voldemort.cluster.failuredetector
Class AbstractFailureDetector

java.lang.Object
  voldemort.cluster.failuredetector.AbstractFailureDetector

All Implemented Interfaces:

FailureDetector

Direct Known Subclasses:

AsyncRecoveryFailureDetector, BannagePeriodFailureDetector

public abstract class AbstractFailureDetector
extends java.lang.Object
implements FailureDetector

AbstractFailureDetector serves as a building block for FailureDetector implementations.

Field Summary

protected FailureDetectorConfig	failureDetectorConfig
protected java.util.Map<java.lang.Integer,voldemort.cluster.failuredetector.NodeStatus>	idNodeStatusMap
protected java.util.concurrent.ConcurrentHashMap<FailureDetectorListener,java.lang.Object>	listeners
protected org.apache.log4j.Logger	logger

Constructor Summary

protected

AbstractFailureDetector(FailureDetectorConfig failureDetectorConfig)

Method Summary

void	addFailureDetectorListener(FailureDetectorListener failureDetectorListener) Adds a FailureDetectorListener instance that can receive event callbacks about node availability state changes.
protected void	checkArgs(Node node, long requestTime)
protected void	checkNodeArg(Node node)
void	destroy() Cleans up any open resources in preparation for shutdown.
int	getAvailableNodeCount() Returns the number of nodes that are considered to be available at the time of calling.
java.lang.String	getAvailableNodes()
FailureDetectorConfig	getConfig() Retrieves the FailureDetectorConfig instance with which this FailureDetector was constructed.
long	getLastChecked(Node node) Returns the number of milliseconds since the node was last checked for availability.
int	getNodeCount() Returns the number of nodes that are in the set of all nodes at the time of calling.
protected voldemort.cluster.failuredetector.NodeStatus	getNodeStatus(Node node)
java.lang.String	getUnavailableNodes()
void	removeFailureDetectorListener(FailureDetectorListener failureDetectorListener) Removes a FailureDetectorListener instance from the event listener list.
protected void	setAvailable(Node node)
protected void	setUnavailable(Node node, UnreachableStoreException e)
void	waitForAvailability(Node node) waitForAvailability causes the calling thread to block until the given Node is available.

Methods inherited from class java.lang.Object

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

Methods inherited from interface voldemort.cluster.failuredetector.FailureDetector

isAvailable, recordException, recordSuccess

Field Detail

failureDetectorConfig

protected final FailureDetectorConfig failureDetectorConfig

listeners

protected final java.util.concurrent.ConcurrentHashMap<FailureDetectorListener,java.lang.Object> listeners

idNodeStatusMap

protected final java.util.Map<java.lang.Integer,voldemort.cluster.failuredetector.NodeStatus> idNodeStatusMap

logger

protected final org.apache.log4j.Logger logger

Constructor Detail

AbstractFailureDetector

protected AbstractFailureDetector(FailureDetectorConfig failureDetectorConfig)

Method Detail

addFailureDetectorListener

public void addFailureDetectorListener(FailureDetectorListener failureDetectorListener)

Description copied from interface: FailureDetector

Adds a FailureDetectorListener instance that can receive event callbacks about node availability state changes.

Notes:

1. Make sure to clean up the listener by invoking removeFailureDetectorListener
2. Make sure that the FailureDetectorListener implementation properly implements the hashCode/equals methods

   Note for implementors: When adding a FailureDetectorListener that has already been added, this should not add a second instance but should effectively be a no-op.

   Specified by:

   addFailureDetectorListener in interface FailureDetector

   Parameters:

   failureDetectorListener - FailureDetectorListener that receives events

   See Also:

   FailureDetector.removeFailureDetectorListener(voldemort.cluster.failuredetector.FailureDetectorListener)

removeFailureDetectorListener

public void removeFailureDetectorListener(FailureDetectorListener failureDetectorListener)

Description copied from interface: FailureDetector

Removes a FailureDetectorListener instance from the event listener list.

Note for implementors: When removing a FailureDetectorListener that has already been removed or was never in the list, this should not raise any errors but should effectively be a no-op.

Specified by:

removeFailureDetectorListener in interface FailureDetector

Parameters:

failureDetectorListener - FailureDetectorListener that was receiving events

See Also:

FailureDetector.addFailureDetectorListener(voldemort.cluster.failuredetector.FailureDetectorListener)

getConfig

public FailureDetectorConfig getConfig()

Description copied from interface: FailureDetector

Retrieves the FailureDetectorConfig instance with which this FailureDetector was constructed.

Specified by:

getConfig in interface FailureDetector

Returns:

FailureDetectorConfig

getAvailableNodes

public java.lang.String getAvailableNodes()

getUnavailableNodes

public java.lang.String getUnavailableNodes()

getAvailableNodeCount

public int getAvailableNodeCount()

Description copied from interface: FailureDetector

Returns the number of nodes that are considered to be available at the time of calling. Letting n = the results of getNodeCount(), the return value is bounded in the range [0..n].

Specified by:

getAvailableNodeCount in interface FailureDetector

Returns:

Number of available nodes

See Also:

FailureDetector.getNodeCount()

getNodeCount

public int getNodeCount()

Description copied from interface: FailureDetector

Returns the number of nodes that are in the set of all nodes at the time of calling.

Specified by:

getNodeCount in interface FailureDetector

Returns:

Number of nodes

See Also:

FailureDetector.getAvailableNodeCount()

waitForAvailability

public void waitForAvailability(Node node)
                         throws java.lang.InterruptedException

Description copied from interface: FailureDetector

waitForAvailability causes the calling thread to block until the given Node is available. If the node is already available, this will simply return.

Specified by:

waitForAvailability in interface FailureDetector

Parameters:

node - Node on which to wait

Throws:

java.lang.InterruptedException - Thrown if the thread is interrupted

getLastChecked

public long getLastChecked(Node node)

Description copied from interface: FailureDetector

Returns the number of milliseconds since the node was last checked for availability. Because of its lack of precision, this should really only be used for status/reporting.

Specified by:

getLastChecked in interface FailureDetector

Parameters:

node - Node to check

Returns:

Number of milliseconds since the node was last checked for availability

destroy

public void destroy()

Description copied from interface: FailureDetector

Cleans up any open resources in preparation for shutdown.

Note for implementors: After this method is called it is assumed that attempts to call the other methods will either silently fail, throw errors, or return stale information.

Specified by:

destroy in interface FailureDetector

setAvailable

protected void setAvailable(Node node)

setUnavailable

protected void setUnavailable(Node node,
                              UnreachableStoreException e)

getNodeStatus

protected voldemort.cluster.failuredetector.NodeStatus getNodeStatus(Node node)

checkNodeArg

protected void checkNodeArg(Node node)

checkArgs

protected void checkArgs(Node node,
                         long requestTime)