netwerk/dns/HostRecordQueue.h

   1 /* vim:set ts=4 sw=2 sts=2 et cin: */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef HostRecordQueue_h__
   7 #define HostRecordQueue_h__
   8
   9 #include <functional>
  10 #include "mozilla/Mutex.h"
  11 #include "nsHostRecord.h"
  12 #include "nsRefPtrHashtable.h"
  13
  14 namespace mozilla {
  15 namespace net {
  16
  17 class HostRecordQueue final {
  18  public:
  19   HostRecordQueue() = default;
  20   ~HostRecordQueue() = default;
  21   HostRecordQueue(const HostRecordQueue& aCopy) = delete;
  22   HostRecordQueue& operator=(const HostRecordQueue& aCopy) = delete;
  23
  24   uint32_t PendingCount() const { return mPendingCount; }
  25   uint32_t EvictionQSize() const { return mEvictionQSize; }
  26
  27   // Insert the record to mHighQ or mMediumQ or mLowQ based on the record's
  28   // priority.
  29   void InsertRecord(nsHostRecord* aRec, nsIDNSService::DNSFlags aFlags,
  30                     const MutexAutoLock& aProofOfLock);
  31   // Insert the record to mEvictionQ. In theory, this function should be called
  32   // when the record is not in any queue.
  33   void AddToEvictionQ(
  34       nsHostRecord* aRec, uint32_t aMaxCacheEntries,
  35       nsRefPtrHashtable<nsGenericHashKey<nsHostKey>, nsHostRecord>& aDB,
  36       const MutexAutoLock& aProofOfLock);
  37   // Called for removing the record from mEvictionQ. When this function is
  38   // called, the record should be either in mEvictionQ or not in any queue.
  39   void MaybeRenewHostRecord(nsHostRecord* aRec,
  40                             const MutexAutoLock& aProofOfLock);
  41   // Called for clearing mEvictionQ.
  42   void FlushEvictionQ(
  43       nsRefPtrHashtable<nsGenericHashKey<nsHostKey>, nsHostRecord>& aDB,
  44       const MutexAutoLock& aProofOfLock);
  45   // Remove the record from the queue that contains it.
  46   void MaybeRemoveFromQ(nsHostRecord* aRec, const MutexAutoLock& aProofOfLock);
  47   // When the record's priority changes, move the record between pending queues.
  48   void MoveToAnotherPendingQ(nsHostRecord* aRec, nsIDNSService::DNSFlags aFlags,
  49                              const MutexAutoLock& aProofOfLock);
  50   // Returning the first record from one of the pending queue. When |aHighQOnly|
  51   // is true, returning the record from mHighQ only. When false, return the
  52   // record from mMediumQ or mLowQ.
  53   already_AddRefed<nsHostRecord> Dequeue(bool aHighQOnly,
  54                                          const MutexAutoLock& aProofOfLock);
  55   // Clear all queues and is called only during shutdown. |aCallback| is invoked
  56   // when a record is removed from a queue.
  57   void ClearAll(const std::function<void(nsHostRecord*)>& aCallback,
  58                 const MutexAutoLock& aProofOfLock);
  59
  60  private:
  61   Atomic<uint32_t> mPendingCount{0};
  62   Atomic<uint32_t> mEvictionQSize{0};
  63   LinkedList<RefPtr<nsHostRecord>> mHighQ;
  64   LinkedList<RefPtr<nsHostRecord>> mMediumQ;
  65   LinkedList<RefPtr<nsHostRecord>> mLowQ;
  66   LinkedList<RefPtr<nsHostRecord>> mEvictionQ;
  67 };
  68
  69 }  // namespace net
  70 }  // namespace mozilla
  71
  72 #endif  // HostRecordQueue_h__