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Oracle® Coherence Java API Reference
Release 3.7.0.0

E18683-01


com.tangosol.io
Class DelegatingWriteBuffer

java.lang.Object
  extended by com.tangosol.io.AbstractWriteBuffer
      extended by com.tangosol.io.DelegatingWriteBuffer

All Implemented Interfaces:
WriteBuffer

public final class DelegatingWriteBuffer
extends AbstractWriteBuffer

A DelegatingWriteBuffer is a WriteBuffer that writes through to an underlying (or "containing") WriteBuffer. Basically, it allows a process that is writing to a WriteBuffer to ask for a "protected" sub-portion of that WriteBuffer to hand to a second process, such that the second process can not affect (or even read from) the WriteBuffer outside of the portion that the first process explicitly designated as viewable and modifiable.

This implementation is explicitly not thread-safe.

Author:
cp 2005.03.24 created

Nested Class Summary
 class DelegatingWriteBuffer.DelegatingBufferOutput
          A BufferOutput implementation that delegates to a BufferOutput implementation, except that its offset range is shifted and limited.

 

Nested classes/interfaces inherited from class com.tangosol.io.AbstractWriteBuffer
AbstractWriteBuffer.AbstractBufferOutput

 

Nested classes/interfaces inherited from interface com.tangosol.io.WriteBuffer
WriteBuffer.BufferOutput

 

Field Summary
protected  WriteBuffer m_buf
          The WriteBuffer to delegate to; the "containing" WriteBuffer.
protected  int m_cb
          Length in bytes of this WriteBuffer.
protected  int m_cbMax
          Maximum number of bytes in this WriteBuffer.
protected  int m_ofStart
          Offset into the containing WriteBuffer where this WriteBuffer starts.

 

Fields inherited from class com.tangosol.io.AbstractWriteBuffer
CHAR_BUF_MASK, CHAR_BUF_SIZE, m_achBuf, NO_BINARY, NO_BYTES

 

Constructor Summary
DelegatingWriteBuffer(WriteBuffer buf, int of, int cb)
          Construct a DelegatingWriteBuffer that will delegate to the containing WriteBuffer.

 

Method Summary
protected  void checkBounds(int of, int cb)
          Test an offset and length of data to write to see if it can be written to this buffer.
 void clear()
          Set the length of the buffer as indicated by the WriteBuffer.length() method to zero.
protected  int copyStream(int ofDest, InputStreaming stream, int cbMax)
          Store the remaining contents of the specified InputStreaming object at the specified offset within this buffer.
 WriteBuffer.BufferOutput getBufferOutput(int of)
          Get a BufferOutput object to write data to this buffer starting at a particular offset.
 int getCapacity()
          Determine the number of bytes that the buffer can hold without resizing itself.
 int getMaximumCapacity()
          Determine the maximum number of bytes that the buffer can hold.
 ReadBuffer getReadBuffer()
          Get a ReadBuffer object that is a snapshot of this WriteBuffer's data.
 ReadBuffer getUnsafeReadBuffer()
          Get a ReadBuffer object to read data from this buffer.
 int length()
          Determine the length of the data that is in the buffer.
 void retain(int of, int cb)
          Starting with the byte at offset of, retain cb bytes in this WriteBuffer, such that the byte at offset of is shifted to offset 0, the byte at offset of + 1 is shifted to offset 1, and so on up to the byte at offset of + cb - 1, which is shifted to offset cb - 1.
 Binary toBinary()
          Returns a new Binary object that holds the complete contents of this WriteBuffer.
 byte[] toByteArray()
          Returns a new byte array that holds the complete contents of this WriteBuffer.
protected  void updateLength(int cb)
          Update the length if the passed length is greater than the current buffer length.
 void write(int ofDest, byte b)
          Store the specified byte at the specified offset within the buffer.
 void write(int ofDest, byte[] abSrc, int ofSrc, int cbSrc)
          Store the specified number of bytes from the specified location within the passed byte array at the specified offset within this buffer.
 void write(int ofDest, InputStreaming stream)
          Store the remaining contents of the specified InputStreaming object at the specified offset within this buffer.
 void write(int ofDest, InputStreaming stream, int cbSrc)
          Store the specified number of bytes from the specified InputStreaming object at the specified offset within this buffer.
 void write(int ofDest, ReadBuffer bufSrc, int ofSrc, int cbSrc)
          Store the specified portion of the contents of the specified ReadBuffer at the specified offset within this buffer.

 

Methods inherited from class com.tangosol.io.AbstractWriteBuffer
clone, copyBufferInputPortion, copyBufferInputRemainder, getAppendingBufferOutput, getBufferOutput, getWriteBuffer, getWriteBuffer, releaseBuffers, retain, tmpbuf, tmpbuf, write, write

 

Field Detail

m_buf

protected WriteBuffer m_buf
The WriteBuffer to delegate to; the "containing" WriteBuffer.

m_ofStart

protected int m_ofStart
Offset into the containing WriteBuffer where this WriteBuffer starts.

m_cb

protected int m_cb
Length in bytes of this WriteBuffer.

m_cbMax

protected int m_cbMax
Maximum number of bytes in this WriteBuffer.

Constructor Detail

DelegatingWriteBuffer

public DelegatingWriteBuffer(WriteBuffer buf,
                             int of,
                             int cb)
Construct a DelegatingWriteBuffer that will delegate to the containing WriteBuffer.
Parameters:
buf - the containing WriteBuffer
of - the offset within the containing WriteBuffer that this WriteBuffer is starting at
cb - the maximum capacity for this WriteBuffer

Method Detail

write

public void write(int ofDest,
                  byte b)
Store the specified byte at the specified offset within the buffer.

For purposes of side-effects and potential exceptions, this method is functionally equivalent to the following code:


 byte[] abSrc = new byte[1];
 abSrc[0] = b;
 write(ofDest, abSrc, 0, abSrc.length);
 
Specified by:
write in interface WriteBuffer
Specified by:
write in class AbstractWriteBuffer
Parameters:
ofDest - the offset within this buffer to store the passed data
b - the byte to store in this buffer

write

public void write(int ofDest,
                  byte[] abSrc,
                  int ofSrc,
                  int cbSrc)
Store the specified number of bytes from the specified location within the passed byte array at the specified offset within this buffer.

As a result of this method, the buffer length as reported by the WriteBuffer.length() method will become Math.max(WriteBuffer.length(), ofDest + cbSrc).

As a result of this method, the buffer capacity as reported by the WriteBuffer.getCapacity() method will not change if the new value returned by WriteBuffer.length() would not exceed the old value returned by WriteBuffer.getCapacity(); otherwise, the capacity will be increased such that WriteBuffer.getCapacity() >= WriteBuffer.length(). Regardless, it is always true that WriteBuffer.getCapacity() >= WriteBuffer.length() and WriteBuffer.getMaximumCapacity() >= WriteBuffer.getCapacity(). If the buffer capacity cannot be increased due to resource constraints, an undesignated Error or RuntimeException will be thrown, such as OutOfMemoryError.

Specified by:
write in interface WriteBuffer
Specified by:
write in class AbstractWriteBuffer
Parameters:
ofDest - the offset within this buffer to store the passed data
abSrc - the array containing the bytes to store in this buffer
ofSrc - the offset within the passed byte array to copy from
cbSrc - the number of bytes to copy from the passed byte array

write

public void write(int ofDest,
                  ReadBuffer bufSrc,
                  int ofSrc,
                  int cbSrc)
Store the specified portion of the contents of the specified ReadBuffer at the specified offset within this buffer.

For purposes of side-effects and potential exceptions, this method is functionally equivalent to the following code:


 byte[] abSrc = bufSrc.toByteArray(ofSrc, cbSrc);
 write(ofDest, abSrc, 0, abSrc.length);
 
Specified by:
write in interface WriteBuffer
Overrides:
write in class AbstractWriteBuffer
Parameters:
ofDest - the offset within this buffer to store the passed data
bufSrc - the array of bytes to store in this buffer
ofSrc - the offset within the passed ReadBuffer to copy from
cbSrc - the number of bytes to copy from the passed ReadBuffer

write

public void write(int ofDest,
                  InputStreaming stream)
           throws java.io.IOException
Store the remaining contents of the specified InputStreaming object at the specified offset within this buffer.

For purposes of side-effects and potential exceptions, this method is functionally similar to the following code:


 ByteArrayOutputStream streamOut = new ByteArrayOutputStream();
 int b;
 while ((b = stream.read()) >= 0)
     {
     streamOut.write(b);
     }
 byte[] abSrc = streamOut.toByteArray();
 write(ofDest, abSrc, 0, abSrc.length);
 
Specified by:
write in interface WriteBuffer
Overrides:
write in class AbstractWriteBuffer
Parameters:
ofDest - the offset within this buffer to store the passed data
stream - the stream of bytes to read and store in this buffer
Throws:
java.io.IOException - if an IOException occurs reading from the passed stream

write

public void write(int ofDest,
                  InputStreaming stream,
                  int cbSrc)
           throws java.io.IOException
Store the specified number of bytes from the specified InputStreaming object at the specified offset within this buffer.

For purposes of side-effects and potential exceptions, this method is functionally similar to the following code:


 DataInputStream streamData = new DataInputStream(
         new WrapperInputStream(stream));
 byte[] abSrc = new byte[cbSrc];
 streamData.readFully(abSrc);
 write(ofDest, abSrc, 0, abSrc.length);
 
Specified by:
write in interface WriteBuffer
Overrides:
write in class AbstractWriteBuffer
Parameters:
ofDest - the offset within this buffer to store the passed data
stream - the stream of bytes to read and store in this buffer
cbSrc - the exact number of bytes to read from the stream and put in this buffer
Throws:
java.io.IOException - if an IOException occurs reading from the passed stream

length

public int length()
Determine the length of the data that is in the buffer. This is the actual number of bytes of data that have been written to the buffer, not the capacity of the buffer.
Specified by:
length in interface WriteBuffer
Specified by:
length in class AbstractWriteBuffer
Returns:
the number of bytes of data represented by this WriteBuffer

retain

public void retain(int of,
                   int cb)
Starting with the byte at offset of, retain cb bytes in this WriteBuffer, such that the byte at offset of is shifted to offset 0, the byte at offset of + 1 is shifted to offset 1, and so on up to the byte at offset of + cb - 1, which is shifted to offset cb - 1. After this method, the length of the buffer as indicated by the WriteBuffer.length() method will be equal to cb.

Legal values for the offset of the first byte to retain of are (of >= 0 && of <= WriteBuffer.length()). Legal values for the number of bytes to retain cb are (cb >= 0 && cb <= WriteBuffer.length()), such that (of + cb <= WriteBuffer.length()).

If cb is zero, then this method will have the same effect as clear. If of is zero, then this method will have the effect of truncating the data in the buffer, but no bytes will be shifted within the buffer.

The effect on the capacity of the buffer is implementation-specific; some implementations are expected to retain the same capacity while others are expected to shrink accordingly.

Specified by:
retain in interface WriteBuffer
Specified by:
retain in class AbstractWriteBuffer
Parameters:
of - the offset of the first byte within the WriteBuffer that will be retained
cb - the number of bytes to retain

clear

public void clear()
Set the length of the buffer as indicated by the WriteBuffer.length() method to zero.

The effect on the capacity of the buffer is implementation-specific; some implementations are expected to retain the same capacity while others are expected to shrink accordingly.

Specified by:
clear in interface WriteBuffer
Overrides:
clear in class AbstractWriteBuffer

getCapacity

public int getCapacity()
Determine the number of bytes that the buffer can hold without resizing itself. In other words, a WriteBuffer has getCapacity() - WriteBuffer.length() bytes that can be written to it without overflowing the current underlying buffer allocation. Since the buffer is an abstract concept, the actual mechanism for the underlying buffer is not known, but it could be a Java NIO buffer, or a byte array, etc.

Note that if the maximum size returned by WriteBuffer.getMaximumCapacity() is greater than the current size returned by this method, then the WriteBuffer will automatically resize itself to allocate more space when the amount of data written to it passes the current size.

Specified by:
getCapacity in interface WriteBuffer
Specified by:
getCapacity in class AbstractWriteBuffer
Returns:
the number of bytes of data that this WriteBuffer can hold without resizing its underlying buffer

getMaximumCapacity

public int getMaximumCapacity()
Determine the maximum number of bytes that the buffer can hold. If the maximum size is greater than the current size, then the buffer is expected to resize itself as necessary up to the maximum size in order to contain the data given to it.
Specified by:
getMaximumCapacity in interface WriteBuffer
Overrides:
getMaximumCapacity in class AbstractWriteBuffer
Returns:
the maximum number of bytes of data that the WriteBuffer can hold

getBufferOutput

public WriteBuffer.BufferOutput getBufferOutput(int of)
Get a BufferOutput object to write data to this buffer starting at a particular offset.

Note that each call to this method will return a new BufferOutput object, with the possible exception being that a zero-length non-resizing WriteBuffer could always return the same instance (since it is not writable).

This is functionally equivalent to:


 BufferOutput bufout = getBufferOutput();
 bufout.setOffset(of);
 return bufout;
 
Specified by:
getBufferOutput in interface WriteBuffer
Overrides:
getBufferOutput in class AbstractWriteBuffer
Parameters:
of - the offset of the first byte of this buffer that the BufferOutput will write to
Returns:
a BufferOutput that will write to this buffer

getReadBuffer

public ReadBuffer getReadBuffer()
Get a ReadBuffer object that is a snapshot of this WriteBuffer's data.

This method is functionally equivalent to the following code:


 ReadBuffer buf = getUnsafeReadBuffer();
 byte[] ab = buf.toByteArray();
 return new ByteArrayReadBuffer(ab);
 
Specified by:
getReadBuffer in interface WriteBuffer
Overrides:
getReadBuffer in class AbstractWriteBuffer
Returns:
a ReadBuffer that reflects the point-in-time contents of this WriteBuffer

getUnsafeReadBuffer

public ReadBuffer getUnsafeReadBuffer()
Get a ReadBuffer object to read data from this buffer. This method is not guaranteed to return a snapshot of this buffer's data, nor is it guaranteed to return a live view of this buffer, which means that subsequent changes to this WriteBuffer may or may not affect the contents and / or the length of the returned ReadBuffer.

To get a snapshot, use the WriteBuffer.getReadBuffer() method.

Specified by:
getUnsafeReadBuffer in interface WriteBuffer
Specified by:
getUnsafeReadBuffer in class AbstractWriteBuffer
Returns:
a ReadBuffer that reflects the contents of this WriteBuffer but whose behavior is undefined if the WriteBuffer is modified

toByteArray

public byte[] toByteArray()
Returns a new byte array that holds the complete contents of this WriteBuffer.

This method is functionally equivalent to the following code:


 return getUnsafeReadBuffer().toByteArray();
 
Specified by:
toByteArray in interface WriteBuffer
Overrides:
toByteArray in class AbstractWriteBuffer
Returns:
the contents of this WriteBuffer as a byte[]

toBinary

public Binary toBinary()
Returns a new Binary object that holds the complete contents of this WriteBuffer.

This method is functionally equivalent to the following code:


 return getUnsafeReadBuffer().toBinary();
 
Specified by:
toBinary in interface WriteBuffer
Overrides:
toBinary in class AbstractWriteBuffer
Returns:
the contents of this WriteBuffer as a Binary object

checkBounds

protected void checkBounds(int of,
                           int cb)
Test an offset and length of data to write to see if it can be written to this buffer.
Parameters:
of - offset to write data at
cb - length in bytes of data

updateLength

protected void updateLength(int cb)
Update the length if the passed length is greater than the current buffer length.
Parameters:
cb - the possible new length

copyStream

protected int copyStream(int ofDest,
                         InputStreaming stream,
                         int cbMax)
                  throws java.io.IOException
Store the remaining contents of the specified InputStreaming object at the specified offset within this buffer.
Overrides:
copyStream in class AbstractWriteBuffer
Parameters:
ofDest - the offset within this buffer to store the passed data
stream - the stream of bytes to read and store in this buffer
cbMax - the maximum number of bytes to copy
Returns:
the actual number of bytes read from the InputStreaming object and written to this buffer
Throws:
java.io.IOException - if an IOException occurs reading from the passed stream or if the limit is reached without emptying the source stream

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Oracle® Coherence Java API Reference
Release 3.7.0.0

E18683-01


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