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2 | EV - perl interface to libev, a high performance full-featured event |
2 | EV - perl interface to libev, a high performance full-featured event |
3 | loop |
3 | loop |
4 | |
4 | |
5 | SYNOPSIS |
5 | SYNOPSIS |
6 | use EV; |
6 | use EV; |
7 | |
7 | |
8 | # TIMERS |
8 | # TIMERS |
9 | |
9 | |
10 | my $w = EV::timer 2, 0, sub { |
10 | my $w = EV::timer 2, 0, sub { |
11 | warn "is called after 2s"; |
11 | warn "is called after 2s"; |
12 | }; |
12 | }; |
13 | |
13 | |
14 | my $w = EV::timer 2, 1, sub { |
14 | my $w = EV::timer 2, 2, sub { |
15 | warn "is called roughly every 2s (repeat = 1)"; |
15 | warn "is called roughly every 2s (repeat = 2)"; |
16 | }; |
16 | }; |
17 | |
17 | |
18 | undef $w; # destroy event watcher again |
18 | undef $w; # destroy event watcher again |
19 | |
19 | |
20 | my $w = EV::periodic 0, 60, sub { |
20 | my $w = EV::periodic 0, 60, 0, sub { |
21 | warn "is called every minute, on the minute, exactly"; |
21 | warn "is called every minute, on the minute, exactly"; |
22 | }; |
22 | }; |
23 | |
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24 | # IO |
23 | |
25 | |
24 | # IO |
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25 | |
26 | my $w = EV::io *STDIN, EV::READ, sub { |
26 | my $w = EV::io *STDIN, EV::READ, sub { |
27 | my ($w, $revents) = @_; # all callbacks get the watcher object and event mask |
27 | my ($w, $revents) = @_; # all callbacks receive the watcher and event mask |
28 | warn "stdin is readable, you entered: ", <STDIN>; |
28 | warn "stdin is readable, you entered: ", <STDIN>; |
29 | }; |
29 | }; |
30 | |
30 | |
31 | # SIGNALS |
31 | # SIGNALS |
32 | |
32 | |
33 | my $w = EV::signal 'QUIT', sub { |
33 | my $w = EV::signal 'QUIT', sub { |
34 | warn "sigquit received\n"; |
34 | warn "sigquit received\n"; |
35 | }; |
35 | }; |
36 | |
36 | |
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37 | # CHILD/PID STATUS CHANGES |
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38 | |
37 | my $w = EV::signal 3, sub { |
39 | my $w = EV::child 666, 0, sub { |
38 | warn "sigquit received (this is GNU/Linux, right?)\n"; |
40 | my ($w, $revents) = @_; |
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41 | my $status = $w->rstatus; |
39 | }; |
42 | }; |
40 | |
43 | |
41 | # CHILD/PID STATUS CHANGES |
44 | # STAT CHANGES |
42 | |
45 | my $w = EV::stat "/etc/passwd", 10, sub { |
43 | my $w = EV::child 666, sub { |
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44 | my ($w, $revents, $status) = @_; |
46 | my ($w, $revents) = @_; |
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47 | warn $w->path, " has changed somehow.\n"; |
45 | }; |
48 | }; |
46 | |
49 | |
47 | # MAINLOOP |
50 | # MAINLOOP |
48 | EV::loop; # loop until EV::loop_done is called |
51 | EV::loop; # loop until EV::unloop is called or all watchers stop |
49 | EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
52 | EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled |
50 | EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
53 | EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block |
51 | |
54 | |
52 | DESCRIPTION |
55 | DESCRIPTION |
53 | This module provides an interface to libev |
56 | This module provides an interface to libev |
54 | (<http://software.schmorp.de/pkg/libev.html>). |
57 | (<http://software.schmorp.de/pkg/libev.html>). While the documentation |
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58 | below is comprehensive, one might also consult the documentation of |
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59 | libev itself (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) |
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60 | for more subtle details on watcher semantics or some discussion on the |
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61 | available backends, or how to force a specific backend with |
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62 | "LIBEV_FLAGS", or just about in any case because it has much more |
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63 | detailed information. |
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64 | |
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65 | This module is very fast and scalable. It is actually so fast that you |
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66 | can use it through the AnyEvent module, stay portable to other event |
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67 | loops (if you don't rely on any watcher types not available through it) |
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68 | and still be faster than with any other event loop currently supported |
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69 | in Perl. |
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70 | |
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71 | EVENT LOOPS |
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72 | EV supports multiple event loops: There is a single "default event loop" |
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73 | that can handle everything including signals and child watchers, and any |
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74 | number of "dynamic event loops" that can use different backends (with |
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75 | various limitations), but no child and signal watchers. |
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76 | |
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77 | You do not have to do anything to create the default event loop: When |
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78 | the module is loaded a suitable backend is selected on the premise of |
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79 | selecting a working backend (which for example rules out kqueue on most |
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80 | BSDs). Modules should, unless they have "special needs" always use the |
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81 | default loop as this is fastest (perl-wise), best supported by other |
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82 | modules (e.g. AnyEvent or Coro) and most portable event loop. |
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83 | |
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84 | For specific programs you can create additional event loops dynamically. |
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85 | |
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86 | $loop = new EV::loop [$flags] |
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87 | Create a new event loop as per the specified flags. Please refer to |
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88 | the "ev_loop_new ()" function description in the libev documentation |
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89 | (<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTI |
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90 | ONS>) for more info. |
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91 | |
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92 | The loop will automatically be destroyed when it is no longer |
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93 | referenced by any watcher and the loop object goes out of scope. |
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94 | |
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95 | Using "EV::FLAG_FORKCHECK" is recommended, as only the default event |
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96 | loop is protected by this module. |
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97 | |
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98 | $loop->loop_fork |
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99 | Must be called after a fork in the child, before entering or |
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100 | continuing the event loop. An alternative is to use |
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101 | "EV::FLAG_FORKCHECK" which calls this fucntion automatically, at |
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102 | some performance loss (refer to the libev documentation). |
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103 | |
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104 | $loop = EV::default_loop [$flags] |
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105 | Return the default loop (which is a singleton object). |
55 | |
106 | |
56 | BASIC INTERFACE |
107 | BASIC INTERFACE |
57 | $EV::DIED |
108 | $EV::DIED |
58 | Must contain a reference to a function that is called when a |
109 | Must contain a reference to a function that is called when a |
59 | callback throws an exception (with $@ containing thr error). The |
110 | callback throws an exception (with $@ containing the error). The |
60 | default prints an informative message and continues. |
111 | default prints an informative message and continues. |
61 | |
112 | |
62 | If this callback throws an exception it will be silently ignored. |
113 | If this callback throws an exception it will be silently ignored. |
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114 | |
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115 | $flags = EV::supported_backends |
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116 | $flags = EV::recommended_backends |
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117 | $flags = EV::embeddable_backends |
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118 | Returns the set (see "EV::BACKEND_*" flags) of backends supported by |
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119 | this instance of EV, the set of recommended backends (supposed to be |
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120 | good) for this platform and the set of embeddable backends (see |
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121 | EMBED WATCHERS). |
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122 | |
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123 | EV::sleep $seconds |
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124 | Block the process for the given number of (fractional) seconds. |
63 | |
125 | |
64 | $time = EV::time |
126 | $time = EV::time |
65 | Returns the current time in (fractional) seconds since the epoch. |
127 | Returns the current time in (fractional) seconds since the epoch. |
66 | |
128 | |
67 | $time = EV::now |
129 | $time = EV::now |
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130 | $time = $loop->now |
68 | Returns the time the last event loop iteration has been started. |
131 | Returns the time the last event loop iteration has been started. |
69 | This is the time that (relative) timers are based on, and refering |
132 | This is the time that (relative) timers are based on, and refering |
70 | to it is usually faster then calling EV::time. |
133 | to it is usually faster then calling EV::time. |
71 | |
134 | |
72 | $method = EV::ev_method |
135 | $backend = EV::backend |
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136 | $backend = $loop->backend |
73 | Returns an integer describing the backend used by libev |
137 | Returns an integer describing the backend used by libev |
74 | (EV::METHOD_SELECT or EV::METHOD_EPOLL). |
138 | (EV::METHOD_SELECT or EV::METHOD_EPOLL). |
75 | |
139 | |
76 | EV::loop [$flags] |
140 | EV::loop [$flags] |
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141 | $loop->loop ([$flags]) |
77 | Begin checking for events and calling callbacks. It returns when a |
142 | Begin checking for events and calling callbacks. It returns when a |
78 | callback calls EV::loop_done. |
143 | callback calls EV::unloop. |
79 | |
144 | |
80 | The $flags argument can be one of the following: |
145 | The $flags argument can be one of the following: |
81 | |
146 | |
82 | 0 as above |
147 | 0 as above |
83 | EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
148 | EV::LOOP_ONESHOT block at most once (wait, but do not loop) |
84 | EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
149 | EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) |
85 | |
150 | |
86 | EV::loop_done [$how] |
151 | EV::unloop [$how] |
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152 | $loop->unloop ([$how]) |
87 | When called with no arguments or an argument of 1, makes the |
153 | When called with no arguments or an argument of EV::UNLOOP_ONE, |
88 | innermost call to EV::loop return. |
154 | makes the innermost call to EV::loop return. |
89 | |
155 | |
90 | When called with an agrument of 2, all calls to EV::loop will return |
156 | When called with an argument of EV::UNLOOP_ALL, all calls to |
91 | as fast as possible. |
157 | EV::loop will return as fast as possible. |
92 | |
158 | |
93 | WATCHER |
159 | $count = EV::loop_count |
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160 | $count = $loop->loop_count |
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161 | Return the number of times the event loop has polled for new events. |
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162 | Sometiems useful as a generation counter. |
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163 | |
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164 | EV::once $fh_or_undef, $events, $timeout, $cb->($revents) |
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165 | $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) |
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166 | This function rolls together an I/O and a timer watcher for a single |
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167 | one-shot event without the need for managing a watcher object. |
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168 | |
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169 | If $fh_or_undef is a filehandle or file descriptor, then $events |
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170 | must be a bitset containing either "EV::READ", "EV::WRITE" or |
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171 | "EV::READ | EV::WRITE", indicating the type of I/O event you want to |
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172 | wait for. If you do not want to wait for some I/O event, specify |
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173 | "undef" for $fh_or_undef and 0 for $events). |
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174 | |
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175 | If timeout is "undef" or negative, then there will be no timeout. |
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176 | Otherwise a EV::timer with this value will be started. |
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177 | |
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178 | When an error occurs or either the timeout or I/O watcher triggers, |
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179 | then the callback will be called with the received event set (in |
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180 | general you can expect it to be a combination of "EV::ERROR", |
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181 | "EV::READ", "EV::WRITE" and "EV::TIMEOUT"). |
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182 | |
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183 | EV::once doesn't return anything: the watchers stay active till |
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184 | either of them triggers, then they will be stopped and freed, and |
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185 | the callback invoked. |
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186 | |
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187 | EV::feed_fd_event ($fd, $revents) |
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188 | $loop->feed_fd_event ($fd, $revents) |
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189 | Feed an event on a file descriptor into EV. EV will react to this |
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190 | call as if the readyness notifications specified by $revents (a |
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191 | combination of "EV::READ" and "EV::WRITE") happened on the file |
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192 | descriptor $fd. |
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193 | |
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194 | EV::feed_signal_event ($signal) |
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195 | Feed a signal event into EV. EV will react to this call as if the |
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196 | signal specified by $signal had occured. |
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197 | |
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198 | EV::set_io_collect_interval $time |
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199 | $loop->set_io_collect_interval ($time) |
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200 | EV::set_timeout_collect_interval $time |
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201 | $loop->set_timeout_collect_interval ($time) |
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202 | These advanced functions set the minimum block interval when polling |
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203 | for I/O events and the minimum wait interval for timer events. See |
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204 | the libev documentation at |
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205 | <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONT |
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206 | ROLLING_THE_EVENT_LOOP> for a more detailed discussion. |
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207 | |
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208 | WATCHER OBJECTS |
94 | A watcher is an object that gets created to record your interest in some |
209 | A watcher is an object that gets created to record your interest in some |
95 | event. For instance, if you want to wait for STDIN to become readable, |
210 | event. For instance, if you want to wait for STDIN to become readable, |
96 | you would create an EV::io watcher for that: |
211 | you would create an EV::io watcher for that: |
97 | |
212 | |
98 | my $watcher = EV::io *STDIN, EV::READ, sub { |
213 | my $watcher = EV::io *STDIN, EV::READ, sub { |
99 | my ($watcher, $revents) = @_; |
214 | my ($watcher, $revents) = @_; |
100 | warn "yeah, STDIN should not be readable without blocking!\n" |
215 | warn "yeah, STDIN should now be readable without blocking!\n" |
101 | }; |
216 | }; |
102 | |
217 | |
103 | All watchers can be active (waiting for events) or inactive (paused). |
218 | All watchers can be active (waiting for events) or inactive (paused). |
104 | Only active watchers will have their callbacks invoked. All callbacks |
219 | Only active watchers will have their callbacks invoked. All callbacks |
105 | will be called with at least two arguments: the watcher and a bitmask of |
220 | will be called with at least two arguments: the watcher and a bitmask of |
106 | received events. |
221 | received events. |
107 | |
222 | |
108 | Each watcher type has its associated bit in revents, so you can use the |
223 | Each watcher type has its associated bit in revents, so you can use the |
109 | same callback for multiple watchers. The event mask is named after the |
224 | same callback for multiple watchers. The event mask is named after the |
110 | type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
225 | type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, |
111 | EV::periodic sets EV::PERIODIC and so on, with the exception of IO |
226 | EV::periodic sets EV::PERIODIC and so on, with the exception of I/O |
112 | events (which can set both EV::READ and EV::WRITE bits), and EV::timer |
227 | events (which can set both EV::READ and EV::WRITE bits), and EV::timer |
113 | (which uses EV::TIMEOUT). |
228 | (which uses EV::TIMEOUT). |
114 | |
229 | |
115 | In the rare case where one wants to create a watcher but not start it at |
230 | In the rare case where one wants to create a watcher but not start it at |
116 | the same time, each constructor has a variant with a trailing "_ns" in |
231 | the same time, each constructor has a variant with a trailing "_ns" in |
117 | its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. |
232 | its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. |
118 | |
233 | |
119 | Please note that a watcher will automatically be stopped when the |
234 | Please note that a watcher will automatically be stopped when the |
120 | watcher object is returned, so you *need* to keep the watcher objects |
235 | watcher object is destroyed, so you *need* to keep the watcher objects |
121 | returned by the constructors. |
236 | returned by the constructors. |
122 | |
237 | |
123 | WATCHER TYPES |
238 | Also, all methods changing some aspect of a watcher (->set, ->priority, |
124 | Now lets move to the existing watcher types and asociated methods. |
239 | ->fh and so on) automatically stop and start it again if it is active, |
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240 | which means pending events get lost. |
125 | |
241 | |
126 | The following methods are available for all watchers. Then followes a |
242 | COMMON WATCHER METHODS |
127 | description of each watcher constructor (EV::io, EV::timer, |
243 | This section lists methods common to all watchers. |
128 | EV::periodic, EV::signal, EV::child, EV::idle, EV::prepare and |
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129 | EV::check), followed by any type-specific methods (if any). |
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130 | |
244 | |
131 | $w->start |
245 | $w->start |
132 | Starts a watcher if it isn't active already. Does nothing to an |
246 | Starts a watcher if it isn't active already. Does nothing to an |
133 | already active watcher. By default, all watchers start out in the |
247 | already active watcher. By default, all watchers start out in the |
134 | active state (see the description of the "_ns" variants if you need |
248 | active state (see the description of the "_ns" variants if you need |
135 | stopped watchers). |
249 | stopped watchers). |
136 | |
250 | |
137 | $w->stop |
251 | $w->stop |
138 | Stop a watcher if it is active. Also clear any pending events |
252 | Stop a watcher if it is active. Also clear any pending events |
139 | (events that have been received but that didn't yet result in a |
253 | (events that have been received but that didn't yet result in a |
140 | callback invocation), regardless of wether the watcher was active or |
254 | callback invocation), regardless of whether the watcher was active |
141 | not. |
255 | or not. |
142 | |
256 | |
143 | $bool = $w->is_active |
257 | $bool = $w->is_active |
144 | Returns true if the watcher is active, false otherwise. |
258 | Returns true if the watcher is active, false otherwise. |
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259 | |
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260 | $current_data = $w->data |
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261 | $old_data = $w->data ($new_data) |
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262 | Queries a freely usable data scalar on the watcher and optionally |
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263 | changes it. This is a way to associate custom data with a watcher: |
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264 | |
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265 | my $w = EV::timer 60, 0, sub { |
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266 | warn $_[0]->data; |
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267 | }; |
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268 | $w->data ("print me!"); |
145 | |
269 | |
146 | $current_cb = $w->cb |
270 | $current_cb = $w->cb |
147 | $old_cb = $w->cb ($new_cb) |
271 | $old_cb = $w->cb ($new_cb) |
148 | Queries the callback on the watcher and optionally changes it. You |
272 | Queries the callback on the watcher and optionally changes it. You |
149 | cna do this at any time. |
273 | can do this at any time without the watcher restarting. |
150 | |
274 | |
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275 | $current_priority = $w->priority |
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276 | $old_priority = $w->priority ($new_priority) |
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277 | Queries the priority on the watcher and optionally changes it. |
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278 | Pending watchers with higher priority will be invoked first. The |
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279 | valid range of priorities lies between EV::MAXPRI (default 2) and |
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280 | EV::MINPRI (default -2). If the priority is outside this range it |
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281 | will automatically be normalised to the nearest valid priority. |
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282 | |
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283 | The default priority of any newly-created watcher is 0. |
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284 | |
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285 | Note that the priority semantics have not yet been fleshed out and |
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286 | are subject to almost certain change. |
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287 | |
151 | $w->trigger ($revents) |
288 | $w->invoke ($revents) |
152 | Call the callback *now* with the given event mask. |
289 | Call the callback *now* with the given event mask. |
153 | |
290 | |
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291 | $w->feed_event ($revents) |
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292 | Feed some events on this watcher into EV. EV will react to this call |
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293 | as if the watcher had received the given $revents mask. |
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294 | |
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295 | $revents = $w->clear_pending |
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296 | If the watcher is pending, this function clears its pending status |
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297 | and returns its $revents bitset (as if its callback was invoked). If |
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298 | the watcher isn't pending it does nothing and returns 0. |
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299 | |
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300 | $previous_state = $w->keepalive ($bool) |
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301 | Normally, "EV::loop" will return when there are no active watchers |
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302 | (which is a "deadlock" because no progress can be made anymore). |
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303 | This is convinient because it allows you to start your watchers (and |
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304 | your jobs), call "EV::loop" once and when it returns you know that |
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305 | all your jobs are finished (or they forgot to register some watchers |
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306 | for their task :). |
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307 | |
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308 | Sometimes, however, this gets in your way, for example when the |
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309 | module that calls "EV::loop" (usually the main program) is not the |
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310 | same module as a long-living watcher (for example a DNS client |
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311 | module written by somebody else even). Then you might want any |
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312 | outstanding requests to be handled, but you would not want to keep |
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313 | "EV::loop" from returning just because you happen to have this |
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314 | long-running UDP port watcher. |
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315 | |
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316 | In this case you can clear the keepalive status, which means that |
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317 | even though your watcher is active, it won't keep "EV::loop" from |
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318 | returning. |
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319 | |
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320 | The initial value for keepalive is true (enabled), and you cna |
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321 | change it any time. |
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322 | |
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323 | Example: Register an I/O watcher for some UDP socket but do not keep |
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324 | the event loop from running just because of that watcher. |
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325 | |
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326 | my $udp_socket = ... |
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327 | my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; |
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328 | $1000udp_watcher->keepalive (0); |
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329 | |
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330 | $loop = $w->loop |
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331 | Return the loop that this watcher is attached to. |
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332 | |
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333 | WATCHER TYPES |
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334 | Each of the following subsections describes a single watcher type. |
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335 | |
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336 | I/O WATCHERS - is this file descriptor readable or writable? |
154 | $w = EV::io $fileno_or_fh, $eventmask, $callback |
337 | $w = EV::io $fileno_or_fh, $eventmask, $callback |
155 | $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
338 | $w = EV::io_ns $fileno_or_fh, $eventmask, $callback |
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339 | $w = $loop->io ($fileno_or_fh, $eventmask, $callback) |
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340 | $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback) |
156 | As long as the returned watcher object is alive, call the $callback |
341 | As long as the returned watcher object is alive, call the $callback |
157 | when the events specified in $eventmask. |
342 | when at least one of events specified in $eventmask occurs. |
158 | |
343 | |
159 | The $eventmask can be one or more of these constants ORed together: |
344 | The $eventmask can be one or more of these constants ORed together: |
160 | |
345 | |
161 | EV::READ wait until read() wouldn't block anymore |
346 | EV::READ wait until read() wouldn't block anymore |
162 | EV::WRITE wait until write() wouldn't block anymore |
347 | EV::WRITE wait until write() wouldn't block anymore |
… | |
… | |
174 | |
359 | |
175 | $current_eventmask = $w->events |
360 | $current_eventmask = $w->events |
176 | $old_eventmask = $w->events ($new_eventmask) |
361 | $old_eventmask = $w->events ($new_eventmask) |
177 | Returns the previously set event mask and optionally set a new one. |
362 | Returns the previously set event mask and optionally set a new one. |
178 | |
363 | |
|
|
364 | TIMER WATCHERS - relative and optionally repeating timeouts |
179 | $w = EV::timer $after, $repeat, $callback |
365 | $w = EV::timer $after, $repeat, $callback |
180 | $w = EV::timer_ns $after, $repeat, $callback |
366 | $w = EV::timer_ns $after, $repeat, $callback |
181 | Calls the callback after $after seconds. If $repeat is non-zero, the |
367 | $w = $loop->timer ($after, $repeat, $callback) |
182 | timer will be restarted (with the $repeat value as $after) after the |
368 | $w = $loop->timer_ns ($after, $repeat, $callback) |
183 | callback returns. |
369 | Calls the callback after $after seconds (which may be fractional). |
|
|
370 | If $repeat is non-zero, the timer will be restarted (with the |
|
|
371 | $repeat value as $after) after the callback returns. |
184 | |
372 | |
185 | This means that the callback would be called roughly after $after |
373 | This means that the callback would be called roughly after $after |
186 | seconds, and then every $repeat seconds. "Roughly" because the time |
374 | seconds, and then every $repeat seconds. The timer does his best not |
187 | of callback processing is not taken into account, so the timer will |
375 | to drift, but it will not invoke the timer more often then once per |
188 | slowly drift. If that isn't acceptable, look at EV::periodic. |
376 | event loop iteration, and might drift in other cases. If that isn't |
|
|
377 | acceptable, look at EV::periodic, which can provide long-term stable |
|
|
378 | timers. |
189 | |
379 | |
190 | The timer is based on a monotonic clock, that is if somebody is |
380 | The timer is based on a monotonic clock, that is, if somebody is |
191 | sitting in front of the machine while the timer is running and |
381 | sitting in front of the machine while the timer is running and |
192 | changes the system clock, the timer will nevertheless run (roughly) |
382 | changes the system clock, the timer will nevertheless run (roughly) |
193 | the same time. |
383 | the same time. |
194 | |
384 | |
195 | The "timer_ns" variant doesn't start (activate) the newly created |
385 | The "timer_ns" variant doesn't start (activate) the newly created |
196 | watcher. |
386 | watcher. |
197 | |
387 | |
198 | $w->set ($after, $repeat) |
388 | $w->set ($after, $repeat) |
199 | Reconfigures the watcher, see the constructor above for details. Can |
389 | Reconfigures the watcher, see the constructor above for details. Can |
200 | be at any time. |
390 | be called at any time. |
201 | |
391 | |
202 | $w->again |
392 | $w->again |
203 | Similar to the "start" method, but has special semantics for |
393 | Similar to the "start" method, but has special semantics for |
204 | repeating timers: |
394 | repeating timers: |
205 | |
395 | |
|
|
396 | If the timer is active and non-repeating, it will be stopped. |
|
|
397 | |
206 | If the timer is active and repeating, reset the timeout to occur |
398 | If the timer is active and repeating, reset the timeout to occur |
207 | $repeat seconds after now. |
399 | $repeat seconds after now. |
208 | |
400 | |
209 | If the timer is active and non-repeating, it will be stopped. |
|
|
210 | |
|
|
211 | If the timer is in active and repeating, start it. |
401 | If the timer is inactive and repeating, start it using the repeat |
|
|
402 | value. |
212 | |
403 | |
213 | Otherwise do nothing. |
404 | Otherwise do nothing. |
214 | |
405 | |
215 | This behaviour is useful when you have a timeout for some IO |
406 | This behaviour is useful when you have a timeout for some IO |
216 | operation. You create a timer object with the same value for $after |
407 | operation. You create a timer object with the same value for $after |
217 | and $repeat, and then, in the read/write watcher, run the "again" |
408 | and $repeat, and then, in the read/write watcher, run the "again" |
218 | method on the timeout. |
409 | method on the timeout. |
219 | |
410 | |
|
|
411 | PERIODIC WATCHERS - to cron or not to cron? |
220 | $w = EV::periodic $at, $interval, $callback |
412 | $w = EV::periodic $at, $interval, $reschedule_cb, $callback |
221 | $w = EV::periodic_ns $at, $interval, $callback |
413 | $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback |
222 | Similar to EV::timer, but the time is given as an absolute point in |
414 | $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback) |
223 | time ($at), plus an optional $interval. |
415 | $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback) |
|
|
416 | Similar to EV::timer, but is not based on relative timeouts but on |
|
|
417 | absolute times. Apart from creating "simple" timers that trigger |
|
|
418 | "at" the specified time, it can also be used for non-drifting |
|
|
419 | absolute timers and more complex, cron-like, setups that are not |
|
|
420 | adversely affected by time jumps (i.e. when the system clock is |
|
|
421 | changed by explicit date -s or other means such as ntpd). It is also |
|
|
422 | the most complex watcher type in EV. |
224 | |
423 | |
225 | If the $interval is zero, then the callback will be called at the |
424 | It has three distinct "modes": |
226 | time $at if that is in the future, or as soon as possible if it is |
|
|
227 | in the past. It will not automatically repeat. |
|
|
228 | |
425 | |
229 | If the $interval is nonzero, then the watcher will always be |
426 | * absolute timer ($interval = $reschedule_cb = 0) |
230 | scheduled to time out at the next "$at + N * $interval" time. |
|
|
231 | |
427 | |
232 | This can be used to schedule a callback to run at very regular |
428 | This time simply fires at the wallclock time $at and doesn't |
233 | intervals, as long as the processing time is less then the interval |
429 | repeat. It will not adjust when a time jump occurs, that is, if |
234 | (otherwise obviously events will be skipped). |
430 | it is to be run at January 1st 2011 then it will run when the |
|
|
431 | system time reaches or surpasses this time. |
235 | |
432 | |
|
|
433 | * repeating interval timer ($interval > 0, $reschedule_cb = 0) |
|
|
434 | |
|
|
435 | In this mode the watcher will always be scheduled to time out at |
|
|
436 | the next "$at + N * $interval" time (for some integer N) and |
|
|
437 | then repeat, regardless of any time jumps. |
|
|
438 | |
|
|
439 | This can be used to create timers that do not drift with respect |
|
|
440 | to system time: |
|
|
441 | |
|
|
442 | my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" }; |
|
|
443 | |
|
|
444 | That doesn't mean there will always be 3600 seconds in between |
|
|
445 | triggers, but only that the the clalback will be called when the |
|
|
446 | system time shows a full hour (UTC). |
|
|
447 | |
236 | Another way to think about it (for the mathematically inclined) is |
448 | Another way to think about it (for the mathematically inclined) |
237 | that EV::periodic will try to run the callback at the next possible |
449 | is that EV::periodic will try to run the callback in this mode |
238 | time where "$time = $at (mod $interval)", regardless of any time |
450 | at the next possible time where "$time = $at (mod $interval)", |
239 | jumps. |
451 | regardless of any time jumps. |
240 | |
452 | |
241 | This periodic timer is based on "wallclock time", that is, if the |
453 | * manual reschedule mode ($reschedule_cb = coderef) |
242 | clock changes ("ntp", "date -s" etc.), then the timer will |
454 | |
243 | nevertheless run at the specified time. This means it will never |
455 | In this mode $interval and $at are both being ignored. Instead, |
244 | drift (it might jitter, but it will not drift). |
456 | each time the periodic watcher gets scheduled, the reschedule |
|
|
457 | callback ($reschedule_cb) will be called with the watcher as |
|
|
458 | first, and the current time as second argument. |
|
|
459 | |
|
|
460 | *This callback MUST NOT stop or destroy this or any other |
|
|
461 | periodic watcher, ever, and MUST NOT call any event loop |
|
|
462 | functions or methods*. If you need to stop it, return 1e30 and |
|
|
463 | stop it afterwards. You may create and start a "EV::prepare" |
|
|
464 | watcher for this task. |
|
|
465 | |
|
|
466 | It must return the next time to trigger, based on the passed |
|
|
467 | time value (that is, the lowest time value larger than or equal |
|
|
468 | to to the second argument). It will usually be called just |
|
|
469 | before the callback will be triggered, but might be called at |
|
|
470 | other times, too. |
|
|
471 | |
|
|
472 | This can be used to create very complex timers, such as a timer |
|
|
473 | that triggers on each midnight, local time (actually 24 hours |
|
|
474 | after the last midnight, to keep the example simple. If you know |
|
|
475 | a way to do it correctly in about the same space (without |
|
|
476 | requiring elaborate modules), drop me a note :): |
|
|
477 | |
|
|
478 | my $daily = EV::periodic 0, 0, sub { |
|
|
479 | my ($w, $now) = @_; |
|
|
480 | |
|
|
481 | use Time::Local (); |
|
|
482 | my (undef, undef, undef, $d, $m, $y) = localtime $now; |
|
|
483 | 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y |
|
|
484 | }, sub { |
|
|
485 | print "it's midnight or likely shortly after, now\n"; |
|
|
486 | }; |
245 | |
487 | |
246 | The "periodic_ns" variant doesn't start (activate) the newly created |
488 | The "periodic_ns" variant doesn't start (activate) the newly created |
247 | watcher. |
489 | watcher. |
248 | |
490 | |
249 | $w->set ($at, $interval) |
491 | $w->set ($at, $interval, $reschedule_cb) |
250 | Reconfigures the watcher, see the constructor above for details. Can |
492 | Reconfigures the watcher, see the constructor above for details. Can |
251 | be at any time. |
493 | be called at any time. |
252 | |
494 | |
|
|
495 | $w->again |
|
|
496 | Simply stops and starts the watcher again. |
|
|
497 | |
|
|
498 | $time = $w->at |
|
|
499 | Return the time that the watcher is expected to trigger next. |
|
|
500 | |
|
|
501 | SIGNAL WATCHERS - signal me when a signal gets signalled! |
253 | $w = EV::signal $signal, $callback |
502 | $w = EV::signal $signal, $callback |
254 | $w = EV::signal_ns $signal, $callback |
503 | $w = EV::signal_ns $signal, $callback |
255 | Call the callback when $signal is received (the signal can be |
504 | Call the callback when $signal is received (the signal can be |
256 | specified by number or by name, just as with kill or %SIG). |
505 | specified by number or by name, just as with "kill" or %SIG). |
257 | |
506 | |
258 | EV will grab the signal for the process (the kernel only allows one |
507 | EV will grab the signal for the process (the kernel only allows one |
259 | component to receive a signal at a time) when you start a signal |
508 | component to receive a signal at a time) when you start a signal |
260 | watcher, and removes it again when you stop it. Perl does the same |
509 | watcher, and removes it again when you stop it. Perl does the same |
261 | when you add/remove callbacks to %SIG, so watch out. |
510 | when you add/remove callbacks to %SIG, so watch out. |
… | |
… | |
265 | The "signal_ns" variant doesn't start (activate) the newly created |
514 | The "signal_ns" variant doesn't start (activate) the newly created |
266 | watcher. |
515 | watcher. |
267 | |
516 | |
268 | $w->set ($signal) |
517 | $w->set ($signal) |
269 | Reconfigures the watcher, see the constructor above for details. Can |
518 | Reconfigures the watcher, see the constructor above for details. Can |
270 | be at any time. |
519 | be called at any time. |
271 | |
520 | |
|
|
521 | $current_signum = $w->signal |
|
|
522 | $old_signum = $w->signal ($new_signal) |
|
|
523 | Returns the previously set signal (always as a number not name) and |
|
|
524 | optionally set a new one. |
|
|
525 | |
|
|
526 | CHILD WATCHERS - watch out for process status changes |
272 | $w = EV::child $pid, $callback |
527 | $w = EV::child $pid, $trace, $callback |
273 | $w = EV::child_ns $pid, $callback |
528 | $w = EV::child_ns $pid, $trace, $callback |
|
|
529 | $w = $loop->child ($pid, $trace, $callback) |
|
|
530 | $w = $loop->child_ns ($pid, $trace, $callback) |
274 | Call the callback when a status change for pid $pid (or any pid if |
531 | Call the callback when a status change for pid $pid (or any pid if |
275 | $pid is 0) has been received. More precisely: when the process |
532 | $pid is 0) has been received (a status change happens when the |
|
|
533 | process terminates or is killed, or, when trace is true, |
|
|
534 | additionally when it is stopped or continued). More precisely: when |
276 | receives a SIGCHLD, EV will fetch the outstanding exit/wait status |
535 | the process receives a "SIGCHLD", EV will fetch the outstanding |
277 | for all changed/zombie children and call the callback. |
536 | exit/wait status for all changed/zombie children and call the |
|
|
537 | callback. |
278 | |
538 | |
279 | Unlike all other callbacks, this callback will be called with an |
539 | It is valid (and fully supported) to install a child watcher after a |
280 | additional third argument which is the exit status. See the |
540 | child has exited but before the event loop has started its next |
281 | "waitpid" function for details. |
541 | iteration (for example, first you "fork", then the new child process |
|
|
542 | might exit, and only then do you install a child watcher in the |
|
|
543 | parent for the new pid). |
282 | |
544 | |
|
|
545 | You can access both exit (or tracing) status and pid by using the |
|
|
546 | "rstatus" and "rpid" methods on the watcher object. |
|
|
547 | |
283 | You can have as many pid watchers per pid as you want. |
548 | You can have as many pid watchers per pid as you want, they will all |
|
|
549 | be called. |
284 | |
550 | |
285 | The "child_ns" variant doesn't start (activate) the newly created |
551 | The "child_ns" variant doesn't start (activate) the newly created |
286 | watcher. |
552 | watcher. |
287 | |
553 | |
288 | $w->set ($pid) |
554 | $w->set ($pid, $trace) |
289 | Reconfigures the watcher, see the constructor above for details. Can |
555 | Reconfigures the watcher, see the constructor above for details. Can |
290 | be at any time. |
556 | be called at any time. |
291 | |
557 | |
|
|
558 | $current_pid = $w->pid |
|
|
559 | Returns the previously set process id and optionally set a new one. |
|
|
560 | |
|
|
561 | $exit_status = $w->rstatus |
|
|
562 | Return the exit/wait status (as returned by waitpid, see the waitpid |
|
|
563 | entry in perlfunc). |
|
|
564 | |
|
|
565 | $pid = $w->rpid |
|
|
566 | Return the pid of the awaited child (useful when you have installed |
|
|
567 | a watcher for all pids). |
|
|
568 | |
|
|
569 | STAT WATCHERS - did the file attributes just change? |
|
|
570 | $w = EV::stat $path, $interval, $callback |
|
|
571 | $w = EV::stat_ns $path, $interval, $callback |
|
|
572 | $w = $loop->stat ($path, $interval, $callback) |
|
|
573 | $w = $loop->stat_ns ($path, $interval, $callback) |
|
|
574 | Call the callback when a file status change has been detected on |
|
|
575 | $path. The $path does not need to exist, changing from "path exists" |
|
|
576 | to "path does not exist" is a status change like any other. |
|
|
577 | |
|
|
578 | The $interval is a recommended polling interval for systems where |
|
|
579 | OS-supported change notifications don't exist or are not supported. |
|
|
580 | If you use 0 then an unspecified default is used (which is highly |
|
|
581 | recommended!), which is to be expected to be around five seconds |
|
|
582 | usually. |
|
|
583 | |
|
|
584 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
585 | as even with OS-supported change notifications, this can be |
|
|
586 | resource-intensive. |
|
|
587 | |
|
|
588 | The "stat_ns" variant doesn't start (activate) the newly created |
|
|
589 | watcher. |
|
|
590 | |
|
|
591 | ... = $w->stat |
|
|
592 | This call is very similar to the perl "stat" built-in: It stats |
|
|
593 | (using "lstat") the path specified in the watcher and sets perls |
|
|
594 | stat cache (as well as EV's idea of the current stat values) to the |
|
|
595 | values found. |
|
|
596 | |
|
|
597 | In scalar context, a boolean is return indicating success or failure |
|
|
598 | of the stat. In list context, the same 13-value list as with stat is |
|
|
599 | returned (except that the blksize and blocks fields are not |
|
|
600 | reliable). |
|
|
601 | |
|
|
602 | In the case of an error, errno is set to "ENOENT" (regardless of the |
|
|
603 | actual error value) and the "nlink" value is forced to zero (if the |
|
|
604 | stat was successful then nlink is guaranteed to be non-zero). |
|
|
605 | |
|
|
606 | See also the next two entries for more info. |
|
|
607 | |
|
|
608 | ... = $w->attr |
|
|
609 | Just like "$w->stat", but without the initial stat'ing: this returns |
|
|
610 | the values most recently detected by EV. See the next entry for more |
|
|
611 | info. |
|
|
612 | |
|
|
613 | ... = $w->prev |
|
|
614 | Just like "$w->stat", but without the initial stat'ing: this returns |
|
|
615 | the previous set of values, before the change. |
|
|
616 | |
|
|
617 | That is, when the watcher callback is invoked, "$w->prev" will be |
|
|
618 | set to the values found *before* a change was detected, while |
|
|
619 | "$w->attr" returns the values found leading to the change detection. |
|
|
620 | The difference (if any) between "prev" and "attr" is what triggered |
|
|
621 | the callback. |
|
|
622 | |
|
|
623 | If you did something to the filesystem object and do not want to |
|
|
624 | trigger yet another change, you can call "stat" to update EV's idea |
|
|
625 | of what the current attributes are. |
|
|
626 | |
|
|
627 | $w->set ($path, $interval) |
|
|
628 | Reconfigures the watcher, see the constructor above for details. Can |
|
|
629 | be called at any time. |
|
|
630 | |
|
|
631 | $current_path = $w->path |
|
|
632 | $old_path = $w->path ($new_path) |
|
|
633 | Returns the previously set path and optionally set a new one. |
|
|
634 | |
|
|
635 | $current_interval = $w->interval |
|
|
636 | $old_interval = $w->interval ($new_interval) |
|
|
637 | Returns the previously set interval and optionally set a new one. |
|
|
638 | Can be used to query the actual interval used. |
|
|
639 | |
|
|
640 | IDLE WATCHERS - when you've got nothing better to do... |
292 | $w = EV::idle $callback |
641 | $w = EV::idle $callback |
293 | $w = EV::idle_ns $callback |
642 | $w = EV::idle_ns $callback |
|
|
643 | $w = $loop->idle ($callback) |
|
|
644 | $w = $loop->idle_ns ($callback) |
294 | Call the callback when there are no pending io, timer/periodic, |
645 | Call the callback when there are no other pending watchers of the |
295 | signal or child events, i.e. when the process is idle. |
646 | same or higher priority (excluding check, prepare and other idle |
|
|
647 | watchers of the same or lower priority, of course). They are called |
|
|
648 | idle watchers because when the watcher is the highest priority |
|
|
649 | pending event in the process, the process is considered to be idle |
|
|
650 | at that priority. |
|
|
651 | |
|
|
652 | If you want a watcher that is only ever called when *no* other |
|
|
653 | events are outstanding you have to set the priority to "EV::MINPRI". |
296 | |
654 | |
297 | The process will not block as long as any idle watchers are active, |
655 | The process will not block as long as any idle watchers are active, |
298 | and they will be called repeatedly until stopped. |
656 | and they will be called repeatedly until stopped. |
299 | |
657 | |
|
|
658 | For example, if you have idle watchers at priority 0 and 1, and an |
|
|
659 | I/O watcher at priority 0, then the idle watcher at priority 1 and |
|
|
660 | the I/O watcher will always run when ready. Only when the idle |
|
|
661 | watcher at priority 1 is stopped and the I/O watcher at priority 0 |
|
|
662 | is not pending with the 0-priority idle watcher be invoked. |
|
|
663 | |
300 | The "idle_ns" variant doesn't start (activate) the newly created |
664 | The "idle_ns" variant doesn't start (activate) the newly created |
301 | watcher. |
665 | watcher. |
302 | |
666 | |
|
|
667 | PREPARE WATCHERS - customise your event loop! |
303 | $w = EV::prepare $callback |
668 | $w = EV::prepare $callback |
304 | $w = EV::prepare_ns $callback |
669 | $w = EV::prepare_ns $callback |
|
|
670 | $w = $loop->prepare ($callback) |
|
|
671 | $w = $loop->prepare_ns ($callback) |
305 | Call the callback just before the process would block. You can still |
672 | Call the callback just before the process would block. You can still |
306 | create/modify any watchers at this point. |
673 | create/modify any watchers at this point. |
307 | |
674 | |
308 | See the EV::check watcher, below, for explanations and an example. |
675 | See the EV::check watcher, below, for explanations and an example. |
309 | |
676 | |
310 | The "prepare_ns" variant doesn't start (activate) the newly created |
677 | The "prepare_ns" variant doesn't start (activate) the newly created |
311 | watcher. |
678 | watcher. |
312 | |
679 | |
|
|
680 | CHECK WATCHERS - customise your event loop even more! |
313 | $w = EV::check $callback |
681 | $w = EV::check $callback |
314 | $w = EV::check_ns $callback |
682 | $w = EV::check_ns $callback |
|
|
683 | $w = $loop->check ($callback) |
|
|
684 | $w = $loop->check_ns ($callback) |
315 | Call the callback just after the process wakes up again (after it |
685 | Call the callback just after the process wakes up again (after it |
316 | has gathered events), but before any other callbacks have been |
686 | has gathered events), but before any other callbacks have been |
317 | invoked. |
687 | invoked. |
318 | |
688 | |
319 | This is used to integrate other event-based software into the EV |
689 | This is used to integrate other event-based software into the EV |
… | |
… | |
328 | # do nothing unless active |
698 | # do nothing unless active |
329 | $dispatcher->{_event_queue_h} |
699 | $dispatcher->{_event_queue_h} |
330 | or return; |
700 | or return; |
331 | |
701 | |
332 | # make the dispatcher handle any outstanding stuff |
702 | # make the dispatcher handle any outstanding stuff |
|
|
703 | ... not shown |
333 | |
704 | |
334 | # create an IO watcher for each and every socket |
705 | # create an I/O watcher for each and every socket |
335 | @snmp_watcher = ( |
706 | @snmp_watcher = ( |
336 | (map { EV::io $_, EV::READ, sub { } } |
707 | (map { EV::io $_, EV::READ, sub { } } |
337 | keys %{ $dispatcher->{_descriptors} }), |
708 | keys %{ $dispatcher->{_descriptors} }), |
|
|
709 | |
|
|
710 | EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] |
|
|
711 | ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0), |
|
|
712 | 0, sub { }, |
338 | ); |
713 | ); |
339 | |
|
|
340 | # if there are any timeouts, also create a timer |
|
|
341 | push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { } |
|
|
342 | if $event->[Net::SNMP::Dispatcher::_ACTIVE]; |
|
|
343 | }; |
714 | }; |
344 | |
715 | |
345 | The callbacks are irrelevant, the only purpose of those watchers is |
716 | The callbacks are irrelevant (and are not even being called), the |
346 | to wake up the process as soon as one of those events occurs (socket |
717 | only purpose of those watchers is to wake up the process as soon as |
347 | readable, or timer timed out). The corresponding EV::check watcher |
718 | one of those events occurs (socket readable, or timer timed out). |
348 | will then clean up: |
719 | The corresponding EV::check watcher will then clean up: |
349 | |
720 | |
350 | our $snmp_check = EV::check sub { |
721 | our $snmp_check = EV::check sub { |
351 | # destroy all watchers |
722 | # destroy all watchers |
352 | @snmp_watcher = (); |
723 | @snmp_watcher = (); |
353 | |
724 | |
354 | # make the dispatcher handle any new stuff |
725 | # make the dispatcher handle any new stuff |
|
|
726 | ... not shown |
355 | }; |
727 | }; |
356 | |
728 | |
357 | The callbacks of the created watchers will not be called as the |
729 | The callbacks of the created watchers will not be called as the |
358 | watchers are destroyed before this cna happen (remember EV::check |
730 | watchers are destroyed before this cna happen (remember EV::check |
359 | gets called first). |
731 | gets called first). |
360 | |
732 | |
361 | The "check_ns" variant doesn't start (activate) the newly created |
733 | The "check_ns" variant doesn't start (activate) the newly created |
362 | watcher. |
734 | watcher. |
363 | |
735 | |
|
|
736 | FORK WATCHERS - the audacity to resume the event loop after a fork |
|
|
737 | Fork watchers are called when a "fork ()" was detected. The invocation |
|
|
738 | is done before the event loop blocks next and before "check" watchers |
|
|
739 | are being called, and only in the child after the fork. |
|
|
740 | |
|
|
741 | $w = EV::fork $callback |
|
|
742 | $w = EV::fork_ns $callback |
|
|
743 | $w = $loop->fork ($callback) |
|
|
744 | $w = $loop->fork_ns ($callback) |
|
|
745 | Call the callback before the event loop is resumed in the child |
|
|
746 | process after a fork. |
|
|
747 | |
|
|
748 | The "fork_ns" variant doesn't start (activate) the newly created |
|
|
749 | watcher. |
|
|
750 | |
|
|
751 | EMBED WATCHERS - when one backend isn't enough... |
|
|
752 | This is a rather advanced watcher type that lets you embed one event |
|
|
753 | loop into another (currently only IO events are supported in the |
|
|
754 | embedded loop, other types of watchers might be handled in a delayed or |
|
|
755 | incorrect fashion and must not be used). |
|
|
756 | |
|
|
757 | See the libev documentation at |
|
|
758 | <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code |
|
|
759 | _when_one_backend_> for more details. |
|
|
760 | |
|
|
761 | In short, this watcher is most useful on BSD systems without working |
|
|
762 | kqueue to still be able to handle a large number of sockets: |
|
|
763 | |
|
|
764 | my $socket_loop; |
|
|
765 | |
|
|
766 | # check wether we use SELECT or POLL _and_ KQUEUE is supported |
|
|
767 | if ( |
|
|
768 | (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT)) |
|
|
769 | && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE) |
|
|
770 | ) { |
|
|
771 | # use kqueue for sockets |
|
|
772 | $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV; |
|
|
773 | } |
|
|
774 | |
|
|
775 | # use the default loop otherwise |
|
|
776 | $socket_loop ||= EV::default_loop; |
|
|
777 | |
|
|
778 | $w = EV::embed $otherloop, $callback |
|
|
779 | $w = EV::embed_ns $otherloop, $callback |
|
|
780 | $w = $loop->embed ($otherloop, $callback) |
|
|
781 | $w = $loop->embed_ns ($otherloop, $callback) |
|
|
782 | Call the callback when the embedded event loop ($otherloop) has any |
|
|
783 | I/O activity. The $callback should alwas be specified as "undef" in |
|
|
784 | this version of EV, which means the embedded event loop will be |
|
|
785 | managed automatically. |
|
|
786 | |
|
|
787 | The "embed_ns" variant doesn't start (activate) the newly created |
|
|
788 | watcher. |
|
|
789 | |
|
|
790 | ASYNC WATCHERS - how to wake up another event loop |
|
|
791 | Async watchers are provided by EV, but have little use in perl directly, |
|
|
792 | as perl neither supports threads nor direct access to signal handlers or |
|
|
793 | other contexts where they could be of value. |
|
|
794 | |
|
|
795 | It is, however, possible to use them from the XS level. |
|
|
796 | |
|
|
797 | Please see the libev documentation for further details. |
|
|
798 | |
|
|
799 | $w = EV::async $callback |
|
|
800 | $w = EV::async_ns $callback |
|
|
801 | $w->send |
|
|
802 | $bool = $w->async_pending |
|
|
803 | |
|
|
804 | PERL SIGNALS |
|
|
805 | While Perl signal handling (%SIG) is not affected by EV, the behaviour |
|
|
806 | with EV is as the same as any other C library: Perl-signals will only be |
|
|
807 | handled when Perl runs, which means your signal handler might be invoked |
|
|
808 | only the next time an event callback is invoked. |
|
|
809 | |
|
|
810 | The solution is to use EV signal watchers (see "EV::signal"), which will |
|
|
811 | ensure proper operations with regards to other event watchers. |
|
|
812 | |
|
|
813 | If you cannot do this for whatever reason, you can also force a watcher |
|
|
814 | to be called on every event loop iteration by installing a "EV::check" |
|
|
815 | watcher: |
|
|
816 | |
|
|
817 | my $async_check = EV::check sub { }; |
|
|
818 | |
|
|
819 | This ensures that perl gets into control for a short time to handle any |
|
|
820 | pending signals, and also ensures (slightly) slower overall operation. |
|
|
821 | |
364 | THREADS |
822 | THREADS |
365 | Threads are not supported by this in any way. Perl pseudo-threads is |
823 | Threads are not supported by this module in any way. Perl pseudo-threads |
366 | evil stuff and must die. |
824 | is evil stuff and must die. As soon as Perl gains real threads I will |
|
|
825 | work on thread support for it. |
|
|
826 | |
|
|
827 | FORK |
|
|
828 | Most of the "improved" event delivering mechanisms of modern operating |
|
|
829 | systems have quite a few problems with fork(2) (to put it bluntly: it is |
|
|
830 | not supported and usually destructive). Libev makes it possible to work |
|
|
831 | around this by having a function that recreates the kernel state after |
|
|
832 | fork in the child. |
|
|
833 | |
|
|
834 | On non-win32 platforms, this module requires the pthread_atfork |
|
|
835 | functionality to do this automatically for you. This function is quite |
|
|
836 | buggy on most BSDs, though, so YMMV. The overhead for this is quite |
|
|
837 | negligible, because everything the function currently does is set a flag |
|
|
838 | that is checked only when the event loop gets used the next time, so |
|
|
839 | when you do fork but not use EV, the overhead is minimal. |
|
|
840 | |
|
|
841 | On win32, there is no notion of fork so all this doesn't apply, of |
|
|
842 | course. |
367 | |
843 | |
368 | SEE ALSO |
844 | SEE ALSO |
369 | L<EV::DNS>, L<EV::AnyEvent>. |
845 | EV::ADNS (asynchronous DNS), Glib::EV (makes Glib/Gtk2 use EV as event |
|
|
846 | loop), EV::Glib (embed Glib into EV), Coro::EV (efficient coroutines |
|
|
847 | with EV), Net::SNMP::EV (asynchronous SNMP), AnyEvent for event-loop |
|
|
848 | agnostic and portable event driven programming. |
370 | |
849 | |
371 | AUTHOR |
850 | AUTHOR |
372 | Marc Lehmann <schmorp@schmorp.de> |
851 | Marc Lehmann <schmorp@schmorp.de> |
373 | http://home.schmorp.de/ |
852 | http://home.schmorp.de/ |
374 | |
853 | |