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>
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34 * $DragonFly: src/sys/vfs/hammer/hammer_cursor.h,v 1.26 2008/08/06 15:38:58 dillon Exp $
37 #ifndef VFS_HAMMER_CURSOR_H_
38 #define VFS_HAMMER_CURSOR_H_
41 * The hammer_cursor structure is the primary in-memory management structure
42 * for B-Tree operations.
44 * The most important issue to make note of is that a hammer_cursor is a
45 * tracking structure. Any active hammer_cursor structure will be linked into
46 * hammer_node based lists and B-Tree operations executed by unrelated
47 * treads MAY MODIFY YOUR CURSOR when you are not holding an exclusive
48 * lock on the cursor's nodes.
50 * The cursor module maintains a shared lock on cursor->node and
53 typedef struct hammer_cursor {
55 * Parent B-Tree node, current B-Tree node, and related element
58 hammer_transaction_t trans;
66 * Set if a deadlock occurs. hammer_done_cursor() will block on
67 * this after releasing parent and node, before returning. See
68 * also hammer_recover_cursor().
70 TAILQ_ENTRY(hammer_cursor) deadlk_entry;
71 hammer_node_t deadlk_node;
72 hammer_record_t deadlk_rec;
75 * Set along with HAMMER_CURSOR_CREATE_CHECK when doing an as-of
76 * search. If ENOENT is returned and the flag is set, the caller
77 * must iterate with a new delete_tid.
79 hammer_tid_t create_check;
82 * Pointer to the current node's bounds. Typically points to the
83 * appropriate boundary elements in the parent.
84 * The right-boundary is range-exclusive.
86 hammer_base_elm_t left_bound;
87 hammer_base_elm_t right_bound;
90 * Key or key range governing search. The cursor code may adjust
91 * key_beg/key_end if asof is non-zero.
93 struct hammer_base_elm key_beg;
94 struct hammer_base_elm key_end;
96 struct hammer_cmirror *cmirror;
99 * Related data and record references. Note that the related buffers
100 * can be NULL when data and/or record is not, typically indicating
101 * information referenced via an in-memory record.
103 hammer_buffer_t data_buffer; /* extended data */
104 hammer_btree_leaf_elm_t leaf;
105 hammer_data_ondisk_t data;
108 * Iteration and extraction control variables
114 * Merged in-memory/on-disk iterations also use these fields.
117 hammer_record_t iprec;
120 #define HAMMER_CURSOR_GET_LEAF 0x0001 /* not used */
121 #define HAMMER_CURSOR_GET_DATA 0x0002
122 #define HAMMER_CURSOR_BACKEND 0x0004 /* cursor run by backend */
123 #define HAMMER_CURSOR_INSERT 0x0008 /* adjust for insert */
124 #define HAMMER_CURSOR_DELETE_VISIBILITY 0x0010 /* special del-on-disk recs */
125 #define HAMMER_CURSOR_END_INCLUSIVE 0x0020 /* key_end is inclusive */
126 #define HAMMER_CURSOR_END_EXCLUSIVE 0x0040 /* key_end is exclusive (def) */
128 #define HAMMER_CURSOR_ATEDISK 0x0100
129 #define HAMMER_CURSOR_ATEMEM 0x0200
130 #define HAMMER_CURSOR_DISKEOF 0x0400
131 #define HAMMER_CURSOR_MEMEOF 0x0800
132 #define HAMMER_CURSOR_RETEST 0x1000 /* retest current element */
133 #define HAMMER_CURSOR_MIRROR_FILTERED 0x2000 /* mirror_tid filter */
134 #define HAMMER_CURSOR_ASOF 0x4000 /* as-of lookup */
135 #define HAMMER_CURSOR_CREATE_CHECK 0x8000 /* as-of lookup */
137 #define HAMMER_CURSOR_PRUNING 0x00010000
138 #define HAMMER_CURSOR_REBLOCKING 0x00020000
139 #define HAMMER_CURSOR_TRACKED 0x00040000
140 #define HAMMER_CURSOR_TRACKED_RIPOUT 0x00080000
141 #define HAMMER_CURSOR_LASTWASMEM 0x00100000 /* hammer_ip_next logic */
142 #define HAMMER_CURSOR_ITERATE_CHECK 0x00200000
143 #define HAMMER_CURSOR_NOSWAPCACHE 0x00400000 /* applies to LARGE_DATA */
146 * Flags we can clear when reusing a cursor (we can clear all of them)
148 #define HAMMER_CURSOR_INITMASK (~0)
151 * Mirror scan extension structure. Caller sets mirror_tid to restrict
152 * the scan. If the iteration is able to skip one or more internal nodes
153 * it returns an internal node with skip_beg/end set to the skipped range.
155 * If the first element of an internal node is skipped skip_beg will use
156 * the left_bound inherited from the parent, and the same for the last
157 * element. This is because gaps can develop in the bounds.
159 struct hammer_cmirror {
160 hammer_tid_t mirror_tid;
161 struct hammer_base_elm skip_beg;
162 struct hammer_base_elm skip_end;
166 * NOTE: iprec can be NULL, but the address-of does not indirect through
169 #define hammer_cursor_inmem(cursor) \
170 ((cursor)->leaf == &(cursor)->iprec->leaf)
171 #define hammer_cursor_ondisk(cursor) \
172 ((cursor)->leaf != &(cursor)->iprec->leaf)
174 #endif /* !VFS_HAMMER_CURSOR_H_ */