1 files changed, 41 insertions, 0 deletions
diff --git a/toolkit/components/telemetry/app/TelemetryController.sys.mjs b/toolkit/components/telemetry/app/TelemetryController.sys.mjs
new file mode 100644
index 0000000000..e994181f39
--- /dev/null
+++ b/toolkit/components/telemetry/app/TelemetryController.sys.mjs
@@ -0,0 +1,41 @@
+/* -*- js-indent-level: 2; indent-tabs-mode: nil -*- */
+/* 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 module chooses the correct telemetry controller module to load
+ * based on the process:
+ *
+ * - TelemetryControllerParent is loaded only in the parent process, and
+ *   contains code specific to the parent.
+ * - TelemetryControllerContent is loaded only in content processes, and
+ *   contains code specific to them.
+ *
+ * Both the parent and the content modules load TelemetryControllerBase,
+ * which contains code which is common to all processes.
+ *
+ * This division is important for content process memory usage and
+ * startup time. The parent-specific code occupies tens of KB of memory
+ * which, multiplied by the number of content processes we have, adds up
+ * fast.
+ */
+
+// We can't use Services.appinfo here because tests stub out the appinfo
+// service, and if we touch Services.appinfo now, the built-in version
+// will be cached in place of the stub.
+const isParentProcess =
+  // eslint-disable-next-line mozilla/use-services
+  Cc["@mozilla.org/xre/app-info;1"].getService(Ci.nsIXULRuntime).processType ===
+  Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
+
+export var TelemetryController;
+if (isParentProcess) {
+  ({ TelemetryController } = ChromeUtils.importESModule(
+    "resource://gre/modules/TelemetryControllerParent.sys.mjs"
+  ));
+} else {
+  ({ TelemetryController } = ChromeUtils.importESModule(
+    "resource://gre/modules/TelemetryControllerContent.sys.mjs"
+  ));
+}