Class ReferenceManager<G>

Utility class to safely share instances of a certain type across multiple threads, while periodically refreshing them. This class ensures each reference is closed only once all threads have finished using it. It is recommended to consult the documentation of ReferenceManager<G> implementations for their MaybeRefresh() semantics.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk
Inheritance
System.Object
ReferenceManager<G>
ReaderManager
SearcherManager
Namespace: Lucene.Net.Search
Assembly: Lucene.Net.dll
Syntax
public abstract class ReferenceManager<G> : IDisposable where G : class
Type Parameters
Name Description
G

The concrete type that will be Acquire()d and Release(G)d.

Properties

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Current

The current reference

Declaration
protected G Current { get; set; }
Property Value
Type Description
G

Methods

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Acquire()

Obtain the current reference. You must match every call to acquire with one call to Release(G); it's best to do so in a finally clause, and set the reference to null to prevent accidental usage after it has been released.

Declaration
public G Acquire()
Returns
Type Description
G
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AddListener(ReferenceManager.IRefreshListener)

Adds a listener, to be notified when a reference is refreshed/swapped.

Declaration
public virtual void AddListener(ReferenceManager.IRefreshListener listener)
Parameters
Type Name Description
ReferenceManager.IRefreshListener listener
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AfterMaybeRefresh()

Called after a refresh was attempted, regardless of whether a new reference was in fact created.

Declaration
protected virtual void AfterMaybeRefresh()
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DecRef(G)

Decrement reference counting on the given reference.

Declaration
protected abstract void DecRef(G reference)
Parameters
Type Name Description
G reference
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Dispose()

Closes this ReferenceManager to prevent future Acquire()ing. A reference manager should be disposed if the reference to the managed resource should be disposed or the application using the ReferenceManager<G> is shutting down. The managed resource might not be released immediately, if the ReferenceManager<G> user is holding on to a previously Acquire()d reference. The resource will be released once when the last reference is Release(G)d. Those references can still be used as if the manager was still active.

Applications should not Acquire() new references from this manager once this method has been called. Acquire()ing a resource on a disposed ReferenceManager<G> will throw an .

Declaration
public void Dispose()
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Dispose(Boolean)

Called after Dispose(), so subclass can free any resources.

Declaration
protected virtual void Dispose(bool disposing)
Parameters
Type Name Description
System.Boolean disposing
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GetRefCount(G)

Returns the current reference count of the given reference.

Declaration
protected abstract int GetRefCount(G reference)
Parameters
Type Name Description
G reference
Returns
Type Description
System.Int32
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MaybeRefresh()

You must call this (or MaybeRefreshBlocking()), periodically, if you want that Acquire() will return refreshed instances.

Threads: it's fine for more than one thread to call this at once. Only the first thread will attempt the refresh; subsequent threads will see that another thread is already handling refresh and will return immediately. Note that this means if another thread is already refreshing then subsequent threads will return right away without waiting for the refresh to complete.

If this method returns true it means the calling thread either refreshed or that there were no changes to refresh. If it returns false it means another thread is currently refreshing.

Declaration
public bool MaybeRefresh()
Returns
Type Description
System.Boolean
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MaybeRefreshBlocking()

You must call this (or MaybeRefresh()), periodically, if you want that Acquire() will return refreshed instances.

Threads: unlike MaybeRefresh(), if another thread is currently refreshing, this method blocks until that thread completes. It is useful if you want to guarantee that the next call to Acquire() will return a refreshed instance. Otherwise, consider using the non-blocking MaybeRefresh().

Declaration
public void MaybeRefreshBlocking()
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RefreshIfNeeded(G)

Refresh the given reference if needed. Returns null if no refresh was needed, otherwise a new refreshed reference.

Declaration
protected abstract G RefreshIfNeeded(G referenceToRefresh)
Parameters
Type Name Description
G referenceToRefresh
Returns
Type Description
G
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Release(G)

Release the reference previously obtained via Acquire().

NOTE: it's safe to call this after Dispose().

Declaration
public void Release(G reference)
Parameters
Type Name Description
G reference
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RemoveListener(ReferenceManager.IRefreshListener)

Remove a listener added with AddListener(ReferenceManager.IRefreshListener).

Declaration
public virtual void RemoveListener(ReferenceManager.IRefreshListener listener)
Parameters
Type Name Description
ReferenceManager.IRefreshListener listener
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TryIncRef(G)

Try to increment reference counting on the given reference. Returns true if the operation was successful.

Declaration
protected abstract bool TryIncRef(G reference)
Parameters
Type Name Description
G reference
Returns
Type Description
System.Boolean

Extension Methods