Add OpenTelemetry events for PeerConnection state changes / errors

Creates a new class to represent individual calls and adds the listeners
there.

Requires https://github.com/matrix-org/matrix-js-sdk/pull/3251
Based on https://github.com/vector-im/element-call/pull/974

src/otel/OTelCall.ts

@@ -0,0 +1,103 @@
+/*
+Copyright 2023 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { Span } from "@opentelemetry/api";
+import { MatrixCall } from "matrix-js-sdk";
+import { CallEvent } from "matrix-js-sdk/src/webrtc/call";
+
+import { ObjectFlattener } from "./ObjectFlattener";
+
+/**
+ * Tracks an individual call within a group call, either to a full-mesh peer or a focus
+ */
+export class OTelCall {
+  constructor(
+    public userId: string,
+    public deviceId: string,
+    public call: MatrixCall,
+    public span: Span
+  ) {
+    if (call.peerConn) {
+      this.addCallPeerConnListeners();
+    } else {
+      this.call.once(
+        CallEvent.PeerConnectionCreated,
+        this.addCallPeerConnListeners
+      );
+    }
+  }
+
+  public dispose() {
+    this.call.peerConn.removeEventListener(
+      "iceconnectionstatechange",
+      this.onIceConnectionStateChanged
+    );
+  }
+
+  private addCallPeerConnListeners = (): void => {
+    this.call.peerConn.addEventListener(
+      "connectionstatechange",
+      this.onCallConnectionStateChanged
+    );
+    this.call.peerConn.addEventListener(
+      "signalingstatechange",
+      this.onCallSignalingStateChanged
+    );
+    this.call.peerConn.addEventListener(
+      "iceconnectionstatechange",
+      this.onIceConnectionStateChanged
+    );
+    this.call.peerConn.addEventListener(
+      "icegatheringstatechange",
+      this.onIceGatheringStateChanged
+    );
+    this.call.peerConn.addEventListener(
+      "icecandidateerror",
+      this.onIceCandidateError
+    );
+  };
+
+  public onCallConnectionStateChanged = (): void => {
+    this.span.addEvent("matrix.call.callConnectionStateChange", {
+      callConnectionState: this.call.peerConn.connectionState,
+    });
+  };
+
+  public onCallSignalingStateChanged = (): void => {
+    this.span.addEvent("matrix.call.callSignalingStateChange", {
+      callSignalingState: this.call.peerConn.signalingState,
+    });
+  };
+
+  public onIceConnectionStateChanged = (): void => {
+    this.span.addEvent("matrix.call.iceConnectionStateChange", {
+      iceConnectionState: this.call.peerConn.iceConnectionState,
+    });
+  };
+
+  public onIceGatheringStateChanged = (): void => {
+    this.span.addEvent("matrix.call.iceGatheringStateChange", {
+      iceGatheringState: this.call.peerConn.iceGatheringState,
+    });
+  };
+
+  public onIceCandidateError = (ev: Event): void => {
+    const flatObject = {};
+    ObjectFlattener.flattenObjectRecursive(ev, flatObject, "error.", 0);
+
+    this.span.addEvent("matrix.call.iceCandidateError", flatObject);
+  };
+}

src/otel/OTelGroupCallMembership.ts

@@ -43,6 +43,7 @@ import { setSpan } from "@opentelemetry/api/build/esm/trace/context-utils";
 
 import { ElementCallOpenTelemetry } from "./otel";
 import { ObjectFlattener } from "./ObjectFlattener";
+import { OTelCall } from "./OTelCall";
 
 /**
  * Flattens out an object into a single layer with components
@@ -86,13 +87,6 @@ function flattenVoipEventRecursive(
   }
 }
 
-interface CallTrackingInfo {
-  userId: string;
-  deviceId: string;
-  call: MatrixCall;
-  span: Span;
-}
-
 /**
  * Represent the span of time which we intend to be joined to a group call
  */
@@ -102,7 +96,7 @@ export class OTelGroupCallMembership {
   private myUserId = "unknown";
   private myDeviceId: string;
   private myMember?: RoomMember;
-  private callsByCallId = new Map<string, CallTrackingInfo>();
+  private callsByCallId = new Map<string, OTelCall>();
   private statsReportSpan: {
     span: Span | undefined;
     stats: OTelStatsReportEvent[];
@@ -188,12 +182,10 @@ export class OTelGroupCallMembership {
           // XXX: anonymity
           span.setAttribute("matrix.call.target.userId", userId);
           span.setAttribute("matrix.call.target.deviceId", deviceId);
-          this.callsByCallId.set(call.callId, {
-            userId,
-            deviceId,
-            call,
-            span,
-          });
+          this.callsByCallId.set(
+            call.callId,
+            new OTelCall(userId, deviceId, call, span)
+          );
         }
       }
     }