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      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
     92