SQLite4  Check-in [d1b1a9e969]

static int testEnvSectorSize(lsm_file *pFile){
  lsm_env *pRealEnv = tdb_lsm_env();
  LsmFile *p = (LsmFile *)pFile;
  return pRealEnv->xSectorSize(p->pReal);
}

#if 0
static int testEnvRemap(
  lsm_file *pFile, 
  lsm_i64 iMin, 
  void **ppOut,
  lsm_i64 *pnOut
){
  lsm_env *pRealEnv = tdb_lsm_env();
  LsmFile *p = (LsmFile *)pFile;
  return pRealEnv->xRemap(p->pReal, iMin, ppOut, pnOut);
}
#endif

static int testEnvMap(
  lsm_file *pFile,
  lsm_i64 iOff,
  lsm_i64 nByte,
  void **ppOut,
  lsm_i64 *pszOut
){
  lsm_env *pRealEnv = tdb_lsm_env();
  LsmFile *p = (LsmFile *)pFile;
  return pRealEnv->xMap(p->pReal, iOff, nByte, ppOut, pszOut);
}

static int testEnvUnmap(
  lsm_file *pFile, 
  void *pMap, 
  lsm_i64 nMap
){
  lsm_env *pRealEnv = tdb_lsm_env();
  LsmFile *p = (LsmFile *)pFile;
  return pRealEnv->xUnmap(p->pReal, pMap, nMap);
}

static int testEnvFileid(
  lsm_file *pFile, 
  void *ppOut,
  int *pnOut
){
  lsm_env *pRealEnv = tdb_lsm_env();

  pDb->env.xFullpath = testEnvFullpath;
  pDb->env.xOpen = testEnvOpen;
  pDb->env.xRead = testEnvRead;
  pDb->env.xWrite = testEnvWrite;
  pDb->env.xTruncate = testEnvTruncate;
  pDb->env.xSync = testEnvSync;
  pDb->env.xSectorSize = testEnvSectorSize;
#if 0
  pDb->env.xRemap = testEnvRemap;
#endif
  pDb->env.xMap = testEnvMap;
  pDb->env.xUnmap = testEnvUnmap;
  pDb->env.xFileid = testEnvFileid;
  pDb->env.xClose = testEnvClose;
  pDb->env.xUnlink = testEnvUnlink;
  pDb->env.xLock = testEnvLock;
  pDb->env.xShmBarrier = testEnvShmBarrier;
  pDb->env.xShmMap = testEnvShmMap;
  pDb->env.xShmUnmap = testEnvShmUnmap;

#define LSM_LOCK_SHARED 1
#define LSM_LOCK_EXCL   2

/*
** CAPI: Database Runtime Environment
**
** Run-time environment used by LSM
**
** xMap(pFile, iOff, nByte, ppOut, pnOut):
**   Memory map nByte bytes of file pFile starting at file offset iOff. If
**   the file is less than (iOff+nByte) bytes in size extend it before 
**   mapping the new region. If successful, return LSM_OK and set *ppOut to
**   point to the mapped region. Set pnOut to the number of bytes mapped
**   (always nByte in this case). Otherwise, return an LSM error code.
**
**   If parameter iOff is zero, then nByte may be negative. In this case,
**   if the absolute value of nByte is greater than the size of the file
**   in bytes, then this is identical to a request with nByte set to a
**   positive value of the same magnitude. Or, if the file is more than
**   |nByte| bytes in size, the entire file should be mapped.
**
** xUnmap(pFile, nMap, pMap):
**   Argument pMap points to a mapping nMap bytes in size returned by a
**   previous invocation of xMap() on file pFile. Unmap it.
*/
struct lsm_env {
  int nByte;                 /* Size of this structure in bytes */
  int iVersion;              /* Version number of this structure (1) */
  /****** file i/o ***********************************************/
  void *pVfsCtx;
  int (*xFullpath)(lsm_env*, const char *, char *, int *);
  int (*xOpen)(lsm_env*, const char *, lsm_file **);
  int (*xRead)(lsm_file *, lsm_i64, void *, int);
  int (*xWrite)(lsm_file *, lsm_i64, void *, int);
  int (*xTruncate)(lsm_file *, lsm_i64);
  int (*xSync)(lsm_file *);
  int (*xSectorSize)(lsm_file *);
#if 0
  int (*xRemap)(lsm_file *, lsm_i64, void **, lsm_i64*);
#endif
  int (*xMap)(lsm_file *, lsm_i64 iOff, lsm_i64 nByte, void **, lsm_i64 *);
  int (*xUnmap)(lsm_file *, void *, lsm_i64);
  int (*xFileid)(lsm_file *, void *pBuf, int *pnBuf);
  int (*xClose)(lsm_file *);
  int (*xUnlink)(lsm_env*, const char *);
  int (*xLock)(lsm_file*, int, int);
  int (*xShmMap)(lsm_file*, int, int, void **);
  void (*xShmBarrier)(void);
  int (*xShmUnmap)(lsm_file*, int);

#define LSM_CONFIG_AUTOCHECKPOINT     12
#define LSM_CONFIG_SET_COMPRESSION    13
#define LSM_CONFIG_GET_COMPRESSION    14

#define LSM_SAFETY_OFF    0
#define LSM_SAFETY_NORMAL 1
#define LSM_SAFETY_FULL   2

#define LSM_MMAP_OFF     0
#define LSM_MMAP_FULL    1
#define LSM_MMAP_LIMITED 2

/*
** CAPI: Compression and/or Encryption Hooks
*/
struct lsm_compress {
  void *pCtx;
  unsigned int iId;

#define LSM_DFLT_BLOCK_SIZE         (1 * 1024 * 1024)
#define LSM_DFLT_AUTOFLUSH          (1 * 1024 * 1024)
#define LSM_DFLT_AUTOCHECKPOINT     (2 * 1024 * 1024)
#define LSM_DFLT_AUTOWORK           1
#define LSM_DFLT_LOG_SIZE           (128*1024)
#define LSM_DFLT_AUTOMERGE          4
#define LSM_DFLT_SAFETY             LSM_SAFETY_NORMAL
#define LSM_DFLT_MMAP               (LSM_IS_64_BIT ? LSM_MMAP_FULL : 0)
#define LSM_DFLT_MULTIPLE_PROCESSES 1
#define LSM_DFLT_USE_LOG            1

/* Initial values for log file checksums. These are only used if the 
** database file does not contain a valid checkpoint.  */
#define LSM_CKSUM0_INIT 42
#define LSM_CKSUM1_INIT 42

  int nTreeLimit;                 /* Configured by LSM_CONFIG_AUTOFLUSH */
  int nMerge;                     /* Configured by LSM_CONFIG_AUTOMERGE */
  int nLogSz;                     /* Configured by LSM_CONFIG_LOG_SIZE */
  int bUseLog;                    /* Configured by LSM_CONFIG_USE_LOG */
  int nDfltPgsz;                  /* Configured by LSM_CONFIG_PAGE_SIZE */
  int nDfltBlksz;                 /* Configured by LSM_CONFIG_BLOCK_SIZE */
  int nMaxFreelist;               /* Configured by LSM_CONFIG_MAX_FREELIST */
  int eMmap;                      /* Configured by LSM_CONFIG_MMAP */
  int nAutockpt;                  /* Configured by LSM_CONFIG_AUTOCHECKPOINT */
  int bMultiProc;                 /* Configured by L_C_MULTIPLE_PROCESSES */
  lsm_compress compress;          /* Compression callbacks */

  /* Sub-system handles */
  FileSystem *pFS;                /* On-disk portion of database */
  Database *pDatabase;            /* Database shared data */

*/
#include "lsmInt.h"

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

/*
** An object of this type provides an abstraction supporting the two 
** different mmap() strategies. See the fsMmapXXX() methods below for
** details.
*/
typedef struct MmapMgr MmapMgr;
typedef struct MmapMgrRef MmapMgrRef;

struct MmapMgr {
  int eUseMmap;                   /* LSM_MMAP_XXX mode */
  int nRef;                       /* Number of outstanding fsMmapRef() calls */

  /* Used when eUseMmap==LSM_MMAP_FULL */
  void *pMap;                     /* Current mapping of database file */
  i64 nMap;                       /* Bytes mapped at pMap */

  /* Used when eUseMmap==LSM_MMAP_LIMITED */
  int nEntry;                     /* Total number of currently mapped blocks */
  int nMapsz;                     /* Size of each mapping (default 1MB) */
  int nMaphash;                   /* Size of apHash[] in entries */
  MmapMgrRef **apHash;            /* Hash table of existing mappings */
  MmapMgrRef *pAll;               /* Linked list of all mappings */
  MmapMgrRef *pLast;              /* Last element in pAll list */
};

struct MmapMgrRef {
  void *pMap;                     /* Pointer to mapped memory */
  int nRef;                       /* Number of refs to this mapping */
  int iMap;                       /* Mapping number */
  MmapMgrRef *pNextHash;          /* Next mapped block with same hash key */
  MmapMgrRef *pNextAll;           /* Next mapped block in pAll list */
  MmapMgrRef *pPrevAll;           /* Previous mapped block in pAll list */
};

#define LSM_MAPPED_BLOCKS 16

/*
** File-system object. Each database connection allocates a single instance
** of the following structure. It is used for all access to the database and
** log files.
**
** eUseMmap:
**   This variable determines whether or not, and how, the lsm_env.xMap() is 
**   used to access the database file. It may be set to 0, 1 or 2. As follows:
**
**     0 - xMap() is not used at all.
**
**     1 - xMap() is used to map the entire database file.
**
**     2 - xMap() is used map 1MB blocks of the database file as required.
**         The library attempts to limit the number of mapped blocks to
**         LSM_MAPPED_BLOCKS at a time. This mode is intended for use on
**         32-bit platforms where mapping the entire database file may
**         not be possible due to the limited address space available.
**
** pLruFirst, pLruLast:
**   The first and last entries in a doubly-linked list of pages. The 
**   Page.pLruNext and Page.pLruPrev pointers are used to link the list
**   elements together.
**
**   In mmap() mode, this list contains all currently allocated pages that
**   are carrying pointers into the database file mapping (pMap/nMap). If the

  /* If this is a compressed database, a pointer to the compression methods.
  ** For an uncompressed database, a NULL pointer.  */
  lsm_compress *pCompress;
  u8 *aIBuffer;                   /* Buffer to compress to */
  u8 *aOBuffer;                   /* Buffer to uncompress from */
  int nBuffer;                    /* Allocated size of aBuffer[] in bytes */

  /* State variables used in mmap() mode. */
  MmapMgr mmapmgr;


  Page *pFree;

  Page *pWaiting;                 /* b-tree pages waiting to be written */

  /* Statistics */
  int nWrite;                     /* Total number of pages written */
  int nRead;                      /* Total number of pages read */

**   The lsmFsSortedAppend() function sets the pSeg pointer to point to the
**   segment that the new page will be a part of. It is unset by
**   lsmFsPagePersist() after the page is written to disk.
*/
struct Page {
  u8 *aData;                      /* Buffer containing page data */
  int nData;                      /* Bytes of usable data at aData[] */
  MmapMgrRef *pRef;               /* Mapping manager reference token */
  Pgno iPg;                       /* Page number */
  int nRef;                       /* Number of outstanding references */
  int flags;                      /* Combination of PAGE_XXX flags */
  Page *pHashNext;                /* Next page in hash table slot */
  Page *pLruNext;                 /* Next page in LRU list */
  Page *pLruPrev;                 /* Previous page in LRU list */
  FileSystem *pFS;                /* File system that owns this page */

** Meta-data page handle. There are two meta-data pages at the start of
** the database file, each FileSystem.nMetasize bytes in size.
*/
struct MetaPage {
  int iPg;                        /* Either 1 or 2 */
  int bWrite;                     /* Write back to db file on release */
  u8 *aData;                      /* Pointer to buffer */
  MmapMgrRef *pRef;               /* Mmap manager reference token */
  FileSystem *pFS;                /* FileSystem that owns this page */
};

/* 
** Values for LsmPage.flags 
*/
#define PAGE_DIRTY   0x00000001   /* Set if page is dirty */

}
static int lsmEnvTruncate(lsm_env *pEnv, lsm_file *pFile, lsm_i64 nByte){
  return IOERR_WRAPPER( pEnv->xTruncate(pFile, nByte) );
}
static int lsmEnvUnlink(lsm_env *pEnv, const char *zDel){
  return IOERR_WRAPPER( pEnv->xUnlink(pEnv, zDel) );
}
#if 0
static int lsmEnvRemap(
  lsm_env *pEnv, 
  lsm_file *pFile, 
  i64 szMin,
  void **ppMap,
  i64 *pszMap
){
  return pEnv->xRemap(pFile, szMin, ppMap, pszMap);
}
#endif
static void lsmEnvUnmap(
  lsm_env *pEnv, 
  lsm_file *pFile, 
  void *pMap, 
  lsm_i64 nMap
){
  pEnv->xUnmap(pFile, pMap, nMap);
}
static int lsmEnvMap(
  lsm_env *pEnv, 
  lsm_file *pFile, 
  i64 iOff,
  i64 szMin,
  void **ppMap,
  i64 *pszMap
){
  return pEnv->xMap(pFile, iOff, szMin, ppMap, pszMap);
}

int lsmEnvLock(lsm_env *pEnv, lsm_file *pFile, int iLock, int eLock){
  if( pFile==0 ) return LSM_OK;
  return pEnv->xLock(pFile, iLock, eLock);
}

int lsmEnvShmMap(

** Close the log file. Then delete it from the file-system. This function
** is called during database shutdown only.
*/
int lsmFsCloseAndDeleteLog(FileSystem *pFS){
  char *zDel;

  if( pFS->fdLog ){
    lsmEnvClose(pFS->pEnv, pFS->fdLog);
    pFS->fdLog = 0;
  }

  zDel = lsmMallocPrintf(pFS->pEnv, "%s-log", pFS->zDb);
  if( zDel ){
    lsmEnvUnlink(pFS->pEnv, zDel);
    lsmFree(pFS->pEnv, zDel);

  lsm_file *pFile = 0;
  if( *pRc==LSM_OK ){
    *pRc = lsmEnvOpen(pFS->pEnv, (bLog ? pFS->zLog : pFS->zDb), &pFile);
  }
  return pFile;
}


static void fsGrowMapping(
  FileSystem *pFS,
  i64 iSz,
  int *pRc
){
  MmapMgr *p = &pFS->mmapmgr;

  /* This function won't work with compressed databases yet. */
  assert( pFS->pCompress==0 );
  assert( PAGE_HASPREV==4 );
  assert( p->eUseMmap==LSM_MMAP_FULL );

  if( *pRc==LSM_OK && iSz>p->nMap ){
    int rc;
    u8 *aOld = p->pMap;
    if( aOld ){
      lsmEnvUnmap(pFS->pEnv, pFS->fdDb, aOld, p->nMap);
      p->pMap = 0;
    }
    rc = lsmEnvMap(pFS->pEnv, pFS->fdDb, 0, iSz, &p->pMap, &p->nMap);

    if( rc==LSM_OK && p->pMap!=aOld ){
      Page *pFix;
      i64 iOff = (u8 *)p->pMap - aOld;
      for(pFix=pFS->pLruFirst; pFix; pFix=pFix->pLruNext){
        pFix->aData += iOff;
      }
      lsmSortedRemap(pFS->pDb);
    }
    *pRc = rc;
  }
}

/* 
** Remove this block from the pAll list 
*/
static void fsMmapRemoveFromAll(MmapMgr *p, MmapMgrRef *pRef){
  if( pRef->pPrevAll ){
    pRef->pPrevAll->pNextAll = pRef->pNextAll;
  }else{
    assert( pRef==p->pAll );
    p->pAll = pRef->pNextAll;
  }

  if( pRef->pNextAll ){
    pRef->pNextAll->pPrevAll = pRef->pPrevAll;
  }else{
    assert( pRef==p->pLast );
    p->pLast = pRef->pPrevAll;
  }

  pRef->pNextAll = 0;
  pRef->pPrevAll = 0;
}

/* 
** Add this block to the pAll list. To the start if bLast==0, or the end
** if bLast==1.
*/
static void fsMmapAddToAll(MmapMgr *p, MmapMgrRef *pRef, int bLast){
  if( bLast ){
    assert( p->pLast==0 || p->pLast->pNextAll==0 );
    if( p->pLast ){
      p->pLast->pNextAll = pRef;
    }else{
      p->pAll = pRef;
    }
    pRef->pPrevAll = p->pLast;
    p->pLast = pRef;
  }else{
    assert( p->pAll==0 || p->pAll->pPrevAll==0 );
    if( p->pAll ){
      p->pAll->pPrevAll = pRef;
    }else{
      p->pLast = pRef;
    }
    pRef->pNextAll = p->pAll;
    p->pAll = pRef;
  }
}

/*
** Obtain a reference to a mapping of the database file.
*/
static void *fsMmapRef(
  FileSystem *pFS,                /* Memory map manager object */
  i64 iOff,                       /* File offset to return reference to */
  int nByte,                      /* Size of referenced block */
  MmapMgrRef **ppRef,             /* OUT: Reference used to free memory */
  int *pRc                        /* IN/OUT: Error code */
){
  lsm_env *pEnv = pFS->pEnv;
  MmapMgr *p = &pFS->mmapmgr;
  void *pRet = 0;
  int rc = *pRc;

  assert( iOff>=0 && nByte>0 );
  assert( p->eUseMmap!=LSM_MMAP_OFF );
  assert( *ppRef==0 );

  if( p->eUseMmap==LSM_MMAP_FULL ){
    fsGrowMapping(pFS, iOff+nByte, &rc);
    if( rc==LSM_OK ){
      pRet = (void *)&((u8 *)p->pMap)[iOff];
      *ppRef = (MmapMgrRef *)pRet;
    }
  }else{
    MmapMgrRef *pRef = 0;         /* Mapping reference */

    /* If the hash table has not been allocated, allocate it now. */
    if( p->apHash==0 ){
      int nSz = sizeof(MmapMgrRef *) * LSM_MAPPED_BLOCKS * 2;
      p->apHash = (MmapMgrRef **)lsmMallocZeroRc(pEnv, nSz, &rc);
      p->nMaphash = LSM_MAPPED_BLOCKS * 2;
    }

    if( rc==LSM_OK ){
      int iMap = (iOff / p->nMapsz);

      /* Search the hash table for the required mapping */
      int iHash = fsHashKey(p->nMaphash, iMap);
      for(pRef=p->apHash[iHash]; pRef; pRef=pRef->pNextHash){
        if( pRef->iMap==iMap ) break;
      }

      if( pRef ){
        /* Mapping was found. */
        fsMmapRemoveFromAll(p, pRef);
      }else{
        /* We have no existing mapping for mapping block iMap. */
        if( p->nEntry>=LSM_MAPPED_BLOCKS && p->pAll->nRef==0 ){
          MmapMgrRef **pp;
          int iHash2;
          pRef = p->pAll;

          /* Unmap this blocks mapping */ 
          lsmEnvUnmap(pFS->pEnv, pFS->fdDb, pRef->pMap, p->nMapsz); 
          pRef->pMap = 0;

          /* Remove this mapped block from the hash table */
          iHash2 = fsHashKey(p->nMaphash, pRef->iMap);
          for(pp=&p->apHash[iHash2]; *pp!=pRef; pp = &((*pp)->pNextHash));
          *pp = (*pp)->pNextHash;
          pRef->pNextHash = 0;

          /* Remove this mapped block from the pAll list */
          fsMmapRemoveFromAll(p, pRef);
#if 0
          printf("recycling mapping %d -> %d\n", pRef->iMap, iMap);
#endif

        }else{
          pRef = (MmapMgrRef *)lsmMallocZeroRc(pEnv, sizeof(MmapMgrRef), &rc);
          if( pRef ) p->nEntry++;
          assert( p->nEntry<20 );
        }

        if( rc==LSM_OK ){
          i64 dummy;
          rc = lsmEnvMap(pEnv, 
              pFS->fdDb, (i64)iMap*p->nMapsz, p->nMapsz, &pRef->pMap, &dummy
          );
          if( rc==LSM_OK ){
            /* Link the mapped block into the hash table */
            pRef->pNextHash = p->apHash[iHash];
            pRef->iMap = iMap;
            p->apHash[iHash] = pRef;
          }
        }
      }

      if( rc==LSM_OK ){
        pRef->nRef++;
        pRet = (void *)&((u8 *)(pRef->pMap))[iOff % p->nMapsz];
        fsMmapAddToAll(p, pRef, 1);
        *ppRef = pRef;
      }else{
        lsmFree(pEnv, pRef);
      } 
    }
  }

  *pRc = rc;
  if( rc==LSM_OK ) p->nRef++;
  return pRet;
}

/*
** Release a reference returned by an earlier call to fsMmapRef().
*/
static void fsMmapUnref(FileSystem *pFS, MmapMgrRef **ppRef){
  MmapMgr *p = &pFS->mmapmgr;
  MmapMgrRef *pRef = *ppRef;

  assert( p->eUseMmap!=LSM_MMAP_OFF );
  if( pRef ){
    p->nRef--;

    if( p->eUseMmap==LSM_MMAP_LIMITED ){
      pRef->nRef--;
      assert( pRef->nRef>=0 );
      if( pRef->nRef==0 ){
        fsMmapRemoveFromAll(p, pRef);
        fsMmapAddToAll(p, pRef, 0);
      }
    }
  }

  *ppRef = 0;
  assert( p->nRef>=0 );
}

/*
** Unmap all currently mapped blocks. Release all allocated memory.
*/
static void fsMmapClose(FileSystem *pFS){
  MmapMgr *p = &pFS->mmapmgr;
  assert( p->nRef==0 );
  if( p->eUseMmap==LSM_MMAP_FULL ){
    if( p->pMap ){
      lsmEnvUnmap(pFS->pEnv, pFS->fdDb, p->pMap, p->nMap); 
      p->pMap = 0;
      p->nMap = 0;
    }
  }
  else if( p->eUseMmap==LSM_MMAP_LIMITED ){
    MmapMgrRef *pRef;
    MmapMgrRef *pNext;
    for(pRef=p->pAll; pRef; pRef=pNext){
      pNext = pRef->pNextAll;
      lsmEnvUnmap(pFS->pEnv, pFS->fdDb, pRef->pMap, p->nMapsz);
      lsmFree(pFS->pEnv, pRef);
    }
    lsmFree(pFS->pEnv, p->apHash);
    p->nEntry = 0;
    p->nMaphash = 0;
    p->apHash = 0;
    p->pAll = 0;
    p->pLast = 0;
  }
}

/*
** If it is not already open, this function opens the log file. It returns
** LSM_OK if successful (or if the log file was already open) or an LSM
** error code otherwise.
**
** The log file must be opened before any of the following may be called:
**

    pFS->nBlocksize = LSM_DFLT_BLOCK_SIZE;
    pFS->nMetasize = 4 * 1024;
    pFS->pDb = pDb;
    pFS->pEnv = pDb->pEnv;
    if( pDb->compress.xCompress ){
      pFS->pCompress = &pDb->compress;
    }else{
      pFS->mmapmgr.eUseMmap = pDb->eMmap;
      pFS->mmapmgr.nMapsz = 1*1024*1024;
    }

    /* Make a copy of the database and log file names. */
    memcpy(pFS->zDb, zDb, nDb+1);
    memcpy(pFS->zLog, zDb, nDb);
    memcpy(&pFS->zLog[nDb], "-log", 5);

    while( pPg ){
      Page *pNext = pPg->pLruNext;
      if( pPg->flags & PAGE_FREE ) lsmFree(pEnv, pPg->aData);
      lsmFree(pEnv, pPg);
      pPg = pNext;
    }

    fsMmapClose(pFS);
    if( pFS->fdDb ) lsmEnvClose(pFS->pEnv, pFS->fdDb );
    if( pFS->fdLog ) lsmEnvClose(pFS->pEnv, pFS->fdLog );
    lsmFree(pEnv, pFS->pLsmFile);
    lsmFree(pEnv, pFS->apHash);
    lsmFree(pEnv, pFS->aIBuffer);
    lsmFree(pEnv, pFS->aOBuffer);
    lsmFree(pEnv, pFS);
  }
}

void lsmFsDeferClose(FileSystem *pFS, LsmFile **pp){
  LsmFile *p = pFS->pLsmFile;
  assert( p->pNext==0 );
  fsMmapClose(pFS);
  p->pFile = pFS->fdDb;
  pFS->fdDb = 0;
  pFS->pLsmFile = 0;
  *pp = p;
}

/*

  Page **pp;

  iHash = fsHashKey(pFS->nHash, pPg->iPg);
  for(pp=&pFS->apHash[iHash]; *pp!=pPg; pp=&(*pp)->pHashNext);
  *pp = pPg->pHashNext;
}

/*
** This function is only called if FileSystem.eUseMmap==0 (i.e. in non-mmap
** mode).
*/
static int fsPageBuffer(
  FileSystem *pFS, 

  Page **ppOut
){
  int rc = LSM_OK;
  Page *pPage = 0;

  if( pFS->mmapmgr.eUseMmap!=LSM_MMAP_OFF
   || pFS->pLruFirst==0 
   || pFS->nCacheAlloc<pFS->nCacheMax 
  ){
    pPage = lsmMallocZero(pFS->pEnv, sizeof(Page));
    if( !pPage ){
      rc = LSM_NOMEM_BKPT;
    }else{
      pPage->aData = (u8 *)lsmMalloc(pFS->pEnv, pFS->nPagesize);
      pPage->flags = PAGE_FREE;
      if( !pPage->aData ){
        lsmFree(pFS->pEnv, pPage);
        rc = LSM_NOMEM_BKPT;
        pPage = 0;
      }
      pFS->nCacheAlloc++;


    }
  }else{
    pPage = pFS->pLruFirst;
    fsPageRemoveFromLru(pFS, pPage);
    fsPageRemoveFromHash(pFS, pPage);
  }

  assert( pPage==0 || (pPage->flags & PAGE_DIRTY)==0 );
  *ppOut = pPage;
  return rc;
}

static void fsPageBufferFree(Page *pPg){
  FileSystem *pFS = pPg->pFS;
  assert( pFS->mmapmgr.eUseMmap==LSM_MMAP_OFF );

  if( pPg->flags & PAGE_FREE ){
    lsmFree(pPg->pFS->pEnv, pPg->aData);
  }



  lsmFree(pPg->pFS->pEnv, pPg);
}



























/*
** fsync() the database file.
*/
int lsmFsSyncDb(FileSystem *pFS, int nBlock){
#if 0
  if( nBlock && pFS->bUseMmap ){
    int rc = LSM_OK;
    i64 nMin = (i64)nBlock * (i64)pFS->nBlocksize;
    fsGrowMapping(pFS, nMin, &rc);
    if( rc!=LSM_OK ) return rc;
  }
#endif
  return lsmEnvSync(pFS->pEnv, pFS->fdDb);
}

static int fsPageGet(FileSystem *, Segment *, Pgno, int, Page **, int *);

static int fsRedirectBlock(Redirect *p, int iBlk){
  if( p ){

  
  if( pSeg ){
    iRead = fsRedirectBlock(pSeg->pRedirect, iBlock);
  }else{
    iRead = iBlock;
  }

  assert( pFS->mmapmgr.eUseMmap==LSM_MMAP_OFF || pFS->pCompress==0 );
  if( pFS->pCompress ){
    i64 iOff;                     /* File offset to read data from */
    u8 aNext[4];                  /* 4-byte pointer read from db file */

    iOff = (i64)iRead * pFS->nBlocksize - sizeof(aNext);
    rc = lsmEnvRead(pFS->pEnv, pFS->fdDb, iOff, aNext, sizeof(aNext));
    if( rc==LSM_OK ){

  FileSystem *pFS,                /* File-system object handle */
  Segment *pSeg,                  /* Use this segment for block redirects */
  int iBlock,                     /* Read field from this block */
  int *piPrev                     /* OUT: Previous block in linked list */
){
  int rc = LSM_OK;                /* Return code */

  assert( pFS->mmapmgr.eUseMmap==LSM_MMAP_OFF || pFS->pCompress==0 );
  assert( iBlock>0 );

  if( pFS->pCompress ){
    i64 iOff = fsFirstPageOnBlock(pFS, iBlock) - 4;
    u8 aPrev[4];                  /* 4-byte pointer read from db file */
    rc = lsmEnvRead(pFS->pEnv, pFS->fdDb, iOff, aPrev, sizeof(aPrev));
    if( rc==LSM_OK ){

  int iHash;
  int rc = LSM_OK;

  /* In most cases iReal is the same as iPg. Except, if pSeg->pRedirect is 
  ** not NULL, and the block containing iPg has been redirected, then iReal
  ** is the page number after redirection.  */
  Pgno iReal = lsmFsRedirectPage(pFS, (pSeg ? pSeg->pRedirect : 0), iPg);
  i64 iOff = (i64)(iReal-1) * pFS->nPagesize;

  assert( iPg>=fsFirstPageOnBlock(pFS, 1) );
  assert( iReal>=fsFirstPageOnBlock(pFS, 1) );
  *ppPg = 0;

  assert( pFS->mmapmgr.eUseMmap==LSM_MMAP_OFF || pFS->pCompress==0 );
  if( pFS->mmapmgr.eUseMmap!=LSM_MMAP_OFF ){
    Page *pTest;




    /* Check if the page is currently in the waiting list. If so, increment
    ** the refcount and return a pointer to it. No more to do in this case. */
    p = 0;
    for(pTest=pFS->pWaiting; pTest; pTest=pTest->pNextWaiting){
      if( pTest->iPg==iReal ){
        assert( iReal==iPg );
        p = pTest;
        p->nRef++;
        *ppPg = p;
        return LSM_OK;
      }
    }

    /* Allocate or recycle a Page structure */
    if( pFS->pFree ){
      p = pFS->pFree;
      pFS->pFree = p->pHashNext;
      assert( p->nRef==0 );
    }else{
      p = lsmMallocZeroRc(pFS->pEnv, sizeof(Page), &rc);
      if( rc ) return rc;
      fsPageAddToLru(pFS, p);
      p->pFS = pFS;
    }

    p->iPg = iReal;

    p->aData = fsMmapRef(pFS, iOff, pFS->nPagesize, &p->pRef, &rc);
    if( rc!=LSM_OK ){
      lsmFsPageRelease(p);
      p = 0;
    }
  }else{

    /* Search the hash-table for the page */
    iHash = fsHashKey(pFS->nHash, iReal);
    for(p=pFS->apHash[iHash]; p; p=p->pHashNext){
      if( p->iPg==iReal) break;
    }

    if( p==0 ){
      rc = fsPageBuffer(pFS, &p);
      if( rc==LSM_OK ){
        int nSpace = 0;
        p->iPg = iReal;
        p->nRef = 0;
        p->pFS = pFS;
        assert( p->flags==0 || p->flags==PAGE_FREE );

#ifdef LSM_DEBUG
        memset(p->aData, 0x56, pFS->nPagesize);
#endif
        assert( p->pLruNext==0 && p->pLruPrev==0 );
        if( noContent==0 ){
          if( pFS->pCompress ){
            rc = fsReadPagedata(pFS, pSeg, p, &nSpace);
          }else{
            int nByte = pFS->nPagesize;

            rc = lsmEnvRead(pFS->pEnv, pFS->fdDb, iOff, p->aData, nByte);
          }
          pFS->nRead++;
        }

        /* If the xRead() call was successful (or not attempted), link the
         ** page into the page-cache hash-table. Otherwise, if it failed,

** may be garbage. It is the callers responsibility to deal with this.
*/
int lsmFsReadSyncedId(lsm_db *db, int iMeta, i64 *piVal){
  FileSystem *pFS = db->pFS;
  int rc = LSM_OK;

  assert( iMeta==1 || iMeta==2 );
  if( pFS->mmapmgr.eUseMmap!=LSM_MMAP_OFF ){
    MmapMgrRef *pRef = 0;
    u8 *pMap;                     /* Mapping of two meta pages */

    pMap = (u8 *)fsMmapRef(pFS, 0, LSM_META_PAGE_SIZE*2, &pRef, &rc);
    if( rc==LSM_OK ){
      *piVal = (i64)lsmGetU64(&pMap[(iMeta-1)*LSM_META_PAGE_SIZE]);
      fsMmapUnref(pFS, &pRef);
    }
  }else{
    MetaPage *pMeta = 0;
    rc = lsmFsMetaPageGet(pFS, 0, iMeta, &pMeta);
    if( rc==LSM_OK ){
      *piVal = (i64)lsmGetU64(pMeta->aData);
      lsmFsMetaPageRelease(pMeta);

  assert( p->pRedirect==0 );

  if( pFS->pCompress || bDefer ){
    /* In compressed database mode the page is not assigned a page number
    ** or location in the database file at this point. This will be done
    ** by the lsmFsPagePersist() call.  */
    rc = fsPageBuffer(pFS, &pPg);
    if( rc==LSM_OK ){
      pPg->pFS = pFS;
      pPg->pSeg = p;
      pPg->iPg = 0;
      pPg->flags |= PAGE_DIRTY;
      pPg->nData = pFS->nPagesize;
      assert( pPg->aData );

  MetaPage *pPg;
  assert( iPg==1 || iPg==2 );

  pPg = lsmMallocZeroRc(pFS->pEnv, sizeof(Page), &rc);

  if( pPg ){
    i64 iOff = (iPg-1) * pFS->nMetasize;
    if( pFS->mmapmgr.eUseMmap!=LSM_MMAP_OFF ){

      pPg->aData = fsMmapRef(pFS, iOff, LSM_META_PAGE_SIZE, &pPg->pRef, &rc);
    }else{
      pPg->aData = lsmMallocRc(pFS->pEnv, pFS->nMetasize, &rc);
      if( rc==LSM_OK && bWrite==0 ){
        rc = lsmEnvRead(pFS->pEnv, pFS->fdDb, iOff, pPg->aData, pFS->nMetasize);
      }
#ifndef NDEBUG
      /* pPg->aData causes an uninitialized access via a downstreadm write().
         After discussion on this list, this memory should not, for performance
         reasons, be memset. However, tracking down "real" misuse is more
         difficult with this "false" positive, so it is set when NDEBUG.
      */
      else if( rc==LSM_OK ){
        memset( pPg->aData, 0x77, pFS->nMetasize );
      }
#endif
    }

    if( rc!=LSM_OK ){
      if( pFS->mmapmgr.eUseMmap==LSM_MMAP_OFF ){
        lsmFree(pFS->pEnv, pPg->aData);
      }else{
        fsMmapUnref(pFS, &pPg->pRef);
      }
      lsmFree(pFS->pEnv, pPg);
      pPg = 0;
    }else{
      pPg->iPg = iPg;
      pPg->bWrite = bWrite;
      pPg->pFS = pFS;
    }

** Release a meta-page reference obtained via a call to lsmFsMetaPageGet().
*/
int lsmFsMetaPageRelease(MetaPage *pPg){
  int rc = LSM_OK;
  if( pPg ){
    FileSystem *pFS = pPg->pFS;

    if( pFS->mmapmgr.eUseMmap==LSM_MMAP_OFF ){
      if( pPg->bWrite ){
        i64 iOff = (pPg->iPg==2 ? pFS->nMetasize : 0);
        int nWrite = pFS->nMetasize;
        rc = lsmEnvWrite(pFS->pEnv, pFS->fdDb, iOff, pPg->aData, nWrite);
      }
      lsmFree(pFS->pEnv, pPg->aData);
    }else{
      fsMmapUnref(pFS, &pPg->pRef);
    }

    lsmFree(pFS->pEnv, pPg);
  }
  return rc;
}

  i64 iFromOff = (i64)(iFrom-1) * pFS->nBlocksize;
  i64 iToOff = (i64)(iTo-1) * pFS->nBlocksize;
  
  assert( iTo!=1 );
  assert( iFrom>iTo );

  if( pFS->mmapmgr.eUseMmap!=LSM_MMAP_OFF ){
    MmapMgrRef *pRef1 = 0;
    MmapMgrRef *pRef2 = 0;
    void *pTo, *pFrom;

    pTo = fsMmapRef(pFS, iToOff, pFS->nBlocksize, &pRef1, &rc);
    pFrom = fsMmapRef(pFS, iFromOff, pFS->nBlocksize, &pRef2, &rc);
    if( rc==LSM_OK ){

      memcpy(pTo, pFrom, pFS->nBlocksize);
    }
    fsMmapUnref(pFS, &pRef1);
    fsMmapUnref(pFS, &pRef2);

  }else{
    int nSz = pFS->nPagesize;
    u8 *aData = (u8 *)lsmMallocRc(pFS->pEnv, nSz, &rc);
    if( rc==LSM_OK ){
      const int nPagePerBlock = (pFS->nBlocksize / pFS->nPagesize);
      int i;
      for(i=0; rc==LSM_OK && i<nPagePerBlock; i++){

        assert( pPg->flags & PAGE_FREE );
        assert( (pPg->flags & PAGE_HASPREV)==0 );
        assert( pPg->nData==pFS->nPagesize-4 );

        rc = fsAppendPage(pFS, pPg->pSeg, &pPg->iPg, &iPrev, &iNext);
        if( rc!=LSM_OK ) return rc;

        if( pFS->mmapmgr.eUseMmap==LSM_MMAP_OFF ){
          int iHash = fsHashKey(pFS->nHash, pPg->iPg);
          pPg->pHashNext = pFS->apHash[iHash];
          pFS->apHash[iHash] = pPg;
          assert( pPg->pHashNext==0 || pPg->pHashNext->iPg!=pPg->iPg );
        }

        if( iPrev ){

        *pp = pPg;
        assert( pPg->pNextWaiting==0 );

      }else{
        i64 iOff;                   /* Offset to write within database file */

        iOff = (i64)pFS->nPagesize * (i64)(pPg->iPg-1);
        if( pFS->mmapmgr.eUseMmap==0 ){
          u8 *aData = pPg->aData - (pPg->flags & PAGE_HASPREV);
          rc = lsmEnvWrite(pFS->pEnv, pFS->fdDb, iOff, aData, pFS->nPagesize);
        }else if( pPg->flags & PAGE_FREE ){
          u8 *aTo = (u8 *)fsMmapRef(pFS, iOff, pFS->nPagesize, &pPg->pRef, &rc);
          if( rc==LSM_OK ){

            u8 *aFrom = pPg->aData - (pPg->flags & PAGE_HASPREV);
            memcpy(aTo, aFrom, pFS->nPagesize);
            lsmFree(pFS->pEnv, aFrom);
            pPg->aData = aTo + (pPg->flags & PAGE_HASPREV);
            pPg->flags &= ~PAGE_FREE;
            fsPageAddToLru(pFS, pPg);
          }

      assert( pPg->pFS->pCompress 
           || fsIsFirst(pPg->pFS, pPg->iPg)==0 
           || (pPg->flags & PAGE_HASPREV)
      );
      pPg->aData -= (pPg->flags & PAGE_HASPREV);
      pPg->flags &= ~PAGE_HASPREV;

      if( pFS->mmapmgr.eUseMmap!=LSM_MMAP_OFF ){
        fsMmapUnref(pFS, &pPg->pRef);
        pPg->pHashNext = pFS->pFree;
        pFS->pFree = pPg;
      }else{
        assert( pPg->pLruNext==0 );
        assert( pPg->pLruPrev==0 );
        fsPageRemoveFromHash(pFS, pPg);
        fsPageBufferFree(pPg);

  pDb->nDfltPgsz = LSM_DFLT_PAGE_SIZE;
  pDb->nDfltBlksz = LSM_DFLT_BLOCK_SIZE;
  pDb->nMerge = LSM_DFLT_AUTOMERGE;
  pDb->nMaxFreelist = LSM_MAX_FREELIST_ENTRIES;
  pDb->bUseLog = LSM_DFLT_USE_LOG;
  pDb->iReader = -1;
  pDb->bMultiProc = LSM_DFLT_MULTIPLE_PROCESSES;
  pDb->eMmap = LSM_DFLT_MMAP;
  pDb->xLog = xLog;
  return LSM_OK;
}

lsm_env *lsm_get_env(lsm_db *pDb){
  assert( pDb->pEnv );
  return pDb->pEnv;

      }
      *piVal = pDb->eSafety;
      break;
    }

    case LSM_CONFIG_MMAP: {
      int *piVal = va_arg(ap, int *);
      if( pDb->pDatabase==0 && (*piVal>=0 && *piVal<=2) ){
        pDb->eMmap = *piVal;
      }
      *piVal = pDb->eMmap;
      break;
    }

    case LSM_CONFIG_USE_LOG: {
      int *piVal = va_arg(ap, int *);
      if( pDb->nTransOpen==0 && (*piVal==0 || *piVal==1) ){
        pDb->bUseLog = *piVal;

  return rc;
}

static int lsmPosixOsSectorSize(lsm_file *pFile){
  return 512;
}

static int lsmPosixOsMap(
  lsm_file *pFile,
  lsm_i64 iOff,
  lsm_i64 nByte,
  void **ppOut,
  lsm_i64 *pszOut
){
  PosixFile *p = (PosixFile *)pFile;
  off_t off = (off_t)iOff;
  int prc;                        /* Posix Return Code */
  struct stat buf;
  size_t sz;

  memset(&buf, 0, sizeof(buf));
  prc = fstat(p->fd, &buf);
  if( prc!=0 ) return LSM_IOERR_BKPT;

  if( nByte<=0 ){
    sz = (size_t)(LSM_MAX(nByte*-1, (i64)buf.st_size));
  }else{
    sz = (size_t)nByte;
  }
  sz = (size_t)(LSM_MAX(sz, 1<<15));

  if( (off+sz)>buf.st_size ){
    prc = ftruncate(p->fd, (off+sz));
    if( prc!=0 ) return LSM_IOERR_BKPT;
  }

  *ppOut = mmap(0, sz, PROT_READ|PROT_WRITE, MAP_SHARED, p->fd, off);
  if( *ppOut==0 ) return LSM_IOERR_BKPT;

  *pszOut = (i64)sz;
  return LSM_OK;
}

static int lsmPosixOsUnmap(
  lsm_file *pFile, 
  void *pMap, 
  lsm_i64 nMap
){
  PosixFile *p = (PosixFile *)pFile;
  munmap(pMap, (size_t)nMap);
  return LSM_OK;
}

static int lsmPosixOsRemap(
  lsm_file *pFile, 
  lsm_i64 iMin, 
  void **ppOut,
  lsm_i64 *pnOut
){

    lsmPosixOsFullpath,      /* xFullpath */
    lsmPosixOsOpen,          /* xOpen */
    lsmPosixOsRead,          /* xRead */
    lsmPosixOsWrite,         /* xWrite */
    lsmPosixOsTruncate,      /* xTruncate */
    lsmPosixOsSync,          /* xSync */
    lsmPosixOsSectorSize,    /* xSectorSize */
#if 0
    lsmPosixOsRemap,         /* xRemap */
#endif
    lsmPosixOsMap,           /* xMap */
    lsmPosixOsUnmap,         /* xUnmap */
    lsmPosixOsFileid,        /* xFileid */
    lsmPosixOsClose,         /* xClose */
    lsmPosixOsUnlink,        /* xUnlink */
    lsmPosixOsLock,          /* xLock */
    lsmPosixOsShmMap,        /* xShmMap */
    lsmPosixOsShmBarrier,    /* xShmBarrier */
    lsmPosixOsShmUnmap,      /* xShmUnmap */

    puts "sleeping 20 seconds..." ; after $nSleep
    run_speed_test res.db 900 $nInsert $nSelect $nPause 200 $config $name
  }
}

#run_all_tests

if 0 {
generate_chart png res.db 1 2
update
capture_photo lsmperf1.gif
destroy .c

generate_chart png res.db 3 4
update
capture_photo lsmperf2.gif
destroy .c

generate_chart png res.db 5 6
update
capture_photo lsmperf3.gif
destroy .c
}

run_speed_test res.db 900 20000 20000 0 100 "mmap=2" mmap=2
after 10000
run_speed_test res.db 900 20000 20000 0 100 "mmap=0" mmap=0
generate_chart png res.db 1 2
update
#capture_photo lsmperf.gif
#destroy .c

#exit