Package org.apache.derby.impl.jdbc

Class LOBStreamControl

  • final class LOBStreamControl
extends java.lang.Object
    This class acts as a layer of blob/clob repository (in memory or file). The max bytes of data stored in memory depends on the way this class is created. If the class is created with initial data, the buffer size is set to the size of the byte array supplied, but no larger than MAX_BUF_SIZE. If no initial data is supplied, or if the initial data size is less than DEFAULT_BUF_SIZE, the buffer size is set to DEFAULT_BUF_SIZE. When write increases the data beyond this value a temporary file is created and data is moved into that. If truncate reduces the size of the file below initial buffer size, the data is moved into memory. This class also creates InputStream and OutputStream which can be used to access blob data irrespective of if its in memory or in file.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) void copyData​(java.io.InputStream inStream, long length)
      Copies bytes from stream to local storage.
      (package private) long copyUtf8Data​(java.io.InputStream utf8Stream, long charLength)
      Copies UTF-8 encoded chars from a stream to local storage.
      private void deleteFile​(StorageFile file)  
      protected void finalize()  
      private static java.lang.Object findService​(java.lang.String factoryInterface, java.lang.String serviceName)
      Privileged service lookup.
      private static java.lang.Object findServiceModule​(java.lang.Object serviceModule, java.lang.String factoryInterface)
      Privileged startup.
      (package private) void free()
      Invalidates all the variables and closes file handle if open.
      (package private) java.io.InputStream getInputStream​(long pos)
      returns input stream linked with this object.
      (package private) long getLength()
      Returns length of data.
      (package private) java.io.OutputStream getOutputStream​(long pos)
      returns output stream linked with this object
      (package private) long getUpdateCount()
      Returns the running sequence number to check if the lob is updated since last access.
      private void init​(byte[] b, long len)  
      private void isValidOffset​(int off, int length)  
      private void isValidPostion​(long pos)  
      (package private) int read​(byte[] buff, int off, int len, long pos)
      Reads bytes starting from 'position' into bytes array.
      (package private) int read​(long pos)
      Reads one byte.
      private int readBytes​(byte[] b, int off, int len, long pos)  
      private void releaseTempFile​(LOBFile file)
      Close and release all resources held by a temporary file.
      (package private) long replaceBytes​(byte[] buf, long stPos, long endPos)
      Replaces a block of bytes in the middle of the LOB with a another block of bytes, which may be of a different size.
      (package private) void truncate​(long size)
      Resets the size.
      private long updateData​(byte[] bytes, int offset, int len, long pos)  
      (package private) long write​(byte[] b, int off, int len, long pos)
      Writes len bytes from the specified byte array to the LOB.
      (package private) long write​(int b, long pos)
      Writes one byte.

      • Methods inherited from class java.lang.Object

        clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • dataBytes

        private byte[] dataBytes

      • isBytes

        private boolean isBytes

      • bufferSize

        private final int bufferSize

      • updateCount

        private long updateCount

    • Constructor Detail

      • LOBStreamControl

        LOBStreamControl​(EmbedConnection conn)
        Creates an empty LOBStreamControl.
        Parameters:
        conn - Connection for this lob

      • LOBStreamControl

        LOBStreamControl​(EmbedConnection conn,
                 byte[] data)
          throws java.io.IOException,
                 StandardException
        Creates a LOBStreamControl and initializes with a bytes array.
        Parameters:
        conn - Connection for this lob
        data - initial value
        Throws:
        java.io.IOException
        StandardException

    • Method Detail

      • write

        long write​(int b,
           long pos)
    throws java.io.IOException,
           StandardException
        Writes one byte.
        Parameters:
        b - byte
        pos -
        Returns:
        new position
        Throws:
        java.io.IOException - if writing to the LOB file fails
        StandardException - if encrypting/decrypting the LOB file fails

      • write

        long write​(byte[] b,
           int off,
           int len,
           long pos)
    throws java.io.IOException,
           StandardException
        Writes len bytes from the specified byte array to the LOB.
        Parameters:
        b - byte array
        off - offset from where to read from the byte array
        len - number of bytes to be written
        pos - starting position
        Returns:
        The position after the bytes have been written to the LOB.
        Throws:
        java.io.IOException - if writing to the LOB fails
        StandardException - if writing to the LOB fails
        java.lang.IndexOutOfBoundsException - if len is larger than b.length - off

      • read

        int read​(long pos)
  throws java.io.IOException,
         StandardException
        Reads one byte.
        Parameters:
        pos - position from where to read
        Returns:
        byte
        Throws:
        java.io.IOException - if reading the LOB file fails
        StandardException - if decrypting an encrypted LOB file fails

      • readBytes

        private int readBytes​(byte[] b,
                      int off,
                      int len,
                      long pos)

      • read

        int read​(byte[] buff,
         int off,
         int len,
         long pos)
  throws java.io.IOException,
         StandardException
        Reads bytes starting from 'position' into bytes array. starting from 'offset'
        Parameters:
        buff - array into the bytes will be copied
        off - offset from where the array has to be populated
        len - number of bytes to read
        pos - initial position before reading
        Returns:
        number new position
        Throws:
        java.io.IOException - if reading the LOB file fails
        StandardException - if decrypting an encrypted LOB file fails

      • getInputStream

        java.io.InputStream getInputStream​(long pos)
        returns input stream linked with this object.
        Parameters:
        pos - initial postion
        Returns:
        InputStream

      • getOutputStream

        java.io.OutputStream getOutputStream​(long pos)
        returns output stream linked with this object
        Parameters:
        pos - initial postion
        Returns:
        OutputStream

      • getLength

        long getLength()
        throws java.io.IOException
        Returns length of data.
        Returns:
        length
        Throws:
        java.io.IOException

      • truncate

        void truncate​(long size)
       throws java.io.IOException,
              StandardException
        Resets the size.
        Parameters:
        size - new size should be smaller than existing size
        Throws:
        java.io.IOException
        StandardException

      • copyData

        void copyData​(java.io.InputStream inStream,
              long length)
       throws java.io.IOException,
              StandardException
        Copies bytes from stream to local storage.

        Note that specifying the length as Long.MAX_VALUE results in reading data from the stream until EOF is reached, but no length checking will be performed.

        Parameters:
        inStream - the stream to copy from
        length - number of bytes to be copied, or Long.MAX_VALUE to copy everything until EOF is reached
        Throws:
        java.io.IOException - if reading or writing a LOB file fails
        StandardException - if encrypting or decrypting a LOB file fails

      • copyUtf8Data

        long copyUtf8Data​(java.io.InputStream utf8Stream,
                  long charLength)
           throws java.io.IOException,
                  StandardException
        Copies UTF-8 encoded chars from a stream to local storage.

        Note that specifying the length as Long.MAX_VALUE results in reading data from the stream until EOF is reached, but no length checking will be performed.

        Parameters:
        utf8Stream - the stream to copy from
        charLength - number of chars to be copied, or Long.MAX_VALUE to copy everything until EOF is reached
        Returns:
        The number of characters copied.
        Throws:
        java.io.EOFException - if EOF is reached prematurely
        java.io.IOException - thrown on a number of error conditions
        StandardException - if reading, writing or truncating the LOBStreamControl-object fails
        java.io.UTFDataFormatException - if an invalid UTF-8 encoding is detected

      • finalize

        protected void finalize()
                 throws java.lang.Throwable
        Overrides:
        finalize in class java.lang.Object
        Throws:
        java.lang.Throwable

      • deleteFile

        private void deleteFile​(StorageFile file)

      • free

        void free()
   throws java.io.IOException
        Invalidates all the variables and closes file handle if open.
        Throws:
        java.io.IOException - if closing the file fails

      • releaseTempFile

        private void releaseTempFile​(LOBFile file)
                      throws java.io.IOException
        Close and release all resources held by a temporary file. The file will also be deleted from the file system and removed from the list of LOBFiles in EmbedConnection.
        Parameters:
        file - the temporary file
        Throws:
        java.io.IOException - if the file cannot be closed or deleted

      • replaceBytes

        long replaceBytes​(byte[] buf,
                  long stPos,
                  long endPos)
           throws java.io.IOException,
                  StandardException
        Replaces a block of bytes in the middle of the LOB with a another block of bytes, which may be of a different size.

        The new byte array may not be be of same length as the original, thus it may result in resizing the total lob.

        Parameters:
        buf - byte array which will be written inplace of old block
        stPos - inclusive starting position of current block
        endPos - exclusive end position of current block
        Returns:
        Current position after write.
        Throws:
        java.io.IOException - if writing to the temporary file fails
        StandardException

      • getUpdateCount

        long getUpdateCount()
        Returns the running sequence number to check if the lob is updated since last access.
        Returns:
        The current update sequence number.

      • findServiceModule

        private static java.lang.Object findServiceModule​(java.lang.Object serviceModule,
                                                  java.lang.String factoryInterface)
                                           throws StandardException
        Privileged startup. Must be private so that user code can't call this entry point.
        Throws:
        StandardException

      • findService

        private static java.lang.Object findService​(java.lang.String factoryInterface,
                                            java.lang.String serviceName)
        Privileged service lookup. Must be private so that user code can't call this entry point.