org.apache.hadoop.chukwa.datacollection.agent
Class ChukwaAgent

java.lang.Object
  org.apache.hadoop.chukwa.datacollection.agent.ChukwaAgent

public class ChukwaAgent
extends Object

The local agent daemon that runs on each machine. This class is designed to be embeddable, for use in testing.

Nested Class Summary

static class

ChukwaAgent.AlreadyRunningException

Constructor Summary

ChukwaAgent()

ChukwaAgent(org.apache.hadoop.conf.Configuration conf)

Method Summary

int	adaptorCount()
Map<Long,Adaptor>	getAdaptorList()
static ChukwaAgent	getAgent()
org.apache.hadoop.conf.Configuration	getConfiguration()
Connector	getConnector()
int	getControllerPort()
long	getOffset(Adaptor a) Returns the last offset at which a given adaptor was checkpointed
static void	main(String[] args)
long	processCommand(String cmd)
protected static org.apache.hadoop.conf.Configuration	readConfig()
void	reportCommit(Adaptor src, long uuid)
boolean	restoreFromCheckpoint() Tries to restore from a checkpoint file in checkpointDir.
void	shutdown()
void	shutdown(boolean exit) Triggers agent shutdown.
long	stopAdaptor(long number, boolean gracefully) Stop the adaptor with given ID number.
void	writeCheckpoint() Called periodically to write checkpoints

Methods inherited from class java.lang.Object

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

Constructor Detail

ChukwaAgent

public ChukwaAgent()
            throws ChukwaAgent.AlreadyRunningException

Throws:

ChukwaAgent.AlreadyRunningException

ChukwaAgent

public ChukwaAgent(org.apache.hadoop.conf.Configuration conf)
            throws ChukwaAgent.AlreadyRunningException

Throws:

ChukwaAgent.AlreadyRunningException

Method Detail

getAgent

public static ChukwaAgent getAgent()

getControllerPort

public int getControllerPort()

main

public static void main(String[] args)
                 throws AdaptorException

Parameters:

args -

Throws:

AdaptorException

adaptorCount

public int adaptorCount()

Returns:

the number of running adaptors inside this local agent

processCommand

public long processCommand(String cmd)

restoreFromCheckpoint

public boolean restoreFromCheckpoint()
                              throws IOException

Tries to restore from a checkpoint file in checkpointDir. There should usually only be one checkpoint present -- two checkpoints present implies a crash during writing the higher-numbered one. As a result, this method chooses the lowest-numbered file present. Lines in the checkpoint file are processed one at a time with processCommand();

Returns:

true if the restore succeeded

Throws:

IOException

writeCheckpoint

public void writeCheckpoint()
                     throws IOException

Called periodically to write checkpoints

Throws:

IOException

reportCommit

public void reportCommit(Adaptor src,
                         long uuid)

getAdaptorList

public Map<Long,Adaptor> getAdaptorList()

stopAdaptor

public long stopAdaptor(long number,
                        boolean gracefully)

Stop the adaptor with given ID number. Takes a parameter to indicate whether the adaptor should force out all remaining data, or just exit abruptly. If the adaptor is written correctly, its offset won't change after returning from shutdown.

Parameters:

number - the adaptor to stop

gracefully - if true, shutdown, if false, hardStop

Returns:

the number of bytes synched at stop. -1 on error

getConfiguration

public org.apache.hadoop.conf.Configuration getConfiguration()

getConnector

public Connector getConnector()

readConfig

protected static org.apache.hadoop.conf.Configuration readConfig()

shutdown

public void shutdown()

shutdown

public void shutdown(boolean exit)

Triggers agent shutdown. For now, this method doesn't shut down adaptors explicitly. It probably should.

getOffset

public long getOffset(Adaptor a)

Returns the last offset at which a given adaptor was checkpointed

Parameters:

a - the adaptor in question

Returns:

that adaptor's last-checkpointed offset