… | |
… | |
39 | F<README.embed> in the libev distribution. If libev was configured without |
39 | F<README.embed> in the libev distribution. If libev was configured without |
40 | support for multiple event loops, then all functions taking an initial |
40 | 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 *>) |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
42 | will not have this argument. |
42 | will not have this argument. |
43 | |
43 | |
44 | =head1 TIME AND OTHER GLOBAL FUNCTIONS |
44 | =head1 TIME REPRESENTATION |
45 | |
45 | |
46 | Libev represents time as a single floating point number, representing the |
46 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
48 | 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 |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
50 | to the C<double> type in C, and when you need to do any calculations on |
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51 | it, you should treat it as such. |
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52 | |
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53 | |
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54 | =head1 GLOBAL FUNCTIONS |
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55 | |
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56 | These functions can be called anytime, even before initialising the |
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57 | library in any way. |
51 | |
58 | |
52 | =over 4 |
59 | =over 4 |
53 | |
60 | |
54 | =item ev_tstamp ev_time () |
61 | =item ev_tstamp ev_time () |
55 | |
62 | |
56 | Returns the current time as libev would use it. |
63 | Returns the current time as libev would use it. Please note that the |
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64 | C<ev_now> function is usually faster and also often returns the timestamp |
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65 | you actually want to know. |
57 | |
66 | |
58 | =item int ev_version_major () |
67 | =item int ev_version_major () |
59 | |
68 | |
60 | =item int ev_version_minor () |
69 | =item int ev_version_minor () |
61 | |
70 | |
… | |
… | |
68 | Usually, it's a good idea to terminate if the major versions mismatch, |
77 | Usually, it's a good idea to terminate if the major versions mismatch, |
69 | as this indicates an incompatible change. Minor versions are usually |
78 | as this indicates an incompatible change. Minor versions are usually |
70 | compatible to older versions, so a larger minor version alone is usually |
79 | compatible to older versions, so a larger minor version alone is usually |
71 | not a problem. |
80 | not a problem. |
72 | |
81 | |
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82 | Example: make sure we haven't accidentally been linked against the wrong |
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83 | version: |
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84 | |
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85 | assert (("libev version mismatch", |
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86 | ev_version_major () == EV_VERSION_MAJOR |
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87 | && ev_version_minor () >= EV_VERSION_MINOR)); |
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88 | |
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89 | =item unsigned int ev_supported_backends () |
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90 | |
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91 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
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92 | value) compiled into this binary of libev (independent of their |
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93 | availability on the system you are running on). See C<ev_default_loop> for |
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94 | a description of the set values. |
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95 | |
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96 | Example: make sure we have the epoll method, because yeah this is cool and |
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97 | a must have and can we have a torrent of it please!!!11 |
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98 | |
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99 | assert (("sorry, no epoll, no sex", |
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100 | ev_supported_backends () & EVBACKEND_EPOLL)); |
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101 | |
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102 | =item unsigned int ev_recommended_backends () |
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103 | |
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104 | Return the set of all backends compiled into this binary of libev and also |
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105 | recommended for this platform. This set is often smaller than the one |
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106 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
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107 | most BSDs and will not be autodetected unless you explicitly request it |
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108 | (assuming you know what you are doing). This is the set of backends that |
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109 | libev will probe for if you specify no backends explicitly. |
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110 | |
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111 | =item unsigned int ev_embeddable_backends () |
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112 | |
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113 | Returns the set of backends that are embeddable in other event loops. This |
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114 | is the theoretical, all-platform, value. To find which backends |
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115 | might be supported on the current system, you would need to look at |
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116 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
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117 | recommended ones. |
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118 | |
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119 | See the description of C<ev_embed> watchers for more info. |
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120 | |
73 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
121 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
74 | |
122 | |
75 | Sets the allocation function to use (the prototype is similar to the |
123 | Sets the allocation function to use (the prototype is similar to the |
76 | realloc C function, the semantics are identical). It is used to allocate |
124 | realloc C function, the semantics are identical). It is used to allocate |
77 | and free memory (no surprises here). If it returns zero when memory |
125 | and free memory (no surprises here). If it returns zero when memory |
… | |
… | |
79 | destructive action. The default is your system realloc function. |
127 | destructive action. The default is your system realloc function. |
80 | |
128 | |
81 | You could override this function in high-availability programs to, say, |
129 | 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, |
130 | 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. |
131 | or even to sleep a while and retry until some memory is available. |
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132 | |
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133 | Example: replace the libev allocator with one that waits a bit and then |
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134 | retries: better than mine). |
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135 | |
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136 | static void * |
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137 | persistent_realloc (void *ptr, long size) |
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138 | { |
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139 | for (;;) |
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140 | { |
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141 | void *newptr = realloc (ptr, size); |
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142 | |
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143 | if (newptr) |
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144 | return newptr; |
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145 | |
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146 | sleep (60); |
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147 | } |
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148 | } |
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149 | |
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150 | ... |
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151 | ev_set_allocator (persistent_realloc); |
84 | |
152 | |
85 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
153 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
86 | |
154 | |
87 | Set the callback function to call on a retryable syscall error (such |
155 | 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 |
156 | as failed select, poll, epoll_wait). The message is a printable string |
… | |
… | |
90 | callback is set, then libev will expect it to remedy the sitution, no |
158 | 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 |
159 | 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 |
160 | requested operation, or, if the condition doesn't go away, do bad stuff |
93 | (such as abort). |
161 | (such as abort). |
94 | |
162 | |
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163 | Example: do the same thing as libev does internally: |
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164 | |
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165 | static void |
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166 | fatal_error (const char *msg) |
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167 | { |
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168 | perror (msg); |
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169 | abort (); |
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170 | } |
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171 | |
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172 | ... |
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173 | ev_set_syserr_cb (fatal_error); |
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174 | |
95 | =back |
175 | =back |
96 | |
176 | |
97 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
177 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
98 | |
178 | |
99 | An event loop is described by a C<struct ev_loop *>. The library knows two |
179 | 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 |
180 | types of such loops, the I<default> loop, which supports signals and child |
101 | events, and dynamically created loops which do not. |
181 | events, and dynamically created loops which do not. |
102 | |
182 | |
103 | If you use threads, a common model is to run the default event loop |
183 | 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 |
184 | 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 |
185 | 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 |
186 | 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 |
187 | threads, make sure you lock (this is usually a bad idea, though, even if |
108 | done correctly, because it's hideous and inefficient). |
188 | done correctly, because it's hideous and inefficient). |
109 | |
189 | |
… | |
… | |
112 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
192 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
113 | |
193 | |
114 | This will initialise the default event loop if it hasn't been initialised |
194 | 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 |
195 | 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 |
196 | false. If it already was initialised it simply returns it (and ignores the |
117 | flags). |
197 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
118 | |
198 | |
119 | If you don't know what event loop to use, use the one returned from this |
199 | If you don't know what event loop to use, use the one returned from this |
120 | function. |
200 | function. |
121 | |
201 | |
122 | The flags argument can be used to specify special behaviour or specific |
202 | 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). |
203 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
124 | |
204 | |
125 | It supports the following flags: |
205 | The following flags are supported: |
126 | |
206 | |
127 | =over 4 |
207 | =over 4 |
128 | |
208 | |
129 | =item C<EVFLAG_AUTO> |
209 | =item C<EVFLAG_AUTO> |
130 | |
210 | |
… | |
… | |
138 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
218 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
139 | override the flags completely if it is found in the environment. This is |
219 | 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 |
220 | useful to try out specific backends to test their performance, or to work |
141 | around bugs. |
221 | around bugs. |
142 | |
222 | |
143 | =item C<EVMETHOD_SELECT> (portable select backend) |
223 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
144 | |
224 | |
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225 | This is your standard select(2) backend. Not I<completely> standard, as |
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226 | libev tries to roll its own fd_set with no limits on the number of fds, |
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227 | but if that fails, expect a fairly low limit on the number of fds when |
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228 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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229 | the fastest backend for a low number of fds. |
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230 | |
145 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
231 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
146 | |
232 | |
147 | =item C<EVMETHOD_EPOLL> (linux only) |
233 | And this is your standard poll(2) backend. It's more complicated than |
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234 | select, but handles sparse fds better and has no artificial limit on the |
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235 | number of fds you can use (except it will slow down considerably with a |
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236 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
148 | |
237 | |
149 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
238 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
150 | |
239 | |
151 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
240 | For few fds, this backend is a bit little slower than poll and select, |
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241 | but it scales phenomenally better. While poll and select usually scale like |
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242 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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243 | either O(1) or O(active_fds). |
152 | |
244 | |
153 | =item C<EVMETHOD_PORT> (solaris 10 only) |
245 | While stopping and starting an I/O watcher in the same iteration will |
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246 | result in some caching, there is still a syscall per such incident |
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247 | (because the fd could point to a different file description now), so its |
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248 | best to avoid that. Also, dup()ed file descriptors might not work very |
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249 | well if you register events for both fds. |
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250 | |
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251 | Please note that epoll sometimes generates spurious notifications, so you |
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252 | need to use non-blocking I/O or other means to avoid blocking when no data |
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253 | (or space) is available. |
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254 | |
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255 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
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256 | |
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257 | Kqueue deserves special mention, as at the time of this writing, it |
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258 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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259 | anything but sockets and pipes, except on Darwin, where of course its |
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260 | completely useless). For this reason its not being "autodetected" |
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261 | unless you explicitly specify it explicitly in the flags (i.e. using |
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262 | C<EVBACKEND_KQUEUE>). |
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263 | |
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264 | It scales in the same way as the epoll backend, but the interface to the |
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265 | kernel is more efficient (which says nothing about its actual speed, of |
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266 | course). While starting and stopping an I/O watcher does not cause an |
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267 | extra syscall as with epoll, it still adds up to four event changes per |
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268 | incident, so its best to avoid that. |
|
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269 | |
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270 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
|
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271 | |
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272 | This is not implemented yet (and might never be). |
|
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273 | |
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274 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
|
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275 | |
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276 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
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277 | it's really slow, but it still scales very well (O(active_fds)). |
|
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278 | |
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279 | Please note that solaris ports can result in a lot of spurious |
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280 | notifications, so you need to use non-blocking I/O or other means to avoid |
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281 | blocking when no data (or space) is available. |
|
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282 | |
|
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283 | =item C<EVBACKEND_ALL> |
|
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284 | |
|
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285 | Try all backends (even potentially broken ones that wouldn't be tried |
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286 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
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287 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
|
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288 | |
|
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289 | =back |
154 | |
290 | |
155 | If one or more of these are ored into the flags value, then only these |
291 | 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 |
292 | backends will be tried (in the reverse order as given here). If none are |
157 | specified, any backend will do. |
293 | specified, most compiled-in backend will be tried, usually in reverse |
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294 | order of their flag values :) |
158 | |
295 | |
159 | =back |
296 | The most typical usage is like this: |
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297 | |
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298 | if (!ev_default_loop (0)) |
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299 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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300 | |
|
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301 | Restrict libev to the select and poll backends, and do not allow |
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302 | environment settings to be taken into account: |
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303 | |
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304 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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305 | |
|
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306 | Use whatever libev has to offer, but make sure that kqueue is used if |
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307 | available (warning, breaks stuff, best use only with your own private |
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308 | event loop and only if you know the OS supports your types of fds): |
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309 | |
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310 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
160 | |
311 | |
161 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
312 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
162 | |
313 | |
163 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
314 | 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 |
315 | 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 |
316 | 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). |
317 | undefined behaviour (or a failed assertion if assertions are enabled). |
167 | |
318 | |
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319 | Example: try to create a event loop that uses epoll and nothing else. |
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320 | |
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321 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
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322 | if (!epoller) |
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323 | fatal ("no epoll found here, maybe it hides under your chair"); |
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324 | |
168 | =item ev_default_destroy () |
325 | =item ev_default_destroy () |
169 | |
326 | |
170 | Destroys the default loop again (frees all memory and kernel state |
327 | Destroys the default loop again (frees all memory and kernel state |
171 | etc.). This stops all registered event watchers (by not touching them in |
328 | etc.). None of the active event watchers will be stopped in the normal |
172 | any way whatsoever, although you cannot rely on this :). |
329 | sense, so e.g. C<ev_is_active> might still return true. It is your |
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330 | responsibility to either stop all watchers cleanly yoursef I<before> |
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331 | calling this function, or cope with the fact afterwards (which is usually |
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332 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
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333 | for example). |
173 | |
334 | |
174 | =item ev_loop_destroy (loop) |
335 | =item ev_loop_destroy (loop) |
175 | |
336 | |
176 | Like C<ev_default_destroy>, but destroys an event loop created by an |
337 | Like C<ev_default_destroy>, but destroys an event loop created by an |
177 | earlier call to C<ev_loop_new>. |
338 | earlier call to C<ev_loop_new>. |
… | |
… | |
181 | This function reinitialises the kernel state for backends that have |
342 | 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 |
343 | 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 |
344 | after forking, in either the parent or child process (or both, but that |
184 | again makes little sense). |
345 | again makes little sense). |
185 | |
346 | |
186 | You I<must> call this function after forking if and only if you want to |
347 | 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 |
348 | only if you want to use the event library in both processes. If you just |
188 | have to call it. |
349 | fork+exec, you don't have to call it. |
189 | |
350 | |
190 | The function itself is quite fast and it's usually not a problem to call |
351 | 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 |
352 | 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>: |
353 | quite nicely into a call to C<pthread_atfork>: |
193 | |
354 | |
194 | pthread_atfork (0, 0, ev_default_fork); |
355 | pthread_atfork (0, 0, ev_default_fork); |
195 | |
356 | |
|
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357 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
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358 | without calling this function, so if you force one of those backends you |
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359 | do not need to care. |
|
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360 | |
196 | =item ev_loop_fork (loop) |
361 | =item ev_loop_fork (loop) |
197 | |
362 | |
198 | Like C<ev_default_fork>, but acts on an event loop created by |
363 | 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 |
364 | 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. |
365 | after fork, and how you do this is entirely your own problem. |
201 | |
366 | |
202 | =item unsigned int ev_method (loop) |
367 | =item unsigned int ev_backend (loop) |
203 | |
368 | |
204 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
369 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
205 | use. |
370 | use. |
206 | |
371 | |
207 | =item ev_tstamp ev_now (loop) |
372 | =item ev_tstamp ev_now (loop) |
208 | |
373 | |
209 | Returns the current "event loop time", which is the time the event loop |
374 | 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 |
375 | 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 |
376 | 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 |
377 | 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). |
378 | event occuring (or more correctly, libev finding out about it). |
214 | |
379 | |
215 | =item ev_loop (loop, int flags) |
380 | =item ev_loop (loop, int flags) |
216 | |
381 | |
217 | Finally, this is it, the event handler. This function usually is called |
382 | 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 |
383 | after you initialised all your watchers and you want to start handling |
219 | events. |
384 | events. |
220 | |
385 | |
221 | If the flags argument is specified as 0, it will not return until either |
386 | 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. |
387 | either no event watchers are active anymore or C<ev_unloop> was called. |
|
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388 | |
|
|
389 | Please note that an explicit C<ev_unloop> is usually better than |
|
|
390 | relying on all watchers to be stopped when deciding when a program has |
|
|
391 | finished (especially in interactive programs), but having a program that |
|
|
392 | automatically loops as long as it has to and no longer by virtue of |
|
|
393 | relying on its watchers stopping correctly is a thing of beauty. |
223 | |
394 | |
224 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
395 | 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 |
396 | 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. |
397 | case there are no events and will return after one iteration of the loop. |
227 | |
398 | |
228 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
399 | 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 |
400 | 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 |
401 | your process until at least one new event arrives, and will return after |
231 | one iteration of the loop. |
402 | one iteration of the loop. This is useful if you are waiting for some |
|
|
403 | external event in conjunction with something not expressible using other |
|
|
404 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
|
|
405 | usually a better approach for this kind of thing. |
232 | |
406 | |
233 | This flags value could be used to implement alternative looping |
407 | 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 |
408 | |
235 | more generic mechanism. |
409 | * If there are no active watchers (reference count is zero), return. |
|
|
410 | - Queue prepare watchers and then call all outstanding watchers. |
|
|
411 | - If we have been forked, recreate the kernel state. |
|
|
412 | - Update the kernel state with all outstanding changes. |
|
|
413 | - Update the "event loop time". |
|
|
414 | - Calculate for how long to block. |
|
|
415 | - Block the process, waiting for any events. |
|
|
416 | - Queue all outstanding I/O (fd) events. |
|
|
417 | - Update the "event loop time" and do time jump handling. |
|
|
418 | - Queue all outstanding timers. |
|
|
419 | - Queue all outstanding periodics. |
|
|
420 | - If no events are pending now, queue all idle watchers. |
|
|
421 | - Queue all check watchers. |
|
|
422 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
423 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
424 | be handled here by queueing them when their watcher gets executed. |
|
|
425 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
|
426 | were used, return, otherwise continue with step *. |
|
|
427 | |
|
|
428 | Example: queue some jobs and then loop until no events are outsanding |
|
|
429 | anymore. |
|
|
430 | |
|
|
431 | ... queue jobs here, make sure they register event watchers as long |
|
|
432 | ... as they still have work to do (even an idle watcher will do..) |
|
|
433 | ev_loop (my_loop, 0); |
|
|
434 | ... jobs done. yeah! |
236 | |
435 | |
237 | =item ev_unloop (loop, how) |
436 | =item ev_unloop (loop, how) |
238 | |
437 | |
239 | Can be used to make a call to C<ev_loop> return early (but only after it |
438 | 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 |
439 | 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 |
440 | 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. |
441 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
243 | |
442 | |
244 | =item ev_ref (loop) |
443 | =item ev_ref (loop) |
245 | |
444 | |
246 | =item ev_unref (loop) |
445 | =item ev_unref (loop) |
… | |
… | |
254 | visible to the libev user and should not keep C<ev_loop> from exiting if |
453 | 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 |
454 | 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 |
455 | 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>. |
456 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
258 | |
457 | |
|
|
458 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
|
|
459 | running when nothing else is active. |
|
|
460 | |
|
|
461 | struct dv_signal exitsig; |
|
|
462 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
463 | ev_signal_start (myloop, &exitsig); |
|
|
464 | evf_unref (myloop); |
|
|
465 | |
|
|
466 | Example: for some weird reason, unregister the above signal handler again. |
|
|
467 | |
|
|
468 | ev_ref (myloop); |
|
|
469 | ev_signal_stop (myloop, &exitsig); |
|
|
470 | |
259 | =back |
471 | =back |
260 | |
472 | |
261 | =head1 ANATOMY OF A WATCHER |
473 | =head1 ANATOMY OF A WATCHER |
262 | |
474 | |
263 | A watcher is a structure that you create and register to record your |
475 | A watcher is a structure that you create and register to record your |
… | |
… | |
297 | *) >>), and you can stop watching for events at any time by calling the |
509 | *) >>), and you can stop watching for events at any time by calling the |
298 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
510 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
299 | |
511 | |
300 | As long as your watcher is active (has been started but not stopped) you |
512 | 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 |
513 | must not touch the values stored in it. Most specifically you must never |
302 | reinitialise it or call its set method. |
514 | 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 | |
515 | |
309 | Each and every callback receives the event loop pointer as first, the |
516 | 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 |
517 | registered watcher structure as second, and a bitset of received events as |
311 | third argument. |
518 | third argument. |
312 | |
519 | |
313 | The rceeived events usually include a single bit per event type received |
520 | 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 |
521 | (you can receive multiple events at the same time). The possible bit masks |
315 | are: |
522 | are: |
316 | |
523 | |
317 | =over 4 |
524 | =over 4 |
318 | |
525 | |
… | |
… | |
369 | with the error from read() or write(). This will not work in multithreaded |
576 | with the error from read() or write(). This will not work in multithreaded |
370 | programs, though, so beware. |
577 | programs, though, so beware. |
371 | |
578 | |
372 | =back |
579 | =back |
373 | |
580 | |
|
|
581 | =head2 SUMMARY OF GENERIC WATCHER FUNCTIONS |
|
|
582 | |
|
|
583 | In the following description, C<TYPE> stands for the watcher type, |
|
|
584 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
|
|
585 | |
|
|
586 | =over 4 |
|
|
587 | |
|
|
588 | =item C<ev_init> (ev_TYPE *watcher, callback) |
|
|
589 | |
|
|
590 | This macro initialises the generic portion of a watcher. The contents |
|
|
591 | of the watcher object can be arbitrary (so C<malloc> will do). Only |
|
|
592 | the generic parts of the watcher are initialised, you I<need> to call |
|
|
593 | the type-specific C<ev_TYPE_set> macro afterwards to initialise the |
|
|
594 | type-specific parts. For each type there is also a C<ev_TYPE_init> macro |
|
|
595 | which rolls both calls into one. |
|
|
596 | |
|
|
597 | You can reinitialise a watcher at any time as long as it has been stopped |
|
|
598 | (or never started) and there are no pending events outstanding. |
|
|
599 | |
|
|
600 | The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
601 | int revents)>. |
|
|
602 | |
|
|
603 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
|
|
604 | |
|
|
605 | This macro initialises the type-specific parts of a watcher. You need to |
|
|
606 | call C<ev_init> at least once before you call this macro, but you can |
|
|
607 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
|
|
608 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
609 | difference to the C<ev_init> macro). |
|
|
610 | |
|
|
611 | Although some watcher types do not have type-specific arguments |
|
|
612 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
|
|
613 | |
|
|
614 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
|
|
615 | |
|
|
616 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
|
|
617 | calls into a single call. This is the most convinient method to initialise |
|
|
618 | a watcher. The same limitations apply, of course. |
|
|
619 | |
|
|
620 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
|
|
621 | |
|
|
622 | Starts (activates) the given watcher. Only active watchers will receive |
|
|
623 | events. If the watcher is already active nothing will happen. |
|
|
624 | |
|
|
625 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
|
|
626 | |
|
|
627 | Stops the given watcher again (if active) and clears the pending |
|
|
628 | status. It is possible that stopped watchers are pending (for example, |
|
|
629 | non-repeating timers are being stopped when they become pending), but |
|
|
630 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
|
|
631 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
632 | good idea to always call its C<ev_TYPE_stop> function. |
|
|
633 | |
|
|
634 | =item bool ev_is_active (ev_TYPE *watcher) |
|
|
635 | |
|
|
636 | Returns a true value iff the watcher is active (i.e. it has been started |
|
|
637 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
638 | it. |
|
|
639 | |
|
|
640 | =item bool ev_is_pending (ev_TYPE *watcher) |
|
|
641 | |
|
|
642 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
643 | events but its callback has not yet been invoked). As long as a watcher |
|
|
644 | is pending (but not active) you must not call an init function on it (but |
|
|
645 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
|
|
646 | libev (e.g. you cnanot C<free ()> it). |
|
|
647 | |
|
|
648 | =item callback = ev_cb (ev_TYPE *watcher) |
|
|
649 | |
|
|
650 | Returns the callback currently set on the watcher. |
|
|
651 | |
|
|
652 | =item ev_cb_set (ev_TYPE *watcher, callback) |
|
|
653 | |
|
|
654 | Change the callback. You can change the callback at virtually any time |
|
|
655 | (modulo threads). |
|
|
656 | |
|
|
657 | =back |
|
|
658 | |
|
|
659 | |
374 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
660 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
375 | |
661 | |
376 | Each watcher has, by default, a member C<void *data> that you can change |
662 | 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 |
663 | 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 |
664 | 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 |
665 | 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 |
666 | member, you can also "subclass" the watcher type and provide your own |
381 | data: |
667 | data: |
382 | |
668 | |
… | |
… | |
404 | =head1 WATCHER TYPES |
690 | =head1 WATCHER TYPES |
405 | |
691 | |
406 | This section describes each watcher in detail, but will not repeat |
692 | This section describes each watcher in detail, but will not repeat |
407 | information given in the last section. |
693 | information given in the last section. |
408 | |
694 | |
|
|
695 | |
409 | =head2 C<ev_io> - is this file descriptor readable or writable |
696 | =head2 C<ev_io> - is this file descriptor readable or writable |
410 | |
697 | |
411 | I/O watchers check whether a file descriptor is readable or writable |
698 | I/O watchers check whether a file descriptor is readable or writable |
412 | in each iteration of the event loop (This behaviour is called |
699 | in each iteration of the event loop (This behaviour is called |
413 | level-triggering because you keep receiving events as long as the |
700 | level-triggering because you keep receiving events as long as the |
414 | condition persists. Remember you cna stop the watcher if you don't want to |
701 | condition persists. Remember you can stop the watcher if you don't want to |
415 | act on the event and neither want to receive future events). |
702 | act on the event and neither want to receive future events). |
416 | |
703 | |
417 | In general you can register as many read and/or write event watchers oer |
704 | 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 |
705 | 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 |
706 | descriptors to non-blocking mode is also usually a good idea (but not |
420 | required if you know what you are doing). |
707 | required if you know what you are doing). |
421 | |
708 | |
422 | You have to be careful with dup'ed file descriptors, though. Some backends |
709 | 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 |
710 | (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 |
711 | descriptors correctly if you register interest in two or more fds pointing |
425 | to the same file/socket etc. description. |
712 | to the same underlying file/socket etc. description (that is, they share |
|
|
713 | the same underlying "file open"). |
426 | |
714 | |
427 | If you must do this, then force the use of a known-to-be-good backend |
715 | 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 |
716 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
429 | EVMETHOD_POLL). |
717 | C<EVBACKEND_POLL>). |
430 | |
718 | |
431 | =over 4 |
719 | =over 4 |
432 | |
720 | |
433 | =item ev_io_init (ev_io *, callback, int fd, int events) |
721 | =item ev_io_init (ev_io *, callback, int fd, int events) |
434 | |
722 | |
… | |
… | |
436 | |
724 | |
437 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
725 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
438 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
726 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
439 | EV_WRITE> to receive the given events. |
727 | EV_WRITE> to receive the given events. |
440 | |
728 | |
|
|
729 | Please note that most of the more scalable backend mechanisms (for example |
|
|
730 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
731 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
732 | treat callback invocation as hint only), or retest separately with a safe |
|
|
733 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
734 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
|
|
735 | problem. Also note that it is quite easy to have your callback invoked |
|
|
736 | when the readyness condition is no longer valid even when employing |
|
|
737 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
738 | I/O unconditionally. |
|
|
739 | |
441 | =back |
740 | =back |
|
|
741 | |
|
|
742 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
|
|
743 | readable, but only once. Since it is likely line-buffered, you could |
|
|
744 | attempt to read a whole line in the callback: |
|
|
745 | |
|
|
746 | static void |
|
|
747 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
748 | { |
|
|
749 | ev_io_stop (loop, w); |
|
|
750 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
751 | } |
|
|
752 | |
|
|
753 | ... |
|
|
754 | struct ev_loop *loop = ev_default_init (0); |
|
|
755 | struct ev_io stdin_readable; |
|
|
756 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
757 | ev_io_start (loop, &stdin_readable); |
|
|
758 | ev_loop (loop, 0); |
|
|
759 | |
442 | |
760 | |
443 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
761 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
444 | |
762 | |
445 | Timer watchers are simple relative timers that generate an event after a |
763 | Timer watchers are simple relative timers that generate an event after a |
446 | given time, and optionally repeating in regular intervals after that. |
764 | given time, and optionally repeating in regular intervals after that. |
447 | |
765 | |
448 | The timers are based on real time, that is, if you register an event that |
766 | 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 |
767 | 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 |
768 | time, it will still time out after (roughly) and hour. "Roughly" because |
451 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
769 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
452 | monotonic clock option helps a lot here). |
770 | monotonic clock option helps a lot here). |
453 | |
771 | |
454 | The relative timeouts are calculated relative to the C<ev_now ()> |
772 | 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 |
773 | 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 |
774 | 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 |
775 | 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: |
776 | on the current time, use something like this to adjust for this: |
459 | |
777 | |
460 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
778 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
779 | |
|
|
780 | The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
781 | but if multiple timers become ready during the same loop iteration then |
|
|
782 | order of execution is undefined. |
461 | |
783 | |
462 | =over 4 |
784 | =over 4 |
463 | |
785 | |
464 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
786 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
465 | |
787 | |
… | |
… | |
471 | later, again, and again, until stopped manually. |
793 | later, again, and again, until stopped manually. |
472 | |
794 | |
473 | The timer itself will do a best-effort at avoiding drift, that is, if you |
795 | 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 |
796 | 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 |
797 | 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 |
798 | 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. |
799 | timer will not fire more than once per event loop iteration. |
478 | |
800 | |
479 | =item ev_timer_again (loop) |
801 | =item ev_timer_again (loop) |
480 | |
802 | |
481 | This will act as if the timer timed out and restart it again if it is |
803 | This will act as if the timer timed out and restart it again if it is |
… | |
… | |
495 | state where you do not expect data to travel on the socket, you can stop |
817 | state where you do not expect data to travel on the socket, you can stop |
496 | the timer, and again will automatically restart it if need be. |
818 | the timer, and again will automatically restart it if need be. |
497 | |
819 | |
498 | =back |
820 | =back |
499 | |
821 | |
|
|
822 | Example: create a timer that fires after 60 seconds. |
|
|
823 | |
|
|
824 | static void |
|
|
825 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
826 | { |
|
|
827 | .. one minute over, w is actually stopped right here |
|
|
828 | } |
|
|
829 | |
|
|
830 | struct ev_timer mytimer; |
|
|
831 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
832 | ev_timer_start (loop, &mytimer); |
|
|
833 | |
|
|
834 | Example: create a timeout timer that times out after 10 seconds of |
|
|
835 | inactivity. |
|
|
836 | |
|
|
837 | static void |
|
|
838 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
839 | { |
|
|
840 | .. ten seconds without any activity |
|
|
841 | } |
|
|
842 | |
|
|
843 | struct ev_timer mytimer; |
|
|
844 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
845 | ev_timer_again (&mytimer); /* start timer */ |
|
|
846 | ev_loop (loop, 0); |
|
|
847 | |
|
|
848 | // and in some piece of code that gets executed on any "activity": |
|
|
849 | // reset the timeout to start ticking again at 10 seconds |
|
|
850 | ev_timer_again (&mytimer); |
|
|
851 | |
|
|
852 | |
500 | =head2 C<ev_periodic> - to cron or not to cron it |
853 | =head2 C<ev_periodic> - to cron or not to cron |
501 | |
854 | |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
855 | Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex). |
856 | (and unfortunately a bit complex). |
504 | |
857 | |
505 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
858 | 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 |
859 | 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 |
860 | 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 () |
861 | 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 |
862 | + 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 |
863 | 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 |
864 | roughly 10 seconds later and of course not if you reset your system time |
512 | again). |
865 | again). |
513 | |
866 | |
514 | They can also be used to implement vastly more complex timers, such as |
867 | They can also be used to implement vastly more complex timers, such as |
515 | triggering an event on eahc midnight, local time. |
868 | triggering an event on eahc midnight, local time. |
516 | |
869 | |
|
|
870 | As with timers, the callback is guarenteed to be invoked only when the |
|
|
871 | time (C<at>) has been passed, but if multiple periodic timers become ready |
|
|
872 | during the same loop iteration then order of execution is undefined. |
|
|
873 | |
517 | =over 4 |
874 | =over 4 |
518 | |
875 | |
519 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
876 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
520 | |
877 | |
521 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
878 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
522 | |
879 | |
523 | Lots of arguments, lets sort it out... There are basically three modes of |
880 | Lots of arguments, lets sort it out... There are basically three modes of |
524 | operation, and we will explain them from simplest to complex: |
881 | operation, and we will explain them from simplest to complex: |
525 | |
|
|
526 | |
882 | |
527 | =over 4 |
883 | =over 4 |
528 | |
884 | |
529 | =item * absolute timer (interval = reschedule_cb = 0) |
885 | =item * absolute timer (interval = reschedule_cb = 0) |
530 | |
886 | |
… | |
… | |
558 | In this mode the values for C<interval> and C<at> are both being |
914 | 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 |
915 | ignored. Instead, each time the periodic watcher gets scheduled, the |
560 | reschedule callback will be called with the watcher as first, and the |
916 | reschedule callback will be called with the watcher as first, and the |
561 | current time as second argument. |
917 | current time as second argument. |
562 | |
918 | |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
919 | 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 |
920 | 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. |
921 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
566 | |
922 | 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 | |
923 | |
570 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
924 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
571 | ev_tstamp now)>, e.g.: |
925 | ev_tstamp now)>, e.g.: |
572 | |
926 | |
573 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
927 | 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 |
932 | 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 |
933 | (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 |
934 | will usually be called just before the callback will be triggered, but |
581 | might be called at other times, too. |
935 | might be called at other times, too. |
582 | |
936 | |
|
|
937 | NOTE: I<< This callback must always return a time that is later than the |
|
|
938 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
|
|
939 | |
583 | This can be used to create very complex timers, such as a timer that |
940 | 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 |
941 | 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 |
942 | next midnight after C<now> and return the timestamp value for this. How |
586 | is, again, up to you (but it is not trivial). |
943 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
944 | reason I omitted it as an example). |
587 | |
945 | |
588 | =back |
946 | =back |
589 | |
947 | |
590 | =item ev_periodic_again (loop, ev_periodic *) |
948 | =item ev_periodic_again (loop, ev_periodic *) |
591 | |
949 | |
… | |
… | |
594 | a different time than the last time it was called (e.g. in a crond like |
952 | a different time than the last time it was called (e.g. in a crond like |
595 | program when the crontabs have changed). |
953 | program when the crontabs have changed). |
596 | |
954 | |
597 | =back |
955 | =back |
598 | |
956 | |
|
|
957 | Example: call a callback every hour, or, more precisely, whenever the |
|
|
958 | system clock is divisible by 3600. The callback invocation times have |
|
|
959 | potentially a lot of jittering, but good long-term stability. |
|
|
960 | |
|
|
961 | static void |
|
|
962 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
963 | { |
|
|
964 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
965 | } |
|
|
966 | |
|
|
967 | struct ev_periodic hourly_tick; |
|
|
968 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
969 | ev_periodic_start (loop, &hourly_tick); |
|
|
970 | |
|
|
971 | Example: the same as above, but use a reschedule callback to do it: |
|
|
972 | |
|
|
973 | #include <math.h> |
|
|
974 | |
|
|
975 | static ev_tstamp |
|
|
976 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
977 | { |
|
|
978 | return fmod (now, 3600.) + 3600.; |
|
|
979 | } |
|
|
980 | |
|
|
981 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
982 | |
|
|
983 | Example: call a callback every hour, starting now: |
|
|
984 | |
|
|
985 | struct ev_periodic hourly_tick; |
|
|
986 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
987 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
988 | ev_periodic_start (loop, &hourly_tick); |
|
|
989 | |
|
|
990 | |
599 | =head2 C<ev_signal> - signal me when a signal gets signalled |
991 | =head2 C<ev_signal> - signal me when a signal gets signalled |
600 | |
992 | |
601 | Signal watchers will trigger an event when the process receives a specific |
993 | 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 |
994 | 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 |
995 | will try it's best to deliver signals synchronously, i.e. as part of the |
604 | normal event processing, like any other event. |
996 | normal event processing, like any other event. |
605 | |
997 | |
606 | You cna configure as many watchers as you like per signal. Only when the |
998 | 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 |
999 | 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 |
1000 | 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 |
1001 | 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 |
1002 | watcher for a signal is stopped libev will reset the signal handler to |
611 | SIG_DFL (regardless of what it was set to before). |
1003 | SIG_DFL (regardless of what it was set to before). |
… | |
… | |
619 | Configures the watcher to trigger on the given signal number (usually one |
1011 | Configures the watcher to trigger on the given signal number (usually one |
620 | of the C<SIGxxx> constants). |
1012 | of the C<SIGxxx> constants). |
621 | |
1013 | |
622 | =back |
1014 | =back |
623 | |
1015 | |
|
|
1016 | |
624 | =head2 C<ev_child> - wait for pid status changes |
1017 | =head2 C<ev_child> - wait for pid status changes |
625 | |
1018 | |
626 | Child watchers trigger when your process receives a SIGCHLD in response to |
1019 | 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). |
1020 | some child status changes (most typically when a child of yours dies). |
628 | |
1021 | |
… | |
… | |
633 | =item ev_child_set (ev_child *, int pid) |
1026 | =item ev_child_set (ev_child *, int pid) |
634 | |
1027 | |
635 | Configures the watcher to wait for status changes of process C<pid> (or |
1028 | 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 |
1029 | 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 |
1030 | 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 |
1031 | 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. |
1032 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
|
|
1033 | process causing the status change. |
640 | |
1034 | |
641 | =back |
1035 | =back |
|
|
1036 | |
|
|
1037 | Example: try to exit cleanly on SIGINT and SIGTERM. |
|
|
1038 | |
|
|
1039 | static void |
|
|
1040 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1041 | { |
|
|
1042 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1043 | } |
|
|
1044 | |
|
|
1045 | struct ev_signal signal_watcher; |
|
|
1046 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1047 | ev_signal_start (loop, &sigint_cb); |
|
|
1048 | |
642 | |
1049 | |
643 | =head2 C<ev_idle> - when you've got nothing better to do |
1050 | =head2 C<ev_idle> - when you've got nothing better to do |
644 | |
1051 | |
645 | Idle watchers trigger events when there are no other I/O or timer (or |
1052 | 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 |
1053 | (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 |
1054 | 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 |
1055 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
1056 | watchers are being called again and again, once per event loop iteration - |
649 | stopped, that is, or your process receives more events. |
1057 | until stopped, that is, or your process receives more events and becomes |
|
|
1058 | busy. |
650 | |
1059 | |
651 | The most noteworthy effect is that as long as any idle watchers are |
1060 | 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. |
1061 | active, the process will not block when waiting for new events. |
653 | |
1062 | |
654 | Apart from keeping your process non-blocking (which is a useful |
1063 | 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, |
1073 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
665 | believe me. |
1074 | believe me. |
666 | |
1075 | |
667 | =back |
1076 | =back |
668 | |
1077 | |
669 | =head2 prepare and check - your hooks into the event loop |
1078 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
|
|
1079 | callback, free it. Alos, use no error checking, as usual. |
670 | |
1080 | |
|
|
1081 | static void |
|
|
1082 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1083 | { |
|
|
1084 | free (w); |
|
|
1085 | // now do something you wanted to do when the program has |
|
|
1086 | // no longer asnything immediate to do. |
|
|
1087 | } |
|
|
1088 | |
|
|
1089 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1090 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1091 | ev_idle_start (loop, idle_cb); |
|
|
1092 | |
|
|
1093 | |
|
|
1094 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
|
|
1095 | |
671 | Prepare and check watchers usually (but not always) are used in |
1096 | Prepare and check watchers are usually (but not always) used in tandem: |
672 | tandom. Prepare watchers get invoked before the process blocks and check |
1097 | prepare watchers get invoked before the process blocks and check watchers |
673 | watchers afterwards. |
1098 | afterwards. |
674 | |
1099 | |
675 | Their main purpose is to integrate other event mechanisms into libev. This |
1100 | 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 |
1101 | 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. |
1102 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1103 | coroutine library and lots more. |
678 | |
1104 | |
679 | This is done by examining in each prepare call which file descriptors need |
1105 | 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 |
1106 | 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 |
1107 | 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 |
1108 | 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) |
1109 | any events that occured (by checking the pending status of all watchers |
684 | and call back into the library. |
1110 | and stopping them) and call back into the library. The I/O and timer |
|
|
1111 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
1112 | because you never know, you know?). |
685 | |
1113 | |
686 | As another example, the perl Coro module uses these hooks to integrate |
1114 | As another example, the Perl Coro module uses these hooks to integrate |
687 | coroutines into libev programs, by yielding to other active coroutines |
1115 | coroutines into libev programs, by yielding to other active coroutines |
688 | during each prepare and only letting the process block if no coroutines |
1116 | during each prepare and only letting the process block if no coroutines |
689 | are ready to run. |
1117 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
1118 | with priority higher than or equal to the event loop and one coroutine |
|
|
1119 | of lower priority, but only once, using idle watchers to keep the event |
|
|
1120 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
1121 | low-priority coroutines to idle/background tasks). |
690 | |
1122 | |
691 | =over 4 |
1123 | =over 4 |
692 | |
1124 | |
693 | =item ev_prepare_init (ev_prepare *, callback) |
1125 | =item ev_prepare_init (ev_prepare *, callback) |
694 | |
1126 | |
695 | =item ev_check_init (ev_check *, callback) |
1127 | =item ev_check_init (ev_check *, callback) |
696 | |
1128 | |
697 | Initialises and configures the prepare or check watcher - they have no |
1129 | 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> |
1130 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
699 | macros, but using them is utterly, utterly pointless. |
1131 | macros, but using them is utterly, utterly and completely pointless. |
700 | |
1132 | |
701 | =back |
1133 | =back |
|
|
1134 | |
|
|
1135 | Example: *TODO*. |
|
|
1136 | |
|
|
1137 | |
|
|
1138 | =head2 C<ev_embed> - when one backend isn't enough |
|
|
1139 | |
|
|
1140 | This is a rather advanced watcher type that lets you embed one event loop |
|
|
1141 | into another (currently only C<ev_io> events are supported in the embedded |
|
|
1142 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1143 | fashion and must not be used). |
|
|
1144 | |
|
|
1145 | There are primarily two reasons you would want that: work around bugs and |
|
|
1146 | prioritise I/O. |
|
|
1147 | |
|
|
1148 | As an example for a bug workaround, the kqueue backend might only support |
|
|
1149 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1150 | still want to make use of it because you have many sockets and it scales |
|
|
1151 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1152 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1153 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1154 | at least you can use both at what they are best. |
|
|
1155 | |
|
|
1156 | As for prioritising I/O: rarely you have the case where some fds have |
|
|
1157 | to be watched and handled very quickly (with low latency), and even |
|
|
1158 | priorities and idle watchers might have too much overhead. In this case |
|
|
1159 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1160 | a second one, and embed the second one in the first. |
|
|
1161 | |
|
|
1162 | As long as the watcher is active, the callback will be invoked every time |
|
|
1163 | there might be events pending in the embedded loop. The callback must then |
|
|
1164 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
|
|
1165 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1166 | loop strictly lower priority for example). You can also set the callback |
|
|
1167 | to C<0>, in which case the embed watcher will automatically execute the |
|
|
1168 | embedded loop sweep. |
|
|
1169 | |
|
|
1170 | As long as the watcher is started it will automatically handle events. The |
|
|
1171 | callback will be invoked whenever some events have been handled. You can |
|
|
1172 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
1173 | interested in that. |
|
|
1174 | |
|
|
1175 | Also, there have not currently been made special provisions for forking: |
|
|
1176 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
|
|
1177 | but you will also have to stop and restart any C<ev_embed> watchers |
|
|
1178 | yourself. |
|
|
1179 | |
|
|
1180 | Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1181 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
|
|
1182 | portable one. |
|
|
1183 | |
|
|
1184 | So when you want to use this feature you will always have to be prepared |
|
|
1185 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1186 | this is to have a separate variables for your embeddable loop, try to |
|
|
1187 | create it, and if that fails, use the normal loop for everything: |
|
|
1188 | |
|
|
1189 | struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1190 | struct ev_loop *loop_lo = 0; |
|
|
1191 | struct ev_embed embed; |
|
|
1192 | |
|
|
1193 | // see if there is a chance of getting one that works |
|
|
1194 | // (remember that a flags value of 0 means autodetection) |
|
|
1195 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1196 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1197 | : 0; |
|
|
1198 | |
|
|
1199 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
1200 | if (loop_lo) |
|
|
1201 | { |
|
|
1202 | ev_embed_init (&embed, 0, loop_lo); |
|
|
1203 | ev_embed_start (loop_hi, &embed); |
|
|
1204 | } |
|
|
1205 | else |
|
|
1206 | loop_lo = loop_hi; |
|
|
1207 | |
|
|
1208 | =over 4 |
|
|
1209 | |
|
|
1210 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1211 | |
|
|
1212 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1213 | |
|
|
1214 | Configures the watcher to embed the given loop, which must be |
|
|
1215 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1216 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1217 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1218 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1219 | |
|
|
1220 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1221 | |
|
|
1222 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1223 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1224 | apropriate way for embedded loops. |
|
|
1225 | |
|
|
1226 | =back |
|
|
1227 | |
702 | |
1228 | |
703 | =head1 OTHER FUNCTIONS |
1229 | =head1 OTHER FUNCTIONS |
704 | |
1230 | |
705 | There are some other fucntions of possible interest. Described. Here. Now. |
1231 | There are some other functions of possible interest. Described. Here. Now. |
706 | |
1232 | |
707 | =over 4 |
1233 | =over 4 |
708 | |
1234 | |
709 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
1235 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
710 | |
1236 | |
711 | This function combines a simple timer and an I/O watcher, calls your |
1237 | This function combines a simple timer and an I/O watcher, calls your |
712 | callback on whichever event happens first and automatically stop both |
1238 | 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 |
1239 | 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 |
1240 | or timeout without having to allocate/configure/start/stop/free one or |
715 | more watchers yourself. |
1241 | more watchers yourself. |
716 | |
1242 | |
717 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
1243 | 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 |
1244 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
719 | will be craeted and started. |
1245 | C<events> set will be craeted and started. |
720 | |
1246 | |
721 | If C<timeout> is less than 0, then no timeout watcher will be |
1247 | 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 |
1248 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
723 | = 0) will be started. |
1249 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
|
|
1250 | dubious value. |
724 | |
1251 | |
725 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
1252 | 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>, |
1253 | 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>: |
1254 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
|
|
1255 | value passed to C<ev_once>: |
728 | |
1256 | |
729 | static void stdin_ready (int revents, void *arg) |
1257 | static void stdin_ready (int revents, void *arg) |
730 | { |
1258 | { |
731 | if (revents & EV_TIMEOUT) |
1259 | if (revents & EV_TIMEOUT) |
732 | /* doh, nothing entered */ |
1260 | /* doh, nothing entered */; |
733 | else if (revents & EV_READ) |
1261 | else if (revents & EV_READ) |
734 | /* stdin might have data for us, joy! */ |
1262 | /* stdin might have data for us, joy! */; |
735 | } |
1263 | } |
736 | |
1264 | |
737 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
1265 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
738 | |
1266 | |
739 | =item ev_feed_event (loop, watcher, int events) |
1267 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
740 | |
1268 | |
741 | Feeds the given event set into the event loop, as if the specified event |
1269 | 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 |
1270 | had happened for the specified watcher (which must be a pointer to an |
743 | initialised but not necessarily active event watcher). |
1271 | initialised but not necessarily started event watcher). |
744 | |
1272 | |
745 | =item ev_feed_fd_event (loop, int fd, int revents) |
1273 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
746 | |
1274 | |
747 | Feed an event on the given fd, as if a file descriptor backend detected it. |
1275 | Feed an event on the given fd, as if a file descriptor backend detected |
|
|
1276 | the given events it. |
748 | |
1277 | |
749 | =item ev_feed_signal_event (loop, int signum) |
1278 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
750 | |
1279 | |
751 | Feed an event as if the given signal occured (loop must be the default loop!). |
1280 | Feed an event as if the given signal occured (C<loop> must be the default |
|
|
1281 | loop!). |
752 | |
1282 | |
753 | =back |
1283 | =back |
|
|
1284 | |
|
|
1285 | |
|
|
1286 | =head1 LIBEVENT EMULATION |
|
|
1287 | |
|
|
1288 | Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
1289 | emulate the internals of libevent, so here are some usage hints: |
|
|
1290 | |
|
|
1291 | =over 4 |
|
|
1292 | |
|
|
1293 | =item * Use it by including <event.h>, as usual. |
|
|
1294 | |
|
|
1295 | =item * The following members are fully supported: ev_base, ev_callback, |
|
|
1296 | ev_arg, ev_fd, ev_res, ev_events. |
|
|
1297 | |
|
|
1298 | =item * Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
1299 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
1300 | it a private API). |
|
|
1301 | |
|
|
1302 | =item * Priorities are not currently supported. Initialising priorities |
|
|
1303 | will fail and all watchers will have the same priority, even though there |
|
|
1304 | is an ev_pri field. |
|
|
1305 | |
|
|
1306 | =item * Other members are not supported. |
|
|
1307 | |
|
|
1308 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
|
|
1309 | to use the libev header file and library. |
|
|
1310 | |
|
|
1311 | =back |
|
|
1312 | |
|
|
1313 | =head1 C++ SUPPORT |
|
|
1314 | |
|
|
1315 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1316 | you to use some convinience methods to start/stop watchers and also change |
|
|
1317 | the callback model to a model using method callbacks on objects. |
|
|
1318 | |
|
|
1319 | To use it, |
|
|
1320 | |
|
|
1321 | #include <ev++.h> |
|
|
1322 | |
|
|
1323 | (it is not installed by default). This automatically includes F<ev.h> |
|
|
1324 | and puts all of its definitions (many of them macros) into the global |
|
|
1325 | namespace. All C++ specific things are put into the C<ev> namespace. |
|
|
1326 | |
|
|
1327 | It should support all the same embedding options as F<ev.h>, most notably |
|
|
1328 | C<EV_MULTIPLICITY>. |
|
|
1329 | |
|
|
1330 | Here is a list of things available in the C<ev> namespace: |
|
|
1331 | |
|
|
1332 | =over 4 |
|
|
1333 | |
|
|
1334 | =item C<ev::READ>, C<ev::WRITE> etc. |
|
|
1335 | |
|
|
1336 | These are just enum values with the same values as the C<EV_READ> etc. |
|
|
1337 | macros from F<ev.h>. |
|
|
1338 | |
|
|
1339 | =item C<ev::tstamp>, C<ev::now> |
|
|
1340 | |
|
|
1341 | Aliases to the same types/functions as with the C<ev_> prefix. |
|
|
1342 | |
|
|
1343 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
|
|
1344 | |
|
|
1345 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
|
|
1346 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
|
|
1347 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
|
|
1348 | defines by many implementations. |
|
|
1349 | |
|
|
1350 | All of those classes have these methods: |
|
|
1351 | |
|
|
1352 | =over 4 |
|
|
1353 | |
|
|
1354 | =item ev::TYPE::TYPE (object *, object::method *) |
|
|
1355 | |
|
|
1356 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
|
|
1357 | |
|
|
1358 | =item ev::TYPE::~TYPE |
|
|
1359 | |
|
|
1360 | The constructor takes a pointer to an object and a method pointer to |
|
|
1361 | the event handler callback to call in this class. The constructor calls |
|
|
1362 | C<ev_init> for you, which means you have to call the C<set> method |
|
|
1363 | before starting it. If you do not specify a loop then the constructor |
|
|
1364 | automatically associates the default loop with this watcher. |
|
|
1365 | |
|
|
1366 | The destructor automatically stops the watcher if it is active. |
|
|
1367 | |
|
|
1368 | =item w->set (struct ev_loop *) |
|
|
1369 | |
|
|
1370 | Associates a different C<struct ev_loop> with this watcher. You can only |
|
|
1371 | do this when the watcher is inactive (and not pending either). |
|
|
1372 | |
|
|
1373 | =item w->set ([args]) |
|
|
1374 | |
|
|
1375 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
|
|
1376 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1377 | automatically stopped and restarted. |
|
|
1378 | |
|
|
1379 | =item w->start () |
|
|
1380 | |
|
|
1381 | Starts the watcher. Note that there is no C<loop> argument as the |
|
|
1382 | constructor already takes the loop. |
|
|
1383 | |
|
|
1384 | =item w->stop () |
|
|
1385 | |
|
|
1386 | Stops the watcher if it is active. Again, no C<loop> argument. |
|
|
1387 | |
|
|
1388 | =item w->again () C<ev::timer>, C<ev::periodic> only |
|
|
1389 | |
|
|
1390 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
|
|
1391 | C<ev_TYPE_again> function. |
|
|
1392 | |
|
|
1393 | =item w->sweep () C<ev::embed> only |
|
|
1394 | |
|
|
1395 | Invokes C<ev_embed_sweep>. |
|
|
1396 | |
|
|
1397 | =back |
|
|
1398 | |
|
|
1399 | =back |
|
|
1400 | |
|
|
1401 | Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1402 | the constructor. |
|
|
1403 | |
|
|
1404 | class myclass |
|
|
1405 | { |
|
|
1406 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1407 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1408 | |
|
|
1409 | myclass (); |
|
|
1410 | } |
|
|
1411 | |
|
|
1412 | myclass::myclass (int fd) |
|
|
1413 | : io (this, &myclass::io_cb), |
|
|
1414 | idle (this, &myclass::idle_cb) |
|
|
1415 | { |
|
|
1416 | io.start (fd, ev::READ); |
|
|
1417 | } |
|
|
1418 | |
|
|
1419 | =head1 EMBEDDING |
|
|
1420 | |
|
|
1421 | Libev can (and often is) directly embedded into host |
|
|
1422 | applications. Examples of applications that embed it include the Deliantra |
|
|
1423 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1424 | and rxvt-unicode. |
|
|
1425 | |
|
|
1426 | The goal is to enable you to just copy the neecssary files into your |
|
|
1427 | source directory without having to change even a single line in them, so |
|
|
1428 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1429 | libev somewhere in your source tree). |
|
|
1430 | |
|
|
1431 | =head2 FILESETS |
|
|
1432 | |
|
|
1433 | Depending on what features you need you need to include one or more sets of files |
|
|
1434 | in your app. |
|
|
1435 | |
|
|
1436 | =head3 CORE EVENT LOOP |
|
|
1437 | |
|
|
1438 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
1439 | configuration (no autoconf): |
|
|
1440 | |
|
|
1441 | #define EV_STANDALONE 1 |
|
|
1442 | #include "ev.c" |
|
|
1443 | |
|
|
1444 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
1445 | single C source file only to provide the function implementations. To use |
|
|
1446 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
1447 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
1448 | where you can put other configuration options): |
|
|
1449 | |
|
|
1450 | #define EV_STANDALONE 1 |
|
|
1451 | #include "ev.h" |
|
|
1452 | |
|
|
1453 | Both header files and implementation files can be compiled with a C++ |
|
|
1454 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1455 | as a bug). |
|
|
1456 | |
|
|
1457 | You need the following files in your source tree, or in a directory |
|
|
1458 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
1459 | |
|
|
1460 | ev.h |
|
|
1461 | ev.c |
|
|
1462 | ev_vars.h |
|
|
1463 | ev_wrap.h |
|
|
1464 | |
|
|
1465 | ev_win32.c required on win32 platforms only |
|
|
1466 | |
|
|
1467 | ev_select.c only when select backend is enabled (which is is by default) |
|
|
1468 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1469 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1470 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1471 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1472 | |
|
|
1473 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
1474 | to compile a single file. |
|
|
1475 | |
|
|
1476 | =head3 LIBEVENT COMPATIBILITY API |
|
|
1477 | |
|
|
1478 | To include the libevent compatibility API, also include: |
|
|
1479 | |
|
|
1480 | #include "event.c" |
|
|
1481 | |
|
|
1482 | in the file including F<ev.c>, and: |
|
|
1483 | |
|
|
1484 | #include "event.h" |
|
|
1485 | |
|
|
1486 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
1487 | |
|
|
1488 | You need the following additional files for this: |
|
|
1489 | |
|
|
1490 | event.h |
|
|
1491 | event.c |
|
|
1492 | |
|
|
1493 | =head3 AUTOCONF SUPPORT |
|
|
1494 | |
|
|
1495 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
1496 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
1497 | F<configure.ac> and leave C<EV_STANDALONE> off. F<ev.c> will then include |
|
|
1498 | F<config.h> and configure itself accordingly. |
|
|
1499 | |
|
|
1500 | For this of course you need the m4 file: |
|
|
1501 | |
|
|
1502 | libev.m4 |
|
|
1503 | |
|
|
1504 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
1505 | |
|
|
1506 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1507 | before including any of its files. The default is not to build for multiplicity |
|
|
1508 | and only include the select backend. |
|
|
1509 | |
|
|
1510 | =over 4 |
|
|
1511 | |
|
|
1512 | =item EV_STANDALONE |
|
|
1513 | |
|
|
1514 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
1515 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
1516 | implementations for some libevent functions (such as logging, which is not |
|
|
1517 | supported). It will also not define any of the structs usually found in |
|
|
1518 | F<event.h> that are not directly supported by the libev core alone. |
|
|
1519 | |
|
|
1520 | =item EV_USE_MONOTONIC |
|
|
1521 | |
|
|
1522 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1523 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1524 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1525 | usually have to link against librt or something similar. Enabling it when |
|
|
1526 | the functionality isn't available is safe, though, althoguh you have |
|
|
1527 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
1528 | function is hiding in (often F<-lrt>). |
|
|
1529 | |
|
|
1530 | =item EV_USE_REALTIME |
|
|
1531 | |
|
|
1532 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1533 | realtime clock option at compiletime (and assume its availability at |
|
|
1534 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1535 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
1536 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
|
|
1537 | in the description of C<EV_USE_MONOTONIC>, though. |
|
|
1538 | |
|
|
1539 | =item EV_USE_SELECT |
|
|
1540 | |
|
|
1541 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
1542 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
1543 | other method takes over, select will be it. Otherwise the select backend |
|
|
1544 | will not be compiled in. |
|
|
1545 | |
|
|
1546 | =item EV_SELECT_USE_FD_SET |
|
|
1547 | |
|
|
1548 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
1549 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1550 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
1551 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1552 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1553 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
1554 | influence the size of the C<fd_set> used. |
|
|
1555 | |
|
|
1556 | =item EV_SELECT_IS_WINSOCKET |
|
|
1557 | |
|
|
1558 | When defined to C<1>, the select backend will assume that |
|
|
1559 | select/socket/connect etc. don't understand file descriptors but |
|
|
1560 | wants osf handles on win32 (this is the case when the select to |
|
|
1561 | be used is the winsock select). This means that it will call |
|
|
1562 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
1563 | it is assumed that all these functions actually work on fds, even |
|
|
1564 | on win32. Should not be defined on non-win32 platforms. |
|
|
1565 | |
|
|
1566 | =item EV_USE_POLL |
|
|
1567 | |
|
|
1568 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
1569 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1570 | takes precedence over select. |
|
|
1571 | |
|
|
1572 | =item EV_USE_EPOLL |
|
|
1573 | |
|
|
1574 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
1575 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
1576 | otherwise another method will be used as fallback. This is the |
|
|
1577 | preferred backend for GNU/Linux systems. |
|
|
1578 | |
|
|
1579 | =item EV_USE_KQUEUE |
|
|
1580 | |
|
|
1581 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
1582 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
1583 | otherwise another method will be used as fallback. This is the preferred |
|
|
1584 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
1585 | supports some types of fds correctly (the only platform we found that |
|
|
1586 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
1587 | not be used unless explicitly requested. The best way to use it is to find |
|
|
1588 | out wether kqueue supports your type of fd properly and use an embedded |
|
|
1589 | kqueue loop. |
|
|
1590 | |
|
|
1591 | =item EV_USE_PORT |
|
|
1592 | |
|
|
1593 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
1594 | 10 port style backend. Its availability will be detected at runtime, |
|
|
1595 | otherwise another method will be used as fallback. This is the preferred |
|
|
1596 | backend for Solaris 10 systems. |
|
|
1597 | |
|
|
1598 | =item EV_USE_DEVPOLL |
|
|
1599 | |
|
|
1600 | reserved for future expansion, works like the USE symbols above. |
|
|
1601 | |
|
|
1602 | =item EV_H |
|
|
1603 | |
|
|
1604 | The name of the F<ev.h> header file used to include it. The default if |
|
|
1605 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
|
|
1606 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
1607 | |
|
|
1608 | =item EV_CONFIG_H |
|
|
1609 | |
|
|
1610 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
1611 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
1612 | C<EV_H>, above. |
|
|
1613 | |
|
|
1614 | =item EV_EVENT_H |
|
|
1615 | |
|
|
1616 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
1617 | of how the F<event.h> header can be found. |
|
|
1618 | |
|
|
1619 | =item EV_PROTOTYPES |
|
|
1620 | |
|
|
1621 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
1622 | prototypes, but still define all the structs and other symbols. This is |
|
|
1623 | occasionally useful if you want to provide your own wrapper functions |
|
|
1624 | around libev functions. |
|
|
1625 | |
|
|
1626 | =item EV_MULTIPLICITY |
|
|
1627 | |
|
|
1628 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
1629 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
1630 | additional independent event loops. Otherwise there will be no support |
|
|
1631 | for multiple event loops and there is no first event loop pointer |
|
|
1632 | argument. Instead, all functions act on the single default loop. |
|
|
1633 | |
|
|
1634 | =item EV_PERIODICS |
|
|
1635 | |
|
|
1636 | If undefined or defined to be C<1>, then periodic timers are supported, |
|
|
1637 | otherwise not. This saves a few kb of code. |
|
|
1638 | |
|
|
1639 | =item EV_COMMON |
|
|
1640 | |
|
|
1641 | By default, all watchers have a C<void *data> member. By redefining |
|
|
1642 | this macro to a something else you can include more and other types of |
|
|
1643 | members. You have to define it each time you include one of the files, |
|
|
1644 | though, and it must be identical each time. |
|
|
1645 | |
|
|
1646 | For example, the perl EV module uses something like this: |
|
|
1647 | |
|
|
1648 | #define EV_COMMON \ |
|
|
1649 | SV *self; /* contains this struct */ \ |
|
|
1650 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
1651 | |
|
|
1652 | =item EV_CB_DECLARE(type) |
|
|
1653 | |
|
|
1654 | =item EV_CB_INVOKE(watcher,revents) |
|
|
1655 | |
|
|
1656 | =item ev_set_cb(ev,cb) |
|
|
1657 | |
|
|
1658 | Can be used to change the callback member declaration in each watcher, |
|
|
1659 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
1660 | definition and a statement, respectively. See the F<ev.v> header file for |
|
|
1661 | their default definitions. One possible use for overriding these is to |
|
|
1662 | avoid the ev_loop pointer as first argument in all cases, or to use method |
|
|
1663 | calls instead of plain function calls in C++. |
|
|
1664 | |
|
|
1665 | =head2 EXAMPLES |
|
|
1666 | |
|
|
1667 | For a real-world example of a program the includes libev |
|
|
1668 | verbatim, you can have a look at the EV perl module |
|
|
1669 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
1670 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
1671 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
1672 | will be compiled. It is pretty complex because it provides its own header |
|
|
1673 | file. |
|
|
1674 | |
|
|
1675 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
1676 | that everybody includes and which overrides some autoconf choices: |
|
|
1677 | |
|
|
1678 | #define EV_USE_POLL 0 |
|
|
1679 | #define EV_MULTIPLICITY 0 |
|
|
1680 | #define EV_PERIODICS 0 |
|
|
1681 | #define EV_CONFIG_H <config.h> |
|
|
1682 | |
|
|
1683 | #include "ev++.h" |
|
|
1684 | |
|
|
1685 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
1686 | |
|
|
1687 | #include "ev_cpp.h" |
|
|
1688 | #include "ev.c" |
754 | |
1689 | |
755 | =head1 AUTHOR |
1690 | =head1 AUTHOR |
756 | |
1691 | |
757 | Marc Lehmann <libev@schmorp.de>. |
1692 | Marc Lehmann <libev@schmorp.de>. |
758 | |
1693 | |