Pool::collect

(PECL pthreads >= 2.0.0)

Pool::collectCollect references to completed tasks

Description

public int Pool::collect ([ Callable $collector ] )

Allows the pool to collect references determined to be garbage by the optionally given collector.

Parameters

collector

A Callable collector that returns a boolean on whether the task can be collected or not. Only in rare cases should a custom collector need to be used.

Return Values

The number of remaining tasks in the pool to be collected.

Changelog

Version Description
v3 An integer is now returned, and the collector parameter is now optional.

Examples

Example #1 A basic example of Pool::collect()

<?php
$pool 
= new Pool(4);

for (
$i 0$i 15; ++$i) {
    
$pool->submit(new class extends Threaded {});
}

while (
$pool->collect()); // blocks until all tasks have finished executing

$pool->shutdown();

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User Contributed Notes 3 notes

up
5
your dot brother dot t at hotmail dot com
2 years ago
The example code crashes and made me waste 2 working days
First of all, `Stackable` has no attribute named $worker or it's access method made it inaccessible.

Secondly, `Stackable` also doesn't have `getThreadId()` . It's best practice to use `Thread` class for realization of a thread since it has more control functions. It's better to use `Stackable` for object storage and use it's `run()` as its initialization.

The working example is

<?php
   
class MyWork extends Thread {
        protected
$complete;

        public function
__construct() {
           
$this->complete = false;
        }

        public function
run() {
           
printf(
               
"Hello from %s in Thread #%lu\n",
               
__CLASS__, $this->getThreadId());
           
$this->complete = true;
        }

        public function
isComplete() {
            return
$this->complete;
        }
    }

    class
Something {}

    class
MyWorker extends Worker {

        public function
__construct(Something $something) {
           
$this->something = $something;
        }

        public function
run() {
           
/** ... **/
       
}
    }

   
$pool = new Pool(8, \MyWorker::class, [new Something()]);
   
$pool->submit(new MyWork());

   
usleep(1000);

   
$pool->collect(function($work){
        return
$work->isComplete();
    });
   
var_dump($pool);
?>
up
2
meadowsjared at gmail dot com
1 year ago
Please note, when using the collect function, it's important that you extend the pool class so you can keep checking for finished threads until they're all done.

<?php
class TestWork extends Threaded {
    protected
$complete;
   
//$pData is the data sent to your worker thread to do it's job.
   
public function __construct($pData){
       
//transfer all the variables to local variables
       
$this->complete = false;
       
$this->testData = $pData;
    }
   
//This is where all of your work will be done.
   
public function run(){
       
usleep(2000000); //sleep 2 seconds to simulate a large job
       
$this->complete = true;
    }
    public function
isGarbage() {
        return
$this->complete;
    }
}
class
ExamplePool extends Pool
{
    public
$data = array();
    public function
process()
    {
       
// Run this loop as long as we have
        // jobs in the pool
       
while (count($this->work)) {
           
$this->collect(function (TestWork $task) {
               
// If a task was marked as done
                // collect its results
               
if ($task->isGarbage()) {
                   
$tmpObj = new stdclass();
                   
$tmpObj->complete = $task->complete;
                   
//this is how you get your completed data back out [accessed by $pool->process()]
                   
$this->data[] = $tmpObj;
                }
                return
$task->isGarbage();
            });
        }
       
// All jobs are done
        // we can shutdown the pool
       
$this->shutdown();
        return
$this->data;
    }
}
$pool = new ExamplePool(3);
$testData = 'asdf';
for(
$i=0;$i<5;$i++) {
   
$pool->submit(new TestWork($testData));
}
$retArr = $pool->process(); //get all of the results
echo '<pre>';
print_r($retArr); //return the array of results (and maybe errors)
echo '</pre>';
?>
up
0
l00k at protonmail dot com
13 days ago
This example demonstrates various aspects of MTP with pthreads - esspecially worth of note is bidirectional communication with child threads.
I could not find anything about that so I would like to present you my research result.

<?php

class Model
{
   
    public
$id;
    public
$value;
   
}

class
Connection
   
extends Worker
{
   
    protected static
$link;
   
   
    public function
__construct($hostname, $username, $password, $database, $port = 3306)
    {
       
$this->hostname = $hostname;
       
$this->username = $username;
       
$this->password = $password;
       
$this->database = $database;
       
$this->port = $port;
    }
   
    public function
getConnection()
    {
        if(!
self::$link)
        {
            echo
'Thread: '. $this->getThreadId() ." Connecting to db\n";
           
self::$link = new \PDO(...);
        }
       
        return
self::$link;
    }
   
}

/** @property Connection $worker */
class QueryTask
   
extends Threaded
{
   
    public
$data;
    public
$result;
   
    protected
$_complete;
   
   
    public function
__construct(Model $data)
    {
       
$this->_complete = false;
       
$this->data = $data;
    }
   
    public function
run()
    {
       
/** @var \PDO $pdo */
       
$pdo = $this->worker->getConnection();
       
       
$text = 'Thread: '. $this->worker->getThreadId() .' Job: '. $this->data->id .' Data: '. $this->data->value;
       
       
$t = microtime(true);
       
       
$stmt = $pdo->prepare("
            INSERT INTO `test` (`id`, `text`) VALUES (NULL, '"
. $text ."')
        "
);
       
$stmt->execute();
       
       
$dt = microtime(true) - $t;
       
       
$result = (int) $stmt->rowCount();
       
        echo
$text .' Result: '. $result .' Exec time: '. $dt ."s\n";
       
       
$this->result = $result;
       
$this->_complete = true;
    }
   
    public function
isGarbage() : bool
   
{
        return
$this->_complete;
    }
   
}

$t = microtime(true);

// uruchomienie
$pool = new Pool(5, 'Connection', [ 'localhost', 'root', 'password', 'test' ]);

// zadania
$tasks = 10;

for(
$i=0; $i<$tasks; ++$i)
{
   
$object = new Model();
   
$object->id = $i;
   
$object->value = rand();

   
$pool->submit(new QueryTask($object));
}

// oczekiwanie na zakonczenie
$data = [];

while(
1)
{
   
$newData = [];

   
$pool->collect(function(QueryTask $task) use (&$newData) {
        if(
$task->isGarbage())
        {
           
$tmpObj = new stdclass();
           
$tmpObj->complete = $task->complete;
           
           
$newData[ $task->data->id ] = $task->data->value;
        }
       
        return
$task->isGarbage();
    });
   
   
$data = array_merge($data, $newData);
   
    if(
count($data) == $tasks)
        break;
   
   
usleep(100000);
}

var_dump($data);
?>

Result:
Thread: 6796 Connecting to db
Thread: 3156 Connecting to db
Thread: 9040 Connecting to db
Thread: 7748 Connecting to db
Thread: 8836 Connecting to db
Job: 0 Done in: 0.0070011615753174s
Job: 4 Done in: 0.0069999694824219s
Job: 2 Done in: 0.0090010166168213s
Job: 3 Done in: 0.0090010166168213s
Job: 1 Done in: 0.003000020980835s
Job: 5 Done in: 0.0069999694824219s
Job: 7 Done in: 0.0079998970031738s
Job: 6 Done in: 0.0049998760223389s
Job: 9 Done in: 0.0079998970031738s
Job: 8 Done in: 0.0069999694824219s

array(10) {
  [0] =>
  int(17730)
  [1] =>
  int(18771)
  [2] =>
  int(12944)
  [3] =>
  int(6025)
  [4] =>
  int(29582)
  [5] =>
  int(10159)
  [6] =>
  int(26556)
  [7] =>
  int(9029)
  [8] =>
  int(15002)
  [9] =>
  int(4043)
}

Things worth noting here:
1. Constructing of 5 workers for 10 tasks. 5 last task are runned on existing threads with already set up connection to db.
2. You can "send" data to thread by creating new task and submiting it.
3. You can retrive result by collect function.
4. You can pass simple object to task constructor.
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