coro::channel(3pm) [debian man page]

Channel(3pm)						User Contributed Perl Documentation					      Channel(3pm)

NAME

       Coro::Channel - message queues

SYNOPSIS

	use Coro;

	$q1 = new Coro::Channel <maxsize>;

	$q1->put ("xxx");
	print $q1->get;

	die unless $q1->size;

DESCRIPTION

       A Coro::Channel is the equivalent of a unix pipe (and similar to amiga message ports): you can put things into it on one end and read
       things out of it from the other end. If the capacity of the Channel is maxed out writers will block. Both ends of a Channel can be
       read/written from by as many coroutines as you want concurrently.

       You don't have to load "Coro::Channel" manually, it will be loaded automatically when you "use Coro" and call the "new" constructor.

       $q = new Coro:Channel $maxsize
	   Create a new channel with the given maximum size (practically unlimited if "maxsize" is omitted). Giving a size of one gives you a
	   traditional channel, i.e. a queue that can store only a single element (which means there will be no buffering, and "put" will wait
	   until there is a corresponding "get" call). To buffer one element you have to specify 2, and so on.

       $q->put ($scalar)
	   Put the given scalar into the queue.

       $q->get
	   Return the next element from the queue, waiting if necessary.

       $q->shutdown
	   Shuts down the Channel by pushing a virtual end marker onto it: This changes the behaviour of the Channel when it becomes or is empty
	   to return "undef", almost as if infinitely many "undef" elements have been put into the queue.

	   Specifically, this function wakes up any pending "get" calls and lets them return "undef", the same on future "get" calls. "size" will
	   return the real number of stored elements, though.

	   Another way to describe the behaviour is that "get" calls will not block when the queue becomes empty but immediately return "undef".
	   This means that calls to "put" will work normally and the data will be returned on subsequent "get" calls.

	   This method is useful to signal the end of data to any consumers, quite similar to an end of stream on e.g. a tcp socket: You have one
	   or more producers that "put" data into the Channel and one or more consumers who "get" them. When all producers have finished producing
	   data, a call to "shutdown" signals this fact to any consumers.

       $q->size
	   Return the number of elements waiting to be consumed. Please note that:

	     if ($q->size) {
		my $data = $q->get;
		...
	     }

	   is not a race condition but instead works just fine. Note that the number of elements that wait can be larger than $maxsize, as it
	   includes any coroutines waiting to put data into the channel (but not any shutdown condition).

	   This means that the number returned is precisely the number of calls to "get" that will succeed instantly and return some data. Calling
	   "shutdown" has no effect on this number.

AUTHOR

	Marc Lehmann <schmorp@schmorp.de>
	http://home.schmorp.de/

perl v5.14.2							    2012-04-13							      Channel(3pm)

Check Out this Related Man Page

Select(3pm)						User Contributed Perl Documentation					       Select(3pm)

NAME

       Coro::Select - a (slow but coro-aware) replacement for CORE::select

SYNOPSIS

	use Coro::Select;	   # replace select globally (be careful, see below)
	use Core::Select 'select'; # only in this module
	use Coro::Select ();	   # use Coro::Select::select

DESCRIPTION

       This module tries to create a fully working replacement for perl's "select" built-in, using "AnyEvent" watchers to do the job, so other
       threads can run in parallel to any select user. As many libraries that only have a blocking API do not use global variables and often use
       select (or IO::Select), this effectively makes most such libraries "somewhat" non-blocking w.r.t. other threads.

       This implementation works fastest when only very few bits are set in the fd set(s).

       To be effective globally, this module must be "use"'d before any other module that uses "select", so it should generally be the first
       module "use"'d in the main program. Note that overriding "select" globally might actually cause problems, as some "AnyEvent" backends use
       "select" themselves, and asking AnyEvent to use Coro::Select, which in turn asks AnyEvent will not quite work.

       You can also invoke it from the commandline as "perl -MCoro::Select".

       To override select only for a single module (e.g. "Net::DBus::Reactor"), use a code fragment like this to load it:

	  {
	     package Net::DBus::Reactor;
	     use Coro::Select qw(select);
	     use Net::DBus::Reactor;
	  }

       Some modules (notably POE::Loop::Select) directly call "CORE::select". For these modules, we need to patch the opcode table by sandwiching
       it between calls to "Coro::Select::patch_pp_sselect" and "Coro::Select::unpatch_pp_sselect":

	BEGIN {
	   use Coro::Select ();
	   Coro::Select::patch_pp_sselect;
	   require evil_poe_module_using_CORE::SELECT;
	   Coro::Select::unpatch_pp_sselect;
	}

BUGS

       For performance reasons, Coro::Select's select function might not properly detect bad file descriptors (but relying on EBADF is inherently
       non-portable).

SEE ALSO

       Coro::LWP.

AUTHOR

	Marc Lehmann <schmorp@schmorp.de>
	http://home.schmorp.de/

perl v5.14.2							    2012-04-13							       Select(3pm)

Linux and UNIX Man Pages

coro::channel(3pm) [debian man page]

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