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       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : #ifndef nsSHistory_h
       8             : #define nsSHistory_h
       9             : 
      10             : #include "nsCOMPtr.h"
      11             : #include "nsExpirationTracker.h"
      12             : #include "nsIPartialSHistoryListener.h"
      13             : #include "nsISHistory.h"
      14             : #include "nsISHistoryInternal.h"
      15             : #include "nsISimpleEnumerator.h"
      16             : #include "nsIWebNavigation.h"
      17             : #include "nsSHEntryShared.h"
      18             : #include "nsTObserverArray.h"
      19             : #include "nsWeakReference.h"
      20             : 
      21             : #include "mozilla/LinkedList.h"
      22             : #include "mozilla/UniquePtr.h"
      23             : 
      24             : class nsIDocShell;
      25             : class nsSHEnumerator;
      26             : class nsSHistoryObserver;
      27             : class nsISHEntry;
      28             : class nsISHTransaction;
      29             : 
      30             : class nsSHistory final : public mozilla::LinkedListElement<nsSHistory>,
      31             :                          public nsISHistory,
      32             :                          public nsISHistoryInternal,
      33             :                          public nsIWebNavigation,
      34             :                          public nsSupportsWeakReference
      35             : {
      36             : public:
      37             : 
      38             :   // The timer based history tracker is used to evict bfcache on expiration.
      39           0 :   class HistoryTracker final : public nsExpirationTracker<nsSHEntryShared, 3>
      40             :   {
      41             :   public:
      42           2 :     explicit HistoryTracker(nsSHistory* aSHistory,
      43             :                             uint32_t aTimeout,
      44             :                             nsIEventTarget* aEventTarget)
      45           2 :       : nsExpirationTracker(1000 * aTimeout / 2, "HistoryTracker", aEventTarget)
      46             :     {
      47           2 :       MOZ_ASSERT(aSHistory);
      48           2 :       mSHistory = aSHistory;
      49           2 :     }
      50             : 
      51             :   protected:
      52           0 :     virtual void NotifyExpired(nsSHEntryShared* aObj)
      53             :     {
      54           0 :       RemoveObject(aObj);
      55           0 :       mSHistory->EvictExpiredContentViewerForEntry(aObj);
      56           0 :     }
      57             : 
      58             :   private:
      59             :     // HistoryTracker is owned by nsSHistory; it always outlives HistoryTracker
      60             :     // so it's safe to use raw pointer here.
      61             :     nsSHistory* mSHistory;
      62             :   };
      63             : 
      64             :   nsSHistory();
      65             :   NS_DECL_ISUPPORTS
      66             :   NS_DECL_NSISHISTORY
      67             :   NS_DECL_NSISHISTORYINTERNAL
      68             :   NS_DECL_NSIWEBNAVIGATION
      69             : 
      70             :   // One time initialization method called upon docshell module construction
      71             :   static nsresult Startup();
      72             :   static void Shutdown();
      73             :   static void UpdatePrefs();
      74             : 
      75             :   // Max number of total cached content viewers.  If the pref
      76             :   // browser.sessionhistory.max_total_viewers is negative, then
      77             :   // this value is calculated based on the total amount of memory.
      78             :   // Otherwise, it comes straight from the pref.
      79           0 :   static uint32_t GetMaxTotalViewers() { return sHistoryMaxTotalViewers; }
      80             : 
      81             : private:
      82             :   virtual ~nsSHistory();
      83             :   friend class nsSHEnumerator;
      84             :   friend class nsSHistoryObserver;
      85             : 
      86             :   // Could become part of nsIWebNavigation
      87             :   NS_IMETHOD GetTransactionAtIndex(int32_t aIndex, nsISHTransaction** aResult);
      88             :   nsresult LoadDifferingEntries(nsISHEntry* aPrevEntry, nsISHEntry* aNextEntry,
      89             :                                 nsIDocShell* aRootDocShell, long aLoadType,
      90             :                                 bool& aDifferenceFound);
      91             :   nsresult InitiateLoad(nsISHEntry* aFrameEntry, nsIDocShell* aFrameDS,
      92             :                         long aLoadType);
      93             : 
      94             :   NS_IMETHOD LoadEntry(int32_t aIndex, long aLoadType, uint32_t aHistCmd);
      95             : 
      96             : #ifdef DEBUG
      97             :   nsresult PrintHistory();
      98             : #endif
      99             : 
     100             :   // Evict content viewers in this window which don't lie in the "safe" range
     101             :   // around aIndex.
     102             :   void EvictOutOfRangeWindowContentViewers(int32_t aIndex);
     103             :   void EvictContentViewerForTransaction(nsISHTransaction* aTrans);
     104             :   static void GloballyEvictContentViewers();
     105             :   static void GloballyEvictAllContentViewers();
     106             : 
     107             :   // Calculates a max number of total
     108             :   // content viewers to cache, based on amount of total memory
     109             :   static uint32_t CalcMaxTotalViewers();
     110             : 
     111             :   nsresult LoadNextPossibleEntry(int32_t aNewIndex, long aLoadType,
     112             :                                  uint32_t aHistCmd);
     113             : 
     114             :   // aIndex is the index of the transaction which may be removed.
     115             :   // If aKeepNext is true, aIndex is compared to aIndex + 1,
     116             :   // otherwise comparison is done to aIndex - 1.
     117             :   bool RemoveDuplicate(int32_t aIndex, bool aKeepNext);
     118             : 
     119             :   // Track all bfcache entries and evict on expiration.
     120             :   mozilla::UniquePtr<HistoryTracker> mHistoryTracker;
     121             : 
     122             :   nsCOMPtr<nsISHTransaction> mListRoot;
     123             :   int32_t mIndex;
     124             :   int32_t mLength;
     125             :   int32_t mRequestedIndex;
     126             : 
     127             :   // The number of entries before this session history object.
     128             :   int32_t mGlobalIndexOffset;
     129             : 
     130             :   // The number of entries after this session history object.
     131             :   int32_t mEntriesInFollowingPartialHistories;
     132             : 
     133             :   // Session History listeners
     134             :   nsAutoTObserverArray<nsWeakPtr, 2> mListeners;
     135             : 
     136             :   // Partial session history listener
     137             :   nsWeakPtr mPartialHistoryListener;
     138             : 
     139             :   // Weak reference. Do not refcount this.
     140             :   nsIDocShell* mRootDocShell;
     141             : 
     142             :   // Set to true if attached to a grouped session history.
     143             :   bool mIsPartial;
     144             : 
     145             :   // Max viewers allowed total, across all SHistory objects
     146             :   static int32_t sHistoryMaxTotalViewers;
     147             : };
     148             : 
     149             : class nsSHEnumerator : public nsISimpleEnumerator
     150             : {
     151             : public:
     152             :   NS_DECL_ISUPPORTS
     153             :   NS_DECL_NSISIMPLEENUMERATOR
     154             : 
     155             :   explicit nsSHEnumerator(nsSHistory* aHistory);
     156             : 
     157             : protected:
     158             :   friend class nsSHistory;
     159             :   virtual ~nsSHEnumerator();
     160             : 
     161             : private:
     162             :   int32_t mIndex;
     163             :   nsSHistory* mSHistory;
     164             : };
     165             : 
     166             : #endif /* nsSHistory */