core/BTreeScanner.h

   1 /*
   2  * Copyright (c) 1996-2004 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  *
  28  *      @(#)BTreeScanner.h
  29  */
  30
  31 #ifndef _BTREESCANNER_H_
  32 #define _BTREESCANNER_H_
  33
  34 #include <sys/appleapiopts.h>
  35
  36 #ifdef KERNEL
  37 #ifdef __APPLE_API_PRIVATE
  38 #include <sys/time.h>
  39
  40 #include "FileMgrInternal.h"
  41 #include "BTreesPrivate.h"
  42
  43 // amount of time we are allowed to process a catalog search (in µ secs)
  44 // NOTE - code assumes kMaxMicroSecsInKernel is less than 1,000,000
  45 enum { kMaxMicroSecsInKernel = (1000 * 100) };  // 1 tenth of a second
  46
  47 // btree node scanner buffer size.  at 32K we get 8 nodes.  this is the size used
  48 // in Mac OS 9
  49 enum { kCatSearchBufferSize = (32 * 1024) };
  50
  51
  52 /*
  53  * ============ W A R N I N G ! ============
  54  * DO NOT INCREASE THE SIZE OF THIS STRUCT!
  55  * It must be less than or equal to the size of
  56  * the opaque searchstate struct (in sys/attr.h).
  57  */
  58 /* Private description used in hfs_search */
  59 struct CatPosition
  60 {
  61   u_int32_t             writeCount;     /* The BTree's write count (to see if the catalog writeCount */
  62                                 /* changed since the last search).  If 0, the rest */
  63                                 /* of the record is invalid, start from beginning. */
  64   u_int32_t     nextNode;       /* node number to resume search */
  65   u_int32_t     nextRecord;     /* record number to resume search */
  66   u_int32_t     recordsFound;   /* number of leaf records seen so far */
  67 };
  68 typedef struct CatPosition              CatPosition;
  69
  70
  71 /*
  72         BTScanState - This structure is used to keep track of the current state
  73         of a BTree scan.  It contains both the dynamic state information (like
  74         the current node number and record number) and information that is static
  75         for the duration of a scan (such as buffer pointers).
  76
  77         NOTE: recordNum may equal or exceed the number of records in the node
  78         number nodeNum.  If so, then the next attempt to get a record will move
  79         to a new node number.
  80 */
  81 struct BTScanState
  82 {
  83         //      The following fields are set up once at initialization time.
  84         //      They are not changed during a scan.
  85         u_int32_t                       bufferSize;
  86         struct buf *            bufferPtr;
  87         BTreeControlBlock *     btcb;
  88
  89         //      The following fields are the dynamic state of the current scan.
  90         u_int32_t                       nodeNum;                        // zero is first node
  91         u_int32_t                       recordNum;                      // zero is first record
  92         BTNodeDescriptor *      currentNodePtr;         // points to current node within buffer
  93         u_int32_t                       nodesLeftInBuffer;      // number of valid nodes still in the buffer
  94         u_int32_t                       recordsFound;           // number of leaf records seen so far
  95         struct timeval          startTime;                      // time we started catalog search
  96 };
  97 typedef struct BTScanState BTScanState;
  98
  99
 100 /* *********************** PROTOTYPES *********************** */
 101
 102 int     BTScanInitialize(       const FCB *             btreeFile,
 103                                                 u_int32_t               startingNode,
 104                                                 u_int32_t               startingRecord,
 105                                                 u_int32_t               recordsFound,
 106                                                 u_int32_t               bufferSize,
 107                                                 BTScanState     *       scanState     );
 108
 109 int BTScanNextRecord(   BTScanState *   scanState,
 110                                                 Boolean                 avoidIO,
 111                                                 void * *                key,
 112                                                 void * *                data,
 113                                                 u_int32_t *             dataSize  );
 114
 115 int     BTScanTerminate(        BTScanState *   scanState,
 116                                                 u_int32_t *             startingNode,
 117                                                 u_int32_t *             startingRecord,
 118                                                 u_int32_t *             recordsFound    );
 119
 120 #endif /* __APPLE_API_PRIVATE */
 121 #endif /* KERNEL */
 122 #endif /* !_BTREESCANNER_H_ */