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- // Copyright 2021 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/unsafe_shared_memory_pool.h"
- #include "base/logging.h"
- namespace {
- constexpr size_t kMaxStoredBuffers = 32;
- } // namespace
- namespace base {
- UnsafeSharedMemoryPool::UnsafeSharedMemoryPool() = default;
- UnsafeSharedMemoryPool::~UnsafeSharedMemoryPool() = default;
- UnsafeSharedMemoryPool::Handle::Handle(
- PassKey<UnsafeSharedMemoryPool>,
- UnsafeSharedMemoryRegion region,
- WritableSharedMemoryMapping mapping,
- scoped_refptr<UnsafeSharedMemoryPool> pool)
- : region_(std::move(region)),
- mapping_(std::move(mapping)),
- pool_(std::move(pool)) {
- CHECK(pool_);
- DCHECK(region_.IsValid());
- DCHECK(mapping_.IsValid());
- }
- UnsafeSharedMemoryPool::Handle::~Handle() {
- pool_->ReleaseBuffer(std::move(region_), std::move(mapping_));
- }
- const UnsafeSharedMemoryRegion& UnsafeSharedMemoryPool::Handle::GetRegion()
- const {
- return region_;
- }
- const WritableSharedMemoryMapping& UnsafeSharedMemoryPool::Handle::GetMapping()
- const {
- return mapping_;
- }
- std::unique_ptr<UnsafeSharedMemoryPool::Handle>
- UnsafeSharedMemoryPool::MaybeAllocateBuffer(size_t region_size) {
- AutoLock lock(lock_);
- DCHECK_GE(region_size, 0u);
- if (is_shutdown_)
- return nullptr;
- // Only change the configured size if bigger region is requested to avoid
- // unncecessary reallocations.
- if (region_size > region_size_) {
- regions_.clear();
- region_size_ = region_size;
- }
- if (!regions_.empty()) {
- auto region = std::move(regions_.back());
- regions_.pop_back();
- DCHECK_GE(region.first.GetSize(), region_size_);
- auto handle = std::make_unique<Handle>(PassKey<UnsafeSharedMemoryPool>(),
- std::move(region.first),
- std::move(region.second), this);
- return handle;
- }
- auto region = UnsafeSharedMemoryRegion::Create(region_size_);
- if (!region.IsValid())
- return nullptr;
- WritableSharedMemoryMapping mapping = region.Map();
- if (!mapping.IsValid())
- return nullptr;
- return std::make_unique<Handle>(PassKey<UnsafeSharedMemoryPool>(),
- std::move(region), std::move(mapping), this);
- }
- void UnsafeSharedMemoryPool::Shutdown() {
- AutoLock lock(lock_);
- DCHECK(!is_shutdown_);
- is_shutdown_ = true;
- regions_.clear();
- }
- void UnsafeSharedMemoryPool::ReleaseBuffer(
- UnsafeSharedMemoryRegion region,
- WritableSharedMemoryMapping mapping) {
- AutoLock lock(lock_);
- // Only return regions which are at least as big as the current configuration.
- if (is_shutdown_ || regions_.size() >= kMaxStoredBuffers ||
- !region.IsValid() || region.GetSize() < region_size_) {
- DLOG(WARNING) << "Not returning SharedMemoryRegion to the pool:"
- << " is_shutdown: " << (is_shutdown_ ? "true" : "false")
- << " stored regions: " << regions_.size()
- << " configured size: " << region_size_
- << " this region size: " << region.GetSize()
- << " valid: " << (region.IsValid() ? "true" : "false");
- return;
- }
- regions_.emplace_back(std::move(region), std::move(mapping));
- }
- } // namespace base
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