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// Copyright 2017 The Chromium Authors
// 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 <ostream>
#include <utility>
#include "base/check_op.h"
#include "base/sequence_token.h"
#include "third_party/abseil-cpp/absl/base/attributes.h"
namespace base {
namespace internal {
namespace {
ABSL_CONST_INIT thread_local SequenceLocalStorageMap*
current_sequence_local_storage = nullptr;
} // namespace
SequenceLocalStorageMap::SequenceLocalStorageMap() = default;
SequenceLocalStorageMap::~SequenceLocalStorageMap() = default;
// static
SequenceLocalStorageMap& SequenceLocalStorageMap::GetForCurrentThread() {
CHECK(!CurrentTaskIsRunningSynchronously());
DCHECK(IsSetForCurrentThread())
<< "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;
}
// static
bool SequenceLocalStorageMap::IsSetForCurrentThread() {
return current_sequence_local_storage != nullptr;
}
bool SequenceLocalStorageMap::Has(int slot_id) const {
return const_cast<SequenceLocalStorageMap*>(this)->Get(slot_id) != nullptr;
}
void SequenceLocalStorageMap::Reset(int slot_id) {
sls_map_.erase(slot_id);
}
SequenceLocalStorageMap::Value* SequenceLocalStorageMap::Get(int slot_id) {
auto it = sls_map_.find(slot_id);
if (it != sls_map_.end()) {
return it->second.get();
}
return nullptr;
}
SequenceLocalStorageMap::Value* SequenceLocalStorageMap::Set(
int slot_id,
SequenceLocalStorageMap::ValueDestructorPair value_destructor_pair) {
auto it = sls_map_.find(slot_id);
if (it == sls_map_.end())
it = sls_map_.emplace(slot_id, std::move(value_destructor_pair)).first;
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);
return it->second.get();
}
SequenceLocalStorageMap::ValueDestructorPair::ValueDestructorPair()
: destructor_(nullptr) {}
SequenceLocalStorageMap::ValueDestructorPair::ValueDestructorPair(
ExternalValue value,
DestructorFunc* destructor)
: value_{.external_value = std::move(value)}, destructor_(destructor) {}
SequenceLocalStorageMap::ValueDestructorPair::ValueDestructorPair(
InlineValue value,
DestructorFunc* destructor)
: value_{.inline_value = std::move(value)}, destructor_(destructor) {}
SequenceLocalStorageMap::ValueDestructorPair::~ValueDestructorPair() {
if (destructor_) {
destructor_(&value_);
}
}
SequenceLocalStorageMap::ValueDestructorPair::ValueDestructorPair(
ValueDestructorPair&& value_destructor_pair)
: value_(value_destructor_pair.value_),
destructor_(value_destructor_pair.destructor_) {
value_destructor_pair.destructor_ = nullptr;
}
SequenceLocalStorageMap::ValueDestructorPair&
SequenceLocalStorageMap::ValueDestructorPair::operator=(
ValueDestructorPair&& value_destructor_pair) {
if (this == &value_destructor_pair) {
return *this;
}
// Destroy |value_| before overwriting it with a new value.
if (destructor_) {
destructor_(&value_);
}
value_ = value_destructor_pair.value_;
destructor_ = std::exchange(value_destructor_pair.destructor_, nullptr);
return *this;
}
SequenceLocalStorageMap::ValueDestructorPair::operator bool() const {
return destructor_ != nullptr;
}
ScopedSetSequenceLocalStorageMapForCurrentThread::
ScopedSetSequenceLocalStorageMapForCurrentThread(
SequenceLocalStorageMap* sequence_local_storage)
: resetter_(¤t_sequence_local_storage,
sequence_local_storage,
nullptr) {}
ScopedSetSequenceLocalStorageMapForCurrentThread::
~ScopedSetSequenceLocalStorageMapForCurrentThread() = default;
} // namespace internal
} // namespace base
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