compile successfully

at_exit.cc

@@ -0,0 +1,109 @@
+// 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.
+
+#include "base/at_exit.h"
+
+#include <stddef.h>
+#include <ostream>
+#include <utility>
+
+#include "base/bind.h"
+#include "base/callback.h"
+// #include "base/logging.h"
+
+namespace base {
+
+// Keep a stack of registered AtExitManagers.  We always operate on the most
+// recent, and we should never have more than one outside of testing (for a
+// statically linked version of this library).  Testing may use the shadow
+// version of the constructor, and if we are building a dynamic library we may
+// end up with multiple AtExitManagers on the same process.  We don't protect
+// this for thread-safe access, since it will only be modified in testing.
+static AtExitManager* g_top_manager = nullptr;
+
+static bool g_disable_managers = false;
+
+AtExitManager::AtExitManager()
+    : processing_callbacks_(false), next_manager_(g_top_manager) {
+// If multiple modules instantiate AtExitManagers they'll end up living in this
+// module... they have to coexist.
+#if !defined(COMPONENT_BUILD)
+  // DCHECK(!g_top_manager);
+#endif
+  g_top_manager = this;
+}
+
+AtExitManager::~AtExitManager() {
+  if (!g_top_manager) {
+    // NOTREACHED() << "Tried to ~AtExitManager without an AtExitManager";
+    return;
+  }
+  // DCHECK_EQ(this, g_top_manager);
+
+  if (!g_disable_managers)
+    ProcessCallbacksNow();
+  g_top_manager = next_manager_;
+}
+
+// static
+void AtExitManager::RegisterCallback(AtExitCallbackType func, void* param) {
+  // DCHECK(func);
+  RegisterTask(base::Bind(func, param));
+}
+
+// static
+void AtExitManager::RegisterTask(base::Closure task) {
+  if (!g_top_manager) {
+    // NOTREACHED() << "Tried to RegisterCallback without an AtExitManager";
+    return;
+  }
+
+  AutoLock lock(g_top_manager->lock_);
+  // DCHECK(!g_top_manager->processing_callbacks_);
+  g_top_manager->stack_.push(std::move(task));
+}
+
+// static
+void AtExitManager::ProcessCallbacksNow() {
+  if (!g_top_manager) {
+    // NOTREACHED() << "Tried to ProcessCallbacksNow without an AtExitManager";
+    return;
+  }
+
+  // Callbacks may try to add new callbacks, so run them without holding
+  // |lock_|. This is an error and caught by the DCHECK in RegisterTask(), but
+  // handle it gracefully in release builds so we don't deadlock.
+  base::stack<base::Closure> tasks;
+  {
+    AutoLock lock(g_top_manager->lock_);
+    tasks.swap(g_top_manager->stack_);
+    g_top_manager->processing_callbacks_ = true;
+  }
+
+  // Relax the cross-thread access restriction to non-thread-safe RefCount.
+  // It's safe since all other threads should be terminated at this point.
+  ScopedAllowCrossThreadRefCountAccess allow_cross_thread_ref_count_access;
+
+  while (!tasks.empty()) {
+    base::Closure task = tasks.top();
+    task.Run();
+    tasks.pop();
+  }
+
+  // Expect that all callbacks have been run.
+  // DCHECK(g_top_manager->stack_.empty());
+}
+
+void AtExitManager::DisableAllAtExitManagers() {
+  AutoLock lock(g_top_manager->lock_);
+  g_disable_managers = true;
+}
+
+AtExitManager::AtExitManager(bool shadow)
+    : processing_callbacks_(false), next_manager_(g_top_manager) {
+  // DCHECK(shadow || !g_top_manager);
+  g_top_manager = this;
+}
+
+}  // namespace base

atomicops.h

@@ -159,3 +159,237 @@ Atomic64 Release_Load(volatile const Atomic64* ptr);
 // #endif
 
 #endif  // BASE_ATOMICOPS_H_
+
+
+// NOTE: copied from atomicops_internals_portable
+// Copyright (c) 2014 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.
+
+// This file is an internal atomic implementation, use atomicops.h instead.
+//
+// This implementation uses C++11 atomics' member functions. The code base is
+// currently written assuming atomicity revolves around accesses instead of
+// C++11's memory locations. The burden is on the programmer to ensure that all
+// memory locations accessed atomically are never accessed non-atomically (tsan
+// should help with this).
+//
+// TODO(jfb) Modify the atomicops.h API and user code to declare atomic
+//           locations as truly atomic. See the static_assert below.
+//
+// Of note in this implementation:
+//  * All NoBarrier variants are implemented as relaxed.
+//  * All Barrier variants are implemented as sequentially-consistent.
+//  * Compare exchange's failure ordering is always the same as the success one
+//    (except for release, which fails as relaxed): using a weaker ordering is
+//    only valid under certain uses of compare exchange.
+//  * Acquire store doesn't exist in the C11 memory model, it is instead
+//    implemented as a relaxed store followed by a sequentially consistent
+//    fence.
+//  * Release load doesn't exist in the C11 memory model, it is instead
+//    implemented as sequentially consistent fence followed by a relaxed load.
+//  * Atomic increment is expected to return the post-incremented value, whereas
+//    C11 fetch add returns the previous value. The implementation therefore
+//    needs to increment twice (which the compiler should be able to detect and
+//    optimize).
+
+#ifndef BASE_ATOMICOPS_INTERNALS_PORTABLE_H_
+#define BASE_ATOMICOPS_INTERNALS_PORTABLE_H_
+
+#include "base/atomicops.h"
+
+#include <atomic>
+
+#include "build/build_config.h"
+
+namespace base {
+namespace subtle {
+
+// This implementation is transitional and maintains the original API for
+// atomicops.h. This requires casting memory locations to the atomic types, and
+// assumes that the API and the C++11 implementation are layout-compatible,
+// which isn't true for all implementations or hardware platforms. The static
+// assertion should detect this issue, were it to fire then this header
+// shouldn't be used.
+//
+// TODO(jfb) If this header manages to stay committed then the API should be
+//           modified, and all call sites updated.
+typedef volatile std::atomic<Atomic32>* AtomicLocation32;
+static_assert(sizeof(*(AtomicLocation32) nullptr) == sizeof(Atomic32),
+              "incompatible 32-bit atomic layout");
+
+inline void MemoryBarrier() {
+#if defined(__GLIBCXX__)
+  // Work around libstdc++ bug 51038 where atomic_thread_fence was declared but
+  // not defined, leading to the linker complaining about undefined references.
+  __atomic_thread_fence(std::memory_order_seq_cst);
+#else
+  std::atomic_thread_fence(std::memory_order_seq_cst);
+#endif
+}
+
+inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+                                         Atomic32 old_value,
+                                         Atomic32 new_value) {
+  ((AtomicLocation32)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_relaxed,
+                                std::memory_order_relaxed);
+  return old_value;
+}
+
+inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
+                                         Atomic32 new_value) {
+  return ((AtomicLocation32)ptr)
+      ->exchange(new_value, std::memory_order_relaxed);
+}
+
+inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
+                                          Atomic32 increment) {
+  return increment +
+         ((AtomicLocation32)ptr)
+             ->fetch_add(increment, std::memory_order_relaxed);
+}
+
+inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+                                        Atomic32 increment) {
+  return increment + ((AtomicLocation32)ptr)->fetch_add(increment);
+}
+
+inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
+                                       Atomic32 old_value,
+                                       Atomic32 new_value) {
+  ((AtomicLocation32)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_acquire,
+                                std::memory_order_acquire);
+  return old_value;
+}
+
+inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
+                                       Atomic32 old_value,
+                                       Atomic32 new_value) {
+  ((AtomicLocation32)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_release,
+                                std::memory_order_relaxed);
+  return old_value;
+}
+
+inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
+  ((AtomicLocation32)ptr)->store(value, std::memory_order_relaxed);
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+  ((AtomicLocation32)ptr)->store(value, std::memory_order_relaxed);
+  MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
+  ((AtomicLocation32)ptr)->store(value, std::memory_order_release);
+}
+
+inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
+  return ((AtomicLocation32)ptr)->load(std::memory_order_relaxed);
+}
+
+inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
+  return ((AtomicLocation32)ptr)->load(std::memory_order_acquire);
+}
+
+inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
+  MemoryBarrier();
+  return ((AtomicLocation32)ptr)->load(std::memory_order_relaxed);
+}
+
+#if defined(ARCH_CPU_64_BITS)
+
+typedef volatile std::atomic<Atomic64>* AtomicLocation64;
+static_assert(sizeof(*(AtomicLocation64) nullptr) == sizeof(Atomic64),
+              "incompatible 64-bit atomic layout");
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+                                         Atomic64 old_value,
+                                         Atomic64 new_value) {
+  ((AtomicLocation64)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_relaxed,
+                                std::memory_order_relaxed);
+  return old_value;
+}
+
+inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
+                                         Atomic64 new_value) {
+  return ((AtomicLocation64)ptr)
+      ->exchange(new_value, std::memory_order_relaxed);
+}
+
+inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
+                                          Atomic64 increment) {
+  return increment +
+         ((AtomicLocation64)ptr)
+             ->fetch_add(increment, std::memory_order_relaxed);
+}
+
+inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
+                                        Atomic64 increment) {
+  return increment + ((AtomicLocation64)ptr)->fetch_add(increment);
+}
+
+inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  ((AtomicLocation64)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_acquire,
+                                std::memory_order_acquire);
+  return old_value;
+}
+
+inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  ((AtomicLocation64)ptr)
+      ->compare_exchange_strong(old_value,
+                                new_value,
+                                std::memory_order_release,
+                                std::memory_order_relaxed);
+  return old_value;
+}
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+  ((AtomicLocation64)ptr)->store(value, std::memory_order_relaxed);
+}
+
+inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
+  ((AtomicLocation64)ptr)->store(value, std::memory_order_relaxed);
+  MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
+  ((AtomicLocation64)ptr)->store(value, std::memory_order_release);
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+  return ((AtomicLocation64)ptr)->load(std::memory_order_relaxed);
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
+  return ((AtomicLocation64)ptr)->load(std::memory_order_acquire);
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
+  MemoryBarrier();
+  return ((AtomicLocation64)ptr)->load(std::memory_order_relaxed);
+}
+
+#endif  // defined(ARCH_CPU_64_BITS)
+}  // namespace subtle
+}  // namespace base
+
+#endif  // BASE_ATOMICOPS_INTERNALS_PORTABLE_H_