com.google.cloud.hadoop.gcsio

Class GoogleCloudStorageReadChannel

java.lang.Object

com.google.cloud.hadoop.gcsio.GoogleCloudStorageReadChannel

All Implemented Interfaces:

SeekableReadableByteChannel, Closeable, AutoCloseable, Channel, ReadableByteChannel

public class GoogleCloudStorageReadChannel
extends Object
implements SeekableReadableByteChannel

Provides seekable read access to GCS.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_BACKOFF_INITIAL_INTERVAL_MILLIS
static int	DEFAULT_BACKOFF_MAX_ELAPSED_TIME_MILLIS
static int	DEFAULT_BACKOFF_MAX_INTERVAL_MILLIS
static double	DEFAULT_BACKOFF_MULTIPLIER
static double	DEFAULT_BACKOFF_RANDOMIZATION_FACTOR

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes this channel.
boolean	isOpen() Tells whether this channel is open.
protected InputStream	openStreamAndSetSize(long newPosition) Opens the underlying stream, sets its position to the given value and sets size based on stream content size.
long	position() Returns this channel's current position.
SeekableReadableByteChannel	position(long newPosition) Sets this channel's position.
int	read(ByteBuffer buffer) Reads from this channel and stores read data in the given buffer.
void	setMaxRetries(int maxRetries) Sets the number of times to automatically retry by re-opening the underlying readChannel whenever an exception occurs while reading from it.
protected void	setSize(long size) Sets size of this channel to the given value.
long	size() Returns size of the object to which this channel is connected.
protected void	validatePosition(long newPosition) Validates that the given position is valid for this channel.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_BACKOFF_INITIAL_INTERVAL_MILLIS

public static final int DEFAULT_BACKOFF_INITIAL_INTERVAL_MILLIS

See Also:

Constant Field Values

DEFAULT_BACKOFF_RANDOMIZATION_FACTOR

public static final double DEFAULT_BACKOFF_RANDOMIZATION_FACTOR

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Constant Field Values

DEFAULT_BACKOFF_MULTIPLIER

public static final double DEFAULT_BACKOFF_MULTIPLIER

See Also:

Constant Field Values

DEFAULT_BACKOFF_MAX_INTERVAL_MILLIS

public static final int DEFAULT_BACKOFF_MAX_INTERVAL_MILLIS

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Constant Field Values

DEFAULT_BACKOFF_MAX_ELAPSED_TIME_MILLIS

public static final int DEFAULT_BACKOFF_MAX_ELAPSED_TIME_MILLIS

See Also:

Constant Field Values

Method Detail

setMaxRetries

public void setMaxRetries(int maxRetries)

Sets the number of times to automatically retry by re-opening the underlying readChannel whenever an exception occurs while reading from it. The count of attempted retries is reset whenever at least one byte is successfully read, so this number of retries refers to retries made without achieving any forward progress.

read

public int read(ByteBuffer buffer)
         throws IOException

Reads from this channel and stores read data in the given buffer.

Specified by:

read in interface ReadableByteChannel

Parameters:

buffer - buffer to read data into

Returns:

number of bytes read or -1 on end-of-stream

Throws:

IOException - on IO error

isOpen

public boolean isOpen()

Tells whether this channel is open.

Specified by:

isOpen in interface Channel

Returns:

a value indicating whether this channel is open

close

public void close()
           throws IOException

Closes this channel.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Channel

Throws:

IOException - on IO error

position

public long position()
              throws IOException

Returns this channel's current position.

Specified by:

position in interface SeekableReadableByteChannel

Returns:

this channel's current position

Throws:

IOException

position

public SeekableReadableByteChannel position(long newPosition)
                                     throws IOException

Sets this channel's position.

Specified by:

position in interface SeekableReadableByteChannel

Parameters:

newPosition - the new position, counting the number of bytes from the beginning.

Returns:

this channel instance

Throws:

FileNotFoundException - if the underlying object does not exist.

IOException - on IO error

size

public long size()
          throws IOException

Returns size of the object to which this channel is connected.

Specified by:

size in interface SeekableReadableByteChannel

Returns:

size of the object to which this channel is connected

Throws:

IOException - on IO error

setSize

protected void setSize(long size)

Sets size of this channel to the given value.

validatePosition

protected void validatePosition(long newPosition)

Validates that the given position is valid for this channel.

openStreamAndSetSize

protected InputStream openStreamAndSetSize(long newPosition)
                                    throws IOException

Opens the underlying stream, sets its position to the given value and sets size based on stream content size.

Parameters:

newPosition - position to seek into the new stream.

Throws:

IOException - on IO error