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sqlcipher/ext/misc/vfsstat.c

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/*
** 2016-05-27
**
** 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 the implementation of an SQLite vfs shim that
** tracks I/O. Access to the accumulated status counts is provided using
** an eponymous virtual table.
*/
#include <sqlite3ext.h>
SQLITE_EXTENSION_INIT1
/*
** This module contains code for a wrapper VFS that cause stats for
** most VFS calls to be recorded.
**
** To use this module, first compile it as a loadable extension. See
** https://www.sqlite.org/loadext.html#build for compilations instructions.
**
** After compliing, load this extension, then open database connections to be
** measured. Query usages status using the vfsstat virtual table:
**
** SELECT * FROM vfsstat;
**
** Reset counters using UPDATE statements against vfsstat:
**
** UPDATE vfsstat SET count=0;
**
** EXAMPLE SCRIPT:
**
** .load ./vfsstat
** .open test.db
** DROP TABLE IF EXISTS t1;
** CREATE TABLE t1(x,y);
** INSERT INTO t1 VALUES(123, randomblob(5000));
** CREATE INDEX t1x ON t1(x);
** DROP TABLE t1;
** VACUUM;
** SELECT * FROM vfsstat WHERE count>0;
**
** LIMITATIONS:
**
** This module increments counters without using mutex protection. So if
** two or more threads try to use this module at the same time, race conditions
** may occur which mess up the counts. This is harmless, other than giving
** incorrect statistics.
*/
#include <string.h>
#include <stdlib.h>
#include <assert.h>
/*
** File types
*/
#define VFSSTAT_MAIN 0 /* Main database file */
#define VFSSTAT_JOURNAL 1 /* Rollback journal */
#define VFSSTAT_WAL 2 /* Write-ahead log file */
#define VFSSTAT_MASTERJRNL 3 /* Master journal */
#define VFSSTAT_SUBJRNL 4 /* Subjournal */
#define VFSSTAT_TEMPDB 5 /* TEMP database */
#define VFSSTAT_TEMPJRNL 6 /* Journal for TEMP database */
#define VFSSTAT_TRANSIENT 7 /* Transient database */
#define VFSSTAT_ANY 8 /* Unspecified file type */
#define VFSSTAT_nFile 9 /* This many file types */
/* Names of the file types. These are allowed values for the
** first column of the vfsstat virtual table.
*/
static const char *azFile[] = {
"database", "journal", "wal", "master-journal", "sub-journal",
"temp-database", "temp-journal", "transient-db", "*"
};
/*
** Stat types
*/
#define VFSSTAT_BYTESIN 0 /* Bytes read in */
#define VFSSTAT_BYTESOUT 1 /* Bytes written out */
#define VFSSTAT_READ 2 /* Read requests */
#define VFSSTAT_WRITE 3 /* Write requests */
#define VFSSTAT_SYNC 4 /* Syncs */
#define VFSSTAT_OPEN 5 /* File opens */
#define VFSSTAT_LOCK 6 /* Lock requests */
#define VFSSTAT_ACCESS 0 /* xAccess calls. filetype==ANY only */
#define VFSSTAT_DELETE 1 /* xDelete calls. filetype==ANY only */
#define VFSSTAT_FULLPATH 2 /* xFullPathname calls. ANY only */
#define VFSSTAT_RANDOM 3 /* xRandomness calls. ANY only */
#define VFSSTAT_SLEEP 4 /* xSleep calls. ANY only */
#define VFSSTAT_CURTIME 5 /* xCurrentTime calls. ANY only */
#define VFSSTAT_nStat 7 /* This many stat types */
/* Names for the second column of the vfsstat virtual table for all
** cases except when the first column is "*" or VFSSTAT_ANY. */
static const char *azStat[] = {
"bytes-in", "bytes-out", "read", "write", "sync", "open", "lock",
};
static const char *azStatAny[] = {
"access", "delete", "fullpathname", "randomness", "sleep", "currenttimestamp",
"not-used"
};
/* Total number of counters */
#define VFSSTAT_MXCNT (VFSSTAT_nStat*VFSSTAT_nFile)
/*
** Performance stats are collected in an instance of the following
** global array.
*/
static sqlite3_uint64 aVfsCnt[VFSSTAT_MXCNT];
/*
** Access to a specific counter
*/
#define STATCNT(filetype,stat) (aVfsCnt[(filetype)*VFSSTAT_nStat+(stat)])
/*
** Forward declaration of objects used by this utility
*/
typedef struct VStatVfs VStatVfs;
typedef struct VStatFile VStatFile;
/* An instance of the VFS */
struct VStatVfs {
sqlite3_vfs base; /* VFS methods */
sqlite3_vfs *pVfs; /* Parent VFS */
};
/* An open file */
struct VStatFile {
sqlite3_file base; /* IO methods */
sqlite3_file *pReal; /* Underlying file handle */
unsigned char eFiletype; /* What type of file is this */
};
#define REALVFS(p) (((VStatVfs*)(p))->pVfs)
/*
** Methods for VStatFile
*/
static int vstatClose(sqlite3_file*);
static int vstatRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
static int vstatWrite(sqlite3_file*,const void*,int iAmt, sqlite3_int64 iOfst);
static int vstatTruncate(sqlite3_file*, sqlite3_int64 size);
static int vstatSync(sqlite3_file*, int flags);
static int vstatFileSize(sqlite3_file*, sqlite3_int64 *pSize);
static int vstatLock(sqlite3_file*, int);
static int vstatUnlock(sqlite3_file*, int);
static int vstatCheckReservedLock(sqlite3_file*, int *pResOut);
static int vstatFileControl(sqlite3_file*, int op, void *pArg);
static int vstatSectorSize(sqlite3_file*);
static int vstatDeviceCharacteristics(sqlite3_file*);
static int vstatShmMap(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
static int vstatShmLock(sqlite3_file*, int offset, int n, int flags);
static void vstatShmBarrier(sqlite3_file*);
static int vstatShmUnmap(sqlite3_file*, int deleteFlag);
static int vstatFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
static int vstatUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p);
/*
** Methods for VStatVfs
*/
static int vstatOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *);
static int vstatDelete(sqlite3_vfs*, const char *zName, int syncDir);
static int vstatAccess(sqlite3_vfs*, const char *zName, int flags, int *);
static int vstatFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut);
static void *vstatDlOpen(sqlite3_vfs*, const char *zFilename);
static void vstatDlError(sqlite3_vfs*, int nByte, char *zErrMsg);
static void (*vstatDlSym(sqlite3_vfs *pVfs, void *p, const char*zSym))(void);
static void vstatDlClose(sqlite3_vfs*, void*);
static int vstatRandomness(sqlite3_vfs*, int nByte, char *zOut);
static int vstatSleep(sqlite3_vfs*, int microseconds);
static int vstatCurrentTime(sqlite3_vfs*, double*);
static int vstatGetLastError(sqlite3_vfs*, int, char *);
static int vstatCurrentTimeInt64(sqlite3_vfs*, sqlite3_int64*);
static VStatVfs vstat_vfs = {
{
2, /* iVersion */
0, /* szOsFile (set by register_vstat()) */
1024, /* mxPathname */
0, /* pNext */
"vfslog", /* zName */
0, /* pAppData */
vstatOpen, /* xOpen */
vstatDelete, /* xDelete */
vstatAccess, /* xAccess */
vstatFullPathname, /* xFullPathname */
vstatDlOpen, /* xDlOpen */
vstatDlError, /* xDlError */
vstatDlSym, /* xDlSym */
vstatDlClose, /* xDlClose */
vstatRandomness, /* xRandomness */
vstatSleep, /* xSleep */
vstatCurrentTime, /* xCurrentTime */
vstatGetLastError, /* xGetLastError */
vstatCurrentTimeInt64 /* xCurrentTimeInt64 */
},
0
};
static const sqlite3_io_methods vstat_io_methods = {
3, /* iVersion */
vstatClose, /* xClose */
vstatRead, /* xRead */
vstatWrite, /* xWrite */
vstatTruncate, /* xTruncate */
vstatSync, /* xSync */
vstatFileSize, /* xFileSize */
vstatLock, /* xLock */
vstatUnlock, /* xUnlock */
vstatCheckReservedLock, /* xCheckReservedLock */
vstatFileControl, /* xFileControl */
vstatSectorSize, /* xSectorSize */
vstatDeviceCharacteristics, /* xDeviceCharacteristics */
vstatShmMap, /* xShmMap */
vstatShmLock, /* xShmLock */
vstatShmBarrier, /* xShmBarrier */
vstatShmUnmap, /* xShmUnmap */
vstatFetch, /* xFetch */
vstatUnfetch /* xUnfetch */
};
/*
** Close an vstat-file.
*/
static int vstatClose(sqlite3_file *pFile){
VStatFile *p = (VStatFile *)pFile;
int rc = SQLITE_OK;
if( p->pReal->pMethods ){
rc = p->pReal->pMethods->xClose(p->pReal);
}
return rc;
}
/*
** Read data from an vstat-file.
*/
static int vstatRead(
sqlite3_file *pFile,
void *zBuf,
int iAmt,
sqlite_int64 iOfst
){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xRead(p->pReal, zBuf, iAmt, iOfst);
STATCNT(p->eFiletype,VFSSTAT_READ)++;
if( rc==SQLITE_OK ){
STATCNT(p->eFiletype,VFSSTAT_BYTESIN) += iAmt;
}
return rc;
}
/*
** Write data to an vstat-file.
*/
static int vstatWrite(
sqlite3_file *pFile,
const void *z,
int iAmt,
sqlite_int64 iOfst
){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xWrite(p->pReal, z, iAmt, iOfst);
STATCNT(p->eFiletype,VFSSTAT_WRITE)++;
if( rc==SQLITE_OK ){
STATCNT(p->eFiletype,VFSSTAT_BYTESOUT) += iAmt;
}
return rc;
}
/*
** Truncate an vstat-file.
*/
static int vstatTruncate(sqlite3_file *pFile, sqlite_int64 size){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xTruncate(p->pReal, size);
return rc;
}
/*
** Sync an vstat-file.
*/
static int vstatSync(sqlite3_file *pFile, int flags){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xSync(p->pReal, flags);
STATCNT(p->eFiletype,VFSSTAT_SYNC)++;
return rc;
}
/*
** Return the current file-size of an vstat-file.
*/
static int vstatFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xFileSize(p->pReal, pSize);
return rc;
}
/*
** Lock an vstat-file.
*/
static int vstatLock(sqlite3_file *pFile, int eLock){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xLock(p->pReal, eLock);
STATCNT(p->eFiletype,VFSSTAT_LOCK)++;
return rc;
}
/*
** Unlock an vstat-file.
*/
static int vstatUnlock(sqlite3_file *pFile, int eLock){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xUnlock(p->pReal, eLock);
STATCNT(p->eFiletype,VFSSTAT_LOCK)++;
return rc;
}
/*
** Check if another file-handle holds a RESERVED lock on an vstat-file.
*/
static int vstatCheckReservedLock(sqlite3_file *pFile, int *pResOut){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xCheckReservedLock(p->pReal, pResOut);
STATCNT(p->eFiletype,VFSSTAT_LOCK)++;
return rc;
}
/*
** File control method. For custom operations on an vstat-file.
*/
static int vstatFileControl(sqlite3_file *pFile, int op, void *pArg){
VStatFile *p = (VStatFile *)pFile;
int rc;
rc = p->pReal->pMethods->xFileControl(p->pReal, op, pArg);
if( op==SQLITE_FCNTL_VFSNAME && rc==SQLITE_OK ){
*(char**)pArg = sqlite3_mprintf("vstat/%z", *(char**)pArg);
}
return rc;
}
/*
** Return the sector-size in bytes for an vstat-file.
*/
static int vstatSectorSize(sqlite3_file *pFile){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xSectorSize(p->pReal);
return rc;
}
/*
** Return the device characteristic flags supported by an vstat-file.
*/
static int vstatDeviceCharacteristics(sqlite3_file *pFile){
int rc;
VStatFile *p = (VStatFile *)pFile;
rc = p->pReal->pMethods->xDeviceCharacteristics(p->pReal);
return rc;
}
/* Create a shared memory file mapping */
static int vstatShmMap(
sqlite3_file *pFile,
int iPg,
int pgsz,
int bExtend,
void volatile **pp
){
VStatFile *p = (VStatFile *)pFile;
return p->pReal->pMethods->xShmMap(p->pReal, iPg, pgsz, bExtend, pp);
}
/* Perform locking on a shared-memory segment */
static int vstatShmLock(sqlite3_file *pFile, int offset, int n, int flags){
VStatFile *p = (VStatFile *)pFile;
return p->pReal->pMethods->xShmLock(p->pReal, offset, n, flags);
}
/* Memory barrier operation on shared memory */
static void vstatShmBarrier(sqlite3_file *pFile){
VStatFile *p = (VStatFile *)pFile;
p->pReal->pMethods->xShmBarrier(p->pReal);
}
/* Unmap a shared memory segment */
static int vstatShmUnmap(sqlite3_file *pFile, int deleteFlag){
VStatFile *p = (VStatFile *)pFile;
return p->pReal->pMethods->xShmUnmap(p->pReal, deleteFlag);
}
/* Fetch a page of a memory-mapped file */
static int vstatFetch(
sqlite3_file *pFile,
sqlite3_int64 iOfst,
int iAmt,
void **pp
){
VStatFile *p = (VStatFile *)pFile;
return p->pReal->pMethods->xFetch(p->pReal, iOfst, iAmt, pp);
}
/* Release a memory-mapped page */
static int vstatUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){
VStatFile *p = (VStatFile *)pFile;
return p->pReal->pMethods->xUnfetch(p->pReal, iOfst, pPage);
}
/*
** Open an vstat file handle.
*/
static int vstatOpen(
sqlite3_vfs *pVfs,
const char *zName,
sqlite3_file *pFile,
int flags,
int *pOutFlags
){
int rc;
VStatFile *p = (VStatFile*)pFile;
p->pReal = (sqlite3_file*)&p[1];
rc = REALVFS(pVfs)->xOpen(REALVFS(pVfs), zName, p->pReal, flags, pOutFlags);
if( flags & SQLITE_OPEN_MAIN_DB ){
p->eFiletype = VFSSTAT_MAIN;
}else if( flags & SQLITE_OPEN_MAIN_JOURNAL ){
p->eFiletype = VFSSTAT_JOURNAL;
}else if( flags & SQLITE_OPEN_WAL ){
p->eFiletype = VFSSTAT_WAL;
}else if( flags & SQLITE_OPEN_MASTER_JOURNAL ){
p->eFiletype = VFSSTAT_MASTERJRNL;
}else if( flags & SQLITE_OPEN_SUBJOURNAL ){
p->eFiletype = VFSSTAT_SUBJRNL;
}else if( flags & SQLITE_OPEN_TEMP_DB ){
p->eFiletype = VFSSTAT_TEMPDB;
}else if( flags & SQLITE_OPEN_TEMP_JOURNAL ){
p->eFiletype = VFSSTAT_TEMPJRNL;
}else{
p->eFiletype = VFSSTAT_TRANSIENT;
}
STATCNT(p->eFiletype,VFSSTAT_OPEN)++;
pFile->pMethods = rc ? 0 : &vstat_io_methods;
return rc;
}
/*
** Delete the file located at zPath. If the dirSync argument is true,
** ensure the file-system modifications are synced to disk before
** returning.
*/
static int vstatDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
int rc;
rc = REALVFS(pVfs)->xDelete(REALVFS(pVfs), zPath, dirSync);
STATCNT(VFSSTAT_ANY,VFSSTAT_DELETE)++;
return rc;
}
/*
** Test for access permissions. Return true if the requested permission
** is available, or false otherwise.
*/
static int vstatAccess(
sqlite3_vfs *pVfs,
const char *zPath,
int flags,
int *pResOut
){
int rc;
rc = REALVFS(pVfs)->xAccess(REALVFS(pVfs), zPath, flags, pResOut);
STATCNT(VFSSTAT_ANY,VFSSTAT_ACCESS)++;
return rc;
}
/*
** Populate buffer zOut with the full canonical pathname corresponding
** to the pathname in zPath. zOut is guaranteed to point to a buffer
** of at least (INST_MAX_PATHNAME+1) bytes.
*/
static int vstatFullPathname(
sqlite3_vfs *pVfs,
const char *zPath,
int nOut,
char *zOut
){
STATCNT(VFSSTAT_ANY,VFSSTAT_FULLPATH)++;
return REALVFS(pVfs)->xFullPathname(REALVFS(pVfs), zPath, nOut, zOut);
}
/*
** Open the dynamic library located at zPath and return a handle.
*/
static void *vstatDlOpen(sqlite3_vfs *pVfs, const char *zPath){
return REALVFS(pVfs)->xDlOpen(REALVFS(pVfs), zPath);
}
/*
** Populate the buffer zErrMsg (size nByte bytes) with a human readable
** utf-8 string describing the most recent error encountered associated
** with dynamic libraries.
*/
static void vstatDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){
REALVFS(pVfs)->xDlError(REALVFS(pVfs), nByte, zErrMsg);
}
/*
** Return a pointer to the symbol zSymbol in the dynamic library pHandle.
*/
static void (*vstatDlSym(sqlite3_vfs *pVfs, void *p, const char *zSym))(void){
return REALVFS(pVfs)->xDlSym(REALVFS(pVfs), p, zSym);
}
/*
** Close the dynamic library handle pHandle.
*/
static void vstatDlClose(sqlite3_vfs *pVfs, void *pHandle){
REALVFS(pVfs)->xDlClose(REALVFS(pVfs), pHandle);
}
/*
** Populate the buffer pointed to by zBufOut with nByte bytes of
** random data.
*/
static int vstatRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
STATCNT(VFSSTAT_ANY,VFSSTAT_RANDOM)++;
return REALVFS(pVfs)->xRandomness(REALVFS(pVfs), nByte, zBufOut);
}
/*
** Sleep for nMicro microseconds. Return the number of microseconds
** actually slept.
*/
static int vstatSleep(sqlite3_vfs *pVfs, int nMicro){
STATCNT(VFSSTAT_ANY,VFSSTAT_SLEEP)++;
return REALVFS(pVfs)->xSleep(REALVFS(pVfs), nMicro);
}
/*
** Return the current time as a Julian Day number in *pTimeOut.
*/
static int vstatCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
STATCNT(VFSSTAT_ANY,VFSSTAT_CURTIME)++;
return REALVFS(pVfs)->xCurrentTime(REALVFS(pVfs), pTimeOut);
}
static int vstatGetLastError(sqlite3_vfs *pVfs, int a, char *b){
return REALVFS(pVfs)->xGetLastError(REALVFS(pVfs), a, b);
}
static int vstatCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *p){
STATCNT(VFSSTAT_ANY,VFSSTAT_CURTIME)++;
return REALVFS(pVfs)->xCurrentTimeInt64(REALVFS(pVfs), p);
}
/*
** A virtual table for accessing the stats collected by this VFS shim
*/
static int vstattabConnect(sqlite3*, void*, int, const char*const*,
sqlite3_vtab**,char**);
static int vstattabBestIndex(sqlite3_vtab*,sqlite3_index_info*);
static int vstattabDisconnect(sqlite3_vtab*);
static int vstattabOpen(sqlite3_vtab*, sqlite3_vtab_cursor**);
static int vstattabClose(sqlite3_vtab_cursor*);
static int vstattabFilter(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
int argc, sqlite3_value **argv);
static int vstattabNext(sqlite3_vtab_cursor*);
static int vstattabEof(sqlite3_vtab_cursor*);
static int vstattabColumn(sqlite3_vtab_cursor*,sqlite3_context*,int);
static int vstattabRowid(sqlite3_vtab_cursor*,sqlite3_int64*);
static int vstattabUpdate(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
/* A cursor for the vfsstat virtual table */
typedef struct VfsStatCursor {
sqlite3_vtab_cursor base; /* Base class. Must be first */
int i; /* Pointing to this aVfsCnt[] value */
} VfsStatCursor;
static int vstattabConnect(
sqlite3 *db,
void *pAux,
int argc, const char *const*argv,
sqlite3_vtab **ppVtab,
char **pzErr
){
sqlite3_vtab *pNew;
int rc;
/* Column numbers */
#define VSTAT_COLUMN_FILE 0
#define VSTAT_COLUMN_STAT 1
#define VSTAT_COLUMN_COUNT 2
rc = sqlite3_declare_vtab(db,"CREATE TABLE x(file,stat,count)");
if( rc==SQLITE_OK ){
pNew = *ppVtab = sqlite3_malloc( sizeof(*pNew) );
if( pNew==0 ) return SQLITE_NOMEM;
memset(pNew, 0, sizeof(*pNew));
}
return rc;
}
/*
** This method is the destructor for vstat table object.
*/
static int vstattabDisconnect(sqlite3_vtab *pVtab){
sqlite3_free(pVtab);
return SQLITE_OK;
}
/*
** Constructor for a new vstat table cursor object.
*/
static int vstattabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
VfsStatCursor *pCur;
pCur = sqlite3_malloc( sizeof(*pCur) );
if( pCur==0 ) return SQLITE_NOMEM;
memset(pCur, 0, sizeof(*pCur));
*ppCursor = &pCur->base;
return SQLITE_OK;
}
/*
** Destructor for a VfsStatCursor.
*/
static int vstattabClose(sqlite3_vtab_cursor *cur){
sqlite3_free(cur);
return SQLITE_OK;
}
/*
** Advance a VfsStatCursor to its next row of output.
*/
static int vstattabNext(sqlite3_vtab_cursor *cur){
((VfsStatCursor*)cur)->i++;
return SQLITE_OK;
}
/*
** Return values of columns for the row at which the VfsStatCursor
** is currently pointing.
*/
static int vstattabColumn(
sqlite3_vtab_cursor *cur, /* The cursor */
sqlite3_context *ctx, /* First argument to sqlite3_result_...() */
int i /* Which column to return */
){
VfsStatCursor *pCur = (VfsStatCursor*)cur;
switch( i ){
case VSTAT_COLUMN_FILE: {
sqlite3_result_text(ctx, azFile[pCur->i/VFSSTAT_nStat], -1, SQLITE_STATIC);
break;
}
case VSTAT_COLUMN_STAT: {
const char **az;
az = (pCur->i/VFSSTAT_nStat)==VFSSTAT_ANY ? azStatAny : azStat;
sqlite3_result_text(ctx, az[pCur->i%VFSSTAT_nStat], -1, SQLITE_STATIC);
break;
}
case VSTAT_COLUMN_COUNT: {
sqlite3_result_int64(ctx, aVfsCnt[pCur->i]);
break;
}
}
return SQLITE_OK;
}
/*
** Return the rowid for the current row.
*/
static int vstattabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
VfsStatCursor *pCur = (VfsStatCursor*)cur;
*pRowid = pCur->i;
return SQLITE_OK;
}
/*
** Return TRUE if the cursor has been moved off of the last
** row of output.
*/
static int vstattabEof(sqlite3_vtab_cursor *cur){
VfsStatCursor *pCur = (VfsStatCursor*)cur;
return pCur->i >= VFSSTAT_MXCNT;
}
/*
** Only a full table scan is supported. So xFilter simply rewinds to
** the beginning.
*/
static int vstattabFilter(
sqlite3_vtab_cursor *pVtabCursor,
int idxNum, const char *idxStr,
int argc, sqlite3_value **argv
){
VfsStatCursor *pCur = (VfsStatCursor*)pVtabCursor;
pCur->i = 0;
return SQLITE_OK;
}
/*
** Only a forwards full table scan is supported. xBestIndex is a no-op.
*/
static int vstattabBestIndex(
sqlite3_vtab *tab,
sqlite3_index_info *pIdxInfo
){
return SQLITE_OK;
}
/*
** Any VSTAT_COLUMN_COUNT can be changed to a positive integer.
** No deletions or insertions are allowed. No changes to other
** columns are allowed.
*/
static int vstattabUpdate(
sqlite3_vtab *tab,
int argc, sqlite3_value **argv,
sqlite3_int64 *pRowid
){
sqlite3_int64 iRowid, x;
if( argc==1 ) return SQLITE_ERROR;
if( sqlite3_value_type(argv[0])!=SQLITE_INTEGER ) return SQLITE_ERROR;
iRowid = sqlite3_value_int64(argv[0]);
if( iRowid!=sqlite3_value_int64(argv[1]) ) return SQLITE_ERROR;
if( iRowid<0 || iRowid>=VFSSTAT_MXCNT ) return SQLITE_ERROR;
if( sqlite3_value_type(argv[VSTAT_COLUMN_COUNT+2])!=SQLITE_INTEGER ){
return SQLITE_ERROR;
}
x = sqlite3_value_int64(argv[VSTAT_COLUMN_COUNT+2]);
if( x<0 ) return SQLITE_ERROR;
aVfsCnt[iRowid] = x;
return SQLITE_OK;
}
static sqlite3_module VfsStatModule = {
0, /* iVersion */
0, /* xCreate */
vstattabConnect, /* xConnect */
vstattabBestIndex, /* xBestIndex */
vstattabDisconnect, /* xDisconnect */
0, /* xDestroy */
vstattabOpen, /* xOpen - open a cursor */
vstattabClose, /* xClose - close a cursor */
vstattabFilter, /* xFilter - configure scan constraints */
vstattabNext, /* xNext - advance a cursor */
vstattabEof, /* xEof - check for end of scan */
vstattabColumn, /* xColumn - read data */
vstattabRowid, /* xRowid - read data */
vstattabUpdate, /* xUpdate */
0, /* xBegin */
0, /* xSync */
0, /* xCommit */
0, /* xRollback */
0, /* xFindMethod */
0, /* xRename */
};
/*
** This routine is an sqlite3_auto_extension() callback, invoked to register
** the vfsstat virtual table for all new database connections.
*/
static int vstatRegister(
sqlite3 *db,
char **pzErrMsg,
const sqlite3_api_routines *pThunk
){
return sqlite3_create_module(db, "vfsstat", &VfsStatModule, 0);
}
#ifdef _WIN32
__declspec(dllexport)
#endif
/*
** This routine is called when the extension is loaded.
**
** Register the new VFS. Make arrangement to register the virtual table
** for each new database connection.
*/
int sqlite3_vfsstat_init(
sqlite3 *db,
char **pzErrMsg,
const sqlite3_api_routines *pApi
){
int rc = SQLITE_OK;
SQLITE_EXTENSION_INIT2(pApi);
vstat_vfs.pVfs = sqlite3_vfs_find(0);
if( vstat_vfs.pVfs==0 ) return SQLITE_ERROR;
vstat_vfs.base.szOsFile = sizeof(VStatFile) + vstat_vfs.pVfs->szOsFile;
rc = sqlite3_vfs_register(&vstat_vfs.base, 1);
if( rc==SQLITE_OK ){
rc = vstatRegister(db, pzErrMsg, pApi);
if( rc==SQLITE_OK ){
rc = sqlite3_auto_extension((void(*)(void))vstatRegister);
}
}
if( rc==SQLITE_OK ) rc = SQLITE_OK_LOAD_PERMANENTLY;
return rc;
}
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