From 1cc74ec116e8299a64832ba8563e428a08b47cf1 Mon Sep 17 00:00:00 2001
From: Matthew Hodgson <matthew@matrix.org>
Date: Wed, 31 Aug 2016 20:57:08 +0100
Subject: [PATCH] don't break the promise chain if a play() fails

---
 lib/webrtc/call.js | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/lib/webrtc/call.js b/lib/webrtc/call.js
index b42ba3c0d..024bdc616 100644
--- a/lib/webrtc/call.js
+++ b/lib/webrtc/call.js
@@ -157,11 +157,21 @@ MatrixCall.prototype.placeScreenSharingCall =
  * @param {string} queueId Arbitrary ID to track the chain of promises to be used
  */
 MatrixCall.prototype.playElement = function(element, queueId) {
+    console.log("queuing play on " + queueId + " and element " + element);
     // XXX: FIXME: Does this leak elements, given the old promises
     // may hang around and retain a reference to them?
     if (this.mediaPromises[queueId]) {
+        // XXX: these promises can fail (e.g. by <video/> being unmounted whilst
+        // pending receiving media to play - e.g. whilst switching between
+        // rooms before answering an inbound call), and throw unhandled exceptions.
+        // However, we should soldier on as best we can even if they fail, given
+        // these failures may be non-fatal (as in the case of unmounts)
         this.mediaPromises[queueId] =
             this.mediaPromises[queueId].then(function() {
+                console.log("previous promise completed for " + queueId);
+                return element.play();
+            }, function() {
+                console.log("previous promise failed for " + queueId);
                 return element.play();
             });
     }
@@ -177,9 +187,14 @@ MatrixCall.prototype.playElement = function(element, queueId) {
  * @param {string} queueId Arbitrary ID to track the chain of promises to be used
  */
 MatrixCall.prototype.pauseElement = function(element, queueId) {
+    console.log("queuing pause on " + queueId + " and element " + element);
     if (this.mediaPromises[queueId]) {
         this.mediaPromises[queueId] =
             this.mediaPromises[queueId].then(function() {
+                console.log("previous promise completed for " + queueId);
+                return element.pause();
+            }, function() {
+                console.log("previous promise failed for " + queueId);
                 return element.pause();
             });
     }
@@ -199,9 +214,14 @@ MatrixCall.prototype.pauseElement = function(element, queueId) {
  * @param {string} queueId Arbitrary ID to track the chain of promises to be used
  */
 MatrixCall.prototype.assignElement = function(element, src, queueId) {
+    console.log("queuing assign on " + queueId + " and element " + element + " for " + src);
     if (this.mediaPromises[queueId]) {
         this.mediaPromises[queueId] =
             this.mediaPromises[queueId].then(function() {
+                console.log("previous promise completed for " + queueId);
+                element.src = src;
+            }, function() {
+                console.log("previous promise failed for " + queueId);
                 element.src = src;
             });
     }