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- // Copyright (c) 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.
- // Internal helper used to sequence cleanup and reuse of cache directories
- // among different objects.
- #include "net/disk_cache/backend_cleanup_tracker.h"
- #include <unordered_map>
- #include <utility>
- #include "base/callback.h"
- #include "base/files/file_path.h"
- #include "base/lazy_instance.h"
- #include "base/memory/ref_counted.h"
- #include "base/synchronization/lock.h"
- #include "base/task/sequenced_task_runner.h"
- #include "base/threading/sequenced_task_runner_handle.h"
- namespace disk_cache {
- namespace {
- using TrackerMap = std::unordered_map<base::FilePath, BackendCleanupTracker*>;
- struct AllBackendCleanupTrackers {
- TrackerMap map;
- // Since clients can potentially call CreateCacheBackend from multiple
- // threads, we need to lock the map keeping track of cleanup trackers
- // for these backends. Our overall strategy is to have TryCreate
- // acts as an arbitrator --- whatever thread grabs one, gets to operate
- // on the tracker freely until it gets destroyed.
- base::Lock lock;
- };
- static base::LazyInstance<AllBackendCleanupTrackers>::Leaky g_all_trackers;
- } // namespace.
- // static
- scoped_refptr<BackendCleanupTracker> BackendCleanupTracker::TryCreate(
- const base::FilePath& path,
- base::OnceClosure retry_closure) {
- AllBackendCleanupTrackers* all_trackers = g_all_trackers.Pointer();
- base::AutoLock lock(all_trackers->lock);
- std::pair<TrackerMap::iterator, bool> insert_result =
- all_trackers->map.insert(
- std::pair<base::FilePath, BackendCleanupTracker*>(path, nullptr));
- if (insert_result.second) {
- auto tracker = base::WrapRefCounted(new BackendCleanupTracker(path));
- insert_result.first->second = tracker.get();
- return tracker;
- } else {
- insert_result.first->second->AddPostCleanupCallbackImpl(
- std::move(retry_closure));
- return nullptr;
- }
- }
- void BackendCleanupTracker::AddPostCleanupCallback(base::OnceClosure cb) {
- DCHECK_CALLED_ON_VALID_SEQUENCE(seq_checker_);
- // Despite the sequencing requirement we need to grab the table lock since
- // this may otherwise race against TryMakeContext.
- base::AutoLock lock(g_all_trackers.Get().lock);
- AddPostCleanupCallbackImpl(std::move(cb));
- }
- void BackendCleanupTracker::AddPostCleanupCallbackImpl(base::OnceClosure cb) {
- post_cleanup_cbs_.emplace_back(base::SequencedTaskRunnerHandle::Get(),
- std::move(cb));
- }
- BackendCleanupTracker::BackendCleanupTracker(const base::FilePath& path)
- : path_(path) {}
- BackendCleanupTracker::~BackendCleanupTracker() {
- DCHECK_CALLED_ON_VALID_SEQUENCE(seq_checker_);
- {
- AllBackendCleanupTrackers* all_trackers = g_all_trackers.Pointer();
- base::AutoLock lock(all_trackers->lock);
- int rv = all_trackers->map.erase(path_);
- DCHECK_EQ(1, rv);
- }
- while (!post_cleanup_cbs_.empty()) {
- post_cleanup_cbs_.back().first->PostTask(
- FROM_HERE, std::move(post_cleanup_cbs_.back().second));
- post_cleanup_cbs_.pop_back();
- }
- }
- } // namespace disk_cache
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