an example used unbuffered channel.
<?php
use parallel\{Channel,Runtime};
$sum=function(array $a, Channel $ch) {
$sum=0;
foreach ($a as $v) {
$sum+=$v;
}
$ch->send($sum);
};
try {
$a=[7, 2, 8, 1, 4, 0, 9, 10];
//unbuffered channel
$runtime=new Runtime;
$ch2=new Channel;
$runtime->run($sum, [array_slice($a, 0, $num), $ch2]);
$runtime->run($sum, [array_slice($a, $num), $ch2]);
//receive from channel
$x=$ch2->recv();
$y=$ch2->recv();
$ch2->close();
echo "\nch2:", $x, "\t", $y, "\t", $x + $y, "\n";
} catch(Error $err) {
echo "\nError:", $err->getMessage();
} catch(Exception $e) {
echo "\nException:", $e->getMessage();
}
//output
//ch2:18 23 41
The parallel\Channel class
(0.9.0)
Unbuffered Channels
An unbuffered channel will block on calls to parallel\Channel::send() until there is a receiver, and block on calls to parallel\Channel::recv() until there is a sender. This means an unbuffered channel is not only a way to share data among tasks but also a simple method of synchronization.
An unbuffered channel is the fastest way to share data among tasks, requiring the least copying.
Buffered Channels
A buffered channel will not block on calls to parallel\Channel::send() until capacity is reached, calls to parallel\Channel::recv() will block until there is data in the buffer.
Closures over Channels
A powerful feature of parallel channels is that they allow the exchange of closures between tasks (and runtimes).
When a closure is sent over a channel the closure is buffered, it doesn't change the buffering of the channel transmitting the closure, but it does effect the static scope inside the closure: The same closure sent to different runtimes, or the same runtime, will not share their static scope.
This means that whenever a closure is executed that was transmitted by a channel, static state will be as it was when the closure was buffered.
Anonymous Channels
The anonymous channel constructor allows the programmer to avoid assigning names to every channel: parallel will generate a unique name for anonymous channels.
Class synopsis
final
parallel\Channel
{
/* Anonymous Constructor */
/* Access */
/* Sharing */
/* Closing */
/* Constant for Infinitely Buffered */
const
Infinite
;
}Table of Contents
- parallel\Channel::__construct — Channel Construction
- parallel\Channel::make — Access
- parallel\Channel::open — Access
- parallel\Channel::recv — Sharing
- parallel\Channel::send — Sharing
- parallel\Channel::close — Closing
add a note
User Contributed Notes 2 notes
rustysun ¶
12 days ago
rustysun ¶
13 days ago
<?php
use parallel\Channel;
function sum(array $a, Channel $ch) {
$sum=0;
foreach ($a as $v) {
$sum+=$v;
}
$ch->send($sum);
}
try {
$a=[7, 2, 8, 1, 4, 0, 9, 10];
$ch1=Channel::make('sum', 2);
$ch2=new Channel;
$num=count($a) / 2;
sum(array_slice($a, 0, $num), $ch1);
sum(array_slice($a, $num), $ch1);
//receive from channel
$x=$ch1->recv();
$y=$ch1->recv();
$ch1->close();
echo "\nch1:", $x, "\t", $y, "\t", $x + $y, "\n";
} catch(Error $err) {
echo "\nError:", $err->getMessage();
} catch(Exception $e) {
echo "\nException:", $e->getMessage();
}
