Merge pull request #171 from clue-labs/drain-throughstream

Fix `drain` event of `ThroughStream` to handle potential race condition

Author: WyriHaximus

src/ThroughStream.php

@@ -93,16 +93,19 @@ public function __construct($callback = null)
 
     public function pause()
     {
-        $this->paused = true;
+        // only allow pause if still readable, false otherwise
+        $this->paused = $this->readable;
     }
 
     public function resume()
     {
+        $this->paused = false;
+
+        // emit drain event if previous write was paused (throttled)
         if ($this->drain) {
             $this->drain = false;
             $this->emit('drain');
         }
-        $this->paused = false;
     }
 
     public function pipe(WritableStreamInterface $dest, array $options = array())
@@ -139,12 +142,13 @@ public function write($data)
 
         $this->emit('data', array($data));
 
+        // emit drain event on next resume if currently paused (throttled)
         if ($this->paused) {
             $this->drain = true;
-            return false;
         }
 
-        return true;
+        // continue writing if still writable and not paused (throttled), false otherwise
+        return $this->writable && !$this->paused;
     }
 
     public function end($data = null)
@@ -164,7 +168,7 @@ public function end($data = null)
 
         $this->readable = false;
         $this->writable = false;
-        $this->paused = true;
+        $this->paused = false;
         $this->drain = false;
 
         $this->emit('end');
@@ -179,9 +183,10 @@ public function close()
 
         $this->readable = false;
         $this->writable = false;
-        $this->closed = true;
-        $this->paused = true;
+        $this->paused = false;
         $this->drain = false;
+
+        $this->closed = true;
         $this->callback = null;
 
         $this->emit('close');

tests/ThroughStreamTest.php

@@ -95,6 +95,30 @@ public function itShouldReturnFalseForAnyDataWrittenToItWhenPaused()
         $this->assertFalse($ret);
     }
 
+    /** @test */
+    public function itShouldReturnFalseForAnyDataWrittenToItWhenDataEventEndsStream()
+    {
+        $through = new ThroughStream();
+        $through->on('data', function () use ($through) {
+            $through->end();
+        });
+        $ret = $through->write('foo');
+
+        $this->assertFalse($ret);
+    }
+
+    /** @test */
+    public function itShouldReturnFalseForAnyDataWrittenToItWhenDataEventClosesStream()
+    {
+        $through = new ThroughStream();
+        $through->on('data', function () use ($through) {
+            $through->close();
+        });
+        $ret = $through->write('foo');
+
+        $this->assertFalse($ret);
+    }
+
     /** @test */
     public function itShouldEmitDrainOnResumeAfterReturnFalseForAnyDataWrittenToItWhenPaused()
     {
@@ -106,6 +130,40 @@ public function itShouldEmitDrainOnResumeAfterReturnFalseForAnyDataWrittenToItWh
         $through->resume();
     }
 
+    /** @test */
+    public function itShouldNotEmitDrainOnResumeAfterClose()
+    {
+        $through = new ThroughStream();
+        $through->close();
+
+        $through->on('drain', $this->expectCallableNever());
+        $through->resume();
+    }
+
+    /** @test */
+    public function itShouldNotEmitDrainOnResumeAfterReturnFalseForAnyDataWrittenThatCausesStreamToClose()
+    {
+        $through = new ThroughStream();
+        $through->on('data', function () use ($through) { $through->close(); });
+        $through->write('foo');
+
+        $through->on('drain', $this->expectCallableNever());
+        $through->resume();
+    }
+
+    /** @test */
+    public function itShouldReturnFalseForAnyDataWrittenToItAfterPausingFromDrainEvent()
+    {
+        $through = new ThroughStream();
+        $through->pause();
+        $through->write('foo');
+
+        $through->on('drain', function () use ($through) { $through->pause(); });
+        $through->resume();
+
+        $this->assertFalse($through->write('bar'));
+    }
+
     /** @test */
     public function itShouldReturnTrueForAnyDataWrittenToItWhenResumedAfterPause()
     {