sys/vfs/hammer/hammer_cursor.h

   1 /*
   2  * Copyright (c) 2007 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/vfs/hammer/hammer_cursor.h,v 1.7 2008/01/17 05:06:09 dillon Exp $
  35  */
  36
  37 /*
  38  * The hammer_cursor structure is the primary in-memory management structure
  39  * for B-Tree operations.
  40  *
  41  * The most important issue to make note of is that a hammer_cursor is a
  42  * tracking structure.  Any active hammer_cursor structure will be linked into
  43  * hammer_node based lists and B-Tree operations executed by unrelated
  44  * treads MAY MODIFY YOUR CURSOR when you are not holding an exclusive
  45  * lock on the cursor's nodes.
  46  *
  47  * Most operations maintain an exclusive lock on their node and
  48  * parent node, but certain cursor operations may temporarily release
  49  * one or both locks.  In particular, a cursor_up operation may have
  50  * to temporarily release underlying locks to avoid a deadlock.
  51  */
  52 struct hammer_cursor {
  53         /*
  54          * Parent B-Tree node, current B-Tree node, and related element
  55          * indices.
  56          */
  57         hammer_node_t parent;
  58         int parent_index;
  59         hammer_node_t node;
  60         int index;
  61
  62         /*
  63          * Pointer to the current node's bounds.  Typically points to the
  64          * appropriate boundary elements in the parent or points to bounds
  65          * stored in the cluster.  The right-boundary is range-exclusive.
  66          */
  67         hammer_base_elm_t left_bound;
  68         hammer_base_elm_t right_bound;
  69
  70         /*
  71          * Key or key range governing search.  The cursor code may adjust
  72          * key_beg/key_end if asof is non-zero.
  73          */
  74         struct hammer_base_elm key_beg;
  75         struct hammer_base_elm key_end;
  76         hammer_tid_t    asof;
  77
  78         /*
  79          * Related data and record references.  Note that the related buffers
  80          * can be NULL when data and/or record is not, typically indicating
  81          * information referenced via an in-memory record.
  82          */
  83         struct hammer_buffer *data_buffer;      /* extracted data & record */
  84         union hammer_data_ondisk *data;
  85         struct hammer_buffer *record_buffer;
  86         union hammer_record_ondisk *record;
  87
  88         /*
  89          * Iteration and extraction control variables
  90          */
  91         int flags;
  92
  93         /*
  94          * Merged in-memory/on-disk iterations also use these fields.
  95          */
  96         struct hammer_inode *ip;
  97         struct hammer_record *iprec;
  98         struct hammer_rec_rb_tree_scan_info scan;
  99 };
 100
 101 typedef struct hammer_cursor *hammer_cursor_t;
 102
 103 #define HAMMER_CURSOR_GET_RECORD        0x0001
 104 #define HAMMER_CURSOR_GET_DATA          0x0002
 105 #define HAMMER_CURSOR_INCLUSTER         0x0004  /* stay in the cluster */
 106 #define HAMMER_CURSOR_INSERT            0x0008  /* adjust for insert */
 107 #define HAMMER_CURSOR_DELETE            0x0010  /* adjust for delete */
 108 #define HAMMER_CURSOR_END_INCLUSIVE     0x0020  /* key_end is inclusive */
 109 #define HAMMER_CURSOR_END_EXCLUSIVE     0x0040  /* key_end is exclusive (def) */
 110
 111 #define HAMMER_CURSOR_ATEDISK           0x0100
 112 #define HAMMER_CURSOR_ATEMEM            0x0200
 113 #define HAMMER_CURSOR_DISKEOF           0x0400
 114 #define HAMMER_CURSOR_MEMEOF            0x0800
 115 #define HAMMER_CURSOR_DELBTREE          0x1000  /* ip_delete from b-tree */
 116 #define HAMMER_CURSOR_DATA_EMBEDDED     0x2000  /* embedded flag on extract */
 117 #define HAMMER_CURSOR_ASOF              0x4000  /* as-of lookup */
 118