base: Refactor DiscardableMemoryManager for use with different type of allocations.

base/memory/discardable_memory_manager.cc

Index: base/memory/discardable_memory_manager.cc
diff --git a/base/memory/discardable_memory_manager.cc b/base/memory/discardable_memory_manager.cc
index fc263521015340b4687cfddc12e040f1746faf7f..ea5e45f56a55b543c71521fe305cdfd9948c2350 100644
--- a/base/memory/discardable_memory_manager.cc
+++ b/base/memory/discardable_memory_manager.cc
@@ -4,114 +4,89 @@
 
 #include "base/memory/discardable_memory_manager.h"
 
-#include "base/bind.h"
 #include "base/containers/hash_tables.h"
 #include "base/containers/mru_cache.h"
 #include "base/debug/trace_event.h"
 #include "base/synchronization/lock.h"
-#include "base/sys_info.h"
 
 namespace base {
 namespace internal {
 
-namespace {
+DiscardableMemoryManager::AllocationInfo::AllocationInfo(size_t bytes)
+    : bytes(bytes), locked(false) {}
 
-// This is admittedly pretty magical. It's approximately enough memory for four
-// 2560x1600 images.
-static const size_t kDefaultDiscardableMemoryLimit = 64 * 1024 * 1024;
-static const size_t kDefaultBytesToKeepUnderModeratePressure =
-    kDefaultDiscardableMemoryLimit / 4;
+DiscardableMemoryManager::AllocationInfo::~AllocationInfo() {}
 
-}  // namespace
-
-DiscardableMemoryManager::DiscardableMemoryManager()
-    : allocations_(AllocationMap::NO_AUTO_EVICT),
+DiscardableMemoryManager::DiscardableMemoryManager(
+    DiscardableMemoryAllocation::Factory* allocation_factory,
+    size_t discardable_memory_limit)
+    : allocation_factory_(allocation_factory),
+      next_allocation_id_(0),
+      allocations_(AllocationMap::NO_AUTO_EVICT),
       bytes_allocated_(0),
-      discardable_memory_limit_(kDefaultDiscardableMemoryLimit),
-      bytes_to_keep_under_moderate_pressure_(
-          kDefaultBytesToKeepUnderModeratePressure) {
-}
+      discardable_memory_limit_(discardable_memory_limit) {}
 
 DiscardableMemoryManager::~DiscardableMemoryManager() {
   DCHECK(allocations_.empty());
   DCHECK_EQ(0u, bytes_allocated_);
 }
 
-void DiscardableMemoryManager::RegisterMemoryPressureListener() {
-  AutoLock lock(lock_);
-  DCHECK(base::MessageLoop::current());
-  DCHECK(!memory_pressure_listener_);
-  memory_pressure_listener_.reset(
-      new MemoryPressureListener(
-          base::Bind(&DiscardableMemoryManager::OnMemoryPressure,
-                     Unretained(this))));
-}
-
-void DiscardableMemoryManager::UnregisterMemoryPressureListener() {
-  AutoLock lock(lock_);
-  DCHECK(memory_pressure_listener_);
-  memory_pressure_listener_.reset();
-}
-
 void DiscardableMemoryManager::SetDiscardableMemoryLimit(size_t bytes) {
   AutoLock lock(lock_);
   discardable_memory_limit_ = bytes;
   EnforcePolicyWithLockAcquired();
 }
 
-void DiscardableMemoryManager::SetBytesToKeepUnderModeratePressure(
+DiscardableMemoryManager::AllocationId DiscardableMemoryManager::Register(
     size_t bytes) {
   AutoLock lock(lock_);
-  bytes_to_keep_under_moderate_pressure_ = bytes;
-}
-
-void DiscardableMemoryManager::Register(
-    const DiscardableMemory* discardable, size_t bytes) {
-  AutoLock lock(lock_);
+  AllocationId allocation_id = next_allocation_id_++;
+  if (next_allocation_id_ == INT_MAX)
+    next_allocation_id_ = 1;
   // A registered memory listener is currently required. This DCHECK can be
   // moved or removed if we decide that it's useful to relax this condition.
   // TODO(reveman): Enable this DCHECK when skia and blink are able to
   // register memory pressure listeners. crbug.com/333907
   // DCHECK(memory_pressure_listener_);
-  DCHECK(allocations_.Peek(discardable) == allocations_.end());
-  allocations_.Put(discardable, Allocation(bytes));
+  DCHECK(allocations_.Peek(allocation_id) == allocations_.end());
+  allocations_.Put(allocation_id, AllocationInfo(bytes));
+  return allocation_id;
 }
 
-void DiscardableMemoryManager::Unregister(
-    const DiscardableMemory* discardable) {
+void DiscardableMemoryManager::Unregister(AllocationId allocation_id) {
   AutoLock lock(lock_);
-  AllocationMap::iterator it = allocations_.Peek(discardable);
+  AllocationMap::iterator it = allocations_.Peek(allocation_id);
   if (it == allocations_.end())
     return;
 
-  if (it->second.memory) {
+  if (it->second.allocation.get()) {
     size_t bytes = it->second.bytes;
     DCHECK_LE(bytes, bytes_allocated_);
     bytes_allocated_ -= bytes;
-    free(it->second.memory);
+    it->second.allocation.reset();
   }
   allocations_.Erase(it);
 }
 
-scoped_ptr<uint8, FreeDeleter> DiscardableMemoryManager::Acquire(
-    const DiscardableMemory* discardable,
-    bool* purged) {
+void* DiscardableMemoryManager::Lock(AllocationId allocation_id, bool* purged) {
   AutoLock lock(lock_);
   // NB: |allocations_| is an MRU cache, and use of |Get| here updates that
   // cache.
-  AllocationMap::iterator it = allocations_.Get(discardable);
+  AllocationMap::iterator it = allocations_.Get(allocation_id);
   CHECK(it != allocations_.end());
 
-  if (it->second.memory) {
-    scoped_ptr<uint8, FreeDeleter> memory(it->second.memory);
-    it->second.memory = NULL;
-    *purged = false;
-    return memory.Pass();
+  if (it->second.allocation.get()) {
+    DiscardableMemoryAllocation* allocation = it->second.allocation.get();
+
+    DCHECK(!it->second.locked);
+    it->second.locked = true;
+    *purged = !allocation->Lock();
+    return allocation->Memory();
   }
 
   size_t bytes = it->second.bytes;
   if (!bytes)
-    return scoped_ptr<uint8, FreeDeleter>();
+    return NULL;
 
   if (discardable_memory_limit_) {
     size_t limit = 0;
@@ -123,49 +98,51 @@ scoped_ptr<uint8, FreeDeleter> DiscardableMemoryManager::Acquire(
 
   // Check for overflow.
   if (std::numeric_limits<size_t>::max() - bytes < bytes_allocated_)
-    return scoped_ptr<uint8, FreeDeleter>();
+    return NULL;
 
-  scoped_ptr<uint8, FreeDeleter> memory(static_cast<uint8*>(malloc(bytes)));
-  if (!memory)
-    return scoped_ptr<uint8, FreeDeleter>();
+  linked_ptr<DiscardableMemoryAllocation> allocation(
+      allocation_factory_->CreateLockedAllocation(bytes).release());
+  if (!allocation.get())
+    return NULL;
 
+  it->second.allocation = allocation;
+  it->second.locked = true;
   bytes_allocated_ += bytes;
   *purged = true;
-  return memory.Pass();
+  return allocation->Memory();
 }
 
-void DiscardableMemoryManager::Release(
-    const DiscardableMemory* discardable,
-    scoped_ptr<uint8, FreeDeleter> memory) {
+void DiscardableMemoryManager::Unlock(AllocationId allocation_id) {
   AutoLock lock(lock_);
   // NB: |allocations_| is an MRU cache, and use of |Get| here updates that
   // cache.
-  AllocationMap::iterator it = allocations_.Get(discardable);
+  AllocationMap::iterator it = allocations_.Get(allocation_id);
   CHECK(it != allocations_.end());
 
-  DCHECK(!it->second.memory);
-  it->second.memory = memory.release();
-
+  DCHECK(it->second.allocation.get());
+  DCHECK(it->second.locked);
+  it->second.locked = false;
+  it->second.allocation->Unlock();
   EnforcePolicyWithLockAcquired();
 }
 
-void DiscardableMemoryManager::PurgeAll() {
+void DiscardableMemoryManager::PurgeUntilUsageIsWithin(size_t limit) {
   AutoLock lock(lock_);
-  PurgeLRUWithLockAcquiredUntilUsageIsWithin(0);
+  PurgeLRUWithLockAcquiredUntilUsageIsWithin(limit);
 }
 
 bool DiscardableMemoryManager::IsRegisteredForTest(
-    const DiscardableMemory* discardable) const {
+    AllocationId allocation_id) const {
   AutoLock lock(lock_);
-  AllocationMap::const_iterator it = allocations_.Peek(discardable);
+  AllocationMap::const_iterator it = allocations_.Peek(allocation_id);
   return it != allocations_.end();
 }
 
 bool DiscardableMemoryManager::CanBePurgedForTest(
-    const DiscardableMemory* discardable) const {
+    AllocationId allocation_id) const {
   AutoLock lock(lock_);
-  AllocationMap::const_iterator it = allocations_.Peek(discardable);
-  return it != allocations_.end() && it->second.memory;
+  AllocationMap::const_iterator it = allocations_.Peek(allocation_id);
+  return it != allocations_.end() && !it->second.locked;
 }
 
 size_t DiscardableMemoryManager::GetBytesAllocatedForTest() const {
@@ -173,27 +150,6 @@ size_t DiscardableMemoryManager::GetBytesAllocatedForTest() const {
   return bytes_allocated_;
 }
 
-void DiscardableMemoryManager::OnMemoryPressure(
-    MemoryPressureListener::MemoryPressureLevel pressure_level) {
-  switch (pressure_level) {
-    case MemoryPressureListener::MEMORY_PRESSURE_MODERATE:
-      Purge();
-      return;
-    case MemoryPressureListener::MEMORY_PRESSURE_CRITICAL:
-      PurgeAll();
-      return;
-  }
-
-  NOTREACHED();
-}
-
-void DiscardableMemoryManager::Purge() {
-  AutoLock lock(lock_);
-
-  PurgeLRUWithLockAcquiredUntilUsageIsWithin(
-      bytes_to_keep_under_moderate_pressure_);
-}
-
 void DiscardableMemoryManager::PurgeLRUWithLockAcquiredUntilUsageIsWithin(
     size_t limit) {
   TRACE_EVENT1(
@@ -208,14 +164,15 @@ void DiscardableMemoryManager::PurgeLRUWithLockAcquiredUntilUsageIsWithin(
        ++it) {
     if (bytes_allocated_ <= limit)
       break;
-    if (!it->second.memory)
+    if (!it->second.allocation.get())
+      continue;
+    if (it->second.locked)
       continue;
 
     size_t bytes = it->second.bytes;
     DCHECK_LE(bytes, bytes_allocated_);
     bytes_allocated_ -= bytes;
-    free(it->second.memory);
-    it->second.memory = NULL;
+    it->second.allocation.reset();
   }
 }