81 lines
2.3 KiB
C++
81 lines
2.3 KiB
C++
// Copyright 2019 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_THREADING_THREAD_LOCAL_INTERNAL_H_
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#define BASE_THREADING_THREAD_LOCAL_INTERNAL_H_
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#if DCHECK_IS_ON()
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#include <atomic>
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#include <memory>
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#include "base/macros.h"
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#include "base/threading/thread_local_storage.h"
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namespace base {
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namespace internal {
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// A version of ThreadLocalOwnedPointer which verifies that it's only destroyed
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// when no threads, other than the one it is destroyed on, have remaining state
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// set in it. A ThreadLocalOwnedPointer instance being destroyed too early would
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// result in leaks per unregistering the TLS slot (and thus the DeleteTlsPtr
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// hook).
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template <typename T>
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class CheckedThreadLocalOwnedPointer {
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public:
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CheckedThreadLocalOwnedPointer() = default;
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~CheckedThreadLocalOwnedPointer() {
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Set(nullptr);
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DCHECK_EQ(num_assigned_threads_.load(std::memory_order_relaxed), 0)
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<< "Memory leak: Must join all threads or release all associated "
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"thread-local slots before ~ThreadLocalOwnedPointer";
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}
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T* Get() const {
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PtrTracker* const ptr_tracker = static_cast<PtrTracker*>(slot_.Get());
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return ptr_tracker ? ptr_tracker->ptr_.get() : nullptr;
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}
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void Set(std::unique_ptr<T> ptr) {
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delete static_cast<PtrTracker*>(slot_.Get());
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if (ptr)
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slot_.Set(new PtrTracker(this, std::move(ptr)));
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else
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slot_.Set(nullptr);
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}
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private:
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struct PtrTracker {
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public:
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PtrTracker(CheckedThreadLocalOwnedPointer<T>* outer, std::unique_ptr<T> ptr)
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: outer_(outer), ptr_(std::move(ptr)) {
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outer_->num_assigned_threads_.fetch_add(1, std::memory_order_relaxed);
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}
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~PtrTracker() {
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outer_->num_assigned_threads_.fetch_sub(1, std::memory_order_relaxed);
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}
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CheckedThreadLocalOwnedPointer<T>* const outer_;
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const std::unique_ptr<T> ptr_;
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};
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static void DeleteTlsPtr(void* ptr) { delete static_cast<PtrTracker*>(ptr); }
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ThreadLocalStorage::Slot slot_{&DeleteTlsPtr};
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std::atomic_int num_assigned_threads_{0};
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DISALLOW_COPY_AND_ASSIGN(CheckedThreadLocalOwnedPointer<T>);
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};
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} // namespace internal
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} // namespace base
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#endif // DCHECK_IS_ON()
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#endif // BASE_THREADING_THREAD_LOCAL_INTERNAL_H_
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