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 _TEST_MULTIPLEX_H
  24 #define _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 /*
  50 ** CAPI: Initialize the multiplex VFS shim - sqlite3_multiplex_initialize()
  51 **
  52 ** Use the VFS named zOrigVfsName as the VFS that does the actual work.
  53 ** Use the default if zOrigVfsName==NULL.
  54 **
  55 ** The multiplex VFS shim is named "multiplex".  It will become the default
  56 ** VFS if makeDefault is non-zero.
  57 **
  58 ** An auto-extension is registered which will make the function
  59 ** multiplex_control() available to database connections.  This
  60 ** function gives access to the xFileControl interface of the
  61 ** multiplex VFS shim.
  62 **
  63 ** SELECT multiplex_control(<op>,<val>);
  64 **
  65 **   <op>=1 MULTIPLEX_CTRL_ENABLE
  66 **   <val>=0 disable
  67 **   <val>=1 enable
  68 **
  69 **   <op>=2 MULTIPLEX_CTRL_SET_CHUNK_SIZE
  70 **   <val> int, chunk size
  71 **
  72 **   <op>=3 MULTIPLEX_CTRL_SET_MAX_CHUNKS
  73 **   <val> int, max chunks
  74 **
  75 ** THIS ROUTINE IS NOT THREADSAFE.  Call this routine exactly once
  76 ** during start-up.
  77 */
  78 extern int sqlite3_multiplex_initialize(const char *zOrigVfsName, int makeDefault);
  79
  80 /*
  81 ** CAPI: Shutdown the multiplex system - sqlite3_multiplex_shutdown()
  82 **
  83 ** All SQLite database connections must be closed before calling this
  84 ** routine.
  85 **
  86 ** THIS ROUTINE IS NOT THREADSAFE.  Call this routine exactly once while
  87 ** shutting down in order to free all remaining multiplex groups.
  88 */
  89 extern int sqlite3_multiplex_shutdown(void);
  90
  91 #endif