Package org.apache.hadoop.hdfs.server.namenode

Class EditLogFileInputStream

java.lang.Object

org.apache.hadoop.hdfs.server.namenode.EditLogInputStream

org.apache.hadoop.hdfs.server.namenode.EditLogFileInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

@Private
public class EditLogFileInputStream
extends EditLogInputStream

An implementation of the abstract class EditLogInputStream, which reads edits from a file. That file may be either on the local disk or accessible via a URL.

Constructor Summary

Constructors

Constructor	Description
EditLogFileInputStream(java.io.File name, long firstTxId, long lastTxId, boolean isInProgress)	Open an EditLogInputStream for the given file.

Method Summary

Modifier and Type	Method	Description
void	close()	Close the stream.
static EditLogInputStream	fromByteString(org.apache.hadoop.thirdparty.protobuf.ByteString bytes, long startTxId, long endTxId, boolean inProgress)	Create an EditLogInputStream from a ByteString, i.e.
static EditLogInputStream	fromUrl(org.apache.hadoop.hdfs.web.URLConnectionFactory connectionFactory, java.net.URL url, long startTxId, long endTxId, boolean inProgress)	Open an EditLogInputStream for the given URL.
long	getFirstTxId()
long	getLastTxId()
java.lang.String	getName()
long	getPosition()	Get the "position" of in the stream.
int	getVersion(boolean verifyVersion)	Get the layout version of the data in the stream.
boolean	isInProgress()	Return true if this stream is in progress, false if it is finalized.
boolean	isLocalLog()	Returns true if we are currently reading the log from a local disk or an even faster data source (e.g.
long	length()	Return the size of the current edits log or -1 if unknown.
protected FSEditLogOp	nextOp()	Get the next operation from the stream storage.
protected FSEditLogOp	nextValidOp()	Get the next valid operation from the stream storage.
protected long	scanNextOp()	Go through the next operation from the stream storage.
void	setMaxOpSize(int maxOpSize)	Set the maximum opcode size in bytes.
java.lang.String	toString()

Methods inherited from class org.apache.hadoop.hdfs.server.namenode.EditLogInputStream

getCurrentStreamName, readOp, resync, skipUntil

Methods inherited from class java.lang.Object

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

Constructor Detail

EditLogFileInputStream

public EditLogFileInputStream(java.io.File name,
                              long firstTxId,
                              long lastTxId,
                              boolean isInProgress)

Open an EditLogInputStream for the given file.

Parameters:

name - filename to open

firstTxId - first transaction found in file

lastTxId - last transaction id found in file

Method Detail

fromUrl

public static EditLogInputStream fromUrl(org.apache.hadoop.hdfs.web.URLConnectionFactory connectionFactory,
                                         java.net.URL url,
                                         long startTxId,
                                         long endTxId,
                                         boolean inProgress)

Open an EditLogInputStream for the given URL.

Parameters:

connectionFactory - the URLConnectionFactory used to create the connection.

url - the url hosting the log

startTxId - the expected starting txid

endTxId - the expected ending txid

inProgress - whether the log is in-progress

Returns:

a stream from which edits may be read

fromByteString

public static EditLogInputStream fromByteString(org.apache.hadoop.thirdparty.protobuf.ByteString bytes,
                                                long startTxId,
                                                long endTxId,
                                                boolean inProgress)

Create an EditLogInputStream from a ByteString, i.e. an in-memory collection of bytes.

Parameters:

bytes - The byte string to read from

startTxId - the expected starting transaction ID

endTxId - the expected ending transaction ID

inProgress - whether the log is in-progress

Returns:

An edit stream to read from

getFirstTxId

public long getFirstTxId()

Specified by:

getFirstTxId in class EditLogInputStream

Returns:

the first transaction which will be found in this stream

getLastTxId

public long getLastTxId()

Specified by:

getLastTxId in class EditLogInputStream

Returns:

the last transaction which will be found in this stream

getName

public java.lang.String getName()

Specified by:

getName in class EditLogInputStream

Returns:

the name of the EditLogInputStream

scanNextOp

protected long scanNextOp()
                   throws java.io.IOException

Description copied from class: EditLogInputStream

Go through the next operation from the stream storage.

Overrides:

scanNextOp in class EditLogInputStream

Returns:

the txid of the next operation.

Throws:

java.io.IOException

nextOp

protected FSEditLogOp nextOp()
                      throws java.io.IOException

Description copied from class: EditLogInputStream

Get the next operation from the stream storage.

Specified by:

nextOp in class EditLogInputStream

Returns:

an operation from the stream or null if at end of stream

Throws:

java.io.IOException - if there is an error reading from the stream

nextValidOp

protected FSEditLogOp nextValidOp()

Description copied from class: EditLogInputStream

Get the next valid operation from the stream storage. This is exactly like nextOp, except that we attempt to skip over damaged parts of the edit log

Overrides:

nextValidOp in class EditLogInputStream

Returns:

an operation from the stream or null if at end of stream

getVersion

public int getVersion(boolean verifyVersion)
               throws java.io.IOException

Description copied from class: EditLogInputStream

Get the layout version of the data in the stream.

Specified by:

getVersion in class EditLogInputStream

Returns:

the layout version of the ops in the stream.

Throws:

java.io.IOException - if there is an error reading the version

getPosition

public long getPosition()

Description copied from class: EditLogInputStream

Get the "position" of in the stream. This is useful for debugging and operational purposes. Different stream types can have a different meaning for what the position is. For file streams it means the byte offset from the start of the file.

Specified by:

getPosition in class EditLogInputStream

Returns:

the position in the stream

close

public void close()
           throws java.io.IOException

Description copied from class: EditLogInputStream

Close the stream.

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Specified by:

close in class EditLogInputStream

Throws:

java.io.IOException - if an error occurred while closing

length

public long length()
            throws java.io.IOException

Description copied from class: EditLogInputStream

Return the size of the current edits log or -1 if unknown.

Specified by:

length in class EditLogInputStream

Returns:

long size of the current edits log or -1 if unknown

Throws:

java.io.IOException

isInProgress

public boolean isInProgress()

Description copied from class: EditLogInputStream

Return true if this stream is in progress, false if it is finalized.

Specified by:

isInProgress in class EditLogInputStream

toString

public java.lang.String toString()

Overrides:

toString in class EditLogInputStream

setMaxOpSize

public void setMaxOpSize(int maxOpSize)

Description copied from class: EditLogInputStream

Set the maximum opcode size in bytes.

Specified by:

setMaxOpSize in class EditLogInputStream

isLocalLog

public boolean isLocalLog()

Description copied from class: EditLogInputStream

Returns true if we are currently reading the log from a local disk or an even faster data source (e.g. a byte buffer).

Specified by:

isLocalLog in class EditLogInputStream