Add some simple functions for global worker pool

composer.json

@@ -35,7 +35,10 @@
     "autoload": {
         "psr-4": {
             "Icicle\\Concurrent\\": "src"
-        }
+        },
+        "files": [
+            "src/Worker/functions.php"
+        ]
     },
     "autoload-dev": {
         "psr-4": {

examples/worker-pool.php

@@ -2,23 +2,21 @@
 <?php
 require dirname(__DIR__).'/vendor/autoload.php';
 
+use Icicle\Concurrent\Worker;
 use Icicle\Concurrent\Worker\HelloTask;
-use Icicle\Concurrent\Worker\WorkerPool;
 use Icicle\Coroutine;
 use Icicle\Loop;
 use Icicle\Promise;
 
 Coroutine\create(function () {
-    $pool = new WorkerPool(1);
-
     $returnValues = (yield Promise\all([
-        new Coroutine\Coroutine($pool->enqueue(new HelloTask())),
-        new Coroutine\Coroutine($pool->enqueue(new HelloTask())),
-        new Coroutine\Coroutine($pool->enqueue(new HelloTask())),
+        new Coroutine\Coroutine(Worker\enqueue(new HelloTask())),
+        new Coroutine\Coroutine(Worker\enqueue(new HelloTask())),
+        new Coroutine\Coroutine(Worker\enqueue(new HelloTask())),
     ]));
     var_dump($returnValues);
 
-    yield $pool->shutdown();
+    yield Worker\pool()->shutdown();
 })->done();
 
 Loop\run();

src/Worker/functions.php

@@ -0,0 +1,40 @@
+<?php
+namespace Icicle\Concurrent\Worker;
+
+if (!function_exists(__NAMESPACE__ . '\pool')) {
+    /**
+     * Returns the default worker pool for the current context.
+     *
+     * @param WorkerPool $pool The instance to use as the default worker pool.
+     *
+     * @return WorkerPool
+     */
+    function pool(WorkerPool $pool = null)
+    {
+        static $instance;
+
+        if (null !== $pool) {
+            $instance = $pool;
+        } elseif (null === $instance) {
+            $instance = new WorkerPool(4, 16);
+        }
+
+        return $instance;
+    }
+
+    /**
+     * Enqueues a task to be executed by the worker pool.
+     *
+     * @coroutine
+     *
+     * @param TaskInterface $task The task to enqueue.
+     *
+     * @return \Generator
+     *
+     * @resolve mixed The return value of the task.
+     */
+    function enqueue(TaskInterface $task)
+    {
+        return pool()->enqueue($task);
+    }
+}