base: Use LazyInstanceTraits instead of SharedState class for discardable memory.

base/memory/discardable_memory_mach.cc

 // Copyright 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.
 
 #include "base/memory/discardable_memory_mach.h"
 
 #include <mach/mach.h>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/mac/mach_logging.h"
 
 namespace base {
 namespace {
 
 // For Mach, have the DiscardableMemoryManager trigger userspace eviction when
 // address space usage gets too high (e.g. 512 MBytes).
 const size_t kMachMemoryLimit = 512 * 1024 * 1024;
 
-struct SharedState {
-  SharedState()
-      : manager(kMachMemoryLimit, kMachMemoryLimit, TimeDelta::Max()) {}
+// internal::DiscardableMemoryManager has an explicit constructor that takes
+// a number of memory limit parameters. The LeakyLazyInstanceTraits doesn't
+// handle the case. Thus, we need our own class here.
+struct DiscardableMemoryManagerLazyInstanceTraits {
+  // Leaky as discardable memory clients can use this after the exit handler
+  // has been called.
+  static const bool kRegisterOnExit = false;
+#ifndef NDEBUG
+  static const bool kAllowedToAccessOnNonjoinableThread = true;
+#endif
 
-  internal::DiscardableMemoryManager manager;
+  static internal::DiscardableMemoryManager* New(void* instance) {
+    return new (instance) internal::DiscardableMemoryManager(
+        kMachMemoryLimit, kMachMemoryLimit, TimeDelta::Max());
+  }
+  static void Delete(internal::DiscardableMemoryManager* instance) {
+    instance->~DiscardableMemoryManager();
+  }
 };
-LazyInstance<SharedState>::Leaky g_shared_state = LAZY_INSTANCE_INITIALIZER;
+
+LazyInstance<internal::DiscardableMemoryManager,
+             DiscardableMemoryManagerLazyInstanceTraits>
+    g_manager = LAZY_INSTANCE_INITIALIZER;
 
 // The VM subsystem allows tagging of memory and 240-255 is reserved for
 // application use (see mach/vm_statistics.h). Pick 252 (after chromium's atomic
 // weight of ~52).
 const int kDiscardableMemoryTag = VM_MAKE_TAG(252);
 
 }  // namespace
 
 namespace internal {
 
 DiscardableMemoryMach::DiscardableMemoryMach(size_t bytes)
     : memory_(0, 0), bytes_(mach_vm_round_page(bytes)), is_locked_(false) {
-  g_shared_state.Pointer()->manager.Register(this, bytes);
+  g_manager.Pointer()->Register(this, bytes);
 }
 
 DiscardableMemoryMach::~DiscardableMemoryMach() {
   if (is_locked_)
     Unlock();
-  g_shared_state.Pointer()->manager.Unregister(this);
+  g_manager.Pointer()->Unregister(this);
 }
 
 // static
 void DiscardableMemoryMach::PurgeForTesting() {
   int state = 0;
   vm_purgable_control(mach_task_self(), 0, VM_PURGABLE_PURGE_ALL, &state);
 }
 
 bool DiscardableMemoryMach::Initialize() {
   return Lock() != DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
 }
 
 DiscardableMemoryLockStatus DiscardableMemoryMach::Lock() {
   DCHECK(!is_locked_);
 
   bool purged = false;
-  if (!g_shared_state.Pointer()->manager.AcquireLock(this, &purged))
+  if (!g_manager.Pointer()->AcquireLock(this, &purged))
     return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
 
   is_locked_ = true;
   return purged ? DISCARDABLE_MEMORY_LOCK_STATUS_PURGED
                 : DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
 }
 
 void DiscardableMemoryMach::Unlock() {
   DCHECK(is_locked_);
-  g_shared_state.Pointer()->manager.ReleaseLock(this);
+  g_manager.Pointer()->ReleaseLock(this);
   is_locked_ = false;
 }
 
 void* DiscardableMemoryMach::Memory() const {
   DCHECK(is_locked_);
   return reinterpret_cast<void*>(memory_.address());
 }
 
 bool DiscardableMemoryMach::AllocateAndAcquireLock() {
   kern_return_t ret;
@@ skipping 48 matching lines @@
   MACH_DCHECK(ret == KERN_SUCCESS, ret) << "vm_protect";
 #endif
 }
 
 void DiscardableMemoryMach::Purge() {
   memory_.reset();
 }
 
 }  // namespace internal
 }  // namespace base