/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

// Copyright (c) 2006-2008 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: Thread local storage is a bit tricky to get right.  Please make

// sure that this is really the proper solution for what you're trying to

// achieve.  Don't prematurely optimize, most likely you can just use a Lock.

//

// These classes implement a warpper around the platform's TLS storage

// mechanism.  On construction, they will allocate a TLS slot, and free the

// TLS slot on destruction.  No memory management (creation or destruction) is

// handled.  This means for uses of ThreadLocalPointer, you must correctly

// manage the memory yourself, these classes will not destroy the pointer for

// you.  There are no at-thread-exit actions taken by these classes.

//

// ThreadLocalPointer<Type> wraps a Type*.  It performs no creation or

// destruction, so memory management must be handled elsewhere.  The first call

// to Get() on a thread will return NULL.  You can update the pointer with a

// call to Set().

//

// ThreadLocalBoolean wraps a bool.  It will default to false if it has never

// been set otherwise with Set().

//

// Thread Safety:  An instance of ThreadLocalStorage is completely thread safe

// once it has been created.  If you want to dynamically create an instance,

// you must of course properly deal with safety and race conditions.  This

// means a function-level static initializer is generally inappropiate.

//

// Example usage:

//   // My class is logically attached to a single thread.  We cache a pointer

//   // on the thread it was created on, so we can implement current().

//   MyClass::MyClass() {

//     DCHECK(Singleton<ThreadLocalPointer<MyClass> >::get()->Get() == NULL);

//     Singleton<ThreadLocalPointer<MyClass> >::get()->Set(this);

//   }

//

//   MyClass::~MyClass() {

//     DCHECK(Singleton<ThreadLocalPointer<MyClass> >::get()->Get() != NULL);

//     Singleton<ThreadLocalPointer<MyClass> >::get()->Set(NULL);

//   }

//

//   // Return the current MyClass associated with the calling thread, can be

//   // NULL if there isn't a MyClass associated.

//   MyClass* MyClass::current() {

//     return Singleton<ThreadLocalPointer<MyClass> >::get()->Get();

//   }

#ifndef BASE_THREAD_LOCAL_H_

#define BASE_THREAD_LOCAL_H_

#include "base/basictypes.h"

#if defined(OS_POSIX)

#include <pthread.h>

#endif

namespace base {

// Helper functions that abstract the cross-platform APIs.  Do not use directly.

struct ThreadLocalPlatform {

#if defined(OS_WIN)

  typedef int SlotType;

#elif defined(OS_POSIX)

  typedef pthread_key_t SlotType;

#endif

  static void AllocateSlot(SlotType& slot);

  static void FreeSlot(SlotType& slot);

  static void* GetValueFromSlot(SlotType& slot);

  static void SetValueInSlot(SlotType& slot, void* value);

};

template <typename Type>

class ThreadLocalPointer {

 public:

  ThreadLocalPointer() : slot_() {

    ThreadLocalPlatform::AllocateSlot(slot_);

  }

base::ThreadLocalPointer<MessageLoop>::ThreadLocalPointer()

Line

Count

Source

78

3

  ThreadLocalPointer() : slot_() {

79

3

    ThreadLocalPlatform::AllocateSlot(slot_);

80

3

  }

base::ThreadLocalPointer<void>::ThreadLocalPointer()

Line

Count

Source

78

3

  ThreadLocalPointer() : slot_() {

79

3

    ThreadLocalPlatform::AllocateSlot(slot_);

80

3

  }

  ~ThreadLocalPointer() {

    ThreadLocalPlatform::FreeSlot(slot_);

  }

base::ThreadLocalPointer<MessageLoop>::~ThreadLocalPointer()

Line

Count

Source

82

3

  ~ThreadLocalPointer() {

83

3

    ThreadLocalPlatform::FreeSlot(slot_);

84

3

  }

base::ThreadLocalPointer<void>::~ThreadLocalPointer()

Line

Count

Source

82

3

  ~ThreadLocalPointer() {

83

3

    ThreadLocalPlatform::FreeSlot(slot_);

84

3

  }

  Type* Get() {

    return static_cast<Type*>(ThreadLocalPlatform::GetValueFromSlot(slot_));

  }

base::ThreadLocalPointer<MessageLoop>::Get()

Line

Count

Source

86

9

  Type* Get() {

87

9

    return static_cast<Type*>(ThreadLocalPlatform::GetValueFromSlot(slot_));

88

9

  }

Unexecuted instantiation: base::ThreadLocalPointer<void>::Get()

  void Set(Type* ptr) {

    ThreadLocalPlatform::SetValueInSlot(slot_, ptr);

  }

base::ThreadLocalPointer<MessageLoop>::Set(MessageLoop*)

Line

Count

Source

90

19

  void Set(Type* ptr) {

91

19

    ThreadLocalPlatform::SetValueInSlot(slot_, ptr);

92

19

  }

base::ThreadLocalPointer<void>::Set(void*)

Line

Count

Source

90

3

  void Set(Type* ptr) {

91

3

    ThreadLocalPlatform::SetValueInSlot(slot_, ptr);

92

3

  }

 private:

  typedef ThreadLocalPlatform::SlotType SlotType;

  SlotType slot_;

  DISALLOW_COPY_AND_ASSIGN(ThreadLocalPointer<Type>);

};

class ThreadLocalBoolean {

 public:

  ThreadLocalBoolean() { }

  ~ThreadLocalBoolean() { }

  bool Get() {

    return tlp_.Get() != NULL;

  }

  void Set(bool val) {

    uintptr_t intVal = val ? 1 : 0;

    tlp_.Set(reinterpret_cast<void*>(intVal));

  }

 private:

  ThreadLocalPointer<void> tlp_;

  DISALLOW_COPY_AND_ASSIGN(ThreadLocalBoolean);

};

}  // namespace base

#endif  // BASE_THREAD_LOCAL_H_