1 | NAME |
1 | NAME |
2 | EV - perl interface to libevent, monkey.org/~provos/libevent/ |
2 | EV - perl interface to libev, a high performance full-featured event |
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3 | loop |
3 | |
4 | |
4 | SYNOPSIS |
5 | SYNOPSIS |
5 | use EV; |
6 | use EV; |
6 | |
7 | |
7 | # TIMER |
8 | # TIMERS |
8 | |
9 | |
9 | my $w = EV::timer 2, 0, sub { |
10 | my $w = EV::timer 2, 0, sub { |
10 | warn "is called after 2s"; |
11 | warn "is called after 2s"; |
11 | }; |
12 | }; |
12 | |
13 | |
13 | my $w = EV::timer 2, 1, sub { |
14 | my $w = EV::timer 2, 2, sub { |
14 | warn "is called roughly every 2s (repeat = 1)"; |
15 | warn "is called roughly every 2s (repeat = 2)"; |
15 | }; |
16 | }; |
16 | |
17 | |
17 | undef $w; # destroy event watcher again |
18 | undef $w; # destroy event watcher again |
18 | |
19 | |
19 | # IO |
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20 | |
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21 | my $w = EV::timer_abs 0, 60, sub { |
20 | my $w = EV::periodic 0, 60, 0, sub { |
22 | warn "is called every minute, on the minute, exactly"; |
21 | warn "is called every minute, on the minute, exactly"; |
23 | }; |
22 | }; |
24 | |
23 | |
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24 | # IO |
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25 | |
25 | my $w = EV::io \*STDIN, EV::READ | EV::PERSIST, sub { |
26 | my $w = EV::io *STDIN, EV::READ, sub { |
26 | my ($w, $events) = @_; # all callbacks get the watcher object and event mask |
27 | my ($w, $revents) = @_; # all callbacks receive the watcher and event mask |
27 | if ($events & EV::TIMEOUT) { |
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28 | warn "nothign received on stdin for 10 seconds, retrying"; |
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29 | } else { |
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30 | warn "stdin is readable, you entered: ", <STDIN>; |
28 | warn "stdin is readable, you entered: ", <STDIN>; |
31 | } |
29 | }; |
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30 | |
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31 | # SIGNALS |
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32 | |
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33 | my $w = EV::signal 'QUIT', sub { |
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34 | warn "sigquit received\n"; |
32 | }; |
35 | }; |
33 | $w->timeout (10); |
36 | |
34 | |
37 | # CHILD/PID STATUS CHANGES |
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38 | |
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39 | my $w = EV::child 666, 0, sub { |
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40 | my ($w, $revents) = @_; |
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41 | my $status = $w->rstatus; |
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42 | }; |
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43 | |
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44 | # STAT CHANGES |
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45 | my $w = EV::stat "/etc/passwd", 10, sub { |
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46 | my ($w, $revents) = @_; |
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47 | warn $w->path, " has changed somehow.\n"; |
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48 | }; |
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49 | |
35 | # MAINLOOP |
50 | # MAINLOOP |
36 | EV::dispatch; # loop as long as watchers are active |
51 | EV::loop; # loop until EV::unloop is called or all watchers stop |
37 | EV::loop; # the same thing |
52 | EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
38 | EV::loop EV::LOOP_ONCE; |
53 | EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
39 | EV::loop EV::LOOP_ONSHOT; |
54 | |
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55 | BEFORE YOU START USING THIS MODULE |
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56 | If you only need timer, I/O, signal, child and idle watchers and not the |
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57 | advanced functionality of this module, consider using AnyEvent instead, |
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58 | specifically the simplified API described in AE. |
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59 | |
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60 | When used with EV as backend, the AE API is as fast as the native EV |
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61 | API, but your programs/modules will still run with many other event |
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62 | loops. |
40 | |
63 | |
41 | DESCRIPTION |
64 | DESCRIPTION |
42 | This module provides an interface to libevent |
65 | This module provides an interface to libev |
43 | (<http://monkey.org/~provos/libevent/>). You probably should acquaint |
66 | (<http://software.schmorp.de/pkg/libev.html>). While the documentation |
44 | yourself with its documentation and source code to be able to use this |
67 | below is comprehensive, one might also consult the documentation of |
45 | module fully. |
68 | libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or |
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69 | perldoc EV::libev) for more subtle details on watcher semantics or some |
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70 | discussion on the available backends, or how to force a specific backend |
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71 | with "LIBEV_FLAGS", or just about in any case because it has much more |
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72 | detailed information. |
46 | |
73 | |
47 | Please note thta this module disables the libevent EPOLL method by |
74 | This module is very fast and scalable. It is actually so fast that you |
48 | default, see BUGS, below, if you need to enable it. |
75 | can use it through the AnyEvent module, stay portable to other event |
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76 | loops (if you don't rely on any watcher types not available through it) |
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77 | and still be faster than with any other event loop currently supported |
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78 | in Perl. |
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79 | |
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80 | PORTING FROM EV 3.X to 4.X |
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81 | EV version 4 introduces a number of incompatible changes summarised |
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82 | here. According to the depreciation strategy used by libev, there is a |
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83 | compatibility layer in place so programs should continue to run |
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84 | unchanged (the XS interface lacks this layer, so programs using that one |
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85 | need to be updated). |
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86 | |
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87 | This compatibility layer will be switched off in some future release. |
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88 | |
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89 | All changes relevant to Perl are renames of symbols, functions and |
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90 | methods: |
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91 | |
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92 | EV::loop => EV::run |
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93 | EV::LOOP_NONBLOCK => EV::RUN_NOWAIT |
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94 | EV::LOOP_ONESHOT => EV::RUN_ONCE |
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95 | |
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96 | EV::unloop => EV::break |
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97 | EV::UNLOOP_CANCEL => EV::BREAK_CANCEL |
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98 | EV::UNLOOP_ONE => EV::BREAK_ONE |
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99 | EV::UNLOOP_ALL => EV::BREAK_ALL |
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100 | |
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101 | EV::TIMEOUT => EV::TIMER |
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102 | |
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103 | EV::loop_count => EV::iteration |
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104 | EV::loop_depth => EV::depth |
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105 | EV::loop_verify => EV::verify |
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106 | |
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107 | The loop object methods corresponding to the functions above have been |
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108 | similarly renamed. |
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109 | |
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110 | MODULE EXPORTS |
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111 | This module does not export any symbols. |
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112 | |
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113 | EVENT LOOPS |
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114 | EV supports multiple event loops: There is a single "default event loop" |
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115 | that can handle everything including signals and child watchers, and any |
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116 | number of "dynamic event loops" that can use different backends (with |
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117 | various limitations), but no child and signal watchers. |
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118 | |
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119 | You do not have to do anything to create the default event loop: When |
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120 | the module is loaded a suitable backend is selected on the premise of |
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121 | selecting a working backend (which for example rules out kqueue on most |
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122 | BSDs). Modules should, unless they have "special needs" always use the |
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123 | default loop as this is fastest (perl-wise), best supported by other |
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124 | modules (e.g. AnyEvent or Coro) and most portable event loop. |
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125 | |
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126 | For specific programs you can create additional event loops dynamically. |
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127 | |
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128 | If you want to take advantage of kqueue (which often works properly for |
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129 | sockets only) even though the default loop doesn't enable it, you can |
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130 | *embed* a kqueue loop into the default loop: running the default loop |
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131 | will then also service the kqueue loop to some extent. See the example |
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132 | in the section about embed watchers for an example on how to achieve |
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133 | that. |
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134 | |
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135 | $loop = new EV::Loop [$flags] |
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136 | Create a new event loop as per the specified flags. Please refer to |
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137 | the "ev_loop_new ()" function description in the libev documentation |
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138 | (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI |
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139 | ONS>, or locally-installed as EV::libev manpage) for more info. |
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140 | |
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141 | The loop will automatically be destroyed when it is no longer |
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142 | referenced by any watcher and the loop object goes out of scope. |
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143 | |
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144 | If you are not embedding the loop, then Using "EV::FLAG_FORKCHECK" |
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145 | is recommended, as only the default event loop is protected by this |
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146 | module. If you *are* embedding this loop in the default loop, this |
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147 | is not necessary, as "EV::embed" automatically does the right thing |
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148 | on fork. |
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149 | |
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150 | $loop->loop_fork |
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151 | Must be called after a fork in the child, before entering or |
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152 | continuing the event loop. An alternative is to use |
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153 | "EV::FLAG_FORKCHECK" which calls this function automatically, at |
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154 | some performance loss (refer to the libev documentation). |
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155 | |
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156 | $loop->loop_verify |
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157 | Calls "ev_verify" to make internal consistency checks (for debugging |
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158 | libev) and abort the program if any data structures were found to be |
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159 | corrupted. |
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160 | |
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161 | $loop = EV::default_loop [$flags] |
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162 | Return the default loop (which is a singleton object). Since this |
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163 | module already creates the default loop with default flags, |
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164 | specifying flags here will not have any effect unless you destroy |
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165 | the default loop first, which isn't supported. So in short: don't do |
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166 | it, and if you break it, you get to keep the pieces. |
49 | |
167 | |
50 | BASIC INTERFACE |
168 | BASIC INTERFACE |
51 | $EV::NPRI |
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52 | How many priority levels are available. |
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53 | |
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54 | $EV::DIED |
169 | $EV::DIED |
55 | Must contain a reference to a function that is called when a |
170 | Must contain a reference to a function that is called when a |
56 | callback throws an exception (with $@ containing thr error). The |
171 | callback throws an exception (with $@ containing the error). The |
57 | default prints an informative message and continues. |
172 | default prints an informative message and continues. |
58 | |
173 | |
59 | If this callback throws an exception it will be silently ignored. |
174 | If this callback throws an exception it will be silently ignored. |
60 | |
175 | |
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176 | $flags = EV::supported_backends |
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177 | $flags = EV::recommended_backends |
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178 | $flags = EV::embeddable_backends |
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179 | Returns the set (see "EV::BACKEND_*" flags) of backends supported by |
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180 | this instance of EV, the set of recommended backends (supposed to be |
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181 | good) for this platform and the set of embeddable backends (see |
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182 | EMBED WATCHERS). |
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183 | |
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184 | EV::sleep $seconds |
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185 | Block the process for the given number of (fractional) seconds. |
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186 | |
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187 | $time = EV::time |
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188 | Returns the current time in (fractional) seconds since the epoch. |
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189 | |
61 | $time = EV::now |
190 | $time = EV::now |
62 | Returns the time in (fractional) seconds since the epoch. |
191 | $time = $loop->now |
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192 | Returns the time the last event loop iteration has been started. |
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193 | This is the time that (relative) timers are based on, and referring |
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194 | to it is usually faster then calling EV::time. |
63 | |
195 | |
64 | $version = EV::version |
196 | EV::now_update |
65 | $method = EV::method |
197 | $loop->now_update |
66 | Return version string and event polling method used. |
198 | Establishes the current time by querying the kernel, updating the |
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199 | time returned by "EV::now" in the progress. This is a costly |
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200 | operation and is usually done automatically within "EV::loop". |
67 | |
201 | |
68 | EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT |
202 | This function is rarely useful, but when some event callback runs |
69 | EV::loopexit $after |
203 | for a very long time without entering the event loop, updating |
70 | Exit any active loop or dispatch after $after seconds or immediately |
204 | libev's idea of the current time is a good idea. |
71 | if $after is missing or zero. |
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72 | |
205 | |
73 | EV::dispatch |
206 | EV::suspend |
74 | Same as "EV::loop 0". |
207 | $loop->suspend |
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208 | EV::resume |
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209 | $loop->resume |
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210 | These two functions suspend and resume a loop, for use when the loop |
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211 | is not used for a while and timeouts should not be processed. |
75 | |
212 | |
76 | EV::event $callback |
213 | A typical use case would be an interactive program such as a game: |
77 | Creates a new event watcher waiting for nothing, calling the given |
214 | When the user presses "^Z" to suspend the game and resumes it an |
78 | callback. |
215 | hour later it would be best to handle timeouts as if no time had |
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216 | actually passed while the program was suspended. This can be |
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217 | achieved by calling "suspend" in your "SIGTSTP" handler, sending |
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218 | yourself a "SIGSTOP" and calling "resume" directly afterwards to |
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219 | resume timer processing. |
79 | |
220 | |
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221 | Effectively, all "timer" watchers will be delayed by the time spend |
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222 | between "suspend" and "resume", and all "periodic" watchers will be |
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223 | rescheduled (that is, they will lose any events that would have |
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224 | occured while suspended). |
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225 | |
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226 | After calling "suspend" you must not call *any* function on the |
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227 | given loop other than "resume", and you must not call "resume" |
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228 | without a previous call to "suspend". |
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229 | |
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230 | Calling "suspend"/"resume" has the side effect of updating the event |
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231 | loop time (see "now_update"). |
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232 | |
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233 | $backend = EV::backend |
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234 | $backend = $loop->backend |
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235 | Returns an integer describing the backend used by libev |
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236 | (EV::BACKEND_SELECT or EV::BACKEND_EPOLL). |
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237 | |
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238 | EV::loop [$flags] |
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239 | $loop->loop ([$flags]) |
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240 | Begin checking for events and calling callbacks. It returns when a |
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241 | callback calls EV::unloop. |
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242 | |
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243 | The $flags argument can be one of the following: |
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244 | |
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245 | 0 as above |
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246 | EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
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247 | EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
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248 | |
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249 | EV::unloop [$how] |
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250 | $loop->unloop ([$how]) |
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251 | When called with no arguments or an argument of EV::UNLOOP_ONE, |
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252 | makes the innermost call to EV::loop return. |
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253 | |
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254 | When called with an argument of EV::UNLOOP_ALL, all calls to |
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255 | EV::loop will return as fast as possible. |
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256 | |
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257 | $count = EV::loop_count |
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258 | $count = $loop->loop_count |
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259 | Return the number of times the event loop has polled for new events. |
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260 | Sometimes useful as a generation counter. |
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261 | |
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262 | EV::once $fh_or_undef, $events, $timeout, $cb->($revents) |
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263 | $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) |
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264 | This function rolls together an I/O and a timer watcher for a single |
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265 | one-shot event without the need for managing a watcher object. |
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266 | |
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267 | If $fh_or_undef is a filehandle or file descriptor, then $events |
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268 | must be a bitset containing either "EV::READ", "EV::WRITE" or |
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269 | "EV::READ | EV::WRITE", indicating the type of I/O event you want to |
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270 | wait for. If you do not want to wait for some I/O event, specify |
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271 | "undef" for $fh_or_undef and 0 for $events). |
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272 | |
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273 | If timeout is "undef" or negative, then there will be no timeout. |
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274 | Otherwise a EV::timer with this value will be started. |
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275 | |
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276 | When an error occurs or either the timeout or I/O watcher triggers, |
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277 | then the callback will be called with the received event set (in |
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278 | general you can expect it to be a combination of "EV::ERROR", |
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279 | "EV::READ", "EV::WRITE" and "EV::TIMER"). |
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280 | |
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281 | EV::once doesn't return anything: the watchers stay active till |
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282 | either of them triggers, then they will be stopped and freed, and |
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283 | the callback invoked. |
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284 | |
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285 | EV::feed_fd_event ($fd, $revents) |
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286 | $loop->feed_fd_event ($fd, $revents) |
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287 | Feed an event on a file descriptor into EV. EV will react to this |
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288 | call as if the readyness notifications specified by $revents (a |
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289 | combination of "EV::READ" and "EV::WRITE") happened on the file |
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290 | descriptor $fd. |
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291 | |
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292 | EV::feed_signal_event ($signal) |
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293 | Feed a signal event into EV. EV will react to this call as if the |
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294 | signal specified by $signal had occured. |
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295 | |
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296 | EV::set_io_collect_interval $time |
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297 | $loop->set_io_collect_interval ($time) |
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298 | EV::set_timeout_collect_interval $time |
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299 | $loop->set_timeout_collect_interval ($time) |
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300 | These advanced functions set the minimum block interval when polling |
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301 | for I/O events and the minimum wait interval for timer events. See |
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302 | the libev documentation at |
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303 | <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT |
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304 | ROLLING_THE_EVENT_LOOP> (locally installed as EV::libev) for a more |
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305 | detailed discussion. |
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306 | |
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307 | $count = EV::pending_count |
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308 | $count = $loop->pending_count |
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309 | Returns the number of currently pending watchers. |
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310 | |
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311 | EV::invoke_pending |
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312 | $loop->invoke_pending |
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313 | Invoke all currently pending watchers. |
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314 | |
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315 | WATCHER OBJECTS |
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316 | A watcher is an object that gets created to record your interest in some |
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317 | event. For instance, if you want to wait for STDIN to become readable, |
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318 | you would create an EV::io watcher for that: |
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319 | |
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320 | my $watcher = EV::io *STDIN, EV::READ, sub { |
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321 | my ($watcher, $revents) = @_; |
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322 | warn "yeah, STDIN should now be readable without blocking!\n" |
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323 | }; |
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324 | |
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325 | All watchers can be active (waiting for events) or inactive (paused). |
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326 | Only active watchers will have their callbacks invoked. All callbacks |
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327 | will be called with at least two arguments: the watcher and a bitmask of |
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328 | received events. |
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329 | |
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330 | Each watcher type has its associated bit in revents, so you can use the |
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331 | same callback for multiple watchers. The event mask is named after the |
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332 | type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
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333 | EV::periodic sets EV::PERIODIC and so on, with the exception of I/O |
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334 | events (which can set both EV::READ and EV::WRITE bits). |
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335 | |
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336 | In the rare case where one wants to create a watcher but not start it at |
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337 | the same time, each constructor has a variant with a trailing "_ns" in |
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338 | its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. |
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339 | |
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340 | Please note that a watcher will automatically be stopped when the |
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341 | watcher object is destroyed, so you *need* to keep the watcher objects |
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342 | returned by the constructors. |
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343 | |
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344 | Also, all methods changing some aspect of a watcher (->set, ->priority, |
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345 | ->fh and so on) automatically stop and start it again if it is active, |
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346 | which means pending events get lost. |
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347 | |
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348 | COMMON WATCHER METHODS |
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349 | This section lists methods common to all watchers. |
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350 | |
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351 | $w->start |
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352 | Starts a watcher if it isn't active already. Does nothing to an |
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353 | already active watcher. By default, all watchers start out in the |
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354 | active state (see the description of the "_ns" variants if you need |
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355 | stopped watchers). |
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356 | |
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357 | $w->stop |
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358 | Stop a watcher if it is active. Also clear any pending events |
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359 | (events that have been received but that didn't yet result in a |
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360 | callback invocation), regardless of whether the watcher was active |
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361 | or not. |
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362 | |
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363 | $bool = $w->is_active |
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364 | Returns true if the watcher is active, false otherwise. |
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365 | |
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366 | $current_data = $w->data |
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367 | $old_data = $w->data ($new_data) |
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368 | Queries a freely usable data scalar on the watcher and optionally |
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369 | changes it. This is a way to associate custom data with a watcher: |
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370 | |
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371 | my $w = EV::timer 60, 0, sub { |
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372 | warn $_[0]->data; |
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373 | }; |
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374 | $w->data ("print me!"); |
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375 | |
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376 | $current_cb = $w->cb |
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377 | $old_cb = $w->cb ($new_cb) |
|
|
378 | Queries the callback on the watcher and optionally changes it. You |
|
|
379 | can do this at any time without the watcher restarting. |
|
|
380 | |
|
|
381 | $current_priority = $w->priority |
|
|
382 | $old_priority = $w->priority ($new_priority) |
|
|
383 | Queries the priority on the watcher and optionally changes it. |
|
|
384 | Pending watchers with higher priority will be invoked first. The |
|
|
385 | valid range of priorities lies between EV::MAXPRI (default 2) and |
|
|
386 | EV::MINPRI (default -2). If the priority is outside this range it |
|
|
387 | will automatically be normalised to the nearest valid priority. |
|
|
388 | |
|
|
389 | The default priority of any newly-created watcher is 0. |
|
|
390 | |
|
|
391 | Note that the priority semantics have not yet been fleshed out and |
|
|
392 | are subject to almost certain change. |
|
|
393 | |
|
|
394 | $w->invoke ($revents) |
|
|
395 | Call the callback *now* with the given event mask. |
|
|
396 | |
|
|
397 | $w->feed_event ($revents) |
|
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398 | Feed some events on this watcher into EV. EV will react to this call |
|
|
399 | as if the watcher had received the given $revents mask. |
|
|
400 | |
|
|
401 | $revents = $w->clear_pending |
|
|
402 | If the watcher is pending, this function clears its pending status |
|
|
403 | and returns its $revents bitset (as if its callback was invoked). If |
|
|
404 | the watcher isn't pending it does nothing and returns 0. |
|
|
405 | |
|
|
406 | $previous_state = $w->keepalive ($bool) |
|
|
407 | Normally, "EV::loop" will return when there are no active watchers |
|
|
408 | (which is a "deadlock" because no progress can be made anymore). |
|
|
409 | This is convenient because it allows you to start your watchers (and |
|
|
410 | your jobs), call "EV::loop" once and when it returns you know that |
|
|
411 | all your jobs are finished (or they forgot to register some watchers |
|
|
412 | for their task :). |
|
|
413 | |
|
|
414 | Sometimes, however, this gets in your way, for example when the |
|
|
415 | module that calls "EV::loop" (usually the main program) is not the |
|
|
416 | same module as a long-living watcher (for example a DNS client |
|
|
417 | module written by somebody else even). Then you might want any |
|
|
418 | outstanding requests to be handled, but you would not want to keep |
|
|
419 | "EV::loop" from returning just because you happen to have this |
|
|
420 | long-running UDP port watcher. |
|
|
421 | |
|
|
422 | In this case you can clear the keepalive status, which means that |
|
|
423 | even though your watcher is active, it won't keep "EV::loop" from |
|
|
424 | returning. |
|
|
425 | |
|
|
426 | The initial value for keepalive is true (enabled), and you can |
|
|
427 | change it any time. |
|
|
428 | |
|
|
429 | Example: Register an I/O watcher for some UDP socket but do not keep |
|
|
430 | the event loop from running just because of that watcher. |
|
|
431 | |
|
|
432 | my $udp_socket = ... |
|
|
433 | my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; |
|
|
434 | $udp_watcher->keepalive (0); |
|
|
435 | |
|
|
436 | $loop = $w->loop |
|
|
437 | Return the loop that this watcher is attached to. |
|
|
438 | |
|
|
439 | WATCHER TYPES |
|
|
440 | Each of the following subsections describes a single watcher type. |
|
|
441 | |
|
|
442 | I/O WATCHERS - is this file descriptor readable or writable? |
80 | my $w = EV::io $fileno_or_fh, $eventmask, $callback |
443 | $w = EV::io $fileno_or_fh, $eventmask, $callback |
81 | my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
444 | $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
|
|
445 | $w = $loop->io ($fileno_or_fh, $eventmask, $callback) |
|
|
446 | $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback) |
82 | As long as the returned watcher object is alive, call the $callback |
447 | As long as the returned watcher object is alive, call the $callback |
83 | when the events specified in $eventmask happen. Initially, the |
448 | when at least one of events specified in $eventmask occurs. |
84 | timeout is disabled. |
|
|
85 | |
449 | |
86 | Youc an additionall set a timeout to occur on the watcher, but note |
|
|
87 | that this timeout will not be reset when you get an I/O event in the |
|
|
88 | EV::PERSIST case, and reaching a timeout will always stop the |
|
|
89 | watcher even in the EV::PERSIST case. |
|
|
90 | |
|
|
91 | If you want a timeout to occur only after a specific time of |
|
|
92 | inactivity, set a repeating timeout and do NOT use EV::PERSIST. |
|
|
93 | |
|
|
94 | Eventmask can be one or more of these constants ORed together: |
450 | The $eventmask can be one or more of these constants ORed together: |
95 | |
451 | |
96 | EV::READ wait until read() wouldn't block anymore |
452 | EV::READ wait until read() wouldn't block anymore |
97 | EV::WRITE wait until write() wouldn't block anymore |
453 | EV::WRITE wait until write() wouldn't block anymore |
98 | EV::PERSIST stay active after a (non-timeout) event occured |
|
|
99 | |
454 | |
100 | The "io_ns" variant doesn't add/start the newly created watcher. |
455 | The "io_ns" variant doesn't start (activate) the newly created |
101 | |
|
|
102 | my $w = EV::timer $after, $repeat, $callback |
|
|
103 | my $w = EV::timer_ns $after, $repeat, $callback |
|
|
104 | Calls the callback after $after seconds. If $repeat is true, the |
|
|
105 | timer will be restarted after the callback returns. This means that |
|
|
106 | the callback would be called roughly every $after seconds, prolonged |
|
|
107 | by the time the callback takes. |
|
|
108 | |
|
|
109 | The "timer_ns" variant doesn't add/start the newly created watcher. |
|
|
110 | |
|
|
111 | my $w = EV::timer_abs $at, $interval, $callback |
|
|
112 | my $w = EV::timer_abs_ns $at, $interval, $callback |
|
|
113 | Similar to EV::timer, but the time is given as an absolute point in |
|
|
114 | time ($at), plus an optional $interval. |
|
|
115 | |
|
|
116 | If the $interval is zero, then the callback will be called at the |
|
|
117 | time $at if that is in the future, or as soon as possible if its in |
|
|
118 | the past. It will not automatically repeat. |
|
|
119 | |
|
|
120 | If the $interval is nonzero, then the watcher will always be |
|
|
121 | scheduled to time out at the next "$at + integer * $interval" time. |
|
|
122 | |
|
|
123 | This can be used to schedule a callback to run at very regular |
|
|
124 | intervals, as long as the processing time is less then the interval |
|
|
125 | (otherwise obviously events will be skipped). |
|
|
126 | |
|
|
127 | Another way to think about it (for the mathematically inclined) is |
|
|
128 | that "timer_abs" will try to tun the callback at the next possible |
|
|
129 | time where "$time = $at (mod $interval)", regardless of any time |
|
|
130 | jumps. |
|
|
131 | |
|
|
132 | The "timer_abs_ns" variant doesn't add/start the newly created |
|
|
133 | watcher. |
456 | watcher. |
134 | |
457 | |
135 | my $w = EV::signal $signum, $callback |
458 | $w->set ($fileno_or_fh, $eventmask) |
136 | my $w = EV::signal_ns $signum, $callback |
459 | Reconfigures the watcher, see the constructor above for details. Can |
137 | Call the callback when signal $signum is received. |
460 | be called at any time. |
138 | |
|
|
139 | The "signal_ns" variant doesn't add/start the newly created watcher. |
|
|
140 | |
|
|
141 | THE EV::Event CLASS |
|
|
142 | All EV functions creating an event watcher (designated by "my $w =" |
|
|
143 | above) support the following methods on the returned watcher object: |
|
|
144 | |
|
|
145 | $w->add ($timeout) |
|
|
146 | Stops and (re-)starts the event watcher, setting the optional |
|
|
147 | timeout to the given value, or clearing the timeout if none is |
|
|
148 | given. |
|
|
149 | |
|
|
150 | $w->start |
|
|
151 | Stops and (re-)starts the event watcher without touching the |
|
|
152 | timeout. |
|
|
153 | |
|
|
154 | $w->del |
|
|
155 | $w->stop |
|
|
156 | Stop the event watcher if it was started. |
|
|
157 | |
|
|
158 | $current_callback = $w->cb |
|
|
159 | $old_callback = $w->cb ($new_callback) |
|
|
160 | Return the previously set callback and optionally set a new one. |
|
|
161 | |
461 | |
162 | $current_fh = $w->fh |
462 | $current_fh = $w->fh |
163 | $old_fh = $w->fh ($new_fh) |
463 | $old_fh = $w->fh ($new_fh) |
164 | Returns the previously set filehandle and optionally set a new one. |
464 | Returns the previously set filehandle and optionally set a new one. |
165 | |
465 | |
166 | $current_eventmask = $w->events |
466 | $current_eventmask = $w->events |
167 | $old_eventmask = $w->events ($new_eventmask) |
467 | $old_eventmask = $w->events ($new_eventmask) |
168 | Returns the previously set event mask and optionally set a new one. |
468 | Returns the previously set event mask and optionally set a new one. |
169 | |
469 | |
|
|
470 | TIMER WATCHERS - relative and optionally repeating timeouts |
|
|
471 | $w = EV::timer $after, $repeat, $callback |
|
|
472 | $w = EV::timer_ns $after, $repeat, $callback |
|
|
473 | $w = $loop->timer ($after, $repeat, $callback) |
|
|
474 | $w = $loop->timer_ns ($after, $repeat, $callback) |
|
|
475 | Calls the callback after $after seconds (which may be fractional). |
|
|
476 | If $repeat is non-zero, the timer will be restarted (with the |
|
|
477 | $repeat value as $after) after the callback returns. |
|
|
478 | |
|
|
479 | This means that the callback would be called roughly after $after |
|
|
480 | seconds, and then every $repeat seconds. The timer does his best not |
|
|
481 | to drift, but it will not invoke the timer more often then once per |
|
|
482 | event loop iteration, and might drift in other cases. If that isn't |
|
|
483 | acceptable, look at EV::periodic, which can provide long-term stable |
|
|
484 | timers. |
|
|
485 | |
|
|
486 | The timer is based on a monotonic clock, that is, if somebody is |
|
|
487 | sitting in front of the machine while the timer is running and |
|
|
488 | changes the system clock, the timer will nevertheless run (roughly) |
|
|
489 | the same time. |
|
|
490 | |
|
|
491 | The "timer_ns" variant doesn't start (activate) the newly created |
|
|
492 | watcher. |
|
|
493 | |
170 | $w->timeout ($after, $repeat) |
494 | $w->set ($after, $repeat) |
171 | Resets the timeout (see "EV::timer" for details). |
495 | Reconfigures the watcher, see the constructor above for details. Can |
|
|
496 | be called at any time. |
172 | |
497 | |
|
|
498 | $w->again |
|
|
499 | Similar to the "start" method, but has special semantics for |
|
|
500 | repeating timers: |
|
|
501 | |
|
|
502 | If the timer is active and non-repeating, it will be stopped. |
|
|
503 | |
|
|
504 | If the timer is active and repeating, reset the timeout to occur |
|
|
505 | $repeat seconds after now. |
|
|
506 | |
|
|
507 | If the timer is inactive and repeating, start it using the repeat |
|
|
508 | value. |
|
|
509 | |
|
|
510 | Otherwise do nothing. |
|
|
511 | |
|
|
512 | This behaviour is useful when you have a timeout for some IO |
|
|
513 | operation. You create a timer object with the same value for $after |
|
|
514 | and $repeat, and then, in the read/write watcher, run the "again" |
|
|
515 | method on the timeout. |
|
|
516 | |
|
|
517 | PERIODIC WATCHERS - to cron or not to cron? |
|
|
518 | $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
|
|
519 | $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
|
|
520 | $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback) |
|
|
521 | $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback) |
|
|
522 | Similar to EV::timer, but is not based on relative timeouts but on |
|
|
523 | absolute times. Apart from creating "simple" timers that trigger |
|
|
524 | "at" the specified time, it can also be used for non-drifting |
|
|
525 | absolute timers and more complex, cron-like, setups that are not |
|
|
526 | adversely affected by time jumps (i.e. when the system clock is |
|
|
527 | changed by explicit date -s or other means such as ntpd). It is also |
|
|
528 | the most complex watcher type in EV. |
|
|
529 | |
|
|
530 | It has three distinct "modes": |
|
|
531 | |
|
|
532 | * absolute timer ($interval = $reschedule_cb = 0) |
|
|
533 | |
|
|
534 | This time simply fires at the wallclock time $at and doesn't |
|
|
535 | repeat. It will not adjust when a time jump occurs, that is, if |
|
|
536 | it is to be run at January 1st 2011 then it will run when the |
|
|
537 | system time reaches or surpasses this time. |
|
|
538 | |
|
|
539 | * repeating interval timer ($interval > 0, $reschedule_cb = 0) |
|
|
540 | |
|
|
541 | In this mode the watcher will always be scheduled to time out at |
|
|
542 | the next "$at + N * $interval" time (for some integer N) and |
|
|
543 | then repeat, regardless of any time jumps. |
|
|
544 | |
|
|
545 | This can be used to create timers that do not drift with respect |
|
|
546 | to system time: |
|
|
547 | |
|
|
548 | my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; |
|
|
549 | |
|
|
550 | That doesn't mean there will always be 3600 seconds in between |
|
|
551 | triggers, but only that the the clalback will be called when the |
|
|
552 | system time shows a full hour (UTC). |
|
|
553 | |
|
|
554 | Another way to think about it (for the mathematically inclined) |
|
|
555 | is that EV::periodic will try to run the callback in this mode |
|
|
556 | at the next possible time where "$time = $at (mod $interval)", |
|
|
557 | regardless of any time jumps. |
|
|
558 | |
|
|
559 | * manual reschedule mode ($reschedule_cb = coderef) |
|
|
560 | |
|
|
561 | In this mode $interval and $at are both being ignored. Instead, |
|
|
562 | each time the periodic watcher gets scheduled, the reschedule |
|
|
563 | callback ($reschedule_cb) will be called with the watcher as |
|
|
564 | first, and the current time as second argument. |
|
|
565 | |
|
|
566 | *This callback MUST NOT stop or destroy this or any other |
|
|
567 | periodic watcher, ever, and MUST NOT call any event loop |
|
|
568 | functions or methods*. If you need to stop it, return 1e30 and |
|
|
569 | stop it afterwards. You may create and start a "EV::prepare" |
|
|
570 | watcher for this task. |
|
|
571 | |
|
|
572 | It must return the next time to trigger, based on the passed |
|
|
573 | time value (that is, the lowest time value larger than or equal |
|
|
574 | to to the second argument). It will usually be called just |
|
|
575 | before the callback will be triggered, but might be called at |
|
|
576 | other times, too. |
|
|
577 | |
|
|
578 | This can be used to create very complex timers, such as a timer |
|
|
579 | that triggers on each midnight, local time (actually 24 hours |
|
|
580 | after the last midnight, to keep the example simple. If you know |
|
|
581 | a way to do it correctly in about the same space (without |
|
|
582 | requiring elaborate modules), drop me a note :): |
|
|
583 | |
|
|
584 | my $daily = EV::periodic 0, 0, sub { |
|
|
585 | my ($w, $now) = @_; |
|
|
586 | |
|
|
587 | use Time::Local (); |
|
|
588 | my (undef, undef, undef, $d, $m, $y) = localtime $now; |
|
|
589 | 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y |
|
|
590 | }, sub { |
|
|
591 | print "it's midnight or likely shortly after, now\n"; |
|
|
592 | }; |
|
|
593 | |
|
|
594 | The "periodic_ns" variant doesn't start (activate) the newly created |
|
|
595 | watcher. |
|
|
596 | |
|
|
597 | $w->set ($at, $interval, $reschedule_cb) |
|
|
598 | Reconfigures the watcher, see the constructor above for details. Can |
|
|
599 | be called at any time. |
|
|
600 | |
|
|
601 | $w->again |
|
|
602 | Simply stops and starts the watcher again. |
|
|
603 | |
|
|
604 | $time = $w->at |
|
|
605 | Return the time that the watcher is expected to trigger next. |
|
|
606 | |
|
|
607 | SIGNAL WATCHERS - signal me when a signal gets signalled! |
|
|
608 | $w = EV::signal $signal, $callback |
|
|
609 | $w = EV::signal_ns $signal, $callback |
|
|
610 | $w = $loop->signal ($signal, $callback) |
|
|
611 | $w = $loop->signal_ns ($signal, $callback) |
|
|
612 | Call the callback when $signal is received (the signal can be |
|
|
613 | specified by number or by name, just as with "kill" or %SIG). |
|
|
614 | |
|
|
615 | Only one event loop can grab a given signal - attempting to grab the |
|
|
616 | same signal from two EV loops will crash the program immediately or |
|
|
617 | cause data corruption. |
|
|
618 | |
|
|
619 | EV will grab the signal for the process (the kernel only allows one |
|
|
620 | component to receive a signal at a time) when you start a signal |
|
|
621 | watcher, and removes it again when you stop it. Perl does the same |
|
|
622 | when you add/remove callbacks to %SIG, so watch out. |
|
|
623 | |
|
|
624 | You can have as many signal watchers per signal as you want. |
|
|
625 | |
|
|
626 | The "signal_ns" variant doesn't start (activate) the newly created |
|
|
627 | watcher. |
|
|
628 | |
|
|
629 | $w->set ($signal) |
|
|
630 | Reconfigures the watcher, see the constructor above for details. Can |
|
|
631 | be called at any time. |
|
|
632 | |
|
|
633 | $current_signum = $w->signal |
|
|
634 | $old_signum = $w->signal ($new_signal) |
|
|
635 | Returns the previously set signal (always as a number not name) and |
|
|
636 | optionally set a new one. |
|
|
637 | |
|
|
638 | CHILD WATCHERS - watch out for process status changes |
|
|
639 | $w = EV::child $pid, $trace, $callback |
|
|
640 | $w = EV::child_ns $pid, $trace, $callback |
|
|
641 | $w = $loop->child ($pid, $trace, $callback) |
|
|
642 | $w = $loop->child_ns ($pid, $trace, $callback) |
|
|
643 | Call the callback when a status change for pid $pid (or any pid if |
|
|
644 | $pid is 0) has been received (a status change happens when the |
|
|
645 | process terminates or is killed, or, when trace is true, |
|
|
646 | additionally when it is stopped or continued). More precisely: when |
|
|
647 | the process receives a "SIGCHLD", EV will fetch the outstanding |
|
|
648 | exit/wait status for all changed/zombie children and call the |
|
|
649 | callback. |
|
|
650 | |
|
|
651 | It is valid (and fully supported) to install a child watcher after a |
|
|
652 | child has exited but before the event loop has started its next |
|
|
653 | iteration (for example, first you "fork", then the new child process |
|
|
654 | might exit, and only then do you install a child watcher in the |
|
|
655 | parent for the new pid). |
|
|
656 | |
|
|
657 | You can access both exit (or tracing) status and pid by using the |
|
|
658 | "rstatus" and "rpid" methods on the watcher object. |
|
|
659 | |
|
|
660 | You can have as many pid watchers per pid as you want, they will all |
|
|
661 | be called. |
|
|
662 | |
|
|
663 | The "child_ns" variant doesn't start (activate) the newly created |
|
|
664 | watcher. |
|
|
665 | |
|
|
666 | $w->set ($pid, $trace) |
|
|
667 | Reconfigures the watcher, see the constructor above for details. Can |
|
|
668 | be called at any time. |
|
|
669 | |
|
|
670 | $current_pid = $w->pid |
|
|
671 | Returns the previously set process id and optionally set a new one. |
|
|
672 | |
|
|
673 | $exit_status = $w->rstatus |
|
|
674 | Return the exit/wait status (as returned by waitpid, see the waitpid |
|
|
675 | entry in perlfunc). |
|
|
676 | |
|
|
677 | $pid = $w->rpid |
|
|
678 | Return the pid of the awaited child (useful when you have installed |
|
|
679 | a watcher for all pids). |
|
|
680 | |
|
|
681 | STAT WATCHERS - did the file attributes just change? |
|
|
682 | $w = EV::stat $path, $interval, $callback |
|
|
683 | $w = EV::stat_ns $path, $interval, $callback |
|
|
684 | $w = $loop->stat ($path, $interval, $callback) |
|
|
685 | $w = $loop->stat_ns ($path, $interval, $callback) |
|
|
686 | Call the callback when a file status change has been detected on |
|
|
687 | $path. The $path does not need to exist, changing from "path exists" |
|
|
688 | to "path does not exist" is a status change like any other. |
|
|
689 | |
|
|
690 | The $interval is a recommended polling interval for systems where |
|
|
691 | OS-supported change notifications don't exist or are not supported. |
|
|
692 | If you use 0 then an unspecified default is used (which is highly |
|
|
693 | recommended!), which is to be expected to be around five seconds |
|
|
694 | usually. |
|
|
695 | |
|
|
696 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
697 | as even with OS-supported change notifications, this can be |
|
|
698 | resource-intensive. |
|
|
699 | |
|
|
700 | The "stat_ns" variant doesn't start (activate) the newly created |
|
|
701 | watcher. |
|
|
702 | |
|
|
703 | ... = $w->stat |
|
|
704 | This call is very similar to the perl "stat" built-in: It stats |
|
|
705 | (using "lstat") the path specified in the watcher and sets perls |
|
|
706 | stat cache (as well as EV's idea of the current stat values) to the |
|
|
707 | values found. |
|
|
708 | |
|
|
709 | In scalar context, a boolean is return indicating success or failure |
|
|
710 | of the stat. In list context, the same 13-value list as with stat is |
|
|
711 | returned (except that the blksize and blocks fields are not |
|
|
712 | reliable). |
|
|
713 | |
|
|
714 | In the case of an error, errno is set to "ENOENT" (regardless of the |
|
|
715 | actual error value) and the "nlink" value is forced to zero (if the |
|
|
716 | stat was successful then nlink is guaranteed to be non-zero). |
|
|
717 | |
|
|
718 | See also the next two entries for more info. |
|
|
719 | |
|
|
720 | ... = $w->attr |
|
|
721 | Just like "$w->stat", but without the initial stat'ing: this returns |
|
|
722 | the values most recently detected by EV. See the next entry for more |
|
|
723 | info. |
|
|
724 | |
|
|
725 | ... = $w->prev |
|
|
726 | Just like "$w->stat", but without the initial stat'ing: this returns |
|
|
727 | the previous set of values, before the change. |
|
|
728 | |
|
|
729 | That is, when the watcher callback is invoked, "$w->prev" will be |
|
|
730 | set to the values found *before* a change was detected, while |
|
|
731 | "$w->attr" returns the values found leading to the change detection. |
|
|
732 | The difference (if any) between "prev" and "attr" is what triggered |
|
|
733 | the callback. |
|
|
734 | |
|
|
735 | If you did something to the filesystem object and do not want to |
|
|
736 | trigger yet another change, you can call "stat" to update EV's idea |
|
|
737 | of what the current attributes are. |
|
|
738 | |
173 | $w->timeout_abs ($at, $interval) |
739 | $w->set ($path, $interval) |
174 | Resets the timeout (see "EV::timer_abs" for details). |
740 | Reconfigures the watcher, see the constructor above for details. Can |
|
|
741 | be called at any time. |
175 | |
742 | |
176 | $w->priority_set ($priority) |
743 | $current_path = $w->path |
177 | Set the priority of the watcher to $priority (0 <= $priority < |
744 | $old_path = $w->path ($new_path) |
178 | $EV::NPRI). |
745 | Returns the previously set path and optionally set a new one. |
179 | |
746 | |
180 | BUGS |
747 | $current_interval = $w->interval |
181 | Lots. Libevent itself isn't well tested and rather buggy, and this |
748 | $old_interval = $w->interval ($new_interval) |
182 | module is quite new at the moment. |
749 | Returns the previously set interval and optionally set a new one. |
|
|
750 | Can be used to query the actual interval used. |
183 | |
751 | |
184 | Please note that the epoll method is not, in general, reliable in |
752 | IDLE WATCHERS - when you've got nothing better to do... |
185 | programs that use fork (even if no libveent calls are being made in the |
753 | $w = EV::idle $callback |
186 | forked process). If your program behaves erratically, try setting the |
754 | $w = EV::idle_ns $callback |
187 | environment variable "EVENT_NOEPOLL" first when running the program. |
755 | $w = $loop->idle ($callback) |
|
|
756 | $w = $loop->idle_ns ($callback) |
|
|
757 | Call the callback when there are no other pending watchers of the |
|
|
758 | same or higher priority (excluding check, prepare and other idle |
|
|
759 | watchers of the same or lower priority, of course). They are called |
|
|
760 | idle watchers because when the watcher is the highest priority |
|
|
761 | pending event in the process, the process is considered to be idle |
|
|
762 | at that priority. |
188 | |
763 | |
189 | In general, if you fork, then you can only use the EV module in one of |
764 | If you want a watcher that is only ever called when *no* other |
190 | the children. |
765 | events are outstanding you have to set the priority to "EV::MINPRI". |
|
|
766 | |
|
|
767 | The process will not block as long as any idle watchers are active, |
|
|
768 | and they will be called repeatedly until stopped. |
|
|
769 | |
|
|
770 | For example, if you have idle watchers at priority 0 and 1, and an |
|
|
771 | I/O watcher at priority 0, then the idle watcher at priority 1 and |
|
|
772 | the I/O watcher will always run when ready. Only when the idle |
|
|
773 | watcher at priority 1 is stopped and the I/O watcher at priority 0 |
|
|
774 | is not pending with the 0-priority idle watcher be invoked. |
|
|
775 | |
|
|
776 | The "idle_ns" variant doesn't start (activate) the newly created |
|
|
777 | watcher. |
|
|
778 | |
|
|
779 | PREPARE WATCHERS - customise your event loop! |
|
|
780 | $w = EV::prepare $callback |
|
|
781 | $w = EV::prepare_ns $callback |
|
|
782 | $w = $loop->prepare ($callback) |
|
|
783 | $w = $loop->prepare_ns ($callback) |
|
|
784 | Call the callback just before the process would block. You can still |
|
|
785 | create/modify any watchers at this point. |
|
|
786 | |
|
|
787 | See the EV::check watcher, below, for explanations and an example. |
|
|
788 | |
|
|
789 | The "prepare_ns" variant doesn't start (activate) the newly created |
|
|
790 | watcher. |
|
|
791 | |
|
|
792 | CHECK WATCHERS - customise your event loop even more! |
|
|
793 | $w = EV::check $callback |
|
|
794 | $w = EV::check_ns $callback |
|
|
795 | $w = $loop->check ($callback) |
|
|
796 | $w = $loop->check_ns ($callback) |
|
|
797 | Call the callback just after the process wakes up again (after it |
|
|
798 | has gathered events), but before any other callbacks have been |
|
|
799 | invoked. |
|
|
800 | |
|
|
801 | This can be used to integrate other event-based software into the EV |
|
|
802 | mainloop: You register a prepare callback and in there, you create |
|
|
803 | io and timer watchers as required by the other software. Here is a |
|
|
804 | real-world example of integrating Net::SNMP (with some details left |
|
|
805 | out): |
|
|
806 | |
|
|
807 | our @snmp_watcher; |
|
|
808 | |
|
|
809 | our $snmp_prepare = EV::prepare sub { |
|
|
810 | # do nothing unless active |
|
|
811 | $dispatcher->{_event_queue_h} |
|
|
812 | or return; |
|
|
813 | |
|
|
814 | # make the dispatcher handle any outstanding stuff |
|
|
815 | ... not shown |
|
|
816 | |
|
|
817 | # create an I/O watcher for each and every socket |
|
|
818 | @snmp_watcher = ( |
|
|
819 | (map { EV::io $_, EV::READ, sub { } } |
|
|
820 | keys %{ $dispatcher->{_descriptors} }), |
|
|
821 | |
|
|
822 | EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] |
|
|
823 | ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0), |
|
|
824 | 0, sub { }, |
|
|
825 | ); |
|
|
826 | }; |
|
|
827 | |
|
|
828 | The callbacks are irrelevant (and are not even being called), the |
|
|
829 | only purpose of those watchers is to wake up the process as soon as |
|
|
830 | one of those events occurs (socket readable, or timer timed out). |
|
|
831 | The corresponding EV::check watcher will then clean up: |
|
|
832 | |
|
|
833 | our $snmp_check = EV::check sub { |
|
|
834 | # destroy all watchers |
|
|
835 | @snmp_watcher = (); |
|
|
836 | |
|
|
837 | # make the dispatcher handle any new stuff |
|
|
838 | ... not shown |
|
|
839 | }; |
|
|
840 | |
|
|
841 | The callbacks of the created watchers will not be called as the |
|
|
842 | watchers are destroyed before this can happen (remember EV::check |
|
|
843 | gets called first). |
|
|
844 | |
|
|
845 | The "check_ns" variant doesn't start (activate) the newly created |
|
|
846 | watcher. |
|
|
847 | |
|
|
848 | EV::CHECK constant issues |
|
|
849 | Like all other watcher types, there is a bitmask constant for use in |
|
|
850 | $revents and other places. The "EV::CHECK" is special as it has the |
|
|
851 | same name as the "CHECK" sub called by Perl. This doesn't cause big |
|
|
852 | issues on newer perls (beginning with 5.8.9), but it means thatthe |
|
|
853 | constant must be *inlined*, i.e. runtime calls will not work. That |
|
|
854 | means that as long as you always "use EV" and then "EV::CHECK" you |
|
|
855 | are on the safe side. |
|
|
856 | |
|
|
857 | FORK WATCHERS - the audacity to resume the event loop after a fork |
|
|
858 | Fork watchers are called when a "fork ()" was detected. The invocation |
|
|
859 | is done before the event loop blocks next and before "check" watchers |
|
|
860 | are being called, and only in the child after the fork. |
|
|
861 | |
|
|
862 | $w = EV::fork $callback |
|
|
863 | $w = EV::fork_ns $callback |
|
|
864 | $w = $loop->fork ($callback) |
|
|
865 | $w = $loop->fork_ns ($callback) |
|
|
866 | Call the callback before the event loop is resumed in the child |
|
|
867 | process after a fork. |
|
|
868 | |
|
|
869 | The "fork_ns" variant doesn't start (activate) the newly created |
|
|
870 | watcher. |
|
|
871 | |
|
|
872 | EMBED WATCHERS - when one backend isn't enough... |
|
|
873 | This is a rather advanced watcher type that lets you embed one event |
|
|
874 | loop into another (currently only IO events are supported in the |
|
|
875 | embedded loop, other types of watchers might be handled in a delayed or |
|
|
876 | incorrect fashion and must not be used). |
|
|
877 | |
|
|
878 | See the libev documentation at |
|
|
879 | <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code |
|
|
880 | _when_one_backend_> (locally installed as EV::libev) for more details. |
|
|
881 | |
|
|
882 | In short, this watcher is most useful on BSD systems without working |
|
|
883 | kqueue to still be able to handle a large number of sockets: |
|
|
884 | |
|
|
885 | my $socket_loop; |
|
|
886 | |
|
|
887 | # check wether we use SELECT or POLL _and_ KQUEUE is supported |
|
|
888 | if ( |
|
|
889 | (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT)) |
|
|
890 | && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE) |
|
|
891 | ) { |
|
|
892 | # use kqueue for sockets |
|
|
893 | $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV; |
|
|
894 | } |
|
|
895 | |
|
|
896 | # use the default loop otherwise |
|
|
897 | $socket_loop ||= EV::default_loop; |
|
|
898 | |
|
|
899 | $w = EV::embed $otherloop[, $callback] |
|
|
900 | $w = EV::embed_ns $otherloop[, $callback] |
|
|
901 | $w = $loop->embed ($otherloop[, $callback]) |
|
|
902 | $w = $loop->embed_ns ($otherloop[, $callback]) |
|
|
903 | Call the callback when the embedded event loop ($otherloop) has any |
|
|
904 | I/O activity. The $callback is optional: if it is missing, then the |
|
|
905 | embedded event loop will be managed automatically (which is |
|
|
906 | recommended), otherwise you have to invoke "sweep" yourself. |
|
|
907 | |
|
|
908 | The "embed_ns" variant doesn't start (activate) the newly created |
|
|
909 | watcher. |
|
|
910 | |
|
|
911 | ASYNC WATCHERS - how to wake up another event loop |
|
|
912 | Async watchers are provided by EV, but have little use in perl directly, |
|
|
913 | as perl neither supports threads running in parallel nor direct access |
|
|
914 | to signal handlers or other contexts where they could be of value. |
|
|
915 | |
|
|
916 | It is, however, possible to use them from the XS level. |
|
|
917 | |
|
|
918 | Please see the libev documentation for further details. |
|
|
919 | |
|
|
920 | $w = EV::async $callback |
|
|
921 | $w = EV::async_ns $callback |
|
|
922 | $w->send |
|
|
923 | $bool = $w->async_pending |
|
|
924 | |
|
|
925 | PERL SIGNALS |
|
|
926 | While Perl signal handling (%SIG) is not affected by EV, the behaviour |
|
|
927 | with EV is as the same as any other C library: Perl-signals will only be |
|
|
928 | handled when Perl runs, which means your signal handler might be invoked |
|
|
929 | only the next time an event callback is invoked. |
|
|
930 | |
|
|
931 | The solution is to use EV signal watchers (see "EV::signal"), which will |
|
|
932 | ensure proper operations with regards to other event watchers. |
|
|
933 | |
|
|
934 | If you cannot do this for whatever reason, you can also force a watcher |
|
|
935 | to be called on every event loop iteration by installing a "EV::check" |
|
|
936 | watcher: |
|
|
937 | |
|
|
938 | my $async_check = EV::check sub { }; |
|
|
939 | |
|
|
940 | This ensures that perl gets into control for a short time to handle any |
|
|
941 | pending signals, and also ensures (slightly) slower overall operation. |
|
|
942 | |
|
|
943 | ITHREADS |
|
|
944 | Ithreads are not supported by this module in any way. Perl |
|
|
945 | pseudo-threads is evil stuff and must die. Real threads as provided by |
|
|
946 | Coro are fully supported (and enhanced support is available via |
|
|
947 | Coro::EV). |
|
|
948 | |
|
|
949 | FORK |
|
|
950 | Most of the "improved" event delivering mechanisms of modern operating |
|
|
951 | systems have quite a few problems with fork(2) (to put it bluntly: it is |
|
|
952 | not supported and usually destructive). Libev makes it possible to work |
|
|
953 | around this by having a function that recreates the kernel state after |
|
|
954 | fork in the child. |
|
|
955 | |
|
|
956 | On non-win32 platforms, this module requires the pthread_atfork |
|
|
957 | functionality to do this automatically for you. This function is quite |
|
|
958 | buggy on most BSDs, though, so YMMV. The overhead for this is quite |
|
|
959 | negligible, because everything the function currently does is set a flag |
|
|
960 | that is checked only when the event loop gets used the next time, so |
|
|
961 | when you do fork but not use EV, the overhead is minimal. |
|
|
962 | |
|
|
963 | On win32, there is no notion of fork so all this doesn't apply, of |
|
|
964 | course. |
191 | |
965 | |
192 | SEE ALSO |
966 | SEE ALSO |
193 | L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>. |
967 | EV::MakeMaker - MakeMaker interface to XS API, EV::ADNS (asynchronous |
194 | L<EV::AnyEvent>. |
968 | DNS), Glib::EV (makes Glib/Gtk2 use EV as event loop), EV::Glib (embed |
|
|
969 | Glib into EV), Coro::EV (efficient thread integration), Net::SNMP::EV |
|
|
970 | (asynchronous SNMP), AnyEvent for event-loop agnostic and portable event |
|
|
971 | driven programming. |
195 | |
972 | |
196 | AUTHOR |
973 | AUTHOR |
197 | Marc Lehmann <schmorp@schmorp.de> |
974 | Marc Lehmann <schmorp@schmorp.de> |
198 | http://home.schmorp.de/ |
975 | http://home.schmorp.de/ |
199 | |
976 | |