Repository navigation
Expand file tree
/
Copy pathpcache.h
More file actions
161 lines (130 loc) · 5.6 KB
/
Copy pathpcache.h
File metadata and controls
161 lines (130 loc) · 5.6 KB
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
/*
** 2008 August 05
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.
*/
#ifndef _PCACHE_H_
typedef struct PgHdr PgHdr;
typedef struct PCache PCache;
/*
** Every page in the cache is controlled by an instance of the following
** structure.
*/
struct PgHdr {
sqlite3_pcache_page *pPage; /* Pcache object page handle */
void *pData; /* Page data */
void *pExtra; /* Extra content */
PgHdr *pDirty; /* Transient list of dirty pages */
Pager *pPager; /* The pager this page is part of */
Pgno pgno; /* Page number for this page */
#ifdef SQLITE_CHECK_PAGES
u32 pageHash; /* Hash of page content */
#endif
u16 flags; /* PGHDR flags defined below */
/**********************************************************************
** Elements above are public. All that follows is private to pcache.c
** and should not be accessed by other modules.
*/
i16 nRef; /* Number of users of this page */
PCache *pCache; /* Cache that owns this page */
PgHdr *pDirtyNext; /* Next element in list of dirty pages */
PgHdr *pDirtyPrev; /* Previous element in list of dirty pages */
};
/* Bit values for PgHdr.flags */
#define PGHDR_DIRTY 0x002 /* Page has changed */
#define PGHDR_NEED_SYNC 0x004 /* Fsync the rollback journal before
** writing this page to the database */
#define PGHDR_NEED_READ 0x008 /* Content is unread */
#define PGHDR_REUSE_UNLIKELY 0x010 /* A hint that reuse is unlikely */
#define PGHDR_DONT_WRITE 0x020 /* Do not write content to disk */
#define PGHDR_MMAP 0x040 /* This is an mmap page object */
/* Initialize and shutdown the page cache subsystem */
int sqlite3PcacheInitialize(void);
void sqlite3PcacheShutdown(void);
/* Page cache buffer management:
** These routines implement SQLITE_CONFIG_PAGECACHE.
*/
void sqlite3PCacheBufferSetup(void *, int sz, int n);
/* Create a new pager cache.
** Under memory stress, invoke xStress to try to make pages clean.
** Only clean and unpinned pages can be reclaimed.
*/
void sqlite3PcacheOpen(
int szPage, /* Size of every page */
int szExtra, /* Extra space associated with each page */
int bPurgeable, /* True if pages are on backing store */
int (*xStress)(void*, PgHdr*), /* Call to try to make pages clean */
void *pStress, /* Argument to xStress */
PCache *pToInit /* Preallocated space for the PCache */
);
/* Modify the page-size after the cache has been created. */
void sqlite3PcacheSetPageSize(PCache *, int);
/* Return the size in bytes of a PCache object. Used to preallocate
** storage space.
*/
int sqlite3PcacheSize(void);
/* One release per successful fetch. Page is pinned until released.
** Reference counted.
*/
int sqlite3PcacheFetch(PCache*, Pgno, int createFlag, PgHdr**);
void sqlite3PcacheRelease(PgHdr*);
void sqlite3PcacheDrop(PgHdr*); /* Remove page from cache */
void sqlite3PcacheMakeDirty(PgHdr*); /* Make sure page is marked dirty */
void sqlite3PcacheMakeClean(PgHdr*); /* Mark a single page as clean */
void sqlite3PcacheCleanAll(PCache*); /* Mark all dirty list pages as clean */
/* Change a page number. Used by incr-vacuum. */
void sqlite3PcacheMove(PgHdr*, Pgno);
/* Remove all pages with pgno>x. Reset the cache if x==0 */
void sqlite3PcacheTruncate(PCache*, Pgno x);
/* Get a list of all dirty pages in the cache, sorted by page number */
PgHdr *sqlite3PcacheDirtyList(PCache*);
/* Reset and close the cache object */
void sqlite3PcacheClose(PCache*);
/* Clear flags from pages of the page cache */
void sqlite3PcacheClearSyncFlags(PCache *);
/* Discard the contents of the cache */
void sqlite3PcacheClear(PCache*);
/* Return the total number of outstanding page references */
int sqlite3PcacheRefCount(PCache*);
/* Increment the reference count of an existing page */
void sqlite3PcacheRef(PgHdr*);
int sqlite3PcachePageRefcount(PgHdr*);
/* Return the total number of pages stored in the cache */
int sqlite3PcachePagecount(PCache*);
#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
/* Iterate through all dirty pages currently stored in the cache. This
** interface is only available if SQLITE_CHECK_PAGES is defined when the
** library is built.
*/
void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *));
#endif
/* Set and get the suggested cache-size for the specified pager-cache.
**
** If no global maximum is configured, then the system attempts to limit
** the total number of pages cached by purgeable pager-caches to the sum
** of the suggested cache-sizes.
*/
void sqlite3PcacheSetCachesize(PCache *, int);
#ifdef SQLITE_TEST
int sqlite3PcacheGetCachesize(PCache *);
#endif
/* Free up as much memory as possible from the page cache */
void sqlite3PcacheShrink(PCache*);
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
/* Try to return memory used by the pcache module to the main memory heap */
int sqlite3PcacheReleaseMemory(int);
#endif
#ifdef SQLITE_TEST
void sqlite3PcacheStats(int*,int*,int*,int*);
#endif
void sqlite3PCacheSetDefault(void);
#endif /* _PCACHE_H_ */