1 files changed, 111 insertions, 0 deletions
diff --git a/toolkit/components/backgroundhangmonitor/ThreadStackHelper.h b/toolkit/components/backgroundhangmonitor/ThreadStackHelper.h
new file mode 100644
index 0000000000..e54078d2dd
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+++ b/toolkit/components/backgroundhangmonitor/ThreadStackHelper.h
@@ -0,0 +1,111 @@
+/* -*- 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_ThreadStackHelper_h
+#define mozilla_ThreadStackHelper_h
+
+#ifdef MOZ_GECKO_PROFILER
+
+#  include "js/ProfilingStack.h"
+#  include "GeckoProfiler.h"
+#  include "HangDetails.h"
+#  include "mozilla/Span.h"
+#  include "nsThread.h"
+
+#  include <stddef.h>
+
+#  if defined(XP_LINUX)
+#    include <signal.h>
+#    include <semaphore.h>
+#    include <sys/types.h>
+#  elif defined(XP_WIN)
+#    include <windows.h>
+#  elif defined(XP_MACOSX)
+#    include <mach/mach.h>
+#  endif
+
+// Support profiling stack and native stack on these platforms.
+#  if defined(XP_LINUX) || defined(XP_WIN) || defined(XP_MACOSX)
+#    define MOZ_THREADSTACKHELPER_PROFILING_STACK
+#    define MOZ_THREADSTACKHELPER_NATIVE_STACK
+#  endif
+
+// Android x86 builds consistently crash in the Background Hang Reporter. bug
+// 1368520.
+#  if defined(__ANDROID__)
+#    undef MOZ_THREADSTACKHELPER_PROFILING_STACK
+#    undef MOZ_THREADSTACKHELPER_NATIVE_STACK
+#  endif
+
+namespace mozilla {
+
+/**
+ * ThreadStackHelper is used to retrieve the profiler's "profiling stack" of a
+ * thread, as an alternative of using the profiler to take a profile.
+ * The target thread first declares an ThreadStackHelper instance;
+ * then another thread can call ThreadStackHelper::GetStack to retrieve
+ * the profiling stack of the target thread at that instant.
+ *
+ * Only non-copying labels are included in the stack, which means labels
+ * with custom text and markers are not included.
+ */
+class ThreadStackHelper : public ProfilerStackCollector {
+ private:
+  HangStack* mStackToFill;
+  Array<char, nsThread::kRunnableNameBufSize>* mRunnableNameBuffer;
+  size_t mMaxStackSize;
+  size_t mMaxBufferSize;
+  size_t mDesiredStackSize;
+  size_t mDesiredBufferSize;
+
+  bool PrepareStackBuffer(HangStack& aStack);
+
+ public:
+  /**
+   * Create a ThreadStackHelper instance targeting the current thread.
+   */
+  ThreadStackHelper();
+
+  /**
+   * Retrieve the current interleaved stack of the thread associated with this
+   * ThreadStackHelper.
+   *
+   * @param aStack        HangStack instance to be filled.
+   * @param aRunnableName The name of the current runnable on the target thread.
+   * @param aStackWalk    If true, native stack frames will be collected
+   *                      along with profiling stack frames.
+   */
+  void GetStack(HangStack& aStack, nsACString& aRunnableName, bool aStackWalk);
+
+  /**
+   * Retrieve the thread's profiler thread ID.
+   */
+  ProfilerThreadId GetThreadId() const { return mThreadId; }
+
+ protected:
+  /**
+   * ProfilerStackCollector
+   */
+  virtual void SetIsMainThread() override;
+  virtual void CollectNativeLeafAddr(void* aAddr) override;
+  virtual void CollectJitReturnAddr(void* aAddr) override;
+  virtual void CollectWasmFrame(const char* aLabel) override;
+  virtual void CollectProfilingStackFrame(
+      const js::ProfilingStackFrame& aEntry) override;
+
+ private:
+  bool MaybeAppendDynamicStackFrame(mozilla::Span<const char> aBuf);
+  void TryAppendFrame(mozilla::HangEntry aFrame);
+
+  // The profiler's unique thread identifier for the target thread.
+  ProfilerThreadId mThreadId;
+};
+
+}  // namespace mozilla
+
+#endif  // MOZ_GECKO_PROFILER
+
+#endif  // mozilla_ThreadStackHelper_h