io.pravega.client.byteStream

Class ByteStreamWriter

java.lang.Object

java.io.OutputStream

io.pravega.client.byteStream.ByteStreamWriter

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable

public abstract class ByteStreamWriter
extends java.io.OutputStream

Allows for writing raw bytes directly to a segment. This is intended as low level building block for creating higher level components. As such it can break things. This class does not frame, attach headers, or otherwise modify the bytes written to it in any way. So unlike EventStreamWriter or RevisionedStreamClient the data written cannot be split apart when read. As such, any bytes written by this API can ONLY be read using ByteStreamReader. Similarly, unless some sort of framing is added it is probably an error to have multiple ByteStreamWriters write to the same segment as this will result in interleaved data. The methods on this class are non-blocking unless otherwise specified. As such data passed to a OutputStream.write(byte[]) call cannot be assumed to be persisted until a flush has been called. It is safe to invoke methods on this class from multiple threads but doing so will not result in an increase in performance.

Constructor Summary

Constructors

Constructor and Description
ByteStreamWriter()

Method Summary

Modifier and Type	Method and Description
abstract void	close() Flushes the buffer and closes the writer.
abstract void	closeAndSeal() Closes the writer similar to close() but also seals it so that no future writes can ever be made.
abstract long	fetchTailOffset() This makes a synchronous RPC call to the server to obtain the total number of bytes written to the segment in its history.
abstract void	flush() Blocks until all data written has been durably persisted.
abstract void	write(byte[] b, int off, int len) Writes the provided data to the segment.
abstract void	write(java.nio.ByteBuffer src) Similar to write(byte[], int, int) Writes the provided data to the segment.

Methods inherited from class java.io.OutputStream

write, write

Methods inherited from class java.lang.Object

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

Constructor Detail

ByteStreamWriter

public ByteStreamWriter()

Method Detail

write

public abstract void write(java.nio.ByteBuffer src)
                    throws java.io.IOException

Similar to write(byte[], int, int) Writes the provided data to the segment. The data is buffered internally to avoid blocking. As such it cannot be assumed to be durably stored until a flush completes. It is intended that this method not block, but it may in the event that the server becomes disconnected for sufficiently long or is sufficiently slow that that backlog of data to be written becomes a memory issue.

Parameters:

src - The bytes to write.

Throws:

java.io.IOException - If for any reason an error occurs writing the data, including if the stream is sealed.

write

public abstract void write(byte[] b,
                           int off,
                           int len)
                    throws java.io.IOException

Writes the provided data to the segment. The data is buffered internally to avoid blocking. As such it cannot be assumed to be durably stored until a flush completes. It is intended that this method not block, but it may in the event that the server becomes disconnected for sufficiently long or is sufficiently slow that that backlog of data to be written becomes a memory issue.

Overrides:

write in class java.io.OutputStream

Throws:

java.io.IOException

See Also:

OutputStream.write(byte[], int, int)

close

public abstract void close()
                    throws java.io.IOException

Flushes the buffer and closes the writer. If there is data to flush, this is a blocking method.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class java.io.OutputStream

Throws:

java.io.IOException

See Also:

OutputStream.close()

flush

public abstract void flush()
                    throws java.io.IOException

Blocks until all data written has been durably persisted.

Specified by:

flush in interface java.io.Flushable

Overrides:

flush in class java.io.OutputStream

Throws:

java.io.IOException - If for any reason the flush fails including if the stream is sealed.

See Also:

OutputStream.flush()

closeAndSeal

public abstract void closeAndSeal()
                           throws java.io.IOException

Closes the writer similar to close() but also seals it so that no future writes can ever be made.

Throws:

java.io.IOException - If for any reason the flush fails including if the stream is sealed.

fetchTailOffset

public abstract long fetchTailOffset()

This makes a synchronous RPC call to the server to obtain the total number of bytes written to the segment in its history. This is the sum total of the bytes written in all calls to OutputStream.write(byte[]) that have been flushed. It does not include data that was passed to OutputStream.write(byte[]) but which has not yet been persisted.

Returns:

The tail offset