org.sape.carbon.services.instrumentation.statistics
Class DefaultStatisticsInterceptor

java.lang.Object
  |
  +--org.sape.carbon.services.instrumentation.statistics.DefaultStatisticsInterceptor

All Implemented Interfaces:

Decorator, Interceptor, StatisticsInterceptor

public class DefaultStatisticsInterceptor

extends Object

implements StatisticsInterceptor, Interceptor

This Component Interceptor can be utilized to track the execution of Carbon components. It can be configured in a component template as shown here:

  <!-- The statistics Assistant -->
   <DecoratorConfiguration>
      <Factory>org.sape.carbon.services.component.assistants.StatisticsInterceptorFactory</Factory>
   </DecoratorConfiguration>
 

WARNING: This does not guarantee accurate statistics... it simply keeps there from being innacurrate information in each MethodStat object and from threads stepping on eachother while writing. When reading, it is possible to read some of the data inconsistently. This is accepted as this is designed to be "pretty" accurate, with little to no contention on basic method calls, and only.

Copyright 2002 Sapient

Since:

carbon 1.0

Version:

$Revision: 1.11 $($Author: ghinkl $ / $Date: 2003/10/09 19:33:08 $)

Author:

Greg Hinkle, January 2002

Nested Class Summary

static class

DefaultStatisticsInterceptor.MethodStats This inner class is used to track information about an individual method on a specific component.

Field Summary

private Component	componentReference The reference to the component object
private long	componentStartTime The general start time of the component
private FunctionalInterface	functionalImplementation The reference to the implementation object of the component
private ThreadLocal	localMethodStats This threadlocal will hold a local map of methods to MethodStats objects, allowing each thread to accurately accumulate statistics information with no locking or contention.
private org.apache.commons.logging.Log	log The handle to Apache-commons logger
private Map	methodStats The map of component methods to Lists of MethodStat objects.
protected Interceptor	nextInterceptor The reference to the next interceptor in the chain
private long	statisticsStartTime The time at which statistics tracking began.

Constructor Summary

private	DefaultStatisticsInterceptor() This object should not be insantiated manually, but only by the Component construction subsystem.
	DefaultStatisticsInterceptor(FunctionalInterface functionalImplementation) The constructor used by the component interceptor factory to build this interceptor.

Method Summary

private void	appendClassInfo(StringBuffer buf, ClassTree.ClassTreeNode node, int depth) Recursively appends class information to the buffer for the given node and all child nodes.
long	getCallCounts() The count of calls to the component.
Class[]	getExposedInterfaces() This should return the list of interfaces that a decorator wishes to expose through the component proxy.
Collection	getMethodStats() A collection of the MethodStats for each method in the instrumented component.
Date	getStartDate() The start date of the assisted component.
long	getStartTime() Returns the start time of this component
String	getStatsReport() Builds an HTML report of information about the assisted component.
Object	invoke(Invocation invocation) This method must implement the invocation of any necessary actions and the chaining the next interceptor.
void	logStats() Logs the statistics for the tracked component to the default logging component.
void	resetStats() Resets the statistics being tracked on the component to zero.
void	setComponentReference(Component component) Called after creation to pass a reference to the component to each of its decorators.
void	setNextInterceptor(Interceptor interceptor) This method sets the next interceptor as the next in the chain from the current interceptor.

Methods inherited from class java.lang.Object

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

Field Detail

log

private org.apache.commons.logging.Log log

The handle to Apache-commons logger

methodStats

private Map methodStats

The map of component methods to Lists of MethodStat objects. Each method has an associated list of MethodStats objects (one for each thread that has used the component). Each thread also stores a reference to this object in ThreadLocal. Only one thread will ever update a specific MethodStats object, whereas any method may read them here to aggregate the stats information. WARNING: This does not guarantee accurate statistics... it simply keeps there from being innacurrate information in each MethodStat object and from threads stepping on eachother while writing. When reading, it is possible to read some of the data inconsistently. This is accepted as this is designed to be "pretty" accurate, with little to no contention on basic method calls, and only.

localMethodStats

private ThreadLocal localMethodStats

This threadlocal will hold a local map of methods to MethodStats objects, allowing each thread to accurately accumulate statistics information with no locking or contention.

componentStartTime

private long componentStartTime

The general start time of the component

statisticsStartTime

private long statisticsStartTime

The time at which statistics tracking began. This is either when the component was started, or the last time resetStatistics was called.

componentReference

private Component componentReference

The reference to the component object

functionalImplementation

private FunctionalInterface functionalImplementation

The reference to the implementation object of the component

nextInterceptor

protected Interceptor nextInterceptor

The reference to the next interceptor in the chain

Constructor Detail

DefaultStatisticsInterceptor

private DefaultStatisticsInterceptor()

This object should not be insantiated manually, but only by the Component construction subsystem.

DefaultStatisticsInterceptor

public DefaultStatisticsInterceptor(FunctionalInterface functionalImplementation)

The constructor used by the component interceptor factory to build this interceptor.

Parameters:

functionalImplementation - a reference to the implementation object behind the component.

Method Detail

getStartTime

public long getStartTime()

Returns the start time of this component

Specified by:

getStartTime in interface StatisticsInterceptor

Returns:

the start time, in milleseconds, of the component

getStartDate

public Date getStartDate()

The start date of the assisted component.

Specified by:

getStartDate in interface StatisticsInterceptor

Returns:

the date object of when the assisted component was started

getCallCounts

public long getCallCounts()

The count of calls to the component.

Specified by:

getCallCounts in interface StatisticsInterceptor

Returns:

the number of times any method on the assisted component were called.

getMethodStats

public Collection getMethodStats()

A collection of the MethodStats for each method in the instrumented component. This method works by aggregating the statistics information for each thread. See the warning above about its accuracy.

Specified by:

getMethodStats in interface StatisticsInterceptor

Returns:

an unmodifiable collection of method MethodStats objects.

See Also:

DefaultStatisticsInterceptor

logStats

public void logStats()

Logs the statistics for the tracked component to the default logging component.

Specified by:

logStats in interface StatisticsInterceptor

setNextInterceptor

public void setNextInterceptor(Interceptor interceptor)

This method sets the next interceptor as the next in the chain from the current interceptor.

Specified by:

setNextInterceptor in interface Interceptor

Parameters:

interceptor - the next interceptor in the chain

getExposedInterfaces

public Class[] getExposedInterfaces()

This should return the list of interfaces that a decorator wishes to expose through the component proxy. This is used by the component factory to determine what interfaces the component proxy will implement.

Specified by:

getExposedInterfaces in interface Decorator

Returns:

Class[] an array of interfaces

invoke

public Object invoke(Invocation invocation)
              throws Throwable

This method must implement the invocation of any necessary actions and the chaining the next interceptor.

Specified by:

invoke in interface Interceptor

Parameters:

invocation - the invocation to execute

Returns:

the results of the invocation's execution

Throws:

Throwable - indicates an error in the interceptor chain

setComponentReference

public void setComponentReference(Component component)

Description copied from interface: Decorator

Called after creation to pass a reference to the component to each of its decorators. The component reference should not be used within this method because not all other interceptors have this reference yet and they may rely on this reference thus leading to null pointer exceptions.

Specified by:

setComponentReference in interface Decorator

Parameters:

component - a reference to the component that this interceptor is assisting

See Also:

Decorator.setComponentReference(org.sape.carbon.core.component.Component)

getStatsReport

public String getStatsReport()

Builds an HTML report of information about the assisted component. This report contains general information about the component as well as statistics on the total method calls and information about each method of the component.

Note: It should be noted that the failure counts are only updated apon the next call to a method that has failed. If a component is failing, there well may be uncounted failures, up to a count of the total threads that have had failures on the component.

Specified by:

getStatsReport in interface StatisticsInterceptor

Returns:

an html report of information about the tracked component

appendClassInfo

private void appendClassInfo(StringBuffer buf,
                             ClassTree.ClassTreeNode node,
                             int depth)

Recursively appends class information to the buffer for the given node and all child nodes.

Parameters:

buf - the buffer to append to

node - the node to append

depth - the depth of recursion of the child nodes.

resetStats

public void resetStats()

Resets the statistics being tracked on the component to zero.

Specified by:

resetStats in interface StatisticsInterceptor