Interface ISqlJetFile

  • All Known Implementing Classes:
    SqlJetFile, SqlJetMemJournal

    public interface ISqlJetFile
    OS Interface Open File Handle. An ISqlJetFile object represents an open file in the OS interface layer. Individual OS interface implementations will want to subclass this object by appending additional fields for their own use.
    • Method Detail

      • sync

        void sync​(java.util.Set<SqlJetSyncFlags> syncFlags)
           throws SqlJetIOException
        Make sure all writes to a particular file are committed to disk. If dataOnly==false then both the file itself and its metadata (file size, access time, etc) are synced. If dataOnly==true then only the file data is synced. Also make sure that the directory entry for the file has been created by fsync-ing the directory that contains the file. If we do not do this and we encounter a power failure, the directory entry for the journal might not exist after we reboot. The next SqlJet to access the file will not know that the journal exists (because the directory entry for the journal was never created) and the transaction will not roll back - possibly leading to database corruption.
        Parameters:
        dataOnly -
        full -
        Throws:
        SqlJetIOException
      • lock

        boolean lock​(SqlJetLockType lockType)
              throws SqlJetIOException
        Lock the file with the lock specified by parameter locktype - one of the following: (1) SHARED (2) RESERVED (3) PENDING (4) EXCLUSIVE Sometimes when requesting one lock state, additional lock states are inserted in between. The locking might fail on one of the later transitions leaving the lock state different from what it started but still short of its goal. The following chart shows the allowed transitions and the inserted intermediate states: UNLOCKED -> SHARED SHARED -> RESERVED SHARED -> (PENDING) -> EXCLUSIVE RESERVED -> (PENDING) -> EXCLUSIVE PENDING -> EXCLUSIVE This routine will only increase a lock.
        Parameters:
        lockType -
        Returns:
        Throws:
        SqlJetIOException
      • unlock

        boolean unlock​(SqlJetLockType lockType)
                throws SqlJetIOException
        Lower the locking level on file descriptor pFile to locktype. locktype must be either NONE or SHARED. If the locking level of the file descriptor is already at or below the requested locking level, this routine is a no-op.
        Parameters:
        lockType -
        Returns:
        Throws:
        SqlJetIOException
      • checkReservedLock

        boolean checkReservedLock()
        This routine checks if there is a RESERVED lock held on the specified file by this or any other process. The return value is set unless an I/O error occurs during lock checking.
        Returns:
      • getLockType

        SqlJetLockType getLockType()
        Returns lock type of file.
        Returns:
      • sectorSize

        int sectorSize()
        Return the sector size in bytes of the underlying block device for the specified file. This is almost always 512 bytes, but may be larger for some devices. SqlJet code assumes this function cannot fail. It also assumes that if two files are created in the same file-system directory (i.e. a database and its journal file) that the sector size will be the same for both.
        Returns:
      • deviceCharacteristics

        java.util.Set<SqlJetDeviceCharacteristics> deviceCharacteristics()
        Return the device characteristics for the file.
        Returns:
      • isMemJournal

        boolean isMemJournal()
        Return true if the file-handle passed as an argument is an in-memory journal