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=head1 NAME |
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|
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Coro - coroutine process abstraction |
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|
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=head1 SYNOPSIS |
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|
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use Coro; |
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|
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async { |
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# some asynchronous thread of execution |
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}; |
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|
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# alternatively create an async process like this: |
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|
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sub some_func : Coro { |
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# some more async code |
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} |
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|
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cede; |
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|
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=head1 DESCRIPTION |
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|
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This module collection manages coroutines. Coroutines are similar to |
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Threads but don't run in parallel. |
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|
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This module is still experimental, see the BUGS section below. |
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|
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In this module, coroutines are defined as "callchain + lexical variables |
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+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
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callchain, it's own set of lexicals and it's own set of perl's most |
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important global variables. |
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|
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=cut |
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|
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package Coro; |
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|
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no warnings qw(uninitialized); |
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|
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use Coro::State; |
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|
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use base Exporter; |
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|
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$VERSION = 0.5; |
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|
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@EXPORT = qw(async cede schedule terminate current); |
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%EXPORT_TAGS = ( |
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prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
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); |
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@EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
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|
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{ |
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my @async; |
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my $init; |
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|
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# this way of handling attributes simply is NOT scalable ;() |
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sub import { |
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Coro->export_to_level(1, @_); |
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my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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my ($package, $ref) = (shift, shift); |
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my @attrs; |
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for (@_) { |
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if ($_ eq "Coro") { |
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push @async, $ref; |
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unless ($init++) { |
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eval q{ |
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sub INIT { |
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&async(pop @async) while @async; |
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} |
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}; |
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} |
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} else { |
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push @attrs, $_; |
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} |
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} |
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return $old ? $old->($package, $ref, @attrs) : @attrs; |
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}; |
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} |
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|
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} |
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|
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=item $main |
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|
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This coroutine represents the main program. |
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|
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=cut |
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|
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our $main = new Coro; |
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|
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=item $current (or as function: current) |
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|
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The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
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|
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=cut |
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|
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# maybe some other module used Coro::Specific before... |
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if ($current) { |
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$main->{specific} = $current->{specific}; |
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} |
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|
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our $current = $main; |
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|
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sub current() { $current } |
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|
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=item $idle |
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|
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The coroutine to switch to when no other coroutine is running. The default |
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implementation prints "FATAL: deadlock detected" and exits. |
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|
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=cut |
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|
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# should be done using priorities :( |
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our $idle = new Coro sub { |
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print STDERR "FATAL: deadlock detected\n"; |
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exit(51); |
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}; |
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|
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# this coroutine is necessary because a coroutine |
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# cannot destroy itself. |
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my @destroy; |
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my $manager = new Coro sub { |
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while() { |
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# by overwriting the state object with the manager we destroy it |
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# while still being able to schedule this coroutine (in case it has |
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# been readied multiple times. this is harmless since the manager |
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# can be called as many times as neccessary and will always |
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# remove itself from the runqueue |
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(pop @destroy)->{_coro_state} = $manager->{_coro_state} while @destroy; |
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&schedule; |
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} |
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}; |
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|
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# static methods. not really. |
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|
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=head2 STATIC METHODS |
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|
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Static methods are actually functions that operate on the current process only. |
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|
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=over 4 |
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|
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=item async { ... } [@args...] |
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|
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Create a new asynchronous process and return it's process object |
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(usually unused). When the sub returns the new process is automatically |
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terminated. |
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|
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# create a new coroutine that just prints its arguments |
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async { |
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print "@_\n"; |
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} 1,2,3,4; |
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|
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The coderef you submit MUST NOT be a closure that refers to variables |
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in an outer scope. This does NOT work. Pass arguments into it instead. |
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|
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=cut |
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|
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sub async(&@) { |
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my $pid = new Coro @_; |
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$manager->ready; # this ensures that the stack is cloned from the manager |
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$pid->ready; |
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$pid; |
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} |
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|
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=item schedule |
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|
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Calls the scheduler. Please note that the current process will not be put |
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into the ready queue, so calling this function usually means you will |
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never be called again. |
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|
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=cut |
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|
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=item cede |
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|
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"Cede" to other processes. This function puts the current process into the |
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ready queue and calls C<schedule>, which has the effect of giving up the |
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current "timeslice" to other coroutines of the same or higher priority. |
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|
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=cut |
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|
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=item terminate |
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|
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Terminates the current process. |
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|
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Future versions of this function will allow result arguments. |
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|
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=cut |
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|
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sub terminate { |
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$current->cancel; |
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&schedule; |
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die; # NORETURN |
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} |
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|
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=back |
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|
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# dynamic methods |
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|
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=head2 PROCESS METHODS |
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|
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These are the methods you can call on process objects. |
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|
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=over 4 |
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|
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=item new Coro \&sub [, @args...] |
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|
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Create a new process and return it. When the sub returns the process |
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automatically terminates. To start the process you must first put it into |
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the ready queue by calling the ready method. |
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|
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The coderef you submit MUST NOT be a closure that refers to variables |
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in an outer scope. This does NOT work. Pass arguments into it instead. |
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|
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=cut |
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|
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sub _newcoro { |
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terminate &{+shift}; |
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} |
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|
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sub new { |
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my $class = shift; |
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bless { |
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_coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
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}, $class; |
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} |
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|
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=item $process->ready |
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Put the current process into the ready queue. |
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|
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=cut |
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|
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=item $process->cancel |
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Like C<terminate>, but terminates the specified process instead. |
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|
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=cut |
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|
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sub cancel { |
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push @destroy, $_[0]; |
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$manager->ready; |
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&schedule if $current == $_[0]; |
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} |
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|
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=item $oldprio = $process->prio($newprio) |
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|
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Sets the priority of the process. Higher priority processes get run before |
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lower priority processes. Priorities are smalled signed integer (currently |
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-4 .. +3), that you can refer to using PRIO_xxx constants (use the import |
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tag :prio to get then): |
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PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
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3 > 1 > 0 > -1 > -3 > -4 |
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|
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# set priority to HIGH |
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current->prio(PRIO_HIGH); |
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|
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The idle coroutine ($Coro::idle) always has a lower priority than any |
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existing coroutine. |
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|
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Changing the priority of the current process will take effect immediately, |
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but changing the priority of processes in the ready queue (but not |
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running) will only take effect after the next schedule (of that |
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process). This is a bug that will be fixed in some future version. |
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|
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=cut |
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|
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sub prio { |
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my $old = $_[0]{prio}; |
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$_[0]{prio} = $_[1] if @_ > 1; |
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$old; |
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} |
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|
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=item $newprio = $process->nice($change) |
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|
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Similar to C<prio>, but subtract the given value from the priority (i.e. |
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higher values mean lower priority, just as in unix). |
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|
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=cut |
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|
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sub nice { |
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$_[0]{prio} -= $_[1]; |
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} |
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|
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=back |
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|
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=cut |
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|
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1; |
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|
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=head1 BUGS/LIMITATIONS |
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|
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- you must make very sure that no coro is still active on global destruction. |
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very bad things might happen otherwise (usually segfaults). |
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- this module is not thread-safe. You must only ever use this module from |
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the same thread (this requirement might be loosened in the future to |
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allow per-thread schedulers, but Coro::State does not yet allow this). |
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|
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=head1 SEE ALSO |
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|
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L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
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L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, |
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L<Coro::Handle>, L<Coro::Socket>. |
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|
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=head1 AUTHOR |
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|
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Marc Lehmann <pcg@goof.com> |
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http://www.goof.com/pcg/marc/ |
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|
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=cut |
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|
