1 files changed, 77 insertions, 0 deletions
diff --git a/toolkit/modules/Memory.jsm b/toolkit/modules/Memory.jsm
new file mode 100644
index 000000000..bb8e331c6
--- /dev/null
+++ b/toolkit/modules/Memory.jsm
@@ -0,0 +1,77 @@
+/* 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/. */
+
+this.EXPORTED_SYMBOLS = ["Memory"];
+
+const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
+// How long we should wait for the Promise to resolve.
+const TIMEOUT_INTERVAL = 2000;
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/Timer.jsm");
+
+this.Memory = {
+  /**
+   * This function returns a Promise that resolves with an Object that
+   * describes basic memory usage for each content process and the parent
+   * process.
+   * @returns Promise
+   * @resolves JS Object
+   * An Object in the following format:
+   * {
+   *   "parent": {
+   *     uss: <int>,
+   *     rss: <int>,
+   *   },
+   *   <pid>: {
+   *     uss: <int>,
+   *     rss: <int>,
+   *   },
+   *   ...
+   * }
+   */
+  summary() {
+    if (!this._pendingPromise) {
+      this._pendingPromise = new Promise((resolve) => {
+        this._pendingResolve = resolve;
+        this._summaries = {};
+        Services.ppmm.broadcastAsyncMessage("Memory:GetSummary");
+        Services.ppmm.addMessageListener("Memory:Summary", this);
+        this._pendingTimeout = setTimeout(() => { this.finish(); }, TIMEOUT_INTERVAL);
+      });
+    }
+    return this._pendingPromise;
+  },
+
+  receiveMessage(msg) {
+    if (msg.name != "Memory:Summary" || !this._pendingResolve) {
+      return;
+    }
+    this._summaries[msg.data.pid] = msg.data.summary;
+    // Now we check if we are done for all content processes.
+    // Services.ppmm.childCount is a count of how many processes currently
+    // exist that might respond to messages sent through the ppmm, including
+    // the parent process. So we subtract the parent process with the "- 1",
+    // and that’s how many content processes we’re waiting for.
+    if (Object.keys(this._summaries).length >= Services.ppmm.childCount - 1) {
+      this.finish();
+    }
+  },
+
+  finish() {
+    // Code to gather the USS and RSS values for the parent process. This
+    // functions the same way as in process-content.js.
+    let memMgr = Cc["@mozilla.org/memory-reporter-manager;1"]
+                   .getService(Ci.nsIMemoryReporterManager);
+    let rss = memMgr.resident;
+    let uss = memMgr.residentUnique;
+    this._summaries["Parent"] = { uss, rss };
+    this._pendingResolve(this._summaries);
+    this._pendingResolve = null;
+    this._summaries = null;
+    this._pendingPromise = null;
+    clearTimeout(this._pendingTimeout);
+    Services.ppmm.removeMessageListener("Memory:Summary", this);
+  }
+};