fix memory leak in soundfile

Do not create an event listener every time a soundfile is played. Reference the same event listener and bind to this instance of the soundfile. We use this event listener to keep track of the current time (and may want to consider deprecating that functionality because it creates complications like this!).

Same for the "clearOnEnd" event listener, which we use to remove references to the bufferSourceNodes within a single sound file when they are done playing so that they can be garbage collected. This is useful to be able to control many bufferSourceNodes from a single sound file, and do things like soundfile.stopAll(), but it adds complexity and could also be a candidate for deprecation.

Author: therewasaguy

src/soundfile.js

@@ -138,6 +138,9 @@ define(function (require) {
     } else {
       this._whileLoading = function() {};
     }
+
+    this._onAudioProcess = _onAudioProcess.bind(this);
+    this._clearOnEnd = _clearOnEnd.bind(this);
   };
 
   // register preload handling of loadSound
@@ -414,25 +417,7 @@ define(function (require) {
       this.bufferSourceNodes.push(this.bufferSourceNode);
       this.bufferSourceNode._arrayIndex = this.bufferSourceNodes.length - 1;
 
-      // delete this.bufferSourceNode from the sources array when it is done playing:
-      var clearOnEnd = function() {
-        this._playing = false;
-        this.removeEventListener('ended', clearOnEnd, false);
-        // call the onended callback
-        self._onended(self);
-
-        self.bufferSourceNodes.forEach(function(n, i) {
-          if (n._playing === false) {
-            self.bufferSourceNodes.splice(i);
-          }
-        });
-
-        if (self.bufferSourceNodes.length === 0) {
-          self._playing = false;
-        }
-      };
-
-      this.bufferSourceNode.onended = clearOnEnd;
+      this.bufferSourceNode.addEventListener('ended', this._clearOnEnd);
     }
     // If soundFile hasn't loaded the buffer yet, throw an error
     else {
@@ -674,11 +659,11 @@ define(function (require) {
     var now = p5sound.audiocontext.currentTime;
     var time = _time || 0;
     if (this.buffer && this.bufferSourceNode) {
-      for (var i = 0; i < this.bufferSourceNodes.length; i++) {
-        if (typeof this.bufferSourceNodes[i] !== undefined) {
+      for (var i in this.bufferSourceNodes) {
+        const bufferSourceNode = this.bufferSourceNodes[i];
+        if (!!bufferSourceNode) {
           try {
-            this.bufferSourceNodes[i].onended = function() {};
-            this.bufferSourceNodes[i].stop(now + time);
+            bufferSourceNode.stop(now + time);
           } catch(e) {
             // this was throwing errors only on Safari
           }
@@ -1227,7 +1212,7 @@ define(function (require) {
     // dispose of scope node if it already exists
     if (self._scopeNode) {
       self._scopeNode.disconnect();
-      delete self._scopeNode.onaudioprocess;
+      self._scopeNode.removeEventListener('audioprocess', self._onAudioProcess);
       delete self._scopeNode;
     }
     self._scopeNode = ac.createScriptProcessor( 256, 1, 1 );
@@ -1240,14 +1225,7 @@ define(function (require) {
     cNode.connect( self._scopeNode );
     self._scopeNode.connect( p5.soundOut._silentNode );
 
-    self._scopeNode.onaudioprocess = function(processEvent) {
-      var inputBuffer = processEvent.inputBuffer.getChannelData( 0 );
-
-      self._lastPos = inputBuffer[ inputBuffer.length - 1 ] || 0;
-
-      // do any callbacks that have been scheduled
-      self._onTimeUpdate(self._lastPos);
-    };
+    self._scopeNode.addEventListener('audioprocess', self._onAudioProcess);
 
     return cNode;
   };
@@ -1735,4 +1713,36 @@ define(function (require) {
     return new Blob([dataView], { type: 'audio/wav' });
   };
 
+  // event handler to keep track of current position
+  function _onAudioProcess(processEvent) {
+    var inputBuffer = processEvent.inputBuffer.getChannelData(0);
+
+    this._lastPos = inputBuffer[inputBuffer.length - 1] || 0;
+
+    // do any callbacks that have been scheduled
+    this._onTimeUpdate(self._lastPos);
+  }
+
+  // event handler to remove references to the bufferSourceNode when it is done playing
+  function _clearOnEnd(e) {
+    const thisBufferSourceNode = e.target;
+    const soundFile = this;
+
+    // delete this.bufferSourceNode from the sources array when it is done playing:
+    thisBufferSourceNode._playing = false;
+    thisBufferSourceNode.removeEventListener('ended', soundFile._clearOnEnd);
+
+    // call the onended callback
+    soundFile._onended(soundFile);
+
+    soundFile.bufferSourceNodes.forEach(function (n, i) {
+      if (n._playing === false) {
+        soundFile.bufferSourceNodes.splice(i);
+      }
+    });
+
+    if (soundFile.bufferSourceNodes.length === 0) {
+      soundFile._playing = false;
+    }
+  }
 });