1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - the DBI of event loop programming |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
4 | EV, Event, Glib, Tk, UV, Perl, Event::Lib, Irssi, rxvt-unicode, |
5 | event loops. |
5 | IO::Async, Qt, FLTK and POE are various supported event |
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6 | loops/environments. |
6 | |
7 | |
7 | SYNOPSIS |
8 | SYNOPSIS |
8 | use AnyEvent; |
9 | use AnyEvent; |
9 | |
10 | |
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11 | # if you prefer function calls, look at the AE manpage for |
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12 | # an alternative API. |
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13 | |
10 | # file descriptor readable |
14 | # file handle or descriptor readable |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
15 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
12 | |
16 | |
13 | # one-shot or repeating timers |
17 | # one-shot or repeating timers |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
18 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
19 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...); |
16 | |
20 | |
17 | print AnyEvent->now; # prints current event loop time |
21 | print AnyEvent->now; # prints current event loop time |
18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
22 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
19 | |
23 | |
20 | # POSIX signal |
24 | # POSIX signal |
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37 | |
41 | |
38 | INTRODUCTION/TUTORIAL |
42 | INTRODUCTION/TUTORIAL |
39 | This manpage is mainly a reference manual. If you are interested in a |
43 | This manpage is mainly a reference manual. If you are interested in a |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
44 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
41 | manpage. |
45 | manpage. |
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46 | |
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47 | SUPPORT |
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48 | An FAQ document is available as AnyEvent::FAQ. |
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49 | |
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50 | There also is a mailinglist for discussing all things AnyEvent, and an |
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51 | IRC channel, too. |
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52 | |
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53 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
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54 | Repository, at <http://anyevent.schmorp.de>, for more info. |
42 | |
55 | |
43 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
56 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
44 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
57 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
45 | nowadays. So what is different about AnyEvent? |
58 | nowadays. So what is different about AnyEvent? |
46 | |
59 | |
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61 | module users into the same thing by forcing them to use the same event |
74 | module users into the same thing by forcing them to use the same event |
62 | model you use. |
75 | model you use. |
63 | |
76 | |
64 | For modules like POE or IO::Async (which is a total misnomer as it is |
77 | For modules like POE or IO::Async (which is a total misnomer as it is |
65 | actually doing all I/O *synchronously*...), using them in your module is |
78 | actually doing all I/O *synchronously*...), using them in your module is |
66 | like joining a cult: After you joined, you are dependent on them and you |
79 | like joining a cult: After you join, you are dependent on them and you |
67 | cannot use anything else, as they are simply incompatible to everything |
80 | cannot use anything else, as they are simply incompatible to everything |
68 | that isn't them. What's worse, all the potential users of your module |
81 | that isn't them. What's worse, all the potential users of your module |
69 | are *also* forced to use the same event loop you use. |
82 | are *also* forced to use the same event loop you use. |
70 | |
83 | |
71 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
84 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
72 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
85 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
73 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your |
86 | with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module |
74 | module uses one of those, every user of your module has to use it, too. |
87 | uses one of those, every user of your module has to use it, too. But if |
75 | But if your module uses AnyEvent, it works transparently with all event |
88 | your module uses AnyEvent, it works transparently with all event models |
76 | models it supports (including stuff like IO::Async, as long as those use |
89 | it supports (including stuff like IO::Async, as long as those use one of |
77 | one of the supported event loops. It is trivial to add new event loops |
90 | the supported event loops. It is easy to add new event loops to |
78 | to AnyEvent, too, so it is future-proof). |
91 | AnyEvent, too, so it is future-proof). |
79 | |
92 | |
80 | In addition to being free of having to use *the one and only true event |
93 | In addition to being free of having to use *the one and only true event |
81 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
94 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
82 | modules, you get an enormous amount of code and strict rules you have to |
95 | modules, you get an enormous amount of code and strict rules you have to |
83 | follow. AnyEvent, on the other hand, is lean and up to the point, by |
96 | follow. AnyEvent, on the other hand, is lean and to the point, by only |
84 | only offering the functionality that is necessary, in as thin as a |
97 | offering the functionality that is necessary, in as thin as a wrapper as |
85 | wrapper as technically possible. |
98 | technically possible. |
86 | |
99 | |
87 | Of course, AnyEvent comes with a big (and fully optional!) toolbox of |
100 | Of course, AnyEvent comes with a big (and fully optional!) toolbox of |
88 | useful functionality, such as an asynchronous DNS resolver, 100% |
101 | useful functionality, such as an asynchronous DNS resolver, 100% |
89 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
102 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
90 | such as Windows) and lots of real-world knowledge and workarounds for |
103 | such as Windows) and lots of real-world knowledge and workarounds for |
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93 | Now, if you *do want* lots of policy (this can arguably be somewhat |
106 | Now, if you *do want* lots of policy (this can arguably be somewhat |
94 | useful) and you want to force your users to use the one and only event |
107 | useful) and you want to force your users to use the one and only event |
95 | model, you should *not* use this module. |
108 | model, you should *not* use this module. |
96 | |
109 | |
97 | DESCRIPTION |
110 | DESCRIPTION |
98 | AnyEvent provides an identical interface to multiple event loops. This |
111 | AnyEvent provides a uniform interface to various event loops. This |
99 | allows module authors to utilise an event loop without forcing module |
112 | allows module authors to use event loop functionality without forcing |
100 | users to use the same event loop (as only a single event loop can |
113 | module users to use a specific event loop implementation (since more |
101 | coexist peacefully at any one time). |
114 | than one event loop cannot coexist peacefully). |
102 | |
115 | |
103 | The interface itself is vaguely similar, but not identical to the Event |
116 | The interface itself is vaguely similar, but not identical to the Event |
104 | module. |
117 | module. |
105 | |
118 | |
106 | During the first call of any watcher-creation method, the module tries |
119 | During the first call of any watcher-creation method, the module tries |
107 | to detect the currently loaded event loop by probing whether one of the |
120 | to detect the currently loaded event loop by probing whether one of the |
108 | following modules is already loaded: EV, Event, Glib, |
121 | following modules is already loaded: EV, AnyEvent::Loop, Event, Glib, |
109 | AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found is |
122 | Tk, Event::Lib, Qt, POE. The first one found is used. If none are |
110 | used. If none are found, the module tries to load these modules |
123 | detected, the module tries to load the first four modules in the order |
111 | (excluding Tk, Event::Lib, Qt and POE as the pure perl adaptor should |
124 | given; but note that if EV is not available, the pure-perl |
112 | always succeed) in the order given. The first one that can be |
125 | AnyEvent::Loop should always work, so the other two are not normally |
113 | successfully loaded will be used. If, after this, still none could be |
126 | tried. |
114 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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115 | very efficient, but should work everywhere. |
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116 | |
127 | |
117 | Because AnyEvent first checks for modules that are already loaded, |
128 | Because AnyEvent first checks for modules that are already loaded, |
118 | loading an event model explicitly before first using AnyEvent will |
129 | loading an event model explicitly before first using AnyEvent will |
119 | likely make that model the default. For example: |
130 | likely make that model the default. For example: |
120 | |
131 | |
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122 | use AnyEvent; |
133 | use AnyEvent; |
123 | |
134 | |
124 | # .. AnyEvent will likely default to Tk |
135 | # .. AnyEvent will likely default to Tk |
125 | |
136 | |
126 | The *likely* means that, if any module loads another event model and |
137 | The *likely* means that, if any module loads another event model and |
127 | starts using it, all bets are off. Maybe you should tell their authors |
138 | starts using it, all bets are off - this case should be very rare |
128 | to use AnyEvent so their modules work together with others seamlessly... |
139 | though, as very few modules hardcode event loops without announcing this |
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140 | very loudly. |
129 | |
141 | |
130 | The pure-perl implementation of AnyEvent is called |
142 | The pure-perl implementation of AnyEvent is called "AnyEvent::Loop". |
131 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
143 | Like other event modules you can load it explicitly and enjoy the high |
132 | explicitly and enjoy the high availability of that event loop :) |
144 | availability of that event loop :) |
133 | |
145 | |
134 | WATCHERS |
146 | WATCHERS |
135 | AnyEvent has the central concept of a *watcher*, which is an object that |
147 | AnyEvent has the central concept of a *watcher*, which is an object that |
136 | stores relevant data for each kind of event you are waiting for, such as |
148 | stores relevant data for each kind of event you are waiting for, such as |
137 | the callback to call, the file handle to watch, etc. |
149 | the callback to call, the file handle to watch, etc. |
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141 | callback when the event occurs (of course, only when the event model is |
153 | callback when the event occurs (of course, only when the event model is |
142 | in control). |
154 | in control). |
143 | |
155 | |
144 | Note that callbacks must not permanently change global variables |
156 | Note that callbacks must not permanently change global variables |
145 | potentially in use by the event loop (such as $_ or $[) and that |
157 | potentially in use by the event loop (such as $_ or $[) and that |
146 | callbacks must not "die". The former is good programming practise in |
158 | callbacks must not "die". The former is good programming practice in |
147 | Perl and the latter stems from the fact that exception handling differs |
159 | Perl and the latter stems from the fact that exception handling differs |
148 | widely between event loops. |
160 | widely between event loops. |
149 | |
161 | |
150 | To disable the watcher you have to destroy it (e.g. by setting the |
162 | To disable a watcher you have to destroy it (e.g. by setting the |
151 | variable you store it in to "undef" or otherwise deleting all references |
163 | variable you store it in to "undef" or otherwise deleting all references |
152 | to it). |
164 | to it). |
153 | |
165 | |
154 | All watchers are created by calling a method on the "AnyEvent" class. |
166 | All watchers are created by calling a method on the "AnyEvent" class. |
155 | |
167 | |
156 | Many watchers either are used with "recursion" (repeating timers for |
168 | Many watchers either are used with "recursion" (repeating timers for |
157 | example), or need to refer to their watcher object in other ways. |
169 | example), or need to refer to their watcher object in other ways. |
158 | |
170 | |
159 | An any way to achieve that is this pattern: |
171 | One way to achieve that is this pattern: |
160 | |
172 | |
161 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
173 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
162 | # you can use $w here, for example to undef it |
174 | # you can use $w here, for example to undef it |
163 | undef $w; |
175 | undef $w; |
164 | }); |
176 | }); |
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166 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
178 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
167 | my variables are only visible after the statement in which they are |
179 | my variables are only visible after the statement in which they are |
168 | declared. |
180 | declared. |
169 | |
181 | |
170 | I/O WATCHERS |
182 | I/O WATCHERS |
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183 | $w = AnyEvent->io ( |
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184 | fh => <filehandle_or_fileno>, |
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185 | poll => <"r" or "w">, |
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186 | cb => <callback>, |
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187 | ); |
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188 | |
171 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
189 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
172 | the following mandatory key-value pairs as arguments: |
190 | the following mandatory key-value pairs as arguments: |
173 | |
191 | |
174 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
192 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
175 | events (AnyEvent might or might not keep a reference to this file |
193 | events (AnyEvent might or might not keep a reference to this file |
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189 | |
207 | |
190 | The I/O watcher might use the underlying file descriptor or a copy of |
208 | The I/O watcher might use the underlying file descriptor or a copy of |
191 | it. You must not close a file handle as long as any watcher is active on |
209 | it. You must not close a file handle as long as any watcher is active on |
192 | the underlying file descriptor. |
210 | the underlying file descriptor. |
193 | |
211 | |
194 | Some event loops issue spurious readyness notifications, so you should |
212 | Some event loops issue spurious readiness notifications, so you should |
195 | always use non-blocking calls when reading/writing from/to your file |
213 | always use non-blocking calls when reading/writing from/to your file |
196 | handles. |
214 | handles. |
197 | |
215 | |
198 | Example: wait for readability of STDIN, then read a line and disable the |
216 | Example: wait for readability of STDIN, then read a line and disable the |
199 | watcher. |
217 | watcher. |
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203 | warn "read: $input\n"; |
221 | warn "read: $input\n"; |
204 | undef $w; |
222 | undef $w; |
205 | }); |
223 | }); |
206 | |
224 | |
207 | TIME WATCHERS |
225 | TIME WATCHERS |
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226 | $w = AnyEvent->timer (after => <seconds>, cb => <callback>); |
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227 | |
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228 | $w = AnyEvent->timer ( |
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229 | after => <fractional_seconds>, |
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230 | interval => <fractional_seconds>, |
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231 | cb => <callback>, |
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232 | ); |
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233 | |
208 | You can create a time watcher by calling the "AnyEvent->timer" method |
234 | You can create a time watcher by calling the "AnyEvent->timer" method |
209 | with the following mandatory arguments: |
235 | with the following mandatory arguments: |
210 | |
236 | |
211 | "after" specifies after how many seconds (fractional values are |
237 | "after" specifies after how many seconds (fractional values are |
212 | supported) the callback should be invoked. "cb" is the callback to |
238 | supported) the callback should be invoked. "cb" is the callback to |
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214 | |
240 | |
215 | Although the callback might get passed parameters, their value and |
241 | Although the callback might get passed parameters, their value and |
216 | presence is undefined and you cannot rely on them. Portable AnyEvent |
242 | presence is undefined and you cannot rely on them. Portable AnyEvent |
217 | callbacks cannot use arguments passed to time watcher callbacks. |
243 | callbacks cannot use arguments passed to time watcher callbacks. |
218 | |
244 | |
219 | The callback will normally be invoked once only. If you specify another |
245 | The callback will normally be invoked only once. If you specify another |
220 | parameter, "interval", as a strictly positive number (> 0), then the |
246 | parameter, "interval", as a strictly positive number (> 0), then the |
221 | callback will be invoked regularly at that interval (in fractional |
247 | callback will be invoked regularly at that interval (in fractional |
222 | seconds) after the first invocation. If "interval" is specified with a |
248 | seconds) after the first invocation. If "interval" is specified with a |
223 | false value, then it is treated as if it were missing. |
249 | false value, then it is treated as if it were not specified at all. |
224 | |
250 | |
225 | The callback will be rescheduled before invoking the callback, but no |
251 | The callback will be rescheduled before invoking the callback, but no |
226 | attempt is done to avoid timer drift in most backends, so the interval |
252 | attempt is made to avoid timer drift in most backends, so the interval |
227 | is only approximate. |
253 | is only approximate. |
228 | |
254 | |
229 | Example: fire an event after 7.7 seconds. |
255 | Example: fire an event after 7.7 seconds. |
230 | |
256 | |
231 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
257 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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237 | |
263 | |
238 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
264 | Example 2: fire an event after 0.5 seconds, then roughly every second. |
239 | |
265 | |
240 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
266 | my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub { |
241 | warn "timeout\n"; |
267 | warn "timeout\n"; |
242 | }; |
268 | }); |
243 | |
269 | |
244 | TIMING ISSUES |
270 | TIMING ISSUES |
245 | There are two ways to handle timers: based on real time (relative, "fire |
271 | There are two ways to handle timers: based on real time (relative, "fire |
246 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
272 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
247 | o'clock"). |
273 | o'clock"). |
248 | |
274 | |
249 | While most event loops expect timers to specified in a relative way, |
275 | While most event loops expect timers to specified in a relative way, |
250 | they use absolute time internally. This makes a difference when your |
276 | they use absolute time internally. This makes a difference when your |
251 | clock "jumps", for example, when ntp decides to set your clock backwards |
277 | clock "jumps", for example, when ntp decides to set your clock backwards |
252 | from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is |
278 | from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is |
253 | supposed to fire "after" a second might actually take six years to |
279 | supposed to fire "after a second" might actually take six years to |
254 | finally fire. |
280 | finally fire. |
255 | |
281 | |
256 | AnyEvent cannot compensate for this. The only event loop that is |
282 | AnyEvent cannot compensate for this. The only event loop that is |
257 | conscious about these issues is EV, which offers both relative |
283 | conscious of these issues is EV, which offers both relative (ev_timer, |
258 | (ev_timer, based on true relative time) and absolute (ev_periodic, based |
284 | based on true relative time) and absolute (ev_periodic, based on |
259 | on wallclock time) timers. |
285 | wallclock time) timers. |
260 | |
286 | |
261 | AnyEvent always prefers relative timers, if available, matching the |
287 | AnyEvent always prefers relative timers, if available, matching the |
262 | AnyEvent API. |
288 | AnyEvent API. |
263 | |
289 | |
264 | AnyEvent has two additional methods that return the "current time": |
290 | AnyEvent has two additional methods that return the "current time": |
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283 | *In almost all cases (in all cases if you don't care), this is the |
309 | *In almost all cases (in all cases if you don't care), this is the |
284 | function to call when you want to know the current time.* |
310 | function to call when you want to know the current time.* |
285 | |
311 | |
286 | This function is also often faster then "AnyEvent->time", and thus |
312 | This function is also often faster then "AnyEvent->time", and thus |
287 | the preferred method if you want some timestamp (for example, |
313 | the preferred method if you want some timestamp (for example, |
288 | AnyEvent::Handle uses this to update it's activity timeouts). |
314 | AnyEvent::Handle uses this to update its activity timeouts). |
289 | |
315 | |
290 | The rest of this section is only of relevance if you try to be very |
316 | The rest of this section is only of relevance if you try to be very |
291 | exact with your timing, you can skip it without bad conscience. |
317 | exact with your timing; you can skip it without a bad conscience. |
292 | |
318 | |
293 | For a practical example of when these times differ, consider |
319 | For a practical example of when these times differ, consider |
294 | Event::Lib and EV and the following set-up: |
320 | Event::Lib and EV and the following set-up: |
295 | |
321 | |
296 | The event loop is running and has just invoked one of your callback |
322 | The event loop is running and has just invoked one of your callbacks |
297 | at time=500 (assume no other callbacks delay processing). In your |
323 | at time=500 (assume no other callbacks delay processing). In your |
298 | callback, you wait a second by executing "sleep 1" (blocking the |
324 | callback, you wait a second by executing "sleep 1" (blocking the |
299 | process for a second) and then (at time=501) you create a relative |
325 | process for a second) and then (at time=501) you create a relative |
300 | timer that fires after three seconds. |
326 | timer that fires after three seconds. |
301 | |
327 | |
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322 | can get whatever behaviour you want with any event loop, by taking |
348 | can get whatever behaviour you want with any event loop, by taking |
323 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
349 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
324 | account. |
350 | account. |
325 | |
351 | |
326 | AnyEvent->now_update |
352 | AnyEvent->now_update |
327 | Some event loops (such as EV or AnyEvent::Impl::Perl) cache the |
353 | Some event loops (such as EV or AnyEvent::Loop) cache the current |
328 | current time for each loop iteration (see the discussion of |
354 | time for each loop iteration (see the discussion of AnyEvent->now, |
329 | AnyEvent->now, above). |
355 | above). |
330 | |
356 | |
331 | When a callback runs for a long time (or when the process sleeps), |
357 | When a callback runs for a long time (or when the process sleeps), |
332 | then this "current" time will differ substantially from the real |
358 | then this "current" time will differ substantially from the real |
333 | time, which might affect timers and time-outs. |
359 | time, which might affect timers and time-outs. |
334 | |
360 | |
335 | When this is the case, you can call this method, which will update |
361 | When this is the case, you can call this method, which will update |
336 | the event loop's idea of "current time". |
362 | the event loop's idea of "current time". |
337 | |
363 | |
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364 | A typical example would be a script in a web server (e.g. |
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365 | "mod_perl") - when mod_perl executes the script, then the event loop |
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366 | will have the wrong idea about the "current time" (being potentially |
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367 | far in the past, when the script ran the last time). In that case |
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368 | you should arrange a call to "AnyEvent->now_update" each time the |
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369 | web server process wakes up again (e.g. at the start of your script, |
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370 | or in a handler). |
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371 | |
338 | Note that updating the time *might* cause some events to be handled. |
372 | Note that updating the time *might* cause some events to be handled. |
339 | |
373 | |
340 | SIGNAL WATCHERS |
374 | SIGNAL WATCHERS |
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375 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
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376 | |
341 | You can watch for signals using a signal watcher, "signal" is the signal |
377 | You can watch for signals using a signal watcher, "signal" is the signal |
342 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
378 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
343 | callback to be invoked whenever a signal occurs. |
379 | callback to be invoked whenever a signal occurs. |
344 | |
380 | |
345 | Although the callback might get passed parameters, their value and |
381 | Although the callback might get passed parameters, their value and |
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350 | invocation, and callback invocation will be synchronous. Synchronous |
386 | invocation, and callback invocation will be synchronous. Synchronous |
351 | means that it might take a while until the signal gets handled by the |
387 | means that it might take a while until the signal gets handled by the |
352 | process, but it is guaranteed not to interrupt any other callbacks. |
388 | process, but it is guaranteed not to interrupt any other callbacks. |
353 | |
389 | |
354 | The main advantage of using these watchers is that you can share a |
390 | The main advantage of using these watchers is that you can share a |
355 | signal between multiple watchers. |
391 | signal between multiple watchers, and AnyEvent will ensure that signals |
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392 | will not interrupt your program at bad times. |
356 | |
393 | |
357 | This watcher might use %SIG, so programs overwriting those signals |
394 | This watcher might use %SIG (depending on the event loop used), so |
358 | directly will likely not work correctly. |
395 | programs overwriting those signals directly will likely not work |
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396 | correctly. |
359 | |
397 | |
360 | Example: exit on SIGINT |
398 | Example: exit on SIGINT |
361 | |
399 | |
362 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
400 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
363 | |
401 | |
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402 | Restart Behaviour |
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403 | While restart behaviour is up to the event loop implementation, most |
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404 | will not restart syscalls (that includes Async::Interrupt and AnyEvent's |
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405 | pure perl implementation). |
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406 | |
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407 | Safe/Unsafe Signals |
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408 | Perl signals can be either "safe" (synchronous to opcode handling) or |
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409 | "unsafe" (asynchronous) - the former might delay signal delivery |
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410 | indefinitely, the latter might corrupt your memory. |
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411 | |
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412 | AnyEvent signal handlers are, in addition, synchronous to the event |
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413 | loop, i.e. they will not interrupt your running perl program but will |
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414 | only be called as part of the normal event handling (just like timer, |
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415 | I/O etc. callbacks, too). |
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416 | |
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417 | Signal Races, Delays and Workarounds |
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418 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
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419 | callbacks to signals in a generic way, which is a pity, as you cannot do |
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420 | race-free signal handling in perl, requiring C libraries for this. |
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421 | AnyEvent will try to do its best, which means in some cases, signals |
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422 | will be delayed. The maximum time a signal might be delayed is 10 |
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423 | seconds by default, but can be overriden via |
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424 | $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} or $AnyEvent::MAX_SIGNAL_LATENCY |
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425 | - see the "ENVIRONMENT VARIABLES" section for details. |
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426 | |
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427 | All these problems can be avoided by installing the optional |
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428 | Async::Interrupt module, which works with most event loops. It will not |
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429 | work with inherently broken event loops such as Event or Event::Lib (and |
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430 | not with POE currently). For those, you just have to suffer the delays. |
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431 | |
364 | CHILD PROCESS WATCHERS |
432 | CHILD PROCESS WATCHERS |
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433 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
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434 | |
365 | You can also watch on a child process exit and catch its exit status. |
435 | You can also watch for a child process exit and catch its exit status. |
366 | |
436 | |
367 | The child process is specified by the "pid" argument (if set to 0, it |
437 | The child process is specified by the "pid" argument (on some backends, |
368 | watches for any child process exit). The watcher will triggered only |
438 | using 0 watches for any child process exit, on others this will croak). |
369 | when the child process has finished and an exit status is available, not |
439 | The watcher will be triggered only when the child process has finished |
370 | on any trace events (stopped/continued). |
440 | and an exit status is available, not on any trace events |
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441 | (stopped/continued). |
371 | |
442 | |
372 | The callback will be called with the pid and exit status (as returned by |
443 | The callback will be called with the pid and exit status (as returned by |
373 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
444 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
374 | callback arguments. |
445 | callback arguments. |
375 | |
446 | |
… | |
… | |
391 | |
462 | |
392 | This means you cannot create a child watcher as the very first thing in |
463 | This means you cannot create a child watcher as the very first thing in |
393 | an AnyEvent program, you *have* to create at least one watcher before |
464 | an AnyEvent program, you *have* to create at least one watcher before |
394 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
465 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
395 | |
466 | |
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467 | As most event loops do not support waiting for child events, they will |
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468 | be emulated by AnyEvent in most cases, in which case the latency and |
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469 | race problems mentioned in the description of signal watchers apply. |
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470 | |
396 | Example: fork a process and wait for it |
471 | Example: fork a process and wait for it |
397 | |
472 | |
398 | my $done = AnyEvent->condvar; |
473 | my $done = AnyEvent->condvar; |
399 | |
474 | |
|
|
475 | # this forks and immediately calls exit in the child. this |
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476 | # normally has all sorts of bad consequences for your parent, |
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|
477 | # so take this as an example only. always fork and exec, |
|
|
478 | # or call POSIX::_exit, in real code. |
400 | my $pid = fork or exit 5; |
479 | my $pid = fork or exit 5; |
401 | |
480 | |
402 | my $w = AnyEvent->child ( |
481 | my $w = AnyEvent->child ( |
403 | pid => $pid, |
482 | pid => $pid, |
404 | cb => sub { |
483 | cb => sub { |
… | |
… | |
410 | |
489 | |
411 | # do something else, then wait for process exit |
490 | # do something else, then wait for process exit |
412 | $done->recv; |
491 | $done->recv; |
413 | |
492 | |
414 | IDLE WATCHERS |
493 | IDLE WATCHERS |
415 | Sometimes there is a need to do something, but it is not so important to |
494 | $w = AnyEvent->idle (cb => <callback>); |
416 | do it instantly, but only when there is nothing better to do. This |
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|
417 | "nothing better to do" is usually defined to be "no other events need |
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418 | attention by the event loop". |
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419 | |
495 | |
420 | Idle watchers ideally get invoked when the event loop has nothing better |
496 | This will repeatedly invoke the callback after the process becomes idle, |
421 | to do, just before it would block the process to wait for new events. |
497 | until either the watcher is destroyed or new events have been detected. |
422 | Instead of blocking, the idle watcher is invoked. |
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|
423 | |
498 | |
424 | Most event loops unfortunately do not really support idle watchers (only |
499 | Idle watchers are useful when there is a need to do something, but it is |
|
|
500 | not so important (or wise) to do it instantly. The callback will be |
|
|
501 | invoked only when there is "nothing better to do", which is usually |
|
|
502 | defined as "all outstanding events have been handled and no new events |
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|
503 | have been detected". That means that idle watchers ideally get invoked |
|
|
504 | when the event loop has just polled for new events but none have been |
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|
505 | detected. Instead of blocking to wait for more events, the idle watchers |
|
|
506 | will be invoked. |
|
|
507 | |
|
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508 | Unfortunately, most event loops do not really support idle watchers |
425 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
509 | (only EV, Event and Glib do it in a usable fashion) - for the rest, |
426 | will simply call the callback "from time to time". |
510 | AnyEvent will simply call the callback "from time to time". |
427 | |
511 | |
428 | Example: read lines from STDIN, but only process them when the program |
512 | Example: read lines from STDIN, but only process them when the program |
429 | is otherwise idle: |
513 | is otherwise idle: |
430 | |
514 | |
431 | my @lines; # read data |
515 | my @lines; # read data |
… | |
… | |
444 | } |
528 | } |
445 | }); |
529 | }); |
446 | }); |
530 | }); |
447 | |
531 | |
448 | CONDITION VARIABLES |
532 | CONDITION VARIABLES |
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533 | $cv = AnyEvent->condvar; |
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534 | |
|
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535 | $cv->send (<list>); |
|
|
536 | my @res = $cv->recv; |
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537 | |
449 | If you are familiar with some event loops you will know that all of them |
538 | If you are familiar with some event loops you will know that all of them |
450 | require you to run some blocking "loop", "run" or similar function that |
539 | require you to run some blocking "loop", "run" or similar function that |
451 | will actively watch for new events and call your callbacks. |
540 | will actively watch for new events and call your callbacks. |
452 | |
541 | |
453 | AnyEvent is slightly different: it expects somebody else to run the |
542 | AnyEvent is slightly different: it expects somebody else to run the |
454 | event loop and will only block when necessary (usually when told by the |
543 | event loop and will only block when necessary (usually when told by the |
455 | user). |
544 | user). |
456 | |
545 | |
457 | The instrument to do that is called a "condition variable", so called |
546 | The tool to do that is called a "condition variable", so called because |
458 | because they represent a condition that must become true. |
547 | they represent a condition that must become true. |
459 | |
548 | |
460 | Now is probably a good time to look at the examples further below. |
549 | Now is probably a good time to look at the examples further below. |
461 | |
550 | |
462 | Condition variables can be created by calling the "AnyEvent->condvar" |
551 | Condition variables can be created by calling the "AnyEvent->condvar" |
463 | method, usually without arguments. The only argument pair allowed is |
552 | method, usually without arguments. The only argument pair allowed is |
… | |
… | |
468 | After creation, the condition variable is "false" until it becomes |
557 | After creation, the condition variable is "false" until it becomes |
469 | "true" by calling the "send" method (or calling the condition variable |
558 | "true" by calling the "send" method (or calling the condition variable |
470 | as if it were a callback, read about the caveats in the description for |
559 | as if it were a callback, read about the caveats in the description for |
471 | the "->send" method). |
560 | the "->send" method). |
472 | |
561 | |
473 | Condition variables are similar to callbacks, except that you can |
562 | Since condition variables are the most complex part of the AnyEvent API, |
474 | optionally wait for them. They can also be called merge points - points |
563 | here are some different mental models of what they are - pick the ones |
475 | in time where multiple outstanding events have been processed. And yet |
564 | you can connect to: |
476 | another way to call them is transactions - each condition variable can |
565 | |
477 | be used to represent a transaction, which finishes at some point and |
566 | * Condition variables are like callbacks - you can call them (and pass |
478 | delivers a result. |
567 | them instead of callbacks). Unlike callbacks however, you can also |
|
|
568 | wait for them to be called. |
|
|
569 | |
|
|
570 | * Condition variables are signals - one side can emit or send them, |
|
|
571 | the other side can wait for them, or install a handler that is |
|
|
572 | called when the signal fires. |
|
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573 | |
|
|
574 | * Condition variables are like "Merge Points" - points in your program |
|
|
575 | where you merge multiple independent results/control flows into one. |
|
|
576 | |
|
|
577 | * Condition variables represent a transaction - functions that start |
|
|
578 | some kind of transaction can return them, leaving the caller the |
|
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579 | choice between waiting in a blocking fashion, or setting a callback. |
|
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580 | |
|
|
581 | * Condition variables represent future values, or promises to deliver |
|
|
582 | some result, long before the result is available. |
479 | |
583 | |
480 | Condition variables are very useful to signal that something has |
584 | Condition variables are very useful to signal that something has |
481 | finished, for example, if you write a module that does asynchronous http |
585 | finished, for example, if you write a module that does asynchronous http |
482 | requests, then a condition variable would be the ideal candidate to |
586 | requests, then a condition variable would be the ideal candidate to |
483 | signal the availability of results. The user can either act when the |
587 | signal the availability of results. The user can either act when the |
… | |
… | |
496 | |
600 | |
497 | Condition variables are represented by hash refs in perl, and the keys |
601 | Condition variables are represented by hash refs in perl, and the keys |
498 | used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy |
602 | used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy |
499 | (it is often useful to build your own transaction class on top of |
603 | (it is often useful to build your own transaction class on top of |
500 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
604 | AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call |
501 | it's "new" method in your own "new" method. |
605 | its "new" method in your own "new" method. |
502 | |
606 | |
503 | There are two "sides" to a condition variable - the "producer side" |
607 | There are two "sides" to a condition variable - the "producer side" |
504 | which eventually calls "-> send", and the "consumer side", which waits |
608 | which eventually calls "-> send", and the "consumer side", which waits |
505 | for the send to occur. |
609 | for the send to occur. |
506 | |
610 | |
507 | Example: wait for a timer. |
611 | Example: wait for a timer. |
508 | |
612 | |
509 | # wait till the result is ready |
613 | # condition: "wait till the timer is fired" |
510 | my $result_ready = AnyEvent->condvar; |
614 | my $timer_fired = AnyEvent->condvar; |
511 | |
615 | |
512 | # do something such as adding a timer |
616 | # create the timer - we could wait for, say |
513 | # or socket watcher the calls $result_ready->send |
617 | # a handle becomign ready, or even an |
514 | # when the "result" is ready. |
618 | # AnyEvent::HTTP request to finish, but |
515 | # in this case, we simply use a timer: |
619 | # in this case, we simply use a timer: |
516 | my $w = AnyEvent->timer ( |
620 | my $w = AnyEvent->timer ( |
517 | after => 1, |
621 | after => 1, |
518 | cb => sub { $result_ready->send }, |
622 | cb => sub { $timer_fired->send }, |
519 | ); |
623 | ); |
520 | |
624 | |
521 | # this "blocks" (while handling events) till the callback |
625 | # this "blocks" (while handling events) till the callback |
522 | # calls -<send |
626 | # calls ->send |
523 | $result_ready->recv; |
627 | $timer_fired->recv; |
524 | |
628 | |
525 | Example: wait for a timer, but take advantage of the fact that condition |
629 | Example: wait for a timer, but take advantage of the fact that condition |
526 | variables are also callable directly. |
630 | variables are also callable directly. |
527 | |
631 | |
528 | my $done = AnyEvent->condvar; |
632 | my $done = AnyEvent->condvar; |
… | |
… | |
566 | Condition variables are overloaded so one can call them directly (as |
670 | Condition variables are overloaded so one can call them directly (as |
567 | if they were a code reference). Calling them directly is the same as |
671 | if they were a code reference). Calling them directly is the same as |
568 | calling "send". |
672 | calling "send". |
569 | |
673 | |
570 | $cv->croak ($error) |
674 | $cv->croak ($error) |
571 | Similar to send, but causes all call's to "->recv" to invoke |
675 | Similar to send, but causes all calls to "->recv" to invoke |
572 | "Carp::croak" with the given error message/object/scalar. |
676 | "Carp::croak" with the given error message/object/scalar. |
573 | |
677 | |
574 | This can be used to signal any errors to the condition variable |
678 | This can be used to signal any errors to the condition variable |
575 | user/consumer. Doing it this way instead of calling "croak" directly |
679 | user/consumer. Doing it this way instead of calling "croak" directly |
576 | delays the error detetcion, but has the overwhelmign advantage that |
680 | delays the error detection, but has the overwhelming advantage that |
577 | it diagnoses the error at the place where the result is expected, |
681 | it diagnoses the error at the place where the result is expected, |
578 | and not deep in some event clalback without connection to the actual |
682 | and not deep in some event callback with no connection to the actual |
579 | code causing the problem. |
683 | code causing the problem. |
580 | |
684 | |
581 | $cv->begin ([group callback]) |
685 | $cv->begin ([group callback]) |
582 | $cv->end |
686 | $cv->end |
583 | These two methods can be used to combine many transactions/events |
687 | These two methods can be used to combine many transactions/events |
584 | into one. For example, a function that pings many hosts in parallel |
688 | into one. For example, a function that pings many hosts in parallel |
585 | might want to use a condition variable for the whole process. |
689 | might want to use a condition variable for the whole process. |
586 | |
690 | |
587 | Every call to "->begin" will increment a counter, and every call to |
691 | Every call to "->begin" will increment a counter, and every call to |
588 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
692 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
589 | (last) callback passed to "begin" will be executed. That callback is |
693 | (last) callback passed to "begin" will be executed, passing the |
590 | *supposed* to call "->send", but that is not required. If no |
694 | condvar as first argument. That callback is *supposed* to call |
|
|
695 | "->send", but that is not required. If no group callback was set, |
591 | callback was set, "send" will be called without any arguments. |
696 | "send" will be called without any arguments. |
592 | |
697 | |
593 | You can think of "$cv->send" giving you an OR condition (one call |
698 | You can think of "$cv->send" giving you an OR condition (one call |
594 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
699 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
595 | condition (all "begin" calls must be "end"'ed before the condvar |
700 | condition (all "begin" calls must be "end"'ed before the condvar |
596 | sends). |
701 | sends). |
… | |
… | |
618 | This works because for every event source (EOF on file handle), |
723 | This works because for every event source (EOF on file handle), |
619 | there is one call to "begin", so the condvar waits for all calls to |
724 | there is one call to "begin", so the condvar waits for all calls to |
620 | "end" before sending. |
725 | "end" before sending. |
621 | |
726 | |
622 | The ping example mentioned above is slightly more complicated, as |
727 | The ping example mentioned above is slightly more complicated, as |
623 | the there are results to be passwd back, and the number of tasks |
728 | the there are results to be passed back, and the number of tasks |
624 | that are begung can potentially be zero: |
729 | that are begun can potentially be zero: |
625 | |
730 | |
626 | my $cv = AnyEvent->condvar; |
731 | my $cv = AnyEvent->condvar; |
627 | |
732 | |
628 | my %result; |
733 | my %result; |
629 | $cv->begin (sub { $cv->send (\%result) }); |
734 | $cv->begin (sub { shift->send (\%result) }); |
630 | |
735 | |
631 | for my $host (@list_of_hosts) { |
736 | for my $host (@list_of_hosts) { |
632 | $cv->begin; |
737 | $cv->begin; |
633 | ping_host_then_call_callback $host, sub { |
738 | ping_host_then_call_callback $host, sub { |
634 | $result{$host} = ...; |
739 | $result{$host} = ...; |
… | |
… | |
636 | }; |
741 | }; |
637 | } |
742 | } |
638 | |
743 | |
639 | $cv->end; |
744 | $cv->end; |
640 | |
745 | |
|
|
746 | ... |
|
|
747 | |
|
|
748 | my $results = $cv->recv; |
|
|
749 | |
641 | This code fragment supposedly pings a number of hosts and calls |
750 | This code fragment supposedly pings a number of hosts and calls |
642 | "send" after results for all then have have been gathered - in any |
751 | "send" after results for all then have have been gathered - in any |
643 | order. To achieve this, the code issues a call to "begin" when it |
752 | order. To achieve this, the code issues a call to "begin" when it |
644 | starts each ping request and calls "end" when it has received some |
753 | starts each ping request and calls "end" when it has received some |
645 | result for it. Since "begin" and "end" only maintain a counter, the |
754 | result for it. Since "begin" and "end" only maintain a counter, the |
… | |
… | |
650 | callback to be called once the counter reaches 0, and second, it |
759 | callback to be called once the counter reaches 0, and second, it |
651 | ensures that "send" is called even when "no" hosts are being pinged |
760 | ensures that "send" is called even when "no" hosts are being pinged |
652 | (the loop doesn't execute once). |
761 | (the loop doesn't execute once). |
653 | |
762 | |
654 | This is the general pattern when you "fan out" into multiple (but |
763 | This is the general pattern when you "fan out" into multiple (but |
655 | potentially none) subrequests: use an outer "begin"/"end" pair to |
764 | potentially zero) subrequests: use an outer "begin"/"end" pair to |
656 | set the callback and ensure "end" is called at least once, and then, |
765 | set the callback and ensure "end" is called at least once, and then, |
657 | for each subrequest you start, call "begin" and for each subrequest |
766 | for each subrequest you start, call "begin" and for each subrequest |
658 | you finish, call "end". |
767 | you finish, call "end". |
659 | |
768 | |
660 | METHODS FOR CONSUMERS |
769 | METHODS FOR CONSUMERS |
661 | These methods should only be used by the consuming side, i.e. the code |
770 | These methods should only be used by the consuming side, i.e. the code |
662 | awaits the condition. |
771 | awaits the condition. |
663 | |
772 | |
664 | $cv->recv |
773 | $cv->recv |
665 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
774 | Wait (blocking if necessary) until the "->send" or "->croak" methods |
666 | have been called on c<$cv>, while servicing other watchers normally. |
775 | have been called on $cv, while servicing other watchers normally. |
667 | |
776 | |
668 | You can only wait once on a condition - additional calls are valid |
777 | You can only wait once on a condition - additional calls are valid |
669 | but will return immediately. |
778 | but will return immediately. |
670 | |
779 | |
671 | If an error condition has been set by calling "->croak", then this |
780 | If an error condition has been set by calling "->croak", then this |
… | |
… | |
674 | In list context, all parameters passed to "send" will be returned, |
783 | In list context, all parameters passed to "send" will be returned, |
675 | in scalar context only the first one will be returned. |
784 | in scalar context only the first one will be returned. |
676 | |
785 | |
677 | Note that doing a blocking wait in a callback is not supported by |
786 | Note that doing a blocking wait in a callback is not supported by |
678 | any event loop, that is, recursive invocation of a blocking "->recv" |
787 | any event loop, that is, recursive invocation of a blocking "->recv" |
679 | is not allowed, and the "recv" call will "croak" if such a condition |
788 | is not allowed and the "recv" call will "croak" if such a condition |
680 | is detected. This condition can be slightly loosened by using |
789 | is detected. This requirement can be dropped by relying on |
681 | Coro::AnyEvent, which allows you to do a blocking "->recv" from any |
790 | Coro::AnyEvent , which allows you to do a blocking "->recv" from any |
682 | thread that doesn't run the event loop itself. |
791 | thread that doesn't run the event loop itself. Coro::AnyEvent is |
|
|
792 | loaded automatically when Coro is used with AnyEvent, so code does |
|
|
793 | not need to do anything special to take advantage of that: any code |
|
|
794 | that would normally block your program because it calls "recv", be |
|
|
795 | executed in an "async" thread instead without blocking other |
|
|
796 | threads. |
683 | |
797 | |
684 | Not all event models support a blocking wait - some die in that case |
798 | Not all event models support a blocking wait - some die in that case |
685 | (programs might want to do that to stay interactive), so *if you are |
799 | (programs might want to do that to stay interactive), so *if you are |
686 | using this from a module, never require a blocking wait*. Instead, |
800 | using this from a module, never require a blocking wait*. Instead, |
687 | let the caller decide whether the call will block or not (for |
801 | let the caller decide whether the call will block or not (for |
688 | example, by coupling condition variables with some kind of request |
802 | example, by coupling condition variables with some kind of request |
689 | results and supporting callbacks so the caller knows that getting |
803 | results and supporting callbacks so the caller knows that getting |
690 | the result will not block, while still supporting blocking waits if |
804 | the result will not block, while still supporting blocking waits if |
691 | the caller so desires). |
805 | the caller so desires). |
692 | |
806 | |
693 | You can ensure that "-recv" never blocks by setting a callback and |
807 | You can ensure that "->recv" never blocks by setting a callback and |
694 | only calling "->recv" from within that callback (or at a later |
808 | only calling "->recv" from within that callback (or at a later |
695 | time). This will work even when the event loop does not support |
809 | time). This will work even when the event loop does not support |
696 | blocking waits otherwise. |
810 | blocking waits otherwise. |
697 | |
811 | |
698 | $bool = $cv->ready |
812 | $bool = $cv->ready |
699 | Returns true when the condition is "true", i.e. whether "send" or |
813 | Returns true when the condition is "true", i.e. whether "send" or |
700 | "croak" have been called. |
814 | "croak" have been called. |
701 | |
815 | |
702 | $cb = $cv->cb ($cb->($cv)) |
816 | $cb = $cv->cb ($cb->($cv)) |
703 | This is a mutator function that returns the callback set and |
817 | This is a mutator function that returns the callback set (or "undef" |
704 | optionally replaces it before doing so. |
818 | if not) and optionally replaces it before doing so. |
705 | |
819 | |
706 | The callback will be called when the condition becomes "true", i.e. |
820 | The callback will be called when the condition becomes "true", i.e. |
707 | when "send" or "croak" are called, with the only argument being the |
821 | when "send" or "croak" are called, with the only argument being the |
708 | condition variable itself. Calling "recv" inside the callback or at |
822 | condition variable itself. If the condition is already true, the |
|
|
823 | callback is called immediately when it is set. Calling "recv" inside |
709 | any later time is guaranteed not to block. |
824 | the callback or at any later time is guaranteed not to block. |
|
|
825 | |
|
|
826 | Additionally, when the callback is invoked, it is also removed from |
|
|
827 | the condvar (reset to "undef"), so the condvar does not keep a |
|
|
828 | reference to the callback after invocation. |
710 | |
829 | |
711 | SUPPORTED EVENT LOOPS/BACKENDS |
830 | SUPPORTED EVENT LOOPS/BACKENDS |
712 | The available backend classes are (every class has its own manpage): |
831 | The available backend classes are (every class has its own manpage): |
713 | |
832 | |
714 | Backends that are autoprobed when no other event loop can be found. |
833 | Backends that are autoprobed when no other event loop can be found. |
715 | EV is the preferred backend when no other event loop seems to be in |
834 | EV is the preferred backend when no other event loop seems to be in |
716 | use. If EV is not installed, then AnyEvent will try Event, and, |
835 | use. If EV is not installed, then AnyEvent will fall back to its own |
717 | failing that, will fall back to its own pure-perl implementation, |
836 | pure-perl implementation, which is available everywhere as it comes |
718 | which is available everywhere as it comes with AnyEvent itself. |
837 | with AnyEvent itself. |
719 | |
838 | |
720 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
839 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
721 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
722 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
840 | AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable. |
723 | |
841 | |
724 | Backends that are transparently being picked up when they are used. |
842 | Backends that are transparently being picked up when they are used. |
725 | These will be used when they are currently loaded when the first |
843 | These will be used if they are already loaded when the first watcher |
726 | watcher is created, in which case it is assumed that the application |
844 | is created, in which case it is assumed that the application is |
727 | is using them. This means that AnyEvent will automatically pick the |
845 | using them. This means that AnyEvent will automatically pick the |
728 | right backend when the main program loads an event module before |
846 | right backend when the main program loads an event module before |
729 | anything starts to create watchers. Nothing special needs to be done |
847 | anything starts to create watchers. Nothing special needs to be done |
730 | by the main program. |
848 | by the main program. |
731 | |
849 | |
|
|
850 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
732 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
851 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
733 | AnyEvent::Impl::Tk based on Tk, very broken. |
852 | AnyEvent::Impl::Tk based on Tk, very broken. |
|
|
853 | AnyEvent::Impl::UV based on UV, innovated square wheels. |
734 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
854 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
735 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
855 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
856 | AnyEvent::Impl::Irssi used when running within irssi. |
|
|
857 | AnyEvent::Impl::IOAsync based on IO::Async. |
|
|
858 | AnyEvent::Impl::Cocoa based on Cocoa::EventLoop. |
|
|
859 | AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding). |
736 | |
860 | |
737 | Backends with special needs. |
861 | Backends with special needs. |
738 | Qt requires the Qt::Application to be instantiated first, but will |
862 | Qt requires the Qt::Application to be instantiated first, but will |
739 | otherwise be picked up automatically. As long as the main program |
863 | otherwise be picked up automatically. As long as the main program |
740 | instantiates the application before any AnyEvent watchers are |
864 | instantiates the application before any AnyEvent watchers are |
741 | created, everything should just work. |
865 | created, everything should just work. |
742 | |
866 | |
743 | AnyEvent::Impl::Qt based on Qt. |
867 | AnyEvent::Impl::Qt based on Qt. |
744 | |
868 | |
745 | Support for IO::Async can only be partial, as it is too broken and |
|
|
746 | architecturally limited to even support the AnyEvent API. It also is |
|
|
747 | the only event loop that needs the loop to be set explicitly, so it |
|
|
748 | can only be used by a main program knowing about AnyEvent. See |
|
|
749 | AnyEvent::Impl::Async for the gory details. |
|
|
750 | |
|
|
751 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
752 | |
|
|
753 | Event loops that are indirectly supported via other backends. |
869 | Event loops that are indirectly supported via other backends. |
754 | Some event loops can be supported via other modules: |
870 | Some event loops can be supported via other modules: |
755 | |
871 | |
756 | There is no direct support for WxWidgets (Wx) or Prima. |
872 | There is no direct support for WxWidgets (Wx) or Prima. |
757 | |
873 | |
… | |
… | |
775 | Contains "undef" until the first watcher is being created, before |
891 | Contains "undef" until the first watcher is being created, before |
776 | the backend has been autodetected. |
892 | the backend has been autodetected. |
777 | |
893 | |
778 | Afterwards it contains the event model that is being used, which is |
894 | Afterwards it contains the event model that is being used, which is |
779 | the name of the Perl class implementing the model. This class is |
895 | the name of the Perl class implementing the model. This class is |
780 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
896 | usually one of the "AnyEvent::Impl::xxx" modules, but can be any |
781 | other class in the case AnyEvent has been extended at runtime (e.g. |
897 | other class in the case AnyEvent has been extended at runtime (e.g. |
782 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
898 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
783 | |
899 | |
784 | AnyEvent::detect |
900 | AnyEvent::detect |
785 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
901 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
786 | if necessary. You should only call this function right before you |
902 | if necessary. You should only call this function right before you |
787 | would have created an AnyEvent watcher anyway, that is, as late as |
903 | would have created an AnyEvent watcher anyway, that is, as late as |
788 | possible at runtime, and not e.g. while initialising of your module. |
904 | possible at runtime, and not e.g. during initialisation of your |
|
|
905 | module. |
|
|
906 | |
|
|
907 | The effect of calling this function is as if a watcher had been |
|
|
908 | created (specifically, actions that happen "when the first watcher |
|
|
909 | is created" happen when calling detetc as well). |
789 | |
910 | |
790 | If you need to do some initialisation before AnyEvent watchers are |
911 | If you need to do some initialisation before AnyEvent watchers are |
791 | created, use "post_detect". |
912 | created, use "post_detect". |
792 | |
913 | |
793 | $guard = AnyEvent::post_detect { BLOCK } |
914 | $guard = AnyEvent::post_detect { BLOCK } |
794 | Arranges for the code block to be executed as soon as the event |
915 | Arranges for the code block to be executed as soon as the event |
795 | model is autodetected (or immediately if this has already happened). |
916 | model is autodetected (or immediately if that has already happened). |
796 | |
917 | |
797 | The block will be executed *after* the actual backend has been |
918 | The block will be executed *after* the actual backend has been |
798 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
919 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
799 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
920 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
800 | other initialisations - see the sources of AnyEvent::Strict or |
921 | other initialisations - see the sources of AnyEvent::Strict or |
… | |
… | |
805 | creates and installs the global IO::AIO watcher in a "post_detect" |
926 | creates and installs the global IO::AIO watcher in a "post_detect" |
806 | block to avoid autodetecting the event module at load time. |
927 | block to avoid autodetecting the event module at load time. |
807 | |
928 | |
808 | If called in scalar or list context, then it creates and returns an |
929 | If called in scalar or list context, then it creates and returns an |
809 | object that automatically removes the callback again when it is |
930 | object that automatically removes the callback again when it is |
|
|
931 | destroyed (or "undef" when the hook was immediately executed). See |
810 | destroyed. See Coro::BDB for a case where this is useful. |
932 | AnyEvent::AIO for a case where this is useful. |
|
|
933 | |
|
|
934 | Example: Create a watcher for the IO::AIO module and store it in |
|
|
935 | $WATCHER, but do so only do so after the event loop is initialised. |
|
|
936 | |
|
|
937 | our WATCHER; |
|
|
938 | |
|
|
939 | my $guard = AnyEvent::post_detect { |
|
|
940 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
|
|
941 | }; |
|
|
942 | |
|
|
943 | # the ||= is important in case post_detect immediately runs the block, |
|
|
944 | # as to not clobber the newly-created watcher. assigning both watcher and |
|
|
945 | # post_detect guard to the same variable has the advantage of users being |
|
|
946 | # able to just C<undef $WATCHER> if the watcher causes them grief. |
|
|
947 | |
|
|
948 | $WATCHER ||= $guard; |
811 | |
949 | |
812 | @AnyEvent::post_detect |
950 | @AnyEvent::post_detect |
813 | If there are any code references in this array (you can "push" to it |
951 | If there are any code references in this array (you can "push" to it |
814 | before or after loading AnyEvent), then they will called directly |
952 | before or after loading AnyEvent), then they will be called directly |
815 | after the event loop has been chosen. |
953 | after the event loop has been chosen. |
816 | |
954 | |
817 | You should check $AnyEvent::MODEL before adding to this array, |
955 | You should check $AnyEvent::MODEL before adding to this array, |
818 | though: if it is defined then the event loop has already been |
956 | though: if it is defined then the event loop has already been |
819 | detected, and the array will be ignored. |
957 | detected, and the array will be ignored. |
820 | |
958 | |
821 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
959 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
822 | allows it,as it takes care of these details. |
960 | allows it, as it takes care of these details. |
823 | |
961 | |
824 | This variable is mainly useful for modules that can do something |
962 | This variable is mainly useful for modules that can do something |
825 | useful when AnyEvent is used and thus want to know when it is |
963 | useful when AnyEvent is used and thus want to know when it is |
826 | initialised, but do not need to even load it by default. This array |
964 | initialised, but do not need to even load it by default. This array |
827 | provides the means to hook into AnyEvent passively, without loading |
965 | provides the means to hook into AnyEvent passively, without loading |
828 | it. |
966 | it. |
829 | |
967 | |
|
|
968 | Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used |
|
|
969 | together, you could put this into Coro (this is the actual code used |
|
|
970 | by Coro to accomplish this): |
|
|
971 | |
|
|
972 | if (defined $AnyEvent::MODEL) { |
|
|
973 | # AnyEvent already initialised, so load Coro::AnyEvent |
|
|
974 | require Coro::AnyEvent; |
|
|
975 | } else { |
|
|
976 | # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent |
|
|
977 | # as soon as it is |
|
|
978 | push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; |
|
|
979 | } |
|
|
980 | |
|
|
981 | AnyEvent::postpone { BLOCK } |
|
|
982 | Arranges for the block to be executed as soon as possible, but not |
|
|
983 | before the call itself returns. In practise, the block will be |
|
|
984 | executed just before the event loop polls for new events, or shortly |
|
|
985 | afterwards. |
|
|
986 | |
|
|
987 | This function never returns anything (to make the "return postpone { |
|
|
988 | ... }" idiom more useful. |
|
|
989 | |
|
|
990 | To understand the usefulness of this function, consider a function |
|
|
991 | that asynchronously does something for you and returns some |
|
|
992 | transaction object or guard to let you cancel the operation. For |
|
|
993 | example, "AnyEvent::Socket::tcp_connect": |
|
|
994 | |
|
|
995 | # start a connection attempt unless one is active |
|
|
996 | $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub { |
|
|
997 | delete $self->{connect_guard}; |
|
|
998 | ... |
|
|
999 | }; |
|
|
1000 | |
|
|
1001 | Imagine that this function could instantly call the callback, for |
|
|
1002 | example, because it detects an obvious error such as a negative port |
|
|
1003 | number. Invoking the callback before the function returns causes |
|
|
1004 | problems however: the callback will be called and will try to delete |
|
|
1005 | the guard object. But since the function hasn't returned yet, there |
|
|
1006 | is nothing to delete. When the function eventually returns it will |
|
|
1007 | assign the guard object to "$self->{connect_guard}", where it will |
|
|
1008 | likely never be deleted, so the program thinks it is still trying to |
|
|
1009 | connect. |
|
|
1010 | |
|
|
1011 | This is where "AnyEvent::postpone" should be used. Instead of |
|
|
1012 | calling the callback directly on error: |
|
|
1013 | |
|
|
1014 | $cb->(undef), return # signal error to callback, BAD! |
|
|
1015 | if $some_error_condition; |
|
|
1016 | |
|
|
1017 | It should use "postpone": |
|
|
1018 | |
|
|
1019 | AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later |
|
|
1020 | if $some_error_condition; |
|
|
1021 | |
|
|
1022 | AnyEvent::log $level, $msg[, @args] |
|
|
1023 | Log the given $msg at the given $level. |
|
|
1024 | |
|
|
1025 | If AnyEvent::Log is not loaded then this function makes a simple |
|
|
1026 | test to see whether the message will be logged. If the test succeeds |
|
|
1027 | it will load AnyEvent::Log and call "AnyEvent::Log::log" - |
|
|
1028 | consequently, look at the AnyEvent::Log documentation for details. |
|
|
1029 | |
|
|
1030 | If the test fails it will simply return. Right now this happens when |
|
|
1031 | a numerical loglevel is used and it is larger than the level |
|
|
1032 | specified via $ENV{PERL_ANYEVENT_VERBOSE}. |
|
|
1033 | |
|
|
1034 | If you want to sprinkle loads of logging calls around your code, |
|
|
1035 | consider creating a logger callback with the "AnyEvent::Log::logger" |
|
|
1036 | function, which can reduce typing, codesize and can reduce the |
|
|
1037 | logging overhead enourmously. |
|
|
1038 | |
|
|
1039 | AnyEvent::fh_block $filehandle |
|
|
1040 | AnyEvent::fh_unblock $filehandle |
|
|
1041 | Sets blocking or non-blocking behaviour for the given filehandle. |
|
|
1042 | |
830 | WHAT TO DO IN A MODULE |
1043 | WHAT TO DO IN A MODULE |
831 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
1044 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
832 | freely, but you should not load a specific event module or rely on it. |
1045 | freely, but you should not load a specific event module or rely on it. |
833 | |
1046 | |
834 | Be careful when you create watchers in the module body - AnyEvent will |
1047 | Be careful when you create watchers in the module body - AnyEvent will |
… | |
… | |
841 | stall the whole program, and the whole point of using events is to stay |
1054 | stall the whole program, and the whole point of using events is to stay |
842 | interactive. |
1055 | interactive. |
843 | |
1056 | |
844 | It is fine, however, to call "->recv" when the user of your module |
1057 | It is fine, however, to call "->recv" when the user of your module |
845 | requests it (i.e. if you create a http request object ad have a method |
1058 | requests it (i.e. if you create a http request object ad have a method |
846 | called "results" that returns the results, it should call "->recv" |
1059 | called "results" that returns the results, it may call "->recv" freely, |
847 | freely, as the user of your module knows what she is doing. always). |
1060 | as the user of your module knows what she is doing. Always). |
848 | |
1061 | |
849 | WHAT TO DO IN THE MAIN PROGRAM |
1062 | WHAT TO DO IN THE MAIN PROGRAM |
850 | There will always be a single main program - the only place that should |
1063 | There will always be a single main program - the only place that should |
851 | dictate which event model to use. |
1064 | dictate which event model to use. |
852 | |
1065 | |
853 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
1066 | If the program is not event-based, it need not do anything special, even |
854 | do anything special (it does not need to be event-based) and let |
1067 | when it depends on a module that uses an AnyEvent. If the program itself |
855 | AnyEvent decide which implementation to chose if some module relies on |
1068 | uses AnyEvent, but does not care which event loop is used, all it needs |
856 | it. |
1069 | to do is "use AnyEvent". In either case, AnyEvent will choose the best |
|
|
1070 | available loop implementation. |
857 | |
1071 | |
858 | If the main program relies on a specific event model - for example, in |
1072 | If the main program relies on a specific event model - for example, in |
859 | Gtk2 programs you have to rely on the Glib module - you should load the |
1073 | Gtk2 programs you have to rely on the Glib module - you should load the |
860 | event module before loading AnyEvent or any module that uses it: |
1074 | event module before loading AnyEvent or any module that uses it: |
861 | generally speaking, you should load it as early as possible. The reason |
1075 | generally speaking, you should load it as early as possible. The reason |
862 | is that modules might create watchers when they are loaded, and AnyEvent |
1076 | is that modules might create watchers when they are loaded, and AnyEvent |
863 | will decide on the event model to use as soon as it creates watchers, |
1077 | will decide on the event model to use as soon as it creates watchers, |
864 | and it might chose the wrong one unless you load the correct one |
1078 | and it might choose the wrong one unless you load the correct one |
865 | yourself. |
1079 | yourself. |
866 | |
1080 | |
867 | You can chose to use a pure-perl implementation by loading the |
1081 | You can chose to use a pure-perl implementation by loading the |
868 | "AnyEvent::Impl::Perl" module, which gives you similar behaviour |
1082 | "AnyEvent::Loop" module, which gives you similar behaviour everywhere, |
869 | everywhere, but letting AnyEvent chose the model is generally better. |
1083 | but letting AnyEvent chose the model is generally better. |
870 | |
1084 | |
871 | MAINLOOP EMULATION |
1085 | MAINLOOP EMULATION |
872 | Sometimes (often for short test scripts, or even standalone programs who |
1086 | Sometimes (often for short test scripts, or even standalone programs who |
873 | only want to use AnyEvent), you do not want to run a specific event |
1087 | only want to use AnyEvent), you do not want to run a specific event |
874 | loop. |
1088 | loop. |
… | |
… | |
886 | |
1100 | |
887 | OTHER MODULES |
1101 | OTHER MODULES |
888 | The following is a non-exhaustive list of additional modules that use |
1102 | The following is a non-exhaustive list of additional modules that use |
889 | AnyEvent as a client and can therefore be mixed easily with other |
1103 | AnyEvent as a client and can therefore be mixed easily with other |
890 | AnyEvent modules and other event loops in the same program. Some of the |
1104 | AnyEvent modules and other event loops in the same program. Some of the |
891 | modules come with AnyEvent, most are available via CPAN. |
1105 | modules come as part of AnyEvent, the others are available via CPAN (see |
|
|
1106 | <http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for a longer |
|
|
1107 | non-exhaustive list), and the list is heavily biased towards modules of |
|
|
1108 | the AnyEvent author himself :) |
892 | |
1109 | |
893 | AnyEvent::Util |
1110 | AnyEvent::Util (part of the AnyEvent distribution) |
894 | Contains various utility functions that replace often-used but |
1111 | Contains various utility functions that replace often-used blocking |
895 | blocking functions such as "inet_aton" by event-/callback-based |
1112 | functions such as "inet_aton" with event/callback-based versions. |
896 | versions. |
|
|
897 | |
1113 | |
898 | AnyEvent::Socket |
1114 | AnyEvent::Socket (part of the AnyEvent distribution) |
899 | Provides various utility functions for (internet protocol) sockets, |
1115 | Provides various utility functions for (internet protocol) sockets, |
900 | addresses and name resolution. Also functions to create non-blocking |
1116 | addresses and name resolution. Also functions to create non-blocking |
901 | tcp connections or tcp servers, with IPv6 and SRV record support and |
1117 | tcp connections or tcp servers, with IPv6 and SRV record support and |
902 | more. |
1118 | more. |
903 | |
1119 | |
904 | AnyEvent::Handle |
1120 | AnyEvent::Handle (part of the AnyEvent distribution) |
905 | Provide read and write buffers, manages watchers for reads and |
1121 | Provide read and write buffers, manages watchers for reads and |
906 | writes, supports raw and formatted I/O, I/O queued and fully |
1122 | writes, supports raw and formatted I/O, I/O queued and fully |
907 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
1123 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS). |
908 | |
1124 | |
909 | AnyEvent::DNS |
1125 | AnyEvent::DNS (part of the AnyEvent distribution) |
910 | Provides rich asynchronous DNS resolver capabilities. |
1126 | Provides rich asynchronous DNS resolver capabilities. |
911 | |
1127 | |
912 | AnyEvent::HTTP |
1128 | AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD, |
913 | A simple-to-use HTTP library that is capable of making a lot of |
1129 | AnyEvent::IGS, AnyEvent::FCP |
914 | concurrent HTTP requests. |
1130 | Implement event-based interfaces to the protocols of the same name |
|
|
1131 | (for the curious, IGS is the International Go Server and FCP is the |
|
|
1132 | Freenet Client Protocol). |
915 | |
1133 | |
|
|
1134 | AnyEvent::AIO (part of the AnyEvent distribution) |
|
|
1135 | Truly asynchronous (as opposed to non-blocking) I/O, should be in |
|
|
1136 | the toolbox of every event programmer. AnyEvent::AIO transparently |
|
|
1137 | fuses IO::AIO and AnyEvent together, giving AnyEvent access to |
|
|
1138 | event-based file I/O, and much more. |
|
|
1139 | |
|
|
1140 | AnyEvent::Fork, AnyEvent::Fork::RPC, AnyEvent::Fork::Pool, |
|
|
1141 | AnyEvent::Fork::Remote |
|
|
1142 | These let you safely fork new subprocesses, either locally or |
|
|
1143 | remotely (e.g.v ia ssh), using some RPC protocol or not, without the |
|
|
1144 | limitations normally imposed by fork (AnyEvent works fine for |
|
|
1145 | example). Dynamically-resized worker pools are obviously included as |
|
|
1146 | well. |
|
|
1147 | |
|
|
1148 | And they are quite tiny and fast as well - "abusing" AnyEvent::Fork |
|
|
1149 | just to exec external programs can easily beat using "fork" and |
|
|
1150 | "exec" (or even "system") in most programs. |
|
|
1151 | |
|
|
1152 | AnyEvent::Filesys::Notify |
|
|
1153 | AnyEvent is good for non-blocking stuff, but it can't detect file or |
|
|
1154 | path changes (e.g. "watch this directory for new files", "watch this |
|
|
1155 | file for changes"). The AnyEvent::Filesys::Notify module promises to |
|
|
1156 | do just that in a portbale fashion, supporting inotify on GNU/Linux |
|
|
1157 | and some weird, without doubt broken, stuff on OS X to monitor |
|
|
1158 | files. It can fall back to blocking scans at regular intervals |
|
|
1159 | transparently on other platforms, so it's about as portable as it |
|
|
1160 | gets. |
|
|
1161 | |
|
|
1162 | (I haven't used it myself, but it seems the biggest problem with it |
|
|
1163 | is it quite bad performance). |
|
|
1164 | |
916 | AnyEvent::HTTPD |
1165 | AnyEvent::DBI |
917 | Provides a simple web application server framework. |
1166 | Executes DBI requests asynchronously in a proxy process for you, |
|
|
1167 | notifying you in an event-based way when the operation is finished. |
918 | |
1168 | |
919 | AnyEvent::FastPing |
1169 | AnyEvent::FastPing |
920 | The fastest ping in the west. |
1170 | The fastest ping in the west. |
921 | |
1171 | |
922 | AnyEvent::DBI |
|
|
923 | Executes DBI requests asynchronously in a proxy process. |
|
|
924 | |
|
|
925 | AnyEvent::AIO |
|
|
926 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
927 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
928 | together. |
|
|
929 | |
|
|
930 | AnyEvent::BDB |
|
|
931 | Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently |
|
|
932 | fuses BDB and AnyEvent together. |
|
|
933 | |
|
|
934 | AnyEvent::GPSD |
|
|
935 | A non-blocking interface to gpsd, a daemon delivering GPS |
|
|
936 | information. |
|
|
937 | |
|
|
938 | AnyEvent::IRC |
|
|
939 | AnyEvent based IRC client module family (replacing the older |
|
|
940 | Net::IRC3). |
|
|
941 | |
|
|
942 | AnyEvent::XMPP |
|
|
943 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
944 | older Net::XMPP2>. |
|
|
945 | |
|
|
946 | AnyEvent::IGS |
|
|
947 | A non-blocking interface to the Internet Go Server protocol (used by |
|
|
948 | App::IGS). |
|
|
949 | |
|
|
950 | Net::FCP |
|
|
951 | AnyEvent-based implementation of the Freenet Client Protocol, |
|
|
952 | birthplace of AnyEvent. |
|
|
953 | |
|
|
954 | Event::ExecFlow |
|
|
955 | High level API for event-based execution flow control. |
|
|
956 | |
|
|
957 | Coro |
1172 | Coro |
958 | Has special support for AnyEvent via Coro::AnyEvent. |
1173 | Has special support for AnyEvent via Coro::AnyEvent, which allows |
|
|
1174 | you to simply invert the flow control - don't call us, we will call |
|
|
1175 | you: |
|
|
1176 | |
|
|
1177 | async { |
|
|
1178 | Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it |
|
|
1179 | print "5 seconds later!\n"; |
|
|
1180 | |
|
|
1181 | Coro::AnyEvent::readable *STDIN; # uses an I/O watcher |
|
|
1182 | my $line = <STDIN>; # works for ttys |
|
|
1183 | |
|
|
1184 | AnyEvent::HTTP::http_get "url", Coro::rouse_cb; |
|
|
1185 | my ($body, $hdr) = Coro::rouse_wait; |
|
|
1186 | }; |
|
|
1187 | |
|
|
1188 | SIMPLIFIED AE API |
|
|
1189 | Starting with version 5.0, AnyEvent officially supports a second, much |
|
|
1190 | simpler, API that is designed to reduce the calling, typing and memory |
|
|
1191 | overhead by using function call syntax and a fixed number of parameters. |
|
|
1192 | |
|
|
1193 | See the AE manpage for details. |
959 | |
1194 | |
960 | ERROR AND EXCEPTION HANDLING |
1195 | ERROR AND EXCEPTION HANDLING |
961 | In general, AnyEvent does not do any error handling - it relies on the |
1196 | In general, AnyEvent does not do any error handling - it relies on the |
962 | caller to do that if required. The AnyEvent::Strict module (see also the |
1197 | caller to do that if required. The AnyEvent::Strict module (see also the |
963 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
1198 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
… | |
… | |
972 | The pure perl event loop simply re-throws the exception (usually within |
1207 | The pure perl event loop simply re-throws the exception (usually within |
973 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
1208 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
974 | Glib uses "install_exception_handler" and so on. |
1209 | Glib uses "install_exception_handler" and so on. |
975 | |
1210 | |
976 | ENVIRONMENT VARIABLES |
1211 | ENVIRONMENT VARIABLES |
977 | The following environment variables are used by this module or its |
1212 | AnyEvent supports a number of environment variables that tune the |
978 | submodules. |
1213 | runtime behaviour. They are usually evaluated when AnyEvent is loaded, |
|
|
1214 | initialised, or a submodule that uses them is loaded. Many of them also |
|
|
1215 | cause AnyEvent to load additional modules - for example, |
|
|
1216 | "PERL_ANYEVENT_DEBUG_WRAP" causes the AnyEvent::Debug module to be |
|
|
1217 | loaded. |
979 | |
1218 | |
980 | Note that AnyEvent will remove *all* environment variables starting with |
1219 | All the environment variables documented here start with |
981 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
1220 | "PERL_ANYEVENT_", which is what AnyEvent considers its own namespace. |
982 | enabled. |
1221 | Other modules are encouraged (but by no means required) to use |
|
|
1222 | "PERL_ANYEVENT_SUBMODULE" if they have registered the |
|
|
1223 | AnyEvent::Submodule namespace on CPAN, for any submodule. For example, |
|
|
1224 | AnyEvent::HTTP could be expected to use "PERL_ANYEVENT_HTTP_PROXY" (it |
|
|
1225 | should not access env variables starting with "AE_", see below). |
|
|
1226 | |
|
|
1227 | All variables can also be set via the "AE_" prefix, that is, instead of |
|
|
1228 | setting "PERL_ANYEVENT_VERBOSE" you can also set "AE_VERBOSE". In case |
|
|
1229 | there is a clash btween anyevent and another program that uses |
|
|
1230 | "AE_something" you can set the corresponding "PERL_ANYEVENT_something" |
|
|
1231 | variable to the empty string, as those variables take precedence. |
|
|
1232 | |
|
|
1233 | When AnyEvent is first loaded, it copies all "AE_xxx" env variables to |
|
|
1234 | their "PERL_ANYEVENT_xxx" counterpart unless that variable already |
|
|
1235 | exists. If taint mode is on, then AnyEvent will remove *all* environment |
|
|
1236 | variables starting with "PERL_ANYEVENT_" from %ENV (or replace them with |
|
|
1237 | "undef" or the empty string, if the corresaponding "AE_" variable is |
|
|
1238 | set). |
|
|
1239 | |
|
|
1240 | The exact algorithm is currently: |
|
|
1241 | |
|
|
1242 | 1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV |
|
|
1243 | 2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists |
|
|
1244 | 3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef. |
|
|
1245 | |
|
|
1246 | This ensures that child processes will not see the "AE_" variables. |
|
|
1247 | |
|
|
1248 | The following environment variables are currently known to AnyEvent: |
983 | |
1249 | |
984 | "PERL_ANYEVENT_VERBOSE" |
1250 | "PERL_ANYEVENT_VERBOSE" |
985 | By default, AnyEvent will be completely silent except in fatal |
1251 | By default, AnyEvent will log messages with loglevel 4 ("error") or |
986 | conditions. You can set this environment variable to make AnyEvent |
1252 | higher (see AnyEvent::Log). You can set this environment variable to |
987 | more talkative. |
1253 | a numerical loglevel to make AnyEvent more (or less) talkative. |
988 | |
1254 | |
|
|
1255 | If you want to do more than just set the global logging level you |
|
|
1256 | should have a look at "PERL_ANYEVENT_LOG", which allows much more |
|
|
1257 | complex specifications. |
|
|
1258 | |
|
|
1259 | When set to 0 ("off"), then no messages whatsoever will be logged |
|
|
1260 | with everything else at defaults. |
|
|
1261 | |
989 | When set to 1 or higher, causes AnyEvent to warn about unexpected |
1262 | When set to 5 or higher ("warn"), AnyEvent warns about unexpected |
990 | conditions, such as not being able to load the event model specified |
1263 | conditions, such as not being able to load the event model specified |
991 | by "PERL_ANYEVENT_MODEL". |
1264 | by "PERL_ANYEVENT_MODEL", or a guard callback throwing an exception |
|
|
1265 | - this is the minimum recommended level for use during development. |
992 | |
1266 | |
993 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
1267 | When set to 7 or higher (info), AnyEvent reports which event model |
994 | event model it chooses. |
1268 | it chooses. |
|
|
1269 | |
|
|
1270 | When set to 8 or higher (debug), then AnyEvent will report extra |
|
|
1271 | information on which optional modules it loads and how it implements |
|
|
1272 | certain features. |
|
|
1273 | |
|
|
1274 | "PERL_ANYEVENT_LOG" |
|
|
1275 | Accepts rather complex logging specifications. For example, you |
|
|
1276 | could log all "debug" messages of some module to stderr, warnings |
|
|
1277 | and above to stderr, and errors and above to syslog, with: |
|
|
1278 | |
|
|
1279 | PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog |
|
|
1280 | |
|
|
1281 | For the rather extensive details, see AnyEvent::Log. |
|
|
1282 | |
|
|
1283 | This variable is evaluated when AnyEvent (or AnyEvent::Log) is |
|
|
1284 | loaded, so will take effect even before AnyEvent has initialised |
|
|
1285 | itself. |
|
|
1286 | |
|
|
1287 | Note that specifying this environment variable causes the |
|
|
1288 | AnyEvent::Log module to be loaded, while "PERL_ANYEVENT_VERBOSE" |
|
|
1289 | does not, so only using the latter saves a few hundred kB of memory |
|
|
1290 | unless a module explicitly needs the extra features of |
|
|
1291 | AnyEvent::Log. |
995 | |
1292 | |
996 | "PERL_ANYEVENT_STRICT" |
1293 | "PERL_ANYEVENT_STRICT" |
997 | AnyEvent does not do much argument checking by default, as thorough |
1294 | AnyEvent does not do much argument checking by default, as thorough |
998 | argument checking is very costly. Setting this variable to a true |
1295 | argument checking is very costly. Setting this variable to a true |
999 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1296 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1000 | thoroughly check the arguments passed to most method calls. If it |
1297 | thoroughly check the arguments passed to most method calls. If it |
1001 | finds any problems, it will croak. |
1298 | finds any problems, it will croak. |
1002 | |
1299 | |
1003 | In other words, enables "strict" mode. |
1300 | In other words, enables "strict" mode. |
1004 | |
1301 | |
1005 | Unlike "use strict", it is definitely recommended to keep it off in |
1302 | Unlike "use strict" (or its modern cousin, "use common::sense", it |
1006 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
1303 | is definitely recommended to keep it off in production. Keeping |
|
|
1304 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1007 | while developing programs can be very useful, however. |
1305 | programs can be very useful, however. |
|
|
1306 | |
|
|
1307 | "PERL_ANYEVENT_DEBUG_SHELL" |
|
|
1308 | If this env variable is nonempty, then its contents will be |
|
|
1309 | interpreted by "AnyEvent::Socket::parse_hostport" and |
|
|
1310 | "AnyEvent::Debug::shell" (after replacing every occurance of $$ by |
|
|
1311 | the process pid). The shell object is saved in |
|
|
1312 | $AnyEvent::Debug::SHELL. |
|
|
1313 | |
|
|
1314 | This happens when the first watcher is created. |
|
|
1315 | |
|
|
1316 | For example, to bind a debug shell on a unix domain socket in |
|
|
1317 | /tmp/debug<pid>.sock, you could use this: |
|
|
1318 | |
|
|
1319 | PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog |
|
|
1320 | # connect with e.g.: socat readline /tmp/debug123.sock |
|
|
1321 | |
|
|
1322 | Or to bind to tcp port 4545 on localhost: |
|
|
1323 | |
|
|
1324 | PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog |
|
|
1325 | # connect with e.g.: telnet localhost 4545 |
|
|
1326 | |
|
|
1327 | Note that creating sockets in /tmp or on localhost is very unsafe on |
|
|
1328 | multiuser systems. |
|
|
1329 | |
|
|
1330 | "PERL_ANYEVENT_DEBUG_WRAP" |
|
|
1331 | Can be set to 0, 1 or 2 and enables wrapping of all watchers for |
|
|
1332 | debugging purposes. See "AnyEvent::Debug::wrap" for details. |
1008 | |
1333 | |
1009 | "PERL_ANYEVENT_MODEL" |
1334 | "PERL_ANYEVENT_MODEL" |
1010 | This can be used to specify the event model to be used by AnyEvent, |
1335 | This can be used to specify the event model to be used by AnyEvent, |
1011 | before auto detection and -probing kicks in. It must be a string |
1336 | before auto detection and -probing kicks in. |
1012 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1337 | |
1013 | gets prepended and the resulting module name is loaded and if the |
1338 | It normally is a string consisting entirely of ASCII letters (e.g. |
1014 | load was successful, used as event model. If it fails to load |
1339 | "EV" or "IOAsync"). The string "AnyEvent::Impl::" gets prepended and |
|
|
1340 | the resulting module name is loaded and - if the load was successful |
|
|
1341 | - used as event model backend. If it fails to load then AnyEvent |
1015 | AnyEvent will proceed with auto detection and -probing. |
1342 | will proceed with auto detection and -probing. |
1016 | |
1343 | |
1017 | This functionality might change in future versions. |
1344 | If the string ends with "::" instead (e.g. "AnyEvent::Impl::EV::") |
|
|
1345 | then nothing gets prepended and the module name is used as-is (hint: |
|
|
1346 | "::" at the end of a string designates a module name and quotes it |
|
|
1347 | appropriately). |
1018 | |
1348 | |
1019 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
1349 | For example, to force the pure perl model (AnyEvent::Loop::Perl) you |
1020 | could start your program like this: |
1350 | could start your program like this: |
1021 | |
1351 | |
1022 | PERL_ANYEVENT_MODEL=Perl perl ... |
1352 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1353 | |
|
|
1354 | "PERL_ANYEVENT_IO_MODEL" |
|
|
1355 | The current file I/O model - see AnyEvent::IO for more info. |
|
|
1356 | |
|
|
1357 | At the moment, only "Perl" (small, pure-perl, synchronous) and |
|
|
1358 | "IOAIO" (truly asynchronous) are supported. The default is "IOAIO" |
|
|
1359 | if AnyEvent::AIO can be loaded, otherwise it is "Perl". |
1023 | |
1360 | |
1024 | "PERL_ANYEVENT_PROTOCOLS" |
1361 | "PERL_ANYEVENT_PROTOCOLS" |
1025 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
1362 | Used by both AnyEvent::DNS and AnyEvent::Socket to determine |
1026 | preferences for IPv4 or IPv6. The default is unspecified (and might |
1363 | preferences for IPv4 or IPv6. The default is unspecified (and might |
1027 | change, or be the result of auto probing). |
1364 | change, or be the result of auto probing). |
… | |
… | |
1031 | mentioned will be used, and preference will be given to protocols |
1368 | mentioned will be used, and preference will be given to protocols |
1032 | mentioned earlier in the list. |
1369 | mentioned earlier in the list. |
1033 | |
1370 | |
1034 | This variable can effectively be used for denial-of-service attacks |
1371 | This variable can effectively be used for denial-of-service attacks |
1035 | against local programs (e.g. when setuid), although the impact is |
1372 | against local programs (e.g. when setuid), although the impact is |
1036 | likely small, as the program has to handle conenction and other |
1373 | likely small, as the program has to handle connection and other |
1037 | failures anyways. |
1374 | failures anyways. |
1038 | |
1375 | |
1039 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
1376 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
1040 | IPv6, but support both and try to use both. |
1377 | IPv6, but support both and try to use both. |
1041 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1378 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1042 | resolve or contact IPv6 addresses. |
1379 | resolve or contact IPv6 addresses. |
1043 | "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but |
1380 | "PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but |
1044 | prefer IPv6 over IPv4. |
1381 | prefer IPv6 over IPv4. |
1045 | |
1382 | |
|
|
1383 | "PERL_ANYEVENT_HOSTS" |
|
|
1384 | This variable, if specified, overrides the /etc/hosts file used by |
|
|
1385 | AnyEvent::Socket"::resolve_sockaddr", i.e. hosts aliases will be |
|
|
1386 | read from that file instead. |
|
|
1387 | |
1046 | "PERL_ANYEVENT_EDNS0" |
1388 | "PERL_ANYEVENT_EDNS0" |
1047 | Used by AnyEvent::DNS to decide whether to use the EDNS0 extension |
1389 | Used by AnyEvent::DNS to decide whether to use the EDNS0 extension |
1048 | for DNS. This extension is generally useful to reduce DNS traffic, |
1390 | for DNS. This extension is generally useful to reduce DNS traffic, |
1049 | but some (broken) firewalls drop such DNS packets, which is why it |
1391 | especially when DNSSEC is involved, but some (broken) firewalls drop |
1050 | is off by default. |
1392 | such DNS packets, which is why it is off by default. |
1051 | |
1393 | |
1052 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
1394 | Setting this variable to 1 will cause AnyEvent::DNS to announce |
1053 | EDNS0 in its DNS requests. |
1395 | EDNS0 in its DNS requests. |
1054 | |
1396 | |
1055 | "PERL_ANYEVENT_MAX_FORKS" |
1397 | "PERL_ANYEVENT_MAX_FORKS" |
… | |
… | |
1059 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
1401 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
1060 | The default value for the "max_outstanding" parameter for the |
1402 | The default value for the "max_outstanding" parameter for the |
1061 | default DNS resolver - this is the maximum number of parallel DNS |
1403 | default DNS resolver - this is the maximum number of parallel DNS |
1062 | requests that are sent to the DNS server. |
1404 | requests that are sent to the DNS server. |
1063 | |
1405 | |
|
|
1406 | "PERL_ANYEVENT_MAX_SIGNAL_LATENCY" |
|
|
1407 | Perl has inherently racy signal handling (you can basically choose |
|
|
1408 | between losing signals and memory corruption) - pure perl event |
|
|
1409 | loops (including "AnyEvent::Loop", when "Async::Interrupt" isn't |
|
|
1410 | available) therefore have to poll regularly to avoid losing signals. |
|
|
1411 | |
|
|
1412 | Some event loops are racy, but don't poll regularly, and some event |
|
|
1413 | loops are written in C but are still racy. For those event loops, |
|
|
1414 | AnyEvent installs a timer that regularly wakes up the event loop. |
|
|
1415 | |
|
|
1416 | By default, the interval for this timer is 10 seconds, but you can |
|
|
1417 | override this delay with this environment variable (or by setting |
|
|
1418 | the $AnyEvent::MAX_SIGNAL_LATENCY variable before creating signal |
|
|
1419 | watchers). |
|
|
1420 | |
|
|
1421 | Lower values increase CPU (and energy) usage, higher values can |
|
|
1422 | introduce long delays when reaping children or waiting for signals. |
|
|
1423 | |
|
|
1424 | The AnyEvent::Async module, if available, will be used to avoid this |
|
|
1425 | polling (with most event loops). |
|
|
1426 | |
1064 | "PERL_ANYEVENT_RESOLV_CONF" |
1427 | "PERL_ANYEVENT_RESOLV_CONF" |
1065 | The file to use instead of /etc/resolv.conf (or OS-specific |
1428 | The absolute path to a resolv.conf-style file to use instead of |
1066 | configuration) in the default resolver. When set to the empty |
1429 | /etc/resolv.conf (or the OS-specific configuration) in the default |
1067 | string, no default config will be used. |
1430 | resolver, or the empty string to select the default configuration. |
1068 | |
1431 | |
1069 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
1432 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
1070 | When neither "ca_file" nor "ca_path" was specified during |
1433 | When neither "ca_file" nor "ca_path" was specified during |
1071 | AnyEvent::TLS context creation, and either of these environment |
1434 | AnyEvent::TLS context creation, and either of these environment |
1072 | variables exist, they will be used to specify CA certificate |
1435 | variables are nonempty, they will be used to specify CA certificate |
1073 | locations instead of a system-dependent default. |
1436 | locations instead of a system-dependent default. |
|
|
1437 | |
|
|
1438 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
|
|
1439 | When these are set to 1, then the respective modules are not loaded. |
|
|
1440 | Mostly good for testing AnyEvent itself. |
1074 | |
1441 | |
1075 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1442 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1076 | This is an advanced topic that you do not normally need to use AnyEvent |
1443 | This is an advanced topic that you do not normally need to use AnyEvent |
1077 | in a module. This section is only of use to event loop authors who want |
1444 | in a module. This section is only of use to event loop authors who want |
1078 | to provide AnyEvent compatibility. |
1445 | to provide AnyEvent compatibility. |
… | |
… | |
1133 | warn "read: $input\n"; # output what has been read |
1500 | warn "read: $input\n"; # output what has been read |
1134 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
1501 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
1135 | }, |
1502 | }, |
1136 | ); |
1503 | ); |
1137 | |
1504 | |
1138 | my $time_watcher; # can only be used once |
|
|
1139 | |
|
|
1140 | sub new_timer { |
|
|
1141 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1505 | my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub { |
1142 | warn "timeout\n"; # print 'timeout' about every second |
1506 | warn "timeout\n"; # print 'timeout' at most every second |
1143 | &new_timer; # and restart the time |
|
|
1144 | }); |
|
|
1145 | } |
1507 | }); |
1146 | |
|
|
1147 | new_timer; # create first timer |
|
|
1148 | |
1508 | |
1149 | $cv->recv; # wait until user enters /^q/i |
1509 | $cv->recv; # wait until user enters /^q/i |
1150 | |
1510 | |
1151 | REAL-WORLD EXAMPLE |
1511 | REAL-WORLD EXAMPLE |
1152 | Consider the Net::FCP module. It features (among others) the following |
1512 | Consider the Net::FCP module. It features (among others) the following |
… | |
… | |
1224 | |
1584 | |
1225 | The actual code goes further and collects all errors ("die"s, |
1585 | The actual code goes further and collects all errors ("die"s, |
1226 | exceptions) that occurred during request processing. The "result" method |
1586 | exceptions) that occurred during request processing. The "result" method |
1227 | detects whether an exception as thrown (it is stored inside the $txn |
1587 | detects whether an exception as thrown (it is stored inside the $txn |
1228 | object) and just throws the exception, which means connection errors and |
1588 | object) and just throws the exception, which means connection errors and |
1229 | other problems get reported tot he code that tries to use the result, |
1589 | other problems get reported to the code that tries to use the result, |
1230 | not in a random callback. |
1590 | not in a random callback. |
1231 | |
1591 | |
1232 | All of this enables the following usage styles: |
1592 | All of this enables the following usage styles: |
1233 | |
1593 | |
1234 | 1. Blocking: |
1594 | 1. Blocking: |
… | |
… | |
1252 | my $txn = shift; |
1612 | my $txn = shift; |
1253 | my $data = $txn->result; |
1613 | my $data = $txn->result; |
1254 | ... |
1614 | ... |
1255 | }); |
1615 | }); |
1256 | |
1616 | |
1257 | EV::loop; |
1617 | EV::run; |
1258 | |
1618 | |
1259 | 3b. The module user could use AnyEvent, too: |
1619 | 3b. The module user could use AnyEvent, too: |
1260 | |
1620 | |
1261 | use AnyEvent; |
1621 | use AnyEvent; |
1262 | |
1622 | |
… | |
… | |
1279 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1639 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1280 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1640 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1281 | which it is), lets them fire exactly once and destroys them again. |
1641 | which it is), lets them fire exactly once and destroys them again. |
1282 | |
1642 | |
1283 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1643 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1284 | distribution. |
1644 | distribution. It uses the AE interface, which makes a real difference |
|
|
1645 | for the EV and Perl backends only. |
1285 | |
1646 | |
1286 | Explanation of the columns |
1647 | Explanation of the columns |
1287 | *watcher* is the number of event watchers created/destroyed. Since |
1648 | *watcher* is the number of event watchers created/destroyed. Since |
1288 | different event models feature vastly different performances, each event |
1649 | different event models feature vastly different performances, each event |
1289 | loop was given a number of watchers so that overall runtime is |
1650 | loop was given a number of watchers so that overall runtime is |
… | |
… | |
1308 | *destroy* is the time, in microseconds, that it takes to destroy a |
1669 | *destroy* is the time, in microseconds, that it takes to destroy a |
1309 | single watcher. |
1670 | single watcher. |
1310 | |
1671 | |
1311 | Results |
1672 | Results |
1312 | name watchers bytes create invoke destroy comment |
1673 | name watchers bytes create invoke destroy comment |
1313 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
1674 | EV/EV 100000 223 0.47 0.43 0.27 EV native interface |
1314 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1675 | EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers |
1315 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1676 | Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal |
1316 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1677 | Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation |
1317 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1678 | Event/Event 16000 516 31.16 31.84 0.82 Event native interface |
1318 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1679 | Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers |
1319 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
1680 | IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll |
1320 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
1681 | IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll |
1321 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1682 | Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour |
1322 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1683 | Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers |
1323 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1684 | POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event |
1324 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1685 | POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select |
1325 | |
1686 | |
1326 | Discussion |
1687 | Discussion |
1327 | The benchmark does *not* measure scalability of the event loop very |
1688 | The benchmark does *not* measure scalability of the event loop very |
1328 | well. For example, a select-based event loop (such as the pure perl one) |
1689 | well. For example, a select-based event loop (such as the pure perl one) |
1329 | can never compete with an event loop that uses epoll when the number of |
1690 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1340 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1701 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1341 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
1702 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
1342 | CPU cycles with POE. |
1703 | CPU cycles with POE. |
1343 | |
1704 | |
1344 | "EV" is the sole leader regarding speed and memory use, which are both |
1705 | "EV" is the sole leader regarding speed and memory use, which are both |
1345 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
1706 | maximal/minimal, respectively. When using the AE API there is zero |
|
|
1707 | overhead (when going through the AnyEvent API create is about 5-6 times |
|
|
1708 | slower, with other times being equal, so still uses far less memory than |
1346 | far less memory than any other event loop and is still faster than Event |
1709 | any other event loop and is still faster than Event natively). |
1347 | natively. |
|
|
1348 | |
1710 | |
1349 | The pure perl implementation is hit in a few sweet spots (both the |
1711 | The pure perl implementation is hit in a few sweet spots (both the |
1350 | constant timeout and the use of a single fd hit optimisations in the |
1712 | constant timeout and the use of a single fd hit optimisations in the |
1351 | perl interpreter and the backend itself). Nevertheless this shows that |
1713 | perl interpreter and the backend itself). Nevertheless this shows that |
1352 | it adds very little overhead in itself. Like any select-based backend |
1714 | it adds very little overhead in itself. Like any select-based backend |
… | |
… | |
1398 | when used without AnyEvent), but most event loops have acceptable |
1760 | when used without AnyEvent), but most event loops have acceptable |
1399 | performance with or without AnyEvent. |
1761 | performance with or without AnyEvent. |
1400 | |
1762 | |
1401 | * The overhead AnyEvent adds is usually much smaller than the overhead |
1763 | * The overhead AnyEvent adds is usually much smaller than the overhead |
1402 | of the actual event loop, only with extremely fast event loops such |
1764 | of the actual event loop, only with extremely fast event loops such |
1403 | as EV adds AnyEvent significant overhead. |
1765 | as EV does AnyEvent add significant overhead. |
1404 | |
1766 | |
1405 | * You should avoid POE like the plague if you want performance or |
1767 | * You should avoid POE like the plague if you want performance or |
1406 | reasonable memory usage. |
1768 | reasonable memory usage. |
1407 | |
1769 | |
1408 | BENCHMARKING THE LARGE SERVER CASE |
1770 | BENCHMARKING THE LARGE SERVER CASE |
… | |
… | |
1422 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1784 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1423 | 100 (1%) are active. This mirrors the activity of large servers with |
1785 | 100 (1%) are active. This mirrors the activity of large servers with |
1424 | many connections, most of which are idle at any one point in time. |
1786 | many connections, most of which are idle at any one point in time. |
1425 | |
1787 | |
1426 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1788 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1427 | distribution. |
1789 | distribution. It uses the AE interface, which makes a real difference |
|
|
1790 | for the EV and Perl backends only. |
1428 | |
1791 | |
1429 | Explanation of the columns |
1792 | Explanation of the columns |
1430 | *sockets* is the number of sockets, and twice the number of "servers" |
1793 | *sockets* is the number of sockets, and twice the number of "servers" |
1431 | (as each server has a read and write socket end). |
1794 | (as each server has a read and write socket end). |
1432 | |
1795 | |
… | |
… | |
1438 | forwarding it to another server. This includes deleting the old timeout |
1801 | forwarding it to another server. This includes deleting the old timeout |
1439 | and creating a new one that moves the timeout into the future. |
1802 | and creating a new one that moves the timeout into the future. |
1440 | |
1803 | |
1441 | Results |
1804 | Results |
1442 | name sockets create request |
1805 | name sockets create request |
1443 | EV 20000 69.01 11.16 |
1806 | EV 20000 62.66 7.99 |
1444 | Perl 20000 73.32 35.87 |
1807 | Perl 20000 68.32 32.64 |
1445 | IOAsync 20000 157.00 98.14 epoll |
1808 | IOAsync 20000 174.06 101.15 epoll |
1446 | IOAsync 20000 159.31 616.06 poll |
1809 | IOAsync 20000 174.67 610.84 poll |
1447 | Event 20000 212.62 257.32 |
1810 | Event 20000 202.69 242.91 |
1448 | Glib 20000 651.16 1896.30 |
1811 | Glib 20000 557.01 1689.52 |
1449 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1812 | POE 20000 341.54 12086.32 uses POE::Loop::Event |
1450 | |
1813 | |
1451 | Discussion |
1814 | Discussion |
1452 | This benchmark *does* measure scalability and overall performance of the |
1815 | This benchmark *does* measure scalability and overall performance of the |
1453 | particular event loop. |
1816 | particular event loop. |
1454 | |
1817 | |
… | |
… | |
1567 | As you can see, the AnyEvent + EV combination even beats the |
1930 | As you can see, the AnyEvent + EV combination even beats the |
1568 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
1931 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
1569 | backend easily beats IO::Lambda and POE. |
1932 | backend easily beats IO::Lambda and POE. |
1570 | |
1933 | |
1571 | And even the 100% non-blocking version written using the high-level (and |
1934 | And even the 100% non-blocking version written using the high-level (and |
1572 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
1935 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda |
1573 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
1936 | higher level ("unoptimised") abstractions by a large margin, even though |
1574 | in a non-blocking way. |
1937 | it does all of DNS, tcp-connect and socket I/O in a non-blocking way. |
1575 | |
1938 | |
1576 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
1939 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
1577 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
1940 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
1578 | part of the IO::lambda distribution and were used without any changes. |
1941 | part of the IO::Lambda distribution and were used without any changes. |
1579 | |
1942 | |
1580 | SIGNALS |
1943 | SIGNALS |
1581 | AnyEvent currently installs handlers for these signals: |
1944 | AnyEvent currently installs handlers for these signals: |
1582 | |
1945 | |
1583 | SIGCHLD |
1946 | SIGCHLD |
… | |
… | |
1603 | it is that this way, the handler will be restored to defaults on |
1966 | it is that this way, the handler will be restored to defaults on |
1604 | exec. |
1967 | exec. |
1605 | |
1968 | |
1606 | Feel free to install your own handler, or reset it to defaults. |
1969 | Feel free to install your own handler, or reset it to defaults. |
1607 | |
1970 | |
|
|
1971 | RECOMMENDED/OPTIONAL MODULES |
|
|
1972 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
|
|
1973 | its built-in modules) are required to use it. |
|
|
1974 | |
|
|
1975 | That does not mean that AnyEvent won't take advantage of some additional |
|
|
1976 | modules if they are installed. |
|
|
1977 | |
|
|
1978 | This section explains which additional modules will be used, and how |
|
|
1979 | they affect AnyEvent's operation. |
|
|
1980 | |
|
|
1981 | Async::Interrupt |
|
|
1982 | This slightly arcane module is used to implement fast signal |
|
|
1983 | handling: To my knowledge, there is no way to do completely |
|
|
1984 | race-free and quick signal handling in pure perl. To ensure that |
|
|
1985 | signals still get delivered, AnyEvent will start an interval timer |
|
|
1986 | to wake up perl (and catch the signals) with some delay (default is |
|
|
1987 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1988 | |
|
|
1989 | If this module is available, then it will be used to implement |
|
|
1990 | signal catching, which means that signals will not be delayed, and |
|
|
1991 | the event loop will not be interrupted regularly, which is more |
|
|
1992 | efficient (and good for battery life on laptops). |
|
|
1993 | |
|
|
1994 | This affects not just the pure-perl event loop, but also other event |
|
|
1995 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
|
|
1996 | |
|
|
1997 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
|
|
1998 | natively, and either employ their own workarounds (POE) or use |
|
|
1999 | AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
2000 | Installing Async::Interrupt does nothing for those backends. |
|
|
2001 | |
|
|
2002 | EV This module isn't really "optional", as it is simply one of the |
|
|
2003 | backend event loops that AnyEvent can use. However, it is simply the |
|
|
2004 | best event loop available in terms of features, speed and stability: |
|
|
2005 | It supports the AnyEvent API optimally, implements all the watcher |
|
|
2006 | types in XS, does automatic timer adjustments even when no monotonic |
|
|
2007 | clock is available, can take avdantage of advanced kernel interfaces |
|
|
2008 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
|
|
2009 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
|
|
2010 | Glib::EV). |
|
|
2011 | |
|
|
2012 | If you only use backends that rely on another event loop (e.g. |
|
|
2013 | "Tk"), then this module will do nothing for you. |
|
|
2014 | |
|
|
2015 | Guard |
|
|
2016 | The guard module, when used, will be used to implement |
|
|
2017 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
|
|
2018 | uses a lot less memory), but otherwise doesn't affect guard |
|
|
2019 | operation much. It is purely used for performance. |
|
|
2020 | |
|
|
2021 | JSON and JSON::XS |
|
|
2022 | One of these modules is required when you want to read or write JSON |
|
|
2023 | data via AnyEvent::Handle. JSON is also written in pure-perl, but |
|
|
2024 | can take advantage of the ultra-high-speed JSON::XS module when it |
|
|
2025 | is installed. |
|
|
2026 | |
|
|
2027 | Net::SSLeay |
|
|
2028 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
|
|
2029 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
|
|
2030 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
|
|
2031 | |
|
|
2032 | Time::HiRes |
|
|
2033 | This module is part of perl since release 5.008. It will be used |
|
|
2034 | when the chosen event library does not come with a timing source of |
|
|
2035 | its own. The pure-perl event loop (AnyEvent::Loop) will additionally |
|
|
2036 | load it to try to use a monotonic clock for timing stability. |
|
|
2037 | |
|
|
2038 | AnyEvent::AIO (and IO::AIO) |
|
|
2039 | The default implementation of AnyEvent::IO is to do I/O |
|
|
2040 | synchronously, stopping programs while they access the disk, which |
|
|
2041 | is fine for a lot of programs. |
|
|
2042 | |
|
|
2043 | Installing AnyEvent::AIO (and its IO::AIO dependency) makes it |
|
|
2044 | switch to a true asynchronous implementation, so event processing |
|
|
2045 | can continue even while waiting for disk I/O. |
|
|
2046 | |
1608 | FORK |
2047 | FORK |
1609 | Most event libraries are not fork-safe. The ones who are usually are |
2048 | Most event libraries are not fork-safe. The ones who are usually are |
1610 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
2049 | because they rely on inefficient but fork-safe "select" or "poll" calls |
1611 | Only EV is fully fork-aware. |
2050 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
|
|
2051 | epoll are usually badly thought-out hacks that are incompatible with |
|
|
2052 | fork in one way or another. Only EV is fully fork-aware and ensures that |
|
|
2053 | you continue event-processing in both parent and child (or both, if you |
|
|
2054 | know what you are doing). |
|
|
2055 | |
|
|
2056 | This means that, in general, you cannot fork and do event processing in |
|
|
2057 | the child if the event library was initialised before the fork (which |
|
|
2058 | usually happens when the first AnyEvent watcher is created, or the |
|
|
2059 | library is loaded). |
1612 | |
2060 | |
1613 | If you have to fork, you must either do so *before* creating your first |
2061 | If you have to fork, you must either do so *before* creating your first |
1614 | watcher OR you must not use AnyEvent at all in the child. |
2062 | watcher OR you must not use AnyEvent at all in the child OR you must do |
|
|
2063 | something completely out of the scope of AnyEvent (see below). |
|
|
2064 | |
|
|
2065 | The problem of doing event processing in the parent *and* the child is |
|
|
2066 | much more complicated: even for backends that *are* fork-aware or |
|
|
2067 | fork-safe, their behaviour is not usually what you want: fork clones all |
|
|
2068 | watchers, that means all timers, I/O watchers etc. are active in both |
|
|
2069 | parent and child, which is almost never what you want. Using "exec" to |
|
|
2070 | start worker children from some kind of manage prrocess is usually |
|
|
2071 | preferred, because it is much easier and cleaner, at the expense of |
|
|
2072 | having to have another binary. |
|
|
2073 | |
|
|
2074 | In addition to logical problems with fork, there are also implementation |
|
|
2075 | problems. For example, on POSIX systems, you cannot fork at all in Perl |
|
|
2076 | code if a thread (I am talking of pthreads here) was ever created in the |
|
|
2077 | process, and this is just the tip of the iceberg. In general, using fork |
|
|
2078 | from Perl is difficult, and attempting to use fork without an exec to |
|
|
2079 | implement some kind of parallel processing is almost certainly doomed. |
|
|
2080 | |
|
|
2081 | To safely fork and exec, you should use a module such as Proc::FastSpawn |
|
|
2082 | that let's you safely fork and exec new processes. |
|
|
2083 | |
|
|
2084 | If you want to do multiprocessing using processes, you can look at the |
|
|
2085 | AnyEvent::Fork module (and some related modules such as |
|
|
2086 | AnyEvent::Fork::RPC, AnyEvent::Fork::Pool and AnyEvent::Fork::Remote). |
|
|
2087 | This module allows you to safely create subprocesses without any |
|
|
2088 | limitations - you can use X11 toolkits or AnyEvent in the children |
|
|
2089 | created by AnyEvent::Fork safely and without any special precautions. |
1615 | |
2090 | |
1616 | SECURITY CONSIDERATIONS |
2091 | SECURITY CONSIDERATIONS |
1617 | AnyEvent can be forced to load any event model via |
2092 | AnyEvent can be forced to load any event model via |
1618 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
2093 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1619 | to execute arbitrary code or directly gain access, it can easily be used |
2094 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1643 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
2118 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1644 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
2119 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1645 | not as pronounced). |
2120 | not as pronounced). |
1646 | |
2121 | |
1647 | SEE ALSO |
2122 | SEE ALSO |
1648 | Utility functions: AnyEvent::Util. |
2123 | Tutorial/Introduction: AnyEvent::Intro. |
1649 | |
2124 | |
1650 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
2125 | FAQ: AnyEvent::FAQ. |
1651 | Event::Lib, Qt, POE. |
2126 | |
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2127 | Utility functions: AnyEvent::Util (misc. grab-bag), AnyEvent::Log |
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2128 | (simply logging). |
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2129 | |
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2130 | Development/Debugging: AnyEvent::Strict (stricter checking), |
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2131 | AnyEvent::Debug (interactive shell, watcher tracing). |
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2132 | |
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2133 | Supported event modules: AnyEvent::Loop, EV, EV::Glib, Glib::EV, Event, |
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2134 | Glib::Event, Glib, Tk, Event::Lib, Qt, POE, FLTK, Cocoa::EventLoop, UV. |
1652 | |
2135 | |
1653 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
2136 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1654 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
2137 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1655 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
2138 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
1656 | AnyEvent::Impl::IOAsync. |
2139 | AnyEvent::Impl::IOAsync, AnyEvent::Impl::Irssi, AnyEvent::Impl::FLTK, |
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2140 | AnyEvent::Impl::Cocoa, AnyEvent::Impl::UV. |
1657 | |
2141 | |
1658 | Non-blocking file handles, sockets, TCP clients and servers: |
2142 | Non-blocking handles, pipes, stream sockets, TCP clients and servers: |
1659 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
2143 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1660 | |
2144 | |
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2145 | Asynchronous File I/O: AnyEvent::IO. |
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2146 | |
1661 | Asynchronous DNS: AnyEvent::DNS. |
2147 | Asynchronous DNS: AnyEvent::DNS. |
1662 | |
2148 | |
1663 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
2149 | Thread support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event. |
1664 | |
2150 | |
1665 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
2151 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::IRC, |
1666 | AnyEvent::HTTP. |
2152 | AnyEvent::HTTP. |
1667 | |
2153 | |
1668 | AUTHOR |
2154 | AUTHOR |
1669 | Marc Lehmann <schmorp@schmorp.de> |
2155 | Marc Lehmann <schmorp@schmorp.de> |
1670 | http://home.schmorp.de/ |
2156 | http://anyevent.schmorp.de |
1671 | |
2157 | |