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@ -295,8 +295,8 @@ Example: This is basically the same thing that libev does internally, too. |
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=head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
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An event loop is described by a C<struct ev_loop *> (the C<struct> is |
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I<not> optional in case unless libev 3 compatibility is disabled, as libev |
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3 had an C<ev_loop> function colliding with the struct name). |
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I<not> optional in this case unless libev 3 compatibility is disabled, as |
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libev 3 had an C<ev_loop> function colliding with the struct name). |
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The library knows two types of such loops, the I<default> loop, which |
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supports signals and child events, and dynamically created event loops |
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@ -992,9 +992,10 @@ In the following description, uppercase C<TYPE> in names stands for the |
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watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
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watchers and C<ev_io_start> for I/O watchers. |
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A watcher is a structure that you create and register to record your |
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interest in some event. For instance, if you want to wait for STDIN to |
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become readable, you would create an C<ev_io> watcher for that: |
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A watcher is an opaque structure that you allocate and register to record |
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your interest in some event. To make a concrete example, imagine you want |
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to wait for STDIN to become readable, you would create an C<ev_io> watcher |
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for that: |
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static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
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{ |
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@ -1019,11 +1020,11 @@ stack). |
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Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
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or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
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Each watcher structure must be initialised by a call to C<ev_init |
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(watcher *, callback)>, which expects a callback to be provided. This |
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callback gets invoked each time the event occurs (or, in the case of I/O |
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watchers, each time the event loop detects that the file descriptor given |
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is readable and/or writable). |
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Each watcher structure must be initialised by a call to C<ev_init (watcher |
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*, callback)>, which expects a callback to be provided. This callback is |
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invoked each time the event occurs (or, in the case of I/O watchers, each |
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time the event loop detects that the file descriptor given is readable |
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and/or writable). |
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Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
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macro to configure it, with arguments specific to the watcher type. There |
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@ -1131,6 +1132,65 @@ thing, so beware. |
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=back |
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=head2 WATCHER STATES |
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There are various watcher states mentioned throughout this manual - |
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active, pending and so on. In this section these states and the rules to |
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transition between them will be described in more detail - and while these |
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rules might look complicated, they usually do "the right thing". |
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=over 4 |
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=item initialiased |
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Before a watcher can be registered with the event looop it has to be |
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initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
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C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
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In this state it is simply some block of memory that is suitable for use |
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in an event loop. It can be moved around, freed, reused etc. at will. |
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=item started/running/active |
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Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
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property of the event loop, and is actively waiting for events. While in |
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this state it cannot be accessed (except in a few documented ways), moved, |
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freed or anything else - the only legal thing is to keep a pointer to it, |
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and call libev functions on it that are documented to work on active watchers. |
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=item pending |
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If a watcher is active and libev determines that an event it is interested |
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in has occured (such as a timer expiring), it will become pending. It will |
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stay in this pending state until either it is stopped or its callback is |
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about to be invoked, so it is not normally pending inside the watcher |
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callback. |
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The watcher might or might not be active while it is pending (for example, |
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an expired non-repeating timer can be pending but no longer active). If it |
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is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
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but it is still property of the event loop at this time, so cannot be |
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moved, freed or reused. And if it is active the rules described in the |
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previous item still apply. |
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It is also possible to feed an event on a watcher that is not active (e.g. |
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via C<ev_feed_event>), in which case it becomes pending without being |
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active. |
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=item stopped |
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A watcher can be stopped implicitly by libev (in which case it might still |
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be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
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latter will clear any pending state the watcher might be in, regardless |
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of whether it was active or not, so stopping a watcher explicitly before |
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freeing it is often a good idea. |
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While stopped (and not pending) the watcher is essentially in the |
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initialised state, that is it can be reused, moved, modified in any way |
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you wish. |
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=back |
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=head2 GENERIC WATCHER FUNCTIONS |
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=over 4 |
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