/*
** 2010 October 28
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains a VFS "shim" - a layer that sits in between the
** pager and the real VFS - that breaks up a very large database file
** into two or more smaller files on disk. This is useful, for example,
** in order to support large, multi-gigabyte databases on older filesystems
** that limit the maximum file size to 2 GiB.
**
** USAGE:
**
** Compile this source file and link it with your application. Then
** at start-time, invoke the following procedure:
**
** int sqlite3_multiplex_initialize(
** const char *zOrigVfsName, // The underlying real VFS
** int makeDefault // True to make multiplex the default VFS
** );
**
** The procedure call above will create and register a new VFS shim named
** "multiplex". The multiplex VFS will use the VFS named by zOrigVfsName to
** do the actual disk I/O. (The zOrigVfsName parameter may be NULL, in
** which case the default VFS at the moment sqlite3_multiplex_initialize()
** is called will be used as the underlying real VFS.)
**
** If the makeDefault parameter is TRUE then multiplex becomes the new
** default VFS. Otherwise, you can use the multiplex VFS by specifying
** "multiplex" as the 4th parameter to sqlite3_open_v2() or by employing
** URI filenames and adding "vfs=multiplex" as a parameter to the filename
** URI.
**
** The multiplex VFS allows databases up to 32 GiB in size. But it splits
** the files up into smaller pieces, so that they will work even on
** filesystems that do not support large files. The default chunk size
** is 2147418112 bytes (which is 64KiB less than 2GiB) but this can be
** changed at compile-time by defining the SQLITE_MULTIPLEX_CHUNK_SIZE
** macro. Use the "chunksize=NNNN" query parameter with a URI filename
** in order to select an alternative chunk size for individual connections
** at run-time.
*/
#include "sqlite3.h"
#include <string.h>
#include <assert.h>
#include <stdlib.h>
#include "test_multiplex.h"
#ifndef SQLITE_CORE
#define SQLITE_CORE 1 /* Disable the API redefinition in sqlite3ext.h */
#endif
#include "sqlite3ext.h"
/*
** These should be defined to be the same as the values in
** sqliteInt.h. They are defined seperately here so that
** the multiplex VFS shim can be built as a loadable
** module.
*/
#define UNUSED_PARAMETER(x) (void)(x)
#define MAX_PAGE_SIZE 0x10000
#define DEFAULT_SECTOR_SIZE 0x1000
/*
** For a build without mutexes, no-op the mutex calls.
*/
#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE==0
#define sqlite3_mutex_alloc(X) ((sqlite3_mutex*)8)
#define sqlite3_mutex_free(X)
#define sqlite3_mutex_enter(X)
#define sqlite3_mutex_try(X) SQLITE_OK
#define sqlite3_mutex_leave(X)
#define sqlite3_mutex_held(X) ((void)(X),1)
#define sqlite3_mutex_notheld(X) ((void)(X),1)
#endif /* SQLITE_THREADSAFE==0 */
/************************ Shim Definitions ******************************/
#ifndef SQLITE_MULTIPLEX_VFS_NAME
# define SQLITE_MULTIPLEX_VFS_NAME "multiplex"
#endif
/* This is the limit on the chunk size. It may be changed by calling
** the xFileControl() interface. It will be rounded up to a
** multiple of MAX_PAGE_SIZE. We default it here to 2GiB less 64KiB.
*/
#ifndef SQLITE_MULTIPLEX_CHUNK_SIZE
# define SQLITE_MULTIPLEX_CHUNK_SIZE 2147418112
#endif
/* Default limit on number of chunks. Care should be taken
** so that values for chunks numbers fit in the SQLITE_MULTIPLEX_EXT_FMT
** format specifier. It may be changed by calling
** the xFileControl() interface.
*/
#ifndef SQLITE_MULTIPLEX_MAX_CHUNKS
# define SQLITE_MULTIPLEX_MAX_CHUNKS 32
#endif
/* If SQLITE_MULTIPLEX_EXT_OVWR is defined, the
** last SQLITE_MULTIPLEX_EXT_SZ characters of the
** filename will be overwritten, otherwise, the
** multiplex extension is simply appended to the filename.
** Ex. (undefined) test.db -> test.db01
** (defined) test.db -> test.01
** Chunk 0 does not have a modified extension.
*/
#define SQLITE_MULTIPLEX_EXT_FMT "%02d"
#define SQLITE_MULTIPLEX_EXT_SZ 2
/************************ Object Definitions ******************************/
/* Forward declaration of all object types */
typedef struct multiplexGroup multiplexGroup;
typedef struct multiplexConn multiplexConn;
/*
** A "multiplex group" is a collection of files that collectively
** makeup a single SQLite DB file. This allows the size of the DB
** to exceed the limits imposed by the file system.
**
** There is an instance of the following object for each defined multiplex
** group.
*/
struct multiplexGroup {
struct multiplexReal { /* For each chunk */
sqlite3_file *p; /* Handle for the chunk */
char *z; /* Name of this chunk */
} *aReal; /* list of all chunks */
int nReal; /* Number of chunks */
char *zName; /* Base filename of this group */
int nName; /* Length of base filename */
int flags; /* Flags used for original opening */
unsigned int szChunk; /* Chunk size used for this group */
int bEnabled; /* TRUE to use Multiplex VFS for this file */
multiplexGroup *pNext, *pPrev; /* Doubly linked list of all group objects */
};
/*
** An instance of the following object represents each open connection
** to a file that is multiplex'ed. This object is a
** subclass of sqlite3_file. The sqlite3_file object for the underlying
** VFS is appended to this structure.
*/
struct multiplexConn {
sqlite3_file base; /* Base class - must be first */
multiplexGroup *pGroup; /* The underlying group of files */
};
/************************* Global Variables **********************************/
/*
** All global variables used by this file are containing within the following
** gMultiplex structure.
*/
static struct {
/* The pOrigVfs is the real, original underlying VFS implementation.
** Most operations pass-through to the real VFS. This value is read-only
** during operation. It is only modified at start-time and thus does not
** require a mutex.
*/
sqlite3_vfs *pOrigVfs;
/* The sThisVfs is the VFS structure used by this shim. It is initialized
** at start-time and thus does not require a mutex
*/
sqlite3_vfs sThisVfs;
/* The sIoMethods defines the methods used by sqlite3_file objects
** associated with this shim. It is initialized at start-time and does
** not require a mutex.
**
** When the underlying VFS is called to open a file, it might return
** either a version 1 or a version 2 sqlite3_file object. This shim
** has to create a wrapper sqlite3_file of the same version. Hence
** there are two I/O method structures, one for version 1 and the other
** for version 2.
*/
sqlite3_io_methods sIoMethodsV1;
sqlite3_io_methods sIoMethodsV2;
/* True when this shim has been initialized.
*/
int isInitialized;
/* For run-time access any of the other global data structures in this
** shim, the following mutex must be held.
*/
sqlite3_mutex *pMutex;
/* List of multiplexGroup objects.
*/
multiplexGroup *pGroups;
} gMultiplex;
/************************* Utility Routines *********************************/
/*
** Acquire and release the mutex used to serialize access to the
** list of multiplexGroups.
*/
static void multiplexEnter(void){ sqlite3_mutex_enter(gMultiplex.pMutex); }
static void multiplexLeave(void){ sqlite3_mutex_leave(gMultiplex.pMutex); }
/*
** Compute a string length that is limited to what can be stored in
** lower 30 bits of a 32-bit signed integer.
**
** The value returned will never be negative. Nor will it ever be greater
** than the actual length of the string. For very long strings (greater
** than 1GiB) the value returned might be less than the true string length.
*/
static int multiplexStrlen30(const char *z){
const char *z2 = z;
if( z==0 ) return 0;
while( *z2 ){ z2++; }
return 0x3fffffff & (int)(z2 - z);
}
/*
** Create a temporary file name in zBuf. zBuf must be big enough to
** hold at pOrigVfs->mxPathname characters. This function departs
** from the traditional temporary name generation in the os_win
** and os_unix VFS in several ways, but is necessary so that
** the file name is known for temporary files (like those used
** during vacuum.)
**
** N.B. This routine assumes your underlying VFS is ok with using
** "/" as a directory seperator. This is the default for UNIXs
** and is allowed (even mixed) for most versions of Windows.
*/
static int multiplexGetTempname(sqlite3_vfs *pOrigVfs, int nBuf, char *zBuf){
static char zChars[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789";
int i,j;
int attempts = 0;
int exists = 0;
int rc = SQLITE_ERROR;
/* Check that the output buffer is large enough for
** pVfs->mxPathname characters.
*/
if( pOrigVfs->mxPathname <= nBuf ){
char *zTmp = sqlite3_malloc(pOrigVfs->mxPathname);
if( zTmp==0 ) return SQLITE_NOMEM;
/* sqlite3_temp_directory should always be less than
** pVfs->mxPathname characters.
*/
sqlite3_snprintf(pOrigVfs->mxPathname,
zTmp,
"%s/",
sqlite3_temp_directory ? sqlite3_temp_directory : ".");
rc = pOrigVfs->xFullPathname(pOrigVfs, zTmp, nBuf, zBuf);
sqlite3_free(zTmp);
if( rc ) return rc;
/* Check that the output buffer is large enough for the temporary file
** name.
*/
j = multiplexStrlen30(zBuf);
if( (j + 8 + 1 + 3 + 1) <= nBuf ){
/* Make 3 attempts to generate a unique name. */
do {
attempts++;
sqlite3_randomness(8, &zBuf[j]);
for(i=0; i<8; i++){
unsigned char uc = (unsigned char)zBuf[j+i];
zBuf[j+i] = (char)zChars[uc%(sizeof(zChars)-1)];
}
memcpy(&zBuf[j+i], ".tmp", 5);
rc = pOrigVfs->xAccess(pOrigVfs, zBuf, SQLITE_ACCESS_EXISTS, &exists);
} while ( (rc==SQLITE_OK) && exists && (attempts<3) );
if( rc==SQLITE_OK && exists ){
rc = SQLITE_ERROR;
}
}
}
return rc;
}
/* Compute the filename for the iChunk-th chunk
*/
static int multiplexSubFilename(multiplexGroup *pGroup, int iChunk){
if( iChunk>=pGroup->nReal ){
struct multiplexReal *p;
p = sqlite3_realloc(pGroup->aReal, (iChunk+1)*sizeof(*p));
if( p==0 ){
return SQLITE_NOMEM;
}
memset(&p[pGroup->nReal], 0, sizeof(p[0])*(iChunk+1-pGroup->nReal));
pGroup->aReal = p;
pGroup->nReal = iChunk+1;
}
if( pGroup->aReal[iChunk].z==0 ){
char *z;
int n = pGroup->nName;
pGroup->aReal[iChunk].z = z = sqlite3_malloc( n+3 );
if( z==0 ){
return SQLITE_NOMEM;
}
memcpy(z, pGroup->zName, n+1);
if( iChunk>0 ){
#ifdef SQLITE_ENABLE_8_3_NAMES
if( n>3 && z[n-3]=='.' ){
n--;
}else if( n>4 && z[n-4]=='.' ){
n -= 2;
}
#endif
sqlite3_snprintf(3,&z[n],"%02d",iChunk);
}
}
return SQLITE_OK;
}
/* Translate an sqlite3_file* that is really a multiplexGroup* into
** the sqlite3_file* for the underlying original VFS.
*/
static sqlite3_file *multiplexSubOpen(
multiplexGroup *pGroup,
int iChunk,
int *rc,
int *pOutFlags
){
sqlite3_file *pSubOpen = 0;
sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs; /* Real VFS */
*rc = multiplexSubFilename(pGroup, iChunk);
if( (*rc)==SQLITE_OK && (pSubOpen = pGroup->aReal[iChunk].p)==0 ){
pSubOpen = sqlite3_malloc( pOrigVfs->szOsFile );
if( pSubOpen==0 ){
*rc = SQLITE_NOMEM;
return 0;
}
pGroup->aReal[iChunk].p = pSubOpen;
*rc = pOrigVfs->xOpen(pOrigVfs, pGroup->aReal[iChunk].z, pSubOpen,
pGroup->flags, pOutFlags);
if( *rc!=SQLITE_OK ){
sqlite3_free(pSubOpen);
pGroup->aReal[iChunk].p = 0;
return 0;
}
}
return pSubOpen;
}
/*
** This is the implementation of the multiplex_control() SQL function.
*/
static void multiplexControlFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
int rc = SQLITE_OK;
sqlite3 *db = sqlite3_context_db_handle(context);
int op;
int iVal;
if( !db || argc!=2 ){
rc = SQLITE_ERROR;
}else{
/* extract params */
op = sqlite3_value_int(argv[0]);
iVal = sqlite3_value_int(argv[1]);
/* map function op to file_control op */
switch( op ){
case 1:
op = MULTIPLEX_CTRL_ENABLE;
break;
case 2:
op = MULTIPLEX_CTRL_SET_CHUNK_SIZE;
break;
case 3:
op = MULTIPLEX_CTRL_SET_MAX_CHUNKS;
break;
default:
rc = SQLITE_NOTFOUND;
break;
}
}
if( rc==SQLITE_OK ){
rc = sqlite3_file_control(db, 0, op, &iVal);
}
sqlite3_result_error_code(context, rc);
}
/*
** This is the entry point to register the auto-extension for the
** multiplex_control() function.
*/
static int multiplexFuncInit(
sqlite3 *db,
char **pzErrMsg,
const sqlite3_api_routines *pApi
){
int rc;
rc = sqlite3_create_function(db, "multiplex_control", 2, SQLITE_ANY,
0, multiplexControlFunc, 0, 0);
return rc;
}
/*
** Close a single sub-file in the connection group.
*/
static void multiplexSubClose(
multiplexGroup *pGroup,
int iChunk,
sqlite3_vfs *pOrigVfs
){
sqlite3_file *pSubOpen = pGroup->aReal[iChunk].p;
if( pSubOpen ){
pSubOpen->pMethods->xClose(pSubOpen);
if( pOrigVfs ) pOrigVfs->xDelete(pOrigVfs, pGroup->aReal[iChunk].z, 0);
sqlite3_free(pGroup->aReal[iChunk].p);
}
sqlite3_free(pGroup->aReal[iChunk].z);
memset(&pGroup->aReal[iChunk], 0, sizeof(pGroup->aReal[iChunk]));
}
/*
** Deallocate memory held by a multiplexGroup
*/
static void multiplexFreeComponents(multiplexGroup *pGroup){
int i;
for(i=0; i<pGroup->nReal; i++){ multiplexSubClose(pGroup, i, 0); }
sqlite3_free(pGroup->aReal);
pGroup->aReal = 0;
pGroup->nReal = 0;
}
/************************* VFS Method Wrappers *****************************/
/*
** This is the xOpen method used for the "multiplex" VFS.
**
** Most of the work is done by the underlying original VFS. This method
** simply links the new file into the appropriate multiplex group if it is a
** file that needs to be tracked.
*/
static int multiplexOpen(
sqlite3_vfs *pVfs, /* The multiplex VFS */
const char *zName, /* Name of file to be opened */
sqlite3_file *pConn, /* Fill in this file descriptor */
int flags, /* Flags to control the opening */
int *pOutFlags /* Flags showing results of opening */
){
int rc = SQLITE_OK; /* Result code */
multiplexConn *pMultiplexOpen; /* The new multiplex file descriptor */
multiplexGroup *pGroup; /* Corresponding multiplexGroup object */
sqlite3_file *pSubOpen = 0; /* Real file descriptor */
sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs; /* Real VFS */
int nName;
int sz;
char *zToFree = 0;
UNUSED_PARAMETER(pVfs);
memset(pConn, 0, pVfs->szOsFile);
/* We need to create a group structure and manage
** access to this group of files.
*/
multiplexEnter();
pMultiplexOpen = (multiplexConn*)pConn;
/* If the second argument to this function is NULL, generate a
** temporary file name to use. This will be handled by the
** original xOpen method. We just need to allocate space for
** it.
*/
if( !zName ){
zName = zToFree = sqlite3_malloc( pOrigVfs->mxPathname + 10 );
if( zName==0 ){
rc = SQLITE_NOMEM;
}else{
rc = multiplexGetTempname(pOrigVfs, pOrigVfs->mxPathname, zToFree);
}
}
if( rc==SQLITE_OK ){
/* allocate space for group */
nName = multiplexStrlen30(zName);
sz = sizeof(multiplexGroup) /* multiplexGroup */
+ nName + 1; /* zName */
pGroup = sqlite3_malloc( sz );
if( pGroup==0 ){
rc = SQLITE_NOMEM;
}
}
if( rc==SQLITE_OK ){
/* assign pointers to extra space allocated */
char *p = (char *)&pGroup[1];
pMultiplexOpen->pGroup = pGroup;
memset(pGroup, 0, sz);
pGroup->bEnabled = -1;
pGroup->szChunk = SQLITE_MULTIPLEX_CHUNK_SIZE;
if( flags & SQLITE_OPEN_URI ){
const char *zChunkSize;
zChunkSize = sqlite3_uri_parameter(zName, "chunksize");
if( zChunkSize ){
unsigned int n = 0;
int i;
for(i=0; zChunkSize[i]>='0' && zChunkSize[i]<='9'; i++){
n = n*10 + zChunkSize[i] - '0';
}
if( n>0 ){
pGroup->szChunk = (n+0xffff)&~0xffff;
}else{
/* A zero or negative chunksize disabled the multiplexor */
pGroup->bEnabled = 0;
}
}
}
pGroup->zName = p;
/* save off base filename, name length, and original open flags */
memcpy(pGroup->zName, zName, nName+1);
pGroup->nName = nName;
pGroup->flags = flags;
rc = multiplexSubFilename(pGroup, 1);
if( rc==SQLITE_OK ){
pSubOpen = multiplexSubOpen(pGroup, 0, &rc, pOutFlags);
}
if( pSubOpen ){
int exists, rc2, rc3;
sqlite3_int64 sz;
rc2 = pSubOpen->pMethods->xFileSize(pSubOpen, &sz);
if( rc2==SQLITE_OK ){
/* If the first overflow file exists and if the size of the main file
** is different from the chunk size, that means the chunk size is set
** set incorrectly. So fix it.
**
** Or, if the first overflow file does not exist and the main file is
** larger than the chunk size, that means the chunk size is too small.
** But we have no way of determining the intended chunk size, so
** just disable the multiplexor all togethre.
*/
rc3 = pOrigVfs->xAccess(pOrigVfs, pGroup->aReal[1].z,
SQLITE_ACCESS_EXISTS, &exists);
if( rc3==SQLITE_OK && exists && sz==(sz&0xffff0000) && sz>0
&& sz!=pGroup->szChunk ){
pGroup->szChunk = sz;
}else if( rc3==SQLITE_OK && !exists && sz>pGroup->szChunk ){
pGroup->bEnabled = 0;
}
}
if( pSubOpen->pMethods->iVersion==1 ){
pMultiplexOpen->base.pMethods = &gMultiplex.sIoMethodsV1;
}else{
pMultiplexOpen->base.pMethods = &gMultiplex.sIoMethodsV2;
}
/* place this group at the head of our list */
pGroup->pNext = gMultiplex.pGroups;
if( gMultiplex.pGroups ) gMultiplex.pGroups->pPrev = pGroup;
gMultiplex.pGroups = pGroup;
}else{
multiplexFreeComponents(pGroup);
sqlite3_free(pGroup);
}
}
multiplexLeave();
sqlite3_free(zToFree);
return rc;
}
/*
** This is the xDelete method used for the "multiplex" VFS.
** It attempts to delete the filename specified.
*/
static int multiplexDelete(
sqlite3_vfs *pVfs, /* The multiplex VFS */
const char *zName, /* Name of file to delete */
int syncDir
){
sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs; /* Real VFS */
return pOrigVfs->xDelete(pOrigVfs, zName, syncDir);
}
static int multiplexAccess(sqlite3_vfs *a, const char *b, int c, int *d){
return gMultiplex.pOrigVfs->xAccess(gMultiplex.pOrigVfs, b, c, d);
}
static int multiplexFullPathname(sqlite3_vfs *a, const char *b, int c, char *d){
return gMultiplex.pOrigVfs->xFullPathname(gMultiplex.pOrigVfs, b, c, d);
}
static void *multiplexDlOpen(sqlite3_vfs *a, const char *b){
return gMultiplex.pOrigVfs->xDlOpen(gMultiplex.pOrigVfs, b);
}
static void multiplexDlError(sqlite3_vfs *a, int b, char *c){
gMultiplex.pOrigVfs->xDlError(gMultiplex.pOrigVfs, b, c);
}
static void (*multiplexDlSym(sqlite3_vfs *a, void *b, const char *c))(void){
return gMultiplex.pOrigVfs->xDlSym(gMultiplex.pOrigVfs, b, c);
}
static void multiplexDlClose(sqlite3_vfs *a, void *b){
gMultiplex.pOrigVfs->xDlClose(gMultiplex.pOrigVfs, b);
}
static int multiplexRandomness(sqlite3_vfs *a, int b, char *c){
return gMultiplex.pOrigVfs->xRandomness(gMultiplex.pOrigVfs, b, c);
}
static int multiplexSleep(sqlite3_vfs *a, int b){
return gMultiplex.pOrigVfs->xSleep(gMultiplex.pOrigVfs, b);
}
static int multiplexCurrentTime(sqlite3_vfs *a, double *b){
return gMultiplex.pOrigVfs->xCurrentTime(gMultiplex.pOrigVfs, b);
}
static int multiplexGetLastError(sqlite3_vfs *a, int b, char *c){
return gMultiplex.pOrigVfs->xGetLastError(gMultiplex.pOrigVfs, b, c);
}
static int multiplexCurrentTimeInt64(sqlite3_vfs *a, sqlite3_int64 *b){
return gMultiplex.pOrigVfs->xCurrentTimeInt64(gMultiplex.pOrigVfs, b);
}
/************************ I/O Method Wrappers *******************************/
/* xClose requests get passed through to the original VFS.
** We loop over all open chunk handles and close them.
** The group structure for this file is unlinked from
** our list of groups and freed.
*/
static int multiplexClose(sqlite3_file *pConn){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_OK;
multiplexEnter();
multiplexFreeComponents(pGroup);
/* remove from linked list */
if( pGroup->pNext ) pGroup->pNext->pPrev = pGroup->pPrev;
if( pGroup->pPrev ){
pGroup->pPrev->pNext = pGroup->pNext;
}else{
gMultiplex.pGroups = pGroup->pNext;
}
sqlite3_free(pGroup);
multiplexLeave();
return rc;
}
/* Pass xRead requests thru to the original VFS after
** determining the correct chunk to operate on.
** Break up reads across chunk boundaries.
*/
static int multiplexRead(
sqlite3_file *pConn,
void *pBuf,
int iAmt,
sqlite3_int64 iOfst
){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_OK;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_READ;
}else{
rc = pSubOpen->pMethods->xRead(pSubOpen, pBuf, iAmt, iOfst);
}
}else{
while( iAmt > 0 ){
int i = (int)(iOfst / pGroup->szChunk);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL);
if( pSubOpen ){
int extra = ((int)(iOfst % pGroup->szChunk) + iAmt) - pGroup->szChunk;
if( extra<0 ) extra = 0;
iAmt -= extra;
rc = pSubOpen->pMethods->xRead(pSubOpen, pBuf, iAmt,
iOfst % pGroup->szChunk);
if( rc!=SQLITE_OK ) break;
pBuf = (char *)pBuf + iAmt;
iOfst += iAmt;
iAmt = extra;
}else{
rc = SQLITE_IOERR_READ;
break;
}
}
}
multiplexLeave();
return rc;
}
/* Pass xWrite requests thru to the original VFS after
** determining the correct chunk to operate on.
** Break up writes across chunk boundaries.
*/
static int multiplexWrite(
sqlite3_file *pConn,
const void *pBuf,
int iAmt,
sqlite3_int64 iOfst
){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_OK;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_WRITE;
}else{
rc = pSubOpen->pMethods->xWrite(pSubOpen, pBuf, iAmt, iOfst);
}
}else{
while( iAmt > 0 ){
int i = (int)(iOfst / pGroup->szChunk);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL);
if( pSubOpen ){
int extra = ((int)(iOfst % pGroup->szChunk) + iAmt) -
pGroup->szChunk;
if( extra<0 ) extra = 0;
iAmt -= extra;
rc = pSubOpen->pMethods->xWrite(pSubOpen, pBuf, iAmt,
iOfst % pGroup->szChunk);
if( rc!=SQLITE_OK ) break;
pBuf = (char *)pBuf + iAmt;
iOfst += iAmt;
iAmt = extra;
}else{
rc = SQLITE_IOERR_WRITE;
break;
}
}
}
multiplexLeave();
return rc;
}
/* Pass xTruncate requests thru to the original VFS after
** determining the correct chunk to operate on. Delete any
** chunks above the truncate mark.
*/
static int multiplexTruncate(sqlite3_file *pConn, sqlite3_int64 size){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_OK;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_TRUNCATE;
}else{
rc = pSubOpen->pMethods->xTruncate(pSubOpen, size);
}
}else{
int rc2;
int i;
sqlite3_file *pSubOpen;
sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs; /* Real VFS */
/* delete the chunks above the truncate limit */
for(i=(int)(size / pGroup->szChunk)+1; i<pGroup->nReal; i++){
multiplexSubClose(pGroup, i, pOrigVfs);
}
pSubOpen = multiplexSubOpen(pGroup, (int)(size/pGroup->szChunk), &rc2,0);
if( pSubOpen ){
rc2 = pSubOpen->pMethods->xTruncate(pSubOpen, size % pGroup->szChunk);
if( rc2!=SQLITE_OK ) rc = rc2;
}else{
rc = SQLITE_IOERR_TRUNCATE;
}
}
multiplexLeave();
return rc;
}
/* Pass xSync requests through to the original VFS without change
*/
static int multiplexSync(sqlite3_file *pConn, int flags){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_OK;
int i;
multiplexEnter();
for(i=0; i<pGroup->nReal; i++){
sqlite3_file *pSubOpen = pGroup->aReal[i].p;
if( pSubOpen ){
int rc2 = pSubOpen->pMethods->xSync(pSubOpen, flags);
if( rc2!=SQLITE_OK ) rc = rc2;
}
}
multiplexLeave();
return rc;
}
/* Pass xFileSize requests through to the original VFS.
** Aggregate the size of all the chunks before returning.
*/
static int multiplexFileSize(sqlite3_file *pConn, sqlite3_int64 *pSize){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_OK;
int rc2;
int i;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_FSTAT;
}else{
rc = pSubOpen->pMethods->xFileSize(pSubOpen, pSize);
}
}else{
sqlite3_vfs *pOrigVfs = gMultiplex.pOrigVfs;
*pSize = 0;
for(i=0; 1; i++){
sqlite3_file *pSubOpen = 0;
int exists = 0;
rc = multiplexSubFilename(pGroup, i);
if( rc ) break;
rc2 = pOrigVfs->xAccess(pOrigVfs, pGroup->aReal[i].z,
SQLITE_ACCESS_EXISTS, &exists);
if( rc2==SQLITE_OK && exists){
/* if it exists, open it */
pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL);
}else{
/* stop at first "gap" */
break;
}
if( pSubOpen ){
sqlite3_int64 sz;
rc2 = pSubOpen->pMethods->xFileSize(pSubOpen, &sz);
if( rc2!=SQLITE_OK ){
rc = rc2;
}else{
if( sz>pGroup->szChunk ){
rc = SQLITE_IOERR_FSTAT;
}
*pSize += sz;
}
}else{
break;
}
}
}
multiplexLeave();
return rc;
}
/* Pass xLock requests through to the original VFS unchanged.
*/
static int multiplexLock(sqlite3_file *pConn, int lock){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
return pSubOpen->pMethods->xLock(pSubOpen, lock);
}
return SQLITE_BUSY;
}
/* Pass xUnlock requests through to the original VFS unchanged.
*/
static int multiplexUnlock(sqlite3_file *pConn, int lock){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
return pSubOpen->pMethods->xUnlock(pSubOpen, lock);
}
return SQLITE_IOERR_UNLOCK;
}
/* Pass xCheckReservedLock requests through to the original VFS unchanged.
*/
static int multiplexCheckReservedLock(sqlite3_file *pConn, int *pResOut){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
return pSubOpen->pMethods->xCheckReservedLock(pSubOpen, pResOut);
}
return SQLITE_IOERR_CHECKRESERVEDLOCK;
}
/* Pass xFileControl requests through to the original VFS unchanged,
** except for any MULTIPLEX_CTRL_* requests here.
*/
static int multiplexFileControl(sqlite3_file *pConn, int op, void *pArg){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_ERROR;
sqlite3_file *pSubOpen;
if( !gMultiplex.isInitialized ) return SQLITE_MISUSE;
switch( op ){
case MULTIPLEX_CTRL_ENABLE:
if( pArg ) {
int bEnabled = *(int *)pArg;
pGroup->bEnabled = bEnabled;
rc = SQLITE_OK;
}
break;
case MULTIPLEX_CTRL_SET_CHUNK_SIZE:
if( pArg ) {
unsigned int szChunk = *(unsigned*)pArg;
if( szChunk<1 ){
rc = SQLITE_MISUSE;
}else{
/* Round up to nearest multiple of MAX_PAGE_SIZE. */
szChunk = (szChunk + (MAX_PAGE_SIZE-1));
szChunk &= ~(MAX_PAGE_SIZE-1);
pGroup->szChunk = szChunk;
rc = SQLITE_OK;
}
}
break;
case MULTIPLEX_CTRL_SET_MAX_CHUNKS:
rc = SQLITE_OK;
break;
case SQLITE_FCNTL_SIZE_HINT:
case SQLITE_FCNTL_CHUNK_SIZE:
/* no-op these */
rc = SQLITE_OK;
break;
default:
pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL);
if( pSubOpen ){
rc = pSubOpen->pMethods->xFileControl(pSubOpen, op, pArg);
}
break;
}
return rc;
}
/* Pass xSectorSize requests through to the original VFS unchanged.
*/
static int multiplexSectorSize(sqlite3_file *pConn){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
return pSubOpen->pMethods->xSectorSize(pSubOpen);
}
return DEFAULT_SECTOR_SIZE;
}
/* Pass xDeviceCharacteristics requests through to the original VFS unchanged.
*/
static int multiplexDeviceCharacteristics(sqlite3_file *pConn){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
return pSubOpen->pMethods->xDeviceCharacteristics(pSubOpen);
}
return 0;
}
/* Pass xShmMap requests through to the original VFS unchanged.
*/
static int multiplexShmMap(
sqlite3_file *pConn, /* Handle open on database file */
int iRegion, /* Region to retrieve */
int szRegion, /* Size of regions */
int bExtend, /* True to extend file if necessary */
void volatile **pp /* OUT: Mapped memory */
){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
return pSubOpen->pMethods->xShmMap(pSubOpen, iRegion, szRegion, bExtend,pp);
}
return SQLITE_IOERR;
}
/* Pass xShmLock requests through to the original VFS unchanged.
*/
static int multiplexShmLock(
sqlite3_file *pConn, /* Database file holding the shared memory */
int ofst, /* First lock to acquire or release */
int n, /* Number of locks to acquire or release */
int flags /* What to do with the lock */
){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
return pSubOpen->pMethods->xShmLock(pSubOpen, ofst, n, flags);
}
return SQLITE_BUSY;
}
/* Pass xShmBarrier requests through to the original VFS unchanged.
*/
static void multiplexShmBarrier(sqlite3_file *pConn){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
pSubOpen->pMethods->xShmBarrier(pSubOpen);
}
}
/* Pass xShmUnmap requests through to the original VFS unchanged.
*/
static int multiplexShmUnmap(sqlite3_file *pConn, int deleteFlag){
multiplexConn *p = (multiplexConn*)pConn;
int rc;
sqlite3_file *pSubOpen = multiplexSubOpen(p->pGroup, 0, &rc, NULL);
if( pSubOpen ){
return pSubOpen->pMethods->xShmUnmap(pSubOpen, deleteFlag);
}
return SQLITE_OK;
}
/************************** Public Interfaces *****************************/
/*
** CAPI: Initialize the multiplex VFS shim - sqlite3_multiplex_initialize()
**
** Use the VFS named zOrigVfsName as the VFS that does the actual work.
** Use the default if zOrigVfsName==NULL.
**
** The multiplex VFS shim is named "multiplex". It will become the default
** VFS if makeDefault is non-zero.
**
** THIS ROUTINE IS NOT THREADSAFE. Call this routine exactly once
** during start-up.
*/
int sqlite3_multiplex_initialize(const char *zOrigVfsName, int makeDefault){
sqlite3_vfs *pOrigVfs;
if( gMultiplex.isInitialized ) return SQLITE_MISUSE;
pOrigVfs = sqlite3_vfs_find(zOrigVfsName);
if( pOrigVfs==0 ) return SQLITE_ERROR;
assert( pOrigVfs!=&gMultiplex.sThisVfs );
gMultiplex.pMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
if( !gMultiplex.pMutex ){
return SQLITE_NOMEM;
}
gMultiplex.pGroups = NULL;
gMultiplex.isInitialized = 1;
gMultiplex.pOrigVfs = pOrigVfs;
gMultiplex.sThisVfs = *pOrigVfs;
gMultiplex.sThisVfs.szOsFile += sizeof(multiplexConn);
gMultiplex.sThisVfs.zName = SQLITE_MULTIPLEX_VFS_NAME;
gMultiplex.sThisVfs.xOpen = multiplexOpen;
gMultiplex.sThisVfs.xDelete = multiplexDelete;
gMultiplex.sThisVfs.xAccess = multiplexAccess;
gMultiplex.sThisVfs.xFullPathname = multiplexFullPathname;
gMultiplex.sThisVfs.xDlOpen = multiplexDlOpen;
gMultiplex.sThisVfs.xDlError = multiplexDlError;
gMultiplex.sThisVfs.xDlSym = multiplexDlSym;
gMultiplex.sThisVfs.xDlClose = multiplexDlClose;
gMultiplex.sThisVfs.xRandomness = multiplexRandomness;
gMultiplex.sThisVfs.xSleep = multiplexSleep;
gMultiplex.sThisVfs.xCurrentTime = multiplexCurrentTime;
gMultiplex.sThisVfs.xGetLastError = multiplexGetLastError;
gMultiplex.sThisVfs.xCurrentTimeInt64 = multiplexCurrentTimeInt64;
gMultiplex.sIoMethodsV1.iVersion = 1;
gMultiplex.sIoMethodsV1.xClose = multiplexClose;
gMultiplex.sIoMethodsV1.xRead = multiplexRead;
gMultiplex.sIoMethodsV1.xWrite = multiplexWrite;
gMultiplex.sIoMethodsV1.xTruncate = multiplexTruncate;
gMultiplex.sIoMethodsV1.xSync = multiplexSync;
gMultiplex.sIoMethodsV1.xFileSize = multiplexFileSize;
gMultiplex.sIoMethodsV1.xLock = multiplexLock;
gMultiplex.sIoMethodsV1.xUnlock = multiplexUnlock;
gMultiplex.sIoMethodsV1.xCheckReservedLock = multiplexCheckReservedLock;
gMultiplex.sIoMethodsV1.xFileControl = multiplexFileControl;
gMultiplex.sIoMethodsV1.xSectorSize = multiplexSectorSize;
gMultiplex.sIoMethodsV1.xDeviceCharacteristics =
multiplexDeviceCharacteristics;
gMultiplex.sIoMethodsV2 = gMultiplex.sIoMethodsV1;
gMultiplex.sIoMethodsV2.iVersion = 2;
gMultiplex.sIoMethodsV2.xShmMap = multiplexShmMap;
gMultiplex.sIoMethodsV2.xShmLock = multiplexShmLock;
gMultiplex.sIoMethodsV2.xShmBarrier = multiplexShmBarrier;
gMultiplex.sIoMethodsV2.xShmUnmap = multiplexShmUnmap;
sqlite3_vfs_register(&gMultiplex.sThisVfs, makeDefault);
sqlite3_auto_extension((void*)multiplexFuncInit);
return SQLITE_OK;
}
/*
** CAPI: Shutdown the multiplex system - sqlite3_multiplex_shutdown()
**
** All SQLite database connections must be closed before calling this
** routine.
**
** THIS ROUTINE IS NOT THREADSAFE. Call this routine exactly once while
** shutting down in order to free all remaining multiplex groups.
*/
int sqlite3_multiplex_shutdown(void){
if( gMultiplex.isInitialized==0 ) return SQLITE_MISUSE;
if( gMultiplex.pGroups ) return SQLITE_MISUSE;
gMultiplex.isInitialized = 0;
sqlite3_mutex_free(gMultiplex.pMutex);
sqlite3_vfs_unregister(&gMultiplex.sThisVfs);
memset(&gMultiplex, 0, sizeof(gMultiplex));
return SQLITE_OK;
}
/***************************** Test Code ***********************************/
#ifdef SQLITE_TEST
#include <tcl.h>
extern const char *sqlite3TestErrorName(int);
/*
** tclcmd: sqlite3_multiplex_initialize NAME MAKEDEFAULT
*/
static int test_multiplex_initialize(
void * clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *CONST objv[]
){
const char *zName; /* Name of new multiplex VFS */
int makeDefault; /* True to make the new VFS the default */
int rc; /* Value returned by multiplex_initialize() */
UNUSED_PARAMETER(clientData);
/* Process arguments */
if( objc!=3 ){
Tcl_WrongNumArgs(interp, 1, objv, "NAME MAKEDEFAULT");
return TCL_ERROR;
}
zName = Tcl_GetString(objv[1]);
if( Tcl_GetBooleanFromObj(interp, objv[2], &makeDefault) ) return TCL_ERROR;
if( zName[0]=='\0' ) zName = 0;
/* Call sqlite3_multiplex_initialize() */
rc = sqlite3_multiplex_initialize(zName, makeDefault);
Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_STATIC);
return TCL_OK;
}
/*
** tclcmd: sqlite3_multiplex_shutdown
*/
static int test_multiplex_shutdown(
void * clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *CONST objv[]
){
int rc; /* Value returned by multiplex_shutdown() */
UNUSED_PARAMETER(clientData);
if( objc!=1 ){
Tcl_WrongNumArgs(interp, 1, objv, "");
return TCL_ERROR;
}
/* Call sqlite3_multiplex_shutdown() */
rc = sqlite3_multiplex_shutdown();
Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_STATIC);
return TCL_OK;
}
/*
** tclcmd: sqlite3_multiplex_dump
*/
static int test_multiplex_dump(
void * clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *CONST objv[]
){
Tcl_Obj *pResult;
Tcl_Obj *pGroupTerm;
multiplexGroup *pGroup;
int i;
int nChunks = 0;
UNUSED_PARAMETER(clientData);
UNUSED_PARAMETER(objc);
UNUSED_PARAMETER(objv);
pResult = Tcl_NewObj();
multiplexEnter();
for(pGroup=gMultiplex.pGroups; pGroup; pGroup=pGroup->pNext){
pGroupTerm = Tcl_NewObj();
pGroup->zName[pGroup->nName] = '\0';
Tcl_ListObjAppendElement(interp, pGroupTerm,
Tcl_NewStringObj(pGroup->zName, -1));
Tcl_ListObjAppendElement(interp, pGroupTerm,
Tcl_NewIntObj(pGroup->nName));
Tcl_ListObjAppendElement(interp, pGroupTerm,
Tcl_NewIntObj(pGroup->flags));
/* count number of chunks with open handles */
for(i=0; i<pGroup->nReal; i++){
if( pGroup->aReal[i].p!=0 ) nChunks++;
}
Tcl_ListObjAppendElement(interp, pGroupTerm,
Tcl_NewIntObj(nChunks));
Tcl_ListObjAppendElement(interp, pGroupTerm,
Tcl_NewIntObj(pGroup->szChunk));
Tcl_ListObjAppendElement(interp, pGroupTerm,
Tcl_NewIntObj(pGroup->nReal));
Tcl_ListObjAppendElement(interp, pResult, pGroupTerm);
}
multiplexLeave();
Tcl_SetObjResult(interp, pResult);
return TCL_OK;
}
/*
** Tclcmd: test_multiplex_control HANDLE DBNAME SUB-COMMAND ?INT-VALUE?
*/
static int test_multiplex_control(
ClientData cd,
Tcl_Interp *interp,
int objc,
Tcl_Obj *CONST objv[]
){
int rc; /* Return code from file_control() */
int idx; /* Index in aSub[] */
Tcl_CmdInfo cmdInfo; /* Command info structure for HANDLE */
sqlite3 *db; /* Underlying db handle for HANDLE */
int iValue = 0;
void *pArg = 0;
struct SubCommand {
const char *zName;
int op;
int argtype;
} aSub[] = {
{ "enable", MULTIPLEX_CTRL_ENABLE, 1 },
{ "chunk_size", MULTIPLEX_CTRL_SET_CHUNK_SIZE, 1 },
{ "max_chunks", MULTIPLEX_CTRL_SET_MAX_CHUNKS, 1 },
{ 0, 0, 0 }
};
if( objc!=5 ){
Tcl_WrongNumArgs(interp, 1, objv, "HANDLE DBNAME SUB-COMMAND INT-VALUE");
return TCL_ERROR;
}
if( 0==Tcl_GetCommandInfo(interp, Tcl_GetString(objv[1]), &cmdInfo) ){
Tcl_AppendResult(interp, "expected database handle, got \"", 0);
Tcl_AppendResult(interp, Tcl_GetString(objv[1]), "\"", 0);
return TCL_ERROR;
}else{
db = *(sqlite3 **)cmdInfo.objClientData;
}
rc = Tcl_GetIndexFromObjStruct(
interp, objv[3], aSub, sizeof(aSub[0]), "sub-command", 0, &idx
);
if( rc!=TCL_OK ) return rc;
switch( aSub[idx].argtype ){
case 1:
if( Tcl_GetIntFromObj(interp, objv[4], &iValue) ){
return TCL_ERROR;
}
pArg = (void *)&iValue;
break;
default:
Tcl_WrongNumArgs(interp, 4, objv, "SUB-COMMAND");
return TCL_ERROR;
}
rc = sqlite3_file_control(db, Tcl_GetString(objv[2]), aSub[idx].op, pArg);
Tcl_SetResult(interp, (char *)sqlite3TestErrorName(rc), TCL_STATIC);
return (rc==SQLITE_OK) ? TCL_OK : TCL_ERROR;
}
/*
** This routine registers the custom TCL commands defined in this
** module. This should be the only procedure visible from outside
** of this module.
*/
int Sqlitemultiplex_Init(Tcl_Interp *interp){
static struct {
char *zName;
Tcl_ObjCmdProc *xProc;
} aCmd[] = {
{ "sqlite3_multiplex_initialize", test_multiplex_initialize },
{ "sqlite3_multiplex_shutdown", test_multiplex_shutdown },
{ "sqlite3_multiplex_dump", test_multiplex_dump },
{ "sqlite3_multiplex_control", test_multiplex_control },
};
int i;
for(i=0; i<sizeof(aCmd)/sizeof(aCmd[0]); i++){
Tcl_CreateObjCommand(interp, aCmd[i].zName, aCmd[i].xProc, 0, 0);
}
return TCL_OK;
}
#endif