1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | EV - perl interface to libevent, monkey.org/~provos/libevent/ |
3 | EV - perl interface to libev, a high performance full-featured event loop |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use EV; |
7 | use EV; |
8 | |
8 | |
9 | # TIMER |
9 | # TIMERS |
10 | |
10 | |
11 | my $w = EV::timer 2, 0, sub { |
11 | my $w = EV::timer 2, 0, sub { |
12 | warn "is called after 2s"; |
12 | warn "is called after 2s"; |
13 | }; |
13 | }; |
14 | |
14 | |
15 | my $w = EV::timer 2, 1, sub { |
15 | my $w = EV::timer 2, 2, sub { |
16 | warn "is called roughly every 2s (repeat = 1)"; |
16 | warn "is called roughly every 2s (repeat = 2)"; |
17 | }; |
17 | }; |
18 | |
18 | |
19 | undef $w; # destroy event watcher again |
19 | undef $w; # destroy event watcher again |
20 | |
20 | |
21 | # IO |
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22 | |
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23 | my $w = EV::timer_abs 0, 60, sub { |
21 | my $w = EV::periodic 0, 60, 0, sub { |
24 | warn "is called every minute, on the minute, exactly"; |
22 | warn "is called every minute, on the minute, exactly"; |
25 | }; |
23 | }; |
26 | |
24 | |
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25 | # IO |
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26 | |
27 | my $w = EV::io \*STDIN, EV::READ | EV::PERSIST, sub { |
27 | my $w = EV::io *STDIN, EV::READ, sub { |
28 | my ($w, $events) = @_; # all callbacks get the watcher object and event mask |
28 | my ($w, $revents) = @_; # all callbacks receive the watcher and event mask |
29 | if ($events & EV::TIMEOUT) { |
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30 | warn "nothign received on stdin for 10 seconds, retrying"; |
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31 | } else { |
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32 | warn "stdin is readable, you entered: ", <STDIN>; |
29 | warn "stdin is readable, you entered: ", <STDIN>; |
33 | } |
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34 | }; |
30 | }; |
35 | $w->timeout (10); |
31 | |
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32 | # SIGNALS |
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33 | |
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34 | my $w = EV::signal 'QUIT', sub { |
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35 | warn "sigquit received\n"; |
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36 | }; |
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37 | |
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38 | # CHILD/PID STATUS CHANGES |
36 | |
39 | |
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40 | my $w = EV::child 666, sub { |
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41 | my ($w, $revents) = @_; |
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42 | my $status = $w->rstatus; |
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43 | }; |
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44 | |
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45 | # STAT CHANGES |
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46 | my $w = EV::stat "/etc/passwd", 10, sub { |
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47 | my ($w, $revents) = @_; |
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48 | warn $w->path, " has changed somehow.\n"; |
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49 | }; |
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50 | |
37 | # MAINLOOP |
51 | # MAINLOOP |
38 | EV::dispatch; # loop as long as watchers are active |
52 | EV::loop; # loop until EV::unloop is called or all watchers stop |
39 | EV::loop; # the same thing |
53 | EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
40 | EV::loop EV::LOOP_ONCE; |
54 | EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
41 | EV::loop EV::LOOP_ONSHOT; |
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42 | |
55 | |
43 | =head1 DESCRIPTION |
56 | =head1 DESCRIPTION |
44 | |
57 | |
45 | This module provides an interface to libevent |
58 | This module provides an interface to libev |
46 | (L<http://monkey.org/~provos/libevent/>). You probably should acquaint |
59 | (L<http://software.schmorp.de/pkg/libev.html>). While the documentation |
47 | yourself with its documentation and source code to be able to use this |
60 | below is comprehensive, one might also consult the documentation of libev |
48 | module fully. |
61 | itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on |
49 | |
62 | watcher semantics or some discussion on the available backends, or how to |
50 | Please note thta this module disables the libevent EPOLL method by |
63 | force a specific backend with C<LIBEV_FLAGS>, or just about in any case |
51 | default, see BUGS, below, if you need to enable it. |
64 | because it has much more detailed information. |
52 | |
65 | |
53 | =cut |
66 | =cut |
54 | |
67 | |
55 | package EV; |
68 | package EV; |
56 | |
69 | |
57 | use strict; |
70 | use strict; |
58 | |
71 | |
59 | BEGIN { |
72 | BEGIN { |
60 | our $VERSION = '0.01'; |
73 | our $VERSION = '1.7'; |
61 | use XSLoader; |
74 | use XSLoader; |
62 | XSLoader::load "EV", $VERSION; |
75 | XSLoader::load "EV", $VERSION; |
63 | } |
76 | } |
64 | |
77 | |
65 | =head1 FUNCTIONAL INTERFACE |
78 | @EV::IO::ISA = |
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79 | @EV::Timer::ISA = |
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80 | @EV::Periodic::ISA = |
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81 | @EV::Signal::ISA = |
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82 | @EV::Child::ISA = |
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83 | @EV::Stat::ISA = |
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84 | @EV::Idle::ISA = |
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85 | @EV::Prepare::ISA = |
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86 | @EV::Check::ISA = |
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87 | @EV::Embed::ISA = |
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88 | @EV::Fork::ISA = |
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89 | "EV::Watcher"; |
66 | |
90 | |
67 | =over 4 |
91 | =head1 BASIC INTERFACE |
68 | |
92 | |
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93 | =over 4 |
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94 | |
69 | =item $EV::NPRI |
95 | =item $EV::DIED |
70 | |
96 | |
71 | How many priority levels are available. |
97 | Must contain a reference to a function that is called when a callback |
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98 | throws an exception (with $@ containing thr error). The default prints an |
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99 | informative message and continues. |
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100 | |
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101 | If this callback throws an exception it will be silently ignored. |
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102 | |
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103 | =item $time = EV::time |
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104 | |
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105 | Returns the current time in (fractional) seconds since the epoch. |
72 | |
106 | |
73 | =item $time = EV::now |
107 | =item $time = EV::now |
74 | |
108 | |
75 | Returns the time in (fractional) seconds since the epoch. |
109 | Returns the time the last event loop iteration has been started. This |
76 | |
110 | is the time that (relative) timers are based on, and refering to it is |
77 | =item $version = EV::version |
111 | usually faster then calling EV::time. |
78 | |
112 | |
79 | =item $method = EV::method |
113 | =item $method = EV::method |
80 | |
114 | |
81 | Return version string and event polling method used. |
115 | Returns an integer describing the backend used by libev (EV::METHOD_SELECT |
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116 | or EV::METHOD_EPOLL). |
82 | |
117 | |
83 | =item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT |
118 | =item EV::loop [$flags] |
84 | |
119 | |
85 | =item EV::loopexit $after |
120 | Begin checking for events and calling callbacks. It returns when a |
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121 | callback calls EV::unloop. |
86 | |
122 | |
87 | Exit any active loop or dispatch after C<$after> seconds or immediately if |
123 | The $flags argument can be one of the following: |
88 | C<$after> is missing or zero. |
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89 | |
124 | |
90 | =item EV::dispatch |
125 | 0 as above |
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126 | EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
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127 | EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
91 | |
128 | |
92 | Same as C<EV::loop 0>. |
129 | =item EV::unloop [$how] |
93 | |
130 | |
94 | =item EV::event $callback |
131 | When called with no arguments or an argument of EV::UNLOOP_ONE, makes the |
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132 | innermost call to EV::loop return. |
95 | |
133 | |
96 | Creates a new event watcher waiting for nothing, calling the given callback. |
134 | When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as |
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135 | fast as possible. |
97 | |
136 | |
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137 | =item $count = EV::loop_count |
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138 | |
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139 | Return the number of times the event loop has polled for new |
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140 | events. Sometiems useful as a generation counter. |
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141 | |
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142 | =item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) |
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143 | |
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144 | This function rolls together an I/O and a timer watcher for a single |
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145 | one-shot event without the need for managing a watcher object. |
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146 | |
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147 | If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events> |
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148 | must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ |
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149 | | EV::WRITE>, indicating the type of I/O event you want to wait for. If |
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150 | you do not want to wait for some I/O event, specify C<undef> for |
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151 | C<$fh_or_undef> and C<0> for C<$events>). |
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152 | |
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153 | If timeout is C<undef> or negative, then there will be no |
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154 | timeout. Otherwise a EV::timer with this value will be started. |
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155 | |
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156 | When an error occurs or either the timeout or I/O watcher triggers, then |
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157 | the callback will be called with the received event set (in general |
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158 | you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>, |
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159 | C<EV::WRITE> and C<EV::TIMEOUT>). |
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160 | |
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161 | EV::once doesn't return anything: the watchers stay active till either |
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162 | of them triggers, then they will be stopped and freed, and the callback |
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163 | invoked. |
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164 | |
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165 | =back |
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166 | |
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167 | =head2 WATCHER OBJECTS |
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168 | |
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169 | A watcher is an object that gets created to record your interest in some |
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170 | event. For instance, if you want to wait for STDIN to become readable, you |
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171 | would create an EV::io watcher for that: |
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172 | |
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173 | my $watcher = EV::io *STDIN, EV::READ, sub { |
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174 | my ($watcher, $revents) = @_; |
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175 | warn "yeah, STDIN should not be readable without blocking!\n" |
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176 | }; |
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177 | |
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178 | All watchers can be active (waiting for events) or inactive (paused). Only |
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179 | active watchers will have their callbacks invoked. All callbacks will be |
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180 | called with at least two arguments: the watcher and a bitmask of received |
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181 | events. |
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182 | |
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183 | Each watcher type has its associated bit in revents, so you can use the |
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184 | same callback for multiple watchers. The event mask is named after the |
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185 | type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
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186 | EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events |
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187 | (which can set both EV::READ and EV::WRITE bits), and EV::timer (which |
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188 | uses EV::TIMEOUT). |
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189 | |
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190 | In the rare case where one wants to create a watcher but not start it at |
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191 | the same time, each constructor has a variant with a trailing C<_ns> in |
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192 | its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. |
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193 | |
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194 | Please note that a watcher will automatically be stopped when the watcher |
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195 | object is destroyed, so you I<need> to keep the watcher objects returned by |
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196 | the constructors. |
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197 | |
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198 | Also, all methods changing some aspect of a watcher (->set, ->priority, |
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199 | ->fh and so on) automatically stop and start it again if it is active, |
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200 | which means pending events get lost. |
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201 | |
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202 | =head2 COMMON WATCHER METHODS |
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203 | |
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204 | This section lists methods common to all watchers. |
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205 | |
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206 | =over 4 |
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207 | |
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208 | =item $w->start |
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209 | |
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210 | Starts a watcher if it isn't active already. Does nothing to an already |
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211 | active watcher. By default, all watchers start out in the active state |
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212 | (see the description of the C<_ns> variants if you need stopped watchers). |
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213 | |
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214 | =item $w->stop |
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215 | |
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216 | Stop a watcher if it is active. Also clear any pending events (events that |
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217 | have been received but that didn't yet result in a callback invocation), |
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218 | regardless of whether the watcher was active or not. |
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219 | |
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220 | =item $bool = $w->is_active |
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221 | |
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222 | Returns true if the watcher is active, false otherwise. |
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223 | |
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224 | =item $current_data = $w->data |
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225 | |
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226 | =item $old_data = $w->data ($new_data) |
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227 | |
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228 | Queries a freely usable data scalar on the watcher and optionally changes |
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229 | it. This is a way to associate custom data with a watcher: |
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230 | |
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231 | my $w = EV::timer 60, 0, sub { |
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232 | warn $_[0]->data; |
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233 | }; |
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234 | $w->data ("print me!"); |
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235 | |
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236 | =item $current_cb = $w->cb |
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237 | |
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238 | =item $old_cb = $w->cb ($new_cb) |
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239 | |
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240 | Queries the callback on the watcher and optionally changes it. You can do |
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241 | this at any time without the watcher restarting. |
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242 | |
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243 | =item $current_priority = $w->priority |
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244 | |
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245 | =item $old_priority = $w->priority ($new_priority) |
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246 | |
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247 | Queries the priority on the watcher and optionally changes it. Pending |
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248 | watchers with higher priority will be invoked first. The valid range of |
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249 | priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default |
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250 | -2). If the priority is outside this range it will automatically be |
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251 | normalised to the nearest valid priority. |
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252 | |
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253 | The default priority of any newly-created watcher is 0. |
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254 | |
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255 | Note that the priority semantics have not yet been fleshed out and are |
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256 | subject to almost certain change. |
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257 | |
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258 | =item $w->trigger ($revents) |
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259 | |
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260 | Call the callback *now* with the given event mask. |
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261 | |
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262 | =item $previous_state = $w->keepalive ($bool) |
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263 | |
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264 | Normally, C<EV::loop> will return when there are no active watchers |
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265 | (which is a "deadlock" because no progress can be made anymore). This is |
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266 | convinient because it allows you to start your watchers (and your jobs), |
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267 | call C<EV::loop> once and when it returns you know that all your jobs are |
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268 | finished (or they forgot to register some watchers for their task :). |
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269 | |
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270 | Sometimes, however, this gets in your way, for example when you the module |
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271 | that calls C<EV::loop> (usually the main program) is not the same module |
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272 | as a long-living watcher (for example a DNS client module written by |
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273 | somebody else even). Then you might want any outstanding requests to be |
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274 | handled, but you would not want to keep C<EV::loop> from returning just |
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275 | because you happen to have this long-running UDP port watcher. |
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276 | |
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277 | In this case you can clear the keepalive status, which means that even |
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278 | though your watcher is active, it won't keep C<EV::loop> from returning. |
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279 | |
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280 | The initial value for keepalive is true (enabled), and you cna change it |
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281 | any time. |
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282 | |
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283 | Example: Register an I/O watcher for some UDP socket but do not keep the |
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284 | event loop from running just because of that watcher. |
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285 | |
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286 | my $udp_socket = ... |
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287 | my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; |
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288 | $udp_watcher->keepalive (0); |
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289 | |
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290 | =back |
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291 | |
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292 | |
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293 | =head2 WATCHER TYPES |
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294 | |
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295 | Each of the following subsections describes a single watcher type. |
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296 | |
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297 | =head3 I/O WATCHERS - is this file descriptor readable or writable? |
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298 | |
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299 | =over 4 |
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300 | |
98 | =item my $w = EV::io $fileno_or_fh, $eventmask, $callback |
301 | =item $w = EV::io $fileno_or_fh, $eventmask, $callback |
99 | |
302 | |
100 | =item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
303 | =item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
101 | |
304 | |
102 | As long as the returned watcher object is alive, call the C<$callback> |
305 | As long as the returned watcher object is alive, call the C<$callback> |
103 | when the events specified in C<$eventmask> happen. Initially, the timeout |
306 | when at least one of events specified in C<$eventmask> occurs. |
104 | is disabled. |
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105 | |
307 | |
106 | The C<io_ns> variant doesn't add/start the newly created watcher. |
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107 | |
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108 | Eventmask can be one or more of these constants ORed together: |
308 | The $eventmask can be one or more of these constants ORed together: |
109 | |
309 | |
110 | EV::READ wait until read() wouldn't block anymore |
310 | EV::READ wait until read() wouldn't block anymore |
111 | EV::WRITE wait until write() wouldn't block anymore |
311 | EV::WRITE wait until write() wouldn't block anymore |
112 | EV::PERSIST stay active after an event occured |
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113 | |
312 | |
114 | =item my $w = EV::timer $after, $repeat, $callback |
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115 | |
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116 | =item my $w = EV::timer_ns $after, $repeat, $callback |
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117 | |
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118 | Calls the callback after C<$after> seconds. If C<$repeat> is true, the |
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119 | timer will be restarted after the callback returns. This means that the |
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120 | callback would be called roughly every C<$after> seconds, prolonged by the |
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121 | time the callback takes. |
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122 | |
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123 | The C<timer_ns> variant doesn't add/start the newly created watcher. |
313 | The C<io_ns> variant doesn't start (activate) the newly created watcher. |
124 | |
314 | |
125 | =item my $w = EV::timer_abs $at, $interval, $callback |
315 | =item $w->set ($fileno_or_fh, $eventmask) |
126 | |
316 | |
127 | =item my $w = EV::timer_abs_ns $at, $interval, $callback |
317 | Reconfigures the watcher, see the constructor above for details. Can be |
128 | |
318 | called at any time. |
129 | Similar to EV::timer, but the time is given as an absolute point in time |
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130 | (C<$at>), plus an optional C<$interval>. |
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131 | |
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132 | If the C<$interval> is zero, then the callback will be called at the time |
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133 | C<$at> if that is in the future, or as soon as possible if its in the |
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134 | past. It will not automatically repeat. |
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135 | |
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136 | If the C<$interval> is nonzero, then the watcher will always be scheduled |
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137 | to time out at the next C<$at + integer * $interval> time. |
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138 | |
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139 | This can be used to schedule a callback to run at very regular intervals, |
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140 | as long as the processing time is less then the interval (otherwise |
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141 | obviously events will be skipped). |
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142 | |
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143 | The C<timer_abs_ns> variant doesn't add/start the newly created watcher. |
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144 | |
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145 | =item my $w = EV::signal $signum, $callback |
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146 | |
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147 | =item my $w = EV::signal_ns $signum, $callback |
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148 | |
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149 | Call the callback when signal $signum is received. |
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150 | |
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151 | The C<signal_ns> variant doesn't add/start the newly created watcher. |
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152 | |
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153 | =back |
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154 | |
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155 | =head1 THE EV::Event CLASS |
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156 | |
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157 | All EV functions creating an event watcher (designated by C<my $w => |
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158 | above) support the following methods on the returned watcher object: |
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159 | |
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160 | =over 4 |
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161 | |
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162 | =item $w->add ($timeout) |
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163 | |
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164 | Stops and (re-)starts the event watcher, setting the optional timeout to |
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165 | the given value, or clearing the timeout if none is given. |
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166 | |
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167 | =item $w->start |
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168 | |
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169 | Stops and (re-)starts the event watcher without touching the timeout. |
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170 | |
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171 | =item $w->del |
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172 | |
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173 | =item $w->stop |
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174 | |
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175 | Stop the event watcher if it was started. |
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176 | |
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177 | =item $current_callback = $w->cb |
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178 | |
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179 | =item $old_callback = $w->cb ($new_callback) |
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180 | |
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181 | Return the previously set callback and optionally set a new one. |
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182 | |
319 | |
183 | =item $current_fh = $w->fh |
320 | =item $current_fh = $w->fh |
184 | |
321 | |
185 | =item $old_fh = $w->fh ($new_fh) |
322 | =item $old_fh = $w->fh ($new_fh) |
186 | |
323 | |
… | |
… | |
190 | |
327 | |
191 | =item $old_eventmask = $w->events ($new_eventmask) |
328 | =item $old_eventmask = $w->events ($new_eventmask) |
192 | |
329 | |
193 | Returns the previously set event mask and optionally set a new one. |
330 | Returns the previously set event mask and optionally set a new one. |
194 | |
331 | |
|
|
332 | =back |
|
|
333 | |
|
|
334 | |
|
|
335 | =head3 TIMER WATCHERS - relative and optionally repeating timeouts |
|
|
336 | |
|
|
337 | =over 4 |
|
|
338 | |
|
|
339 | =item $w = EV::timer $after, $repeat, $callback |
|
|
340 | |
|
|
341 | =item $w = EV::timer_ns $after, $repeat, $callback |
|
|
342 | |
|
|
343 | Calls the callback after C<$after> seconds (which may be fractional). If |
|
|
344 | C<$repeat> is non-zero, the timer will be restarted (with the $repeat |
|
|
345 | value as $after) after the callback returns. |
|
|
346 | |
|
|
347 | This means that the callback would be called roughly after C<$after> |
|
|
348 | seconds, and then every C<$repeat> seconds. The timer does his best not |
|
|
349 | to drift, but it will not invoke the timer more often then once per event |
|
|
350 | loop iteration, and might drift in other cases. If that isn't acceptable, |
|
|
351 | look at EV::periodic, which can provide long-term stable timers. |
|
|
352 | |
|
|
353 | The timer is based on a monotonic clock, that is, if somebody is sitting |
|
|
354 | in front of the machine while the timer is running and changes the system |
|
|
355 | clock, the timer will nevertheless run (roughly) the same time. |
|
|
356 | |
|
|
357 | The C<timer_ns> variant doesn't start (activate) the newly created watcher. |
|
|
358 | |
195 | =item $w->timeout ($after, $repeat) |
359 | =item $w->set ($after, $repeat) |
196 | |
360 | |
197 | Resets the timeout (see C<EV::timer> for details). |
361 | Reconfigures the watcher, see the constructor above for details. Can be called at |
|
|
362 | any time. |
198 | |
363 | |
199 | =item $w->timeout_abs ($at, $interval) |
364 | =item $w->again |
200 | |
365 | |
201 | Resets the timeout (see C<EV::timer_abs> for details). |
366 | Similar to the C<start> method, but has special semantics for repeating timers: |
202 | |
367 | |
203 | =item $w->priority_set ($priority) |
368 | If the timer is active and non-repeating, it will be stopped. |
204 | |
369 | |
205 | Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI). |
370 | If the timer is active and repeating, reset the timeout to occur |
|
|
371 | C<$repeat> seconds after now. |
206 | |
372 | |
207 | =back |
373 | If the timer is inactive and repeating, start it using the repeat value. |
208 | |
374 | |
209 | =head1 BUGS |
375 | Otherwise do nothing. |
210 | |
376 | |
211 | Lots. Libevent itself isn't well tested and rather buggy, and this module |
377 | This behaviour is useful when you have a timeout for some IO |
212 | is quite new at the moment. |
378 | operation. You create a timer object with the same value for C<$after> and |
|
|
379 | C<$repeat>, and then, in the read/write watcher, run the C<again> method |
|
|
380 | on the timeout. |
213 | |
381 | |
214 | Please note that the epoll method is not, in general, reliable in |
382 | =back |
215 | programs that use fork (even if no libveent calls are being made in the |
383 | |
216 | forked process). Since this is such a common issue, this module will |
384 | |
217 | force the epoll method in EV to be off *unless* the global variable |
385 | =head3 PERIODIC WATCHERS - to cron or not to cron? |
218 | $EV::ENABLE_EPOLL is set to 1 *before* loading this module for the first |
386 | |
|
|
387 | =over 4 |
|
|
388 | |
|
|
389 | =item $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
|
|
390 | |
|
|
391 | =item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
|
|
392 | |
|
|
393 | Similar to EV::timer, but is not based on relative timeouts but on |
|
|
394 | absolute times. Apart from creating "simple" timers that trigger "at" the |
|
|
395 | specified time, it can also be used for non-drifting absolute timers and |
|
|
396 | more complex, cron-like, setups that are not adversely affected by time |
|
|
397 | jumps (i.e. when the system clock is changed by explicit date -s or other |
|
|
398 | means such as ntpd). It is also the most complex watcher type in EV. |
|
|
399 | |
|
|
400 | It has three distinct "modes": |
|
|
401 | |
|
|
402 | =over 4 |
|
|
403 | |
|
|
404 | =item * absolute timer ($interval = $reschedule_cb = 0) |
|
|
405 | |
|
|
406 | This time simply fires at the wallclock time C<$at> and doesn't repeat. It |
|
|
407 | will not adjust when a time jump occurs, that is, if it is to be run |
|
|
408 | at January 1st 2011 then it will run when the system time reaches or |
|
|
409 | surpasses this time. |
|
|
410 | |
|
|
411 | =item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) |
|
|
412 | |
|
|
413 | In this mode the watcher will always be scheduled to time out at the |
|
|
414 | next C<$at + N * $interval> time (for some integer N) and then repeat, |
|
|
415 | regardless of any time jumps. |
|
|
416 | |
|
|
417 | This can be used to create timers that do not drift with respect to system |
219 | time. |
418 | time: |
|
|
419 | |
|
|
420 | my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; |
|
|
421 | |
|
|
422 | That doesn't mean there will always be 3600 seconds in between triggers, |
|
|
423 | but only that the the clalback will be called when the system time shows a |
|
|
424 | full hour (UTC). |
|
|
425 | |
|
|
426 | Another way to think about it (for the mathematically inclined) is that |
|
|
427 | EV::periodic will try to run the callback in this mode at the next |
|
|
428 | possible time where C<$time = $at (mod $interval)>, regardless of any time |
|
|
429 | jumps. |
|
|
430 | |
|
|
431 | =item * manual reschedule mode ($reschedule_cb = coderef) |
|
|
432 | |
|
|
433 | In this mode $interval and $at are both being ignored. Instead, each |
|
|
434 | time the periodic watcher gets scheduled, the reschedule callback |
|
|
435 | ($reschedule_cb) will be called with the watcher as first, and the current |
|
|
436 | time as second argument. |
|
|
437 | |
|
|
438 | I<This callback MUST NOT stop or destroy this or any other periodic |
|
|
439 | watcher, ever>. If you need to stop it, return 1e30 and stop it |
|
|
440 | afterwards. |
|
|
441 | |
|
|
442 | It must return the next time to trigger, based on the passed time value |
|
|
443 | (that is, the lowest time value larger than to the second argument). It |
|
|
444 | will usually be called just before the callback will be triggered, but |
|
|
445 | might be called at other times, too. |
|
|
446 | |
|
|
447 | This can be used to create very complex timers, such as a timer that |
|
|
448 | triggers on each midnight, local time (actually 24 hours after the last |
|
|
449 | midnight, to keep the example simple. If you know a way to do it correctly |
|
|
450 | in about the same space (without requiring elaborate modules), drop me a |
|
|
451 | note :): |
|
|
452 | |
|
|
453 | my $daily = EV::periodic 0, 0, sub { |
|
|
454 | my ($w, $now) = @_; |
|
|
455 | |
|
|
456 | use Time::Local (); |
|
|
457 | my (undef, undef, undef, $d, $m, $y) = localtime $now; |
|
|
458 | 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y |
|
|
459 | }, sub { |
|
|
460 | print "it's midnight or likely shortly after, now\n"; |
|
|
461 | }; |
|
|
462 | |
|
|
463 | =back |
|
|
464 | |
|
|
465 | The C<periodic_ns> variant doesn't start (activate) the newly created watcher. |
|
|
466 | |
|
|
467 | =item $w->set ($at, $interval, $reschedule_cb) |
|
|
468 | |
|
|
469 | Reconfigures the watcher, see the constructor above for details. Can be called at |
|
|
470 | any time. |
|
|
471 | |
|
|
472 | =item $w->again |
|
|
473 | |
|
|
474 | Simply stops and starts the watcher again. |
|
|
475 | |
|
|
476 | =back |
|
|
477 | |
|
|
478 | |
|
|
479 | =head3 SIGNAL WATCHERS - signal me when a signal gets signalled! |
|
|
480 | |
|
|
481 | =over 4 |
|
|
482 | |
|
|
483 | =item $w = EV::signal $signal, $callback |
|
|
484 | |
|
|
485 | =item $w = EV::signal_ns $signal, $callback |
|
|
486 | |
|
|
487 | Call the callback when $signal is received (the signal can be specified by |
|
|
488 | number or by name, just as with C<kill> or C<%SIG>). |
|
|
489 | |
|
|
490 | EV will grab the signal for the process (the kernel only allows one |
|
|
491 | component to receive a signal at a time) when you start a signal watcher, |
|
|
492 | and removes it again when you stop it. Perl does the same when you |
|
|
493 | add/remove callbacks to C<%SIG>, so watch out. |
|
|
494 | |
|
|
495 | You can have as many signal watchers per signal as you want. |
|
|
496 | |
|
|
497 | The C<signal_ns> variant doesn't start (activate) the newly created watcher. |
|
|
498 | |
|
|
499 | =item $w->set ($signal) |
|
|
500 | |
|
|
501 | Reconfigures the watcher, see the constructor above for details. Can be |
|
|
502 | called at any time. |
|
|
503 | |
|
|
504 | =item $current_signum = $w->signal |
|
|
505 | |
|
|
506 | =item $old_signum = $w->signal ($new_signal) |
|
|
507 | |
|
|
508 | Returns the previously set signal (always as a number not name) and |
|
|
509 | optionally set a new one. |
|
|
510 | |
|
|
511 | =back |
|
|
512 | |
|
|
513 | |
|
|
514 | =head3 CHILD WATCHERS - watch out for process status changes |
|
|
515 | |
|
|
516 | =over 4 |
|
|
517 | |
|
|
518 | =item $w = EV::child $pid, $callback |
|
|
519 | |
|
|
520 | =item $w = EV::child_ns $pid, $callback |
|
|
521 | |
|
|
522 | Call the callback when a status change for pid C<$pid> (or any pid if |
|
|
523 | C<$pid> is 0) has been received. More precisely: when the process receives |
|
|
524 | a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all |
|
|
525 | changed/zombie children and call the callback. |
|
|
526 | |
|
|
527 | It is valid (and fully supported) to install a child watcher after a child |
|
|
528 | has exited but before the event loop has started its next iteration (for |
|
|
529 | example, first you C<fork>, then the new child process might exit, and |
|
|
530 | only then do you install a child watcher in the parent for the new pid). |
|
|
531 | |
|
|
532 | You can access both exit (or tracing) status and pid by using the |
|
|
533 | C<rstatus> and C<rpid> methods on the watcher object. |
|
|
534 | |
|
|
535 | You can have as many pid watchers per pid as you want, they will all be |
|
|
536 | called. |
|
|
537 | |
|
|
538 | The C<child_ns> variant doesn't start (activate) the newly created watcher. |
|
|
539 | |
|
|
540 | =item $w->set ($pid) |
|
|
541 | |
|
|
542 | Reconfigures the watcher, see the constructor above for details. Can be called at |
|
|
543 | any time. |
|
|
544 | |
|
|
545 | =item $current_pid = $w->pid |
|
|
546 | |
|
|
547 | =item $old_pid = $w->pid ($new_pid) |
|
|
548 | |
|
|
549 | Returns the previously set process id and optionally set a new one. |
|
|
550 | |
|
|
551 | =item $exit_status = $w->rstatus |
|
|
552 | |
|
|
553 | Return the exit/wait status (as returned by waitpid, see the waitpid entry |
|
|
554 | in perlfunc). |
|
|
555 | |
|
|
556 | =item $pid = $w->rpid |
|
|
557 | |
|
|
558 | Return the pid of the awaited child (useful when you have installed a |
|
|
559 | watcher for all pids). |
|
|
560 | |
|
|
561 | =back |
|
|
562 | |
|
|
563 | |
|
|
564 | =head3 STAT WATCHERS - did the file attributes just change? |
|
|
565 | |
|
|
566 | =over 4 |
|
|
567 | |
|
|
568 | =item $w = EV::stat $path, $interval, $callback |
|
|
569 | |
|
|
570 | =item $w = EV::stat_ns $path, $interval, $callback |
|
|
571 | |
|
|
572 | Call the callback when a file status change has been detected on |
|
|
573 | C<$path>. The C<$path> does not need to exist, changing from "path exists" |
|
|
574 | to "path does not exist" is a status change like any other. |
|
|
575 | |
|
|
576 | The C<$interval> is a recommended polling interval for systems where |
|
|
577 | OS-supported change notifications don't exist or are not supported. If |
|
|
578 | you use C<0> then an unspecified default is used (which is highly |
|
|
579 | recommended!), which is to be expected to be around five seconds usually. |
|
|
580 | |
|
|
581 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
582 | as even with OS-supported change notifications, this can be |
|
|
583 | resource-intensive. |
|
|
584 | |
|
|
585 | The C<stat_ns> variant doesn't start (activate) the newly created watcher. |
|
|
586 | |
|
|
587 | =item ... = $w->stat |
|
|
588 | |
|
|
589 | This call is very similar to the perl C<stat> built-in: It stats (using |
|
|
590 | C<lstat>) the path specified in the watcher and sets perls stat cache (as |
|
|
591 | well as EV's idea of the current stat values) to the values found. |
|
|
592 | |
|
|
593 | In scalar context, a boolean is return indicating success or failure of |
|
|
594 | the stat. In list context, the same 13-value list as with stat is returned |
|
|
595 | (except that the blksize and blocks fields are not reliable). |
|
|
596 | |
|
|
597 | In the case of an error, errno is set to C<ENOENT> (regardless of the |
|
|
598 | actual error value) and the C<nlink> value is forced to zero (if the stat |
|
|
599 | was successful then nlink is guaranteed to be non-zero). |
|
|
600 | |
|
|
601 | See also the next two entries for more info. |
|
|
602 | |
|
|
603 | =item ... = $w->attr |
|
|
604 | |
|
|
605 | Just like C<< $w->stat >>, but without the initial stat'ing: this returns |
|
|
606 | the values most recently detected by EV. See the next entry for more info. |
|
|
607 | |
|
|
608 | =item ... = $w->prev |
|
|
609 | |
|
|
610 | Just like C<< $w->stat >>, but without the initial stat'ing: this returns |
|
|
611 | the previous set of values, before the change. |
|
|
612 | |
|
|
613 | That is, when the watcher callback is invoked, C<< $w->prev >> will be set |
|
|
614 | to the values found I<before> a change was detected, while C<< $w->attr >> |
|
|
615 | returns the values found leading to the change detection. The difference (if any) |
|
|
616 | between C<prev> and C<attr> is what triggered the callback. |
|
|
617 | |
|
|
618 | If you did something to the filesystem object and do not want to trigger |
|
|
619 | yet another change, you can call C<stat> to update EV's idea of what the |
|
|
620 | current attributes are. |
|
|
621 | |
|
|
622 | =item $w->set ($path, $interval) |
|
|
623 | |
|
|
624 | Reconfigures the watcher, see the constructor above for details. Can be |
|
|
625 | called at any time. |
|
|
626 | |
|
|
627 | =item $current_path = $w->path |
|
|
628 | |
|
|
629 | =item $old_path = $w->path ($new_path) |
|
|
630 | |
|
|
631 | Returns the previously set path and optionally set a new one. |
|
|
632 | |
|
|
633 | =item $current_interval = $w->interval |
|
|
634 | |
|
|
635 | =item $old_interval = $w->interval ($new_interval) |
|
|
636 | |
|
|
637 | Returns the previously set interval and optionally set a new one. Can be |
|
|
638 | used to query the actual interval used. |
|
|
639 | |
|
|
640 | =back |
|
|
641 | |
|
|
642 | |
|
|
643 | =head3 IDLE WATCHERS - when you've got nothing better to do... |
|
|
644 | |
|
|
645 | =over 4 |
|
|
646 | |
|
|
647 | =item $w = EV::idle $callback |
|
|
648 | |
|
|
649 | =item $w = EV::idle_ns $callback |
|
|
650 | |
|
|
651 | Call the callback when there are no other pending watchers of the same or |
|
|
652 | higher priority (excluding check, prepare and other idle watchers of the |
|
|
653 | same or lower priority, of course). They are called idle watchers because |
|
|
654 | when the watcher is the highest priority pending event in the process, the |
|
|
655 | process is considered to be idle at that priority. |
|
|
656 | |
|
|
657 | If you want a watcher that is only ever called when I<no> other events are |
|
|
658 | outstanding you have to set the priority to C<EV::MINPRI>. |
|
|
659 | |
|
|
660 | The process will not block as long as any idle watchers are active, and |
|
|
661 | they will be called repeatedly until stopped. |
|
|
662 | |
|
|
663 | For example, if you have idle watchers at priority C<0> and C<1>, and |
|
|
664 | an I/O watcher at priority C<0>, then the idle watcher at priority C<1> |
|
|
665 | and the I/O watcher will always run when ready. Only when the idle watcher |
|
|
666 | at priority C<1> is stopped and the I/O watcher at priority C<0> is not |
|
|
667 | pending with the C<0>-priority idle watcher be invoked. |
|
|
668 | |
|
|
669 | The C<idle_ns> variant doesn't start (activate) the newly created watcher. |
|
|
670 | |
|
|
671 | =back |
|
|
672 | |
|
|
673 | |
|
|
674 | =head3 PREPARE WATCHERS - customise your event loop! |
|
|
675 | |
|
|
676 | =over 4 |
|
|
677 | |
|
|
678 | =item $w = EV::prepare $callback |
|
|
679 | |
|
|
680 | =item $w = EV::prepare_ns $callback |
|
|
681 | |
|
|
682 | Call the callback just before the process would block. You can still |
|
|
683 | create/modify any watchers at this point. |
|
|
684 | |
|
|
685 | See the EV::check watcher, below, for explanations and an example. |
|
|
686 | |
|
|
687 | The C<prepare_ns> variant doesn't start (activate) the newly created watcher. |
|
|
688 | |
|
|
689 | =back |
|
|
690 | |
|
|
691 | |
|
|
692 | =head3 CHECK WATCHERS - customise your event loop even more! |
|
|
693 | |
|
|
694 | =over 4 |
|
|
695 | |
|
|
696 | =item $w = EV::check $callback |
|
|
697 | |
|
|
698 | =item $w = EV::check_ns $callback |
|
|
699 | |
|
|
700 | Call the callback just after the process wakes up again (after it has |
|
|
701 | gathered events), but before any other callbacks have been invoked. |
|
|
702 | |
|
|
703 | This is used to integrate other event-based software into the EV |
|
|
704 | mainloop: You register a prepare callback and in there, you create io and |
|
|
705 | timer watchers as required by the other software. Here is a real-world |
|
|
706 | example of integrating Net::SNMP (with some details left out): |
|
|
707 | |
|
|
708 | our @snmp_watcher; |
|
|
709 | |
|
|
710 | our $snmp_prepare = EV::prepare sub { |
|
|
711 | # do nothing unless active |
|
|
712 | $dispatcher->{_event_queue_h} |
|
|
713 | or return; |
|
|
714 | |
|
|
715 | # make the dispatcher handle any outstanding stuff |
|
|
716 | ... not shown |
|
|
717 | |
|
|
718 | # create an I/O watcher for each and every socket |
|
|
719 | @snmp_watcher = ( |
|
|
720 | (map { EV::io $_, EV::READ, sub { } } |
|
|
721 | keys %{ $dispatcher->{_descriptors} }), |
|
|
722 | |
|
|
723 | EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] |
|
|
724 | ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0), |
|
|
725 | 0, sub { }, |
|
|
726 | ); |
|
|
727 | }; |
|
|
728 | |
|
|
729 | The callbacks are irrelevant (and are not even being called), the |
|
|
730 | only purpose of those watchers is to wake up the process as soon as |
|
|
731 | one of those events occurs (socket readable, or timer timed out). The |
|
|
732 | corresponding EV::check watcher will then clean up: |
|
|
733 | |
|
|
734 | our $snmp_check = EV::check sub { |
|
|
735 | # destroy all watchers |
|
|
736 | @snmp_watcher = (); |
|
|
737 | |
|
|
738 | # make the dispatcher handle any new stuff |
|
|
739 | ... not shown |
|
|
740 | }; |
|
|
741 | |
|
|
742 | The callbacks of the created watchers will not be called as the watchers |
|
|
743 | are destroyed before this cna happen (remember EV::check gets called |
|
|
744 | first). |
|
|
745 | |
|
|
746 | The C<check_ns> variant doesn't start (activate) the newly created watcher. |
|
|
747 | |
|
|
748 | =back |
|
|
749 | |
|
|
750 | |
|
|
751 | =head3 FORK WATCHERS - the audacity to resume the event loop after a fork |
|
|
752 | |
|
|
753 | Fork watchers are called when a C<fork ()> was detected. The invocation |
|
|
754 | is done before the event loop blocks next and before C<check> watchers |
|
|
755 | are being called, and only in the child after the fork. |
|
|
756 | |
|
|
757 | =over 4 |
|
|
758 | |
|
|
759 | =item $w = EV::fork $callback |
|
|
760 | |
|
|
761 | =item $w = EV::fork_ns $callback |
|
|
762 | |
|
|
763 | Call the callback before the event loop is resumed in the child process |
|
|
764 | after a fork. |
|
|
765 | |
|
|
766 | The C<fork_ns> variant doesn't start (activate) the newly created watcher. |
|
|
767 | |
|
|
768 | =back |
|
|
769 | |
|
|
770 | |
|
|
771 | =head1 PERL SIGNALS |
|
|
772 | |
|
|
773 | While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour |
|
|
774 | with EV is as the same as any other C library: Perl-signals will only be |
|
|
775 | handled when Perl runs, which means your signal handler might be invoked |
|
|
776 | only the next time an event callback is invoked. |
|
|
777 | |
|
|
778 | The solution is to use EV signal watchers (see C<EV::signal>), which will |
|
|
779 | ensure proper operations with regards to other event watchers. |
|
|
780 | |
|
|
781 | If you cannot do this for whatever reason, you can also force a watcher |
|
|
782 | to be called on every event loop iteration by installing a C<EV::check> |
|
|
783 | watcher: |
|
|
784 | |
|
|
785 | my $async_check = EV::check sub { }; |
|
|
786 | |
|
|
787 | This ensures that perl shortly gets into control for a short time, and |
|
|
788 | also ensures slower overall operation. |
|
|
789 | |
|
|
790 | =head1 THREADS |
|
|
791 | |
|
|
792 | Threads are not supported by this module in any way. Perl pseudo-threads |
|
|
793 | is evil stuff and must die. As soon as Perl gains real threads I will work |
|
|
794 | on thread support for it. |
|
|
795 | |
|
|
796 | =head1 FORK |
|
|
797 | |
|
|
798 | Most of the "improved" event delivering mechanisms of modern operating |
|
|
799 | systems have quite a few problems with fork(2) (to put it bluntly: it is |
|
|
800 | not supported and usually destructive). Libev makes it possible to work |
|
|
801 | around this by having a function that recreates the kernel state after |
|
|
802 | fork in the child. |
|
|
803 | |
|
|
804 | On non-win32 platforms, this module requires the pthread_atfork |
|
|
805 | functionality to do this automatically for you. This function is quite |
|
|
806 | buggy on most BSDs, though, so YMMV. The overhead for this is quite |
|
|
807 | negligible, because everything the function currently does is set a flag |
|
|
808 | that is checked only when the event loop gets used the next time, so when |
|
|
809 | you do fork but not use EV, the overhead is minimal. |
|
|
810 | |
|
|
811 | On win32, there is no notion of fork so all this doesn't apply, of course. |
220 | |
812 | |
221 | =cut |
813 | =cut |
222 | |
814 | |
223 | our $NPRI = 4; |
815 | our $DIED = sub { |
224 | our $BASE; |
816 | warn "EV: error in callback (ignoring): $@"; |
225 | our $ENABLE_EPOLL; |
817 | }; |
226 | |
818 | |
227 | { |
819 | default_loop |
228 | local $ENV{EVENT_NOEPOLL}; |
820 | or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; |
229 | $ENV{EVENT_NOEPOLL} = 1 unless $ENABLE_EPOLL; |
|
|
230 | $BASE = init; |
|
|
231 | } |
|
|
232 | |
|
|
233 | priority_init $NPRI; |
|
|
234 | |
|
|
235 | push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"]; |
|
|
236 | |
821 | |
237 | 1; |
822 | 1; |
238 | |
823 | |
239 | =head1 SEE ALSO |
824 | =head1 SEE ALSO |
240 | |
825 | |
241 | L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>. |
826 | L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as |
242 | L<EV::AnyEvent>. |
827 | event loop), L<Coro::EV> (efficient coroutines with EV). |
243 | |
828 | |
244 | =head1 AUTHOR |
829 | =head1 AUTHOR |
245 | |
830 | |
246 | Marc Lehmann <schmorp@schmorp.de> |
831 | Marc Lehmann <schmorp@schmorp.de> |
247 | http://home.schmorp.de/ |
832 | http://home.schmorp.de/ |