1 files changed, 147 insertions, 0 deletions
diff --git a/xpcom/threads/ThreadStackHelper.h b/xpcom/threads/ThreadStackHelper.h
new file mode 100644
index 000000000..9c40ad5e2
--- /dev/null
+++ b/xpcom/threads/ThreadStackHelper.h
@@ -0,0 +1,147 @@
+/* -*- 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
+
+#include "mozilla/ThreadHangStats.h"
+
+#include "GeckoProfiler.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 pseudostack on these platforms.
+#if defined(XP_LINUX) || defined(XP_WIN) || defined(XP_MACOSX)
+#  ifdef MOZ_ENABLE_PROFILER_SPS
+#    define MOZ_THREADSTACKHELPER_PSEUDO
+#  endif
+#endif
+
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+#  define MOZ_THREADSTACKHELPER_NATIVE
+#  if defined(__i386__) || defined(_M_IX86)
+#    define MOZ_THREADSTACKHELPER_X86
+#  elif defined(__x86_64__) || defined(_M_X64)
+#    define MOZ_THREADSTACKHELPER_X64
+#  elif defined(__arm__) || defined(_M_ARM)
+#    define MOZ_THREADSTACKHELPER_ARM
+#  else
+     // Unsupported architecture
+#    undef MOZ_THREADSTACKHELPER_NATIVE
+#  endif
+#endif
+
+namespace mozilla {
+
+/**
+ * ThreadStackHelper is used to retrieve the profiler pseudo-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 pseudo-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:
+  typedef Telemetry::HangStack Stack;
+
+private:
+  Stack* mStackToFill;
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+  const PseudoStack* const mPseudoStack;
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+  class ThreadContext;
+  // Set to non-null if GetStack should get the thread context.
+  ThreadContext* mContextToFill;
+  intptr_t mThreadStackBase;
+#endif
+  size_t mMaxStackSize;
+  size_t mMaxBufferSize;
+#endif
+
+  bool PrepareStackBuffer(Stack& aStack);
+  void FillStackBuffer();
+  void FillThreadContext(void* aContext = nullptr);
+#ifdef MOZ_THREADSTACKHELPER_PSEUDO
+  const char* AppendJSEntry(const volatile StackEntry* aEntry,
+                            intptr_t& aAvailableBufferSize,
+                            const char* aPrevLabel);
+#endif
+#ifdef MOZ_THREADSTACKHELPER_NATIVE
+  void GetThreadStackBase();
+#endif
+
+public:
+  /**
+   * Initialize ThreadStackHelper. Must be called from main thread.
+   */
+  static void Startup();
+  /**
+   * Uninitialize ThreadStackHelper. Must be called from main thread.
+   */
+  static void Shutdown();
+
+  /**
+   * Create a ThreadStackHelper instance targeting the current thread.
+   */
+  ThreadStackHelper();
+
+  ~ThreadStackHelper();
+
+  /**
+   * Retrieve the current pseudostack of the thread associated
+   * with this ThreadStackHelper.
+   *
+   * @param aStack Stack instance to be filled.
+   */
+  void GetStack(Stack& aStack);
+
+  /**
+   * Retrieve the current native stack of the thread associated
+   * with this ThreadStackHelper.
+   *
+   * @param aNativeStack Stack instance to be filled.
+   */
+  void GetNativeStack(Stack& aStack);
+
+#if defined(XP_LINUX)
+private:
+  static int sInitialized;
+  static int sFillStackSignum;
+
+  static void FillStackHandler(int aSignal, siginfo_t* aInfo, void* aContext);
+
+  sem_t mSem;
+  pid_t mThreadID;
+
+#elif defined(XP_WIN)
+private:
+  bool mInitialized;
+  HANDLE mThreadID;
+
+#elif defined(XP_MACOSX)
+private:
+  thread_act_t mThreadID;
+
+#endif
+};
+
+} // namespace mozilla
+
+#endif // mozilla_ThreadStackHelper_h