netwerk/cache/nsDiskCacheBinding.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  *
   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
   8 #ifndef _nsDiskCacheBinding_h_
   9 #define _nsDiskCacheBinding_h_
  10
  11 #include "mozilla/MemoryReporting.h"
  12 #include "nspr.h"
  13 #include "pldhash.h"
  14
  15 #include "nsISupports.h"
  16 #include "nsCacheEntry.h"
  17
  18 #include "nsDiskCacheMap.h"
  19 #include "nsDiskCacheStreams.h"
  20
  21
  22 /******************************************************************************
  23  *  nsDiskCacheBinding
  24  *
  25  *  Created for disk cache specific data and stored in nsCacheEntry.mData as
  26  *  an nsISupports.  Also stored in nsDiskCacheHashTable, with collisions
  27  *  linked by the PRCList.
  28  *
  29  *****************************************************************************/
  30
  31 class nsDiskCacheDeviceDeactivateEntryEvent;
  32
  33 class nsDiskCacheBinding : public nsISupports, public PRCList {
  34     virtual ~nsDiskCacheBinding();
  35
  36 public:
  37     NS_DECL_THREADSAFE_ISUPPORTS
  38
  39     nsDiskCacheBinding(nsCacheEntry* entry, nsDiskCacheRecord * record);
  40
  41     nsresult EnsureStreamIO();
  42     bool     IsActive() { return mCacheEntry != nullptr;}
  43
  44 // XXX make friends
  45 public:
  46     nsCacheEntry*           mCacheEntry;    // back pointer to parent nsCacheEntry
  47     nsDiskCacheRecord       mRecord;
  48     nsDiskCacheStreamIO*    mStreamIO;      // strong reference
  49     bool                    mDoomed;        // record is not stored in cache map
  50     uint8_t                 mGeneration;    // possibly just reservation
  51
  52     // If set, points to a pending event which will deactivate |mCacheEntry|.
  53     // If not set then either |mCacheEntry| is not deactivated, or it has been
  54     // deactivated but the device returned it from FindEntry() before the event
  55     // fired. In both two latter cases this binding is to be considered valid.
  56     nsDiskCacheDeviceDeactivateEntryEvent *mDeactivateEvent;
  57 };
  58
  59
  60 /******************************************************************************
  61  *  Utility Functions
  62  *****************************************************************************/
  63
  64 nsDiskCacheBinding *   GetCacheEntryBinding(nsCacheEntry * entry);
  65
  66
  67
  68 /******************************************************************************
  69  *  nsDiskCacheBindery
  70  *
  71  *  Used to keep track of nsDiskCacheBinding associated with active/bound (and
  72  *  possibly doomed) entries.  Lookups on 4 byte disk hash to find collisions
  73  *  (which need to be doomed, instead of just evicted.  Collisions are linked
  74  *  using a PRCList to keep track of current generation number.
  75  *
  76  *  Used to detect hash number collisions, and find available generation numbers.
  77  *
  78  *  Not all nsDiskCacheBinding have a generation number.
  79  *
  80  *  Generation numbers may be aquired late, or lost (when data fits in block file)
  81  *
  82  *  Collisions can occur:
  83  *      BindEntry()       - hashnumbers collide (possibly different keys)
  84  *
  85  *  Generation number required:
  86  *      DeactivateEntry() - metadata written to disk, may require file
  87  *      GetFileForEntry() - force data to require file
  88  *      writing to stream - data size may require file
  89  *
  90  *  Binding can be kept in PRCList in order of generation numbers.
  91  *  Binding with no generation number can be Appended to PRCList (last).
  92  *
  93  *****************************************************************************/
  94
  95 class nsDiskCacheBindery {
  96 public:
  97     nsDiskCacheBindery();
  98     ~nsDiskCacheBindery();
  99
 100     nsresult                Init();
 101     void                    Reset();
 102
 103     nsDiskCacheBinding *    CreateBinding(nsCacheEntry *       entry,
 104                                           nsDiskCacheRecord *  record);
 105
 106     nsDiskCacheBinding *    FindActiveBinding(uint32_t  hashNumber);
 107     void                    RemoveBinding(nsDiskCacheBinding * binding);
 108     bool                    ActiveBindings();
 109
 110     size_t                 SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf);
 111
 112 private:
 113     nsresult                AddBinding(nsDiskCacheBinding * binding);
 114
 115     // member variables
 116     static const PLDHashTableOps ops;
 117     PLDHashTable           table;
 118     bool                   initialized;
 119 };
 120
 121 #endif /* _nsDiskCacheBinding_h_ */