1 files changed, 135 insertions, 0 deletions
diff --git a/devtools/server/actors/resources/server-sent-events.js b/devtools/server/actors/resources/server-sent-events.js
new file mode 100644
index 0000000000..5b16f8bb9f
--- /dev/null
+++ b/devtools/server/actors/resources/server-sent-events.js
@@ -0,0 +1,135 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+      +  * License, v. 2.0. If a copy of the MPL was not distributed with this
+      +  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  LongStringActor,
+} = require("resource://devtools/server/actors/string.js");
+
+const {
+  TYPES: { SERVER_SENT_EVENT },
+} = require("resource://devtools/server/actors/resources/index.js");
+
+const eventSourceEventService = Cc[
+  "@mozilla.org/eventsourceevent/service;1"
+].getService(Ci.nsIEventSourceEventService);
+
+class ServerSentEventWatcher {
+  constructor() {
+    this.windowIds = new Set();
+    // Register for backend events.
+    this.onWindowReady = this.onWindowReady.bind(this);
+    this.onWindowDestroy = this.onWindowDestroy.bind(this);
+  }
+  /**
+   * Start watching for all server sent events related to a given Target Actor.
+   *
+   * @param TargetActor targetActor
+   *        The target actor on which we should observe server sent events.
+   * @param Object options
+   *        Dictionary object with following attributes:
+   *        - onAvailable: mandatory function
+   *          This will be called for each resource.
+   */
+  watch(targetActor, { onAvailable }) {
+    this.onAvailable = onAvailable;
+    this.targetActor = targetActor;
+
+    for (const window of this.targetActor.windows) {
+      const { innerWindowId } = window.windowGlobalChild;
+      this.startListening(innerWindowId);
+    }
+
+    // Listen for subsequent top-level-document reloads/navigations,
+    // new iframe additions or current iframe reloads/navigation.
+    this.targetActor.on("window-ready", this.onWindowReady);
+    this.targetActor.on("window-destroyed", this.onWindowDestroy);
+  }
+
+  static createResource(messageType, eventParams) {
+    return {
+      resourceType: SERVER_SENT_EVENT,
+      messageType,
+      ...eventParams,
+    };
+  }
+
+  static prepareFramePayload(targetActor, frame) {
+    const payload = new LongStringActor(targetActor.conn, frame);
+    targetActor.manage(payload);
+    return payload.form();
+  }
+
+  onWindowReady({ window }) {
+    const { innerWindowId } = window.windowGlobalChild;
+    this.startListening(innerWindowId);
+  }
+
+  onWindowDestroy({ id }) {
+    this.stopListening(id);
+  }
+
+  startListening(innerWindowId) {
+    if (!this.windowIds.has(innerWindowId)) {
+      this.windowIds.add(innerWindowId);
+      eventSourceEventService.addListener(innerWindowId, this);
+    }
+  }
+
+  stopListening(innerWindowId) {
+    if (this.windowIds.has(innerWindowId)) {
+      this.windowIds.delete(innerWindowId);
+      // The listener might have already been cleaned up on `window-destroy`.
+      if (!eventSourceEventService.hasListenerFor(innerWindowId)) {
+        console.warn(
+          "Already stopped listening to server sent events for this window."
+        );
+        return;
+      }
+      eventSourceEventService.removeListener(innerWindowId, this);
+    }
+  }
+
+  destroy() {
+    // cleanup any other listeners not removed on `window-destroy`
+    for (const id of this.windowIds) {
+      this.stopListening(id);
+    }
+    this.targetActor.off("window-ready", this.onWindowReady);
+    this.targetActor.off("window-destroyed", this.onWindowDestroy);
+  }
+
+  // nsIEventSourceEventService specific functions
+  eventSourceConnectionOpened(httpChannelId) {}
+
+  eventSourceConnectionClosed(httpChannelId) {
+    const resource = ServerSentEventWatcher.createResource(
+      "eventSourceConnectionClosed",
+      { httpChannelId }
+    );
+    this.onAvailable([resource]);
+  }
+
+  eventReceived(httpChannelId, eventName, lastEventId, data, retry, timeStamp) {
+    const payload = ServerSentEventWatcher.prepareFramePayload(
+      this.targetActor,
+      data
+    );
+    const resource = ServerSentEventWatcher.createResource("eventReceived", {
+      httpChannelId,
+      data: {
+        payload,
+        eventName,
+        lastEventId,
+        retry,
+        timeStamp,
+      },
+    });
+
+    this.onAvailable([resource]);
+  }
+}
+
+module.exports = ServerSentEventWatcher;