Move thread local stuff from base to base/threading and consistently use the

base namespace. This also fixes references to TLSSlot to
base::ThreadLocalStorage::Slot.

TEST=it compiles
BUG=none
Review URL: http://codereview.chromium.org/5986012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@70322 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 813 insertions, 0 deletions

diff --git a/base/threading/thread_local.h b/base/threading/thread_local.h
new file mode 100644
index 0000000..069543f
--- /dev/null
+++ b/base/threading/thread_local.h
@@ -0,0 +1,127 @@
+// Copyright (c) 2010 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 wrapper 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_THREADING_THREAD_LOCAL_H_
+#define BASE_THREADING_THREAD_LOCAL_H_
+#pragma once
+
+#include "base/basictypes.h"
+
+#if defined(OS_POSIX)
+#include <pthread.h>
+#endif
+
+namespace base {
+
+namespace internal {
+
+// Helper functions that abstract the cross-platform APIs.  Do not use directly.
+struct ThreadLocalPlatform {
+#if defined(OS_WIN)
+  typedef unsigned long 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);
+};
+
+}  // namespace internal
+
+template <typename Type>
+class ThreadLocalPointer {
+ public:
+  ThreadLocalPointer() : slot_() {
+    internal::ThreadLocalPlatform::AllocateSlot(slot_);
+  }
+
+  ~ThreadLocalPointer() {
+    internal::ThreadLocalPlatform::FreeSlot(slot_);
+  }
+
+  Type* Get() {
+    return static_cast<Type*>(
+        internal::ThreadLocalPlatform::GetValueFromSlot(slot_));
+  }
+
+  void Set(Type* ptr) {
+    internal::ThreadLocalPlatform::SetValueInSlot(slot_, ptr);
+  }
+
+ private:
+  typedef internal::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) {
+    tlp_.Set(reinterpret_cast<void*>(val ? 1 : 0));
+  }
+
+ private:
+  ThreadLocalPointer<void> tlp_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadLocalBoolean);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_LOCAL_H_
diff --git a/base/threading/thread_local_posix.cc b/base/threading/thread_local_posix.cc
new file mode 100644
index 0000000..568fa4b
--- /dev/null
+++ b/base/threading/thread_local_posix.cc
@@ -0,0 +1,40 @@
+// Copyright (c) 2010 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.
+
+#include "base/threading/thread_local.h"
+
+#include <pthread.h>
+
+#include "base/logging.h"
+
+namespace base {
+
+namespace internal {
+
+// static
+void ThreadLocalPlatform::AllocateSlot(SlotType& slot) {
+  int error = pthread_key_create(&slot, NULL);
+  CHECK_EQ(error, 0);
+}
+
+// static
+void ThreadLocalPlatform::FreeSlot(SlotType& slot) {
+  int error = pthread_key_delete(slot);
+  DCHECK(error == 0);
+}
+
+// static
+void* ThreadLocalPlatform::GetValueFromSlot(SlotType& slot) {
+  return pthread_getspecific(slot);
+}
+
+// static
+void ThreadLocalPlatform::SetValueInSlot(SlotType& slot, void* value) {
+  int error = pthread_setspecific(slot, value);
+  CHECK_EQ(error, 0);
+}
+
+}  // namespace internal
+
+}  // namespace base
diff --git a/base/threading/thread_local_storage.h b/base/threading/thread_local_storage.h
new file mode 100644
index 0000000..204b6530
--- /dev/null
+++ b/base/threading/thread_local_storage.h
@@ -0,0 +1,95 @@
+// 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.
+
+#ifndef BASE_THREADING_THREAD_LOCAL_STORAGE_H_
+#define BASE_THREADING_THREAD_LOCAL_STORAGE_H_
+#pragma once
+
+#include "base/basictypes.h"
+
+#if defined(OS_POSIX)
+#include <pthread.h>
+#endif
+
+namespace base {
+
+// Wrapper for thread local storage.  This class doesn't do much except provide
+// an API for portability.
+class ThreadLocalStorage {
+ public:
+
+  // Prototype for the TLS destructor function, which can be optionally used to
+  // cleanup thread local storage on thread exit.  'value' is the data that is
+  // stored in thread local storage.
+  typedef void (*TLSDestructorFunc)(void* value);
+
+  // A key representing one value stored in TLS.
+  class Slot {
+   public:
+    explicit Slot(TLSDestructorFunc destructor = NULL);
+
+    // This constructor should be used for statics.
+    // It returns an uninitialized Slot.
+    explicit Slot(base::LinkerInitialized x) {}
+
+    // Set up the TLS slot.  Called by the constructor.
+    // 'destructor' is a pointer to a function to perform per-thread cleanup of
+    // this object.  If set to NULL, no cleanup is done for this TLS slot.
+    // Returns false on error.
+    bool Initialize(TLSDestructorFunc destructor);
+
+    // Free a previously allocated TLS 'slot'.
+    // If a destructor was set for this slot, removes
+    // the destructor so that remaining threads exiting
+    // will not free data.
+    void Free();
+
+    // Get the thread-local value stored in slot 'slot'.
+    // Values are guaranteed to initially be zero.
+    void* Get() const;
+
+    // Set the thread-local value stored in slot 'slot' to
+    // value 'value'.
+    void Set(void* value);
+
+    bool initialized() const { return initialized_; }
+
+   private:
+    // The internals of this struct should be considered private.
+    bool initialized_;
+#if defined(OS_WIN)
+    int slot_;
+#elif defined(OS_POSIX)
+    pthread_key_t key_;
+#endif
+
+    DISALLOW_COPY_AND_ASSIGN(Slot);
+  };
+
+#if defined(OS_WIN)
+  // Function called when on thread exit to call TLS
+  // destructor functions.  This function is used internally.
+  static void ThreadExit();
+
+ private:
+  // Function to lazily initialize our thread local storage.
+  static void **Initialize();
+
+ private:
+  // The maximum number of 'slots' in our thread local storage stack.
+  // For now, this is fixed.  We could either increase statically, or
+  // we could make it dynamic in the future.
+  static const int kThreadLocalStorageSize = 64;
+
+  static long tls_key_;
+  static long tls_max_;
+  static TLSDestructorFunc tls_destructors_[kThreadLocalStorageSize];
+#endif  // OS_WIN
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorage);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_LOCAL_STORAGE_H_
diff --git a/base/threading/thread_local_storage_posix.cc b/base/threading/thread_local_storage_posix.cc
new file mode 100644
index 0000000..81b7332
--- /dev/null
+++ b/base/threading/thread_local_storage_posix.cc
@@ -0,0 +1,48 @@
+// Copyright (c) 2010 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.
+
+#include "base/threading/thread_local_storage.h"
+
+#include "base/logging.h"
+
+namespace base {
+
+ThreadLocalStorage::Slot::Slot(TLSDestructorFunc destructor)
+    : initialized_(false) {
+  Initialize(destructor);
+}
+
+bool ThreadLocalStorage::Slot::Initialize(TLSDestructorFunc destructor) {
+  DCHECK(!initialized_);
+  int error = pthread_key_create(&key_, destructor);
+  if (error) {
+    NOTREACHED();
+    return false;
+  }
+
+  initialized_ = true;
+  return true;
+}
+
+void ThreadLocalStorage::Slot::Free() {
+  DCHECK(initialized_);
+  int error = pthread_key_delete(key_);
+  if (error)
+    NOTREACHED();
+  initialized_ = false;
+}
+
+void* ThreadLocalStorage::Slot::Get() const {
+  DCHECK(initialized_);
+  return pthread_getspecific(key_);
+}
+
+void ThreadLocalStorage::Slot::Set(void* value) {
+  DCHECK(initialized_);
+  int error = pthread_setspecific(key_, value);
+  if (error)
+    NOTREACHED();
+}
+
+}  // namespace base
diff --git a/base/threading/thread_local_storage_unittest.cc b/base/threading/thread_local_storage_unittest.cc
new file mode 100644
index 0000000..216e650
--- /dev/null
+++ b/base/threading/thread_local_storage_unittest.cc
@@ -0,0 +1,100 @@
+// Copyright (c) 2010 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.
+
+#if defined(OS_WIN)
+#include <windows.h>
+#include <process.h>
+#endif
+
+#include "base/threading/simple_thread.h"
+#include "base/threading/thread_local_storage.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+#if defined(OS_WIN)
+// Ignore warnings about ptr->int conversions that we use when
+// storing ints into ThreadLocalStorage.
+#pragma warning(disable : 4311 4312)
+#endif
+
+namespace base {
+
+namespace {
+
+const int kInitialTlsValue = 0x5555;
+static ThreadLocalStorage::Slot tls_slot(LINKER_INITIALIZED);
+
+class ThreadLocalStorageRunner : public DelegateSimpleThread::Delegate {
+ public:
+  explicit ThreadLocalStorageRunner(int* tls_value_ptr)
+      : tls_value_ptr_(tls_value_ptr) {}
+
+  virtual ~ThreadLocalStorageRunner() {}
+
+  virtual void Run() {
+    *tls_value_ptr_ = kInitialTlsValue;
+    tls_slot.Set(tls_value_ptr_);
+
+    int *ptr = static_cast<int*>(tls_slot.Get());
+    EXPECT_EQ(ptr, tls_value_ptr_);
+    EXPECT_EQ(*ptr, kInitialTlsValue);
+    *tls_value_ptr_ = 0;
+
+    ptr = static_cast<int*>(tls_slot.Get());
+    EXPECT_EQ(ptr, tls_value_ptr_);
+    EXPECT_EQ(*ptr, 0);
+  }
+
+ private:
+  int* tls_value_ptr_;
+  DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorageRunner);
+};
+
+
+void ThreadLocalStorageCleanup(void *value) {
+  int *ptr = reinterpret_cast<int*>(value);
+  if (ptr)
+    *ptr = kInitialTlsValue;
+}
+
+}  // namespace
+
+TEST(ThreadLocalStorageTest, Basics) {
+  ThreadLocalStorage::Slot slot;
+  slot.Set(reinterpret_cast<void*>(123));
+  int value = reinterpret_cast<intptr_t>(slot.Get());
+  EXPECT_EQ(value, 123);
+}
+
+TEST(ThreadLocalStorageTest, TLSDestructors) {
+  // Create a TLS index with a destructor.  Create a set of
+  // threads that set the TLS, while the destructor cleans it up.
+  // After the threads finish, verify that the value is cleaned up.
+  const int kNumThreads = 5;
+  int values[kNumThreads];
+  ThreadLocalStorageRunner* thread_delegates[kNumThreads];
+  DelegateSimpleThread* threads[kNumThreads];
+
+  tls_slot.Initialize(ThreadLocalStorageCleanup);
+
+  // Spawn the threads.
+  for (int index = 0; index < kNumThreads; index++) {
+    values[index] = kInitialTlsValue;
+    thread_delegates[index] = new ThreadLocalStorageRunner(&values[index]);
+    threads[index] = new DelegateSimpleThread(thread_delegates[index],
+                                              "tls thread");
+    threads[index]->Start();
+  }
+
+  // Wait for the threads to finish.
+  for (int index = 0; index < kNumThreads; index++) {
+    threads[index]->Join();
+    delete threads[index];
+    delete thread_delegates[index];
+
+    // Verify that the destructor was called and that we reset.
+    EXPECT_EQ(values[index], kInitialTlsValue);
+  }
+}
+
+}  // namespace base
diff --git a/base/threading/thread_local_storage_win.cc b/base/threading/thread_local_storage_win.cc
new file mode 100644
index 0000000..2967a27
--- /dev/null
+++ b/base/threading/thread_local_storage_win.cc
@@ -0,0 +1,198 @@
+// Copyright (c) 2010 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.
+
+#include "base/threading/thread_local_storage.h"
+
+#include <windows.h>
+
+#include "base/logging.h"
+
+namespace base {
+
+// In order to make TLS destructors work, we need to keep function
+// pointers to the destructor for each TLS that we allocate.
+// We make this work by allocating a single OS-level TLS, which
+// contains an array of slots for the application to use.  In
+// parallel, we also allocate an array of destructors, which we
+// keep track of and call when threads terminate.
+
+// tls_key_ is the one native TLS that we use.  It stores our
+// table.
+long ThreadLocalStorage::tls_key_ = TLS_OUT_OF_INDEXES;
+
+// tls_max_ is the high-water-mark of allocated thread local storage.
+// We intentionally skip 0 so that it is not confused with an
+// unallocated TLS slot.
+long ThreadLocalStorage::tls_max_ = 1;
+
+// An array of destructor function pointers for the slots.  If
+// a slot has a destructor, it will be stored in its corresponding
+// entry in this array.
+ThreadLocalStorage::TLSDestructorFunc
+  ThreadLocalStorage::tls_destructors_[kThreadLocalStorageSize];
+
+void** ThreadLocalStorage::Initialize() {
+  if (tls_key_ == TLS_OUT_OF_INDEXES) {
+    long value = TlsAlloc();
+    DCHECK(value != TLS_OUT_OF_INDEXES);
+
+    // Atomically test-and-set the tls_key.  If the key is TLS_OUT_OF_INDEXES,
+    // go ahead and set it.  Otherwise, do nothing, as another
+    // thread already did our dirty work.
+    if (InterlockedCompareExchange(&tls_key_, value, TLS_OUT_OF_INDEXES) !=
+            TLS_OUT_OF_INDEXES) {
+      // We've been shortcut. Another thread replaced tls_key_ first so we need
+      // to destroy our index and use the one the other thread got first.
+      TlsFree(value);
+    }
+  }
+  DCHECK(TlsGetValue(tls_key_) == NULL);
+
+  // Create an array to store our data.
+  void** tls_data = new void*[kThreadLocalStorageSize];
+  memset(tls_data, 0, sizeof(void*[kThreadLocalStorageSize]));
+  TlsSetValue(tls_key_, tls_data);
+  return tls_data;
+}
+
+ThreadLocalStorage::Slot::Slot(TLSDestructorFunc destructor)
+    : initialized_(false) {
+  Initialize(destructor);
+}
+
+bool ThreadLocalStorage::Slot::Initialize(TLSDestructorFunc destructor) {
+  if (tls_key_ == TLS_OUT_OF_INDEXES || !TlsGetValue(tls_key_))
+    ThreadLocalStorage::Initialize();
+
+  // Grab a new slot.
+  slot_ = InterlockedIncrement(&tls_max_) - 1;
+  if (slot_ >= kThreadLocalStorageSize) {
+    NOTREACHED();
+    return false;
+  }
+
+  // Setup our destructor.
+  tls_destructors_[slot_] = destructor;
+  initialized_ = true;
+  return true;
+}
+
+void ThreadLocalStorage::Slot::Free() {
+  // At this time, we don't reclaim old indices for TLS slots.
+  // So all we need to do is wipe the destructor.
+  tls_destructors_[slot_] = NULL;
+  initialized_ = false;
+}
+
+void* ThreadLocalStorage::Slot::Get() const {
+  void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
+  if (!tls_data)
+    tls_data = ThreadLocalStorage::Initialize();
+  DCHECK(slot_ >= 0 && slot_ < kThreadLocalStorageSize);
+  return tls_data[slot_];
+}
+
+void ThreadLocalStorage::Slot::Set(void* value) {
+  void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
+  if (!tls_data)
+    tls_data = ThreadLocalStorage::Initialize();
+  DCHECK(slot_ >= 0 && slot_ < kThreadLocalStorageSize);
+  tls_data[slot_] = value;
+}
+
+void ThreadLocalStorage::ThreadExit() {
+  if (tls_key_ == TLS_OUT_OF_INDEXES)
+    return;
+
+  void** tls_data = static_cast<void**>(TlsGetValue(tls_key_));
+
+  // Maybe we have never initialized TLS for this thread.
+  if (!tls_data)
+    return;
+
+  for (int slot = 0; slot < tls_max_; slot++) {
+    if (tls_destructors_[slot] != NULL) {
+      void* value = tls_data[slot];
+      tls_destructors_[slot](value);
+    }
+  }
+
+  delete[] tls_data;
+
+  // In case there are other "onexit" handlers...
+  TlsSetValue(tls_key_, NULL);
+}
+
+}  // namespace base
+
+// Thread Termination Callbacks.
+// Windows doesn't support a per-thread destructor with its
+// TLS primitives.  So, we build it manually by inserting a
+// function to be called on each thread's exit.
+// This magic is from http://www.codeproject.com/threads/tls.asp
+// and it works for VC++ 7.0 and later.
+
+// Force a reference to _tls_used to make the linker create the TLS directory
+// if it's not already there.  (e.g. if __declspec(thread) is not used).
+// Force a reference to p_thread_callback_base to prevent whole program
+// optimization from discarding the variable.
+#ifdef _WIN64
+
+#pragma comment(linker, "/INCLUDE:_tls_used")
+#pragma comment(linker, "/INCLUDE:p_thread_callback_base")
+
+#else  // _WIN64
+
+#pragma comment(linker, "/INCLUDE:__tls_used")
+#pragma comment(linker, "/INCLUDE:_p_thread_callback_base")
+
+#endif  // _WIN64
+
+// Static callback function to call with each thread termination.
+void NTAPI OnThreadExit(PVOID module, DWORD reason, PVOID reserved) {
+  // On XP SP0 & SP1, the DLL_PROCESS_ATTACH is never seen. It is sent on SP2+
+  // and on W2K and W2K3. So don't assume it is sent.
+  if (DLL_THREAD_DETACH == reason || DLL_PROCESS_DETACH == reason)
+    base::ThreadLocalStorage::ThreadExit();
+}
+
+// .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are
+// called automatically by the OS loader code (not the CRT) when the module is
+// loaded and on thread creation. They are NOT called if the module has been
+// loaded by a LoadLibrary() call. It must have implicitly been loaded at
+// process startup.
+// By implicitly loaded, I mean that it is directly referenced by the main EXE
+// or by one of its dependent DLLs. Delay-loaded DLL doesn't count as being
+// implicitly loaded.
+//
+// See VC\crt\src\tlssup.c for reference.
+
+// extern "C" suppresses C++ name mangling so we know the symbol name for the
+// linker /INCLUDE:symbol pragma above.
+extern "C" {
+// The linker must not discard p_thread_callback_base.  (We force a reference
+// to this variable with a linker /INCLUDE:symbol pragma to ensure that.) If
+// this variable is discarded, the OnThreadExit function will never be called.
+#ifdef _WIN64
+
+// .CRT section is merged with .rdata on x64 so it must be constant data.
+#pragma const_seg(".CRT$XLB")
+// When defining a const variable, it must have external linkage to be sure the
+// linker doesn't discard it.
+extern const PIMAGE_TLS_CALLBACK p_thread_callback_base;
+const PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit;
+
+// Reset the default section.
+#pragma const_seg()
+
+#else  // _WIN64
+
+#pragma data_seg(".CRT$XLB")
+PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit;
+
+// Reset the default section.
+#pragma data_seg()
+
+#endif  // _WIN64
+}  // extern "C"
diff --git a/base/threading/thread_local_unittest.cc b/base/threading/thread_local_unittest.cc
new file mode 100644
index 0000000..f6bdd78
--- /dev/null
+++ b/base/threading/thread_local_unittest.cc
@@ -0,0 +1,163 @@
+// Copyright (c) 2010 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.
+
+#include "base/logging.h"
+#include "base/threading/simple_thread.h"
+#include "base/threading/thread_local.h"
+#include "base/waitable_event.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+class ThreadLocalTesterBase : public base::DelegateSimpleThreadPool::Delegate {
+ public:
+  typedef base::ThreadLocalPointer<ThreadLocalTesterBase> TLPType;
+
+  ThreadLocalTesterBase(TLPType* tlp, base::WaitableEvent* done)
+      : tlp_(tlp), done_(done) { }
+  ~ThreadLocalTesterBase() { }
+
+ protected:
+  TLPType* tlp_;
+  base::WaitableEvent* done_;
+};
+
+class SetThreadLocal : public ThreadLocalTesterBase {
+ public:
+  SetThreadLocal(TLPType* tlp, base::WaitableEvent* done)
+      : ThreadLocalTesterBase(tlp, done), val_(NULL) { }
+  ~SetThreadLocal() { }
+
+  void set_value(ThreadLocalTesterBase* val) { val_ = val; }
+
+  virtual void Run() {
+    DCHECK(!done_->IsSignaled());
+    tlp_->Set(val_);
+    done_->Signal();
+  }
+
+ private:
+  ThreadLocalTesterBase* val_;
+};
+
+class GetThreadLocal : public ThreadLocalTesterBase {
+ public:
+  GetThreadLocal(TLPType* tlp, base::WaitableEvent* done)
+      : ThreadLocalTesterBase(tlp, done), ptr_(NULL) { }
+  ~GetThreadLocal() { }
+
+  void set_ptr(ThreadLocalTesterBase** ptr) { ptr_ = ptr; }
+
+  virtual void Run() {
+    DCHECK(!done_->IsSignaled());
+    *ptr_ = tlp_->Get();
+    done_->Signal();
+  }
+
+ private:
+  ThreadLocalTesterBase** ptr_;
+};
+
+}  // namespace
+
+// In this test, we start 2 threads which will access a ThreadLocalPointer.  We
+// make sure the default is NULL, and the pointers are unique to the threads.
+TEST(ThreadLocalTest, Pointer) {
+  base::DelegateSimpleThreadPool tp1("ThreadLocalTest tp1", 1);
+  base::DelegateSimpleThreadPool tp2("ThreadLocalTest tp1", 1);
+  tp1.Start();
+  tp2.Start();
+
+  base::ThreadLocalPointer<ThreadLocalTesterBase> tlp;
+
+  static ThreadLocalTesterBase* const kBogusPointer =
+      reinterpret_cast<ThreadLocalTesterBase*>(0x1234);
+
+  ThreadLocalTesterBase* tls_val;
+  base::WaitableEvent done(true, false);
+
+  GetThreadLocal getter(&tlp, &done);
+  getter.set_ptr(&tls_val);
+
+  // Check that both threads defaulted to NULL.
+  tls_val = kBogusPointer;
+  done.Reset();
+  tp1.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(static_cast<ThreadLocalTesterBase*>(NULL), tls_val);
+
+  tls_val = kBogusPointer;
+  done.Reset();
+  tp2.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(static_cast<ThreadLocalTesterBase*>(NULL), tls_val);
+
+
+  SetThreadLocal setter(&tlp, &done);
+  setter.set_value(kBogusPointer);
+
+  // Have thread 1 set their pointer value to kBogusPointer.
+  done.Reset();
+  tp1.AddWork(&setter);
+  done.Wait();
+
+  tls_val = NULL;
+  done.Reset();
+  tp1.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(kBogusPointer, tls_val);
+
+  // Make sure thread 2 is still NULL
+  tls_val = kBogusPointer;
+  done.Reset();
+  tp2.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(static_cast<ThreadLocalTesterBase*>(NULL), tls_val);
+
+  // Set thread 2 to kBogusPointer + 1.
+  setter.set_value(kBogusPointer + 1);
+
+  done.Reset();
+  tp2.AddWork(&setter);
+  done.Wait();
+
+  tls_val = NULL;
+  done.Reset();
+  tp2.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(kBogusPointer + 1, tls_val);
+
+  // Make sure thread 1 is still kBogusPointer.
+  tls_val = NULL;
+  done.Reset();
+  tp1.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(kBogusPointer, tls_val);
+
+  tp1.JoinAll();
+  tp2.JoinAll();
+}
+
+TEST(ThreadLocalTest, Boolean) {
+  {
+    base::ThreadLocalBoolean tlb;
+    EXPECT_FALSE(tlb.Get());
+
+    tlb.Set(false);
+    EXPECT_FALSE(tlb.Get());
+
+    tlb.Set(true);
+    EXPECT_TRUE(tlb.Get());
+  }
+
+  // Our slot should have been freed, we're all reset.
+  {
+    base::ThreadLocalBoolean tlb;
+    EXPECT_FALSE(tlb.Get());
+  }
+}
+
+}  // namespace base
diff --git a/base/threading/thread_local_win.cc b/base/threading/thread_local_win.cc
new file mode 100644
index 0000000..56d3a3a
--- /dev/null
+++ b/base/threading/thread_local_win.cc
@@ -0,0 +1,42 @@
+// Copyright (c) 2010 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.
+
+#include "base/threading/thread_local.h"
+
+#include <windows.h>
+
+#include "base/logging.h"
+
+namespace base {
+
+namespace internal {
+
+// static
+void ThreadLocalPlatform::AllocateSlot(SlotType& slot) {
+  slot = TlsAlloc();
+  CHECK_NE(slot, TLS_OUT_OF_INDEXES);
+}
+
+// static
+void ThreadLocalPlatform::FreeSlot(SlotType& slot) {
+  if (!TlsFree(slot)) {
+    NOTREACHED() << "Failed to deallocate tls slot with TlsFree().";
+  }
+}
+
+// static
+void* ThreadLocalPlatform::GetValueFromSlot(SlotType& slot) {
+  return TlsGetValue(slot);
+}
+
+// static
+void ThreadLocalPlatform::SetValueInSlot(SlotType& slot, void* value) {
+  if (!TlsSetValue(slot, value)) {
+    LOG(FATAL) << "Failed to TlsSetValue().";
+  }
+}
+
+}  // namespace internal
+
+}  // namespace base