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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.
#ifndef NET_DISK_CACHE_BACKEND_CLEANUP_TRACKER_H_
#define NET_DISK_CACHE_BACKEND_CLEANUP_TRACKER_H_
#include <utility>
#include <vector>
#include "base/files/file_path.h"
#include "base/functional/callback.h"
#include "base/memory/ref_counted.h"
#include "base/sequence_checker.h"
#include "net/base/net_export.h"
namespace base {
class SequencedTaskRunner;
} // namespace base
namespace disk_cache {
// Internal helper used to sequence cleanup and reuse of cache directories.
// One of these is created before each backend, and is kept alive till both
// the backend is destroyed and all of its work is done by its refcount,
// which keeps track of outstanding work. That refcount is expected to only be
// updated from the I/O thread or its equivalent.
class NET_EXPORT_PRIVATE BackendCleanupTracker
: public base::RefCounted<BackendCleanupTracker> {
public:
// Either returns a fresh cleanup tracker for |path| if none exists, or
// will eventually post |retry_closure| to the calling thread,
// and return null.
static scoped_refptr<BackendCleanupTracker> TryCreate(
const base::FilePath& path,
base::OnceClosure retry_closure);
BackendCleanupTracker(const BackendCleanupTracker&) = delete;
BackendCleanupTracker& operator=(const BackendCleanupTracker&) = delete;
// Register a callback to be posted after all the work of associated
// context is complete (which will result in destruction of this context).
// Should only be called by owner, on its I/O-thread-like execution context,
// and will in turn eventually post |cb| there.
void AddPostCleanupCallback(base::OnceClosure cb);
private:
friend class base::RefCounted<BackendCleanupTracker>;
explicit BackendCleanupTracker(const base::FilePath& path);
~BackendCleanupTracker();
void AddPostCleanupCallbackImpl(base::OnceClosure cb);
base::FilePath path_;
// Since it's possible that a different thread may want to create a
// cache for a reused path, we keep track of runners contexts of
// post-cleanup callbacks.
std::vector<
std::pair<scoped_refptr<base::SequencedTaskRunner>, base::OnceClosure>>
post_cleanup_cbs_;
// We expect only TryMakeContext to be multithreaded, everything
// else should be sequenced.
SEQUENCE_CHECKER(seq_checker_);
};
} // namespace disk_cache
#endif // NET_DISK_CACHE_BACKEND_CLEANUP_TRACKER_H_
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