2 * Copyright (c) 2007 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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
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.
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
34 * $DragonFly: src/sys/vfs/hammer/hammer_cursor.h,v 1.5 2007/12/29 09:01:27 dillon Exp $
38 * The hammer_cursor structure is the primary in-memory management structure
39 * for B-Tree operations.
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.
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.
52 struct hammer_cursor {
54 * Parent B-Tree node, current B-Tree node, and related element
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.
67 hammer_base_elm_t left_bound;
68 hammer_base_elm_t right_bound;
71 * Key or key range governing search
73 struct hammer_base_elm key_beg;
74 struct hammer_base_elm key_end;
77 * Related data and record references. Note that the related buffers
78 * can be NULL when data and/or record is not, typically indicating
79 * information referenced via an in-memory record.
81 struct hammer_buffer *data_buffer; /* extracted data & record */
82 union hammer_data_ondisk *data;
83 struct hammer_buffer *record_buffer;
84 union hammer_record_ondisk *record;
87 * Iteration and extraction control variables
92 * Merged in-memory/on-disk iterations also use these fields.
94 struct hammer_inode *ip;
95 struct hammer_record *iprec;
96 struct hammer_rec_rb_tree_scan_info scan;
99 typedef struct hammer_cursor *hammer_cursor_t;
101 #define HAMMER_CURSOR_GET_RECORD 0x0001
102 #define HAMMER_CURSOR_GET_DATA 0x0002
103 #define HAMMER_CURSOR_INCLUSTER 0x0004 /* stay in the cluster */
104 #define HAMMER_CURSOR_INSERT 0x0008 /* adjust for insert */
105 #define HAMMER_CURSOR_DELETE 0x0010 /* adjust for delete */
106 #define HAMMER_CURSOR_END_INCLUSIVE 0x0020 /* key_end is inclusive */
107 #define HAMMER_CURSOR_END_EXCLUSIVE 0x0040 /* key_end is exclusive (def) */
108 #define HAMMER_CURSOR_ALLHISTORY 0x0080 /* return entire history */
110 #define HAMMER_CURSOR_ATEDISK 0x0100
111 #define HAMMER_CURSOR_ATEMEM 0x0200
112 #define HAMMER_CURSOR_DISKEOF 0x0400
113 #define HAMMER_CURSOR_MEMEOF 0x0800
114 #define HAMMER_CURSOR_DELBTREE 0x1000 /* ip_delete from b-tree */
115 #define HAMMER_CURSOR_DATA_EMBEDDED 0x2000 /* embedded flag on extract */