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