1 files changed, 108 insertions, 0 deletions
diff --git a/toolkit/components/telemetry/other/CombinedStacks.h b/toolkit/components/telemetry/other/CombinedStacks.h
new file mode 100644
index 0000000000..6bd46823db
--- /dev/null
+++ b/toolkit/components/telemetry/other/CombinedStacks.h
@@ -0,0 +1,108 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 CombinedStacks_h__
+#define CombinedStacks_h__
+
+#include <vector>
+
+#include "ipc/IPCMessageUtils.h"
+#include "ProcessedStack.h"
+
+class JSObject;
+struct JSContext;
+
+namespace mozilla {
+namespace Telemetry {
+
+/**
+ * This class is conceptually a list of ProcessedStack objects, but it
+ * represents them more efficiently by keeping a single global list of modules.
+ */
+class CombinedStacks {
+ public:
+  explicit CombinedStacks();
+  explicit CombinedStacks(size_t aMaxStacksCount);
+
+  CombinedStacks(CombinedStacks&&) = default;
+  CombinedStacks& operator=(CombinedStacks&&) = default;
+
+  void Swap(CombinedStacks& aOther);
+
+  typedef std::vector<Telemetry::ProcessedStack::Frame> Stack;
+  const Telemetry::ProcessedStack::Module& GetModule(unsigned aIndex) const;
+  size_t GetModuleCount() const;
+  const Stack& GetStack(unsigned aIndex) const;
+  size_t AddStack(const Telemetry::ProcessedStack& aStack);
+  void AddStacks(const CombinedStacks& aStacks);
+  size_t GetStackCount() const;
+  size_t SizeOfExcludingThis() const;
+  void RemoveStack(unsigned aIndex);
+  size_t GetMaxStacksCount() const;
+
+  /** Clears the contents of vectors and resets the index. */
+  void Clear();
+
+ private:
+  std::vector<Telemetry::ProcessedStack::Module> mModules;
+  // A circular buffer to hold the stacks.
+  std::vector<Stack> mStacks;
+  // The index of the next buffer element to write to in mStacks.
+  size_t mNextIndex;
+  // The maximum number of stacks to keep in the CombinedStacks object.
+  size_t mMaxStacksCount;
+
+  void AddFrame(
+      size_t aStackIndex, const ProcessedStack::Frame& aFrame,
+      const std::function<const ProcessedStack::Module&(int)>& aModuleGetter);
+
+  friend struct ::IPC::ParamTraits<CombinedStacks>;
+};
+
+/**
+ * Creates a JSON representation of given combined stacks object.
+ */
+JSObject* CreateJSStackObject(JSContext* cx, const CombinedStacks& stacks);
+
+}  // namespace Telemetry
+}  // namespace mozilla
+
+namespace IPC {
+
+template <>
+struct ParamTraits<mozilla::Telemetry::CombinedStacks> {
+  typedef mozilla::Telemetry::CombinedStacks paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mModules);
+    WriteParam(aWriter, aParam.mStacks);
+    WriteParam(aWriter, aParam.mNextIndex);
+    WriteParam(aWriter, aParam.mMaxStacksCount);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    if (!ReadParam(aReader, &aResult->mModules)) {
+      return false;
+    }
+
+    if (!ReadParam(aReader, &aResult->mStacks)) {
+      return false;
+    }
+
+    if (!ReadParam(aReader, &aResult->mNextIndex)) {
+      return false;
+    }
+
+    if (!ReadParam(aReader, &aResult->mMaxStacksCount)) {
+      return false;
+    }
+
+    return true;
+  }
+};
+
+}  // namespace IPC
+
+#endif  // CombinedStacks_h__