The Tor Browser: netwerk/cache/nsDiskCacheBinding.h@a63d609f5ebe

     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/. */

     8 #ifndef _nsDiskCacheBinding_h_

     9 #define _nsDiskCacheBinding_h_

    11 #include "mozilla/MemoryReporting.h"

    12 #include "nspr.h"

    13 #include "pldhash.h"

    15 #include "nsISupports.h"

    16 #include "nsCacheEntry.h"

    18 #include "nsDiskCacheMap.h"

    19 #include "nsDiskCacheStreams.h"

    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  *****************************************************************************/

    31 class nsDiskCacheDeviceDeactivateEntryEvent;

    33 class nsDiskCacheBinding : public nsISupports, public PRCList {

    34 public:

    35     NS_DECL_THREADSAFE_ISUPPORTS

    37     nsDiskCacheBinding(nsCacheEntry* entry, nsDiskCacheRecord * record);

    38     virtual ~nsDiskCacheBinding();

    40     nsresult EnsureStreamIO();

    41     bool     IsActive() { return mCacheEntry != nullptr;}

    43 // XXX make friends

    44 public:

    45     nsCacheEntry*           mCacheEntry;    // back pointer to parent nsCacheEntry

    46     nsDiskCacheRecord       mRecord;

    47     nsDiskCacheStreamIO*    mStreamIO;      // strong reference

    48     bool                    mDoomed;        // record is not stored in cache map

    49     uint8_t                 mGeneration;    // possibly just reservation

    51     // If set, points to a pending event which will deactivate |mCacheEntry|.

    52     // If not set then either |mCacheEntry| is not deactivated, or it has been

    53     // deactivated but the device returned it from FindEntry() before the event

    54     // fired. In both two latter cases this binding is to be considered valid.

    55     nsDiskCacheDeviceDeactivateEntryEvent *mDeactivateEvent;

    56 };

    59 /******************************************************************************

    60  *  Utility Functions

    61  *****************************************************************************/

    63 nsDiskCacheBinding *   GetCacheEntryBinding(nsCacheEntry * entry);

    67 /******************************************************************************

    68  *  nsDiskCacheBindery

    69  *

    70  *  Used to keep track of nsDiskCacheBinding associated with active/bound (and

    71  *  possibly doomed) entries.  Lookups on 4 byte disk hash to find collisions

    72  *  (which need to be doomed, instead of just evicted.  Collisions are linked

    73  *  using a PRCList to keep track of current generation number.

    74  *

    75  *  Used to detect hash number collisions, and find available generation numbers.

    76  *

    77  *  Not all nsDiskCacheBinding have a generation number.

    78  *

    79  *  Generation numbers may be aquired late, or lost (when data fits in block file)

    80  *

    81  *  Collisions can occur:

    82  *      BindEntry()       - hashnumbers collide (possibly different keys)

    83  *

    84  *  Generation number required:

    85  *      DeactivateEntry() - metadata written to disk, may require file

    86  *      GetFileForEntry() - force data to require file

    87  *      writing to stream - data size may require file

    88  *

    89  *  Binding can be kept in PRCList in order of generation numbers.

    90  *  Binding with no generation number can be Appended to PRCList (last).

    91  *

    92  *****************************************************************************/

    94 class nsDiskCacheBindery {

    95 public:

    96     nsDiskCacheBindery();

    97     ~nsDiskCacheBindery();

    99     nsresult                Init();

   100     void                    Reset();

   102     nsDiskCacheBinding *    CreateBinding(nsCacheEntry *       entry,

   103                                           nsDiskCacheRecord *  record);

   105     nsDiskCacheBinding *    FindActiveBinding(uint32_t  hashNumber);

   106     void                    RemoveBinding(nsDiskCacheBinding * binding);

   107     bool                    ActiveBindings();

   109     size_t                 SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf);

   111 private:

   112     nsresult                AddBinding(nsDiskCacheBinding * binding);

   114     // member variables

   115     static const PLDHashTableOps ops;

   116     PLDHashTable           table;

   117     bool                   initialized;

   118 };

   120 #endif /* _nsDiskCacheBinding_h_ */

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