Class PresentFilter

IFilter which returns true for IInvocableCacheEntry objects that currently exist in an ICache.

Inheritance

object

PresentFilter

Implements

IEntryFilter

IFilter

IPortableObject

Inherited Members

object.Equals(object, object)

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: Tangosol.Util.Filter

Assembly: Coherence.dll

Syntax

public class PresentFilter : IEntryFilter, IFilter, IPortableObject

Remarks

This filter is intended to be used solely in combination with a ConditionalProcessor and is unnecessary for standard IQueryCache operations.

Constructors

PresentFilter()

Default constructor.

Declaration

public PresentFilter()

Fields

Instance

An instance of the PresentFilter.

Declaration

public static readonly PresentFilter Instance

Field Value

Type	Description
PresentFilter

Methods

ApplyIndex(IDictionary, ICollection)

Filter remaining keys using an IDictionary of available indexes.

Declaration

public IFilter ApplyIndex(IDictionary indexes, ICollection keys)

Parameters

Type	Name	Description
IDictionary	indexes	The available ICacheIndex objects keyed by the related IValueExtractor; read-only.
ICollection	keys	The mutable set of keys that remain to be filtered.

Returns

Type	Description
IFilter	An IFilter object that can be used to process the remaining keys, or null if no additional filter processing is necessary.

Remarks

The filter is responsible for removing all keys from the passed set of keys that the applicable indexes can prove should be filtered. If the filter does not fully evaluate the remaining keys using just the index information, it must return a filter (which may be an IEntryFilter) that can complete the task using an iterating implementation. If, on the other hand, the filter does fully evaluate the remaining keys using just the index information, then it should return null to indicate that no further filtering is necessary.

CalculateEffectiveness(IDictionary, ICollection)

Given an IDictionary of available indexes, determine if this IIndexAwareFilter can use any of the indexes to assist in its processing, and if so, determine how effective the use of that index would be.

Declaration

public int CalculateEffectiveness(IDictionary indexes, ICollection keys)

Parameters

Type	Name	Description
IDictionary	indexes	The available ICacheIndex objects keyed by the related IValueExtractor; read-only.
ICollection	keys	The set of keys that will be filtered; read-only.

Returns

Type	Description
int	An effectiveness estimate of how well this filter can use the specified indexes to filter the specified keys.

Remarks

The returned value is an effectiveness estimate of how well this filter can use the specified indexes to filter the specified keys. An operation that requires no more than a single access to the index content (i.e. Equals, NotEquals) has an effectiveness of one. Evaluation of a single entry is assumed to have an effectiveness that depends on the index implementation and is usually measured as a constant number of the single operations. This number is referred to as evaluation cost.

If the effectiveness of a filter evaluates to a number larger than the keys.size() then a user could avoid using the index and iterate through the keys calling Evaluate rather than ApplyIndex.

Equals(object)

Compare the PresentFilter with another object to determine equality.

Declaration

public override bool Equals(object o)

Parameters

Type	Name	Description
object	o	The PresentFilter to compare to.

Returns

Type	Description
bool	true if this PresentFilter and the passed object are equivalent PresentFilter objects.

Overrides

object.Equals(object)

Evaluate(object)

Apply the test to the object.

Declaration

public virtual bool Evaluate(object o)

Parameters

Type	Name	Description
object	o	An object to which the test is applied.

Returns

Type	Description
bool	true if the test passes, false otherwise.

EvaluateEntry(ICacheEntry)

Apply the test to an ICacheEntry.

Declaration

public virtual bool EvaluateEntry(ICacheEntry entry)

Parameters

Type	Name	Description
ICacheEntry	entry	The ICacheEntry to evaluate; never null.

Returns

Type	Description
bool	true if the test passes, false otherwise.

GetHashCode()

Determine a hash value for the PresentFilter object according to the general object.GetHashCode() contract.

Declaration

public override int GetHashCode()

Returns

Type	Description
int	An integer hash value for this PresentFilter object.

Overrides

object.GetHashCode()

ReadExternal(IPofReader)

Restore the contents of a user type instance by reading its state using the specified IPofReader object.

Declaration

public virtual void ReadExternal(IPofReader reader)

Parameters

Type	Name	Description
IPofReader	reader	The IPofReader from which to read the object's state.

Exceptions

Type	Condition
IOException	If an I/O error occurs.

ToString()

Return a human-readable description for this PresentFilter.

Declaration

public override string ToString()

Returns

Type	Description
string	A string description of the PresentFilter.

Overrides

object.ToString()

WriteExternal(IPofWriter)

Save the contents of a POF user type instance by writing its state using the specified IPofWriter object.

Declaration

public virtual void WriteExternal(IPofWriter writer)

Parameters

Type	Name	Description
IPofWriter	writer	The IPofWriter to which to write the object's state.

Exceptions

Type	Condition
IOException	If an I/O error occurs.

Implements

IEntryFilter

IFilter

IPortableObject

See Also

IsPresent