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 // Copyright (c) 2012 The Chromium Authors. All rights reserved.

 // Use of this source code is governed by a BSD-style license that can be

 // found in the LICENSE file.

 // WARNING: You should *NOT* be using this class directly.  PlatformThread is

 // the low-level platform-specific abstraction to the OS's threading interface.

 // You should instead be using a message-loop driven Thread, see thread.h.

 #ifndef BASE_THREADING_PLATFORM_THREAD_H_

 #define BASE_THREADING_PLATFORM_THREAD_H_

 #include "base/base_export.h"

 #include "base/basictypes.h"

 #include "base/time/time.h"

 #include "build/build_config.h"

 #if defined(OS_WIN)

 #include <windows.h>

 #elif defined(OS_POSIX)

 #include <pthread.h>

 #include <unistd.h>

 #endif

 namespace base {

 #if defined(OS_WIN)

 typedef DWORD PlatformThreadId;

 #elif defined(OS_POSIX)

 typedef pid_t PlatformThreadId;

 #endif

 class PlatformThreadHandle {

  public:

 #if defined(OS_WIN)

   typedef void* Handle;

 #elif defined(OS_POSIX)

   typedef pthread_t Handle;

 #endif

   PlatformThreadHandle()

       : handle_(0),

         id_(0) {

   }

   explicit PlatformThreadHandle(Handle handle)

       : handle_(handle),

         id_(0) {

   }

   PlatformThreadHandle(Handle handle,

                        PlatformThreadId id)

       : handle_(handle),

         id_(id) {

   }

   bool is_equal(const PlatformThreadHandle& other) {

     return handle_ == other.handle_;

   }

   bool is_null() {

     return !handle_;

   }

   Handle platform_handle() {

     return handle_;

   }

  private:

   friend class PlatformThread;

   Handle handle_;

   PlatformThreadId id_;

 };

 const PlatformThreadId kInvalidThreadId(0);

 // Valid values for SetThreadPriority()

 enum ThreadPriority{

   kThreadPriority_Normal,

   // Suitable for low-latency, glitch-resistant audio.

   kThreadPriority_RealtimeAudio,

   // Suitable for threads which generate data for the display (at ~60Hz).

   kThreadPriority_Display,

   // Suitable for threads that shouldn't disrupt high priority work.

   kThreadPriority_Background

 };

 // A namespace for low-level thread functions.

 class BASE_EXPORT PlatformThread {

  public:

   // Implement this interface to run code on a background thread.  Your

   // ThreadMain method will be called on the newly created thread.

   class BASE_EXPORT Delegate {

    public:

     virtual void ThreadMain() = 0;

    protected:

     virtual ~Delegate() {}

   };

   // Gets the current thread id, which may be useful for logging purposes.

   static PlatformThreadId CurrentId();

   // Get the current handle.

   static PlatformThreadHandle CurrentHandle();

   // Yield the current thread so another thread can be scheduled.

   static void YieldCurrentThread();

   // Sleeps for the specified duration.

   static void Sleep(base::TimeDelta duration);

   // Sets the thread name visible to debuggers/tools. This has no effect

   // otherwise. This name pointer is not copied internally. Thus, it must stay

   // valid until the thread ends.

   static void SetName(const char* name);

   // Gets the thread name, if previously set by SetName.

   static const char* GetName();

   // Creates a new thread.  The |stack_size| parameter can be 0 to indicate

   // that the default stack size should be used.  Upon success,

   // |*thread_handle| will be assigned a handle to the newly created thread,

   // and |delegate|'s ThreadMain method will be executed on the newly created

   // thread.

   // NOTE: When you are done with the thread handle, you must call Join to

   // release system resources associated with the thread.  You must ensure that

   // the Delegate object outlives the thread.

   static bool Create(size_t stack_size, Delegate* delegate,

                      PlatformThreadHandle* thread_handle);

   // CreateWithPriority() does the same thing as Create() except the priority of

   // the thread is set based on |priority|.  Can be used in place of Create()

   // followed by SetThreadPriority().  SetThreadPriority() has not been

   // implemented on the Linux platform yet, this is the only way to get a high

   // priority thread on Linux.

   static bool CreateWithPriority(size_t stack_size, Delegate* delegate,

                                  PlatformThreadHandle* thread_handle,

                                  ThreadPriority priority);

   // CreateNonJoinable() does the same thing as Create() except the thread

   // cannot be Join()'d.  Therefore, it also does not output a

   // PlatformThreadHandle.

   static bool CreateNonJoinable(size_t stack_size, Delegate* delegate);

   // Joins with a thread created via the Create function.  This function blocks

   // the caller until the designated thread exits.  This will invalidate

   // |thread_handle|.

   static void Join(PlatformThreadHandle thread_handle);

   static void SetThreadPriority(PlatformThreadHandle handle,

                                 ThreadPriority priority);

  private:

   DISALLOW_IMPLICIT_CONSTRUCTORS(PlatformThread);

 };

 }  // namespace base

 #endif  // BASE_THREADING_PLATFORM_THREAD_H_