TaskSet::getIterator

Get an iterator for traversing results with automatic cleanup.

TaskSet::getIterator ​

(PHP 8.6+, True Async 1.0)

php
public TaskSet::getIterator(): Iterator

Returns an iterator that yields results as tasks complete. TaskSet implements IteratorAggregate, so you can use foreach directly.

Each processed entry is automatically removed from the set, freeing memory and decreasing count().

Iterator Behavior ​

  • foreach suspends the current coroutine until the next result is available
  • The key is the same one assigned during spawn() or spawnWithKey()
  • The value is an array [mixed $result, ?Throwable $error]:
    • Success: [$result, null]
    • Error: [null, $error]
  • Iteration ends when the set is sealed and all tasks have been processed
  • If the set is not sealed, foreach suspends waiting for new tasks

Important: Without calling seal(), iteration will wait indefinitely.

Examples ​

Example #1 Streaming processing ​

php
<?php

use Async\TaskSet;

spawn(function() {
    $set = new TaskSet(concurrency: 5);

    for ($i = 0; $i < 100; $i++) {
        $set->spawn(fn() => processItem($items[$i]));
    }
    $set->seal();

    foreach ($set as $key => [$result, $error]) {
        if ($error !== null) {
            echo "Task $key: error — {$error->getMessage()}\n";
            continue;
        }
        echo "Task $key: done\n";
        // Entry removed, memory freed
    }

    echo $set->count() . "\n"; // 0
});

Example #2 Named keys ​

php
<?php

use Async\TaskSet;

spawn(function() {
    $set = new TaskSet();

    $set->spawnWithKey('users', fn() => fetchUsers());
    $set->spawnWithKey('orders', fn() => fetchOrders());
    $set->seal();

    foreach ($set as $key => [$result, $error]) {
        if ($error === null) {
            echo "$key: received " . count($result) . " records\n";
        }
    }
});

See Also ​