com.spotify.helios.agent

Class TaskHistoryWriter

java.lang.Object

com.google.common.util.concurrent.AbstractIdleService

com.spotify.helios.agent.TaskHistoryWriter

All Implemented Interfaces:

com.google.common.util.concurrent.Service, Runnable

public class TaskHistoryWriter
extends com.google.common.util.concurrent.AbstractIdleService
implements Runnable

Writes task history to ZK, and attempts to gracefully handle the case where ZK is down, and tries to lose the right things if it has to lose stuff.

Just some breadcrumbs so next time, the person that follows me can understand why things are the way they are.

Theory of operation: 1. saveHistoryItem should never block for any significant amount of time. Specifically, it should not block on ZK being in any particular state, and ideally not while a file write is occurring, as the file may get large if ZK has been away for a long time. 2. We limit each job to max 30 events in memory (and in ZK for that matter) 3. Maximum of 600 total events, so as not to consume all available memory.

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.common.util.concurrent.Service

com.google.common.util.concurrent.Service.Listener, com.google.common.util.concurrent.Service.State

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_NUMBER_STATUS_EVENTS_TO_RETAIN

Constructor Summary

Constructors

Constructor and Description
TaskHistoryWriter(String hostname, ZooKeeperClient client, Path backingFile)

Method Summary

Modifier and Type	Method and Description
boolean	isEmpty()
void	run()
void	saveHistoryItem(com.spotify.helios.common.descriptors.TaskStatus status)
void	saveHistoryItem(com.spotify.helios.common.descriptors.TaskStatus status, long timestamp)
protected void	shutDown()
protected void	startUp()

Methods inherited from class com.google.common.util.concurrent.AbstractIdleService

addListener, awaitRunning, awaitRunning, awaitTerminated, awaitTerminated, executor, failureCause, isRunning, serviceName, startAsync, state, stopAsync, toString

Methods inherited from class java.lang.Object

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

Field Detail

MAX_NUMBER_STATUS_EVENTS_TO_RETAIN

public static final int MAX_NUMBER_STATUS_EVENTS_TO_RETAIN

See Also:

Constant Field Values

Constructor Detail

TaskHistoryWriter

public TaskHistoryWriter(String hostname,
                         ZooKeeperClient client,
                         Path backingFile)
                  throws IOException,
                         InterruptedException

Throws:

IOException

InterruptedException

Method Detail

startUp

protected void startUp()
                throws Exception

Specified by:

startUp in class com.google.common.util.concurrent.AbstractIdleService

Throws:

Exception

shutDown

protected void shutDown()
                 throws Exception

Specified by:

shutDown in class com.google.common.util.concurrent.AbstractIdleService

Throws:

Exception

saveHistoryItem

public void saveHistoryItem(com.spotify.helios.common.descriptors.TaskStatus status)
                     throws InterruptedException

Throws:

InterruptedException

saveHistoryItem

public void saveHistoryItem(com.spotify.helios.common.descriptors.TaskStatus status,
                            long timestamp)
                     throws InterruptedException

Throws:

InterruptedException

isEmpty

public boolean isEmpty()

run

public void run()

Specified by:

run in interface Runnable