Add Pool parameter to function

Allows specifying a specific worker pool instead of the global pool.

src/functions.php

@@ -3,6 +3,7 @@
 namespace Amp\ParallelFunctions;
 
 use Amp\MultiReasonException;
+use Amp\Parallel\Worker\Pool;
 use Amp\ParallelFunctions\Internal\ParallelTask;
 use Amp\Promise;
 use Opis\Closure\SerializableClosure;
@@ -13,12 +14,13 @@ use function Amp\Promise\any;
 /**
  * Parallelizes a callable.
  *
- * @param callable $callable Callable to parallelize.
+ * @param callable  $callable Callable to parallelize.
+ * @param Pool|null $pool Worker pool instance to use or null to use the global pool.
  *
  * @return callable Callable executing in another thread / process.
  * @throws \Error If the passed callable is not safely serializable.
  */
-function parallel(callable $callable): callable {
+function parallel(callable $callable, Pool $pool = null): callable {
     try {
         if (\is_string($callable)) {
             $payload = \serialize($callable);
@@ -31,25 +33,27 @@ function parallel(callable $callable): callable {
         throw new \Error('Unsupported callable: ' . $e->getMessage());
     }
 
-    return function (...$args) use ($payload): Promise {
+    return function (...$args) use ($pool, $payload): Promise {
-        return enqueue(new ParallelTask($payload, $args));
+        $task = new ParallelTask($payload, $args);
+        return $pool ? $pool->enqueue($task) : enqueue($task);
     };
 }
 
 /**
  * Parallel version of array_map, but with an argument order consistent with the filter function.
  *
- * @param array    $array
+ * @param array     $array
- * @param callable $callable
+ * @param callable  $callable
+ * @param Pool|null $pool Worker pool instance to use or null to use the global pool.
  *
  * @return Promise Resolves to the result once the operation finished.
  * @throws \Error If the passed callable is not safely serializable.
  */
-function parallelMap(array $array, callable $callable): Promise {
+function parallelMap(array $array, callable $callable, Pool $pool = null): Promise {
-    return call(function () use ($array, $callable) {
+    return call(function () use ($array, $callable, $pool) {
         // Amp\Promise\any() guarantees that all operations finished prior to resolving. Amp\Promise\all() doesn't.
         // Additionally, we return all errors as a MultiReasonException instead of throwing on the first error.
-        list($errors, $results) = yield any(\array_map(parallel($callable), $array));
+        list($errors, $results) = yield any(\array_map(parallel($callable, $pool), $array));
 
         if ($errors) {
             throw new MultiReasonException($errors);
@@ -62,15 +66,16 @@ function parallelMap(array $array, callable $callable): Promise {
 /**
  * Parallel version of array_filter.
  *
- * @param array    $array
+ * @param array     $array
- * @param callable $callable
+ * @param callable  $callable
- * @param int      $flag
+ * @param int       $flag
+ * @param Pool|null $pool Worker pool instance to use or null to use the global pool.
  *
  * @return Promise
  * @throws \Error If the passed callable is not safely serializable.
  */
-function parallelFilter(array $array, callable $callable = null, int $flag = 0): Promise {
+function parallelFilter(array $array, callable $callable = null, int $flag = 0, Pool $pool = null): Promise {
-    return call(function () use ($array, $callable, $flag) {
+    return call(function () use ($array, $callable, $flag, $pool) {
         if ($callable === null) {
             if ($flag === \ARRAY_FILTER_USE_BOTH || $flag === \ARRAY_FILTER_USE_KEY) {
                 throw new \Error('A valid $callable must be provided if $flag is set.');
@@ -84,11 +89,11 @@ function parallelFilter(array $array, callable $callable = null, int $flag = 0):
         // Amp\Promise\any() guarantees that all operations finished prior to resolving. Amp\Promise\all() doesn't.
         // Additionally, we return all errors as a MultiReasonException instead of throwing on the first error.
         if ($flag === \ARRAY_FILTER_USE_BOTH) {
-            list($errors, $results) = yield any(\array_map(parallel($callable), $array, \array_keys($array)));
+            list($errors, $results) = yield any(\array_map(parallel($callable, $pool), $array, \array_keys($array)));
         } elseif ($flag === \ARRAY_FILTER_USE_KEY) {
-            list($errors, $results) = yield any(\array_map(parallel($callable), \array_keys($array)));
+            list($errors, $results) = yield any(\array_map(parallel($callable, $pool), \array_keys($array)));
         } else {
-            list($errors, $results) = yield any(\array_map(parallel($callable), $array));
+            list($errors, $results) = yield any(\array_map(parallel($callable, $pool), $array));
         }
 
         if ($errors) {

test/ParallelTest.php

@@ -2,7 +2,10 @@
 
 namespace Amp\ParallelFunctions\Test;
 
+use Amp\Parallel\Worker\Pool;
 use Amp\PHPUnit\TestCase;
+use Amp\Promise;
+use Amp\Success;
 use function Amp\ParallelFunctions\parallel;
 
 class ParallelTest extends TestCase {
@@ -17,4 +20,17 @@ class ParallelTest extends TestCase {
             return 1;
         });
     }
+
+    public function testCustomPool() {
+        $mock = $this->createMock(Pool::class);
+        $mock->expects($this->once())
+            ->method("enqueue")
+            ->willReturn(new Success(1));
+
+        $callable = parallel(function () {
+            return 0;
+        }, $mock);
+
+        $this->assertSame(1, Promise\wait($callable()));
+    }
 }