summaryrefslogtreecommitdiff
path: root/src/quicklist.h
blob: b9c01757d312e5c95be9cc6bfdaa82b2b4531f8b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
/* quicklist.h - A generic doubly linked quicklist implementation
 *
 * Copyright (c) 2014, Matt Stancliff <matt@genges.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this quicklist of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this quicklist of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdint.h> // for UINTPTR_MAX

#ifndef __QUICKLIST_H__
#define __QUICKLIST_H__

/* Node, quicklist, and Iterator are the only data structures used currently. */

/* quicklistNode is a 32 byte struct describing a ziplist for a quicklist.
 * We use bit fields keep the quicklistNode at 32 bytes.
 * count: 16 bits, max 65536 (max zl bytes is 65k, so max count actually < 32k).
 * encoding: 2 bits, RAW=1, LZF=2.
 * container: 2 bits, NONE=1, ZIPLIST=2.
 * recompress: 1 bit, bool, true if node is temporary decompressed for usage.
 * attempted_compress: 1 bit, boolean, used for verifying during testing.
 * extra: 10 bits, free for future use; pads out the remainder of 32 bits */
typedef struct quicklistNode {
    struct quicklistNode *prev;
    struct quicklistNode *next;
    unsigned char *zl;
    unsigned int sz;             /* ziplist size in bytes */
    unsigned int count : 16;     /* count of items in ziplist */
    unsigned int encoding : 2;   /* RAW==1 or LZF==2 */
    unsigned int container : 2;  /* NONE==1 or ZIPLIST==2 */
    unsigned int recompress : 1; /* was this node previous compressed? */
    unsigned int attempted_compress : 1; /* node can't compress; too small */
    unsigned int extra : 10; /* more bits to steal for future usage */
} quicklistNode;

/* quicklistLZF is a 4+N byte struct holding 'sz' followed by 'compressed'.
 * 'sz' is byte length of 'compressed' field.
 * 'compressed' is LZF data with total (compressed) length 'sz'
 * NOTE: uncompressed length is stored in quicklistNode->sz.
 * When quicklistNode->zl is compressed, node->zl points to a quicklistLZF */
typedef struct quicklistLZF {
    unsigned int sz; /* LZF size in bytes*/
    char compressed[];
} quicklistLZF;

/* Bookmarks are padded with realloc at the end of of the quicklist struct.
 * They should only be used for very big lists if thousands of nodes were the
 * excess memory usage is negligible, and there's a real need to iterate on them
 * in portions.
 * When not used, they don't add any memory overhead, but when used and then
 * deleted, some overhead remains (to avoid resonance).
 * The number of bookmarks used should be kept to minimum since it also adds
 * overhead on node deletion (searching for a bookmark to update). */
typedef struct quicklistBookmark {
    quicklistNode *node;
    char *name;
} quicklistBookmark;

#if UINTPTR_MAX == 0xffffffff
/* 32-bit */
#   define QL_FILL_BITS 14
#   define QL_COMP_BITS 14
#   define QL_BM_BITS 4
#elif UINTPTR_MAX == 0xffffffffffffffff
/* 64-bit */
#   define QL_FILL_BITS 16
#   define QL_COMP_BITS 16
#   define QL_BM_BITS 4 /* we can encode more, but we rather limit the user
                           since they cause performance degradation. */
#else
#   error unknown arch bits count
#endif

/* quicklist is a 40 byte struct (on 64-bit systems) describing a quicklist.
 * 'count' is the number of total entries.
 * 'len' is the number of quicklist nodes.
 * 'compress' is: 0 if compression disabled, otherwise it's the number
 *                of quicklistNodes to leave uncompressed at ends of quicklist.
 * 'fill' is the user-requested (or default) fill factor.
 * 'bookmarks are an optional feature that is used by realloc this struct,
 *      so that they don't consume memory when not used. */
typedef struct quicklist {
    quicklistNode *head;
    quicklistNode *tail;
    unsigned long count;        /* total count of all entries in all ziplists */
    unsigned long len;          /* number of quicklistNodes */
    int fill : QL_FILL_BITS;              /* fill factor for individual nodes */
    unsigned int compress : QL_COMP_BITS; /* depth of end nodes not to compress;0=off */
    unsigned int bookmark_count: QL_BM_BITS;
    quicklistBookmark bookmarks[];
} quicklist;

typedef struct quicklistIter {
    const quicklist *quicklist;
    quicklistNode *current;
    unsigned char *zi;
    long offset; /* offset in current ziplist */
    int direction;
} quicklistIter;

typedef struct quicklistEntry {
    const quicklist *quicklist;
    quicklistNode *node;
    unsigned char *zi;
    unsigned char *value;
    long long longval;
    unsigned int sz;
    int offset;
} quicklistEntry;

#define QUICKLIST_HEAD 0
#define QUICKLIST_TAIL -1

/* quicklist node encodings */
#define QUICKLIST_NODE_ENCODING_RAW 1
#define QUICKLIST_NODE_ENCODING_LZF 2

/* quicklist compression disable */
#define QUICKLIST_NOCOMPRESS 0

/* quicklist container formats */
#define QUICKLIST_NODE_CONTAINER_NONE 1
#define QUICKLIST_NODE_CONTAINER_ZIPLIST 2

#define quicklistNodeIsCompressed(node)                                        \
    ((node)->encoding == QUICKLIST_NODE_ENCODING_LZF)

/* Prototypes */
quicklist *quicklistCreate(void);
quicklist *quicklistNew(int fill, int compress);
void quicklistSetCompressDepth(quicklist *quicklist, int depth);
void quicklistSetFill(quicklist *quicklist, int fill);
void quicklistSetOptions(quicklist *quicklist, int fill, int depth);
void quicklistRelease(quicklist *quicklist);
int quicklistPushHead(quicklist *quicklist, void *value, const size_t sz);
int quicklistPushTail(quicklist *quicklist, void *value, const size_t sz);
void quicklistPush(quicklist *quicklist, void *value, const size_t sz,
                   int where);
void quicklistAppendZiplist(quicklist *quicklist, unsigned char *zl);
quicklist *quicklistAppendValuesFromZiplist(quicklist *quicklist,
                                            unsigned char *zl);
quicklist *quicklistCreateFromZiplist(int fill, int compress,
                                      unsigned char *zl);
void quicklistInsertAfter(quicklist *quicklist, quicklistEntry *entry,
                          void *value, const size_t sz);
void quicklistInsertBefore(quicklist *quicklist, quicklistEntry *entry,
                           void *value, const size_t sz);
void quicklistDelEntry(quicklistIter *iter, quicklistEntry *entry);
int quicklistReplaceAtIndex(quicklist *quicklist, long index, void *data,
                            int sz);
int quicklistDelRange(quicklist *quicklist, const long start, const long stop);
quicklistIter *quicklistGetIterator(const quicklist *quicklist, int direction);
quicklistIter *quicklistGetIteratorAtIdx(const quicklist *quicklist,
                                         int direction, const long long idx);
int quicklistNext(quicklistIter *iter, quicklistEntry *entry);
void quicklistReleaseIterator(quicklistIter *iter);
quicklist *quicklistDup(quicklist *orig);
int quicklistIndex(const quicklist *quicklist, const long long index,
                   quicklistEntry *entry);
void quicklistRotate(quicklist *quicklist);
int quicklistPopCustom(quicklist *quicklist, int where, unsigned char **data,
                       unsigned int *sz, long long *sval,
                       void *(*saver)(unsigned char *data, unsigned int sz));
int quicklistPop(quicklist *quicklist, int where, unsigned char **data,
                 unsigned int *sz, long long *slong);
unsigned long quicklistCount(const quicklist *ql);
int quicklistCompare(unsigned char *p1, unsigned char *p2, int p2_len);
size_t quicklistGetLzf(const quicklistNode *node, void **data);

/* bookmarks */
int quicklistBookmarkCreate(quicklist **ql_ref, const char *name, quicklistNode *node);
int quicklistBookmarkDelete(quicklist *ql, const char *name);
quicklistNode *quicklistBookmarkFind(quicklist *ql, const char *name);
void quicklistBookmarksClear(quicklist *ql);

#ifdef REDIS_TEST
int quicklistTest(int argc, char *argv[], int accurate);
#endif

/* Directions for iterators */
#define AL_START_HEAD 0
#define AL_START_TAIL 1

#endif /* __QUICKLIST_H__ */