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=head1 NAME |
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Coro::Signal - coroutine signals (binary semaphores) |
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=head1 SYNOPSIS |
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use Coro::Signal; |
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$sig = new Coro::Signal; |
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$sig->wait; # wait for signal |
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# ... some other "thread" |
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$sig->send; |
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=head1 DESCRIPTION |
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This module implements signal/binary semaphores/condition variables |
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(basically all the same thing). You can wait for a signal to occur or send |
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it, in which case it will wake up one waiter, or it can be broadcast, |
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waking up all waiters. |
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=over 4 |
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=cut |
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package Coro::Signal; |
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BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") } |
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use Coro (); |
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$VERSION = 4.746; |
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=item $s = new Coro::Signal; |
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Create a new signal. |
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=cut |
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sub new { |
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# [flag, [pid's]] |
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bless [], $_[0]; |
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} |
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=item $s->wait |
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Wait for the signal to occur. Returns immediately if the signal has been |
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sent before. |
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Signals are not reliable: this function might return spuriously without |
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the signal being sent. This means you must always test for the condition |
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you are waiting for. |
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(If this is a real problem for you the situation might be remedied in a |
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future version). |
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=item $status = $s->timed_wait ($timeout) |
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Like C<wait>, but returns false if no signal happens within $timeout |
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seconds, otherwise true. |
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See C<wait> for some reliability concerns. |
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=cut |
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sub wait { |
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unless (delete $_[0][0]) { |
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push @{$_[0][1]}, $Coro::current; |
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&Coro::schedule; |
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} |
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} |
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sub timed_wait { |
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require Coro::Timer; |
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my $timeout = Coro::Timer::timeout($_[1]); |
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unless (delete $_[0][0]) { |
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push @{$_[0][1]}, $Coro::current; |
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&Coro::schedule; |
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return 0 if $timeout; |
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} |
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1 |
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} |
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=item $s->send |
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Send the signal, waking up I<one> waiting process or remember the signal |
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if no process is waiting. |
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=cut |
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sub send { |
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$_[0][0] = 1; |
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(shift @{$_[0][1]})->ready if @{$_[0][1]}; |
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} |
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=item $s->broadcast |
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Send the signal, waking up I<all> waiting process. If no process is |
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waiting the signal is lost. |
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=cut |
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sub broadcast { |
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if (my $waiters = delete $_[0][1]) { |
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$_->ready for @$waiters; |
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} |
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} |
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=item $s->awaited |
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Return true when the signal is being awaited by some process. |
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=cut |
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sub awaited { |
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! ! @{$_[0][1]} |
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} |
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1; |
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=back |
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=head1 BUGS |
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This implementation is not currently very robust when the process is woken |
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up by other sources, i.e. C<wait> might return early. |
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=head1 AUTHOR |
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|
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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=cut |
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