1 files changed, 72 insertions, 0 deletions
diff --git a/xpcom/base/MemoryTelemetry.h b/xpcom/base/MemoryTelemetry.h
new file mode 100644
index 0000000000..b7c7fe8ad6
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+++ b/xpcom/base/MemoryTelemetry.h
@@ -0,0 +1,72 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_MemoryTelemetry_h
+#define mozilla_MemoryTelemetry_h
+
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Result.h"
+#include "nsIObserver.h"
+#include "nsITimer.h"
+#include "nsTArray.h"
+#include "nsWeakReference.h"
+
+#include <functional>
+
+class nsIEventTarget;
+
+namespace mozilla {
+
+namespace ipc {
+enum class ResponseRejectReason;
+}
+
+/**
+ * Periodically gathers memory usage metrics after cycle collection, and
+ * populates telemetry histograms with their values.
+ */
+class MemoryTelemetry final : public nsIObserver,
+                              public nsSupportsWeakReference {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  static MemoryTelemetry& Get();
+
+  nsresult GatherReports(
+      const std::function<void()>& aCompletionCallback = nullptr);
+
+  /**
+   * Does expensive initialization, which should happen only after startup has
+   * completed, and the event loop is idle.
+   */
+  nsresult DelayedInit();
+
+  nsresult Shutdown();
+
+ private:
+  MemoryTelemetry();
+
+  ~MemoryTelemetry() = default;
+
+  void Init();
+
+  static Result<uint32_t, nsresult> GetOpenTabsCount();
+
+  void GatherTotalMemory();
+  nsresult FinishGatheringTotalMemory(int64_t aTotalMemory,
+                                      const nsTArray<int64_t>& aChildSizes);
+
+  nsCOMPtr<nsIEventTarget> mThreadPool;
+
+  bool mGatheringTotalMemory = false;
+
+  TimeStamp mLastPoll{};
+};
+
+}  // namespace mozilla
+
+#endif  // defined mozilla_MemoryTelemetry_h