HostRecordQueue.h - mozsearch

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/* vim:set ts=4 sw=2 sts=2 et cin: */

/* 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 HostRecordQueue_h__

#define HostRecordQueue_h__

#include <functional>

#include "mozilla/Mutex.h"

#include "nsHostRecord.h"

#include "nsRefPtrHashtable.h"

namespace mozilla {

namespace net {

class HostRecordQueue final {

 public:

  HostRecordQueue() = default;

  ~HostRecordQueue() = default;

  HostRecordQueue(const HostRecordQueue& aCopy) = delete;

  HostRecordQueue& operator=(const HostRecordQueue& aCopy) = delete;

  uint32_t PendingCount() const { return mPendingCount; }

  uint32_t EvictionQSize() const { return mEvictionQSize; }

  // Insert the record to mHighQ or mMediumQ or mLowQ based on the record's

  // priority.

  void InsertRecord(nsHostRecord* aRec, nsIDNSService::DNSFlags aFlags,

                    const MutexAutoLock& aProofOfLock);

  // Insert the record to mEvictionQ. In theory, this function should be called

  // when the record is not in any queue.

  void AddToEvictionQ(

      nsHostRecord* aRec, uint32_t aMaxCacheEntries,

      nsRefPtrHashtable<nsGenericHashKey<nsHostKey>, nsHostRecord>& aDB,

      const MutexAutoLock& aProofOfLock);

  // Called for removing the record from mEvictionQ. When this function is

  // called, the record should be either in mEvictionQ or not in any queue.

  void MaybeRenewHostRecord(nsHostRecord* aRec,

                            const MutexAutoLock& aProofOfLock);

  // Called for clearing mEvictionQ.

  void FlushEvictionQ(

      nsRefPtrHashtable<nsGenericHashKey<nsHostKey>, nsHostRecord>& aDB,

      const MutexAutoLock& aProofOfLock);

  // Remove the record from the queue that contains it.

  void MaybeRemoveFromQ(nsHostRecord* aRec, const MutexAutoLock& aProofOfLock);

  // When the record's priority changes, move the record between pending queues.

  void MoveToAnotherPendingQ(nsHostRecord* aRec, nsIDNSService::DNSFlags aFlags,

                             const MutexAutoLock& aProofOfLock);

  // Returning the first record from one of the pending queue. When |aHighQOnly|

  // is true, returning the record from mHighQ only. When false, return the

  // record from mMediumQ or mLowQ.

  already_AddRefed<nsHostRecord> Dequeue(bool aHighQOnly,

                                         const MutexAutoLock& aProofOfLock);

  // Clear all queues and is called only during shutdown. |aCallback| is invoked

  // when a record is removed from a queue.

  void ClearAll(const std::function<void(nsHostRecord*)>& aCallback,

                const MutexAutoLock& aProofOfLock);

 private:

  Atomic<uint32_t> mPendingCount{0};

  Atomic<uint32_t> mEvictionQSize{0};

  LinkedList<RefPtr<nsHostRecord>> mHighQ;

  LinkedList<RefPtr<nsHostRecord>> mMediumQ;

  LinkedList<RefPtr<nsHostRecord>> mLowQ;

  LinkedList<RefPtr<nsHostRecord>> mEvictionQ;

};

}  // namespace net

}  // namespace mozilla

#endif  // HostRecordQueue_h__