CookieDBWriteQueue.h

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/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_net_CookieDBWriteQueue_h

#define mozilla_net_CookieDBWriteQueue_h

#include "gtest/MozGtestFriend.h"

#include "mozilla/Maybe.h"

#include "mozilla/RefPtr.h"

#include "nsCOMPtr.h"

#include "nsHashKeys.h"

#include "nsString.h"

#include "nsTArray.h"

#include "nsTHashMap.h"

class nsITimer;

namespace mozilla {

namespace net {

class Cookie;

class CookiePersistentStorage;

// Buffers the changes CookiePersistentStorage wants to persist and writes them

// out in batches.

//

// Changes are coalesced per database row, keyed on the (host, name, path,

// originAttributes) tuple that moz_cookies is UNIQUE on: operations on distinct

// rows commute, and for a given row only the final state matters. Within a

// batch every DELETE is emitted before every INSERT, so an overwrite stays

// ordered.

class CookieDBWriteQueue final {

 public:

  explicit CookieDBWriteQueue(CookiePersistentStorage* aStorage);

  ~CookieDBWriteQueue();

  void Insert(Cookie* aCookie);

  void Update(Cookie* aCookie);

  void Remove(Cookie* aCookie);

  bool IsIdle() const { return mPending.IsEmpty() && mFlushesInFlight == 0; }

  void Clear();

  void FlushNow();

  void OnFlushCompleted();

 private:

  FRIEND_TEST(TestCookieDBWriteQueue, Coalesce);

  enum class OpType : uint8_t {

    Insert,           // the row must exist with these values

    Update,           // the row exists, only lastAccessed changed

    Remove,           // the row must not exist

    RemoveAndInsert,  // overwrite: drop the old row, then insert the new one

};

  struct PendingOp {

    RefPtr<Cookie> mCookie;

    OpType mType;

};

  static void RowKey(const Cookie* aCookie, nsACString& aKey);

  static Maybe<OpType> Coalesce(OpType aPending, OpType aNew);

  void Enqueue(Cookie* aCookie, OpType aOp);

  void MaybeScheduleFlush();

  void CancelTimer();

  void Flush();

  CookiePersistentStorage* MOZ_NON_OWNING_REF mStorage;

  nsTHashMap<nsCStringHashKey, PendingOp> mPending;

  nsCOMPtr<nsITimer> mTimer;

  // Usually at most one: only the timer waits for the batch in flight.

  // FlushNow() dispatches unconditionally, because at shutdown a deferred

  // flush would come after the connection is already closing.

  uint32_t mFlushesInFlight = 0;

};

}  // namespace net

}  // namespace mozilla

#endif  // mozilla_net_CookieDBWriteQueue_h