storage/browser/file_system/quota/quota_reservation_manager.h

// Copyright 2013 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_FILE_SYSTEM_QUOTA_QUOTA_RESERVATION_MANAGER_H_
#define STORAGE_BROWSER_FILE_SYSTEM_QUOTA_QUOTA_RESERVATION_MANAGER_H_

#include <stdint.h>

#include <map>
#include <memory>
#include <utility>

#include "base/callback_forward.h"
#include "base/component_export.h"
#include "base/files/file.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "storage/common/file_system/file_system_types.h"

namespace url {
class Origin;
}

namespace storage {

class QuotaReservation;
class QuotaReservationBuffer;

class COMPONENT_EXPORT(STORAGE_BROWSER) QuotaReservationManager {
 public:
  // Callback for ReserveQuota. When this callback returns false, ReserveQuota
  // operation should be reverted.
  using ReserveQuotaCallback =
      base::OnceCallback<bool(base::File::Error error, int64_t delta)>;

  // An abstraction of backing quota system.
  class COMPONENT_EXPORT(STORAGE_BROWSER) QuotaBackend {
   public:
    QuotaBackend() = default;

    QuotaBackend(const QuotaBackend&) = delete;
    QuotaBackend& operator=(const QuotaBackend&) = delete;

    virtual ~QuotaBackend() = default;

    // Reserves or reclaims |delta| of quota for |origin| and |type| pair.
    // Reserved quota should be counted as usage, but it should be on-memory
    // and be cleared by a browser restart.
    // Invokes |callback| upon completion with an error code.
    // |callback| should return false if it can't accept the reservation, in
    // that case, the backend should roll back the reservation.
    virtual void ReserveQuota(const url::Origin& origin,
                              FileSystemType type,
                              int64_t delta,
                              ReserveQuotaCallback callback) = 0;

    // Reclaims |size| of quota for |origin| and |type|.
    virtual void ReleaseReservedQuota(const url::Origin& origin,
                                      FileSystemType type,
                                      int64_t size) = 0;

    // Updates disk usage of |origin| and |type|.
    // Invokes |callback| upon completion with an error code.
    virtual void CommitQuotaUsage(const url::Origin& origin,
                                  FileSystemType type,
                                  int64_t delta) = 0;

    virtual void IncrementDirtyCount(const url::Origin& origin,
                                     FileSystemType type) = 0;
    virtual void DecrementDirtyCount(const url::Origin& origin,
                                     FileSystemType type) = 0;
  };

  explicit QuotaReservationManager(std::unique_ptr<QuotaBackend> backend);

  QuotaReservationManager(const QuotaReservationManager&) = delete;
  QuotaReservationManager& operator=(const QuotaReservationManager&) = delete;

  ~QuotaReservationManager();

  // The entry point of the quota reservation.  Creates new reservation object
  // for |origin| and |type|.
  scoped_refptr<QuotaReservation> CreateReservation(const url::Origin& origin,
                                                    FileSystemType type);

 private:
  using ReservationBufferByOriginAndType =
      std::map<std::pair<url::Origin, FileSystemType>, QuotaReservationBuffer*>;

  friend class QuotaReservation;
  friend class QuotaReservationBuffer;
  friend class QuotaReservationManagerTest;

  void ReserveQuota(const url::Origin& origin,
                    FileSystemType type,
                    int64_t delta,
                    ReserveQuotaCallback callback);

  void ReleaseReservedQuota(const url::Origin& origin,
                            FileSystemType type,
                            int64_t size);

  void CommitQuotaUsage(const url::Origin& origin,
                        FileSystemType type,
                        int64_t delta);

  void IncrementDirtyCount(const url::Origin& origin, FileSystemType type);
  void DecrementDirtyCount(const url::Origin& origin, FileSystemType type);

  scoped_refptr<QuotaReservationBuffer> GetReservationBuffer(
      const url::Origin& origin,
      FileSystemType type);
  void ReleaseReservationBuffer(QuotaReservationBuffer* reservation_pool);

  std::unique_ptr<QuotaBackend> backend_;

  // Not owned.  The destructor of ReservationBuffer should erase itself from
  // |reservation_buffers_| by calling ReleaseReservationBuffer.
  ReservationBufferByOriginAndType reservation_buffers_;

  SEQUENCE_CHECKER(sequence_checker_);
  base::WeakPtrFactory<QuotaReservationManager> weak_ptr_factory_{this};
};

}  // namespace storage

#endif  // STORAGE_BROWSER_FILE_SYSTEM_QUOTA_QUOTA_RESERVATION_MANAGER_H_