SQLite4  Check-in [3b2a50c089]

/* Lock definitions. */
#define LSM_LOCK_DMS1         1   /* Serialize connect/disconnect ops */
#define LSM_LOCK_DMS2         2   /* Read-write connections */
#define LSM_LOCK_DMS3         3   /* Read-only connections */
#define LSM_LOCK_WRITER       4
#define LSM_LOCK_WORKER       5
#define LSM_LOCK_CHECKPOINTER 6
#define LSM_LOCK_ROTRANS      7
#define LSM_LOCK_READER(i)    ((i) + LSM_LOCK_ROTRANS + 1)
#define LSM_LOCK_RWCLIENT(i)  ((i) + LSM_LOCK_READER(LSM_LOCK_NREADER))

/*
** Hard limit on the number of free-list entries that may be stored in 
** a checkpoint (the remainder are stored as a system record in the LSM).
** See also LSM_CONFIG_MAX_FREELIST.
*/

  u32 nWrite;                     /* Total number of pages written to disk */
};
#define LSM_INITIAL_SNAPSHOT_ID 11

/*
** Functions from file "lsm_ckpt.c".
*/
int lsmCheckpointWrite(lsm_db *, int, u32 *);
int lsmCheckpointLevels(lsm_db *, int, void **, int *);
int lsmCheckpointLoadLevels(lsm_db *pDb, void *pVal, int nVal);

int lsmCheckpointRecover(lsm_db *);
int lsmCheckpointDeserialize(lsm_db *, int, u32 *, Snapshot **);

int lsmCheckpointLoadWorker(lsm_db *pDb);

int lsmDbDatabaseConnect(lsm_db*, const char *);
void lsmDbDatabaseRelease(lsm_db *);

int lsmBeginReadTrans(lsm_db *);
int lsmBeginWriteTrans(lsm_db *);
int lsmBeginFlush(lsm_db *);

int lsmDetectRoTrans(lsm_db *db, int *);

int lsmBeginWork(lsm_db *);
void lsmFinishWork(lsm_db *, int, int *);

int lsmFinishRecovery(lsm_db *);
void lsmFinishReadTrans(lsm_db *);
int lsmFinishWriteTrans(lsm_db *, int);
int lsmFinishFlush(lsm_db *, int);

/* Candidate values for the 3rd argument to lsmShmLock() */
#define LSM_LOCK_UNLOCK 0
#define LSM_LOCK_SHARED 1
#define LSM_LOCK_EXCL   2

int lsmShmCacheChunks(lsm_db *db, int nChunk);
int lsmShmLock(lsm_db *db, int iLock, int eOp, int bBlock);
int lsmShmTestLock(lsm_db *db, int iLock, int nLock, int eOp);
void lsmShmBarrier(lsm_db *db);

#ifdef LSM_DEBUG
void lsmShmHasLock(lsm_db *db, int iLock, int eOp);
#else
# define lsmShmHasLock(x,y,z)
#endif

/*
** If possible, reclaim log file space. Log file space is reclaimed after
** a snapshot that points to the same data in the database file is synced
** into the db header.
*/
static int logReclaimSpace(lsm_db *pDb){
  int rc;
  int iMeta;
  int bRotrans;                   /* True if there exists some ro-trans */

  /* Test if there exists some other connection with a read-only transaction
  ** open. If there does, then log file space may not be reclaimed.  */
  rc = lsmDetectRoTrans(pDb, &bRotrans);
  if( rc!=LSM_OK || bRotrans ) return rc;

  iMeta = (int)pDb->pShmhdr->iMetaPage;
  if( iMeta==1 || iMeta==2 ){
    DbLog *pLog = &pDb->treehdr.log;
    i64 iSyncedId;

    /* Read the snapshot-id of the snapshot stored on meta-page iMeta. Note

            bReadonly = 1;
            rc = LSM_OK;
          }
        }

        /* Write a checkpoint to disk. */
        if( rc==LSM_OK ){
          rc = lsmCheckpointWrite(pDb, (bReadonly==0), 0);
        }

        /* If the checkpoint was written successfully, delete the log file
        ** and, if possible, truncate the database file.  */
        if( rc==LSM_OK ){
          int bRotrans = 0;
          Database *p = pDb->pDatabase;

          /* The log file may only be deleted if there are no clients 
          ** read-only clients running rotrans transactions.  */
          rc = lsmDetectRoTrans(pDb, &bRotrans);
          if( rc==LSM_OK && bRotrans==0 ){
            lsmFsCloseAndDeleteLog(pDb->pFS);
          }

          /* The database may only be truncated if there exist no read-only
          ** clients - either connected or running rotrans transactions. */
          if( bReadonly==0 && bRotrans==0 ){
            dbTruncateFile(pDb);
            if( p->pFile && p->bMultiProc ){
              lsmEnvShmUnmap(pDb->pEnv, p->pFile, 1);
            }
          }
        }
      }

    lsmLogMessage(pDb, 0, "lsmBlockAllocate(): "
        "snapshot-in-use: %lld (iSynced=%lld) (client-id=%lld)", 
        iInUse, iSynced, (pDb->iReader>=0 ? pDb->pClient->iId : 0)
    );
  }
#endif


  /* Unless there exists a read-only transaction (which prevents us from
  ** recycling any blocks regardless, query the free block list for a 
  ** suitable block to reuse. 
  **
  ** It might seem more natural to check for a read-only transaction at
  ** the start of this function. However, it is better do wait until after
  ** the call to lsmCheckpointSynced() to do so.
  */
  if( rc==LSM_OK ){
    int bRotrans;
    rc = lsmDetectRoTrans(pDb, &bRotrans);

    if( rc==LSM_OK && bRotrans==0 ){
      rc = findFreeblock(pDb, iInUse, (iBefore>0), &iRet);
    }
  }

  if( iBefore>0 && (iRet<=0 || iRet>=iBefore) ){
    iRet = 0;

  }else if( rc==LSM_OK ){
    /* If a block was found in the free block list, use it and remove it from 
    ** the list. Otherwise, if no suitable block was found, allocate one from

** database itself.
**
** The WORKER lock must not be held when this is called. This is because
** this function may indirectly call fsync(). And the WORKER lock should
** not be held that long (in case it is required by a client flushing an
** in-memory tree to disk).
*/
int lsmCheckpointWrite(lsm_db *pDb, int bTruncate, u32 *pnWrite){
  int rc;                         /* Return Code */
  u32 nWrite = 0;

  assert( pDb->pWorker==0 );
  assert( 1 || pDb->pClient==0 );
  assert( lsmShmAssertLock(pDb, LSM_LOCK_WORKER, LSM_LOCK_UNLOCK) );

      );
#endif
    }

    if( rc==LSM_OK && bTruncate ){
      rc = lsmFsTruncateDb(pDb->pFS, (i64)nBlock*lsmFsBlockSize(pDb->pFS));
    }



  }

  lsmShmLock(pDb, LSM_LOCK_CHECKPOINTER, LSM_LOCK_UNLOCK, 0);
  if( pnWrite && rc==LSM_OK ) *pnWrite = nWrite;
  return rc;
}

  }
  if( rc!=LSM_OK ){
    dbReleaseReadlock(pDb);
  }
  if( pDb->pClient==0 && rc==LSM_OK ) rc = LSM_BUSY;
  return rc;
}

/*
** This function is used by a read-write connection to determine if there
** are currently one or more read-only transactions open on the database
** (in this context a read-only transaction is one opened by a read-only
** connection on a non-live database).
**
** If no error occurs, LSM_OK is returned and *pbExists is set to true if
** some other connection has a read-only transaction open, or false 
** otherwise. If an error occurs an LSM error code is returned and the final
** value of *pbExist is undefined.
*/
int lsmDetectRoTrans(lsm_db *db, int *pbExist){
  int rc;

  /* Only a read-write connection may use this function. */
  assert( db->bReadonly==0 );

  rc = lsmShmTestLock(db, LSM_LOCK_ROTRANS, 1, LSM_LOCK_EXCL);
  if( rc==LSM_BUSY ){
    *pbExist = 1;
    rc = LSM_OK;
  }else{
    *pbExist = 0;
  }

  return rc;
}

/*
** db is a read-only database handle in the disconnected state. This function
** attempts to open a read-transaction on the database. This may involve
** connecting to the database system (opening shared memory etc.).
*/
int lsmBeginRoTrans(lsm_db *db){

    rc = lsmShmLock(db, LSM_LOCK_DMS1, LSM_LOCK_SHARED, 0);
    if( rc!=LSM_OK ) return rc;

    rc = lsmShmTestLock(
        db, LSM_LOCK_RWCLIENT(0), LSM_LOCK_NREADER, LSM_LOCK_SHARED
    );
    if( rc==LSM_OK ){
      /* System is not live. Take a SHARED lock on the ROTRANS byte and
      ** release DMS1. Locking ROTRANS tells all read-write clients that they
      ** may not recycle any disk space from within the database or log files,
      ** as a read-only client may be using it.  */
      rc = lsmShmLock(db, LSM_LOCK_ROTRANS, LSM_LOCK_SHARED, 0);
      lsmShmLock(db, LSM_LOCK_DMS1, LSM_LOCK_UNLOCK, 0);

      if( rc==LSM_OK ){
        db->bRoTrans = 1;
        rc = lsmShmCacheChunks(db, 1);
        if( rc==LSM_OK ){
          db->pShmhdr = (ShmHeader *)db->apShm[0];

      lsmFree(pDb->pEnv, pDb->apShm[i]);
    }
    lsmFree(pDb->pEnv, pDb->apShm);
    pDb->apShm = 0;
    pDb->nShm = 0;
    pDb->pShmhdr = 0;

    lsmShmLock(pDb, LSM_LOCK_ROTRANS, LSM_LOCK_UNLOCK, 0);
  }
  dbReleaseReadlock(pDb);
}

/*
** Open a write transaction.
*/

int lsm_checkpoint(lsm_db *pDb, int *pnKB){
  int rc;                         /* Return code */
  u32 nWrite = 0;                 /* Number of pages checkpointed */

  /* Attempt the checkpoint. If successful, nWrite is set to the number of
  ** pages written between this and the previous checkpoint.  */
  rc = lsmCheckpointWrite(pDb, 0, &nWrite);

  /* If required, calculate the output variable (KB of data checkpointed). 
  ** Set it to zero if an error occured.  */
  if( pnKB ){
    int nKB = 0;
    if( rc==LSM_OK && nWrite ){
      nKB = (((i64)nWrite * lsmFsPageSize(pDb->pFS)) + 1023) / 1024;

** is initialized here - it will be copied into shared memory if log file
** recovery is successful.
*/
int lsmTreeInit(lsm_db *pDb){
  ShmChunk *pOne;
  int rc = LSM_OK;

  memset(&pDb->treehdr, 0, sizeof(TreeHeader));
  pDb->treehdr.root.iTransId = 1;
  pDb->treehdr.iFirst = 1;
  pDb->treehdr.nChunk = 2;
  pDb->treehdr.iWrite = LSM_SHM_CHUNK_SIZE + LSM_SHM_CHUNK_HDR;
  pDb->treehdr.iNextShmid = 2;
  pDb->treehdr.iUsedShmid = 1;

  db info compression_id
} $compression_id(rle)

do_test 2.7 {
  db config {set_compression rle}
  list [db_fetch db 3] [db_fetch db 4]
} {three four}

#-------------------------------------------------------------------------
#
catch {db close}
forcedelete test.db

do_test 3.1 {
  lsm_open db test.db
  db_fetch db abc
} {}

finish_test

  set ret
}

# Create a new database with file name $file.
#
proc create_abc_db {file} {
  forcedelete $file
  lsm_open db $file {block_size 256}
  db write a alpha
  db write b bravo
  db write c charlie
  db close
}

proc create_abc_log {file} {

do_test 4.2 {
  lsm_open db test.db {readonly 1}
  db csr_open T
  list [db_fetch db a] [db_fetch db b] [db_fetch db c]
} {alpha bravo charlie}

do_test 4.3 { 
  lsm_open db_rw test.db {block_size 64}
  db_rw write b BRAVO
  db_rw close
  list [file size test.db] [file size test.db-log]
} {65536 74}

do_test 4.4 {
  list [db_fetch db a] [db_fetch db b] [db_fetch db c]
} {alpha bravo charlie}

do_test 4.5 {
  T close
  list [db_fetch db a] [db_fetch db b] [db_fetch db c]
} {alpha BRAVO charlie}

finish_test