com.espertech.esper.epl.metric

Class StatementMetricArray

java.lang.Object

com.espertech.esper.epl.metric.StatementMetricArray

public class StatementMetricArray
extends Object

Holder for statement group's statement metrics.

Changes to StatementMetric instances must be done in a read-lock:

 getRwLock.readLock.lock()
 metric = getAddMetric(index)
 metric.accountFor(cpu, wall, etc)
 getRwLock.readLock.unlock()
 

All other changes are done under write lock for this class.

This is a collection backed by an array that grows by 50% each time expanded, maintains a free/busy list of statement names, maintains an element number of last used element.

The flush operaton copies the complete array, thereby keeping array size. Statement names are only removed on the next flush.

Constructor Summary

Constructors

Constructor and Description
StatementMetricArray(String engineURI, String name, int initialSize, boolean isReportInactive) Ctor.

Method Summary

Modifier and Type	Method and Description
int	addStatementGetIndex(String statementName) Adds a statement and returns the index added at.
StatementMetric[]	flushMetrics() Flushes the existing metrics via array copy and swap.
StatementMetric	getAddMetric(int index) Returns an existing or creates a new statement metric for the index.
ManagedReadWriteLock	getRwLock() Returns the read-write lock, for read-lock when modifications are made.
void	removeStatement(String statementName) Remove a statement.
int	sizeLastElement() Returns maximum collection size (last used element), which may not truely reflect the number of actual statements held as some slots may empty up when statements are removed.

Methods inherited from class java.lang.Object

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

Constructor Detail

StatementMetricArray

public StatementMetricArray(String engineURI,
                            String name,
                            int initialSize,
                            boolean isReportInactive)

Ctor.

Parameters:

engineURI - engine URI

name - name of statement group

initialSize - initial size of array

isReportInactive - true to indicate to report on inactive statements

Method Detail

removeStatement

public void removeStatement(String statementName)

Remove a statement.

Next flush actually frees the slot that this statement occupied.

Parameters:

statementName - to remove

addStatementGetIndex

public int addStatementGetIndex(String statementName)

Adds a statement and returns the index added at.

May reuse an empty slot, grow the underlying array, or append to the end.

Parameters:

statementName - to add

Returns:

index added to

flushMetrics

public StatementMetric[] flushMetrics()

Flushes the existing metrics via array copy and swap.

May report all statements (empty and non-empty slots) and thereby null values.

Returns null to indicate no reports to do.

Returns:

metrics

getRwLock

public ManagedReadWriteLock getRwLock()

Returns the read-write lock, for read-lock when modifications are made.

Returns:

lock

getAddMetric

public StatementMetric getAddMetric(int index)

Returns an existing or creates a new statement metric for the index.

Parameters:

index - of statement

Returns:

metric to modify under read lock

sizeLastElement

public int sizeLastElement()

Returns maximum collection size (last used element), which may not truely reflect the number of actual statements held as some slots may empty up when statements are removed.

Returns:

known maximum size