- Type Parameters:
T- the resource type.
Resource pools usually have a method to acquire a pooled resource and a method to released it back to the pool.
To detect if client code acquires a resource but never releases it, the resource pool can be modified to use a
LeakDetector. The modified resource pool should call
acquired(Object) every time the method to
acquire a resource is called, and
released(Object) every time the method to release the resource is called.
LeakDetector keeps track of these resources and invokes method
leaked(org.eclipse.jetty.util.LeakDetector.LeakInfo) when it detects that a resource has been leaked (that
is, acquired but never released).
To detect whether client code releases a resource without having acquired it, the resource pool can be modified to
check the return value of
released(Object): if false, it means that the resource was not acquired.
This class relies on
System.identityHashCode(Object) to create a unique id for each resource passed to
System.identityHashCode(Object) does not guarantee
that it will not generate the same number for different objects, but in practice the chance of collision is rare.
PhantomReferences to detect leaks.
PhantomReferences are enqueued in their
ReferenceQueue after they have been garbage collected (differently from
are enqueued before). Since the resource is now garbage collected,
LeakDetector checks whether it
has been released and if not, it reports a leak. Using
PhantomReferences is better than overriding
Object.finalize() and works also in those cases where
Object.finalize() is not overridable.
Nested Class SummaryModifier and TypeClassDescription
classInformation about the leak of a resource.
Nested classes/interfaces inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle
Nested classes/interfaces inherited from interface org.eclipse.jetty.util.component.LifeCycle
Method SummaryModifier and TypeMethodDescription
booleanTracks the resource as been acquired.
doStart()Method to override to start the lifecycle
doStop()Method to override to stop the lifecycleGenerates a unique ID for the given resource.
booleanTracks the resource as been released.
Methods inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle
addEventListener, getEventListeners, getState, getState, isFailed, isRunning, isStarted, isStarting, isStopped, isStopping, removeEventListener, setEventListeners, start, stop, toString
acquiredpublic boolean acquired
(T resource)Tracks the resource as been acquired.
resource- the resource that has been acquired
- true whether the resource has been acquired normally, false if the resource has detected a leak (meaning that another acquire occurred before a release of the same resource)
- See Also:
releasedpublic boolean released
(T resource)Tracks the resource as been released.
resource- the resource that has been released
- true whether the resource has been released normally (based on a previous acquire). false if the resource has been released without a prior acquire (such as a double release scenario)
- See Also:
idGenerates a unique ID for the given resource.
resource- the resource to generate the unique ID for
- the unique ID of the given resource
doStartprotected void doStart() throws ExceptionDescription copied from class:
AbstractLifeCycleMethod to override to start the lifecycle
AbstractLifeCycle.StopException- If thrown, the lifecycle will immediately be stopped.
Exception- If there was a problem starting. Will cause a transition to FAILED state
doStopprotected void doStop() throws ExceptionDescription copied from class:
AbstractLifeCycleMethod to override to stop the lifecycle
Exception- If there was a problem stopping. Will cause a transition to FAILED state
runpublic void run()
leakedprotected void leaked
leakInfo- the information about the leak