src/test_multiplex.h

   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 multiplex 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 */