blob: 83e4ebc20c997c204581e3f0e3089779b34d7d55 [file] [log] [blame]
// Copyright 2017 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/threading/sequence_local_storage_map.h"
#include <utility>
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/threading/thread_local.h"
namespace base {
namespace internal {
namespace {
LazyInstance<ThreadLocalPointer<SequenceLocalStorageMap>>::Leaky
tls_current_sequence_local_storage = LAZY_INSTANCE_INITIALIZER;
} // namespace
SequenceLocalStorageMap::SequenceLocalStorageMap() = default;
SequenceLocalStorageMap::~SequenceLocalStorageMap() = default;
ScopedSetSequenceLocalStorageMapForCurrentThread::
ScopedSetSequenceLocalStorageMapForCurrentThread(
SequenceLocalStorageMap* sequence_local_storage)
: old_sequence_local_storage_(
tls_current_sequence_local_storage.Get().Get()) {
// TODO(jeffreyhe): Add check to make sure no
// ScopedSetSequenceLocalStorageMapForCurrentThread is already instantiated
// (DCHECK(!tls_current_sequence_local_storage.Get().Get()))
// once ScopedTaskScheduler is removed.
tls_current_sequence_local_storage.Get().Set(sequence_local_storage);
}
ScopedSetSequenceLocalStorageMapForCurrentThread::
~ScopedSetSequenceLocalStorageMapForCurrentThread() {
// Restore the previous value in |tls_current_sequence_local_storage|.
tls_current_sequence_local_storage.Get().Set(old_sequence_local_storage_);
}
SequenceLocalStorageMap& SequenceLocalStorageMap::GetForCurrentThread() {
SequenceLocalStorageMap* current_sequence_local_storage =
tls_current_sequence_local_storage.Get().Get();
DCHECK(current_sequence_local_storage)
<< "SequenceLocalStorageSlot cannot be used because no "
"SequenceLocalStorageMap was stored in TLS. Use "
"ScopedSetSequenceLocalStorageMapForCurrentThread to store a "
"SequenceLocalStorageMap object in TLS.";
return *current_sequence_local_storage;
}
void* SequenceLocalStorageMap::Get(int slot_id) {
const auto it = sls_map_.find(slot_id);
if (it == sls_map_.end())
return nullptr;
return it->second.value();
}
void SequenceLocalStorageMap::Set(
int slot_id,
SequenceLocalStorageMap::ValueDestructorPair value_destructor_pair) {
auto it = sls_map_.find(slot_id);
if (it == sls_map_.end())
sls_map_.emplace(slot_id, std::move(value_destructor_pair));
else
it->second = std::move(value_destructor_pair);
// The maximum number of entries in the map is 256. This can be adjusted, but
// will require reviewing the choice of data structure for the map.
DCHECK_LE(sls_map_.size(), 256U);
}
SequenceLocalStorageMap::ValueDestructorPair::ValueDestructorPair(
void* value,
DestructorFunc* destructor)
: value_(value), destructor_(destructor) {}
SequenceLocalStorageMap::ValueDestructorPair::~ValueDestructorPair() {
if (value_)
destructor_(value_);
}
SequenceLocalStorageMap::ValueDestructorPair::ValueDestructorPair(
ValueDestructorPair&& value_destructor_pair)
: value_(value_destructor_pair.value_),
destructor_(value_destructor_pair.destructor_) {
value_destructor_pair.value_ = nullptr;
}
SequenceLocalStorageMap::ValueDestructorPair&
SequenceLocalStorageMap::ValueDestructorPair::operator=(
ValueDestructorPair&& value_destructor_pair) {
// Destroy |value_| before overwriting it with a new value.
if (value_)
destructor_(value_);
value_ = value_destructor_pair.value_;
destructor_ = value_destructor_pair.destructor_;
value_destructor_pair.value_ = nullptr;
return *this;
}
} // namespace internal
} // namespace base