Steffen Ullrich > Net-SIP > Net::SIP::Dispatcher::Eventloop



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Net::SIP::Dispatcher::Eventloop - simple event loop for Net::SIP::Dispatcher


  my $loop = Net::SIP::Dispatcher::Eventloop->new;
  $loop->addFD( $fd, $callback );
  $loop->add_timer( 10,$callback );


The package implements a simple event loop. It's not optimized for speed but it is provided as a simple implementation in case the users application does not has an event loop yet.

Because the eventloop object can be given in the constructor of Net::SIP::Dispatcher you might provide an alternative implementation, which implemented the described methods.



Creates new event loop, returns created object



Adds file handle HANDLE to the event loop, so that CALLBACK gets triggered if HANDLE is readable (RW 0) or writeable (RW 1). Instead of 0 and 1 one can also use the exported constants EV_READ and EV_WRITE. CALLBACK is a callback accepted by invoke_callback in Net::SIP::Util. The callback will be invoked with HANDLE as an additional argument.

NAME can be used to aid debugging, it will be shown in the debug messages once the FD gets ready.

If there was already a callback for HANDLE it gets replaced by the new one.

IMPORTANT NOTE: CALLBACK gets triggered if HANDLE *is* readable inside the loop, not if HANDLE *gets* readable. Unlike with Event::Lib or similar the CALLBACK is not triggered by the edge, but by the level (like poll(2) or select(2)). So if 2 bytes come in at the handle and one reads only 1 byte in the callback the callback gets triggered again for more data. You have to watch this, if you want to integrate Net::SIP with your existing event loop.

delFD (HANDLE, [RW])

If RW is 0 (EV_READ) no more checking for readability of HANDLE will be done. If RW is 1 (EV_WRITE) no more checking for writeability of HANDLE will be done. If RW is not given it will remove HANDLE from the loop completely, i.e. for both read and write.

add_timer( WHEN, CALLBACK, [ REPEAT ] )

Adds timer which gets triggered at WHEN or now + WHEN. Depending on the value of WHEN it gets interpreted as the number of seconds since 1970-01-01 (when it's really big) or as a relative time (when it's not that big). WHEN can be floating point for subseconds resolution.

CALLBACK is a callback accepted by invoke_callback in Net::SIP::Util. It gets invoked with the timer object (see later) as an additional argument, which has a method cancel for canceling the (repeating) timer.

REPEAT is the number of seconds between each invocation of the timer. If greater then 0 (subsection resulution possible) the callback will be called each REPEAT seconds, after it was called the first time at WHEN.

The method will return an object which has a method cancel which can be used to cancel the timer before it gets triggered (or gets triggered the next time in case of repeating timers).


Returns the current loop time in subseconds resolution (using gettimeofday from Time::HiRes). This is not the current time, but the time, when the last event in the loop occurred (e.g. when the select(2) call returned)

loop ( [ TIMEOUT, \@STOPVAR ] )

The main loop, e.g. continuiosly checks timers and file handles for the events and calls callbacks.

If TIMEOUT is given it will run the loop for at most TIMEOUT seconds, then the method will return. Undefined TIMEOUT means that it will never return because of timeout and TIMEOUT of 0 means that it will check all timers and handles only once and then return.

@STOPVAR is a list of scalar references. These scalars are expected to be changed from the callbacks, so it will check after each loop cycle, e.g. after all callbacks are called (timers and handles) if any of these scalars is TRUE, in which case it will end the loop.

The behavior with STOPVAR cannot be found in most existing event loops. If you want to integrate Net::SIP with your own event loop you migth simply wrap all callbacks given in addFD and add_timer in another callback which at the end checks the stopvars and terminates the 3rd-party loop in a loop-specific way.

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