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1 | NAME |
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2 | AnyEvent - provide framework for multiple event loops |
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3 | |
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4 | EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - |
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5 | various supported event loops |
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6 | |
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7 | SYNOPSIS |
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8 | use AnyEvent; |
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9 | |
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10 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { |
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11 | ... |
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12 | }); |
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13 | |
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14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
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15 | ... |
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16 | }); |
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17 | |
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18 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
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19 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
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20 | $w->broadcast; # wake up current and all future wait's |
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21 | |
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22 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
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23 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
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24 | nowadays. So what is different about AnyEvent? |
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25 | |
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26 | Executive Summary: AnyEvent is *compatible*, AnyEvent is *free of |
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27 | policy* and AnyEvent is *small and efficient*. |
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28 | |
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29 | First and foremost, *AnyEvent is not an event model* itself, it only |
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30 | interfaces to whatever event model the main program happens to use in a |
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31 | pragmatic way. For event models and certain classes of immortals alike, |
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32 | the statement "there can only be one" is a bitter reality: In general, |
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33 | only one event loop can be active at the same time in a process. |
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34 | AnyEvent helps hiding the differences between those event loops. |
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35 | |
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36 | The goal of AnyEvent is to offer module authors the ability to do event |
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37 | programming (waiting for I/O or timer events) without subscribing to a |
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38 | religion, a way of living, and most importantly: without forcing your |
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39 | module users into the same thing by forcing them to use the same event |
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40 | model you use. |
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41 | |
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42 | For modules like POE or IO::Async (which is a total misnomer as it is |
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43 | actually doing all I/O *synchronously*...), using them in your module is |
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44 | like joining a cult: After you joined, you are dependent on them and you |
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45 | cannot use anything else, as it is simply incompatible to everything |
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46 | that isn't itself. What's worse, all the potential users of your module |
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47 | are *also* forced to use the same event loop you use. |
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48 | |
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49 | AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works |
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50 | fine. AnyEvent + Tk works fine etc. etc. but none of these work together |
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51 | with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if your |
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52 | module uses one of those, every user of your module has to use it, too. |
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53 | But if your module uses AnyEvent, it works transparently with all event |
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54 | models it supports (including stuff like POE and IO::Async, as long as |
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55 | those use one of the supported event loops. It is trivial to add new |
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56 | event loops to AnyEvent, too, so it is future-proof). |
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57 | |
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58 | In addition to being free of having to use *the one and only true event |
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59 | model*, AnyEvent also is free of bloat and policy: with POE or similar |
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60 | modules, you get an enourmous amount of code and strict rules you have |
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61 | to follow. AnyEvent, on the other hand, is lean and up to the point, by |
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62 | only offering the functionality that is necessary, in as thin as a |
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63 | wrapper as technically possible. |
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64 | |
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65 | Of course, if you want lots of policy (this can arguably be somewhat |
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66 | useful) and you want to force your users to use the one and only event |
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67 | model, you should *not* use this module. |
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68 | |
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69 | DESCRIPTION |
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70 | 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 |
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73 | coexist 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 | During the first call of any watcher-creation method, the module tries |
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79 | to detect the currently loaded event loop by probing whether one of the |
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80 | following modules is already loaded: Coro::EV, Coro::Event, EV, Event, |
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81 | Glib, AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found |
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82 | is used. If none are found, the module tries to load these modules |
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83 | (excluding Tk, Event::Lib, Qt and POE as the pure perl adaptor should |
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84 | always succeed) in the order given. The first one that can be |
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85 | successfully loaded will be used. If, after this, still none could be |
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86 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
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87 | very efficient, but should work everywhere. |
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88 | |
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89 | Because AnyEvent first checks for modules that are already loaded, |
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90 | loading an event model explicitly before first using AnyEvent will |
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91 | likely make that model the default. For example: |
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92 | |
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93 | use Tk; |
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94 | use AnyEvent; |
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95 | |
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96 | # .. AnyEvent will likely default to Tk |
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97 | |
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98 | The *likely* means that, if any module loads another event model and |
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99 | starts using it, all bets are off. Maybe you should tell their authors |
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100 | to use AnyEvent so their modules work together with others seamlessly... |
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101 | |
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102 | The pure-perl implementation of AnyEvent is called |
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103 | "AnyEvent::Impl::Perl". Like other event modules you can load it |
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104 | explicitly. |
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105 | |
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106 | WATCHERS |
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107 | AnyEvent has the central concept of a *watcher*, which is an object that |
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108 | stores relevant data for each kind of event you are waiting for, such as |
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109 | the callback to call, the filehandle to watch, etc. |
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110 | |
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111 | These watchers are normal Perl objects with normal Perl lifetime. After |
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112 | creating a watcher it will immediately "watch" for events and invoke the |
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113 | callback when the event occurs (of course, only when the event model is |
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114 | in control). |
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115 | |
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116 | To disable the watcher you have to destroy it (e.g. by setting the |
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117 | variable you store it in to "undef" or otherwise deleting all references |
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118 | to it). |
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119 | |
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120 | All watchers are created by calling a method on the "AnyEvent" class. |
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121 | |
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122 | Many watchers either are used with "recursion" (repeating timers for |
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123 | example), or need to refer to their watcher object in other ways. |
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124 | |
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125 | An any way to achieve that is this pattern: |
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126 | |
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127 | my $w; $w = AnyEvent->type (arg => value ..., cb => sub { |
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128 | # you can use $w here, for example to undef it |
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129 | undef $w; |
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130 | }); |
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131 | |
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132 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
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133 | my variables are only visible after the statement in which they are |
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134 | declared. |
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135 | |
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136 | I/O WATCHERS |
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137 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
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138 | the following mandatory key-value pairs as arguments: |
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139 | |
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140 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events. |
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141 | "poll" must be a string that is either "r" or "w", which creates a |
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142 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
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143 | is the callback to invoke each time the file handle becomes ready. |
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144 | |
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145 | Although the callback might get passed parameters, their value and |
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146 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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147 | callbacks cannot use arguments passed to I/O watcher callbacks. |
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148 | |
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149 | The I/O watcher might use the underlying file descriptor or a copy of |
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150 | it. You must not close a file handle as long as any watcher is active on |
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151 | the underlying file descriptor. |
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152 | |
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153 | Some event loops issue spurious readyness notifications, so you should |
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154 | always use non-blocking calls when reading/writing from/to your file |
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155 | handles. |
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156 | |
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157 | Example: |
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158 | |
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159 | # wait for readability of STDIN, then read a line and disable the watcher |
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160 | my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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161 | chomp (my $input = <STDIN>); |
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162 | warn "read: $input\n"; |
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163 | undef $w; |
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164 | }); |
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165 | |
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166 | TIME WATCHERS |
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167 | You can create a time watcher by calling the "AnyEvent->timer" method |
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168 | with the following mandatory arguments: |
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169 | |
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170 | "after" specifies after how many seconds (fractional values are |
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171 | supported) the callback should be invoked. "cb" is the callback to |
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172 | invoke in that case. |
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173 | |
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174 | Although the callback might get passed parameters, their value and |
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175 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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176 | callbacks cannot use arguments passed to time watcher callbacks. |
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177 | |
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178 | The timer callback will be invoked at most once: if you want a repeating |
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179 | timer you have to create a new watcher (this is a limitation by both Tk |
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180 | and Glib). |
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181 | |
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182 | Example: |
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183 | |
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184 | # fire an event after 7.7 seconds |
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185 | my $w = AnyEvent->timer (after => 7.7, cb => sub { |
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186 | warn "timeout\n"; |
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187 | }); |
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188 | |
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189 | # to cancel the timer: |
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190 | undef $w; |
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191 | |
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192 | Example 2: |
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193 | |
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194 | # fire an event after 0.5 seconds, then roughly every second |
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195 | my $w; |
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196 | |
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197 | my $cb = sub { |
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198 | # cancel the old timer while creating a new one |
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199 | $w = AnyEvent->timer (after => 1, cb => $cb); |
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200 | }; |
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201 | |
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202 | # start the "loop" by creating the first watcher |
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203 | $w = AnyEvent->timer (after => 0.5, cb => $cb); |
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204 | |
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205 | TIMING ISSUES |
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206 | There are two ways to handle timers: based on real time (relative, "fire |
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207 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
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208 | o'clock"). |
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209 | |
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210 | While most event loops expect timers to specified in a relative way, |
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211 | they use absolute time internally. This makes a difference when your |
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212 | clock "jumps", for example, when ntp decides to set your clock backwards |
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213 | from the wrong date of 2014-01-01 to 2008-01-01, a watcher that is |
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214 | supposed to fire "after" a second might actually take six years to |
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215 | finally fire. |
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216 | |
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217 | AnyEvent cannot compensate for this. The only event loop that is |
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218 | conscious about these issues is EV, which offers both relative |
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219 | (ev_timer, based on true relative time) and absolute (ev_periodic, based |
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220 | on wallclock time) timers. |
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221 | |
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222 | AnyEvent always prefers relative timers, if available, matching the |
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223 | AnyEvent API. |
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224 | |
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225 | SIGNAL WATCHERS |
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226 | You can watch for signals using a signal watcher, "signal" is the signal |
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227 | *name* without any "SIG" prefix, "cb" is the Perl callback to be invoked |
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228 | whenever a signal occurs. |
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229 | |
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230 | Although the callback might get passed parameters, their value and |
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231 | presence is undefined and you cannot rely on them. Portable AnyEvent |
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232 | callbacks cannot use arguments passed to signal watcher callbacks. |
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233 | |
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234 | Multiple signal occurances can be clumped together into one callback |
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235 | invocation, and callback invocation will be synchronous. synchronous |
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236 | means that it might take a while until the signal gets handled by the |
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237 | process, but it is guarenteed not to interrupt any other callbacks. |
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238 | |
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239 | The main advantage of using these watchers is that you can share a |
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240 | signal between multiple watchers. |
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241 | |
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242 | This watcher might use %SIG, so programs overwriting those signals |
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243 | directly will likely not work correctly. |
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244 | |
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245 | Example: exit on SIGINT |
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246 | |
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247 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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248 | |
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249 | CHILD PROCESS WATCHERS |
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250 | You can also watch on a child process exit and catch its exit status. |
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251 | |
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252 | The child process is specified by the "pid" argument (if set to 0, it |
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253 | watches for any child process exit). The watcher will trigger as often |
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254 | as status change for the child are received. This works by installing a |
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255 | signal handler for "SIGCHLD". The callback will be called with the pid |
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256 | and exit status (as returned by waitpid), so unlike other watcher types, |
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257 | you *can* rely on child watcher callback arguments. |
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258 | |
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259 | There is a slight catch to child watchers, however: you usually start |
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260 | them *after* the child process was created, and this means the process |
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261 | could have exited already (and no SIGCHLD will be sent anymore). |
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262 | |
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263 | Not all event models handle this correctly (POE doesn't), but even for |
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264 | event models that *do* handle this correctly, they usually need to be |
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265 | loaded before the process exits (i.e. before you fork in the first |
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266 | place). |
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267 | |
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268 | This means you cannot create a child watcher as the very first thing in |
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269 | an AnyEvent program, you *have* to create at least one watcher before |
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270 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
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271 | |
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272 | Example: fork a process and wait for it |
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273 | |
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274 | my $done = AnyEvent->condvar; |
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275 | |
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276 | AnyEvent::detect; # force event module to be initialised |
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277 | |
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278 | my $pid = fork or exit 5; |
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279 | |
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280 | my $w = AnyEvent->child ( |
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281 | pid => $pid, |
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282 | cb => sub { |
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283 | my ($pid, $status) = @_; |
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284 | warn "pid $pid exited with status $status"; |
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285 | $done->broadcast; |
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286 | }, |
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287 | ); |
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288 | |
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289 | # do something else, then wait for process exit |
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290 | $done->wait; |
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291 | |
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292 | CONDITION VARIABLES |
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293 | Condition variables can be created by calling the "AnyEvent->condvar" |
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294 | method without any arguments. |
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295 | |
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296 | A condition variable waits for a condition - precisely that the |
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297 | "->broadcast" method has been called. |
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298 | |
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299 | They are very useful to signal that a condition has been fulfilled, for |
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300 | example, if you write a module that does asynchronous http requests, |
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301 | then a condition variable would be the ideal candidate to signal the |
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302 | availability of results. |
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303 | |
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304 | You can also use condition variables to block your main program until an |
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305 | event occurs - for example, you could "->wait" in your main program |
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306 | until the user clicks the Quit button in your app, which would |
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307 | "->broadcast" the "quit" event. |
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308 | |
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309 | Note that condition variables recurse into the event loop - if you have |
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310 | two pirces of code that call "->wait" in a round-robbin fashion, you |
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311 | lose. Therefore, condition variables are good to export to your caller, |
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312 | but you should avoid making a blocking wait yourself, at least in |
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313 | callbacks, as this asks for trouble. |
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314 | |
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315 | This object has two methods: |
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316 | |
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317 | $cv->wait |
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318 | Wait (blocking if necessary) until the "->broadcast" method has been |
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319 | called on c<$cv>, while servicing other watchers normally. |
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320 | |
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321 | You can only wait once on a condition - additional calls will return |
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322 | immediately. |
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323 | |
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324 | Not all event models support a blocking wait - some die in that case |
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325 | (programs might want to do that to stay interactive), so *if you are |
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326 | using this from a module, never require a blocking wait*, but let |
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327 | the caller decide whether the call will block or not (for example, |
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328 | by coupling condition variables with some kind of request results |
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329 | and supporting callbacks so the caller knows that getting the result |
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330 | will not block, while still suppporting blocking waits if the caller |
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331 | so desires). |
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332 | |
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333 | Another reason *never* to "->wait" in a module is that you cannot |
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334 | sensibly have two "->wait"'s in parallel, as that would require |
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335 | multiple interpreters or coroutines/threads, none of which |
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336 | "AnyEvent" can supply (the coroutine-aware backends |
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337 | AnyEvent::Impl::CoroEV and AnyEvent::Impl::CoroEvent explicitly |
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338 | support concurrent "->wait"'s from different coroutines, however). |
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339 | |
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340 | $cv->broadcast |
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341 | Flag the condition as ready - a running "->wait" and all further |
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342 | calls to "wait" will (eventually) return after this method has been |
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343 | called. If nobody is waiting the broadcast will be remembered.. |
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344 | |
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345 | Example: |
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346 | |
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347 | # wait till the result is ready |
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348 | my $result_ready = AnyEvent->condvar; |
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349 | |
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350 | # do something such as adding a timer |
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351 | # or socket watcher the calls $result_ready->broadcast |
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352 | # when the "result" is ready. |
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353 | # in this case, we simply use a timer: |
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354 | my $w = AnyEvent->timer ( |
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355 | after => 1, |
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356 | cb => sub { $result_ready->broadcast }, |
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357 | ); |
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358 | |
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359 | # this "blocks" (while handling events) till the watcher |
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360 | # calls broadcast |
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361 | $result_ready->wait; |
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362 | |
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363 | GLOBAL VARIABLES AND FUNCTIONS |
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364 | $AnyEvent::MODEL |
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365 | Contains "undef" until the first watcher is being created. Then it |
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366 | contains the event model that is being used, which is the name of |
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367 | the Perl class implementing the model. This class is usually one of |
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368 | the "AnyEvent::Impl:xxx" modules, but can be any other class in the |
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369 | case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). |
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370 | |
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371 | The known classes so far are: |
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372 | |
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373 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
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374 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
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375 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
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376 | AnyEvent::Impl::Event based on Event, second best choice. |
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377 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
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378 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
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379 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
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380 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
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381 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
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382 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
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383 | |
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384 | There is no support for WxWidgets, as WxWidgets has no support for |
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385 | watching file handles. However, you can use WxWidgets through the |
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386 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
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387 | second, which was considered to be too horrible to even consider for |
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388 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by |
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389 | using it's adaptor. |
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390 | |
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391 | AnyEvent knows about Prima and Wx and will try to use POE when |
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392 | autodetecting them. |
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393 | |
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394 | AnyEvent::detect |
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395 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
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396 | if necessary. You should only call this function right before you |
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397 | would have created an AnyEvent watcher anyway, that is, as late as |
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398 | possible at runtime. |
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399 | |
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400 | WHAT TO DO IN A MODULE |
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401 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
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|
402 | freely, but you should not load a specific event module or rely on it. |
|
|
403 | |
|
|
404 | Be careful when you create watchers in the module body - AnyEvent will |
|
|
405 | decide which event module to use as soon as the first method is called, |
|
|
406 | so by calling AnyEvent in your module body you force the user of your |
|
|
407 | module to load the event module first. |
|
|
408 | |
|
|
409 | Never call "->wait" on a condition variable unless you *know* that the |
|
|
410 | "->broadcast" method has been called on it already. This is because it |
|
|
411 | will stall the whole program, and the whole point of using events is to |
|
|
412 | stay interactive. |
|
|
413 | |
|
|
414 | It is fine, however, to call "->wait" when the user of your module |
|
|
415 | requests it (i.e. if you create a http request object ad have a method |
|
|
416 | called "results" that returns the results, it should call "->wait" |
|
|
417 | freely, as the user of your module knows what she is doing. always). |
|
|
418 | |
|
|
419 | WHAT TO DO IN THE MAIN PROGRAM |
|
|
420 | There will always be a single main program - the only place that should |
|
|
421 | dictate which event model to use. |
|
|
422 | |
|
|
423 | If it doesn't care, it can just "use AnyEvent" and use it itself, or not |
|
|
424 | do anything special (it does not need to be event-based) and let |
|
|
425 | AnyEvent decide which implementation to chose if some module relies on |
|
|
426 | it. |
|
|
427 | |
|
|
428 | If the main program relies on a specific event model. For example, in |
|
|
429 | Gtk2 programs you have to rely on the Glib module. You should load the |
|
|
430 | event module before loading AnyEvent or any module that uses it: |
|
|
431 | generally speaking, you should load it as early as possible. The reason |
|
|
432 | is that modules might create watchers when they are loaded, and AnyEvent |
|
|
433 | will decide on the event model to use as soon as it creates watchers, |
|
|
434 | and it might chose the wrong one unless you load the correct one |
|
|
435 | yourself. |
|
|
436 | |
|
|
437 | You can chose to use a rather inefficient pure-perl implementation by |
|
|
438 | loading the "AnyEvent::Impl::Perl" module, which gives you similar |
|
|
439 | behaviour everywhere, but letting AnyEvent chose is generally better. |
|
|
440 | |
|
|
441 | OTHER MODULES |
|
|
442 | The following is a non-exhaustive list of additional modules that use |
|
|
443 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
444 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
445 | available via CPAN. |
|
|
446 | |
|
|
447 | AnyEvent::Util |
|
|
448 | Contains various utility functions that replace often-used but |
|
|
449 | blocking functions such as "inet_aton" by event-/callback-based |
|
|
450 | versions. |
|
|
451 | |
|
|
452 | AnyEvent::Handle |
|
|
453 | Provide read and write buffers and manages watchers for reads and |
|
|
454 | writes. |
|
|
455 | |
|
|
456 | AnyEvent::Socket |
|
|
457 | Provides a means to do non-blocking connects, accepts etc. |
|
|
458 | |
|
|
459 | AnyEvent::HTTPD |
|
|
460 | Provides a simple web application server framework. |
|
|
461 | |
|
|
462 | AnyEvent::DNS |
|
|
463 | Provides asynchronous DNS resolver capabilities, beyond what |
|
|
464 | AnyEvent::Util offers. |
|
|
465 | |
|
|
466 | AnyEvent::FastPing |
|
|
467 | The fastest ping in the west. |
|
|
468 | |
|
|
469 | Net::IRC3 |
|
|
470 | AnyEvent based IRC client module family. |
|
|
471 | |
|
|
472 | Net::XMPP2 |
|
|
473 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
474 | |
|
|
475 | Net::FCP |
|
|
476 | AnyEvent-based implementation of the Freenet Client Protocol, |
|
|
477 | birthplace of AnyEvent. |
|
|
478 | |
|
|
479 | Event::ExecFlow |
|
|
480 | High level API for event-based execution flow control. |
|
|
481 | |
|
|
482 | Coro |
|
|
483 | Has special support for AnyEvent. |
|
|
484 | |
|
|
485 | IO::Lambda |
|
|
486 | The lambda approach to I/O - don't ask, look there. Can use |
|
|
487 | AnyEvent. |
|
|
488 | |
|
|
489 | IO::AIO |
|
|
490 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
491 | programmer. Can be trivially made to use AnyEvent. |
|
|
492 | |
|
|
493 | BDB Truly asynchronous Berkeley DB access. Can be trivially made to use |
|
|
494 | AnyEvent. |
|
|
495 | |
|
|
496 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
|
|
497 | This is an advanced topic that you do not normally need to use AnyEvent |
|
|
498 | in a module. This section is only of use to event loop authors who want |
|
|
499 | to provide AnyEvent compatibility. |
|
|
500 | |
|
|
501 | If you need to support another event library which isn't directly |
|
|
502 | supported by AnyEvent, you can supply your own interface to it by |
|
|
503 | pushing, before the first watcher gets created, the package name of the |
|
|
504 | event module and the package name of the interface to use onto |
|
|
505 | @AnyEvent::REGISTRY. You can do that before and even without loading |
|
|
506 | AnyEvent, so it is reasonably cheap. |
|
|
507 | |
|
|
508 | Example: |
|
|
509 | |
|
|
510 | push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; |
|
|
511 | |
|
|
512 | This tells AnyEvent to (literally) use the "urxvt::anyevent::" |
|
|
513 | package/class when it finds the "urxvt" package/module is already |
|
|
514 | loaded. |
|
|
515 | |
|
|
516 | When AnyEvent is loaded and asked to find a suitable event model, it |
|
|
517 | will first check for the presence of urxvt by trying to "use" the |
|
|
518 | "urxvt::anyevent" module. |
|
|
519 | |
|
|
520 | The class should provide implementations for all watcher types. See |
|
|
521 | AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and |
|
|
522 | so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see |
|
|
523 | the sources. |
|
|
524 | |
|
|
525 | If you don't provide "signal" and "child" watchers than AnyEvent will |
|
|
526 | provide suitable (hopefully) replacements. |
|
|
527 | |
|
|
528 | The above example isn't fictitious, the *rxvt-unicode* (a.k.a. urxvt) |
|
|
529 | terminal emulator uses the above line as-is. An interface isn't included |
|
|
530 | in AnyEvent because it doesn't make sense outside the embedded |
|
|
531 | interpreter inside *rxvt-unicode*, and it is updated and maintained as |
|
|
532 | part of the *rxvt-unicode* distribution. |
|
|
533 | |
|
|
534 | *rxvt-unicode* also cheats a bit by not providing blocking access to |
|
|
535 | condition variables: code blocking while waiting for a condition will |
|
|
536 | "die". This still works with most modules/usages, and blocking calls |
|
|
537 | must not be done in an interactive application, so it makes sense. |
|
|
538 | |
|
|
539 | ENVIRONMENT VARIABLES |
|
|
540 | The following environment variables are used by this module: |
|
|
541 | |
|
|
542 | "PERL_ANYEVENT_VERBOSE" |
|
|
543 | By default, AnyEvent will be completely silent except in fatal |
|
|
544 | conditions. You can set this environment variable to make AnyEvent |
|
|
545 | more talkative. |
|
|
546 | |
|
|
547 | When set to 1 or higher, causes AnyEvent to warn about unexpected |
|
|
548 | conditions, such as not being able to load the event model specified |
|
|
549 | by "PERL_ANYEVENT_MODEL". |
|
|
550 | |
|
|
551 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
|
|
552 | event model it chooses. |
|
|
553 | |
|
|
554 | "PERL_ANYEVENT_MODEL" |
|
|
555 | This can be used to specify the event model to be used by AnyEvent, |
|
|
556 | before autodetection and -probing kicks in. It must be a string |
|
|
557 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
|
|
558 | gets prepended and the resulting module name is loaded and if the |
|
|
559 | load was successful, used as event model. If it fails to load |
|
|
560 | AnyEvent will proceed with autodetection and -probing. |
|
|
561 | |
|
|
562 | This functionality might change in future versions. |
|
|
563 | |
|
|
564 | For example, to force the pure perl model (AnyEvent::Impl::Perl) you |
|
|
565 | could start your program like this: |
|
|
566 | |
|
|
567 | PERL_ANYEVENT_MODEL=Perl perl ... |
|
|
568 | |
|
|
569 | EXAMPLE PROGRAM |
|
|
570 | The following program uses an I/O watcher to read data from STDIN, a |
|
|
571 | timer to display a message once per second, and a condition variable to |
|
|
572 | quit the program when the user enters quit: |
|
|
573 | |
|
|
574 | use AnyEvent; |
|
|
575 | |
|
|
576 | my $cv = AnyEvent->condvar; |
|
|
577 | |
|
|
578 | my $io_watcher = AnyEvent->io ( |
|
|
579 | fh => \*STDIN, |
|
|
580 | poll => 'r', |
|
|
581 | cb => sub { |
|
|
582 | warn "io event <$_[0]>\n"; # will always output <r> |
|
|
583 | chomp (my $input = <STDIN>); # read a line |
|
|
584 | warn "read: $input\n"; # output what has been read |
|
|
585 | $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i |
|
|
586 | }, |
|
|
587 | ); |
|
|
588 | |
|
|
589 | my $time_watcher; # can only be used once |
|
|
590 | |
|
|
591 | sub new_timer { |
|
|
592 | $timer = AnyEvent->timer (after => 1, cb => sub { |
|
|
593 | warn "timeout\n"; # print 'timeout' about every second |
|
|
594 | &new_timer; # and restart the time |
|
|
595 | }); |
|
|
596 | } |
|
|
597 | |
|
|
598 | new_timer; # create first timer |
|
|
599 | |
|
|
600 | $cv->wait; # wait until user enters /^q/i |
|
|
601 | |
|
|
602 | REAL-WORLD EXAMPLE |
|
|
603 | Consider the Net::FCP module. It features (among others) the following |
|
|
604 | API calls, which are to freenet what HTTP GET requests are to http: |
|
|
605 | |
|
|
606 | my $data = $fcp->client_get ($url); # blocks |
|
|
607 | |
|
|
608 | my $transaction = $fcp->txn_client_get ($url); # does not block |
|
|
609 | $transaction->cb ( sub { ... } ); # set optional result callback |
|
|
610 | my $data = $transaction->result; # possibly blocks |
|
|
611 | |
|
|
612 | The "client_get" method works like "LWP::Simple::get": it requests the |
|
|
613 | given URL and waits till the data has arrived. It is defined to be: |
|
|
614 | |
|
|
615 | sub client_get { $_[0]->txn_client_get ($_[1])->result } |
|
|
616 | |
|
|
617 | And in fact is automatically generated. This is the blocking API of |
|
|
618 | Net::FCP, and it works as simple as in any other, similar, module. |
|
|
619 | |
|
|
620 | More complicated is "txn_client_get": It only creates a transaction |
|
|
621 | (completion, result, ...) object and initiates the transaction. |
|
|
622 | |
|
|
623 | my $txn = bless { }, Net::FCP::Txn::; |
|
|
624 | |
|
|
625 | It also creates a condition variable that is used to signal the |
|
|
626 | completion of the request: |
|
|
627 | |
|
|
628 | $txn->{finished} = AnyAvent->condvar; |
|
|
629 | |
|
|
630 | It then creates a socket in non-blocking mode. |
|
|
631 | |
|
|
632 | socket $txn->{fh}, ...; |
|
|
633 | fcntl $txn->{fh}, F_SETFL, O_NONBLOCK; |
|
|
634 | connect $txn->{fh}, ... |
|
|
635 | and !$!{EWOULDBLOCK} |
|
|
636 | and !$!{EINPROGRESS} |
|
|
637 | and Carp::croak "unable to connect: $!\n"; |
|
|
638 | |
|
|
639 | Then it creates a write-watcher which gets called whenever an error |
|
|
640 | occurs or the connection succeeds: |
|
|
641 | |
|
|
642 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w }); |
|
|
643 | |
|
|
644 | And returns this transaction object. The "fh_ready_w" callback gets |
|
|
645 | called as soon as the event loop detects that the socket is ready for |
|
|
646 | writing. |
|
|
647 | |
|
|
648 | The "fh_ready_w" method makes the socket blocking again, writes the |
|
|
649 | request data and replaces the watcher by a read watcher (waiting for |
|
|
650 | reply data). The actual code is more complicated, but that doesn't |
|
|
651 | matter for this example: |
|
|
652 | |
|
|
653 | fcntl $txn->{fh}, F_SETFL, 0; |
|
|
654 | syswrite $txn->{fh}, $txn->{request} |
|
|
655 | or die "connection or write error"; |
|
|
656 | $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); |
|
|
657 | |
|
|
658 | Again, "fh_ready_r" waits till all data has arrived, and then stores the |
|
|
659 | result and signals any possible waiters that the request ahs finished: |
|
|
660 | |
|
|
661 | sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; |
|
|
662 | |
|
|
663 | if (end-of-file or data complete) { |
|
|
664 | $txn->{result} = $txn->{buf}; |
|
|
665 | $txn->{finished}->broadcast; |
|
|
666 | $txb->{cb}->($txn) of $txn->{cb}; # also call callback |
|
|
667 | } |
|
|
668 | |
|
|
669 | The "result" method, finally, just waits for the finished signal (if the |
|
|
670 | request was already finished, it doesn't wait, of course, and returns |
|
|
671 | the data: |
|
|
672 | |
|
|
673 | $txn->{finished}->wait; |
|
|
674 | return $txn->{result}; |
|
|
675 | |
|
|
676 | The actual code goes further and collects all errors ("die"s, |
|
|
677 | exceptions) that occured during request processing. The "result" method |
|
|
678 | detects whether an exception as thrown (it is stored inside the $txn |
|
|
679 | object) and just throws the exception, which means connection errors and |
|
|
680 | other problems get reported tot he code that tries to use the result, |
|
|
681 | not in a random callback. |
|
|
682 | |
|
|
683 | All of this enables the following usage styles: |
|
|
684 | |
|
|
685 | 1. Blocking: |
|
|
686 | |
|
|
687 | my $data = $fcp->client_get ($url); |
|
|
688 | |
|
|
689 | 2. Blocking, but running in parallel: |
|
|
690 | |
|
|
691 | my @datas = map $_->result, |
|
|
692 | map $fcp->txn_client_get ($_), |
|
|
693 | @urls; |
|
|
694 | |
|
|
695 | Both blocking examples work without the module user having to know |
|
|
696 | anything about events. |
|
|
697 | |
|
|
698 | 3a. Event-based in a main program, using any supported event module: |
|
|
699 | |
|
|
700 | use EV; |
|
|
701 | |
|
|
702 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
703 | my $txn = shift; |
|
|
704 | my $data = $txn->result; |
|
|
705 | ... |
|
|
706 | }); |
|
|
707 | |
|
|
708 | EV::loop; |
|
|
709 | |
|
|
710 | 3b. The module user could use AnyEvent, too: |
|
|
711 | |
|
|
712 | use AnyEvent; |
|
|
713 | |
|
|
714 | my $quit = AnyEvent->condvar; |
|
|
715 | |
|
|
716 | $fcp->txn_client_get ($url)->cb (sub { |
|
|
717 | ... |
|
|
718 | $quit->broadcast; |
|
|
719 | }); |
|
|
720 | |
|
|
721 | $quit->wait; |
|
|
722 | |
|
|
723 | BENCHMARKS |
|
|
724 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
725 | over the event loops themselves and to give you an impression of the |
|
|
726 | speed of various event loops I prepared some benchmarks. |
|
|
727 | |
|
|
728 | BENCHMARKING ANYEVENT OVERHEAD |
|
|
729 | Here is a benchmark of various supported event models used natively and |
|
|
730 | through anyevent. The benchmark creates a lot of timers (with a zero |
|
|
731 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
|
|
732 | which it is), lets them fire exactly once and destroys them again. |
|
|
733 | |
|
|
734 | Source code for this benchmark is found as eg/bench in the AnyEvent |
|
|
735 | distribution. |
|
|
736 | |
|
|
737 | Explanation of the columns |
|
|
738 | *watcher* is the number of event watchers created/destroyed. Since |
|
|
739 | different event models feature vastly different performances, each event |
|
|
740 | loop was given a number of watchers so that overall runtime is |
|
|
741 | acceptable and similar between tested event loop (and keep them from |
|
|
742 | crashing): Glib would probably take thousands of years if asked to |
|
|
743 | process the same number of watchers as EV in this benchmark. |
|
|
744 | |
|
|
745 | *bytes* is the number of bytes (as measured by the resident set size, |
|
|
746 | RSS) consumed by each watcher. This method of measuring captures both C |
|
|
747 | and Perl-based overheads. |
|
|
748 | |
|
|
749 | *create* is the time, in microseconds (millionths of seconds), that it |
|
|
750 | takes to create a single watcher. The callback is a closure shared |
|
|
751 | between all watchers, to avoid adding memory overhead. That means |
|
|
752 | closure creation and memory usage is not included in the figures. |
|
|
753 | |
|
|
754 | *invoke* is the time, in microseconds, used to invoke a simple callback. |
|
|
755 | The callback simply counts down a Perl variable and after it was invoked |
|
|
756 | "watcher" times, it would "->broadcast" a condvar once to signal the end |
|
|
757 | of this phase. |
|
|
758 | |
|
|
759 | *destroy* is the time, in microseconds, that it takes to destroy a |
|
|
760 | single watcher. |
|
|
761 | |
|
|
762 | Results |
|
|
763 | name watchers bytes create invoke destroy comment |
|
|
764 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
|
|
765 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
|
|
766 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
|
|
767 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
|
|
768 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
|
|
769 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
|
|
770 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
|
|
771 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
|
|
772 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
|
|
773 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
|
|
774 | |
|
|
775 | Discussion |
|
|
776 | The benchmark does *not* measure scalability of the event loop very |
|
|
777 | well. For example, a select-based event loop (such as the pure perl one) |
|
|
778 | can never compete with an event loop that uses epoll when the number of |
|
|
779 | file descriptors grows high. In this benchmark, all events become ready |
|
|
780 | at the same time, so select/poll-based implementations get an unnatural |
|
|
781 | speed boost. |
|
|
782 | |
|
|
783 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
784 | overall speed, that is, creating twice as many watchers doesn't take |
|
|
785 | twice the time - usually it takes longer. This puts event loops tested |
|
|
786 | with a higher number of watchers at a disadvantage. |
|
|
787 | |
|
|
788 | To put the range of results into perspective, consider that on the |
|
|
789 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
790 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
|
|
791 | CPU cycles with POE. |
|
|
792 | |
|
|
793 | "EV" is the sole leader regarding speed and memory use, which are both |
|
|
794 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
|
|
795 | far less memory than any other event loop and is still faster than Event |
|
|
796 | natively. |
|
|
797 | |
|
|
798 | The pure perl implementation is hit in a few sweet spots (both the |
|
|
799 | constant timeout and the use of a single fd hit optimisations in the |
|
|
800 | perl interpreter and the backend itself). Nevertheless this shows that |
|
|
801 | it adds very little overhead in itself. Like any select-based backend |
|
|
802 | its performance becomes really bad with lots of file descriptors (and |
|
|
803 | few of them active), of course, but this was not subject of this |
|
|
804 | benchmark. |
|
|
805 | |
|
|
806 | The "Event" module has a relatively high setup and callback invocation |
|
|
807 | cost, but overall scores in on the third place. |
|
|
808 | |
|
|
809 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
|
|
810 | callback invocation and overall ends up in the same class as "Event". |
|
|
811 | However, Glib scales extremely badly, doubling the number of watchers |
|
|
812 | increases the processing time by more than a factor of four, making it |
|
|
813 | completely unusable when using larger numbers of watchers (note that |
|
|
814 | only a single file descriptor was used in the benchmark, so |
|
|
815 | inefficiencies of "poll" do not account for this). |
|
|
816 | |
|
|
817 | The "Tk" adaptor works relatively well. The fact that it crashes with |
|
|
818 | more than 2000 watchers is a big setback, however, as correctness takes |
|
|
819 | precedence over speed. Nevertheless, its performance is surprising, as |
|
|
820 | the file descriptor is dup()ed for each watcher. This shows that the |
|
|
821 | dup() employed by some adaptors is not a big performance issue (it does |
|
|
822 | incur a hidden memory cost inside the kernel which is not reflected in |
|
|
823 | the figures above). |
|
|
824 | |
|
|
825 | "POE", regardless of underlying event loop (whether using its pure perl |
|
|
826 | select-based backend or the Event module, the POE-EV backend couldn't be |
|
|
827 | tested because it wasn't working) shows abysmal performance and memory |
|
|
828 | usage: Watchers use almost 30 times as much memory as EV watchers, and |
|
|
829 | 10 times as much memory as Event (the high memory requirements are |
|
|
830 | caused by requiring a session for each watcher). Watcher invocation |
|
|
831 | speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
832 | implementation. The design of the POE adaptor class in AnyEvent can not |
|
|
833 | really account for this, as session creation overhead is small compared |
|
|
834 | to execution of the state machine, which is coded pretty optimally |
|
|
835 | within AnyEvent::Impl::POE. POE simply seems to be abysmally slow. |
|
|
836 | |
|
|
837 | Summary |
|
|
838 | * Using EV through AnyEvent is faster than any other event loop (even |
|
|
839 | when used without AnyEvent), but most event loops have acceptable |
|
|
840 | performance with or without AnyEvent. |
|
|
841 | |
|
|
842 | * The overhead AnyEvent adds is usually much smaller than the overhead |
|
|
843 | of the actual event loop, only with extremely fast event loops such |
|
|
844 | as EV adds AnyEvent significant overhead. |
|
|
845 | |
|
|
846 | * You should avoid POE like the plague if you want performance or |
|
|
847 | reasonable memory usage. |
|
|
848 | |
|
|
849 | BENCHMARKING THE LARGE SERVER CASE |
|
|
850 | This benchmark atcually benchmarks the event loop itself. It works by |
|
|
851 | creating a number of "servers": each server consists of a socketpair, a |
|
|
852 | timeout watcher that gets reset on activity (but never fires), and an |
|
|
853 | I/O watcher waiting for input on one side of the socket. Each time the |
|
|
854 | socket watcher reads a byte it will write that byte to a random other |
|
|
855 | "server". |
|
|
856 | |
|
|
857 | The effect is that there will be a lot of I/O watchers, only part of |
|
|
858 | which are active at any one point (so there is a constant number of |
|
|
859 | active fds for each loop iterstaion, but which fds these are is random). |
|
|
860 | The timeout is reset each time something is read because that reflects |
|
|
861 | how most timeouts work (and puts extra pressure on the event loops). |
|
|
862 | |
|
|
863 | In this benchmark, we use 10000 socketpairs (20000 sockets), of which |
|
|
864 | 100 (1%) are active. This mirrors the activity of large servers with |
|
|
865 | many connections, most of which are idle at any one point in time. |
|
|
866 | |
|
|
867 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
|
|
868 | distribution. |
|
|
869 | |
|
|
870 | Explanation of the columns |
|
|
871 | *sockets* is the number of sockets, and twice the number of "servers" |
|
|
872 | (as each server has a read and write socket end). |
|
|
873 | |
|
|
874 | *create* is the time it takes to create a socketpair (which is |
|
|
875 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
|
|
876 | |
|
|
877 | *request*, the most important value, is the time it takes to handle a |
|
|
878 | single "request", that is, reading the token from the pipe and |
|
|
879 | forwarding it to another server. This includes deleting the old timeout |
|
|
880 | and creating a new one that moves the timeout into the future. |
|
|
881 | |
|
|
882 | Results |
|
|
883 | name sockets create request |
|
|
884 | EV 20000 69.01 11.16 |
|
|
885 | Perl 20000 73.32 35.87 |
|
|
886 | Event 20000 212.62 257.32 |
|
|
887 | Glib 20000 651.16 1896.30 |
|
|
888 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
|
|
889 | |
|
|
890 | Discussion |
|
|
891 | This benchmark *does* measure scalability and overall performance of the |
|
|
892 | particular event loop. |
|
|
893 | |
|
|
894 | EV is again fastest. Since it is using epoll on my system, the setup |
|
|
895 | time is relatively high, though. |
|
|
896 | |
|
|
897 | Perl surprisingly comes second. It is much faster than the C-based event |
|
|
898 | loops Event and Glib. |
|
|
899 | |
|
|
900 | Event suffers from high setup time as well (look at its code and you |
|
|
901 | will understand why). Callback invocation also has a high overhead |
|
|
902 | compared to the "$_->() for .."-style loop that the Perl event loop |
|
|
903 | uses. Event uses select or poll in basically all documented |
|
|
904 | configurations. |
|
|
905 | |
|
|
906 | Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It |
|
|
907 | clearly fails to perform with many filehandles or in busy servers. |
|
|
908 | |
|
|
909 | POE is still completely out of the picture, taking over 1000 times as |
|
|
910 | long as EV, and over 100 times as long as the Perl implementation, even |
|
|
911 | though it uses a C-based event loop in this case. |
|
|
912 | |
|
|
913 | Summary |
|
|
914 | * The pure perl implementation performs extremely well, considering |
|
|
915 | that it uses select. |
|
|
916 | |
|
|
917 | * Avoid Glib or POE in large projects where performance matters. |
|
|
918 | |
|
|
919 | BENCHMARKING SMALL SERVERS |
|
|
920 | While event loops should scale (and select-based ones do not...) even to |
|
|
921 | large servers, most programs we (or I :) actually write have only a few |
|
|
922 | I/O watchers. |
|
|
923 | |
|
|
924 | In this benchmark, I use the same benchmark program as in the large |
|
|
925 | server case, but it uses only eight "servers", of which three are active |
|
|
926 | at any one time. This should reflect performance for a small server |
|
|
927 | relatively well. |
|
|
928 | |
|
|
929 | The columns are identical to the previous table. |
|
|
930 | |
|
|
931 | Results |
|
|
932 | name sockets create request |
|
|
933 | EV 16 20.00 6.54 |
|
|
934 | Perl 16 25.75 12.62 |
|
|
935 | Event 16 81.27 35.86 |
|
|
936 | Glib 16 32.63 15.48 |
|
|
937 | POE 16 261.87 276.28 uses POE::Loop::Event |
|
|
938 | |
|
|
939 | Discussion |
|
|
940 | The benchmark tries to test the performance of a typical small server. |
|
|
941 | While knowing how various event loops perform is interesting, keep in |
|
|
942 | mind that their overhead in this case is usually not as important, due |
|
|
943 | to the small absolute number of watchers (that is, you need efficiency |
|
|
944 | and speed most when you have lots of watchers, not when you only have a |
|
|
945 | few of them). |
|
|
946 | |
|
|
947 | EV is again fastest. |
|
|
948 | |
|
|
949 | Perl again comes second. It is noticably faster than the C-based event |
|
|
950 | loops Event and Glib, although the difference is too small to really |
|
|
951 | matter. |
|
|
952 | |
|
|
953 | POE also performs much better in this case, but is is still far behind |
|
|
954 | the others. |
|
|
955 | |
|
|
956 | Summary |
|
|
957 | * C-based event loops perform very well with small number of watchers, |
|
|
958 | as the management overhead dominates. |
|
|
959 | |
|
|
960 | FORK |
|
|
961 | Most event libraries are not fork-safe. The ones who are usually are |
|
|
962 | because they are so inefficient. Only EV is fully fork-aware. |
|
|
963 | |
|
|
964 | If you have to fork, you must either do so *before* creating your first |
|
|
965 | watcher OR you must not use AnyEvent at all in the child. |
|
|
966 | |
|
|
967 | SECURITY CONSIDERATIONS |
|
|
968 | AnyEvent can be forced to load any event model via |
|
|
969 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
|
|
970 | to execute arbitrary code or directly gain access, it can easily be used |
|
|
971 | to make the program hang or malfunction in subtle ways, as AnyEvent |
|
|
972 | watchers will not be active when the program uses a different event |
|
|
973 | model than specified in the variable. |
|
|
974 | |
|
|
975 | You can make AnyEvent completely ignore this variable by deleting it |
|
|
976 | before the first watcher gets created, e.g. with a "BEGIN" block: |
|
|
977 | |
|
|
978 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
|
|
979 | |
|
|
980 | use AnyEvent; |
|
|
981 | |
|
|
982 | SEE ALSO |
|
|
983 | Event modules: Coro::EV, EV, EV::Glib, Glib::EV, Coro::Event, Event, |
|
|
984 | Glib::Event, Glib, Coro, Tk, Event::Lib, Qt, POE. |
|
|
985 | |
|
|
986 | Implementations: AnyEvent::Impl::CoroEV, AnyEvent::Impl::EV, |
|
|
987 | AnyEvent::Impl::CoroEvent, AnyEvent::Impl::Event, AnyEvent::Impl::Glib, |
|
|
988 | AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, AnyEvent::Impl::EventLib, |
|
|
989 | AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
|
|
990 | |
|
|
991 | Nontrivial usage examples: Net::FCP, Net::XMPP2. |
|
|
992 | |
|
|
993 | AUTHOR |
|
|
994 | Marc Lehmann <schmorp@schmorp.de> |
|
|
995 | http://home.schmorp.de/ |
|
|
996 | |