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=head1 NAME |
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|
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Coro - create and manage simple coroutines |
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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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$new = new Coro sub { |
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print "in coroutine, switching back\n"; |
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$new->transfer($main); |
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print "in coroutine again, switching back\n"; |
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$new->transfer($main); |
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}; |
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|
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$main = new Coro; |
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|
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print "in main, switching to coroutine\n"; |
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$main->transfer($new); |
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print "back in main, switch to coroutine again\n"; |
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$main->transfer($new); |
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print "back in main\n"; |
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|
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=head1 DESCRIPTION |
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|
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This module implements coroutines. Coroutines, similar to continuations, |
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allow you to run more than one "thread of execution" in parallel. Unlike |
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threads this, only voluntary switching is used so locking problems are |
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greatly reduced. |
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|
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Although this is the "main" module of the Coro family it provides only |
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low-level functionality. See L<Coro::Process> and related modules for a |
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more useful process abstraction including scheduling. |
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|
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=over 4 |
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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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BEGIN { |
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$VERSION = 0.03; |
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|
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require XSLoader; |
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XSLoader::load Coro, $VERSION; |
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} |
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|
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=item $coro = new [$coderef [, @args]] |
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|
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Create a new coroutine and return it. The first C<transfer> call to this |
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coroutine will start execution at the given coderef. If, the subroutine |
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returns it will be executed again. |
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|
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If the coderef is omitted this function will create a new "empty" |
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coroutine, i.e. a coroutine that cannot be transfered to but can be used |
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to save the current coroutine in. |
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|
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=cut |
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|
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sub new { |
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my $class = $_[0]; |
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my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; |
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bless _newprocess { |
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do { |
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eval { &$proc }; |
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if ($@) { |
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$error_msg = $@; |
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$error_coro = _newprocess { }; |
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&transfer($error_coro, $error); |
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} |
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} while (1); |
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}, $class; |
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} |
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|
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=item $prev->transfer($next) |
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|
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Save the state of the current subroutine in C<$prev> and switch to the |
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coroutine saved in C<$next>. |
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|
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The "state" of a subroutine only ever includes scope, i.e. lexical |
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variables and the current execution state. It does not save/restore any |
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global variables such as C<$_> or C<$@> or any other special or non |
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special variables. So remember that every function call that might call |
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C<transfer> (such as C<Coro::Channel::put>) might clobber any global |
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and/or special variables. Yes, this is by design ;) You cna always create |
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your own process abstraction model that saves these variables. |
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|
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The easiest way to do this is to create your own scheduling primitive like this: |
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|
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sub schedule { |
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local ($_, $@, ...); |
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$old->transfer($new); |
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} |
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|
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=cut |
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|
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# I call the _transfer function from a perl function |
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# because that way perl saves all important things on |
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# the stack. Actually, I'd do it from within XS, but |
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# I couldn't get it to work. |
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sub transfer { |
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_transfer($_[0], $_[1]); |
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} |
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|
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=item $error, $error_msg, $error_coro |
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|
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This coroutine will be called on fatal errors. C<$error_msg> and |
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C<$error_coro> return the error message and the error-causing coroutine |
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(NOT an object) respectively. This API might change. |
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|
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=cut |
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|
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$error_msg = |
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$error_coro = undef; |
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|
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$error = _newprocess { |
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print STDERR "FATAL: $error_msg\nprogram aborted\n"; |
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exit 50; |
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}; |
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|
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1; |
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|
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=back |
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|
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=head1 BUGS |
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|
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This module has not yet been extensively tested. |
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|
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=head1 SEE ALSO |
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|
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L<Coro::Process>, L<Coro::Signal>. |
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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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|
