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 1.26 2008/08/06 15:38:58 dillon Exp $
  35  */
  36
  37 struct hammer_cmirror;
  38
  39 /*
  40  * The hammer_cursor structure is the primary in-memory management structure
  41  * for B-Tree operations.
  42  *
  43  * The most important issue to make note of is that a hammer_cursor is a
  44  * tracking structure.  Any active hammer_cursor structure will be linked into
  45  * hammer_node based lists and B-Tree operations executed by unrelated
  46  * treads MAY MODIFY YOUR CURSOR when you are not holding an exclusive
  47  * lock on the cursor's nodes.
  48  *
  49  * The cursor module maintains a shared lock on cursor->node and
  50  * cursor->parent.
  51  */
  52 struct hammer_cursor {
  53         /*
  54          * Parent B-Tree node, current B-Tree node, and related element
  55          * indices.
  56          */
  57         hammer_transaction_t trans;
  58         hammer_node_t   parent;
  59         int             parent_index;
  60
  61         hammer_node_t   node;
  62         int             index;
  63
  64         /*
  65          * Set if a deadlock occurs.  hammer_done_cursor() will block on
  66          * this after releasing parent and node, before returning.  See
  67          * also hammer_recover_cursor().
  68          */
  69         TAILQ_ENTRY(hammer_cursor) deadlk_entry;
  70         hammer_node_t deadlk_node;
  71         hammer_record_t deadlk_rec;
  72
  73         /*
  74          * Set along with HAMMER_CURSOR_CREATE_CHECK when doing an as-of
  75          * search.  If ENOENT is returned and the flag is set, the caller
  76          * must iterate with a new delete_tid.
  77          */
  78         hammer_tid_t  create_check;
  79
  80         /*
  81          * Pointer to the current node's bounds.  Typically points to the
  82          * appropriate boundary elements in the parent or points to bounds
  83          * stored in the cluster.  The right-boundary is range-exclusive.
  84          */
  85         hammer_base_elm_t left_bound;
  86         hammer_base_elm_t right_bound;
  87
  88         /*
  89          * Key or key range governing search.  The cursor code may adjust
  90          * key_beg/key_end if asof is non-zero.
  91          */
  92         struct hammer_base_elm key_beg;
  93         struct hammer_base_elm key_end;
  94         hammer_tid_t    asof;
  95         struct hammer_cmirror *cmirror;
  96
  97         /*
  98          * Related data and record references.  Note that the related buffers
  99          * can be NULL when data and/or record is not, typically indicating
 100          * information referenced via an in-memory record.
 101          */
 102         struct hammer_buffer *data_buffer;      /* extended data */
 103         struct hammer_btree_leaf_elm *leaf;
 104         union hammer_data_ondisk *data;
 105
 106         /*
 107          * Iteration and extraction control variables
 108          */
 109         int flags;
 110         int rec_generation;
 111
 112         /*
 113          * Merged in-memory/on-disk iterations also use these fields.
 114          */
 115         struct hammer_inode *ip;
 116         struct hammer_record *iprec;
 117 };
 118
 119 typedef struct hammer_cursor *hammer_cursor_t;
 120
 121 #define HAMMER_CURSOR_GET_LEAF          0x0001
 122 #define HAMMER_CURSOR_GET_DATA          0x0002
 123 #define HAMMER_CURSOR_BACKEND           0x0004  /* cursor run by backend */
 124 #define HAMMER_CURSOR_INSERT            0x0008  /* adjust for insert */
 125 #define HAMMER_CURSOR_DELETE_VISIBILITY 0x0010  /* special del-on-disk recs */
 126 #define HAMMER_CURSOR_END_INCLUSIVE     0x0020  /* key_end is inclusive */
 127 #define HAMMER_CURSOR_END_EXCLUSIVE     0x0040  /* key_end is exclusive (def) */
 128
 129 #define HAMMER_CURSOR_ATEDISK           0x0100
 130 #define HAMMER_CURSOR_ATEMEM            0x0200
 131 #define HAMMER_CURSOR_DISKEOF           0x0400
 132 #define HAMMER_CURSOR_MEMEOF            0x0800
 133 #define HAMMER_CURSOR_RETEST            0x1000  /* retest current element */
 134 #define HAMMER_CURSOR_MIRROR_FILTERED   0x2000  /* mirror_tid filter */
 135 #define HAMMER_CURSOR_ASOF              0x4000  /* as-of lookup */
 136 #define HAMMER_CURSOR_CREATE_CHECK      0x8000  /* as-of lookup */
 137
 138 #define HAMMER_CURSOR_PRUNING           0x00010000
 139 #define HAMMER_CURSOR_REBLOCKING        0x00020000
 140 #define HAMMER_CURSOR_TRACKED           0x00040000
 141 #define HAMMER_CURSOR_TRACKED_RIPOUT    0x00080000
 142 #define HAMMER_CURSOR_LASTWASMEM        0x00100000 /* hammer_ip_next logic */
 143
 144 /*
 145  * Flags we can clear when reusing a cursor (we can clear all of them)
 146  */
 147 #define HAMMER_CURSOR_INITMASK          (~0)
 148
 149 /*
 150  * Mirror scan extension structure.  Caller sets mirror_tid to restrict
 151  * the scan.  If the iteration is able to skip one or more internal nodes
 152  * it returns an internal node with skip_beg/end set to the skipped range.
 153  *
 154  * If the first element of an internal node is skipped skip_beg will use
 155  * the left_bound inherited from the parent, and the same for the last
 156  * element.  This is because gaps can develop in the bounds.
 157  */
 158 struct hammer_cmirror {
 159         hammer_tid_t    mirror_tid;
 160         struct hammer_base_elm skip_beg;
 161         struct hammer_base_elm skip_end;
 162 };
 163
 164 /*
 165  * NOTE: iprec can be NULL, but the address-of does not indirect through
 166  * it so we are ok.
 167  */
 168 #define hammer_cursor_inmem(cursor)             \
 169                         ((cursor)->leaf == &(cursor)->iprec->leaf)
 170 #define hammer_cursor_ondisk(cursor)            \
 171                         ((cursor)->leaf != &(cursor)->iprec->leaf)
 172