1 | =head1 NAME |
1 | =head1 => NAME |
2 | |
2 | |
3 | AnyEvent - provide framework for multiple event loops |
3 | AnyEvent - provide framework for multiple event loops |
4 | |
4 | |
5 | Event, Coro, Glib, Tk, Perl - various supported event loops |
5 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops |
6 | |
6 | |
7 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
8 | |
8 | |
9 | use AnyEvent; |
9 | use AnyEvent; |
10 | |
10 | |
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14 | |
14 | |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
16 | ... |
16 | ... |
17 | }); |
17 | }); |
18 | |
18 | |
19 | my $w = AnyEvent->condvar; # stores wether a condition was flagged |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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20 | $w->send; # wake up current and all future recv's |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
21 | $w->recv; # enters "main loop" till $condvar gets ->send |
21 | $w->broadcast; # wake up current and all future wait's |
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22 | |
22 | |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
24 | |
24 | |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
26 | nowadays. So what is different about AnyEvent? |
26 | nowadays. So what is different about AnyEvent? |
… | |
… | |
29 | policy> and AnyEvent is I<small and efficient>. |
29 | policy> and AnyEvent is I<small and efficient>. |
30 | |
30 | |
31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
32 | interfaces to whatever event model the main program happens to use in a |
32 | interfaces to whatever event model the main program happens to use in a |
33 | pragmatic way. For event models and certain classes of immortals alike, |
33 | pragmatic way. For event models and certain classes of immortals alike, |
34 | the statement "there can only be one" is a bitter reality, and AnyEvent |
34 | the statement "there can only be one" is a bitter reality: In general, |
35 | helps hiding the differences. |
35 | only one event loop can be active at the same time in a process. AnyEvent |
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36 | helps hiding the differences between those event loops. |
36 | |
37 | |
37 | The goal of AnyEvent is to offer module authors the ability to do event |
38 | The goal of AnyEvent is to offer module authors the ability to do event |
38 | programming (waiting for I/O or timer events) without subscribing to a |
39 | programming (waiting for I/O or timer events) without subscribing to a |
39 | religion, a way of living, and most importantly: without forcing your |
40 | religion, a way of living, and most importantly: without forcing your |
40 | module users into the same thing by forcing them to use the same event |
41 | module users into the same thing by forcing them to use the same event |
41 | model you use. |
42 | model you use. |
42 | |
43 | |
43 | For modules like POE or IO::Async (which is actually doing all I/O |
44 | For modules like POE or IO::Async (which is a total misnomer as it is |
44 | I<synchronously>...), using them in your module is like joining a |
45 | actually doing all I/O I<synchronously>...), using them in your module is |
45 | cult: After you joined, you are dependent on them and you cannot use |
46 | like joining a cult: After you joined, you are dependent on them and you |
46 | anything else, as it is simply incompatible to everything that isn't |
47 | cannot use anything else, as it is simply incompatible to everything that |
47 | itself. |
48 | isn't itself. What's worse, all the potential users of your module are |
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49 | I<also> forced to use the same event loop you use. |
48 | |
50 | |
49 | AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk |
51 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
50 | works fine etc. etc. but none of these work together with the rest: POE |
52 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
51 | + IO::Async? no go. Tk + Event? no go. If your module uses one of |
53 | with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if |
52 | those, every user of your module has to use it, too. If your module |
54 | your module uses one of those, every user of your module has to use it, |
53 | uses AnyEvent, it works transparently with all event models it supports |
55 | too. But if your module uses AnyEvent, it works transparently with all |
54 | (including stuff like POE and IO::Async). |
56 | event models it supports (including stuff like POE and IO::Async, as long |
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57 | as those use one of the supported event loops. It is trivial to add new |
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58 | event loops to AnyEvent, too, so it is future-proof). |
55 | |
59 | |
56 | In addition of being free of having to use I<the one and only true event |
60 | In addition to being free of having to use I<the one and only true event |
57 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
61 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
58 | modules, you get an enourmous amount of code and strict rules you have |
62 | modules, you get an enormous amount of code and strict rules you have to |
59 | to follow. AnyEvent, on the other hand, is lean and to the point by only |
63 | follow. AnyEvent, on the other hand, is lean and up to the point, by only |
60 | offering the functionality that is useful, in as thin as a wrapper as |
64 | offering the functionality that is necessary, in as thin as a wrapper as |
61 | technically possible. |
65 | technically possible. |
62 | |
66 | |
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67 | Of course, AnyEvent comes with a big (and fully optional!) toolbox |
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68 | of useful functionality, such as an asynchronous DNS resolver, 100% |
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69 | non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms |
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70 | such as Windows) and lots of real-world knowledge and workarounds for |
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71 | platform bugs and differences. |
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72 | |
63 | Of course, if you want lots of policy (this can arguably be somewhat |
73 | Now, if you I<do want> lots of policy (this can arguably be somewhat |
64 | useful) and you want to force your users to use the one and only event |
74 | useful) and you want to force your users to use the one and only event |
65 | model, you should I<not> use this module. |
75 | model, you should I<not> use this module. |
66 | |
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67 | |
76 | |
68 | =head1 DESCRIPTION |
77 | =head1 DESCRIPTION |
69 | |
78 | |
70 | L<AnyEvent> provides an identical interface to multiple event loops. This |
79 | L<AnyEvent> provides an identical interface to multiple event loops. This |
71 | allows module authors to utilise an event loop without forcing module |
80 | allows module authors to utilise an event loop without forcing module |
72 | users to use the same event loop (as only a single event loop can coexist |
81 | users to use the same event loop (as only a single event loop can coexist |
73 | peacefully at any one time). |
82 | peacefully at any one time). |
74 | |
83 | |
75 | The interface itself is vaguely similar but not identical to the Event |
84 | The interface itself is vaguely similar, but not identical to the L<Event> |
76 | module. |
85 | module. |
77 | |
86 | |
78 | On the first call of any method, the module tries to detect the currently |
87 | During the first call of any watcher-creation method, the module tries |
79 | loaded event loop by probing wether any of the following modules is |
88 | to detect the currently loaded event loop by probing whether one of the |
80 | loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is |
89 | following modules is already loaded: L<EV>, |
81 | used. If none is found, the module tries to load these modules in the |
90 | L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, |
82 | order given. The first one that could be successfully loaded will be |
91 | L<POE>. The first one found is used. If none are found, the module tries |
83 | used. If still none could be found, AnyEvent will fall back to a pure-perl |
92 | to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl |
84 | event loop, which is also not very efficient. |
93 | adaptor should always succeed) in the order given. The first one that can |
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94 | be successfully loaded will be used. If, after this, still none could be |
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95 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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96 | very efficient, but should work everywhere. |
85 | |
97 | |
86 | Because AnyEvent first checks for modules that are already loaded, loading |
98 | Because AnyEvent first checks for modules that are already loaded, loading |
87 | an Event model explicitly before first using AnyEvent will likely make |
99 | an event model explicitly before first using AnyEvent will likely make |
88 | that model the default. For example: |
100 | that model the default. For example: |
89 | |
101 | |
90 | use Tk; |
102 | use Tk; |
91 | use AnyEvent; |
103 | use AnyEvent; |
92 | |
104 | |
93 | # .. AnyEvent will likely default to Tk |
105 | # .. AnyEvent will likely default to Tk |
94 | |
106 | |
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107 | The I<likely> means that, if any module loads another event model and |
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108 | starts using it, all bets are off. Maybe you should tell their authors to |
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109 | use AnyEvent so their modules work together with others seamlessly... |
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110 | |
95 | The pure-perl implementation of AnyEvent is called |
111 | The pure-perl implementation of AnyEvent is called |
96 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
112 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
97 | explicitly. |
113 | explicitly and enjoy the high availability of that event loop :) |
98 | |
114 | |
99 | =head1 WATCHERS |
115 | =head1 WATCHERS |
100 | |
116 | |
101 | AnyEvent has the central concept of a I<watcher>, which is an object that |
117 | AnyEvent has the central concept of a I<watcher>, which is an object that |
102 | stores relevant data for each kind of event you are waiting for, such as |
118 | stores relevant data for each kind of event you are waiting for, such as |
103 | the callback to call, the filehandle to watch, etc. |
119 | the callback to call, the file handle to watch, etc. |
104 | |
120 | |
105 | These watchers are normal Perl objects with normal Perl lifetime. After |
121 | These watchers are normal Perl objects with normal Perl lifetime. After |
106 | creating a watcher it will immediately "watch" for events and invoke |
122 | creating a watcher it will immediately "watch" for events and invoke the |
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123 | callback when the event occurs (of course, only when the event model |
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124 | is in control). |
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125 | |
107 | the callback. To disable the watcher you have to destroy it (e.g. by |
126 | To disable the watcher you have to destroy it (e.g. by setting the |
108 | setting the variable that stores it to C<undef> or otherwise deleting all |
127 | variable you store it in to C<undef> or otherwise deleting all references |
109 | references to it). |
128 | to it). |
110 | |
129 | |
111 | All watchers are created by calling a method on the C<AnyEvent> class. |
130 | All watchers are created by calling a method on the C<AnyEvent> class. |
112 | |
131 | |
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132 | Many watchers either are used with "recursion" (repeating timers for |
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133 | example), or need to refer to their watcher object in other ways. |
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134 | |
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135 | An any way to achieve that is this pattern: |
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136 | |
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137 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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138 | # you can use $w here, for example to undef it |
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139 | undef $w; |
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140 | }); |
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141 | |
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142 | Note that C<my $w; $w => combination. This is necessary because in Perl, |
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143 | my variables are only visible after the statement in which they are |
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144 | declared. |
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145 | |
113 | =head2 IO WATCHERS |
146 | =head2 I/O WATCHERS |
114 | |
147 | |
115 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
148 | You can create an I/O watcher by calling the C<< AnyEvent->io >> method |
116 | the following mandatory arguments: |
149 | with the following mandatory key-value pairs as arguments: |
117 | |
150 | |
118 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
151 | C<fh> the Perl I<file handle> (I<not> file descriptor) to watch |
119 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
152 | for events. C<poll> must be a string that is either C<r> or C<w>, |
120 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback |
153 | which creates a watcher waiting for "r"eadable or "w"ritable events, |
121 | to invoke everytime the filehandle becomes ready. |
154 | respectively. C<cb> is the callback to invoke each time the file handle |
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155 | becomes ready. |
122 | |
156 | |
123 | Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on |
157 | Although the callback might get passed parameters, their value and |
124 | a socket you can have one r + one w, not any more (limitation comes from |
158 | presence is undefined and you cannot rely on them. Portable AnyEvent |
125 | Tk - if you are sure you are not using Tk this limitation is gone). |
159 | callbacks cannot use arguments passed to I/O watcher callbacks. |
126 | |
160 | |
127 | Filehandles will be kept alive, so as long as the watcher exists, the |
161 | The I/O watcher might use the underlying file descriptor or a copy of it. |
128 | filehandle exists, too. |
162 | You must not close a file handle as long as any watcher is active on the |
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163 | underlying file descriptor. |
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164 | |
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165 | Some event loops issue spurious readyness notifications, so you should |
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166 | always use non-blocking calls when reading/writing from/to your file |
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167 | handles. |
129 | |
168 | |
130 | Example: |
169 | Example: |
131 | |
170 | |
132 | # wait for readability of STDIN, then read a line and disable the watcher |
171 | # wait for readability of STDIN, then read a line and disable the watcher |
133 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
172 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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139 | =head2 TIME WATCHERS |
178 | =head2 TIME WATCHERS |
140 | |
179 | |
141 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
180 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
142 | method with the following mandatory arguments: |
181 | method with the following mandatory arguments: |
143 | |
182 | |
144 | C<after> after how many seconds (fractions are supported) should the timer |
183 | C<after> specifies after how many seconds (fractional values are |
145 | activate. C<cb> the callback to invoke. |
184 | supported) the callback should be invoked. C<cb> is the callback to invoke |
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185 | in that case. |
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186 | |
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187 | Although the callback might get passed parameters, their value and |
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188 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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189 | callbacks cannot use arguments passed to time watcher callbacks. |
146 | |
190 | |
147 | The timer callback will be invoked at most once: if you want a repeating |
191 | The timer callback will be invoked at most once: if you want a repeating |
148 | timer you have to create a new watcher (this is a limitation by both Tk |
192 | timer you have to create a new watcher (this is a limitation by both Tk |
149 | and Glib). |
193 | and Glib). |
150 | |
194 | |
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156 | }); |
200 | }); |
157 | |
201 | |
158 | # to cancel the timer: |
202 | # to cancel the timer: |
159 | undef $w; |
203 | undef $w; |
160 | |
204 | |
161 | =head2 CONDITION WATCHERS |
205 | Example 2: |
162 | |
206 | |
163 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
207 | # fire an event after 0.5 seconds, then roughly every second |
164 | method without any arguments. |
208 | my $w; |
165 | |
209 | |
166 | A condition watcher watches for a condition - precisely that the C<< |
210 | my $cb = sub { |
167 | ->broadcast >> method has been called. |
211 | # cancel the old timer while creating a new one |
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212 | $w = AnyEvent->timer (after => 1, cb => $cb); |
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213 | }; |
168 | |
214 | |
169 | Note that condition watchers recurse into the event loop - if you have |
215 | # start the "loop" by creating the first watcher |
170 | two watchers that call C<< ->wait >> in a round-robbin fashion, you |
216 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
171 | lose. Therefore, condition watchers are good to export to your caller, but |
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172 | you should avoid making a blocking wait, at least in callbacks, as this |
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173 | usually asks for trouble. |
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174 | |
217 | |
175 | The watcher has only two methods: |
218 | =head3 TIMING ISSUES |
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219 | |
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220 | There are two ways to handle timers: based on real time (relative, "fire |
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221 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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222 | o'clock"). |
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223 | |
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224 | While most event loops expect timers to specified in a relative way, they |
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225 | use absolute time internally. This makes a difference when your clock |
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226 | "jumps", for example, when ntp decides to set your clock backwards from |
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227 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
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228 | fire "after" a second might actually take six years to finally fire. |
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229 | |
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230 | AnyEvent cannot compensate for this. The only event loop that is conscious |
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231 | about these issues is L<EV>, which offers both relative (ev_timer, based |
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232 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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233 | timers. |
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234 | |
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235 | AnyEvent always prefers relative timers, if available, matching the |
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236 | AnyEvent API. |
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237 | |
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238 | AnyEvent has two additional methods that return the "current time": |
176 | |
239 | |
177 | =over 4 |
240 | =over 4 |
178 | |
241 | |
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242 | =item AnyEvent->time |
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243 | |
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244 | This returns the "current wallclock time" as a fractional number of |
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245 | seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time> |
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246 | return, and the result is guaranteed to be compatible with those). |
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247 | |
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248 | It progresses independently of any event loop processing, i.e. each call |
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249 | will check the system clock, which usually gets updated frequently. |
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250 | |
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251 | =item AnyEvent->now |
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252 | |
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253 | This also returns the "current wallclock time", but unlike C<time>, above, |
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254 | this value might change only once per event loop iteration, depending on |
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255 | the event loop (most return the same time as C<time>, above). This is the |
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256 | time that AnyEvent's timers get scheduled against. |
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257 | |
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258 | I<In almost all cases (in all cases if you don't care), this is the |
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259 | function to call when you want to know the current time.> |
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260 | |
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261 | This function is also often faster then C<< AnyEvent->time >>, and |
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262 | thus the preferred method if you want some timestamp (for example, |
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263 | L<AnyEvent::Handle> uses this to update it's activity timeouts). |
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264 | |
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265 | The rest of this section is only of relevance if you try to be very exact |
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266 | with your timing, you can skip it without bad conscience. |
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267 | |
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268 | For a practical example of when these times differ, consider L<Event::Lib> |
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269 | and L<EV> and the following set-up: |
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270 | |
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271 | The event loop is running and has just invoked one of your callback at |
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272 | time=500 (assume no other callbacks delay processing). In your callback, |
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273 | you wait a second by executing C<sleep 1> (blocking the process for a |
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274 | second) and then (at time=501) you create a relative timer that fires |
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275 | after three seconds. |
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276 | |
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277 | With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will |
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278 | both return C<501>, because that is the current time, and the timer will |
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279 | be scheduled to fire at time=504 (C<501> + C<3>). |
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280 | |
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281 | With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current |
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282 | time), but C<< AnyEvent->now >> returns C<500>, as that is the time the |
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283 | last event processing phase started. With L<EV>, your timer gets scheduled |
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284 | to run at time=503 (C<500> + C<3>). |
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285 | |
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286 | In one sense, L<Event::Lib> is more exact, as it uses the current time |
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287 | regardless of any delays introduced by event processing. However, most |
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288 | callbacks do not expect large delays in processing, so this causes a |
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289 | higher drift (and a lot more system calls to get the current time). |
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290 | |
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291 | In another sense, L<EV> is more exact, as your timer will be scheduled at |
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292 | the same time, regardless of how long event processing actually took. |
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293 | |
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294 | In either case, if you care (and in most cases, you don't), then you |
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295 | can get whatever behaviour you want with any event loop, by taking the |
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296 | difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into |
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297 | account. |
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298 | |
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299 | =back |
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300 | |
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301 | =head2 SIGNAL WATCHERS |
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302 | |
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303 | You can watch for signals using a signal watcher, C<signal> is the signal |
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304 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
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305 | be invoked whenever a signal occurs. |
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306 | |
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307 | Although the callback might get passed parameters, their value and |
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308 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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309 | callbacks cannot use arguments passed to signal watcher callbacks. |
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310 | |
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311 | Multiple signal occurrences can be clumped together into one callback |
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312 | invocation, and callback invocation will be synchronous. Synchronous means |
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313 | that it might take a while until the signal gets handled by the process, |
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314 | but it is guaranteed not to interrupt any other callbacks. |
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315 | |
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316 | The main advantage of using these watchers is that you can share a signal |
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317 | between multiple watchers. |
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318 | |
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319 | This watcher might use C<%SIG>, so programs overwriting those signals |
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320 | directly will likely not work correctly. |
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321 | |
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322 | Example: exit on SIGINT |
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323 | |
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324 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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325 | |
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326 | =head2 CHILD PROCESS WATCHERS |
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327 | |
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328 | You can also watch on a child process exit and catch its exit status. |
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329 | |
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330 | The child process is specified by the C<pid> argument (if set to C<0>, it |
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331 | watches for any child process exit). The watcher will trigger as often |
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332 | as status change for the child are received. This works by installing a |
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333 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
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334 | and exit status (as returned by waitpid), so unlike other watcher types, |
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335 | you I<can> rely on child watcher callback arguments. |
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336 | |
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337 | There is a slight catch to child watchers, however: you usually start them |
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338 | I<after> the child process was created, and this means the process could |
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339 | have exited already (and no SIGCHLD will be sent anymore). |
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340 | |
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341 | Not all event models handle this correctly (POE doesn't), but even for |
|
|
342 | event models that I<do> handle this correctly, they usually need to be |
|
|
343 | loaded before the process exits (i.e. before you fork in the first place). |
|
|
344 | |
|
|
345 | This means you cannot create a child watcher as the very first thing in an |
|
|
346 | AnyEvent program, you I<have> to create at least one watcher before you |
|
|
347 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
|
|
348 | |
|
|
349 | Example: fork a process and wait for it |
|
|
350 | |
|
|
351 | my $done = AnyEvent->condvar; |
|
|
352 | |
|
|
353 | my $pid = fork or exit 5; |
|
|
354 | |
|
|
355 | my $w = AnyEvent->child ( |
|
|
356 | pid => $pid, |
|
|
357 | cb => sub { |
|
|
358 | my ($pid, $status) = @_; |
|
|
359 | warn "pid $pid exited with status $status"; |
|
|
360 | $done->send; |
|
|
361 | }, |
|
|
362 | ); |
|
|
363 | |
|
|
364 | # do something else, then wait for process exit |
|
|
365 | $done->recv; |
|
|
366 | |
|
|
367 | =head2 CONDITION VARIABLES |
|
|
368 | |
|
|
369 | If you are familiar with some event loops you will know that all of them |
|
|
370 | require you to run some blocking "loop", "run" or similar function that |
|
|
371 | will actively watch for new events and call your callbacks. |
|
|
372 | |
|
|
373 | AnyEvent is different, it expects somebody else to run the event loop and |
|
|
374 | will only block when necessary (usually when told by the user). |
|
|
375 | |
|
|
376 | The instrument to do that is called a "condition variable", so called |
|
|
377 | because they represent a condition that must become true. |
|
|
378 | |
|
|
379 | Condition variables can be created by calling the C<< AnyEvent->condvar |
|
|
380 | >> method, usually without arguments. The only argument pair allowed is |
|
|
381 | C<cb>, which specifies a callback to be called when the condition variable |
|
|
382 | becomes true. |
|
|
383 | |
|
|
384 | After creation, the condition variable is "false" until it becomes "true" |
|
|
385 | by calling the C<send> method (or calling the condition variable as if it |
|
|
386 | were a callback, read about the caveats in the description for the C<< |
|
|
387 | ->send >> method). |
|
|
388 | |
|
|
389 | Condition variables are similar to callbacks, except that you can |
|
|
390 | optionally wait for them. They can also be called merge points - points |
|
|
391 | in time where multiple outstanding events have been processed. And yet |
|
|
392 | another way to call them is transactions - each condition variable can be |
|
|
393 | used to represent a transaction, which finishes at some point and delivers |
|
|
394 | a result. |
|
|
395 | |
|
|
396 | Condition variables are very useful to signal that something has finished, |
|
|
397 | for example, if you write a module that does asynchronous http requests, |
|
|
398 | then a condition variable would be the ideal candidate to signal the |
|
|
399 | availability of results. The user can either act when the callback is |
|
|
400 | called or can synchronously C<< ->recv >> for the results. |
|
|
401 | |
|
|
402 | You can also use them to simulate traditional event loops - for example, |
|
|
403 | you can block your main program until an event occurs - for example, you |
|
|
404 | could C<< ->recv >> in your main program until the user clicks the Quit |
|
|
405 | button of your app, which would C<< ->send >> the "quit" event. |
|
|
406 | |
|
|
407 | Note that condition variables recurse into the event loop - if you have |
|
|
408 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
|
|
409 | lose. Therefore, condition variables are good to export to your caller, but |
|
|
410 | you should avoid making a blocking wait yourself, at least in callbacks, |
|
|
411 | as this asks for trouble. |
|
|
412 | |
|
|
413 | Condition variables are represented by hash refs in perl, and the keys |
|
|
414 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
|
|
415 | easy (it is often useful to build your own transaction class on top of |
|
|
416 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
|
|
417 | it's C<new> method in your own C<new> method. |
|
|
418 | |
|
|
419 | There are two "sides" to a condition variable - the "producer side" which |
|
|
420 | eventually calls C<< -> send >>, and the "consumer side", which waits |
|
|
421 | for the send to occur. |
|
|
422 | |
|
|
423 | Example: wait for a timer. |
|
|
424 | |
|
|
425 | # wait till the result is ready |
|
|
426 | my $result_ready = AnyEvent->condvar; |
|
|
427 | |
|
|
428 | # do something such as adding a timer |
|
|
429 | # or socket watcher the calls $result_ready->send |
|
|
430 | # when the "result" is ready. |
|
|
431 | # in this case, we simply use a timer: |
|
|
432 | my $w = AnyEvent->timer ( |
|
|
433 | after => 1, |
|
|
434 | cb => sub { $result_ready->send }, |
|
|
435 | ); |
|
|
436 | |
|
|
437 | # this "blocks" (while handling events) till the callback |
|
|
438 | # calls send |
|
|
439 | $result_ready->recv; |
|
|
440 | |
|
|
441 | Example: wait for a timer, but take advantage of the fact that |
|
|
442 | condition variables are also code references. |
|
|
443 | |
|
|
444 | my $done = AnyEvent->condvar; |
|
|
445 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
|
|
446 | $done->recv; |
|
|
447 | |
|
|
448 | =head3 METHODS FOR PRODUCERS |
|
|
449 | |
|
|
450 | These methods should only be used by the producing side, i.e. the |
|
|
451 | code/module that eventually sends the signal. Note that it is also |
|
|
452 | the producer side which creates the condvar in most cases, but it isn't |
|
|
453 | uncommon for the consumer to create it as well. |
|
|
454 | |
|
|
455 | =over 4 |
|
|
456 | |
|
|
457 | =item $cv->send (...) |
|
|
458 | |
|
|
459 | Flag the condition as ready - a running C<< ->recv >> and all further |
|
|
460 | calls to C<recv> will (eventually) return after this method has been |
|
|
461 | called. If nobody is waiting the send will be remembered. |
|
|
462 | |
|
|
463 | If a callback has been set on the condition variable, it is called |
|
|
464 | immediately from within send. |
|
|
465 | |
|
|
466 | Any arguments passed to the C<send> call will be returned by all |
|
|
467 | future C<< ->recv >> calls. |
|
|
468 | |
|
|
469 | Condition variables are overloaded so one can call them directly |
|
|
470 | (as a code reference). Calling them directly is the same as calling |
|
|
471 | C<send>. Note, however, that many C-based event loops do not handle |
|
|
472 | overloading, so as tempting as it may be, passing a condition variable |
|
|
473 | instead of a callback does not work. Both the pure perl and EV loops |
|
|
474 | support overloading, however, as well as all functions that use perl to |
|
|
475 | invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for |
|
|
476 | example). |
|
|
477 | |
|
|
478 | =item $cv->croak ($error) |
|
|
479 | |
|
|
480 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
|
|
481 | C<Carp::croak> with the given error message/object/scalar. |
|
|
482 | |
|
|
483 | This can be used to signal any errors to the condition variable |
|
|
484 | user/consumer. |
|
|
485 | |
|
|
486 | =item $cv->begin ([group callback]) |
|
|
487 | |
179 | =item $cv->wait |
488 | =item $cv->end |
180 | |
489 | |
181 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
490 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
|
|
491 | |
|
|
492 | These two methods can be used to combine many transactions/events into |
|
|
493 | one. For example, a function that pings many hosts in parallel might want |
|
|
494 | to use a condition variable for the whole process. |
|
|
495 | |
|
|
496 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
497 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
498 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
499 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
500 | callback was set, C<send> will be called without any arguments. |
|
|
501 | |
|
|
502 | Let's clarify this with the ping example: |
|
|
503 | |
|
|
504 | my $cv = AnyEvent->condvar; |
|
|
505 | |
|
|
506 | my %result; |
|
|
507 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
508 | |
|
|
509 | for my $host (@list_of_hosts) { |
|
|
510 | $cv->begin; |
|
|
511 | ping_host_then_call_callback $host, sub { |
|
|
512 | $result{$host} = ...; |
|
|
513 | $cv->end; |
|
|
514 | }; |
|
|
515 | } |
|
|
516 | |
|
|
517 | $cv->end; |
|
|
518 | |
|
|
519 | This code fragment supposedly pings a number of hosts and calls |
|
|
520 | C<send> after results for all then have have been gathered - in any |
|
|
521 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
522 | each ping request and calls C<end> when it has received some result for |
|
|
523 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
524 | results arrive is not relevant. |
|
|
525 | |
|
|
526 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
527 | loop, which serves two important purposes: first, it sets the callback |
|
|
528 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
529 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
530 | doesn't execute once). |
|
|
531 | |
|
|
532 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
533 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
534 | is called at least once, and then, for each subrequest you start, call |
|
|
535 | C<begin> and for each subrequest you finish, call C<end>. |
|
|
536 | |
|
|
537 | =back |
|
|
538 | |
|
|
539 | =head3 METHODS FOR CONSUMERS |
|
|
540 | |
|
|
541 | These methods should only be used by the consuming side, i.e. the |
|
|
542 | code awaits the condition. |
|
|
543 | |
|
|
544 | =over 4 |
|
|
545 | |
|
|
546 | =item $cv->recv |
|
|
547 | |
|
|
548 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
182 | called on c<$cv>, while servicing other watchers normally. |
549 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
550 | normally. |
183 | |
551 | |
184 | You can only wait once on a condition - additional calls will return |
552 | You can only wait once on a condition - additional calls are valid but |
185 | immediately. |
553 | will return immediately. |
|
|
554 | |
|
|
555 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
556 | function will call C<croak>. |
|
|
557 | |
|
|
558 | In list context, all parameters passed to C<send> will be returned, |
|
|
559 | in scalar context only the first one will be returned. |
186 | |
560 | |
187 | Not all event models support a blocking wait - some die in that case |
561 | Not all event models support a blocking wait - some die in that case |
188 | (programs might want to do that so they stay interactive), so I<if you |
562 | (programs might want to do that to stay interactive), so I<if you are |
189 | are using this from a module, never require a blocking wait>, but let the |
563 | using this from a module, never require a blocking wait>, but let the |
190 | caller decide wether the call will block or not (for example, by coupling |
564 | caller decide whether the call will block or not (for example, by coupling |
191 | condition variables with some kind of request results and supporting |
565 | condition variables with some kind of request results and supporting |
192 | callbacks so the caller knows that getting the result will not block, |
566 | callbacks so the caller knows that getting the result will not block, |
193 | while still suppporting blocking waits if the caller so desires). |
567 | while still supporting blocking waits if the caller so desires). |
194 | |
568 | |
195 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
569 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
196 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
570 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
197 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
571 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
198 | can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event> |
572 | can supply. |
199 | explicitly support concurrent C<< ->wait >>'s from different coroutines, |
|
|
200 | however). |
|
|
201 | |
573 | |
202 | =item $cv->broadcast |
574 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
|
|
575 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
|
|
576 | versions and also integrates coroutines into AnyEvent, making blocking |
|
|
577 | C<< ->recv >> calls perfectly safe as long as they are done from another |
|
|
578 | coroutine (one that doesn't run the event loop). |
203 | |
579 | |
204 | Flag the condition as ready - a running C<< ->wait >> and all further |
580 | You can ensure that C<< -recv >> never blocks by setting a callback and |
205 | calls to C<wait> will return after this method has been called. If nobody |
581 | only calling C<< ->recv >> from within that callback (or at a later |
206 | is waiting the broadcast will be remembered.. |
582 | time). This will work even when the event loop does not support blocking |
|
|
583 | waits otherwise. |
207 | |
584 | |
208 | Example: |
585 | =item $bool = $cv->ready |
209 | |
586 | |
210 | # wait till the result is ready |
587 | Returns true when the condition is "true", i.e. whether C<send> or |
211 | my $result_ready = AnyEvent->condvar; |
588 | C<croak> have been called. |
212 | |
589 | |
213 | # do something such as adding a timer |
590 | =item $cb = $cv->cb ([new callback]) |
214 | # or socket watcher the calls $result_ready->broadcast |
|
|
215 | # when the "result" is ready. |
|
|
216 | |
591 | |
217 | $result_ready->wait; |
592 | This is a mutator function that returns the callback set and optionally |
|
|
593 | replaces it before doing so. |
|
|
594 | |
|
|
595 | The callback will be called when the condition becomes "true", i.e. when |
|
|
596 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
|
|
597 | or at any later time is guaranteed not to block. |
218 | |
598 | |
219 | =back |
599 | =back |
220 | |
600 | |
221 | =head2 SIGNAL WATCHERS |
601 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
222 | |
|
|
223 | You can listen for signals using a signal watcher, C<signal> is the signal |
|
|
224 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
|
|
225 | together into one callback invocation, and callback invocation might or |
|
|
226 | might not be asynchronous. |
|
|
227 | |
|
|
228 | These watchers might use C<%SIG>, so programs overwriting those signals |
|
|
229 | directly will likely not work correctly. |
|
|
230 | |
|
|
231 | Example: exit on SIGINT |
|
|
232 | |
|
|
233 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
|
|
234 | |
|
|
235 | =head2 CHILD PROCESS WATCHERS |
|
|
236 | |
|
|
237 | You can also listen for the status of a child process specified by the |
|
|
238 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
|
|
239 | trigger as often as status change for the child are received. This works |
|
|
240 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
|
|
241 | the pid and exit status (as returned by waitpid). |
|
|
242 | |
|
|
243 | Example: wait for pid 1333 |
|
|
244 | |
|
|
245 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
|
|
246 | |
|
|
247 | =head1 GLOBALS |
|
|
248 | |
602 | |
249 | =over 4 |
603 | =over 4 |
250 | |
604 | |
251 | =item $AnyEvent::MODEL |
605 | =item $AnyEvent::MODEL |
252 | |
606 | |
… | |
… | |
256 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
610 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
257 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
611 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
258 | |
612 | |
259 | The known classes so far are: |
613 | The known classes so far are: |
260 | |
614 | |
261 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
|
|
262 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
615 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
263 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
|
|
264 | AnyEvent::Impl::Event based on Event, also second best choice :) |
616 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
617 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
265 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
618 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
266 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
619 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
267 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
620 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
621 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
622 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
623 | |
|
|
624 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
625 | watching file handles. However, you can use WxWidgets through the |
|
|
626 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
627 | second, which was considered to be too horrible to even consider for |
|
|
628 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
|
|
629 | it's adaptor. |
|
|
630 | |
|
|
631 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
|
|
632 | autodetecting them. |
268 | |
633 | |
269 | =item AnyEvent::detect |
634 | =item AnyEvent::detect |
270 | |
635 | |
271 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
636 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
272 | necessary. You should only call this function right before you would have |
637 | if necessary. You should only call this function right before you would |
273 | created an AnyEvent watcher anyway, that is, very late at runtime. |
638 | have created an AnyEvent watcher anyway, that is, as late as possible at |
|
|
639 | runtime. |
|
|
640 | |
|
|
641 | =item $guard = AnyEvent::post_detect { BLOCK } |
|
|
642 | |
|
|
643 | Arranges for the code block to be executed as soon as the event model is |
|
|
644 | autodetected (or immediately if this has already happened). |
|
|
645 | |
|
|
646 | If called in scalar or list context, then it creates and returns an object |
|
|
647 | that automatically removes the callback again when it is destroyed. See |
|
|
648 | L<Coro::BDB> for a case where this is useful. |
|
|
649 | |
|
|
650 | =item @AnyEvent::post_detect |
|
|
651 | |
|
|
652 | If there are any code references in this array (you can C<push> to it |
|
|
653 | before or after loading AnyEvent), then they will called directly after |
|
|
654 | the event loop has been chosen. |
|
|
655 | |
|
|
656 | You should check C<$AnyEvent::MODEL> before adding to this array, though: |
|
|
657 | if it contains a true value then the event loop has already been detected, |
|
|
658 | and the array will be ignored. |
|
|
659 | |
|
|
660 | Best use C<AnyEvent::post_detect { BLOCK }> instead. |
274 | |
661 | |
275 | =back |
662 | =back |
276 | |
663 | |
277 | =head1 WHAT TO DO IN A MODULE |
664 | =head1 WHAT TO DO IN A MODULE |
278 | |
665 | |
279 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
666 | As a module author, you should C<use AnyEvent> and call AnyEvent methods |
280 | freely, but you should not load a specific event module or rely on it. |
667 | freely, but you should not load a specific event module or rely on it. |
281 | |
668 | |
282 | Be careful when you create watchers in the module body - Anyevent will |
669 | Be careful when you create watchers in the module body - AnyEvent will |
283 | decide which event module to use as soon as the first method is called, so |
670 | decide which event module to use as soon as the first method is called, so |
284 | by calling AnyEvent in your module body you force the user of your module |
671 | by calling AnyEvent in your module body you force the user of your module |
285 | to load the event module first. |
672 | to load the event module first. |
286 | |
673 | |
|
|
674 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
|
|
675 | the C<< ->send >> method has been called on it already. This is |
|
|
676 | because it will stall the whole program, and the whole point of using |
|
|
677 | events is to stay interactive. |
|
|
678 | |
|
|
679 | It is fine, however, to call C<< ->recv >> when the user of your module |
|
|
680 | requests it (i.e. if you create a http request object ad have a method |
|
|
681 | called C<results> that returns the results, it should call C<< ->recv >> |
|
|
682 | freely, as the user of your module knows what she is doing. always). |
|
|
683 | |
287 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
684 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
288 | |
685 | |
289 | There will always be a single main program - the only place that should |
686 | There will always be a single main program - the only place that should |
290 | dictate which event model to use. |
687 | dictate which event model to use. |
291 | |
688 | |
292 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
689 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
293 | do anything special and let AnyEvent decide which implementation to chose. |
690 | do anything special (it does not need to be event-based) and let AnyEvent |
|
|
691 | decide which implementation to chose if some module relies on it. |
294 | |
692 | |
295 | If the main program relies on a specific event model (for example, in Gtk2 |
693 | If the main program relies on a specific event model - for example, in |
296 | programs you have to rely on either Glib or Glib::Event), you should load |
694 | Gtk2 programs you have to rely on the Glib module - you should load the |
297 | it before loading AnyEvent or any module that uses it, generally, as early |
695 | event module before loading AnyEvent or any module that uses it: generally |
298 | as possible. The reason is that modules might create watchers when they |
696 | speaking, you should load it as early as possible. The reason is that |
299 | are loaded, and AnyEvent will decide on the event model to use as soon as |
697 | modules might create watchers when they are loaded, and AnyEvent will |
300 | it creates watchers, and it might chose the wrong one unless you load the |
698 | decide on the event model to use as soon as it creates watchers, and it |
301 | correct one yourself. |
699 | might chose the wrong one unless you load the correct one yourself. |
302 | |
700 | |
303 | You can chose to use a rather inefficient pure-perl implementation by |
701 | You can chose to use a pure-perl implementation by loading the |
304 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
702 | C<AnyEvent::Impl::Perl> module, which gives you similar behaviour |
305 | generally better. |
703 | everywhere, but letting AnyEvent chose the model is generally better. |
|
|
704 | |
|
|
705 | =head2 MAINLOOP EMULATION |
|
|
706 | |
|
|
707 | Sometimes (often for short test scripts, or even standalone programs who |
|
|
708 | only want to use AnyEvent), you do not want to run a specific event loop. |
|
|
709 | |
|
|
710 | In that case, you can use a condition variable like this: |
|
|
711 | |
|
|
712 | AnyEvent->condvar->recv; |
|
|
713 | |
|
|
714 | This has the effect of entering the event loop and looping forever. |
|
|
715 | |
|
|
716 | Note that usually your program has some exit condition, in which case |
|
|
717 | it is better to use the "traditional" approach of storing a condition |
|
|
718 | variable somewhere, waiting for it, and sending it when the program should |
|
|
719 | exit cleanly. |
|
|
720 | |
|
|
721 | |
|
|
722 | =head1 OTHER MODULES |
|
|
723 | |
|
|
724 | The following is a non-exhaustive list of additional modules that use |
|
|
725 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
726 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
727 | available via CPAN. |
|
|
728 | |
|
|
729 | =over 4 |
|
|
730 | |
|
|
731 | =item L<AnyEvent::Util> |
|
|
732 | |
|
|
733 | Contains various utility functions that replace often-used but blocking |
|
|
734 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
735 | |
|
|
736 | =item L<AnyEvent::Handle> |
|
|
737 | |
|
|
738 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
739 | |
|
|
740 | =item L<AnyEvent::Socket> |
|
|
741 | |
|
|
742 | Provides various utility functions for (internet protocol) sockets, |
|
|
743 | addresses and name resolution. Also functions to create non-blocking tcp |
|
|
744 | connections or tcp servers, with IPv6 and SRV record support and more. |
|
|
745 | |
|
|
746 | =item L<AnyEvent::DNS> |
|
|
747 | |
|
|
748 | Provides rich asynchronous DNS resolver capabilities. |
|
|
749 | |
|
|
750 | =item L<AnyEvent::HTTPD> |
|
|
751 | |
|
|
752 | Provides a simple web application server framework. |
|
|
753 | |
|
|
754 | =item L<AnyEvent::FastPing> |
|
|
755 | |
|
|
756 | The fastest ping in the west. |
|
|
757 | |
|
|
758 | =item L<Net::IRC3> |
|
|
759 | |
|
|
760 | AnyEvent based IRC client module family. |
|
|
761 | |
|
|
762 | =item L<Net::XMPP2> |
|
|
763 | |
|
|
764 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
765 | |
|
|
766 | =item L<Net::FCP> |
|
|
767 | |
|
|
768 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
769 | of AnyEvent. |
|
|
770 | |
|
|
771 | =item L<Event::ExecFlow> |
|
|
772 | |
|
|
773 | High level API for event-based execution flow control. |
|
|
774 | |
|
|
775 | =item L<Coro> |
|
|
776 | |
|
|
777 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
|
|
778 | |
|
|
779 | =item L<AnyEvent::AIO>, L<IO::AIO> |
|
|
780 | |
|
|
781 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
782 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
783 | together. |
|
|
784 | |
|
|
785 | =item L<AnyEvent::BDB>, L<BDB> |
|
|
786 | |
|
|
787 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses |
|
|
788 | IO::AIO and AnyEvent together. |
|
|
789 | |
|
|
790 | =item L<IO::Lambda> |
|
|
791 | |
|
|
792 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
793 | |
|
|
794 | =back |
306 | |
795 | |
307 | =cut |
796 | =cut |
308 | |
797 | |
309 | package AnyEvent; |
798 | package AnyEvent; |
310 | |
799 | |
311 | no warnings; |
800 | no warnings; |
312 | use strict; |
801 | use strict; |
313 | |
802 | |
314 | use Carp; |
803 | use Carp; |
315 | |
804 | |
316 | our $VERSION = '3.0'; |
805 | our $VERSION = '4.05'; |
317 | our $MODEL; |
806 | our $MODEL; |
318 | |
807 | |
319 | our $AUTOLOAD; |
808 | our $AUTOLOAD; |
320 | our @ISA; |
809 | our @ISA; |
321 | |
810 | |
|
|
811 | our @REGISTRY; |
|
|
812 | |
|
|
813 | our $WIN32; |
|
|
814 | |
|
|
815 | BEGIN { |
|
|
816 | my $win32 = ! ! ($^O =~ /mswin32/i); |
|
|
817 | eval "sub WIN32(){ $win32 }"; |
|
|
818 | } |
|
|
819 | |
322 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
820 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
323 | |
821 | |
324 | our @REGISTRY; |
822 | our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred |
|
|
823 | |
|
|
824 | { |
|
|
825 | my $idx; |
|
|
826 | $PROTOCOL{$_} = ++$idx |
|
|
827 | for reverse split /\s*,\s*/, |
|
|
828 | $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; |
|
|
829 | } |
325 | |
830 | |
326 | my @models = ( |
831 | my @models = ( |
327 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
|
|
328 | [EV:: => AnyEvent::Impl::EV::], |
832 | [EV:: => AnyEvent::Impl::EV::], |
329 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
|
|
330 | [Event:: => AnyEvent::Impl::Event::], |
833 | [Event:: => AnyEvent::Impl::Event::], |
331 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
332 | [Tk:: => AnyEvent::Impl::Tk::], |
|
|
333 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
834 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
|
|
835 | # everything below here will not be autoprobed |
|
|
836 | # as the pureperl backend should work everywhere |
|
|
837 | # and is usually faster |
|
|
838 | [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles |
|
|
839 | [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers |
|
|
840 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
|
|
841 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
|
|
842 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
|
|
843 | [Wx:: => AnyEvent::Impl::POE::], |
|
|
844 | [Prima:: => AnyEvent::Impl::POE::], |
334 | ); |
845 | ); |
335 | |
846 | |
336 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
847 | our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); |
|
|
848 | |
|
|
849 | our @post_detect; |
|
|
850 | |
|
|
851 | sub post_detect(&) { |
|
|
852 | my ($cb) = @_; |
|
|
853 | |
|
|
854 | if ($MODEL) { |
|
|
855 | $cb->(); |
|
|
856 | |
|
|
857 | 1 |
|
|
858 | } else { |
|
|
859 | push @post_detect, $cb; |
|
|
860 | |
|
|
861 | defined wantarray |
|
|
862 | ? bless \$cb, "AnyEvent::Util::PostDetect" |
|
|
863 | : () |
|
|
864 | } |
|
|
865 | } |
|
|
866 | |
|
|
867 | sub AnyEvent::Util::PostDetect::DESTROY { |
|
|
868 | @post_detect = grep $_ != ${$_[0]}, @post_detect; |
|
|
869 | } |
337 | |
870 | |
338 | sub detect() { |
871 | sub detect() { |
339 | unless ($MODEL) { |
872 | unless ($MODEL) { |
340 | no strict 'refs'; |
873 | no strict 'refs'; |
|
|
874 | local $SIG{__DIE__}; |
|
|
875 | |
|
|
876 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
|
|
877 | my $model = "AnyEvent::Impl::$1"; |
|
|
878 | if (eval "require $model") { |
|
|
879 | $MODEL = $model; |
|
|
880 | warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; |
|
|
881 | } else { |
|
|
882 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
|
|
883 | } |
|
|
884 | } |
341 | |
885 | |
342 | # check for already loaded models |
886 | # check for already loaded models |
|
|
887 | unless ($MODEL) { |
343 | for (@REGISTRY, @models) { |
888 | for (@REGISTRY, @models) { |
344 | my ($package, $model) = @$_; |
889 | my ($package, $model) = @$_; |
345 | if (${"$package\::VERSION"} > 0) { |
890 | if (${"$package\::VERSION"} > 0) { |
346 | if (eval "require $model") { |
891 | if (eval "require $model") { |
347 | $MODEL = $model; |
892 | $MODEL = $model; |
348 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
893 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
349 | last; |
894 | last; |
|
|
895 | } |
350 | } |
896 | } |
351 | } |
897 | } |
352 | } |
|
|
353 | |
898 | |
354 | unless ($MODEL) { |
899 | unless ($MODEL) { |
355 | # try to load a model |
900 | # try to load a model |
356 | |
901 | |
357 | for (@REGISTRY, @models) { |
902 | for (@REGISTRY, @models) { |
358 | my ($package, $model) = @$_; |
903 | my ($package, $model) = @$_; |
359 | if (eval "require $package" |
904 | if (eval "require $package" |
360 | and ${"$package\::VERSION"} > 0 |
905 | and ${"$package\::VERSION"} > 0 |
361 | and eval "require $model") { |
906 | and eval "require $model") { |
362 | $MODEL = $model; |
907 | $MODEL = $model; |
363 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
908 | warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; |
364 | last; |
909 | last; |
|
|
910 | } |
365 | } |
911 | } |
|
|
912 | |
|
|
913 | $MODEL |
|
|
914 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; |
366 | } |
915 | } |
367 | |
|
|
368 | $MODEL |
|
|
369 | or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event), Glib or Tk."; |
|
|
370 | } |
916 | } |
371 | |
917 | |
372 | unshift @ISA, $MODEL; |
918 | unshift @ISA, $MODEL; |
373 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
919 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
|
|
920 | |
|
|
921 | (shift @post_detect)->() while @post_detect; |
374 | } |
922 | } |
375 | |
923 | |
376 | $MODEL |
924 | $MODEL |
377 | } |
925 | } |
378 | |
926 | |
… | |
… | |
388 | $class->$func (@_); |
936 | $class->$func (@_); |
389 | } |
937 | } |
390 | |
938 | |
391 | package AnyEvent::Base; |
939 | package AnyEvent::Base; |
392 | |
940 | |
|
|
941 | # default implementation for now and time |
|
|
942 | |
|
|
943 | use Time::HiRes (); |
|
|
944 | |
|
|
945 | sub time { Time::HiRes::time } |
|
|
946 | sub now { Time::HiRes::time } |
|
|
947 | |
393 | # default implementation for ->condvar, ->wait, ->broadcast |
948 | # default implementation for ->condvar |
394 | |
949 | |
395 | sub condvar { |
950 | sub condvar { |
396 | bless \my $flag, "AnyEvent::Base::CondVar" |
951 | bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: |
397 | } |
|
|
398 | |
|
|
399 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
400 | ${$_[0]}++; |
|
|
401 | } |
|
|
402 | |
|
|
403 | sub AnyEvent::Base::CondVar::wait { |
|
|
404 | AnyEvent->one_event while !${$_[0]}; |
|
|
405 | } |
952 | } |
406 | |
953 | |
407 | # default implementation for ->signal |
954 | # default implementation for ->signal |
408 | |
955 | |
409 | our %SIG_CB; |
956 | our %SIG_CB; |
… | |
… | |
462 | or Carp::croak "required option 'pid' is missing"; |
1009 | or Carp::croak "required option 'pid' is missing"; |
463 | |
1010 | |
464 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
1011 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
465 | |
1012 | |
466 | unless ($WNOHANG) { |
1013 | unless ($WNOHANG) { |
467 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
1014 | $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; |
468 | } |
1015 | } |
469 | |
1016 | |
470 | unless ($CHLD_W) { |
1017 | unless ($CHLD_W) { |
471 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
1018 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
472 | # child could be a zombie already, so make at least one round |
1019 | # child could be a zombie already, so make at least one round |
… | |
… | |
483 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
1030 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
484 | |
1031 | |
485 | undef $CHLD_W unless keys %PID_CB; |
1032 | undef $CHLD_W unless keys %PID_CB; |
486 | } |
1033 | } |
487 | |
1034 | |
|
|
1035 | package AnyEvent::CondVar; |
|
|
1036 | |
|
|
1037 | our @ISA = AnyEvent::CondVar::Base::; |
|
|
1038 | |
|
|
1039 | package AnyEvent::CondVar::Base; |
|
|
1040 | |
|
|
1041 | use overload |
|
|
1042 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
|
|
1043 | fallback => 1; |
|
|
1044 | |
|
|
1045 | sub _send { |
|
|
1046 | # nop |
|
|
1047 | } |
|
|
1048 | |
|
|
1049 | sub send { |
|
|
1050 | my $cv = shift; |
|
|
1051 | $cv->{_ae_sent} = [@_]; |
|
|
1052 | (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb}; |
|
|
1053 | $cv->_send; |
|
|
1054 | } |
|
|
1055 | |
|
|
1056 | sub croak { |
|
|
1057 | $_[0]{_ae_croak} = $_[1]; |
|
|
1058 | $_[0]->send; |
|
|
1059 | } |
|
|
1060 | |
|
|
1061 | sub ready { |
|
|
1062 | $_[0]{_ae_sent} |
|
|
1063 | } |
|
|
1064 | |
|
|
1065 | sub _wait { |
|
|
1066 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
1067 | } |
|
|
1068 | |
|
|
1069 | sub recv { |
|
|
1070 | $_[0]->_wait; |
|
|
1071 | |
|
|
1072 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
1073 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
1074 | } |
|
|
1075 | |
|
|
1076 | sub cb { |
|
|
1077 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
1078 | $_[0]{_ae_cb} |
|
|
1079 | } |
|
|
1080 | |
|
|
1081 | sub begin { |
|
|
1082 | ++$_[0]{_ae_counter}; |
|
|
1083 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
1084 | } |
|
|
1085 | |
|
|
1086 | sub end { |
|
|
1087 | return if --$_[0]{_ae_counter}; |
|
|
1088 | &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } }; |
|
|
1089 | } |
|
|
1090 | |
|
|
1091 | # undocumented/compatibility with pre-3.4 |
|
|
1092 | *broadcast = \&send; |
|
|
1093 | *wait = \&_wait; |
|
|
1094 | |
488 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1095 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
1096 | |
|
|
1097 | This is an advanced topic that you do not normally need to use AnyEvent in |
|
|
1098 | a module. This section is only of use to event loop authors who want to |
|
|
1099 | provide AnyEvent compatibility. |
489 | |
1100 | |
490 | If you need to support another event library which isn't directly |
1101 | If you need to support another event library which isn't directly |
491 | supported by AnyEvent, you can supply your own interface to it by |
1102 | supported by AnyEvent, you can supply your own interface to it by |
492 | pushing, before the first watcher gets created, the package name of |
1103 | pushing, before the first watcher gets created, the package name of |
493 | the event module and the package name of the interface to use onto |
1104 | the event module and the package name of the interface to use onto |
494 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
1105 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
495 | AnyEvent. |
1106 | AnyEvent, so it is reasonably cheap. |
496 | |
1107 | |
497 | Example: |
1108 | Example: |
498 | |
1109 | |
499 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
1110 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
500 | |
1111 | |
501 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
1112 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
502 | package/class when it finds the C<urxvt> package/module is loaded. When |
1113 | package/class when it finds the C<urxvt> package/module is already loaded. |
|
|
1114 | |
503 | AnyEvent is loaded and asked to find a suitable event model, it will |
1115 | When AnyEvent is loaded and asked to find a suitable event model, it |
504 | first check for the presence of urxvt. |
1116 | will first check for the presence of urxvt by trying to C<use> the |
|
|
1117 | C<urxvt::anyevent> module. |
505 | |
1118 | |
506 | The class should provide implementations for all watcher types (see |
1119 | The class should provide implementations for all watcher types. See |
507 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
1120 | L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code) |
508 | (Source code) and so on for actual examples, use C<perldoc -m |
1121 | and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to |
509 | AnyEvent::Impl::Glib> to see the sources). |
1122 | see the sources. |
510 | |
1123 | |
|
|
1124 | If you don't provide C<signal> and C<child> watchers than AnyEvent will |
|
|
1125 | provide suitable (hopefully) replacements. |
|
|
1126 | |
511 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
1127 | The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
512 | uses the above line as-is. An interface isn't included in AnyEvent |
1128 | terminal emulator uses the above line as-is. An interface isn't included |
513 | because it doesn't make sense outside the embedded interpreter inside |
1129 | in AnyEvent because it doesn't make sense outside the embedded interpreter |
514 | I<rxvt-unicode>, and it is updated and maintained as part of the |
1130 | inside I<rxvt-unicode>, and it is updated and maintained as part of the |
515 | I<rxvt-unicode> distribution. |
1131 | I<rxvt-unicode> distribution. |
516 | |
1132 | |
517 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
1133 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
518 | condition variables: code blocking while waiting for a condition will |
1134 | condition variables: code blocking while waiting for a condition will |
519 | C<die>. This still works with most modules/usages, and blocking calls must |
1135 | C<die>. This still works with most modules/usages, and blocking calls must |
520 | not be in an interactive application, so it makes sense. |
1136 | not be done in an interactive application, so it makes sense. |
521 | |
1137 | |
522 | =head1 ENVIRONMENT VARIABLES |
1138 | =head1 ENVIRONMENT VARIABLES |
523 | |
1139 | |
524 | The following environment variables are used by this module: |
1140 | The following environment variables are used by this module: |
525 | |
1141 | |
526 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
1142 | =over 4 |
527 | model gets used. |
|
|
528 | |
1143 | |
|
|
1144 | =item C<PERL_ANYEVENT_VERBOSE> |
|
|
1145 | |
|
|
1146 | By default, AnyEvent will be completely silent except in fatal |
|
|
1147 | conditions. You can set this environment variable to make AnyEvent more |
|
|
1148 | talkative. |
|
|
1149 | |
|
|
1150 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
|
|
1151 | conditions, such as not being able to load the event model specified by |
|
|
1152 | C<PERL_ANYEVENT_MODEL>. |
|
|
1153 | |
|
|
1154 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
|
|
1155 | model it chooses. |
|
|
1156 | |
|
|
1157 | =item C<PERL_ANYEVENT_MODEL> |
|
|
1158 | |
|
|
1159 | This can be used to specify the event model to be used by AnyEvent, before |
|
|
1160 | auto detection and -probing kicks in. It must be a string consisting |
|
|
1161 | entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended |
|
|
1162 | and the resulting module name is loaded and if the load was successful, |
|
|
1163 | used as event model. If it fails to load AnyEvent will proceed with |
|
|
1164 | auto detection and -probing. |
|
|
1165 | |
|
|
1166 | This functionality might change in future versions. |
|
|
1167 | |
|
|
1168 | For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you |
|
|
1169 | could start your program like this: |
|
|
1170 | |
|
|
1171 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
1172 | |
|
|
1173 | =item C<PERL_ANYEVENT_PROTOCOLS> |
|
|
1174 | |
|
|
1175 | Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences |
|
|
1176 | for IPv4 or IPv6. The default is unspecified (and might change, or be the result |
|
|
1177 | of auto probing). |
|
|
1178 | |
|
|
1179 | Must be set to a comma-separated list of protocols or address families, |
|
|
1180 | current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be |
|
|
1181 | used, and preference will be given to protocols mentioned earlier in the |
|
|
1182 | list. |
|
|
1183 | |
|
|
1184 | This variable can effectively be used for denial-of-service attacks |
|
|
1185 | against local programs (e.g. when setuid), although the impact is likely |
|
|
1186 | small, as the program has to handle connection errors already- |
|
|
1187 | |
|
|
1188 | Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, |
|
|
1189 | but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> |
|
|
1190 | - only support IPv4, never try to resolve or contact IPv6 |
|
|
1191 | addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or |
|
|
1192 | IPv6, but prefer IPv6 over IPv4. |
|
|
1193 | |
|
|
1194 | =item C<PERL_ANYEVENT_EDNS0> |
|
|
1195 | |
|
|
1196 | Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension |
|
|
1197 | for DNS. This extension is generally useful to reduce DNS traffic, but |
|
|
1198 | some (broken) firewalls drop such DNS packets, which is why it is off by |
|
|
1199 | default. |
|
|
1200 | |
|
|
1201 | Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce |
|
|
1202 | EDNS0 in its DNS requests. |
|
|
1203 | |
|
|
1204 | =item C<PERL_ANYEVENT_MAX_FORKS> |
|
|
1205 | |
|
|
1206 | The maximum number of child processes that C<AnyEvent::Util::fork_call> |
|
|
1207 | will create in parallel. |
|
|
1208 | |
|
|
1209 | =back |
|
|
1210 | |
529 | =head1 EXAMPLE |
1211 | =head1 EXAMPLE PROGRAM |
530 | |
1212 | |
531 | The following program uses an io watcher to read data from stdin, a timer |
1213 | The following program uses an I/O watcher to read data from STDIN, a timer |
532 | to display a message once per second, and a condvar to exit the program |
1214 | to display a message once per second, and a condition variable to quit the |
533 | when the user enters quit: |
1215 | program when the user enters quit: |
534 | |
1216 | |
535 | use AnyEvent; |
1217 | use AnyEvent; |
536 | |
1218 | |
537 | my $cv = AnyEvent->condvar; |
1219 | my $cv = AnyEvent->condvar; |
538 | |
1220 | |
539 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
1221 | my $io_watcher = AnyEvent->io ( |
|
|
1222 | fh => \*STDIN, |
|
|
1223 | poll => 'r', |
|
|
1224 | cb => sub { |
540 | warn "io event <$_[0]>\n"; # will always output <r> |
1225 | warn "io event <$_[0]>\n"; # will always output <r> |
541 | chomp (my $input = <STDIN>); # read a line |
1226 | chomp (my $input = <STDIN>); # read a line |
542 | warn "read: $input\n"; # output what has been read |
1227 | warn "read: $input\n"; # output what has been read |
543 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
1228 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
|
|
1229 | }, |
544 | }); |
1230 | ); |
545 | |
1231 | |
546 | my $time_watcher; # can only be used once |
1232 | my $time_watcher; # can only be used once |
547 | |
1233 | |
548 | sub new_timer { |
1234 | sub new_timer { |
549 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1235 | $timer = AnyEvent->timer (after => 1, cb => sub { |
… | |
… | |
552 | }); |
1238 | }); |
553 | } |
1239 | } |
554 | |
1240 | |
555 | new_timer; # create first timer |
1241 | new_timer; # create first timer |
556 | |
1242 | |
557 | $cv->wait; # wait until user enters /^q/i |
1243 | $cv->recv; # wait until user enters /^q/i |
558 | |
1244 | |
559 | =head1 REAL-WORLD EXAMPLE |
1245 | =head1 REAL-WORLD EXAMPLE |
560 | |
1246 | |
561 | Consider the L<Net::FCP> module. It features (among others) the following |
1247 | Consider the L<Net::FCP> module. It features (among others) the following |
562 | API calls, which are to freenet what HTTP GET requests are to http: |
1248 | API calls, which are to freenet what HTTP GET requests are to http: |
… | |
… | |
612 | syswrite $txn->{fh}, $txn->{request} |
1298 | syswrite $txn->{fh}, $txn->{request} |
613 | or die "connection or write error"; |
1299 | or die "connection or write error"; |
614 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
1300 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
615 | |
1301 | |
616 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
1302 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
617 | result and signals any possible waiters that the request ahs finished: |
1303 | result and signals any possible waiters that the request has finished: |
618 | |
1304 | |
619 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
1305 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
620 | |
1306 | |
621 | if (end-of-file or data complete) { |
1307 | if (end-of-file or data complete) { |
622 | $txn->{result} = $txn->{buf}; |
1308 | $txn->{result} = $txn->{buf}; |
623 | $txn->{finished}->broadcast; |
1309 | $txn->{finished}->send; |
624 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
1310 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
625 | } |
1311 | } |
626 | |
1312 | |
627 | The C<result> method, finally, just waits for the finished signal (if the |
1313 | The C<result> method, finally, just waits for the finished signal (if the |
628 | request was already finished, it doesn't wait, of course, and returns the |
1314 | request was already finished, it doesn't wait, of course, and returns the |
629 | data: |
1315 | data: |
630 | |
1316 | |
631 | $txn->{finished}->wait; |
1317 | $txn->{finished}->recv; |
632 | return $txn->{result}; |
1318 | return $txn->{result}; |
633 | |
1319 | |
634 | The actual code goes further and collects all errors (C<die>s, exceptions) |
1320 | The actual code goes further and collects all errors (C<die>s, exceptions) |
635 | that occured during request processing. The C<result> method detects |
1321 | that occurred during request processing. The C<result> method detects |
636 | wether an exception as thrown (it is stored inside the $txn object) |
1322 | whether an exception as thrown (it is stored inside the $txn object) |
637 | and just throws the exception, which means connection errors and other |
1323 | and just throws the exception, which means connection errors and other |
638 | problems get reported tot he code that tries to use the result, not in a |
1324 | problems get reported tot he code that tries to use the result, not in a |
639 | random callback. |
1325 | random callback. |
640 | |
1326 | |
641 | All of this enables the following usage styles: |
1327 | All of this enables the following usage styles: |
… | |
… | |
671 | |
1357 | |
672 | my $quit = AnyEvent->condvar; |
1358 | my $quit = AnyEvent->condvar; |
673 | |
1359 | |
674 | $fcp->txn_client_get ($url)->cb (sub { |
1360 | $fcp->txn_client_get ($url)->cb (sub { |
675 | ... |
1361 | ... |
676 | $quit->broadcast; |
1362 | $quit->send; |
677 | }); |
1363 | }); |
678 | |
1364 | |
679 | $quit->wait; |
1365 | $quit->recv; |
|
|
1366 | |
|
|
1367 | |
|
|
1368 | =head1 BENCHMARKS |
|
|
1369 | |
|
|
1370 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
1371 | over the event loops themselves and to give you an impression of the speed |
|
|
1372 | of various event loops I prepared some benchmarks. |
|
|
1373 | |
|
|
1374 | =head2 BENCHMARKING ANYEVENT OVERHEAD |
|
|
1375 | |
|
|
1376 | Here is a benchmark of various supported event models used natively and |
|
|
1377 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
|
|
1378 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
1379 | which it is), lets them fire exactly once and destroys them again. |
|
|
1380 | |
|
|
1381 | Source code for this benchmark is found as F<eg/bench> in the AnyEvent |
|
|
1382 | distribution. |
|
|
1383 | |
|
|
1384 | =head3 Explanation of the columns |
|
|
1385 | |
|
|
1386 | I<watcher> is the number of event watchers created/destroyed. Since |
|
|
1387 | different event models feature vastly different performances, each event |
|
|
1388 | loop was given a number of watchers so that overall runtime is acceptable |
|
|
1389 | and similar between tested event loop (and keep them from crashing): Glib |
|
|
1390 | would probably take thousands of years if asked to process the same number |
|
|
1391 | of watchers as EV in this benchmark. |
|
|
1392 | |
|
|
1393 | I<bytes> is the number of bytes (as measured by the resident set size, |
|
|
1394 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
1395 | and Perl-based overheads. |
|
|
1396 | |
|
|
1397 | I<create> is the time, in microseconds (millionths of seconds), that it |
|
|
1398 | takes to create a single watcher. The callback is a closure shared between |
|
|
1399 | all watchers, to avoid adding memory overhead. That means closure creation |
|
|
1400 | and memory usage is not included in the figures. |
|
|
1401 | |
|
|
1402 | I<invoke> is the time, in microseconds, used to invoke a simple |
|
|
1403 | callback. The callback simply counts down a Perl variable and after it was |
|
|
1404 | invoked "watcher" times, it would C<< ->send >> a condvar once to |
|
|
1405 | signal the end of this phase. |
|
|
1406 | |
|
|
1407 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
|
|
1408 | watcher. |
|
|
1409 | |
|
|
1410 | =head3 Results |
|
|
1411 | |
|
|
1412 | name watchers bytes create invoke destroy comment |
|
|
1413 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
1414 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
1415 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
1416 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
1417 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
1418 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
1419 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
1420 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
1421 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
1422 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
1423 | |
|
|
1424 | =head3 Discussion |
|
|
1425 | |
|
|
1426 | The benchmark does I<not> measure scalability of the event loop very |
|
|
1427 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
1428 | can never compete with an event loop that uses epoll when the number of |
|
|
1429 | file descriptors grows high. In this benchmark, all events become ready at |
|
|
1430 | the same time, so select/poll-based implementations get an unnatural speed |
|
|
1431 | boost. |
|
|
1432 | |
|
|
1433 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1434 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1435 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1436 | higher number of watchers at a disadvantage. |
|
|
1437 | |
|
|
1438 | To put the range of results into perspective, consider that on the |
|
|
1439 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1440 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1441 | cycles with POE. |
|
|
1442 | |
|
|
1443 | C<EV> is the sole leader regarding speed and memory use, which are both |
|
|
1444 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
1445 | far less memory than any other event loop and is still faster than Event |
|
|
1446 | natively. |
|
|
1447 | |
|
|
1448 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
1449 | constant timeout and the use of a single fd hit optimisations in the perl |
|
|
1450 | interpreter and the backend itself). Nevertheless this shows that it |
|
|
1451 | adds very little overhead in itself. Like any select-based backend its |
|
|
1452 | performance becomes really bad with lots of file descriptors (and few of |
|
|
1453 | them active), of course, but this was not subject of this benchmark. |
|
|
1454 | |
|
|
1455 | The C<Event> module has a relatively high setup and callback invocation |
|
|
1456 | cost, but overall scores in on the third place. |
|
|
1457 | |
|
|
1458 | C<Glib>'s memory usage is quite a bit higher, but it features a |
|
|
1459 | faster callback invocation and overall ends up in the same class as |
|
|
1460 | C<Event>. However, Glib scales extremely badly, doubling the number of |
|
|
1461 | watchers increases the processing time by more than a factor of four, |
|
|
1462 | making it completely unusable when using larger numbers of watchers |
|
|
1463 | (note that only a single file descriptor was used in the benchmark, so |
|
|
1464 | inefficiencies of C<poll> do not account for this). |
|
|
1465 | |
|
|
1466 | The C<Tk> adaptor works relatively well. The fact that it crashes with |
|
|
1467 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
1468 | precedence over speed. Nevertheless, its performance is surprising, as the |
|
|
1469 | file descriptor is dup()ed for each watcher. This shows that the dup() |
|
|
1470 | employed by some adaptors is not a big performance issue (it does incur a |
|
|
1471 | hidden memory cost inside the kernel which is not reflected in the figures |
|
|
1472 | above). |
|
|
1473 | |
|
|
1474 | C<POE>, regardless of underlying event loop (whether using its pure perl |
|
|
1475 | select-based backend or the Event module, the POE-EV backend couldn't |
|
|
1476 | be tested because it wasn't working) shows abysmal performance and |
|
|
1477 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
|
|
1478 | as EV watchers, and 10 times as much memory as Event (the high memory |
|
|
1479 | requirements are caused by requiring a session for each watcher). Watcher |
|
|
1480 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1481 | implementation. |
|
|
1482 | |
|
|
1483 | The design of the POE adaptor class in AnyEvent can not really account |
|
|
1484 | for the performance issues, though, as session creation overhead is |
|
|
1485 | small compared to execution of the state machine, which is coded pretty |
|
|
1486 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1487 | using multiple sessions is not a good approach, especially regarding |
|
|
1488 | memory usage, even the author of POE could not come up with a faster |
|
|
1489 | design). |
|
|
1490 | |
|
|
1491 | =head3 Summary |
|
|
1492 | |
|
|
1493 | =over 4 |
|
|
1494 | |
|
|
1495 | =item * Using EV through AnyEvent is faster than any other event loop |
|
|
1496 | (even when used without AnyEvent), but most event loops have acceptable |
|
|
1497 | performance with or without AnyEvent. |
|
|
1498 | |
|
|
1499 | =item * The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
1500 | the actual event loop, only with extremely fast event loops such as EV |
|
|
1501 | adds AnyEvent significant overhead. |
|
|
1502 | |
|
|
1503 | =item * You should avoid POE like the plague if you want performance or |
|
|
1504 | reasonable memory usage. |
|
|
1505 | |
|
|
1506 | =back |
|
|
1507 | |
|
|
1508 | =head2 BENCHMARKING THE LARGE SERVER CASE |
|
|
1509 | |
|
|
1510 | This benchmark actually benchmarks the event loop itself. It works by |
|
|
1511 | creating a number of "servers": each server consists of a socket pair, a |
|
|
1512 | timeout watcher that gets reset on activity (but never fires), and an I/O |
|
|
1513 | watcher waiting for input on one side of the socket. Each time the socket |
|
|
1514 | watcher reads a byte it will write that byte to a random other "server". |
|
|
1515 | |
|
|
1516 | The effect is that there will be a lot of I/O watchers, only part of which |
|
|
1517 | are active at any one point (so there is a constant number of active |
|
|
1518 | fds for each loop iteration, but which fds these are is random). The |
|
|
1519 | timeout is reset each time something is read because that reflects how |
|
|
1520 | most timeouts work (and puts extra pressure on the event loops). |
|
|
1521 | |
|
|
1522 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 |
|
|
1523 | (1%) are active. This mirrors the activity of large servers with many |
|
|
1524 | connections, most of which are idle at any one point in time. |
|
|
1525 | |
|
|
1526 | Source code for this benchmark is found as F<eg/bench2> in the AnyEvent |
|
|
1527 | distribution. |
|
|
1528 | |
|
|
1529 | =head3 Explanation of the columns |
|
|
1530 | |
|
|
1531 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
|
|
1532 | each server has a read and write socket end). |
|
|
1533 | |
|
|
1534 | I<create> is the time it takes to create a socket pair (which is |
|
|
1535 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
1536 | |
|
|
1537 | I<request>, the most important value, is the time it takes to handle a |
|
|
1538 | single "request", that is, reading the token from the pipe and forwarding |
|
|
1539 | it to another server. This includes deleting the old timeout and creating |
|
|
1540 | a new one that moves the timeout into the future. |
|
|
1541 | |
|
|
1542 | =head3 Results |
|
|
1543 | |
|
|
1544 | name sockets create request |
|
|
1545 | EV 20000 69.01 11.16 |
|
|
1546 | Perl 20000 73.32 35.87 |
|
|
1547 | Event 20000 212.62 257.32 |
|
|
1548 | Glib 20000 651.16 1896.30 |
|
|
1549 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
1550 | |
|
|
1551 | =head3 Discussion |
|
|
1552 | |
|
|
1553 | This benchmark I<does> measure scalability and overall performance of the |
|
|
1554 | particular event loop. |
|
|
1555 | |
|
|
1556 | EV is again fastest. Since it is using epoll on my system, the setup time |
|
|
1557 | is relatively high, though. |
|
|
1558 | |
|
|
1559 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
1560 | loops Event and Glib. |
|
|
1561 | |
|
|
1562 | Event suffers from high setup time as well (look at its code and you will |
|
|
1563 | understand why). Callback invocation also has a high overhead compared to |
|
|
1564 | the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event |
|
|
1565 | uses select or poll in basically all documented configurations. |
|
|
1566 | |
|
|
1567 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
1568 | clearly fails to perform with many filehandles or in busy servers. |
|
|
1569 | |
|
|
1570 | POE is still completely out of the picture, taking over 1000 times as long |
|
|
1571 | as EV, and over 100 times as long as the Perl implementation, even though |
|
|
1572 | it uses a C-based event loop in this case. |
|
|
1573 | |
|
|
1574 | =head3 Summary |
|
|
1575 | |
|
|
1576 | =over 4 |
|
|
1577 | |
|
|
1578 | =item * The pure perl implementation performs extremely well. |
|
|
1579 | |
|
|
1580 | =item * Avoid Glib or POE in large projects where performance matters. |
|
|
1581 | |
|
|
1582 | =back |
|
|
1583 | |
|
|
1584 | =head2 BENCHMARKING SMALL SERVERS |
|
|
1585 | |
|
|
1586 | While event loops should scale (and select-based ones do not...) even to |
|
|
1587 | large servers, most programs we (or I :) actually write have only a few |
|
|
1588 | I/O watchers. |
|
|
1589 | |
|
|
1590 | In this benchmark, I use the same benchmark program as in the large server |
|
|
1591 | case, but it uses only eight "servers", of which three are active at any |
|
|
1592 | one time. This should reflect performance for a small server relatively |
|
|
1593 | well. |
|
|
1594 | |
|
|
1595 | The columns are identical to the previous table. |
|
|
1596 | |
|
|
1597 | =head3 Results |
|
|
1598 | |
|
|
1599 | name sockets create request |
|
|
1600 | EV 16 20.00 6.54 |
|
|
1601 | Perl 16 25.75 12.62 |
|
|
1602 | Event 16 81.27 35.86 |
|
|
1603 | Glib 16 32.63 15.48 |
|
|
1604 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
1605 | |
|
|
1606 | =head3 Discussion |
|
|
1607 | |
|
|
1608 | The benchmark tries to test the performance of a typical small |
|
|
1609 | server. While knowing how various event loops perform is interesting, keep |
|
|
1610 | in mind that their overhead in this case is usually not as important, due |
|
|
1611 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1612 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1613 | them). |
|
|
1614 | |
|
|
1615 | EV is again fastest. |
|
|
1616 | |
|
|
1617 | Perl again comes second. It is noticeably faster than the C-based event |
|
|
1618 | loops Event and Glib, although the difference is too small to really |
|
|
1619 | matter. |
|
|
1620 | |
|
|
1621 | POE also performs much better in this case, but is is still far behind the |
|
|
1622 | others. |
|
|
1623 | |
|
|
1624 | =head3 Summary |
|
|
1625 | |
|
|
1626 | =over 4 |
|
|
1627 | |
|
|
1628 | =item * C-based event loops perform very well with small number of |
|
|
1629 | watchers, as the management overhead dominates. |
|
|
1630 | |
|
|
1631 | =back |
|
|
1632 | |
|
|
1633 | |
|
|
1634 | =head1 FORK |
|
|
1635 | |
|
|
1636 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
1637 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1638 | calls. Only L<EV> is fully fork-aware. |
|
|
1639 | |
|
|
1640 | If you have to fork, you must either do so I<before> creating your first |
|
|
1641 | watcher OR you must not use AnyEvent at all in the child. |
|
|
1642 | |
|
|
1643 | |
|
|
1644 | =head1 SECURITY CONSIDERATIONS |
|
|
1645 | |
|
|
1646 | AnyEvent can be forced to load any event model via |
|
|
1647 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
|
|
1648 | execute arbitrary code or directly gain access, it can easily be used to |
|
|
1649 | make the program hang or malfunction in subtle ways, as AnyEvent watchers |
|
|
1650 | will not be active when the program uses a different event model than |
|
|
1651 | specified in the variable. |
|
|
1652 | |
|
|
1653 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
1654 | before the first watcher gets created, e.g. with a C<BEGIN> block: |
|
|
1655 | |
|
|
1656 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
1657 | |
|
|
1658 | use AnyEvent; |
|
|
1659 | |
|
|
1660 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1661 | be used to probe what backend is used and gain other information (which is |
|
|
1662 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
|
|
1663 | |
680 | |
1664 | |
681 | =head1 SEE ALSO |
1665 | =head1 SEE ALSO |
682 | |
1666 | |
683 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1667 | Utility functions: L<AnyEvent::Util>. |
684 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
|
|
685 | |
1668 | |
686 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
1669 | Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, |
|
|
1670 | L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. |
|
|
1671 | |
687 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
1672 | Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, |
688 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
1673 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, |
|
|
1674 | L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, |
|
|
1675 | L<AnyEvent::Impl::POE>. |
689 | |
1676 | |
|
|
1677 | Non-blocking file handles, sockets, TCP clients and |
|
|
1678 | servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. |
|
|
1679 | |
|
|
1680 | Asynchronous DNS: L<AnyEvent::DNS>. |
|
|
1681 | |
|
|
1682 | Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, |
|
|
1683 | |
690 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
1684 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. |
691 | |
1685 | |
692 | =head1 |
1686 | |
|
|
1687 | =head1 AUTHOR |
|
|
1688 | |
|
|
1689 | Marc Lehmann <schmorp@schmorp.de> |
|
|
1690 | http://home.schmorp.de/ |
693 | |
1691 | |
694 | =cut |
1692 | =cut |
695 | |
1693 | |
696 | 1 |
1694 | 1 |
697 | |
1695 | |