1 /*
2 ** 2011 March 18
3 **
4 ** The author disclaims copyright to this source code.  In place of
5 ** a legal notice, here is a blessing:
6 **
7 **    May you do good and not evil.
8 **    May you find forgiveness for yourself and forgive others.
9 **    May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 **
13 ** This file contains a VFS "shim" - a layer that sits in between the
14 ** pager and the real VFS.
15 **
16 ** This particular shim enforces a multiplex system on DB files.
17 ** This shim shards/partitions a single DB file into smaller
18 ** "chunks" such that the total DB file size may exceed the maximum
19 ** file size of the underlying file system.
20 **
21 */
22 
23 #ifndef SQLITE_TEST_MULTIPLEX_H
24 #define SQLITE_TEST_MULTIPLEX_H
25 
26 /*
27 ** CAPI: File-control Operations Supported by Multiplex VFS
28 **
29 ** Values interpreted by the xFileControl method of a Multiplex VFS db file-handle.
30 **
31 ** MULTIPLEX_CTRL_ENABLE:
32 **   This file control is used to enable or disable the multiplex
33 **   shim.
34 **
35 ** MULTIPLEX_CTRL_SET_CHUNK_SIZE:
36 **   This file control is used to set the maximum allowed chunk
37 **   size for a multiplex file set.  The chunk size should be
38 **   a multiple of SQLITE_MAX_PAGE_SIZE, and will be rounded up
39 **   if not.
40 **
41 ** MULTIPLEX_CTRL_SET_MAX_CHUNKS:
42 **   This file control is used to set the maximum number of chunks
43 **   allowed to be used for a mutliplex file set.
44 */
45 #define MULTIPLEX_CTRL_ENABLE          214014
46 #define MULTIPLEX_CTRL_SET_CHUNK_SIZE  214015
47 #define MULTIPLEX_CTRL_SET_MAX_CHUNKS  214016
48 
49 #ifdef __cplusplus
50 extern "C" {
51 #endif
52 
53 /*
54 ** CAPI: Initialize the multiplex VFS shim - sqlite3_multiplex_initialize()
55 **
56 ** Use the VFS named zOrigVfsName as the VFS that does the actual work.
57 ** Use the default if zOrigVfsName==NULL.
58 **
59 ** The multiplex VFS shim is named "multiplex".  It will become the default
60 ** VFS if makeDefault is non-zero.
61 **
62 ** An auto-extension is registered which will make the function
63 ** multiplex_control() available to database connections.  This
64 ** function gives access to the xFileControl interface of the
65 ** multiplex VFS shim.
66 **
67 ** SELECT multiplex_control(<op>,<val>);
68 **
69 **   <op>=1 MULTIPLEX_CTRL_ENABLE
70 **   <val>=0 disable
71 **   <val>=1 enable
72 **
73 **   <op>=2 MULTIPLEX_CTRL_SET_CHUNK_SIZE
74 **   <val> int, chunk size
75 **
76 **   <op>=3 MULTIPLEX_CTRL_SET_MAX_CHUNKS
77 **   <val> int, max chunks
78 **
79 ** THIS ROUTINE IS NOT THREADSAFE.  Call this routine exactly once
80 ** during start-up.
81 */
82 extern int sqlite3_multiplex_initialize(const char *zOrigVfsName, int makeDefault);
83 
84 /*
85 ** CAPI: Shutdown the multiplex system - sqlite3_multiplex_shutdown()
86 **
87 ** All SQLite database connections must be closed before calling this
88 ** routine.
89 **
90 ** THIS ROUTINE IS NOT THREADSAFE.  Call this routine exactly once while
91 ** shutting down in order to free all remaining multiplex groups.
92 */
93 extern int sqlite3_multiplex_shutdown(int eForce);
94 
95 #ifdef __cplusplus
96 }  /* End of the 'extern "C"' block */
97 #endif
98 
99 #endif /* SQLITE_TEST_MULTIPLEX_H */
100