netwerk/cache/src/nsDiskCacheBinding.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  *
   3  * ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is nsDiskCacheBinding.h, released
  17  * May 10, 2001.
  18  *
  19  * The Initial Developer of the Original Code is
  20  * Netscape Communications Corporation.
  21  * Portions created by the Initial Developer are Copyright (C) 2001
  22  * the Initial Developer. All Rights Reserved.
  23  *
  24  * Contributor(s):
  25  *   Gordon Sheridan  <gordon@netscape.com>
  26  *   Patrick C. Beard <beard@netscape.com>
  27  *
  28  * Alternatively, the contents of this file may be used under the terms of
  29  * either the GNU General Public License Version 2 or later (the "GPL"), or
  30  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  31  * in which case the provisions of the GPL or the LGPL are applicable instead
  32  * of those above. If you wish to allow use of your version of this file only
  33  * under the terms of either the GPL or the LGPL, and not to allow others to
  34  * use your version of this file under the terms of the MPL, indicate your
  35  * decision by deleting the provisions above and replace them with the notice
  36  * and other provisions required by the GPL or the LGPL. If you do not delete
  37  * the provisions above, a recipient may use your version of this file under
  38  * the terms of any one of the MPL, the GPL or the LGPL.
  39  *
  40  * ***** END LICENSE BLOCK ***** */
  41
  42
  43 #ifndef _nsDiskCacheBinding_h_
  44 #define _nsDiskCacheBinding_h_
  45
  46 #include "nspr.h"
  47 #include "pldhash.h"
  48
  49 #include "nsISupports.h"
  50 #include "nsCacheEntry.h"
  51
  52 #include "nsDiskCacheMap.h"
  53 #include "nsDiskCacheStreams.h"
  54
  55
  56 /******************************************************************************
  57  *  nsDiskCacheBinding
  58  *
  59  *  Created for disk cache specific data and stored in nsCacheEntry.mData as
  60  *  an nsISupports.  Also stored in nsDiskCacheHashTable, with collisions
  61  *  linked by the PRCList.
  62  *
  63  *****************************************************************************/
  64
  65 class nsDiskCacheBinding : public nsISupports, public PRCList {
  66 public:
  67     NS_DECL_ISUPPORTS
  68
  69     nsDiskCacheBinding(nsCacheEntry* entry, nsDiskCacheRecord * record);
  70     virtual ~nsDiskCacheBinding();
  71
  72     nsresult EnsureStreamIO();
  73     PRBool   IsActive() { return mCacheEntry != nsnull;}
  74
  75 // XXX make friends
  76 public:
  77     nsCacheEntry*           mCacheEntry;    // back pointer to parent nsCacheEntry
  78     nsDiskCacheRecord       mRecord;
  79     nsDiskCacheStreamIO*    mStreamIO;      // strong reference
  80     PRBool                  mDoomed;        // record is not stored in cache map
  81     PRUint8                 mGeneration;    // possibly just reservation
  82 };
  83
  84
  85 /******************************************************************************
  86  *  Utility Functions
  87  *****************************************************************************/
  88
  89 nsDiskCacheBinding *   GetCacheEntryBinding(nsCacheEntry * entry);
  90
  91
  92
  93 /******************************************************************************
  94  *  nsDiskCacheBindery
  95  *
  96  *  Used to keep track of nsDiskCacheBinding associated with active/bound (and
  97  *  possibly doomed) entries.  Lookups on 4 byte disk hash to find collisions
  98  *  (which need to be doomed, instead of just evicted.  Collisions are linked
  99  *  using a PRCList to keep track of current generation number.
 100  *
 101  *  Used to detect hash number collisions, and find available generation numbers.
 102  *
 103  *  Not all nsDiskCacheBinding have a generation number.
 104  *
 105  *  Generation numbers may be aquired late, or lost (when data fits in block file)
 106  *
 107  *  Collisions can occur:
 108  *      BindEntry()       - hashnumbers collide (possibly different keys)
 109  *
 110  *  Generation number required:
 111  *      DeactivateEntry() - metadata written to disk, may require file
 112  *      GetFileForEntry() - force data to require file
 113  *      writing to stream - data size may require file
 114  *
 115  *  Binding can be kept in PRCList in order of generation numbers.
 116  *  Binding with no generation number can be Appended to PRCList (last).
 117  *
 118  *****************************************************************************/
 119
 120 class nsDiskCacheBindery {
 121 public:
 122     nsDiskCacheBindery();
 123     ~nsDiskCacheBindery();
 124
 125     nsresult                Init();
 126     void                    Reset();
 127
 128     nsDiskCacheBinding *    CreateBinding(nsCacheEntry *       entry,
 129                                           nsDiskCacheRecord *  record);
 130
 131     nsDiskCacheBinding *    FindActiveBinding(PRUint32  hashNumber);
 132     void                    RemoveBinding(nsDiskCacheBinding * binding);
 133     PRBool                  ActiveBindings();
 134
 135 private:
 136     nsresult                AddBinding(nsDiskCacheBinding * binding);
 137
 138     // member variables
 139     static PLDHashTableOps ops;
 140     PLDHashTable           table;
 141     PRBool                 initialized;
 142 };
 143
 144 #endif /* _nsDiskCacheBinding_h_ */