1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/security/sandbox/chromium/base/threading/thread_local.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,128 @@
1.4 +// Copyright (c) 2011 The Chromium Authors. All rights reserved.
1.5 +// Use of this source code is governed by a BSD-style license that can be
1.6 +// found in the LICENSE file.
1.7 +
1.8 +// WARNING: Thread local storage is a bit tricky to get right. Please make
1.9 +// sure that this is really the proper solution for what you're trying to
1.10 +// achieve. Don't prematurely optimize, most likely you can just use a Lock.
1.11 +//
1.12 +// These classes implement a wrapper around the platform's TLS storage
1.13 +// mechanism. On construction, they will allocate a TLS slot, and free the
1.14 +// TLS slot on destruction. No memory management (creation or destruction) is
1.15 +// handled. This means for uses of ThreadLocalPointer, you must correctly
1.16 +// manage the memory yourself, these classes will not destroy the pointer for
1.17 +// you. There are no at-thread-exit actions taken by these classes.
1.18 +//
1.19 +// ThreadLocalPointer<Type> wraps a Type*. It performs no creation or
1.20 +// destruction, so memory management must be handled elsewhere. The first call
1.21 +// to Get() on a thread will return NULL. You can update the pointer with a
1.22 +// call to Set().
1.23 +//
1.24 +// ThreadLocalBoolean wraps a bool. It will default to false if it has never
1.25 +// been set otherwise with Set().
1.26 +//
1.27 +// Thread Safety: An instance of ThreadLocalStorage is completely thread safe
1.28 +// once it has been created. If you want to dynamically create an instance,
1.29 +// you must of course properly deal with safety and race conditions. This
1.30 +// means a function-level static initializer is generally inappropiate.
1.31 +//
1.32 +// Example usage:
1.33 +// // My class is logically attached to a single thread. We cache a pointer
1.34 +// // on the thread it was created on, so we can implement current().
1.35 +// MyClass::MyClass() {
1.36 +// DCHECK(Singleton<ThreadLocalPointer<MyClass> >::get()->Get() == NULL);
1.37 +// Singleton<ThreadLocalPointer<MyClass> >::get()->Set(this);
1.38 +// }
1.39 +//
1.40 +// MyClass::~MyClass() {
1.41 +// DCHECK(Singleton<ThreadLocalPointer<MyClass> >::get()->Get() != NULL);
1.42 +// Singleton<ThreadLocalPointer<MyClass> >::get()->Set(NULL);
1.43 +// }
1.44 +//
1.45 +// // Return the current MyClass associated with the calling thread, can be
1.46 +// // NULL if there isn't a MyClass associated.
1.47 +// MyClass* MyClass::current() {
1.48 +// return Singleton<ThreadLocalPointer<MyClass> >::get()->Get();
1.49 +// }
1.50 +
1.51 +#ifndef BASE_THREADING_THREAD_LOCAL_H_
1.52 +#define BASE_THREADING_THREAD_LOCAL_H_
1.53 +
1.54 +#include "base/base_export.h"
1.55 +#include "base/basictypes.h"
1.56 +
1.57 +#if defined(OS_POSIX)
1.58 +#include <pthread.h>
1.59 +#endif
1.60 +
1.61 +namespace base {
1.62 +
1.63 +namespace internal {
1.64 +
1.65 +// Helper functions that abstract the cross-platform APIs. Do not use directly.
1.66 +struct BASE_EXPORT ThreadLocalPlatform {
1.67 +#if defined(OS_WIN)
1.68 + typedef unsigned long SlotType;
1.69 +#elif defined(OS_POSIX)
1.70 + typedef pthread_key_t SlotType;
1.71 +#endif
1.72 +
1.73 + static void AllocateSlot(SlotType& slot);
1.74 + static void FreeSlot(SlotType& slot);
1.75 + static void* GetValueFromSlot(SlotType& slot);
1.76 + static void SetValueInSlot(SlotType& slot, void* value);
1.77 +};
1.78 +
1.79 +} // namespace internal
1.80 +
1.81 +template <typename Type>
1.82 +class ThreadLocalPointer {
1.83 + public:
1.84 + ThreadLocalPointer() : slot_() {
1.85 + internal::ThreadLocalPlatform::AllocateSlot(slot_);
1.86 + }
1.87 +
1.88 + ~ThreadLocalPointer() {
1.89 + internal::ThreadLocalPlatform::FreeSlot(slot_);
1.90 + }
1.91 +
1.92 + Type* Get() {
1.93 + return static_cast<Type*>(
1.94 + internal::ThreadLocalPlatform::GetValueFromSlot(slot_));
1.95 + }
1.96 +
1.97 + void Set(Type* ptr) {
1.98 + internal::ThreadLocalPlatform::SetValueInSlot(
1.99 + slot_, const_cast<void*>(static_cast<const void*>(ptr)));
1.100 + }
1.101 +
1.102 + private:
1.103 + typedef internal::ThreadLocalPlatform::SlotType SlotType;
1.104 +
1.105 + SlotType slot_;
1.106 +
1.107 + DISALLOW_COPY_AND_ASSIGN(ThreadLocalPointer<Type>);
1.108 +};
1.109 +
1.110 +class ThreadLocalBoolean {
1.111 + public:
1.112 + ThreadLocalBoolean() { }
1.113 + ~ThreadLocalBoolean() { }
1.114 +
1.115 + bool Get() {
1.116 + return tlp_.Get() != NULL;
1.117 + }
1.118 +
1.119 + void Set(bool val) {
1.120 + tlp_.Set(val ? this : NULL);
1.121 + }
1.122 +
1.123 + private:
1.124 + ThreadLocalPointer<void> tlp_;
1.125 +
1.126 + DISALLOW_COPY_AND_ASSIGN(ThreadLocalBoolean);
1.127 +};
1.128 +
1.129 +} // namespace base
1.130 +
1.131 +#endif // BASE_THREADING_THREAD_LOCAL_H_
