org.apache.hadoop.hbase.regionserver

Class SplitLogWorker

java.lang.Object

org.apache.hadoop.hbase.regionserver.SplitLogWorker

All Implemented Interfaces:

Runnable

@InterfaceAudience.Private
public class SplitLogWorker
extends Object
implements Runnable

This worker is spawned in every regionserver, including master. The Worker waits for log splitting tasks to be put up by the SplitLogManager running in the master and races with other workers in other serves to acquire those tasks. The coordination is done via coordination engine.

If a worker has successfully moved the task from state UNASSIGNED to OWNED then it owns the task. It keeps heart beating the manager by periodically moving the task from UNASSIGNED to OWNED state. On success it moves the task to TASK_DONE. On unrecoverable error it moves task state to ERR. If it cannot continue but wants the master to retry the task then it moves the task state to RESIGNED.

The manager can take a task away from a worker by moving the task from OWNED to UNASSIGNED. In the absence of a global lock there is a unavoidable race here - a worker might have just finished its task when it is stripped of its ownership. Here we rely on the idempotency of the log splitting task for correctness

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SplitLogWorker.TaskExecutor Objects implementing this interface actually do the task that has been acquired by a SplitLogWorker.

Field Summary

Fields

Modifier and Type	Field and Description
private org.apache.hadoop.conf.Configuration	conf
private SplitLogWorkerCoordination	coordination
private static org.slf4j.Logger	LOG
private RegionServerServices	server
(package private) Thread	worker

Constructor Summary

Constructors

Constructor and Description
SplitLogWorker(org.apache.hadoop.conf.Configuration conf, RegionServerServices server, LastSequenceId sequenceIdChecker, WALFactory factory)
SplitLogWorker(Server hserver, org.apache.hadoop.conf.Configuration conf, RegionServerServices server, SplitLogWorker.TaskExecutor splitTaskExecutor)

Method Summary

Modifier and Type	Method and Description
int	getTaskReadySeq() Returns the number of tasks processed by coordination.
void	run()
(package private) static SplitLogWorker.TaskExecutor.Status	splitLog(String filename, CancelableProgressable p, org.apache.hadoop.conf.Configuration conf, RegionServerServices server, LastSequenceId sequenceIdChecker, WALFactory factory)
void	start() start the SplitLogWorker thread
void	stop() stop the SplitLogWorker thread
void	stopTask() If the worker is doing a task i.e.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

private static final org.slf4j.Logger LOG

worker

Thread worker

coordination

private final SplitLogWorkerCoordination coordination

conf

private final org.apache.hadoop.conf.Configuration conf

server

private final RegionServerServices server

Constructor Detail

SplitLogWorker

public SplitLogWorker(Server hserver,
                      org.apache.hadoop.conf.Configuration conf,
                      RegionServerServices server,
                      SplitLogWorker.TaskExecutor splitTaskExecutor)

SplitLogWorker

public SplitLogWorker(org.apache.hadoop.conf.Configuration conf,
                      RegionServerServices server,
                      LastSequenceId sequenceIdChecker,
                      WALFactory factory)

Method Detail

splitLog

static SplitLogWorker.TaskExecutor.Status splitLog(String filename,
                                                   CancelableProgressable p,
                                                   org.apache.hadoop.conf.Configuration conf,
                                                   RegionServerServices server,
                                                   LastSequenceId sequenceIdChecker,
                                                   WALFactory factory)

Returns:

Result either DONE, RESIGNED, or ERR.

run

public void run()

Specified by:

run in interface Runnable

stopTask

public void stopTask()

If the worker is doing a task i.e. splitting a log file then stop the task. It doesn't exit the worker thread.

start

public void start()

start the SplitLogWorker thread

stop

public void stop()

stop the SplitLogWorker thread

getTaskReadySeq

public int getTaskReadySeq()

Returns the number of tasks processed by coordination. This method is used by tests only