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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 09:22:09 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 09:22:09 +0000 |
commit | 43a97878ce14b72f0981164f87f2e35e14151312 (patch) | |
tree | 620249daf56c0258faa40cbdcf9cfba06de2a846 /security/sandbox/chromium/base/threading/thread_local.h | |
parent | Initial commit. (diff) | |
download | firefox-43a97878ce14b72f0981164f87f2e35e14151312.tar.xz firefox-43a97878ce14b72f0981164f87f2e35e14151312.zip |
Adding upstream version 110.0.1.upstream/110.0.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'security/sandbox/chromium/base/threading/thread_local.h')
-rw-r--r-- | security/sandbox/chromium/base/threading/thread_local.h | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/threading/thread_local.h b/security/sandbox/chromium/base/threading/thread_local.h new file mode 100644 index 0000000000..f9762050b6 --- /dev/null +++ b/security/sandbox/chromium/base/threading/thread_local.h @@ -0,0 +1,136 @@ +// Copyright (c) 2011 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 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. +// +// 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. +// +// In Android, the system TLS is limited. +// +// 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_ + +#include <memory> + +#include "base/logging.h" +#include "base/macros.h" +#include "base/threading/thread_local_internal.h" +#include "base/threading/thread_local_storage.h" + +namespace base { + +template <typename T> +class ThreadLocalPointer { + public: + ThreadLocalPointer() = default; + ~ThreadLocalPointer() = default; + + T* Get() const { return static_cast<T*>(slot_.Get()); } + + void Set(T* ptr) { + slot_.Set(const_cast<void*>(static_cast<const void*>(ptr))); + } + + private: + ThreadLocalStorage::Slot slot_; + + DISALLOW_COPY_AND_ASSIGN(ThreadLocalPointer<T>); +}; + +// A ThreadLocalOwnedPointer<T> is like a ThreadLocalPointer<T> except that +// pointers handed to it are owned and automatically deleted during their +// associated thread's exit phase (or when replaced if Set() is invoked multiple +// times on the same thread). +// The ThreadLocalOwnedPointer instance itself can only be destroyed when no +// threads, other than the one it is destroyed on, have remaining state set in +// it. Typically this means that ThreadLocalOwnedPointer instances are held in +// static storage or at the very least only recycled in the single-threaded +// phase between tests in the same process. +#if DCHECK_IS_ON() +template <typename T> +using ThreadLocalOwnedPointer = internal::CheckedThreadLocalOwnedPointer<T>; +#else // DCHECK_IS_ON() +template <typename T> +class ThreadLocalOwnedPointer { + public: + ThreadLocalOwnedPointer() = default; + + ~ThreadLocalOwnedPointer() { + // Assume that this thread is the only one with potential state left. This + // is verified in ~CheckedThreadLocalOwnedPointer(). + Set(nullptr); + } + + T* Get() const { return static_cast<T*>(slot_.Get()); } + + void Set(std::unique_ptr<T> ptr) { + delete Get(); + slot_.Set(const_cast<void*>(static_cast<const void*>(ptr.release()))); + } + + private: + static void DeleteTlsPtr(void* ptr) { delete static_cast<T*>(ptr); } + + ThreadLocalStorage::Slot slot_{&DeleteTlsPtr}; + + DISALLOW_COPY_AND_ASSIGN(ThreadLocalOwnedPointer<T>); +}; +#endif // DCHECK_IS_ON() + +class ThreadLocalBoolean { + public: + ThreadLocalBoolean() = default; + ~ThreadLocalBoolean() = default; + + bool Get() const { return tlp_.Get() != nullptr; } + + void Set(bool val) { tlp_.Set(val ? this : nullptr); } + + private: + ThreadLocalPointer<void> tlp_; + + DISALLOW_COPY_AND_ASSIGN(ThreadLocalBoolean); +}; + +} // namespace base + +#endif // BASE_THREADING_THREAD_LOCAL_H_ |