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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef STORAGE_BROWSER_BLOB_SHAREABLE_FILE_REFERENCE_H_
#define STORAGE_BROWSER_BLOB_SHAREABLE_FILE_REFERENCE_H_
#include "base/component_export.h"
#include "base/memory/ref_counted.h"
#include "storage/browser/blob/scoped_file.h"
namespace storage {
// ShareableFileReference allows consumers to share FileReference for the
// same path if it already exists in its internal map.
// This class is non-thread-safe and all methods must be called on a single
// thread.
class COMPONENT_EXPORT(STORAGE_BROWSER) ShareableFileReference
: public base::RefCounted<ShareableFileReference> {
public:
using FinalReleaseCallback = ScopedFile::ScopeOutCallback;
enum FinalReleasePolicy {
DELETE_ON_FINAL_RELEASE = ScopedFile::DELETE_ON_SCOPE_OUT,
DONT_DELETE_ON_FINAL_RELEASE = ScopedFile::DONT_DELETE_ON_SCOPE_OUT,
};
// Returns a ShareableFileReference for the given path, if no reference
// for this path exists returns nullptr.
static scoped_refptr<ShareableFileReference> Get(const base::FilePath& path);
// Returns a ShareableFileReference for the given path, creating a new
// reference if none yet exists. If there's a pre-existing reference for
// the path, the policy parameter of this method is ignored.
static scoped_refptr<ShareableFileReference> GetOrCreate(
const base::FilePath& path,
FinalReleasePolicy policy,
base::TaskRunner* file_task_runner);
// Returns a ShareableFileReference for the given path of the |scoped_file|,
// creating a new reference if none yet exists. The ownership of |scoped_file|
// is passed to this reference.
// If there's a pre-existing reference for the path, the scope out policy
// and scope-out-callbacks of the given |scoped_file| is ignored.
// If the given scoped_file has an empty path (e.g. maybe already
// released) this returns nullptr reference.
//
// TODO(kinuko): Make sure if this behavior is ok, we could alternatively
// merge callbacks to the existing one.
static scoped_refptr<ShareableFileReference> GetOrCreate(
ScopedFile scoped_file);
ShareableFileReference(const ShareableFileReference&) = delete;
ShareableFileReference& operator=(const ShareableFileReference&) = delete;
// The full file path.
const base::FilePath& path() const { return scoped_file_.path(); }
// The |callback| is fired when the final reference of this instance
// is released. If release policy is DELETE_ON_FINAL_RELEASE the
// callback task(s) is/are posted before the deletion is scheduled.
// The callbacks are posted in reverse of the order they were added, because
// LIFO order makes it possible for later cleanup callbacks to restore state
// earlier added callbacks might rely on (this is relied on by for example
// code in BlobMemoryController, when shrinking file allocations).
void AddFinalReleaseCallback(FinalReleaseCallback callback);
private:
friend class base::RefCounted<ShareableFileReference>;
ShareableFileReference(ScopedFile scoped_file);
~ShareableFileReference();
ScopedFile scoped_file_;
};
} // namespace storage
#endif // STORAGE_BROWSER_BLOB_SHAREABLE_FILE_REFERENCE_H_
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