bsd/hfs/hfscommon/headers/BTreeScanner.h

   1 /*
   2  * Copyright (c) 1996-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  *
  25  *      @(#)BTreeScanner.h
  26  */
  27
  28 #ifndef _BTREESCANNER_H_
  29 #define _BTREESCANNER_H_
  30
  31 #include <sys/appleapiopts.h>
  32
  33 #ifdef KERNEL
  34 #ifdef __APPLE_API_PRIVATE
  35 #include <sys/time.h>
  36
  37 #include "FileMgrInternal.h"
  38 #include "BTreesPrivate.h"
  39
  40 // amount of time we are allowed to process a catalog search (in µ secs)
  41 // NOTE - code assumes kMaxMicroSecsInKernel is less than 1,000,000
  42 // jertodo - what should we set this to?
  43 enum { kMaxMicroSecsInKernel = (1000 * 100) };  // 1 tenth of a second
  44
  45 // btree node scanner buffer size.  at 32K we get 8 nodes.  this is the size used
  46 // in Mac OS 9
  47 enum { kCatSearchBufferSize = (32 * 1024) };
  48
  49
  50 /*
  51  * ============ W A R N I N G ! ============
  52  * DO NOT INCREASE THE SIZE OF THIS STRUCT!
  53  * It must be less than or equal to the size of
  54  * the opaque searchstate struct (in sys/attr.h).
  55  */
  56 /* Private description used in hfs_search */
  57 struct CatPosition
  58 {
  59   u_int32_t             writeCount;     /* The BTree's write count (to see if the catalog writeCount */
  60                                 /* changed since the last search).  If 0, the rest */
  61                                 /* of the record is invalid, start from beginning. */
  62   u_int32_t     nextNode;       /* node number to resume search */
  63   u_int32_t     nextRecord;     /* record number to resume search */
  64   u_int32_t     recordsFound;   /* number of leaf records seen so far */
  65 };
  66 typedef struct CatPosition              CatPosition;
  67
  68
  69 /*
  70         BTScanState - This structure is used to keep track of the current state
  71         of a BTree scan.  It contains both the dynamic state information (like
  72         the current node number and record number) and information that is static
  73         for the duration of a scan (such as buffer pointers).
  74
  75         NOTE: recordNum may equal or exceed the number of records in the node
  76         number nodeNum.  If so, then the next attempt to get a record will move
  77         to a new node number.
  78 */
  79 struct BTScanState
  80 {
  81         //      The following fields are set up once at initialization time.
  82         //      They are not changed during a scan.
  83         u_int32_t                       bufferSize;
  84         struct buf *            bufferPtr;
  85         BTreeControlBlock *     btcb;
  86
  87         //      The following fields are the dynamic state of the current scan.
  88         u_int32_t                       nodeNum;                        // zero is first node
  89         u_int32_t                       recordNum;                      // zero is first record
  90         BTNodeDescriptor *      currentNodePtr;         // points to current node within buffer
  91         u_int32_t                       nodesLeftInBuffer;      // number of valid nodes still in the buffer
  92         u_int32_t                       recordsFound;           // number of leaf records seen so far
  93         struct timeval          startTime;                      // time we started catalog search
  94 };
  95 typedef struct BTScanState BTScanState;
  96
  97
  98 /* *********************** PROTOTYPES *********************** */
  99
 100 int     BTScanInitialize(       const FCB *             btreeFile,
 101                                                 u_int32_t               startingNode,
 102                                                 u_int32_t               startingRecord,
 103                                                 u_int32_t               recordsFound,
 104                                                 u_int32_t               bufferSize,
 105                                                 BTScanState     *       scanState     );
 106
 107 int BTScanNextRecord(   BTScanState *   scanState,
 108                                                 Boolean                 avoidIO,
 109                                                 void * *                key,
 110                                                 void * *                data,
 111                                                 u_int32_t *             dataSize  );
 112
 113 int     BTScanTerminate(        BTScanState *   scanState,
 114                                                 u_int32_t *             startingNode,
 115                                                 u_int32_t *             startingRecord,
 116                                                 u_int32_t *             recordsFound    );
 117
 118 #endif /* __APPLE_API_PRIVATE */
 119 #endif /* KERNEL */
 120 #endif /* !_BTREESCANNER_H_ */