From adac0c353cab2faa78b2c0c51e066935583382a7 Mon Sep 17 00:00:00 2001
From: David Baker <dave@matrix.org>
Date: Fri, 22 Nov 2019 15:56:06 +0000
Subject: [PATCH 1/2] Fix calls in e2e rooms

Events will be decrypted after the sync event, so we were having
to wait until the next sync event before they got processed.
---
 src/client.js | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/src/client.js b/src/client.js
index 2a7654bfc..5803e6807 100644
--- a/src/client.js
+++ b/src/client.js
@@ -4644,8 +4644,11 @@ function setupCallEventHandler(client) {
     // This happens quite often, eg. replaying sync from storage, catchup sync
     // after loading and after we've been offline for a bit.
     let callEventBuffer = [];
-    function onSync(state) {
-        if (state === "SYNCING") {
+    function evaluateEventBuffer() {
+        if (client.getSyncState() === "SYNCING") {
+            // don't process any events until they are all decrypted
+            if (callEventBuffer.some((e) => e.isBeingDecrypted())) return;
+
             const ignoreCallIds = {}; // Set<String>
             // inspect the buffer and mark all calls which have been answered
             // or hung up before passing them to the call event handler.
@@ -4670,20 +4673,31 @@ function setupCallEventHandler(client) {
             callEventBuffer = [];
         }
     }
-    client.on("sync", onSync);
+    client.on("sync", evaluateEventBuffer);
 
     function onEvent(event) {
-        if (event.getType().indexOf("m.call.") !== 0) {
-            // not a call event
-            if (event.isBeingDecrypted() || event.isDecryptionFailure()) {
-                // not *yet* a call event, but might become one...
-                event.once("Event.decrypted", onEvent);
-            }
-            return;
+        // any call events or ones that might be once they're decrypted
+        if (event.getType().indexOf("m.call.") === 0 || event.isBeingDecrypted()) {
+            // queue up for processing once all events from this sync have been
+            // processed (see above).
+            callEventBuffer.push(event);
+        }
+
+        if (event.isBeingDecrypted() || event.isDecryptionFailure()) {
+            // add an event listener for once the event is decrypted.
+            event.once("Event.decrypted", () => {
+                if (event.getType().indexOf("m.call.") === -1) return;
+
+                if (callEventBuffer.includes(event)) {
+                    // we were waiting for that event to decrypt, so recheck the buffer
+                    evaluateEventBuffer();
+                } else {
+                    // This one wasn't buffered so just run the event handler for it
+                    // straight away
+                    callEventHandler(e);
+                }
+            });
         }
-        // queue up for processing once all events from this sync have been
-        // processed (see above).
-        callEventBuffer.push(event);
     }
     client.on("event", onEvent);
 

From d8337d703d61ad9300da763cf4e1f2a579366828 Mon Sep 17 00:00:00 2001
From: David Baker <dave@matrix.org>
Date: Fri, 22 Nov 2019 15:59:36 +0000
Subject: [PATCH 2/2] Use the right variable name

---
 src/client.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/client.js b/src/client.js
index 5803e6807..c62c8fca0 100644
--- a/src/client.js
+++ b/src/client.js
@@ -4694,7 +4694,7 @@ function setupCallEventHandler(client) {
                 } else {
                     // This one wasn't buffered so just run the event handler for it
                     // straight away
-                    callEventHandler(e);
+                    callEventHandler(event);
                 }
             });
         }