<EV_ERROR>, C<EV_READ>, |
1568 | passed an C<revents> set like normal event callbacks (a combination of |
727 | C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> value passed to C<ev_once>: |
1569 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
|
|
1570 | value passed to C<ev_once>: |
728 | |
1571 | |
729 | static void stdin_ready (int revents, void *arg) |
1572 | static void stdin_ready (int revents, void *arg) |
730 | { |
1573 | { |
731 | if (revents & EV_TIMEOUT) |
1574 | if (revents & EV_TIMEOUT) |
732 | /* doh, nothing entered */ |
1575 | /* doh, nothing entered */; |
733 | else if (revents & EV_READ) |
1576 | else if (revents & EV_READ) |
734 | /* stdin might have data for us, joy! */ |
1577 | /* stdin might have data for us, joy! */; |
735 | } |
1578 | } |
736 | |
1579 | |
737 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
1580 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
738 | |
1581 | |
739 | =item ev_feed_event (loop, watcher, int events) |
1582 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
740 | |
1583 | |
741 | Feeds the given event set into the event loop, as if the specified event |
1584 | Feeds the given event set into the event loop, as if the specified event |
742 | has happened for the specified watcher (which must be a pointer to an |
1585 | had happened for the specified watcher (which must be a pointer to an |
743 | initialised but not necessarily active event watcher). |
1586 | initialised but not necessarily started event watcher). |
744 | |
1587 | |
745 | =item ev_feed_fd_event (loop, int fd, int revents) |
1588 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
746 | |
1589 | |
747 | Feed an event on the given fd, as if a file descriptor backend detected it. |
1590 | Feed an event on the given fd, as if a file descriptor backend detected |
|
|
1591 | the given events it. |
748 | |
1592 | |
749 | =item ev_feed_signal_event (loop, int signum) |
1593 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
750 | |
1594 | |
751 | Feed an event as if the given signal occured (loop must be the default loop!). |
1595 | Feed an event as if the given signal occured (C<loop> must be the default |
|
|
1596 | loop!). |
752 | |
1597 | |
753 | =back |
1598 | =back |
754 | |
1599 | |
|
|
1600 | |
|
|
1601 | =head1 LIBEVENT EMULATION |
|
|
1602 | |
|
|
1603 | Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
1604 | emulate the internals of libevent, so here are some usage hints: |
|
|
1605 | |
|
|
1606 | =over 4 |
|
|
1607 | |
|
|
1608 | =item * Use it by including <event.h>, as usual. |
|
|
1609 | |
|
|
1610 | =item * The following members are fully supported: ev_base, ev_callback, |
|
|
1611 | ev_arg, ev_fd, ev_res, ev_events. |
|
|
1612 | |
|
|
1613 | =item * Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
1614 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
1615 | it a private API). |
|
|
1616 | |
|
|
1617 | =item * Priorities are not currently supported. Initialising priorities |
|
|
1618 | will fail and all watchers will have the same priority, even though there |
|
|
1619 | is an ev_pri field. |
|
|
1620 | |
|
|
1621 | =item * Other members are not supported. |
|
|
1622 | |
|
|
1623 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
|
|
1624 | to use the libev header file and library. |
|
|
1625 | |
|
|
1626 | =back |
|
|
1627 | |
|
|
1628 | =head1 C++ SUPPORT |
|
|
1629 | |
|
|
1630 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1631 | you to use some convinience methods to start/stop watchers and also change |
|
|
1632 | the callback model to a model using method callbacks on objects. |
|
|
1633 | |
|
|
1634 | To use it, |
|
|
1635 | |
|
|
1636 | #include <ev++.h> |
|
|
1637 | |
|
|
1638 | (it is not installed by default). This automatically includes F<ev.h> |
|
|
1639 | and puts all of its definitions (many of them macros) into the global |
|
|
1640 | namespace. All C++ specific things are put into the C<ev> namespace. |
|
|
1641 | |
|
|
1642 | It should support all the same embedding options as F<ev.h>, most notably |
|
|
1643 | C<EV_MULTIPLICITY>. |
|
|
1644 | |
|
|
1645 | Here is a list of things available in the C<ev> namespace: |
|
|
1646 | |
|
|
1647 | =over 4 |
|
|
1648 | |
|
|
1649 | =item C<ev::READ>, C<ev::WRITE> etc. |
|
|
1650 | |
|
|
1651 | These are just enum values with the same values as the C<EV_READ> etc. |
|
|
1652 | macros from F<ev.h>. |
|
|
1653 | |
|
|
1654 | =item C<ev::tstamp>, C<ev::now> |
|
|
1655 | |
|
|
1656 | Aliases to the same types/functions as with the C<ev_> prefix. |
|
|
1657 | |
|
|
1658 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
|
|
1659 | |
|
|
1660 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
|
|
1661 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
|
|
1662 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
|
|
1663 | defines by many implementations. |
|
|
1664 | |
|
|
1665 | All of those classes have these methods: |
|
|
1666 | |
|
|
1667 | =over 4 |
|
|
1668 | |
|
|
1669 | =item ev::TYPE::TYPE (object *, object::method *) |
|
|
1670 | |
|
|
1671 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
|
|
1672 | |
|
|
1673 | =item ev::TYPE::~TYPE |
|
|
1674 | |
|
|
1675 | The constructor takes a pointer to an object and a method pointer to |
|
|
1676 | the event handler callback to call in this class. The constructor calls |
|
|
1677 | C<ev_init> for you, which means you have to call the C<set> method |
|
|
1678 | before starting it. If you do not specify a loop then the constructor |
|
|
1679 | automatically associates the default loop with this watcher. |
|
|
1680 | |
|
|
1681 | The destructor automatically stops the watcher if it is active. |
|
|
1682 | |
|
|
1683 | =item w->set (struct ev_loop *) |
|
|
1684 | |
|
|
1685 | Associates a different C<struct ev_loop> with this watcher. You can only |
|
|
1686 | do this when the watcher is inactive (and not pending either). |
|
|
1687 | |
|
|
1688 | =item w->set ([args]) |
|
|
1689 | |
|
|
1690 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
|
|
1691 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1692 | automatically stopped and restarted. |
|
|
1693 | |
|
|
1694 | =item w->start () |
|
|
1695 | |
|
|
1696 | Starts the watcher. Note that there is no C<loop> argument as the |
|
|
1697 | constructor already takes the loop. |
|
|
1698 | |
|
|
1699 | =item w->stop () |
|
|
1700 | |
|
|
1701 | Stops the watcher if it is active. Again, no C<loop> argument. |
|
|
1702 | |
|
|
1703 | =item w->again () C<ev::timer>, C<ev::periodic> only |
|
|
1704 | |
|
|
1705 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
|
|
1706 | C<ev_TYPE_again> function. |
|
|
1707 | |
|
|
1708 | =item w->sweep () C<ev::embed> only |
|
|
1709 | |
|
|
1710 | Invokes C<ev_embed_sweep>. |
|
|
1711 | |
|
|
1712 | =item w->update () C<ev::stat> only |
|
|
1713 | |
|
|
1714 | Invokes C<ev_stat_stat>. |
|
|
1715 | |
|
|
1716 | =back |
|
|
1717 | |
|
|
1718 | =back |
|
|
1719 | |
|
|
1720 | Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1721 | the constructor. |
|
|
1722 | |
|
|
1723 | class myclass |
|
|
1724 | { |
|
|
1725 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1726 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1727 | |
|
|
1728 | myclass (); |
|
|
1729 | } |
|
|
1730 | |
|
|
1731 | myclass::myclass (int fd) |
|
|
1732 | : io (this, &myclass::io_cb), |
|
|
1733 | idle (this, &myclass::idle_cb) |
|
|
1734 | { |
|
|
1735 | io.start (fd, ev::READ); |
|
|
1736 | } |
|
|
1737 | |
|
|
1738 | |
|
|
1739 | =head1 MACRO MAGIC |
|
|
1740 | |
|
|
1741 | Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1742 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
|
|
1743 | callbacks have an initial C<struct ev_loop *> argument. |
|
|
1744 | |
|
|
1745 | To make it easier to write programs that cope with either variant, the |
|
|
1746 | following macros are defined: |
|
|
1747 | |
|
|
1748 | =over 4 |
|
|
1749 | |
|
|
1750 | =item C<EV_A>, C<EV_A_> |
|
|
1751 | |
|
|
1752 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
1753 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
1754 | C<EV_A_> is used when other arguments are following. Example: |
|
|
1755 | |
|
|
1756 | ev_unref (EV_A); |
|
|
1757 | ev_timer_add (EV_A_ watcher); |
|
|
1758 | ev_loop (EV_A_ 0); |
|
|
1759 | |
|
|
1760 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
1761 | which is often provided by the following macro. |
|
|
1762 | |
|
|
1763 | =item C<EV_P>, C<EV_P_> |
|
|
1764 | |
|
|
1765 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
1766 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
1767 | C<EV_P_> is used when other parameters are following. Example: |
|
|
1768 | |
|
|
1769 | // this is how ev_unref is being declared |
|
|
1770 | static void ev_unref (EV_P); |
|
|
1771 | |
|
|
1772 | // this is how you can declare your typical callback |
|
|
1773 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1774 | |
|
|
1775 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
1776 | suitable for use with C<EV_A>. |
|
|
1777 | |
|
|
1778 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
1779 | |
|
|
1780 | Similar to the other two macros, this gives you the value of the default |
|
|
1781 | loop, if multiple loops are supported ("ev loop default"). |
|
|
1782 | |
|
|
1783 | =back |
|
|
1784 | |
|
|
1785 | Example: Declare and initialise a check watcher, working regardless of |
|
|
1786 | wether multiple loops are supported or not. |
|
|
1787 | |
|
|
1788 | static void |
|
|
1789 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1790 | { |
|
|
1791 | ev_check_stop (EV_A_ w); |
|
|
1792 | } |
|
|
1793 | |
|
|
1794 | ev_check check; |
|
|
1795 | ev_check_init (&check, check_cb); |
|
|
1796 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1797 | ev_loop (EV_DEFAULT_ 0); |
|
|
1798 | |
|
|
1799 | |
|
|
1800 | =head1 EMBEDDING |
|
|
1801 | |
|
|
1802 | Libev can (and often is) directly embedded into host |
|
|
1803 | applications. Examples of applications that embed it include the Deliantra |
|
|
1804 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1805 | and rxvt-unicode. |
|
|
1806 | |
|
|
1807 | The goal is to enable you to just copy the neecssary files into your |
|
|
1808 | source directory without having to change even a single line in them, so |
|
|
1809 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1810 | libev somewhere in your source tree). |
|
|
1811 | |
|
|
1812 | =head2 FILESETS |
|
|
1813 | |
|
|
1814 | Depending on what features you need you need to include one or more sets of files |
|
|
1815 | in your app. |
|
|
1816 | |
|
|
1817 | =head3 CORE EVENT LOOP |
|
|
1818 | |
|
|
1819 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
1820 | configuration (no autoconf): |
|
|
1821 | |
|
|
1822 | #define EV_STANDALONE 1 |
|
|
1823 | #include "ev.c" |
|
|
1824 | |
|
|
1825 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
1826 | single C source file only to provide the function implementations. To use |
|
|
1827 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
1828 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
1829 | where you can put other configuration options): |
|
|
1830 | |
|
|
1831 | #define EV_STANDALONE 1 |
|
|
1832 | #include "ev.h" |
|
|
1833 | |
|
|
1834 | Both header files and implementation files can be compiled with a C++ |
|
|
1835 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1836 | as a bug). |
|
|
1837 | |
|
|
1838 | You need the following files in your source tree, or in a directory |
|
|
1839 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
1840 | |
|
|
1841 | ev.h |
|
|
1842 | ev.c |
|
|
1843 | ev_vars.h |
|
|
1844 | ev_wrap.h |
|
|
1845 | |
|
|
1846 | ev_win32.c required on win32 platforms only |
|
|
1847 | |
|
|
1848 | ev_select.c only when select backend is enabled (which is by default) |
|
|
1849 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1850 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1851 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1852 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1853 | |
|
|
1854 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
1855 | to compile this single file. |
|
|
1856 | |
|
|
1857 | =head3 LIBEVENT COMPATIBILITY API |
|
|
1858 | |
|
|
1859 | To include the libevent compatibility API, also include: |
|
|
1860 | |
|
|
1861 | #include "event.c" |
|
|
1862 | |
|
|
1863 | in the file including F<ev.c>, and: |
|
|
1864 | |
|
|
1865 | #include "event.h" |
|
|
1866 | |
|
|
1867 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
1868 | |
|
|
1869 | You need the following additional files for this: |
|
|
1870 | |
|
|
1871 | event.h |
|
|
1872 | event.c |
|
|
1873 | |
|
|
1874 | =head3 AUTOCONF SUPPORT |
|
|
1875 | |
|
|
1876 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
1877 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
1878 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
|
|
1879 | include F<config.h> and configure itself accordingly. |
|
|
1880 | |
|
|
1881 | For this of course you need the m4 file: |
|
|
1882 | |
|
|
1883 | libev.m4 |
|
|
1884 | |
|
|
1885 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
1886 | |
|
|
1887 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1888 | before including any of its files. The default is not to build for multiplicity |
|
|
1889 | and only include the select backend. |
|
|
1890 | |
|
|
1891 | =over 4 |
|
|
1892 | |
|
|
1893 | =item EV_STANDALONE |
|
|
1894 | |
|
|
1895 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
1896 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
1897 | implementations for some libevent functions (such as logging, which is not |
|
|
1898 | supported). It will also not define any of the structs usually found in |
|
|
1899 | F<event.h> that are not directly supported by the libev core alone. |
|
|
1900 | |
|
|
1901 | =item EV_USE_MONOTONIC |
|
|
1902 | |
|
|
1903 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1904 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1905 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1906 | usually have to link against librt or something similar. Enabling it when |
|
|
1907 | the functionality isn't available is safe, though, althoguh you have |
|
|
1908 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
1909 | function is hiding in (often F<-lrt>). |
|
|
1910 | |
|
|
1911 | =item EV_USE_REALTIME |
|
|
1912 | |
|
|
1913 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1914 | realtime clock option at compiletime (and assume its availability at |
|
|
1915 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1916 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
1917 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
|
|
1918 | in the description of C<EV_USE_MONOTONIC>, though. |
|
|
1919 | |
|
|
1920 | =item EV_USE_SELECT |
|
|
1921 | |
|
|
1922 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
1923 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
1924 | other method takes over, select will be it. Otherwise the select backend |
|
|
1925 | will not be compiled in. |
|
|
1926 | |
|
|
1927 | =item EV_SELECT_USE_FD_SET |
|
|
1928 | |
|
|
1929 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
1930 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1931 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
1932 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1933 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1934 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
1935 | influence the size of the C<fd_set> used. |
|
|
1936 | |
|
|
1937 | =item EV_SELECT_IS_WINSOCKET |
|
|
1938 | |
|
|
1939 | When defined to C<1>, the select backend will assume that |
|
|
1940 | select/socket/connect etc. don't understand file descriptors but |
|
|
1941 | wants osf handles on win32 (this is the case when the select to |
|
|
1942 | be used is the winsock select). This means that it will call |
|
|
1943 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
1944 | it is assumed that all these functions actually work on fds, even |
|
|
1945 | on win32. Should not be defined on non-win32 platforms. |
|
|
1946 | |
|
|
1947 | =item EV_USE_POLL |
|
|
1948 | |
|
|
1949 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
1950 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1951 | takes precedence over select. |
|
|
1952 | |
|
|
1953 | =item EV_USE_EPOLL |
|
|
1954 | |
|
|
1955 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
1956 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
1957 | otherwise another method will be used as fallback. This is the |
|
|
1958 | preferred backend for GNU/Linux systems. |
|
|
1959 | |
|
|
1960 | =item EV_USE_KQUEUE |
|
|
1961 | |
|
|
1962 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
1963 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
1964 | otherwise another method will be used as fallback. This is the preferred |
|
|
1965 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
1966 | supports some types of fds correctly (the only platform we found that |
|
|
1967 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
1968 | not be used unless explicitly requested. The best way to use it is to find |
|
|
1969 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
1970 | kqueue loop. |
|
|
1971 | |
|
|
1972 | =item EV_USE_PORT |
|
|
1973 | |
|
|
1974 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
1975 | 10 port style backend. Its availability will be detected at runtime, |
|
|
1976 | otherwise another method will be used as fallback. This is the preferred |
|
|
1977 | backend for Solaris 10 systems. |
|
|
1978 | |
|
|
1979 | =item EV_USE_DEVPOLL |
|
|
1980 | |
|
|
1981 | reserved for future expansion, works like the USE symbols above. |
|
|
1982 | |
|
|
1983 | =item EV_H |
|
|
1984 | |
|
|
1985 | The name of the F<ev.h> header file used to include it. The default if |
|
|
1986 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
|
|
1987 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
1988 | |
|
|
1989 | =item EV_CONFIG_H |
|
|
1990 | |
|
|
1991 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
1992 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
1993 | C<EV_H>, above. |
|
|
1994 | |
|
|
1995 | =item EV_EVENT_H |
|
|
1996 | |
|
|
1997 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
1998 | of how the F<event.h> header can be found. |
|
|
1999 | |
|
|
2000 | =item EV_PROTOTYPES |
|
|
2001 | |
|
|
2002 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
2003 | prototypes, but still define all the structs and other symbols. This is |
|
|
2004 | occasionally useful if you want to provide your own wrapper functions |
|
|
2005 | around libev functions. |
|
|
2006 | |
|
|
2007 | =item EV_MULTIPLICITY |
|
|
2008 | |
|
|
2009 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
2010 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
2011 | additional independent event loops. Otherwise there will be no support |
|
|
2012 | for multiple event loops and there is no first event loop pointer |
|
|
2013 | argument. Instead, all functions act on the single default loop. |
|
|
2014 | |
|
|
2015 | =item EV_PERIODIC_ENABLE |
|
|
2016 | |
|
|
2017 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2018 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2019 | code. |
|
|
2020 | |
|
|
2021 | =item EV_EMBED_ENABLE |
|
|
2022 | |
|
|
2023 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2024 | defined to be C<0>, then they are not. |
|
|
2025 | |
|
|
2026 | =item EV_STAT_ENABLE |
|
|
2027 | |
|
|
2028 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2029 | defined to be C<0>, then they are not. |
|
|
2030 | |
|
|
2031 | =item EV_FORK_ENABLE |
|
|
2032 | |
|
|
2033 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2034 | defined to be C<0>, then they are not. |
|
|
2035 | |
|
|
2036 | =item EV_MINIMAL |
|
|
2037 | |
|
|
2038 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2039 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
2040 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2041 | |
|
|
2042 | =item EV_PID_HASHSIZE |
|
|
2043 | |
|
|
2044 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2045 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2046 | than enough. If you need to manage thousands of children you might want to |
|
|
2047 | increase this value. |
|
|
2048 | |
|
|
2049 | =item EV_COMMON |
|
|
2050 | |
|
|
2051 | By default, all watchers have a C<void *data> member. By redefining |
|
|
2052 | this macro to a something else you can include more and other types of |
|
|
2053 | members. You have to define it each time you include one of the files, |
|
|
2054 | though, and it must be identical each time. |
|
|
2055 | |
|
|
2056 | For example, the perl EV module uses something like this: |
|
|
2057 | |
|
|
2058 | #define EV_COMMON \ |
|
|
2059 | SV *self; /* contains this struct */ \ |
|
|
2060 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2061 | |
|
|
2062 | =item EV_CB_DECLARE (type) |
|
|
2063 | |
|
|
2064 | =item EV_CB_INVOKE (watcher, revents) |
|
|
2065 | |
|
|
2066 | =item ev_set_cb (ev, cb) |
|
|
2067 | |
|
|
2068 | Can be used to change the callback member declaration in each watcher, |
|
|
2069 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2070 | definition and a statement, respectively. See the F<ev.v> header file for |
|
|
2071 | their default definitions. One possible use for overriding these is to |
|
|
2072 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
|
|
2073 | method calls instead of plain function calls in C++. |
|
|
2074 | |
|
|
2075 | =head2 EXAMPLES |
|
|
2076 | |
|
|
2077 | For a real-world example of a program the includes libev |
|
|
2078 | verbatim, you can have a look at the EV perl module |
|
|
2079 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
2080 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
2081 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
2082 | will be compiled. It is pretty complex because it provides its own header |
|
|
2083 | file. |
|
|
2084 | |
|
|
2085 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
2086 | that everybody includes and which overrides some autoconf choices: |
|
|
2087 | |
|
|
2088 | #define EV_USE_POLL 0 |
|
|
2089 | #define EV_MULTIPLICITY 0 |
|
|
2090 | #define EV_PERIODICS 0 |
|
|
2091 | #define EV_CONFIG_H <config.h> |
|
|
2092 | |
|
|
2093 | #include "ev++.h" |
|
|
2094 | |
|
|
2095 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
2096 | |
|
|
2097 | #include "ev_cpp.h" |
|
|
2098 | #include "ev.c" |
|
|
2099 | |
|
|
2100 | |
|
|
2101 | =head1 COMPLEXITIES |
|
|
2102 | |
|
|
2103 | In this section the complexities of (many of) the algorithms used inside |
|
|
2104 | libev will be explained. For complexity discussions about backends see the |
|
|
2105 | documentation for C<ev_default_init>. |
|
|
2106 | |
|
|
2107 | =over 4 |
|
|
2108 | |
|
|
2109 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
2110 | |
|
|
2111 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
2112 | |
|
|
2113 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
2114 | |
|
|
2115 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
2116 | |
|
|
2117 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
|
|
2118 | |
|
|
2119 | =item Finding the next timer per loop iteration: O(1) |
|
|
2120 | |
|
|
2121 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
2122 | |
|
|
2123 | =item Activating one watcher: O(1) |
|
|
2124 | |
|
|
2125 | =back |
|
|
2126 | |
|
|
2127 | |
755 | =head1 AUTHOR |
2128 | =head1 AUTHOR |
756 | |
2129 | |
757 | Marc Lehmann <libev@schmorp.de>. |
2130 | Marc Lehmann <libev@schmorp.de>. |
758 | |
2131 | |