bsd/hfs/hfscommon/headers/BTreeScanner.h

   1 /*
   2  * Copyright (c) 1996-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  *
  23  *      @(#)BTreeScanner.h
  24  */
  25
  26 #ifndef _BTREESCANNER_H_
  27 #define _BTREESCANNER_H_
  28
  29 #include <sys/appleapiopts.h>
  30
  31 #ifdef KERNEL
  32 #ifdef __APPLE_API_PRIVATE
  33 #include <sys/time.h>
  34
  35 #include "FileMgrInternal.h"
  36 #include "BTreesPrivate.h"
  37
  38 // amount of time we are allowed to process a catalog search (in µ secs)
  39 // NOTE - code assumes kMaxMicroSecsInKernel is less than 1,000,000
  40 enum { kMaxMicroSecsInKernel = (1000 * 100) };  // 1 tenth of a second
  41
  42 // btree node scanner buffer size.  at 32K we get 8 nodes.  this is the size used
  43 // in Mac OS 9
  44 enum { kCatSearchBufferSize = (32 * 1024) };
  45
  46
  47 /*
  48  * ============ W A R N I N G ! ============
  49  * DO NOT INCREASE THE SIZE OF THIS STRUCT!
  50  * It must be less than or equal to the size of
  51  * the opaque searchstate struct (in sys/attr.h).
  52  */
  53 /* Private description used in hfs_search */
  54 struct CatPosition
  55 {
  56   u_int32_t             writeCount;     /* The BTree's write count (to see if the catalog writeCount */
  57                                 /* changed since the last search).  If 0, the rest */
  58                                 /* of the record is invalid, start from beginning. */
  59   u_int32_t     nextNode;       /* node number to resume search */
  60   u_int32_t     nextRecord;     /* record number to resume search */
  61   u_int32_t     recordsFound;   /* number of leaf records seen so far */
  62 };
  63 typedef struct CatPosition              CatPosition;
  64
  65
  66 /*
  67         BTScanState - This structure is used to keep track of the current state
  68         of a BTree scan.  It contains both the dynamic state information (like
  69         the current node number and record number) and information that is static
  70         for the duration of a scan (such as buffer pointers).
  71
  72         NOTE: recordNum may equal or exceed the number of records in the node
  73         number nodeNum.  If so, then the next attempt to get a record will move
  74         to a new node number.
  75 */
  76 struct BTScanState
  77 {
  78         //      The following fields are set up once at initialization time.
  79         //      They are not changed during a scan.
  80         u_int32_t                       bufferSize;
  81         struct buf *            bufferPtr;
  82         BTreeControlBlock *     btcb;
  83
  84         //      The following fields are the dynamic state of the current scan.
  85         u_int32_t                       nodeNum;                        // zero is first node
  86         u_int32_t                       recordNum;                      // zero is first record
  87         BTNodeDescriptor *      currentNodePtr;         // points to current node within buffer
  88         u_int32_t                       nodesLeftInBuffer;      // number of valid nodes still in the buffer
  89         u_int32_t                       recordsFound;           // number of leaf records seen so far
  90         struct timeval          startTime;                      // time we started catalog search
  91 };
  92 typedef struct BTScanState BTScanState;
  93
  94
  95 /* *********************** PROTOTYPES *********************** */
  96
  97 int     BTScanInitialize(       const FCB *             btreeFile,
  98                                                 u_int32_t               startingNode,
  99                                                 u_int32_t               startingRecord,
 100                                                 u_int32_t               recordsFound,
 101                                                 u_int32_t               bufferSize,
 102                                                 BTScanState     *       scanState     );
 103
 104 int BTScanNextRecord(   BTScanState *   scanState,
 105                                                 Boolean                 avoidIO,
 106                                                 void * *                key,
 107                                                 void * *                data,
 108                                                 u_int32_t *             dataSize  );
 109
 110 int     BTScanTerminate(        BTScanState *   scanState,
 111                                                 u_int32_t *             startingNode,
 112                                                 u_int32_t *             startingRecord,
 113                                                 u_int32_t *             recordsFound    );
 114
 115 #endif /* __APPLE_API_PRIVATE */
 116 #endif /* KERNEL */
 117 #endif /* !_BTREESCANNER_H_ */