SQLite4  Check-in [15856cf080]

};

/* 
** Functions in wrapper2.cc (a C++ source file). wrapper2.cc contains the
** wrapper for Kyoto Cabinet. Kyoto cabinet has a C API, but
** the primary interface is the C++ API.
*/
int test_kc_open(const char*, const char *zFilename, int bClear, TestDb **ppDb);
int test_kc_close(TestDb *);
int test_kc_write(TestDb *, void *, int , void *, int);
int test_kc_delete(TestDb *, void *, int);
int test_kc_delete_range(TestDb *, void *, int, void *, int);
int test_kc_fetch(TestDb *, void *, int, void **, int *);
int test_kc_scan(TestDb *, void *, int, void *, int, void *, int,
  void (*)(void *, void *, int , void *, int)
);

int test_mdb_open(const char*, const char *zFile, int bClear, TestDb **ppDb);
int test_mdb_close(TestDb *);
int test_mdb_write(TestDb *, void *, int , void *, int);
int test_mdb_delete(TestDb *, void *, int);
int test_mdb_fetch(TestDb *, void *, int, void **, int *);
int test_mdb_scan(TestDb *, void *, int, void *, int, void *, int,
  void (*)(void *, void *, int , void *, int)
);

/* 
** Functions in wrapper3.c. This file contains the tdb wrapper for lsm.
** The wrapper for lsm is a bit more involved than the others, as it 
** includes code for a couple of different lsm configurations, and for
** various types of fault injection and robustness testing.
*/
int test_lsm_open(const char*, const char *zFile, int bClear, TestDb **ppDb);
int test_lsm_lomem_open(const char*, const char*, int bClear, TestDb **ppDb);
int test_lsm_zip_open(const char*, const char*, int bClear, TestDb **ppDb);
int test_lsm_small_open(const char*, const char*, int bClear, TestDb **ppDb);
int test_lsm_mt2(const char*, const char *zFile, int bClear, TestDb **ppDb);
int test_lsm_mt3(const char*, const char *zFile, int bClear, TestDb **ppDb);

int tdb_lsm_configure(lsm_db *, const char *);

/* Functions in lsmtest_tdb4.c */
int test_bt_open(const char*, const char *zFilename, int bClear, TestDb **ppDb);


/* Functions in testutil.c. */
int  testPrngInit(void);
u32  testPrngValue(u32 iVal);
void testPrngArray(u32 iVal, u32 *aOut, int nOut);
void testPrngString(u32 iVal, char *aOut, int nOut);

  void **ppKey, int *pnKey,
  void **ppVal, int *pnVal
){
  assert( (ppKey==0)==(pnKey==0) );
  assert( (ppVal==0)==(pnVal==0) );

  if( ppKey ){
    int nKey = 0;
    switch( p->eType ){
      case TEST_DATASOURCE_RANDOM: {
        int nRange = (1 + p->nMaxKey - p->nMinKey);
        nKey = (int)( testPrngValue((u32)iData) % nRange ) + p->nMinKey; 
        testPrngString((u32)iData, p->aKey, nKey);
        break;
      }

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>


void test_failed(){ 
  assert( 0 );
  return; 
}

#define testSetError(rc) testSetErrorFunc(rc, pRc, __FILE__, __LINE__)
static void testSetErrorFunc(int rc, int *pRc, const char *zFile, int iLine){
  if( rc ){
    *pRc = rc;
    printf("FAILED (%s:%d) rc=%d ", zFile, iLine, rc);
    test_failed();

    }
    if( aOpt[iSel].eVal>=0 ){
      aParam[aOpt[iSel].eVal] = atoi(azArg[i+1]);
    }else{
      int j;
      zSystem = azArg[i+1];
      bLsm = 0;
#if 0
      for(j=0; zSystem[j]; j++){
        if( zSystem[j]=='=' ) bLsm = 1;
      }
#endif
    }
  }
  
  printf("#");
  for(i=0; i<ArraySize(aOpt); i++){
    if( aOpt[i].zOpt ){
      if( aOpt[i].eVal>=0 ){

#if 0
  pLog = fopen("/tmp/speed.log", "w");
  tdb_lsm_write_hook(pDb, do_speed_write_hook2, (void *)pLog);
#endif

  for(i=0; i<aParam[ST_REPEAT] && rc==0; i++){
    int msWrite, msFetch;
    int iFetch;
    int nWrite = aParam[ST_WRITE];

    if( bReadonly ){
      msWrite = 0;
    }else{
      testTimeInit();

static int st_do_io(int a, char **b)        { return do_io(a, b); }

#ifdef __linux__
#include <sys/time.h>
#include <sys/resource.h>

static void lsmtest_rusage_report(void){

  struct rusage r;
  memset(&r, 0, sizeof(r));

  getrusage(RUSAGE_SELF, &r);


  printf("# getrusage: { ru_maxrss %d ru_oublock %d ru_inblock %d }\n", 
      (int)r.ru_maxrss, (int)r.ru_oublock, (int)r.ru_inblock
  );
}
#else
static void lsmtest_rusage_report(void){
  /* no-op */

    }
  }

  leveldb_iter_destroy(iter);
  return 0;
}

static int test_leveldb_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  static const DatabaseMethods LeveldbMethods = {
    test_leveldb_close,
    test_leveldb_write,
    test_leveldb_delete,
    0,
    test_leveldb_fetch,
    test_leveldb_scan,

  void (*xCallback)(void *, void *, int , void *, int)
){
  return test_kc_scan(
      pTestDb, pCtx, bReverse, pFirst, nFirst, pLast, nLast, xCallback
  );
}

static int kc_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  static const DatabaseMethods KcdbMethods = {
    kc_close,
    kc_write,
    kc_delete,
    kc_delete_range,
    kc_fetch,
    kc_scan,

  void (*xCallback)(void *, void *, int , void *, int)
){
  return test_mdb_scan(
      pTestDb, pCtx, bReverse, pFirst, nFirst, pLast, nLast, xCallback
  );
}

static int mdb_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  static const DatabaseMethods KcdbMethods = {
    mdb_close,
    mdb_write,
    mdb_delete,
    0,
    mdb_fetch,
    mdb_scan,
    error_transaction_function,
    error_transaction_function,
    error_transaction_function
  };

  int rc;
  TestDb *pTestDb = 0;

  rc = test_mdb_open(zSpec, zFilename, bClear, &pTestDb);
  if( rc!=0 ){
    *ppDb = 0;
    return rc;
  }
  pTestDb->pMethods = &KcdbMethods;
  *ppDb = pTestDb;
  return 0;

    if( rc!=0 ) return rc;
  }

  pDb->nOpenTrans = iLevel;
  return 0;
}

static int sql_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  static const DatabaseMethods SqlMethods = {
    sql_close,
    sql_write,
    sql_delete,
    sql_delete_range,
    sql_fetch,
    sql_scan,

/*************************************************************************
** Begin exported functions.
*/
static struct Lib {
  const char *zName;
  const char *zDefaultDb;
  int (*xOpen)(const char *, const char *zFilename, int bClear, TestDb **ppDb);
} aLib[] = {
  { "bt",           "testdb.bt",        test_bt_open },
  { "sqlite3",      "testdb.sqlite",    sql_open },
  { "lsm_small",    "testdb.lsm_small", test_lsm_small_open },
  { "lsm_lomem",    "testdb.lsm_lomem", test_lsm_lomem_open },
#ifdef HAVE_ZLIB
  { "lsm_zip",      "testdb.lsm_zip",   test_lsm_zip_open },

};

const char *tdb_system_name(int i){
  if( i<0 || i>=ArraySize(aLib) ) return 0;
  return aLib[i].zName;
}

int tdb_open(const char *zLib, const char *zDb, int bClear, TestDb **ppDb){
  int i;
  int rc = 1;
  const char *zSpec = 0;

  int nLib = 0;
  while( zLib[nLib] && zLib[nLib]!=' ' ){
    nLib++;
  }
  zSpec = &zLib[nLib];
  while( *zSpec==' ' ) zSpec++;
  if( *zSpec=='\0' ) zSpec = 0;

  for(i=0; i<ArraySize(aLib); i++){
    if( strlen(aLib[i].zName)==nLib && 0==memcmp(zLib, aLib[i].zName, nLib) ){
      rc = aLib[i].xOpen(zSpec, (zDb ? zDb : aLib[i].zDefaultDb), bClear, ppDb);
      if( rc==0 ){
        (*ppDb)->zLibrary = aLib[i].zName;
      }
      break;
    }
  }

  struct MdbDb {
    TestDb base;
    MDB_env *env;
    MDB_dbi dbi;
  };
}

int test_mdb_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  MDB_txn *txn;
  MdbDb *pMdb;
  int rc;

  if( bClear ){
    char *zCmd = sqlite3_mprintf("rm -rf %s\n", zFilename);
    system(zCmd);

    }
  }

  *ppDb = (TestDb *)pDb;
  return rc;
}

int test_lsm_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  return testLsmOpen("", zFilename, bClear, ppDb);
}

int test_lsm_small_open(
  const char *zSpec, 
  const char *zFile, 
  int bClear, 
  TestDb **ppDb
){
  const char *zCfg = "page_size=256 block_size=64 mmap=1024";
  return testLsmOpen(zCfg, zFile, bClear, ppDb);
}

int test_lsm_lomem_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
    /* "max_freelist=4 autocheckpoint=32" */
  const char *zCfg = 
    "page_size=256 block_size=64 autoflush=16 "
    "autocheckpoint=32"
    "mmap=0 "
  ;
  return testLsmOpen(zCfg, zFilename, bClear, ppDb);
}

int test_lsm_zip_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  const char *zCfg = 
    "page_size=256 block_size=64 autoflush=16 "
    "autocheckpoint=32 compression=1 mmap=0 "

static void *worker_main(void *pArg){
  LsmWorker *p = (LsmWorker *)pArg;
  lsm_db *pWorker;                /* Connection to access db through */

  pthread_mutex_lock(&p->worker_mutex);
  while( (pWorker = p->pWorker) ){
    int rc = LSM_OK;


    /* Do some work. If an error occurs, exit. */

    pthread_mutex_unlock(&p->worker_mutex);
    if( p->eType==LSMTEST_THREAD_CKPT ){
      int nKB = 0;
      rc = lsm_info(pWorker, LSM_INFO_CHECKPOINT_SIZE, &nKB);

      break;
  }

  return rc;
}


int test_lsm_mt2(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  const char *zCfg = "mt_mode=2";
  return testLsmOpen(zCfg, zFilename, bClear, ppDb);
}

int test_lsm_mt3(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
  const char *zCfg = "mt_mode=4";
  return testLsmOpen(zCfg, zFilename, bClear, ppDb);
}

#else
static void mt_shutdown(LsmDb *pDb) { 
  unused_parameter(pDb); 

static int bt_rollback(TestDb *pTestDb, int iLvl){
  BtDb *p = (BtDb*)pTestDb;
  int rc = sqlite4BtRollback(p->pBt, iLvl);
  return rc;
}

static int testParseOption(
  const char **pzIn,              /* IN/OUT: pointer to next option */
  const char **pzOpt,             /* OUT: nul-terminated option name */
  const char **pzArg,             /* OUT: nul-terminated option argument */
  char *pSpace                    /* Temporary space for output params */
){
  const char *p = *pzIn;
  const char *pStart;
  int n;

  char *pOut = pSpace;

  while( *p==' ' ) p++;
  pStart = p;
  while( *p && *p!='=' ) p++;
  if( *p==0 ) return 1;

  n = (p - pStart);
  memcpy(pOut, pStart, n);
  *pzOpt = pOut;
  pOut += n;
  *pOut++ = '\0';

  p++;
  pStart = p;
  while( *p && *p!=' ' ) p++;
  n = (p - pStart);

  memcpy(pOut, pStart, n);
  *pzArg = pOut;
  pOut += n;
  *pOut++ = '\0';

  *pzIn = p;
  return 0;
}

static int testParseInt(const char *z, int *piVal){
  int i = 0;
  const char *p = z;

  while( *p>='0' && *p<='9' ){
    i = i*10 + (*p - '0');
    p++;
  }
  if( *p=='K' || *p=='k' ){
    i = i * 1000;
    p++;
  }else if( *p=='M' || *p=='m' ){
    i = i * 1000000;
    p++;
  }

  if( *p ) return SQLITE4_ERROR;
  *piVal = i;
  return SQLITE4_OK;
}

static int testBtConfigure(bt_db *db, const char *zCfg){
  int rc = SQLITE4_OK;

  if( zCfg ){
    struct CfgParam {
      const char *zParam;
      int eParam;
    } aParam[] = {
      { "safety",         BT_CONTROL_SAFETY },
      { "autockpt",       BT_CONTROL_AUTOCKPT }
    };
    const char *z = zCfg;
    int n = strlen(z);
    char *aSpace;
    const char *zOpt;
    const char *zArg;

    aSpace = (char*)testMalloc(n+2);
    while( 0==testParseOption(&z, &zOpt, &zArg, aSpace) ){
      int i;
      int iVal;
      rc = testArgSelect(aParam, "param", zOpt, &i);
      if( rc!=SQLITE4_OK ) break;

      rc = testParseInt(zArg, &iVal);
      if( rc!=SQLITE4_OK ) break;

      rc = sqlite4BtControl(db, aParam[i].eParam, (void*)&iVal);
      if( rc!=SQLITE4_OK ) break;
    }
    testFree(aSpace);
  }

  return rc;
}


int test_bt_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){

  static const DatabaseMethods SqlMethods = {
    bt_close,
    bt_write,
    bt_delete,
    bt_delete_range,
    bt_fetch,

    p->env.xShmMap = btVfsShmMap;
    p->env.xShmBarrier = btVfsShmBarrier;
    p->env.xShmUnmap = btVfsShmUnmap;

    sqlite4BtControl(pBt, BT_CONTROL_GETVFS, (void*)&p->pVfs);
    sqlite4BtControl(pBt, BT_CONTROL_SETVFS, (void*)&p->env);

    rc = testBtConfigure(pBt, zSpec);
    if( rc==SQLITE4_OK ){
      rc = sqlite4BtOpen(pBt, zFilename);
    }
  }

  if( rc!=SQLITE4_OK && p ){
    bt_close(&p->base);
  }

  *ppDb = &p->base;

**   to the current bt_env object.
**
** BT_CONTROL_SAFETY:
**   The third argument is interpreted as a pointer to type (int). If
**   the value stored in the (int) location is 0, 1 or 2, then the current
**   b-tree safety level is set to 0, 1 or 2, respectively. Otherwise, the
**   integer value is set to the current safety level.
**
** BT_CONTROL_AUTOCKPT:
*/
#define BT_CONTROL_INFO     7706389
#define BT_CONTROL_SETVFS   7706390
#define BT_CONTROL_GETVFS   7706391
#define BT_CONTROL_SAFETY   7706392
#define BT_CONTROL_AUTOCKPT 7706393

int sqlite4BtControl(bt_db*, int op, void *pArg);

#define BT_SAFETY_OFF    0
#define BT_SAFETY_NORMAL 1
#define BT_SAFETY_FULL   2

typedef struct bt_info bt_info;
struct bt_info {
  int eType;
  unsigned int pgno;
  sqlite4_buffer output;
};

#define BT_PAGERFILE_SHM      2
const char *sqlite4BtPagerFilename(BtPager*, int ePagerfile);

bt_env *sqlite4BtPagerGetEnv(BtPager*);
void sqlite4BtPagerSetEnv(BtPager*, bt_env*);

void sqlite4BtPagerSetSafety(BtPager*, int*);
void sqlite4BtPagerSetAutockpt(BtPager*, int*);

/*
** End of bt_pager.c interface.
*************************************************************************/

/*************************************************************************
** File-system interface.

  /* These three are set by the bt_pager module and thereafter used by 
  ** the bt_lock, bt_pager and bt_log modules. */
  sqlite4_env *pEnv;              /* SQLite environment */
  bt_env *pVfs;                   /* Bt environment */
  bt_file *pFd;                   /* Database file descriptor */
  int iDebugId;                   /* Sometimes useful when debugging */

  /* Global configuration settings:
  **
  ** nAutoCkpt:
  **   If a transaction is committed and there are this many frames in the
  **   log file, automatically run a checkpoint operation.
  **
  ** iSafetyLevel:
  **   Current safety level. 0==off, 1==normal, 2=full.
  */
  int iSafetyLevel;               /* 0==OFF, 1==NORMAL, 2==FULL */
  int nAutoCkpt;                  /* Auto-checkpoint when log is this large */

  /* These are used only by the bt_lock module. */
  BtShared *pShared;              /* Shared by all handles on this file */
  BtLock *pNext;                  /* Next connection using pShared */
  u32 mExclLock;                  /* Mask of exclusive locks held */
  u32 mSharedLock;                /* Mask of shared locks held */

};

struct BtReadSlot {
  u32 iFirst;
  u32 iLast;
};

#ifndef NDEBUG
static void btDebugCheckSnapshot(BtShmHdr *pHdr){
  u32 *aLog = pHdr->aLog;
  assert( pHdr->iNextFrame!=1 ||
      (aLog[0]==0 && aLog[1]==0 && aLog[2]==0 && aLog[3]==0)
  );

  /* Check that the three log regions do not overlap */
  assert( aLog[0]==0 || aLog[2]==0 || aLog[3]<aLog[0] || aLog[2]>aLog[1] );
  assert( aLog[0]==0 || aLog[4]==0 || aLog[5]<aLog[0] || aLog[4]>aLog[1] );
  assert( aLog[2]==0 || aLog[4]==0 || aLog[5]<aLog[2] || aLog[4]>aLog[3] );

  /* Check that the "next frame" does not overlap with any region */
  assert( aLog[0]==0 || pHdr->iNextFrame<aLog[0] ||  pHdr->iNextFrame>aLog[1] );
  assert( aLog[2]==0 || pHdr->iNextFrame<aLog[2] ||  pHdr->iNextFrame>aLog[3] );
  assert( aLog[4]==0 || pHdr->iNextFrame<aLog[4] ||  pHdr->iNextFrame>aLog[5] );
}
#else
#define btDebugCheckSnapshot(x)
#endif

#ifndef NDEBUG
static void btDebugCheckHash(BtLock *pLock){

static i64 btLogFrameOffset(BtLog *pLog, int pgsz, u32 iFrame){
  return 
      (i64)pLog->snapshot.nSector*2 
    + (i64)(iFrame-1) * (i64)(pgsz + sizeof(BtFrameHdr));
}

static int btLogSyncFile(BtLog *pLog, bt_file *pFd){
  if( pLog->pLock->iSafetyLevel==BT_SAFETY_OFF ) return SQLITE4_OK;
  bt_env *pVfs = pLog->pLock->pVfs;
  return pVfs->xSync(pFd);
}

static int btLogWriteData(BtLog *pLog, i64 iOff, u8 *aData, int nData){
  bt_env *pVfs = pLog->pLock->pVfs;
  return pVfs->xWrite(pLog->pFd, iOff, aData, nData);

  iNextFrame = pLog->snapshot.iNextFrame + 1;
  if( iFrame!=1 && iFrame==aLog[5]+1
   && aLog[0]==0 && aLog[2]==0 
   && aLog[4]!=0 && aLog[4]>pLog->nWrapLog 
  ){
    /* Case 2) It is possible to wrap the log around */
    iNextFrame = 1;
  }else if( (iNextFrame+nPad)>=aLog[0] && iNextFrame<=aLog[1] ){

    /* Case 3) It is necessary to jump over some existing log. */
    iNextFrame = aLog[1]+nPad+1;
    assert( iNextFrame!=1 );

    if( btLogFrameHash(pLog, iNextFrame)!=btLogFrameHash(pLog, iFrame) ){
      rc = btLogZeroHash(pLog, btLogFrameHash(pLog, iNextFrame));

/*
** Write a frame to the log file.
*/
int sqlite4BtLogWrite(BtLog *pLog, u32 pgno, u8 *aData, u32 nPg){
  const int pgsz = sqlite4BtPagerPagesize((BtPager*)(pLog->pLock));
  int rc = SQLITE4_OK;

  int nPad = 0;
  if( pLog->pLock->iSafetyLevel==BT_SAFETY_FULL ){
    nPad = (pLog->snapshot.nSector + pgsz-1) / pgsz;
  }

  /* If this is a commit frame and the size of the database has changed,
  ** ensure that the log file contains at least one copy of page 1 written
  ** since the last checkpoint. This is required as a future checkpoint
  ** will need to update the nPg field in the database header located on
  ** page 1. */
  if( nPg && nPg!=pLog->snapshot.nPg ){

  /* If this is a COMMIT, sync the log and update the shared shm-header. */
  if( nPg ){
    int i;
    for(i=0; i<nPad && rc==SQLITE4_OK; i++){
      rc = btLogWriteFrame(pLog, nPad, pgno, aData, nPg);
    }
    if( rc==SQLITE4_OK && pLog->pLock->iSafetyLevel==BT_SAFETY_FULL ){
      rc = btLogSyncFile(pLog, pLog->pFd);
    }
    if( rc==SQLITE4_OK ) rc = btLogUpdateSharedHdr(pLog);
  }

  return rc;
}

/*

    ** ascending order.  */
    if( rc==SQLITE4_OK ){
      rc = btLogGatherPgno(pLog, nFrameBuffer, &aPgno, &nPgno, &iLast);
    }

    if( rc==SQLITE4_OK && nPgno>0 ){
      i64 iOff = btLogFrameOffset(pLog, pgsz, iLast);

      /* Ensure the log has been synced to disk */
      if( rc==SQLITE4_OK ){
        rc = btLogSyncFile(pLog, pLog->pLock->pFd);
      }

      rc = btLogReadData(pLog, iOff, (u8*)&fhdr, sizeof(BtFrameHdr));
      iFirstRead = fhdr.iNext;

      /* Copy data from the log file to the database file. */
      for(i=0; rc==SQLITE4_OK && i<nPgno; i++){
        u32 pgno = aPgno[i];
        rc = btLogRead(pLog, pgno, aBuf, iLast);

    }

    case BT_CONTROL_SAFETY: {
      int *pInt = (int*)pArg;
      sqlite4BtPagerSetSafety(db->pPager, pInt);
      break;
    }

    case BT_CONTROL_AUTOCKPT: {
      int *pInt = (int*)pArg;
      sqlite4BtPagerSetAutockpt(db->pPager, pInt);
      break;
    }
  }

  return rc;
}

#include <assert.h>
#include <stdio.h>


/* By default auto-checkpoint is 1000 */
#define BT_DEFAULT_AUTOCKPT 1000

#define BT_DEFAULT_SAFETY BT_SAFETY_NORMAL

typedef struct BtPageHash BtPageHash;

typedef struct BtSavepoint BtSavepoint;
typedef struct BtSavepage BtSavepage;

/*
** Hash table for page references currently in memory. Manipulated using

/*
** Candidate values for BtPage.flags
*/
#define BT_PAGE_DIRTY 0x0001      /* Set for pages in BtPager.pDirty list */

/*
** Pager object.







*/
struct BtPager {
  BtLock btl;                     /* Variables shared with bt_lock module */
  BtLog *pLog;                    /* Logging module */
  int iTransactionLevel;          /* Current transaction level (see bt.h) */

  char *zFile;                    /* Database file name */
  int nFile;                      /* Length of string zFile in bytes */
  BtPageHash hash;                /* Hash table */
  BtPage *pDirty;                 /* List of all dirty pages */
  int nTotalRef;                  /* Total number of outstanding page refs */

  int bDoAutoCkpt;                /* Do auto-checkpoint after next unlock */
  BtSavepoint *aSavepoint;        /* Savepoint array */
  int nSavepoint;                 /* Number of entries in aSavepoint array */
  int pgsz;                       /* Page size in bytes */
  int nPg;                        /* Number of pages currently in db file */
};

  nByte = sizeof(BtPager) + nExtra;
  p = (BtPager*)sqlite4_malloc(pEnv, nByte);
  if( !p ) return btErrorBkpt(SQLITE4_NOMEM); 
  memset(p, 0, nByte);

  p->btl.pEnv = pEnv;
  p->btl.pVfs = sqlite4BtEnvDefault();
  p->btl.iSafetyLevel = BT_DEFAULT_SAFETY;
  p->btl.nAutoCkpt = BT_DEFAULT_AUTOCKPT;
  *pp = p;
  return SQLITE4_OK;
}

static void btFreePage(BtPager *p, BtPage *pPg){
  if( pPg ){
    sqlite4_free(p->btl.pEnv, pPg->aData);

  rc = sqlite4BtLogSnapshotClose(p->pLog);

  /* Purge the page cache. */
  assert( p->pDirty==0 );
  btPurgeCache(p);

  if( rc==SQLITE4_OK && p->bDoAutoCkpt ){
    sqlite4BtLogCheckpoint(p->pLog, (p->btl.nAutoCkpt / 2));
  }
  p->bDoAutoCkpt = 0;

  return rc;
}

/*

      int nPg = ((pNext==0) ? p->nPg : 0);
      rc = sqlite4BtLogWrite(p->pLog, pPg->pgno, pPg->aData, nPg);
    }
  }
  p->pDirty = 0;
  sqlite4BtLogSnapshotEndWrite(p->pLog);

  if( p->btl.nAutoCkpt && sqlite4BtLogSize(p->pLog)>=p->btl.nAutoCkpt ){
    p->bDoAutoCkpt = 1;
  }

  return rc;
}

static int btLoadPageData(BtPager *p, BtPage *pPg){

void sqlite4BtPagerSetEnv(BtPager *p, bt_env *pVfs){
  p->btl.pVfs = pVfs;
}

void sqlite4BtPagerSetSafety(BtPager *pPager, int *piVal){
  int iVal = *piVal;
  if( iVal>=0 && iVal<=2 ){
    pPager->btl.iSafetyLevel = iVal;
  }
  *piVal = pPager->btl.iSafetyLevel;
}

void sqlite4BtPagerSetAutockpt(BtPager *pPager, int *piVal){
  int iVal = *piVal;
  if( iVal>=0 ){
    pPager->btl.nAutoCkpt = iVal;
  }
  *piVal = pPager->btl.nAutoCkpt;
}

#ifndef NDEBUG
int sqlite4BtPagerRefcount(BtPager *p){
  return p->nTotalRef;
}
#endif