Add ContextFactory

lib/Context/ContextFactory.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Amp\Parallel\Context;
+
+use Amp\Promise;
+
+interface ContextFactory
+{
+    /**
+     * Creates a new execution context.
+     *
+     * @param string|string[] $script Path to PHP script or array with first element as path and following elements options
+     *     to the PHP script (e.g.: ['bin/worker', 'Option1Value', 'Option2Value'].
+     *
+     * @return Context
+     */
+    public function create($script): Context;
+
+    /**
+     * Creates and starts a new execution context.
+     *
+     * @param string|string[] $script Path to PHP script or array with first element as path and following elements options
+     *     to the PHP script (e.g.: ['bin/worker', 'Option1Value', 'Option2Value'].
+     *
+     * @return Promise<Context>
+     */
+    public function run($script): Promise;
+}

lib/Context/DefaultContextFactory.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace Amp\Parallel\Context;
+
+use Amp\Promise;
+
+class DefaultContextFactory implements ContextFactory
+{
+    function create($script): Context
+    {
+        /**
+         * Creates a thread if ext-parallel is installed, otherwise creates a child process.
+         *
+         * @inheritdoc
+         */
+        if (Parallel::isSupported()) {
+            return new Parallel($script);
+        }
+
+        return new Process($script);
+    }
+
+    /**
+     * Creates and starts a thread if ext-parallel is installed, otherwise creates a child process.
+     *
+     * @inheritdoc
+     */
+    function run($script): Promise
+    {
+        if (Parallel::isSupported()) {
+            return Parallel::run($script);
+        }
+
+        return Process::run($script);
+    }
+}

lib/Context/functions.php

@@ -2,32 +2,53 @@
 
 namespace Amp\Parallel\Context;
 
+use Amp\Loop;
 use Amp\Promise;
 
+const LOOP_FACTORY_IDENTIFIER = ContextFactory::class;
+
 /**
- * @param string|string[] $script
+ * @param string|string[] $script Path to PHP script or array with first element as path and following elements options
+ *     to the PHP script (e.g.: ['bin/worker', 'Option1Value', 'Option2Value'].
  *
  * @return Context
  */
 function create($script): Context
 {
-    if (Parallel::isSupported()) {
-        return new Parallel($script);
-    }
-
-    return new Process($script);
+    return factory()->create($script);
 }
 
 /**
- * @param string|string[] $script
+ * Creates and starts a process based on installed extensions (a thread if ext-parallel is installed, otherwise a child
+ * process).
+ *
+ * @param string|string[] $script Path to PHP script or array with first element as path and following elements options
+ *     to the PHP script (e.g.: ['bin/worker', 'Option1Value', 'Option2Value'].
  *
  * @return Promise<Context>
  */
 function run($script): Promise
 {
-    if (Parallel::isSupported()) {
-        return Parallel::run($script);
-    }
-
-    return Process::run($script);
+    return factory()->run($script);
+}
+
+/**
+ * Gets or sets the global context factory.
+ *
+ * @param ContextFactory|null $factory
+ *
+ * @return ContextFactory
+ */
+function factory(?ContextFactory $factory = null): ContextFactory
+{
+    if ($factory === null) {
+        $factory = Loop::getState(LOOP_FACTORY_IDENTIFIER);
+        if ($factory) {
+            return $factory;
+        }
+
+        $factory = new DefaultContextFactory;
+    }
+    Loop::setState(LOOP_FACTORY_IDENTIFIER, $factory);
+    return $factory;
 }

test/Context/DefaultContextFactoryTest.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Amp\Parallel\Test\Context;
+
+use Amp\Parallel\Context\Context;
+use Amp\Parallel\Context\DefaultContextFactory;
+use Amp\Parallel\Sync\ContextPanicError;
+use Amp\PHPUnit\AsyncTestCase;
+
+class DefaultWorkerFactoryTest extends AsyncTestCase
+{
+    public function testCreate(): void
+    {
+        $factory = new DefaultContextFactory;
+        $context = $factory->create(__DIR__ . '/Fixtures/test-process.php');
+        $this->assertInstanceOf(Context::class, $context);
+    }
+
+    public function testRun(): \Generator
+    {
+        $this->expectException(ContextPanicError::class);
+        $this->expectExceptionMessage('No string provided');
+
+        $factory = new DefaultContextFactory;
+        $context = yield $factory->run(__DIR__ . '/Fixtures/test-process.php');
+        yield $context->join();
+    }
+}