Package db.buffers

Class DataBuffer

  • All Implemented Interfaces:
    Buffer, java.io.Externalizable, java.io.Serializable
    public class DataBuffer
extends java.lang.Object
implements Buffer, java.io.Externalizable
    DataBuffer provides an accessible binary buffer for use with a BufferMgr and BufferFile.
    See Also:
    Serialized Form

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
        DataBuffer()
      Constructor for de-serialization
      protected DataBuffer​(byte[] data)
      Construct a data buffer.
      protected DataBuffer​(int bufsize)
      Construct a data buffer.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Sets all the values in the buffer to 0;
      void copy​(int offset, DataBuffer buf, int bufOffset, int length)
      Copy data from another buffer into this buffer.
      static void enableCompressedSerializationOutput​(boolean enable)  
      void get​(int offset, byte[] bytes)
      Get the byte data located at the specified offset and store into the bytes array provided.
      void get​(int offset, byte[] bytes, int dataOffset, int length)
      Get the byte data located at the specified offset and store into the data array at the specified data offset.
      byte[] get​(int offset, int length)
      Get the byte data located at the specified offset.
      byte getByte​(int offset)
      Get the 8-bit byte value located at the specified offset.
      protected byte[] getData()
      Get the storage array associated with this buffer.
      int getId()
      Get the ID associated with this buffer.
      int getInt​(int offset)
      Get the 32-bit integer value located at the specified offset.
      long getLong​(int offset)
      Get the 64-bit long value located at the specified offset.
      short getShort​(int offset)
      Get the 16-bit short value located at the specified offset.
      boolean isDirty()
      Return true if this buffer contains modified data.
      boolean isEmpty()
      Return true if this buffer is empty/unused.
      int length()
      Get the length of the buffer in bytes.
      void move​(int src, int dest, int length)
      Move the data within this buffer.
      int put​(int offset, byte[] bytes)
      Put the bytes provided into the buffer at the specified offset.
      int put​(int offset, byte[] bytes, int dataOffset, int length)
      Put a specified number of bytes from the array provided into the buffer at the specified offset.
      int putByte​(int offset, byte b)
      Put the 8-bit byte value into the buffer at the specified offset.
      int putInt​(int offset, int v)
      Put the 32-bit integer value into the buffer at the specified offset.
      int putLong​(int offset, long v)
      Put the 64-bit long value into the buffer at the specified offset.
      int putShort​(int offset, short v)
      Put the 16-bit short value into the buffer at the specified offset.
      void readExternal​(java.io.ObjectInput in)  
      protected void setData​(byte[] data)
      Get the storage array associated with this buffer.
      protected void setDirty​(boolean state)
      Set the dirty flag.
      protected void setEmpty​(boolean state)
      Set the empty flag.
      protected void setId​(int id)
      Set the ID associated with this buffer.
      static boolean usingCompressedSerializationOutput()  
      void writeExternal​(java.io.ObjectOutput out)  

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • COMPRESSED_SERIAL_OUTPUT_PROPERTY

        public static final java.lang.String COMPRESSED_SERIAL_OUTPUT_PROPERTY
        See Also:
        Constant Field Values

      • data

        protected byte[] data

    • Constructor Detail

      • DataBuffer

        public DataBuffer()
        Constructor for de-serialization

      • DataBuffer

        protected DataBuffer​(int bufsize)
        Construct a data buffer. A new binary buffer is created.
        Parameters:
        bufsize - buffer size

      • DataBuffer

        protected DataBuffer​(byte[] data)
        Construct a data buffer.
        Parameters:
        data - binary storage array for this buffer.

    • Method Detail

      • enableCompressedSerializationOutput

        public static void enableCompressedSerializationOutput​(boolean enable)

      • usingCompressedSerializationOutput

        public static boolean usingCompressedSerializationOutput()

      • getData

        protected byte[] getData()
        Get the storage array associated with this buffer.
        Returns:
        byte storage array.

      • setData

        protected void setData​(byte[] data)
        Get the storage array associated with this buffer.

      • getId

        public int getId()
        Get the ID associated with this buffer.
        Specified by:
        getId in interface Buffer
        Returns:
        buffer ID.

      • setId

        protected void setId​(int id)
        Set the ID associated with this buffer.
        Parameters:
        id - buffer ID

      • isDirty

        public boolean isDirty()
        Return true if this buffer contains modified data. When this buffer is released to the BufferMgr, the data is consumed and this flag reset to false.

      • setDirty

        protected void setDirty​(boolean state)
        Set the dirty flag.
        Parameters:
        state - flag state.

      • isEmpty

        public boolean isEmpty()
        Return true if this buffer is empty/unused. Writing to empty buffer does not change the state of this flag.

      • setEmpty

        protected void setEmpty​(boolean state)
        Set the empty flag.
        Parameters:
        state - flag state

      • length

        public int length()
        Description copied from interface: Buffer
        Get the length of the buffer in bytes. The length reflects the number of bytes which have been allocated to the buffer.
        Specified by:
        length in interface Buffer
        Returns:
        length of allocated buffer.

      • get

        public void get​(int offset,
                byte[] bytes,
                int dataOffset,
                int length)
         throws java.lang.ArrayIndexOutOfBoundsException
        Description copied from interface: Buffer
        Get the byte data located at the specified offset and store into the data array at the specified data offset.
        Specified by:
        get in interface Buffer
        Parameters:
        offset - byte offset from the start of the buffer.
        bytes - byte array to store the data.
        dataOffset - offset into the data buffer
        length - amount of data to read
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - if an invalid offset, dataOffset, or length is specified.

      • get

        public void get​(int offset,
                byte[] bytes)
        Description copied from interface: Buffer
        Get the byte data located at the specified offset and store into the bytes array provided.
        Specified by:
        get in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        bytes - byte array to store data

      • get

        public byte[] get​(int offset,
                  int length)
           throws java.lang.ArrayIndexOutOfBoundsException
        Description copied from interface: Buffer
        Get the byte data located at the specified offset.
        Specified by:
        get in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        Returns:
        the byte array.
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - is thrown if an invalid offset is specified or the end of the buffer was encountered while reading the data.

      • getByte

        public byte getByte​(int offset)
        Description copied from interface: Buffer
        Get the 8-bit byte value located at the specified offset.
        Specified by:
        getByte in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        Returns:
        the byte value at the specified offset.

      • getInt

        public int getInt​(int offset)
        Description copied from interface: Buffer
        Get the 32-bit integer value located at the specified offset.
        Specified by:
        getInt in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        Returns:
        the integer value at the specified offset.

      • getShort

        public short getShort​(int offset)
        Description copied from interface: Buffer
        Get the 16-bit short value located at the specified offset.
        Specified by:
        getShort in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        Returns:
        the short value at the specified offset.

      • getLong

        public long getLong​(int offset)
        Description copied from interface: Buffer
        Get the 64-bit long value located at the specified offset.
        Specified by:
        getLong in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        Returns:
        the long value at the specified offset.

      • put

        public int put​(int offset,
               byte[] bytes,
               int dataOffset,
               int length)
        Description copied from interface: Buffer
        Put a specified number of bytes from the array provided into the buffer at the specified offset. The number of bytes stored is specified by the length specified.
        Specified by:
        put in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        bytes - the byte data to be stored.
        dataOffset - the starting offset into the data.
        length - the number of bytes to be stored.
        Returns:
        the next available offset into the buffer, or -1 if the buffer is full.

      • put

        public int put​(int offset,
               byte[] bytes)
        Description copied from interface: Buffer
        Put the bytes provided into the buffer at the specified offset. The number of bytes stored is determined by the length of the bytes array.
        Specified by:
        put in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        bytes - the byte data to be stored.
        Returns:
        the next available offset into the buffer, or -1 if the buffer is full.

      • putByte

        public int putByte​(int offset,
                   byte b)
        Description copied from interface: Buffer
        Put the 8-bit byte value into the buffer at the specified offset.
        Specified by:
        putByte in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        b - the byte value to be stored.
        Returns:
        the next available offset into the buffer, or -1 if the buffer is full.

      • putInt

        public int putInt​(int offset,
                  int v)
        Description copied from interface: Buffer
        Put the 32-bit integer value into the buffer at the specified offset.
        Specified by:
        putInt in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        v - the integer value to be stored.
        Returns:
        the next available offset into the buffer, or -1 if the buffer is full.

      • putShort

        public int putShort​(int offset,
                    short v)
        Description copied from interface: Buffer
        Put the 16-bit short value into the buffer at the specified offset.
        Specified by:
        putShort in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        v - the short value to be stored.
        Returns:
        the next available offset into the buffer, or -1 if the buffer is full.

      • putLong

        public int putLong​(int offset,
                   long v)
        Description copied from interface: Buffer
        Put the 64-bit long value into the buffer at the specified offset.
        Specified by:
        putLong in interface Buffer
        Parameters:
        offset - byte offset from start of buffer.
        v - the long value to be stored.
        Returns:
        the next available offset into the buffer, or -1 if the buffer is full.

      • clear

        public void clear()
        Sets all the values in the buffer to 0;

      • move

        public void move​(int src,
                 int dest,
                 int length)
        Move the data within this buffer.
        Parameters:
        src - source offset within this buffer
        dest - destination offset within this buffer
        length - length of data to be moved
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - is thrown if parameters result in data access beyond the buffer size.

      • copy

        public void copy​(int offset,
                 DataBuffer buf,
                 int bufOffset,
                 int length)
        Copy data from another buffer into this buffer.
        Parameters:
        offset - offset within this buffer.
        buf - source buffer
        bufOffset - source buffer offset
        length - amount of data to copy.
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - is thrown if parameters result in data access beyond the buffer size.

      • writeExternal

        public void writeExternal​(java.io.ObjectOutput out)
                   throws java.io.IOException
        Specified by:
        writeExternal in interface java.io.Externalizable
        Throws:
        java.io.IOException

      • readExternal

        public void readExternal​(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException
        Specified by:
        readExternal in interface java.io.Externalizable
        Throws:
        java.io.IOException
        java.lang.ClassNotFoundException