Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(655)

Unified Diff: base/threading/thread_local.h

Issue 1743693002: Revert of Refactor thread_local.h's TLS Implementation to use ThreadLocalStorage (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Created 4 years, 10 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View side-by-side diff with in-line comments
Download patch
« no previous file with comments | « base/base.gypi ('k') | base/threading/thread_local_android.cc » ('j') | no next file with comments »
Expand Comments ('e') | Collapse Comments ('c') | Show Comments Hide Comments ('s')
Index: base/threading/thread_local.h
diff --git a/base/threading/thread_local.h b/base/threading/thread_local.h
index cad9add3a9ca344ec03b75a8be150370d509ba1a..f40420cd2f8b8276e643b08ab294e8bdfba92b24 100644
--- a/base/threading/thread_local.h
+++ b/base/threading/thread_local.h
@@ -2,34 +2,35 @@
// 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.
+// 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 ThreadLocalStorage::Slot. 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.
+// 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().
+// 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
+// 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.
+// 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.
//
-// In Android, the system TLS is limited.
+// In Android, the system TLS is limited, the implementation is backed with
+// ThreadLocalStorage.
//
// Example usage:
-// // My class is logically attached to a single thread. We cache a pointer
+// // 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);
@@ -50,42 +51,76 @@
#ifndef BASE_THREADING_THREAD_LOCAL_H_
#define BASE_THREADING_THREAD_LOCAL_H_
+#include "base/base_export.h"
#include "base/macros.h"
#include "base/threading/thread_local_storage.h"
+#include "build/build_config.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 BASE_EXPORT ThreadLocalPlatform {
+#if defined(OS_WIN)
+ typedef unsigned long SlotType;
+#elif defined(OS_ANDROID)
+ typedef ThreadLocalStorage::StaticSlot 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() = default;
- ~ThreadLocalPointer() = default;
+ ThreadLocalPointer() : slot_() {
+ internal::ThreadLocalPlatform::AllocateSlot(&slot_);
+ }
+
+ ~ThreadLocalPointer() {
+ internal::ThreadLocalPlatform::FreeSlot(slot_);
+ }
Type* Get() {
- return static_cast<Type*>(slot_.Get());
+ return static_cast<Type*>(
+ internal::ThreadLocalPlatform::GetValueFromSlot(slot_));
}
void Set(Type* ptr) {
- slot_.Set(const_cast<void*>(static_cast<const void*>(ptr)));
+ internal::ThreadLocalPlatform::SetValueInSlot(
+ slot_, const_cast<void*>(static_cast<const void*>(ptr)));
}
private:
- ThreadLocalStorage::Slot slot_;
+ typedef internal::ThreadLocalPlatform::SlotType SlotType;
+
+ SlotType slot_;
DISALLOW_COPY_AND_ASSIGN(ThreadLocalPointer<Type>);
};
class ThreadLocalBoolean {
public:
- ThreadLocalBoolean() = default;
- ~ThreadLocalBoolean() = default;
+ ThreadLocalBoolean() {}
+ ~ThreadLocalBoolean() {}
bool Get() {
- return tlp_.Get() != nullptr;
+ return tlp_.Get() != NULL;
}
void Set(bool val) {
- tlp_.Set(val ? this : nullptr);
+ tlp_.Set(val ? this : NULL);
}
private:
« no previous file with comments | « base/base.gypi ('k') | base/threading/thread_local_android.cc » ('j') | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698