| 1 | =head1 NAME |
1 | =head1 NAME |
| 2 | |
2 | |
| 3 | AnyEvent - ??? |
3 | AnyEvent - provide framework for multiple event loops |
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4 | |
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5 | EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl - various supported event loops |
| 4 | |
6 | |
| 5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
| 6 | |
8 | |
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9 | use AnyEvent; |
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10 | |
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11 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
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12 | ... |
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13 | }); |
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14 | |
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15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
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16 | ... |
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17 | }); |
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18 | |
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19 | my $w = AnyEvent->condvar; # stores wether a condition was flagged |
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20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
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21 | $w->broadcast; # wake up current and all future wait's |
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22 | |
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23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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24 | |
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25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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26 | nowadays. So what is different about AnyEvent? |
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27 | |
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28 | Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of |
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29 | policy> and AnyEvent is I<small and efficient>. |
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30 | |
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31 | First and foremost, I<AnyEvent is not an event model> itself, it only |
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32 | interfaces to whatever event model the main program happens to use in a |
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33 | pragmatic way. For event models and certain classes of immortals alike, |
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34 | the statement "there can only be one" is a bitter reality, and AnyEvent |
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35 | helps hiding the differences. |
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36 | |
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37 | The goal of AnyEvent is to offer module authors the ability to do event |
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38 | programming (waiting for I/O or timer events) without subscribing to a |
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39 | religion, a way of living, and most importantly: without forcing your |
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40 | module users into the same thing by forcing them to use the same event |
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41 | model you use. |
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42 | |
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43 | For modules like POE or IO::Async (which is actually doing all I/O |
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44 | I<synchronously>...), using them in your module is like joining a |
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45 | cult: After you joined, you are dependent on them and you cannot use |
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46 | anything else, as it is simply incompatible to everything that isn't |
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47 | itself. |
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48 | |
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49 | AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk |
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50 | works fine etc. etc. but none of these work together with the rest: POE |
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51 | + IO::Async? no go. Tk + Event? no go. If your module uses one of |
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52 | those, every user of your module has to use it, too. If your module |
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53 | uses AnyEvent, it works transparently with all event models it supports |
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54 | (including stuff like POE and IO::Async). |
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55 | |
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56 | In addition of being free of having to use I<the one and only true event |
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57 | model>, AnyEvent also is free of bloat and policy: with POE or similar |
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58 | modules, you get an enourmous amount of code and strict rules you have |
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59 | to follow. AnyEvent, on the other hand, is lean and to the point by only |
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60 | offering the functionality that is useful, in as thin as a wrapper as |
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61 | technically possible. |
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62 | |
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63 | Of course, if you want lots of policy (this can arguably be somewhat |
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64 | useful) and you want to force your users to use the one and only event |
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65 | model, you should I<not> use this module. |
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66 | |
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67 | |
| 7 | =head1 DESCRIPTION |
68 | =head1 DESCRIPTION |
| 8 | |
69 | |
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70 | L<AnyEvent> provides an identical interface to multiple event loops. This |
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71 | allows module authors to utilise an event loop without forcing module |
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72 | users to use the same event loop (as only a single event loop can coexist |
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73 | peacefully at any one time). |
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74 | |
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75 | The interface itself is vaguely similar but not identical to the Event |
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76 | module. |
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77 | |
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78 | On the first call of any method, the module tries to detect the currently |
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79 | loaded event loop by probing wether any of the following modules is |
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80 | loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, L<Event>, L<Glib>, L<Tk>. The |
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81 | first one found is used. If none are found, the module tries to load these |
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82 | modules in the order given. The first one that could be successfully |
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83 | loaded will be used. If still none could be found, AnyEvent will fall back |
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84 | to a pure-perl event loop, which is also not very efficient. |
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85 | |
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86 | Because AnyEvent first checks for modules that are already loaded, loading |
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87 | an Event model explicitly before first using AnyEvent will likely make |
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88 | that model the default. For example: |
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89 | |
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90 | use Tk; |
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91 | use AnyEvent; |
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92 | |
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93 | # .. AnyEvent will likely default to Tk |
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94 | |
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95 | The pure-perl implementation of AnyEvent is called |
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96 | C<AnyEvent::Impl::Perl>. Like other event modules you can load it |
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97 | explicitly. |
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98 | |
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99 | =head1 WATCHERS |
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100 | |
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101 | AnyEvent has the central concept of a I<watcher>, which is an object that |
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102 | stores relevant data for each kind of event you are waiting for, such as |
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103 | the callback to call, the filehandle to watch, etc. |
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104 | |
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105 | These watchers are normal Perl objects with normal Perl lifetime. After |
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106 | creating a watcher it will immediately "watch" for events and invoke |
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107 | the callback. To disable the watcher you have to destroy it (e.g. by |
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108 | setting the variable that stores it to C<undef> or otherwise deleting all |
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109 | references to it). |
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110 | |
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111 | All watchers are created by calling a method on the C<AnyEvent> class. |
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112 | |
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113 | =head2 IO WATCHERS |
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114 | |
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115 | You can create I/O watcher by calling the C<< AnyEvent->io >> method with |
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116 | the following mandatory arguments: |
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117 | |
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118 | C<fh> the Perl I<filehandle> (not filedescriptor) to watch for |
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119 | events. C<poll> must be a string that is either C<r> or C<w>, that creates |
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120 | a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback |
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121 | to invoke everytime the filehandle becomes ready. |
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122 | |
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123 | Filehandles will be kept alive, so as long as the watcher exists, the |
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124 | filehandle exists, too. |
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125 | |
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126 | Example: |
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127 | |
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128 | # wait for readability of STDIN, then read a line and disable the watcher |
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129 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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130 | chomp (my $input = <STDIN>); |
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131 | warn "read: $input\n"; |
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132 | undef $w; |
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133 | }); |
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134 | |
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135 | =head2 TIME WATCHERS |
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136 | |
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137 | You can create a time watcher by calling the C<< AnyEvent->timer >> |
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138 | method with the following mandatory arguments: |
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139 | |
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140 | C<after> after how many seconds (fractions are supported) should the timer |
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141 | activate. C<cb> the callback to invoke. |
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142 | |
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143 | The timer callback will be invoked at most once: if you want a repeating |
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144 | timer you have to create a new watcher (this is a limitation by both Tk |
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145 | and Glib). |
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146 | |
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147 | Example: |
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148 | |
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149 | # fire an event after 7.7 seconds |
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150 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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151 | warn "timeout\n"; |
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152 | }); |
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153 | |
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154 | # to cancel the timer: |
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155 | undef $w; |
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156 | |
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157 | =head2 CONDITION WATCHERS |
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158 | |
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159 | Condition watchers can be created by calling the C<< AnyEvent->condvar >> |
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160 | method without any arguments. |
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161 | |
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162 | A condition watcher watches for a condition - precisely that the C<< |
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163 | ->broadcast >> method has been called. |
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164 | |
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165 | Note that condition watchers recurse into the event loop - if you have |
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166 | two watchers that call C<< ->wait >> in a round-robbin fashion, you |
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167 | lose. Therefore, condition watchers are good to export to your caller, but |
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168 | you should avoid making a blocking wait, at least in callbacks, as this |
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169 | usually asks for trouble. |
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170 | |
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171 | The watcher has only two methods: |
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172 | |
| 9 | =over 4 |
173 | =over 4 |
| 10 | |
174 | |
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175 | =item $cv->wait |
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176 | |
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177 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
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178 | called on c<$cv>, while servicing other watchers normally. |
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179 | |
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180 | You can only wait once on a condition - additional calls will return |
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181 | immediately. |
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182 | |
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183 | Not all event models support a blocking wait - some die in that case |
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184 | (programs might want to do that so they stay interactive), so I<if you |
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185 | are using this from a module, never require a blocking wait>, but let the |
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186 | caller decide wether the call will block or not (for example, by coupling |
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187 | condition variables with some kind of request results and supporting |
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188 | callbacks so the caller knows that getting the result will not block, |
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189 | while still suppporting blocking waits if the caller so desires). |
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190 | |
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191 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
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192 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
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193 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
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194 | can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event> |
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195 | explicitly support concurrent C<< ->wait >>'s from different coroutines, |
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196 | however). |
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197 | |
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198 | =item $cv->broadcast |
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199 | |
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200 | Flag the condition as ready - a running C<< ->wait >> and all further |
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201 | calls to C<wait> will return after this method has been called. If nobody |
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202 | is waiting the broadcast will be remembered.. |
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203 | |
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204 | Example: |
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205 | |
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206 | # wait till the result is ready |
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207 | my $result_ready = AnyEvent->condvar; |
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208 | |
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209 | # do something such as adding a timer |
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210 | # or socket watcher the calls $result_ready->broadcast |
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211 | # when the "result" is ready. |
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212 | |
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213 | $result_ready->wait; |
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214 | |
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215 | =back |
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216 | |
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217 | =head2 SIGNAL WATCHERS |
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218 | |
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219 | You can listen for signals using a signal watcher, C<signal> is the signal |
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220 | I<name> without any C<SIG> prefix. Multiple signals events can be clumped |
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221 | together into one callback invocation, and callback invocation might or |
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222 | might not be asynchronous. |
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223 | |
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224 | These watchers might use C<%SIG>, so programs overwriting those signals |
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225 | directly will likely not work correctly. |
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226 | |
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227 | Example: exit on SIGINT |
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228 | |
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229 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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230 | |
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231 | =head2 CHILD PROCESS WATCHERS |
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232 | |
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233 | You can also listen for the status of a child process specified by the |
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234 | C<pid> argument (or any child if the pid argument is 0). The watcher will |
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235 | trigger as often as status change for the child are received. This works |
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236 | by installing a signal handler for C<SIGCHLD>. The callback will be called with |
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237 | the pid and exit status (as returned by waitpid). |
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238 | |
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239 | Example: wait for pid 1333 |
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240 | |
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241 | my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); |
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242 | |
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243 | =head1 GLOBALS |
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244 | |
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245 | =over 4 |
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246 | |
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247 | =item $AnyEvent::MODEL |
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248 | |
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249 | Contains C<undef> until the first watcher is being created. Then it |
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250 | contains the event model that is being used, which is the name of the |
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251 | Perl class implementing the model. This class is usually one of the |
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252 | C<AnyEvent::Impl:xxx> modules, but can be any other class in the case |
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253 | AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). |
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254 | |
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255 | The known classes so far are: |
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256 | |
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257 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
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258 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
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259 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
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260 | AnyEvent::Impl::Event based on Event, also second best choice :) |
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261 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
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262 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
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263 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
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264 | |
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265 | =item AnyEvent::detect |
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266 | |
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267 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if |
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268 | necessary. You should only call this function right before you would have |
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269 | created an AnyEvent watcher anyway, that is, very late at runtime. |
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270 | |
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271 | =back |
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272 | |
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273 | =head1 WHAT TO DO IN A MODULE |
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274 | |
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275 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
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276 | freely, but you should not load a specific event module or rely on it. |
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277 | |
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278 | Be careful when you create watchers in the module body - Anyevent will |
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279 | decide which event module to use as soon as the first method is called, so |
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280 | by calling AnyEvent in your module body you force the user of your module |
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281 | to load the event module first. |
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282 | |
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283 | =head1 WHAT TO DO IN THE MAIN PROGRAM |
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284 | |
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285 | There will always be a single main program - the only place that should |
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286 | dictate which event model to use. |
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287 | |
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288 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
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289 | do anything special and let AnyEvent decide which implementation to chose. |
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290 | |
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291 | If the main program relies on a specific event model (for example, in Gtk2 |
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292 | programs you have to rely on either Glib or Glib::Event), you should load |
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293 | it before loading AnyEvent or any module that uses it, generally, as early |
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294 | as possible. The reason is that modules might create watchers when they |
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295 | are loaded, and AnyEvent will decide on the event model to use as soon as |
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296 | it creates watchers, and it might chose the wrong one unless you load the |
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297 | correct one yourself. |
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298 | |
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299 | You can chose to use a rather inefficient pure-perl implementation by |
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300 | loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is |
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301 | generally better. |
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302 | |
| 11 | =cut |
303 | =cut |
| 12 | |
304 | |
| 13 | package AnyEvent; |
305 | package AnyEvent; |
| 14 | |
306 | |
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307 | no warnings; |
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308 | use strict; |
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309 | |
| 15 | use Carp; |
310 | use Carp; |
| 16 | |
311 | |
| 17 | $VERSION = 0.1; |
312 | our $VERSION = '3.1'; |
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313 | our $MODEL; |
| 18 | |
314 | |
| 19 | no warnings; |
315 | our $AUTOLOAD; |
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316 | our @ISA; |
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317 | |
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318 | our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; |
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319 | |
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320 | our @REGISTRY; |
| 20 | |
321 | |
| 21 | my @models = ( |
322 | my @models = ( |
| 22 | [Coro => Coro::Event::], |
323 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
| 23 | [Event => Event::], |
324 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
| 24 | [Glib => Glib::], |
325 | [EV:: => AnyEvent::Impl::EV::], |
| 25 | [Tk => Tk::], |
326 | [Event:: => AnyEvent::Impl::Event::], |
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327 | [Glib:: => AnyEvent::Impl::Glib::], |
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328 | [Tk:: => AnyEvent::Impl::Tk::], |
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329 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
| 26 | ); |
330 | ); |
| 27 | |
331 | |
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332 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
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333 | |
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334 | sub detect() { |
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335 | unless ($MODEL) { |
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336 | no strict 'refs'; |
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337 | |
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338 | # check for already loaded models |
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339 | for (@REGISTRY, @models) { |
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340 | my ($package, $model) = @$_; |
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341 | if (${"$package\::VERSION"} > 0) { |
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342 | if (eval "require $model") { |
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343 | $MODEL = $model; |
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344 | warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1; |
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345 | last; |
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346 | } |
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347 | } |
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348 | } |
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349 | |
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350 | unless ($MODEL) { |
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351 | # try to load a model |
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352 | |
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353 | for (@REGISTRY, @models) { |
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354 | my ($package, $model) = @$_; |
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355 | if (eval "require $package" |
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356 | and ${"$package\::VERSION"} > 0 |
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357 | and eval "require $model") { |
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358 | $MODEL = $model; |
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359 | warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; |
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360 | last; |
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361 | } |
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362 | } |
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363 | |
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364 | $MODEL |
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365 | 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."; |
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366 | } |
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367 | |
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368 | unshift @ISA, $MODEL; |
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369 | push @{"$MODEL\::ISA"}, "AnyEvent::Base"; |
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370 | } |
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371 | |
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372 | $MODEL |
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373 | } |
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374 | |
| 28 | sub AUTOLOAD { |
375 | sub AUTOLOAD { |
| 29 | $AUTOLOAD =~ s/.*://; |
376 | (my $func = $AUTOLOAD) =~ s/.*://; |
| 30 | |
377 | |
| 31 | for (@models) { |
378 | $method{$func} |
| 32 | my ($model, $package) = @$_; |
379 | or croak "$func: not a valid method for AnyEvent objects"; |
| 33 | if (defined ${"$package\::VERSION"}) { |
380 | |
| 34 | $EVENT = "AnyEvent::Impl::$model"; |
381 | detect unless $MODEL; |
| 35 | eval "require $EVENT"; die if $@; |
382 | |
| 36 | goto &{"$EVENT\::$AUTOLOAD"}; |
383 | my $class = shift; |
| 37 | } |
384 | $class->$func (@_); |
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385 | } |
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386 | |
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387 | package AnyEvent::Base; |
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388 | |
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389 | # default implementation for ->condvar, ->wait, ->broadcast |
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390 | |
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391 | sub condvar { |
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392 | bless \my $flag, "AnyEvent::Base::CondVar" |
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393 | } |
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394 | |
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395 | sub AnyEvent::Base::CondVar::broadcast { |
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396 | ${$_[0]}++; |
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397 | } |
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398 | |
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399 | sub AnyEvent::Base::CondVar::wait { |
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400 | AnyEvent->one_event while !${$_[0]}; |
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401 | } |
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402 | |
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403 | # default implementation for ->signal |
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404 | |
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405 | our %SIG_CB; |
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406 | |
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407 | sub signal { |
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408 | my (undef, %arg) = @_; |
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409 | |
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410 | my $signal = uc $arg{signal} |
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411 | or Carp::croak "required option 'signal' is missing"; |
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412 | |
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413 | $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; |
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414 | $SIG{$signal} ||= sub { |
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415 | $_->() for values %{ $SIG_CB{$signal} || {} }; |
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416 | }; |
|
|
417 | |
|
|
418 | bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" |
|
|
419 | } |
|
|
420 | |
|
|
421 | sub AnyEvent::Base::Signal::DESTROY { |
|
|
422 | my ($signal, $cb) = @{$_[0]}; |
|
|
423 | |
|
|
424 | delete $SIG_CB{$signal}{$cb}; |
|
|
425 | |
|
|
426 | $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} }; |
|
|
427 | } |
|
|
428 | |
|
|
429 | # default implementation for ->child |
|
|
430 | |
|
|
431 | our %PID_CB; |
|
|
432 | our $CHLD_W; |
|
|
433 | our $CHLD_DELAY_W; |
|
|
434 | our $PID_IDLE; |
|
|
435 | our $WNOHANG; |
|
|
436 | |
|
|
437 | sub _child_wait { |
|
|
438 | while (0 < (my $pid = waitpid -1, $WNOHANG)) { |
|
|
439 | $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), |
|
|
440 | (values %{ $PID_CB{0} || {} }); |
| 38 | } |
441 | } |
| 39 | |
442 | |
| 40 | for (@models) { |
443 | undef $PID_IDLE; |
| 41 | my ($model, $package) = @$_; |
444 | } |
| 42 | $EVENT = "AnyEvent::Impl::$model"; |
445 | |
| 43 | if (eval "require $EVENT") { |
446 | sub _sigchld { |
| 44 | goto &{"$EVENT\::$AUTOLOAD"}; |
447 | # make sure we deliver these changes "synchronous" with the event loop. |
| 45 | } |
448 | $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub { |
|
|
449 | undef $CHLD_DELAY_W; |
|
|
450 | &_child_wait; |
|
|
451 | }); |
|
|
452 | } |
|
|
453 | |
|
|
454 | sub child { |
|
|
455 | my (undef, %arg) = @_; |
|
|
456 | |
|
|
457 | defined (my $pid = $arg{pid} + 0) |
|
|
458 | or Carp::croak "required option 'pid' is missing"; |
|
|
459 | |
|
|
460 | $PID_CB{$pid}{$arg{cb}} = $arg{cb}; |
|
|
461 | |
|
|
462 | unless ($WNOHANG) { |
|
|
463 | $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; |
| 46 | } |
464 | } |
| 47 | |
465 | |
| 48 | die "No event module selected for AnyEvent and autodetect failed. Install any of these: Coro, Event, Glib or Tk."; |
466 | unless ($CHLD_W) { |
| 49 | } |
467 | $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); |
|
|
468 | # child could be a zombie already, so make at least one round |
|
|
469 | &_sigchld; |
|
|
470 | } |
| 50 | |
471 | |
| 51 | 1; |
472 | bless [$pid, $arg{cb}], "AnyEvent::Base::Child" |
|
|
473 | } |
| 52 | |
474 | |
|
|
475 | sub AnyEvent::Base::Child::DESTROY { |
|
|
476 | my ($pid, $cb) = @{$_[0]}; |
|
|
477 | |
|
|
478 | delete $PID_CB{$pid}{$cb}; |
|
|
479 | delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; |
|
|
480 | |
|
|
481 | undef $CHLD_W unless keys %PID_CB; |
|
|
482 | } |
|
|
483 | |
|
|
484 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
485 | |
|
|
486 | If you need to support another event library which isn't directly |
|
|
487 | supported by AnyEvent, you can supply your own interface to it by |
|
|
488 | pushing, before the first watcher gets created, the package name of |
|
|
489 | the event module and the package name of the interface to use onto |
|
|
490 | C<@AnyEvent::REGISTRY>. You can do that before and even without loading |
|
|
491 | AnyEvent. |
|
|
492 | |
|
|
493 | Example: |
|
|
494 | |
|
|
495 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
496 | |
|
|
497 | This tells AnyEvent to (literally) use the C<urxvt::anyevent::> |
|
|
498 | package/class when it finds the C<urxvt> package/module is loaded. When |
|
|
499 | AnyEvent is loaded and asked to find a suitable event model, it will |
|
|
500 | first check for the presence of urxvt. |
|
|
501 | |
|
|
502 | The class should provide implementations for all watcher types (see |
|
|
503 | L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib> |
|
|
504 | (Source code) and so on for actual examples, use C<perldoc -m |
|
|
505 | AnyEvent::Impl::Glib> to see the sources). |
|
|
506 | |
|
|
507 | The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) |
|
|
508 | uses the above line as-is. An interface isn't included in AnyEvent |
|
|
509 | because it doesn't make sense outside the embedded interpreter inside |
|
|
510 | I<rxvt-unicode>, and it is updated and maintained as part of the |
|
|
511 | I<rxvt-unicode> distribution. |
|
|
512 | |
|
|
513 | I<rxvt-unicode> also cheats a bit by not providing blocking access to |
|
|
514 | condition variables: code blocking while waiting for a condition will |
|
|
515 | C<die>. This still works with most modules/usages, and blocking calls must |
|
|
516 | not be in an interactive application, so it makes sense. |
|
|
517 | |
|
|
518 | =head1 ENVIRONMENT VARIABLES |
|
|
519 | |
|
|
520 | The following environment variables are used by this module: |
|
|
521 | |
|
|
522 | C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event |
|
|
523 | model gets used. |
|
|
524 | |
|
|
525 | =head1 EXAMPLE |
|
|
526 | |
|
|
527 | The following program uses an io watcher to read data from stdin, a timer |
|
|
528 | to display a message once per second, and a condvar to exit the program |
|
|
529 | when the user enters quit: |
|
|
530 | |
|
|
531 | use AnyEvent; |
|
|
532 | |
|
|
533 | my $cv = AnyEvent->condvar; |
|
|
534 | |
|
|
535 | my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
|
|
536 | warn "io event <$_[0]>\n"; # will always output <r> |
|
|
537 | chomp (my $input = <STDIN>); # read a line |
|
|
538 | warn "read: $input\n"; # output what has been read |
|
|
539 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
|
|
540 | }); |
|
|
541 | |
|
|
542 | my $time_watcher; # can only be used once |
|
|
543 | |
|
|
544 | sub new_timer { |
|
|
545 | $timer = AnyEvent->timer (after => 1, cb => sub { |
|
|
546 | warn "timeout\n"; # print 'timeout' about every second |
|
|
547 | &new_timer; # and restart the time |
|
|
548 | }); |
|
|
549 | } |
|
|
550 | |
|
|
551 | new_timer; # create first timer |
|
|
552 | |
|
|
553 | $cv->wait; # wait until user enters /^q/i |
|
|
554 | |
|
|
555 | =head1 REAL-WORLD EXAMPLE |
|
|
556 | |
|
|
557 | Consider the L<Net::FCP> module. It features (among others) the following |
|
|
558 | API calls, which are to freenet what HTTP GET requests are to http: |
|
|
559 | |
|
|
560 | my $data = $fcp->client_get ($url); # blocks |
|
|
561 | |
|
|
562 | my $transaction = $fcp->txn_client_get ($url); # does not block |
|
|
563 | $transaction->cb ( sub { ... } ); # set optional result callback |
|
|
564 | my $data = $transaction->result; # possibly blocks |
|
|
565 | |
|
|
566 | The C<client_get> method works like C<LWP::Simple::get>: it requests the |
|
|
567 | given URL and waits till the data has arrived. It is defined to be: |
|
|
568 | |
|
|
569 | sub client_get { $_[0]->txn_client_get ($_[1])->result } |
|
|
570 | |
|
|
571 | And in fact is automatically generated. This is the blocking API of |
|
|
572 | L<Net::FCP>, and it works as simple as in any other, similar, module. |
|
|
573 | |
|
|
574 | More complicated is C<txn_client_get>: It only creates a transaction |
|
|
575 | (completion, result, ...) object and initiates the transaction. |
|
|
576 | |
|
|
577 | my $txn = bless { }, Net::FCP::Txn::; |
|
|
578 | |
|
|
579 | It also creates a condition variable that is used to signal the completion |
|
|
580 | of the request: |
|
|
581 | |
|
|
582 | $txn->{finished} = AnyAvent->condvar; |
|
|
583 | |
|
|
584 | It then creates a socket in non-blocking mode. |
|
|
585 | |
|
|
586 | socket $txn->{fh}, ...; |
|
|
587 | fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
|
|
588 | connect $txn->{fh}, ... |
|
|
589 | and !$!{EWOULDBLOCK} |
|
|
590 | and !$!{EINPROGRESS} |
|
|
591 | and Carp::croak "unable to connect: $!\n"; |
|
|
592 | |
|
|
593 | Then it creates a write-watcher which gets called whenever an error occurs |
|
|
594 | or the connection succeeds: |
|
|
595 | |
|
|
596 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
|
|
597 | |
|
|
598 | And returns this transaction object. The C<fh_ready_w> callback gets |
|
|
599 | called as soon as the event loop detects that the socket is ready for |
|
|
600 | writing. |
|
|
601 | |
|
|
602 | The C<fh_ready_w> method makes the socket blocking again, writes the |
|
|
603 | request data and replaces the watcher by a read watcher (waiting for reply |
|
|
604 | data). The actual code is more complicated, but that doesn't matter for |
|
|
605 | this example: |
|
|
606 | |
|
|
607 | fcntl $txn->{fh}, F_SETFL, 0; |
|
|
608 | syswrite $txn->{fh}, $txn->{request} |
|
|
609 | or die "connection or write error"; |
|
|
610 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
|
|
611 | |
|
|
612 | Again, C<fh_ready_r> waits till all data has arrived, and then stores the |
|
|
613 | result and signals any possible waiters that the request ahs finished: |
|
|
614 | |
|
|
615 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
|
|
616 | |
|
|
617 | if (end-of-file or data complete) { |
|
|
618 | $txn->{result} = $txn->{buf}; |
|
|
619 | $txn->{finished}->broadcast; |
|
|
620 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
|
|
621 | } |
|
|
622 | |
|
|
623 | The C<result> method, finally, just waits for the finished signal (if the |
|
|
624 | request was already finished, it doesn't wait, of course, and returns the |
|
|
625 | data: |
|
|
626 | |
|
|
627 | $txn->{finished}->wait; |
|
|
628 | return $txn->{result}; |
|
|
629 | |
|
|
630 | The actual code goes further and collects all errors (C<die>s, exceptions) |
|
|
631 | that occured during request processing. The C<result> method detects |
|
|
632 | wether an exception as thrown (it is stored inside the $txn object) |
|
|
633 | and just throws the exception, which means connection errors and other |
|
|
634 | problems get reported tot he code that tries to use the result, not in a |
|
|
635 | random callback. |
|
|
636 | |
|
|
637 | All of this enables the following usage styles: |
|
|
638 | |
|
|
639 | 1. Blocking: |
|
|
640 | |
|
|
641 | my $data = $fcp->client_get ($url); |
|
|
642 | |
|
|
643 | 2. Blocking, but running in parallel: |
|
|
644 | |
|
|
645 | my @datas = map $_->result, |
|
|
646 | map $fcp->txn_client_get ($_), |
|
|
647 | @urls; |
|
|
648 | |
|
|
649 | Both blocking examples work without the module user having to know |
|
|
650 | anything about events. |
|
|
651 | |
|
|
652 | 3a. Event-based in a main program, using any supported event module: |
|
|
653 | |
|
|
654 | use EV; |
|
|
655 | |
|
|
656 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
657 | my $txn = shift; |
|
|
658 | my $data = $txn->result; |
|
|
659 | ... |
|
|
660 | }); |
|
|
661 | |
|
|
662 | EV::loop; |
|
|
663 | |
|
|
664 | 3b. The module user could use AnyEvent, too: |
|
|
665 | |
|
|
666 | use AnyEvent; |
|
|
667 | |
|
|
668 | my $quit = AnyEvent->condvar; |
|
|
669 | |
|
|
670 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
671 | ... |
|
|
672 | $quit->broadcast; |
|
|
673 | }); |
|
|
674 | |
|
|
675 | $quit->wait; |
|
|
676 | |
|
|
677 | =head1 SEE ALSO |
|
|
678 | |
|
|
679 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
|
|
680 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>. |
|
|
681 | |
|
|
682 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
|
|
683 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, |
|
|
684 | L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>. |
|
|
685 | |
|
|
686 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
|
|
687 | |
|
|
688 | =head1 |
|
|
689 | |
|
|
690 | =cut |
|
|
691 | |
|
|
692 | 1 |
|
|
693 | |
