From b6e704ab8efd0f22de9a6827f55a15a5e0e516d3 Mon Sep 17 00:00:00 2001
From: Cees-Jan Kiewiet <ceesjank@gmail.com>
Date: Mon, 5 Apr 2021 12:58:37 +0200
Subject: [PATCH] Global event-loop accessor part four

---
 README.md                              | 36 ++++++++++++---
 examples/01-timers.php                 | 10 ++--
 examples/02-periodic.php               | 12 ++---
 examples/03-ticks.php                  | 10 ++--
 examples/04-signals.php                | 10 ++--
 examples/11-consume-stdin.php          | 10 ++--
 examples/12-generate-yes.php           | 10 ++--
 examples/13-http-client-blocking.php   | 10 ++--
 examples/14-http-client-async.php      | 17 ++++---
 examples/21-http-server.php            | 14 +++---
 examples/91-benchmark-ticks.php        |  8 ++--
 examples/92-benchmark-timers.php       |  8 ++--
 examples/93-benchmark-ticks-delay.php  | 10 ++--
 examples/94-benchmark-timers-delay.php | 10 ++--
 examples/95-benchmark-memory.php       | 23 ++++-----
 src/Factory.php                        | 31 +++++++++++--
 src/Loop.php                           | 50 ++++++++++++++++++++
 tests/LoopTest.php                     | 64 ++++++++++++++++++++++++++
 18 files changed, 246 insertions(+), 97 deletions(-)
 create mode 100644 src/Loop.php
 create mode 100644 tests/LoopTest.php

diff --git a/README.md b/README.md
index cdff1c88..402309b1 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,8 @@ single [`run()`](#run) call that is controlled by the user.
 
 * [Quickstart example](#quickstart-example)
 * [Usage](#usage)
+  * [Loop](#loop)
+    * [get()](#get)
   * [Factory](#factory)
     * [create()](#create)
   * [Loop implementations](#loop-implementations)
@@ -45,32 +47,32 @@ single [`run()`](#run) call that is controlled by the user.
 Here is an async HTTP server built with just the event loop.
 
 ```php
-$loop = React\EventLoop\Factory::create();
+use React\EventLoop\Loop;
 
 $server = stream_socket_server('tcp://127.0.0.1:8080');
 stream_set_blocking($server, false);
 
-$loop->addReadStream($server, function ($server) use ($loop) {
+Loop::get()->addReadStream($server, function ($server) {
     $conn = stream_socket_accept($server);
     $data = "HTTP/1.1 200 OK\r\nContent-Length: 3\r\n\r\nHi\n";
-    $loop->addWriteStream($conn, function ($conn) use (&$data, $loop) {
+    Loop::get()->addWriteStream($conn, function ($conn) use (&$data) {
         $written = fwrite($conn, $data);
         if ($written === strlen($data)) {
             fclose($conn);
-            $loop->removeWriteStream($conn);
+            Loop::get()->removeWriteStream($conn);
         } else {
             $data = substr($data, $written);
         }
     });
 });
 
-$loop->addPeriodicTimer(5, function () {
+Loop::get()->addPeriodicTimer(5, function () {
     $memory = memory_get_usage() / 1024;
     $formatted = number_format($memory, 3).'K';
     echo "Current memory usage: {$formatted}\n";
 });
 
-$loop->run();
+Loop::get()->run();
 ```
 
 See also the [examples](examples).
@@ -110,6 +112,28 @@ $loop->run();
    purposes.
 3. The loop is run with a single [`$loop->run()`](#run) call at the end of the program.
 
+### Loop
+
+The `Loop` class exists as a convenient global accessor for the event loop.
+
+#### get()
+
+The `get(): LoopInterface` method is the preferred way to get and use the event loop. With 
+it there is no need to always pass the loop around anymore. 
+
+```php
+use React\EventLoop\Loop;
+
+Loop::get()->addTimer(0.02, function () {
+    echo 'World!';
+});
+Loop::get()->addTimer(0.01, function () {
+    echo 'Hello ';
+});
+
+Loop::get()->run();
+```
+
 ### Factory
 
 The `Factory` class exists as a convenient way to pick the best available
diff --git a/examples/01-timers.php b/examples/01-timers.php
index e6107e46..5be2f3e2 100644
--- a/examples/01-timers.php
+++ b/examples/01-timers.php
@@ -1,15 +1,15 @@
 <?php
 
-require __DIR__ . '/../vendor/autoload.php';
+use React\EventLoop\Loop;
 
-$loop = React\EventLoop\Factory::create();
+require __DIR__ . '/../vendor/autoload.php';
 
-$loop->addTimer(0.8, function () {
+Loop::get()->addTimer(0.8, function () {
     echo 'world!' . PHP_EOL;
 });
 
-$loop->addTimer(0.3, function () {
+Loop::get()->addTimer(0.3, function () {
     echo 'hello ';
 });
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/02-periodic.php b/examples/02-periodic.php
index 5e138a62..6f549055 100644
--- a/examples/02-periodic.php
+++ b/examples/02-periodic.php
@@ -1,16 +1,16 @@
 <?php
 
-require __DIR__ . '/../vendor/autoload.php';
+use React\EventLoop\Loop;
 
-$loop = React\EventLoop\Factory::create();
+require __DIR__ . '/../vendor/autoload.php';
 
-$timer = $loop->addPeriodicTimer(0.1, function () {
+$timer = Loop::get()->addPeriodicTimer(0.1, function () {
     echo 'tick!' . PHP_EOL;
 });
 
-$loop->addTimer(1.0, function () use ($loop, $timer) {
-    $loop->cancelTimer($timer);
+Loop::get()->addTimer(1.0, function () use ($timer) {
+    Loop::get()->cancelTimer($timer);
     echo 'Done' . PHP_EOL;
 });
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/03-ticks.php b/examples/03-ticks.php
index 3f36c6d4..0eee59bd 100644
--- a/examples/03-ticks.php
+++ b/examples/03-ticks.php
@@ -1,15 +1,15 @@
 <?php
 
-require __DIR__ . '/../vendor/autoload.php';
+use React\EventLoop\Loop;
 
-$loop = React\EventLoop\Factory::create();
+require __DIR__ . '/../vendor/autoload.php';
 
-$loop->futureTick(function () {
+Loop::get()->futureTick(function () {
     echo 'b';
 });
-$loop->futureTick(function () {
+Loop::get()->futureTick(function () {
     echo 'c';
 });
 echo 'a';
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/04-signals.php b/examples/04-signals.php
index 90b68989..dc7e0293 100644
--- a/examples/04-signals.php
+++ b/examples/04-signals.php
@@ -1,5 +1,7 @@
 <?php
 
+use React\EventLoop\Loop;
+
 require __DIR__ . '/../vendor/autoload.php';
 
 if (!defined('SIGINT')) {
@@ -7,13 +9,11 @@
     exit(1);
 }
 
-$loop = React\EventLoop\Factory::create();
-
-$loop->addSignal(SIGINT, $func = function ($signal) use ($loop, &$func) {
+Loop::get()->addSignal(SIGINT, $func = function ($signal) use (&$func) {
     echo 'Signal: ', (string)$signal, PHP_EOL;
-    $loop->removeSignal(SIGINT, $func);
+    Loop::get()->removeSignal(SIGINT, $func);
 });
 
 echo 'Listening for SIGINT. Use "kill -SIGINT ' . getmypid() . '" or CTRL+C' . PHP_EOL;
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/11-consume-stdin.php b/examples/11-consume-stdin.php
index 2a772455..146a55eb 100644
--- a/examples/11-consume-stdin.php
+++ b/examples/11-consume-stdin.php
@@ -1,6 +1,6 @@
 <?php
 
-use React\EventLoop\Factory;
+use React\EventLoop\Loop;
 
 require __DIR__ . '/../vendor/autoload.php';
 
@@ -9,16 +9,14 @@
     exit(1);
 }
 
-$loop = Factory::create();
-
 // read everything from STDIN and report number of bytes
 // for illustration purposes only, should use react/stream instead
-$loop->addReadStream(STDIN, function ($stream) use ($loop) {
+Loop::get()->addReadStream(STDIN, function ($stream) {
     $chunk = fread($stream, 64 * 1024);
 
     // reading nothing means we reached EOF
     if ($chunk === '') {
-        $loop->removeReadStream($stream);
+        Loop::get()->removeReadStream($stream);
         stream_set_blocking($stream, true);
         fclose($stream);
         return;
@@ -27,4 +25,4 @@
     echo strlen($chunk) . ' bytes' . PHP_EOL;
 });
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/12-generate-yes.php b/examples/12-generate-yes.php
index ebc2beb4..b0da7c60 100644
--- a/examples/12-generate-yes.php
+++ b/examples/12-generate-yes.php
@@ -1,5 +1,7 @@
 <?php
 
+use React\EventLoop\Loop;
+
 require __DIR__ . '/../vendor/autoload.php';
 
 // data can be given as first argument or defaults to "y"
@@ -8,8 +10,6 @@
 // repeat data X times in order to fill around 200 KB
 $data = str_repeat($data, round(200000 / strlen($data)));
 
-$loop = React\EventLoop\Factory::create();
-
 if (!defined('STDOUT') || stream_set_blocking(STDOUT, false) !== true) {
     fwrite(STDERR, 'ERROR: Unable to set STDOUT non-blocking (not CLI or Windows?)' . PHP_EOL);
     exit(1);
@@ -17,13 +17,13 @@
 
 // write data to STDOUT whenever its write buffer accepts data
 // for illustrations purpose only, should use react/stream instead
-$loop->addWriteStream(STDOUT, function ($stdout) use ($loop, &$data) {
+Loop::get()->addWriteStream(STDOUT, function ($stdout) use (&$data) {
     // try to write data
     $r = fwrite($stdout, $data);
 
     // nothing could be written despite being writable => closed
     if ($r === 0) {
-        $loop->removeWriteStream($stdout);
+        Loop::get()->removeWriteStream($stdout);
         fclose($stdout);
         stream_set_blocking($stdout, true);
         fwrite(STDERR, 'Stopped because STDOUT closed' . PHP_EOL);
@@ -38,4 +38,4 @@
     }
 });
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/13-http-client-blocking.php b/examples/13-http-client-blocking.php
index a2dde55c..eb34b24d 100644
--- a/examples/13-http-client-blocking.php
+++ b/examples/13-http-client-blocking.php
@@ -1,11 +1,9 @@
 <?php
 
-use React\EventLoop\Factory;
+use React\EventLoop\Loop;
 
 require __DIR__ . '/../vendor/autoload.php';
 
-$loop = Factory::create();
-
 // connect to www.google.com:80 (blocking call!)
 // for illustration purposes only, should use react/socket instead
 $stream = stream_socket_client('tcp://www.google.com:80');
@@ -18,13 +16,13 @@
 fwrite($stream, "GET / HTTP/1.1\r\nHost: www.google.com\r\nConnection: close\r\n\r\n");
 
 // wait for HTTP response
-$loop->addReadStream($stream, function ($stream) use ($loop) {
+Loop::get()->addReadStream($stream, function ($stream) {
     $chunk = fread($stream, 64 * 1024);
 
     // reading nothing means we reached EOF
     if ($chunk === '') {
         echo '[END]' . PHP_EOL;
-        $loop->removeReadStream($stream);
+        Loop::get()->removeReadStream($stream);
         fclose($stream);
         return;
     }
@@ -32,4 +30,4 @@
     echo $chunk;
 });
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/14-http-client-async.php b/examples/14-http-client-async.php
index c82c9887..2e3e7e35 100644
--- a/examples/14-http-client-async.php
+++ b/examples/14-http-client-async.php
@@ -1,11 +1,10 @@
 <?php
 
 use React\EventLoop\Factory;
+use React\EventLoop\Loop;
 
 require __DIR__ . '/../vendor/autoload.php';
 
-$loop = Factory::create();
-
 // resolve hostname before establishing TCP/IP connection (resolving DNS is still blocking here)
 // for illustration purposes only, should use react/socket or react/dns instead!
 $ip = gethostbyname('www.google.com');
@@ -24,14 +23,14 @@
 
 // print progress every 10ms
 echo 'Connecting';
-$timer = $loop->addPeriodicTimer(0.01, function () {
+$timer = Loop::get()->addPeriodicTimer(0.01, function () {
     echo '.';
 });
 
 // wait for connection success/error
-$loop->addWriteStream($stream, function ($stream) use ($loop, $timer) {
-    $loop->removeWriteStream($stream);
-    $loop->cancelTimer($timer);
+Loop::get()->addWriteStream($stream, function ($stream) use ($timer) {
+    Loop::get()->removeWriteStream($stream);
+    Loop::get()->cancelTimer($timer);
 
     // check for socket error (connection rejected)
     if (stream_socket_get_name($stream, true) === false) {
@@ -45,13 +44,13 @@
     fwrite($stream, "GET / HTTP/1.1\r\nHost: www.google.com\r\nConnection: close\r\n\r\n");
 
     // wait for HTTP response
-    $loop->addReadStream($stream, function ($stream) use ($loop) {
+    Loop::get()->addReadStream($stream, function ($stream) {
         $chunk = fread($stream, 64 * 1024);
 
         // reading nothing means we reached EOF
         if ($chunk === '') {
             echo '[END]' . PHP_EOL;
-            $loop->removeReadStream($stream);
+            Loop::get()->removeReadStream($stream);
             fclose($stream);
             return;
         }
@@ -60,4 +59,4 @@
     });
 });
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/21-http-server.php b/examples/21-http-server.php
index 89520cec..4e238158 100644
--- a/examples/21-http-server.php
+++ b/examples/21-http-server.php
@@ -1,8 +1,8 @@
 <?php
 
-require __DIR__ . '/../vendor/autoload.php';
+use React\EventLoop\Loop;
 
-$loop = React\EventLoop\Factory::create();
+require __DIR__ . '/../vendor/autoload.php';
 
 // start TCP/IP server on localhost:8080
 // for illustration purposes only, should use react/socket instead
@@ -13,24 +13,24 @@
 stream_set_blocking($server, false);
 
 // wait for incoming connections on server socket
-$loop->addReadStream($server, function ($server) use ($loop) {
+Loop::get()->addReadStream($server, function ($server) {
     $conn = stream_socket_accept($server);
     $data = "HTTP/1.1 200 OK\r\nContent-Length: 3\r\n\r\nHi\n";
-    $loop->addWriteStream($conn, function ($conn) use (&$data, $loop) {
+    Loop::get()->addWriteStream($conn, function ($conn) use (&$data) {
         $written = fwrite($conn, $data);
         if ($written === strlen($data)) {
             fclose($conn);
-            $loop->removeWriteStream($conn);
+            Loop::get()->removeWriteStream($conn);
         } else {
             $data = substr($data, $written);
         }
     });
 });
 
-$loop->addPeriodicTimer(5, function () {
+Loop::get()->addPeriodicTimer(5, function () {
     $memory = memory_get_usage() / 1024;
     $formatted = number_format($memory, 3).'K';
     echo "Current memory usage: {$formatted}\n";
 });
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/91-benchmark-ticks.php b/examples/91-benchmark-ticks.php
index 3f4690b3..8a768568 100644
--- a/examples/91-benchmark-ticks.php
+++ b/examples/91-benchmark-ticks.php
@@ -1,15 +1,13 @@
 <?php
 
-use React\EventLoop\Factory;
+use React\EventLoop\Loop;
 
 require __DIR__ . '/../vendor/autoload.php';
 
-$loop = Factory::create();
-
 $n = isset($argv[1]) ? (int)$argv[1] : 1000 * 100;
 
 for ($i = 0; $i < $n; ++$i) {
-    $loop->futureTick(function () { });
+    Loop::get()->futureTick(function () { });
 }
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/92-benchmark-timers.php b/examples/92-benchmark-timers.php
index e2e02e49..51cb9596 100644
--- a/examples/92-benchmark-timers.php
+++ b/examples/92-benchmark-timers.php
@@ -1,15 +1,13 @@
 <?php
 
-use React\EventLoop\Factory;
+use React\EventLoop\Loop;
 
 require __DIR__ . '/../vendor/autoload.php';
 
-$loop = Factory::create();
-
 $n = isset($argv[1]) ? (int)$argv[1] : 1000 * 100;
 
 for ($i = 0; $i < $n; ++$i) {
-    $loop->addTimer(0, function () { });
+    Loop::get()->addTimer(0, function () { });
 }
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/93-benchmark-ticks-delay.php b/examples/93-benchmark-ticks-delay.php
index 95ee78c6..b37cfbc2 100644
--- a/examples/93-benchmark-ticks-delay.php
+++ b/examples/93-benchmark-ticks-delay.php
@@ -1,17 +1,15 @@
 <?php
 
-use React\EventLoop\Factory;
+use React\EventLoop\Loop;
 
 require __DIR__ . '/../vendor/autoload.php';
 
-$loop = Factory::create();
-
 $ticks = isset($argv[1]) ? (int)$argv[1] : 1000 * 100;
-$tick = function () use (&$tick, &$ticks, $loop) {
+$tick = function () use (&$tick, &$ticks) {
     if ($ticks > 0) {
         --$ticks;
         //$loop->addTimer(0, $tick);
-        $loop->futureTick($tick);
+        Loop::get()->futureTick($tick);
     } else {
         echo 'done';
     }
@@ -19,4 +17,4 @@
 
 $tick();
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/94-benchmark-timers-delay.php b/examples/94-benchmark-timers-delay.php
index 2d6cfa25..e8e380a2 100644
--- a/examples/94-benchmark-timers-delay.php
+++ b/examples/94-benchmark-timers-delay.php
@@ -1,17 +1,15 @@
 <?php
 
-use React\EventLoop\Factory;
+use React\EventLoop\Loop;
 
 require __DIR__ . '/../vendor/autoload.php';
 
-$loop = Factory::create();
-
 $ticks = isset($argv[1]) ? (int)$argv[1] : 1000 * 100;
-$tick = function () use (&$tick, &$ticks, $loop) {
+$tick = function () use (&$tick, &$ticks) {
     if ($ticks > 0) {
         --$ticks;
         //$loop->futureTick($tick);
-        $loop->addTimer(0, $tick);
+        Loop::get()->addTimer(0, $tick);
     } else {
         echo 'done';
     }
@@ -19,4 +17,4 @@
 
 $tick();
 
-$loop->run();
+Loop::get()->run();
diff --git a/examples/95-benchmark-memory.php b/examples/95-benchmark-memory.php
index 084c4042..14d77872 100644
--- a/examples/95-benchmark-memory.php
+++ b/examples/95-benchmark-memory.php
@@ -8,6 +8,7 @@
  */
 
 use React\EventLoop\Factory;
+use React\EventLoop\Loop;
 use React\EventLoop\LoopInterface;
 use React\EventLoop\TimerInterface;
 
@@ -15,10 +16,10 @@
 
 $args = getopt('t:l:r:');
 $t  = isset($args['t']) ? (int)$args['t'] : 0;
-$loop = isset($args['l']) && class_exists('React\EventLoop\\' . $args['l'] . 'Loop') ? 'React\EventLoop\\' . $args['l'] . 'Loop' : Factory::create();
+$loop = isset($args['l']) && class_exists('React\EventLoop\\' . $args['l'] . 'Loop') ? 'React\EventLoop\\' . $args['l'] . 'Loop' : Loop::get();
 
 if (!($loop instanceof LoopInterface)) {
-    $loop = new $loop();
+    Loop::set(new $loop());
 }
 
 $r = isset($args['r']) ? (int)$args['r'] : 2;
@@ -26,21 +27,21 @@
 $runs = 0;
 
 if (5 < $t) {
-    $loop->addTimer($t, function () use ($loop) {
-        $loop->stop();
+    Loop::get()->addTimer($t, function () {
+        Loop::get()->stop();
     });
 
 }
 
-$loop->addPeriodicTimer(0.001, function () use (&$runs, $loop) {
+Loop::get()->addPeriodicTimer(0.001, function () use (&$runs) {
     $runs++;
 
-    $loop->addPeriodicTimer(1, function (TimerInterface $timer) use ($loop) {
-        $loop->cancelTimer($timer);
+    Loop::get()->addPeriodicTimer(1, function (TimerInterface $timer) {
+        Loop::get()->cancelTimer($timer);
     });
 });
 
-$loop->addPeriodicTimer($r, function () use (&$runs) {
+Loop::get()->addPeriodicTimer($r, function () use (&$runs) {
     $kmem = round(memory_get_usage() / 1024);
     $kmemReal = round(memory_get_usage(true) / 1024);
     echo "Runs:\t\t\t$runs\n";
@@ -50,18 +51,18 @@
 });
 
 echo "PHP Version:\t\t", phpversion(), "\n";
-echo "Loop\t\t\t", get_class($loop), "\n";
+echo "Loop\t\t\t", get_class(Loop::get()), "\n";
 echo "Time\t\t\t", date('r'), "\n";
 
 echo str_repeat('-', 50), "\n";
 
 $beginTime = time();
-$loop->run();
+Loop::get()->run();
 $endTime = time();
 $timeTaken = $endTime - $beginTime;
 
 echo "PHP Version:\t\t", phpversion(), "\n";
-echo "Loop\t\t\t", get_class($loop), "\n";
+echo "Loop\t\t\t", get_class(Loop::get()), "\n";
 echo "Time\t\t\t", date('r'), "\n";
 echo "Time taken\t\t", $timeTaken, " seconds\n";
 echo "Runs per second\t\t", round($runs / $timeTaken), "\n";
diff --git a/src/Factory.php b/src/Factory.php
index d1767bf8..1843d86e 100644
--- a/src/Factory.php
+++ b/src/Factory.php
@@ -19,21 +19,44 @@ final class Factory
      *
      * This method should usually only be called once at the beginning of the program.
      *
+     * @deprecated Use Loop::get instead
+     *
      * @return LoopInterface
      */
     public static function create()
+    {
+        $loop = self::construct();
+
+        Loop::set($loop);
+
+        return $loop;
+    }
+
+    /**
+     * @internal
+     * @return LoopInterface
+     */
+    private static function construct()
     {
         // @codeCoverageIgnoreStart
         if (\function_exists('uv_loop_new')) {
             // only use ext-uv on PHP 7
             return new ExtUvLoop();
-        } elseif (\class_exists('libev\EventLoop', false)) {
+        }
+
+        if (\class_exists('libev\EventLoop', false)) {
             return new ExtLibevLoop();
-        } elseif (\class_exists('EvLoop', false)) {
+        }
+
+        if (\class_exists('EvLoop', false)) {
             return new ExtEvLoop();
-        } elseif (\class_exists('EventBase', false)) {
+        }
+
+        if (\class_exists('EventBase', false)) {
             return new ExtEventLoop();
-        } elseif (\function_exists('event_base_new') && \PHP_MAJOR_VERSION === 5) {
+        }
+
+        if (\function_exists('event_base_new') && \PHP_MAJOR_VERSION === 5) {
             // only use ext-libevent on PHP 5 for now
             return new ExtLibeventLoop();
         }
diff --git a/src/Loop.php b/src/Loop.php
new file mode 100644
index 00000000..e91291e3
--- /dev/null
+++ b/src/Loop.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace React\EventLoop;
+
+/**
+ * The `Loop` class exists as a convenient way to get the currently relevant loop
+ */
+final class Loop
+{
+    /**
+     * @var LoopInterface
+     */
+    private static $instance;
+
+
+    /**
+     * Returns the event loop.
+     * When no loop is set it will it will call the factory to create one.
+     *
+     * This method always returns an instance implementing `LoopInterface`,
+     * the actual event loop implementation is an implementation detail.
+     *
+     * This method is the preferred way to get the event loop and using
+     * Factory::create has been deprecated.
+     *
+     * @return LoopInterface
+     */
+    public static function get()
+    {
+        if (self::$instance instanceof LoopInterface) {
+            return self::$instance;
+        }
+
+        self::$instance = Factory::create();
+
+        return self::$instance;
+    }
+
+    /**
+     * Internal undocumented method, behavior might change or throw in the
+     * future. Use with cation and at your own risk.
+     *
+     * @internal
+     * @return void
+     */
+    public static function set(LoopInterface $loop)
+    {
+        self::$instance = $loop;
+    }
+}
diff --git a/tests/LoopTest.php b/tests/LoopTest.php
new file mode 100644
index 00000000..a653035a
--- /dev/null
+++ b/tests/LoopTest.php
@@ -0,0 +1,64 @@
+<?php
+
+namespace React\Tests\EventLoop;
+
+use React\EventLoop\Factory;
+use React\EventLoop\Loop;
+use ReflectionClass;
+
+final class LoopTest extends TestCase
+{
+    /**
+     * @dataProvider numberOfTests
+     */
+    public function testFactoryCreateSetsEventLoopOnLoopAccessor()
+    {
+        $factoryLoop = Factory::create();
+        $accessorLoop = Loop::get();
+
+        self::assertSame($factoryLoop, $accessorLoop);
+    }
+
+    /**
+     * @dataProvider numberOfTests
+     */
+    public function testCallingFactoryAfterCallingLoopGetYieldsADifferentInstanceOfTheEventLoop()
+    {
+        // Note that this behavior isn't wise and highly advised against. Always used Loop::get.
+        $accessorLoop = Loop::get();
+        $factoryLoop = Factory::create();
+
+        self::assertNotSame($factoryLoop, $accessorLoop);
+    }
+
+    /**
+     * @dataProvider numberOfTests
+     */
+    public function testCallingLoopGetShouldAlwaysReturnTheSameEventLoop()
+    {
+        self::assertSame(Loop::get(), Loop::get());
+    }
+
+    /**
+     * Run several tests several times to ensure we reset the loop between tests and code is still behavior as expected.
+     *
+     * @return array<array>
+     */
+    public function numberOfTests()
+    {
+        return array(array(), array(), array());
+    }
+
+    /**
+     * @after
+     * @before
+     */
+    public function unsetLoopFromLoopAccessor()
+    {
+        $ref = new ReflectionClass('\React\EventLoop\Loop');
+        $prop = $ref->getProperty('instance');
+        $prop->setAccessible(true);
+        $prop->setValue(null);
+        $prop->setAccessible(false);
+    }
+}