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Oracle® Coherence Java API Reference Release 12.1.2.0.3 E26043-02 |
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java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.net.AbstractPriorityTask
com.tangosol.util.filter.PriorityFilter
public class PriorityFilter
PriorityFilter is used to explicitly control the scheduling priority and timeouts for execution of filter-based methods.
For example, let's assume that there is a cache that belongs to a partitioned cache service configured with a request-timeout and task-timeout of 5 seconds. Also assume that we are willing to wait longer for a particular rarely executed parallel query that does not employ any indexes. Then we could override the default timeout values by using the PriorityFilter as follows:
EqualsFilter filterStandard = new LikeFilter("getComments", "%fail%"); PriorityFilter filterPriority = new PriorityFilter(filterStandard); filterPriority.setExecutionTimeoutMillis(PriorityTask.TIMEOUT_NONE); filterPriority.setRequestTimeoutMillis(PriorityTask.TIMEOUT_NONE); Set setEntries = cache.entrySet(filterPriority);
This is an advanced feature which should be used judiciously.
Field Summary |
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Fields inherited from interface com.tangosol.net.PriorityTask |
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SCHEDULE_FIRST, SCHEDULE_IMMEDIATE, SCHEDULE_STANDARD, TIMEOUT_DEFAULT, TIMEOUT_NONE |
Constructor Summary | |
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PriorityFilter() Default constructor (necessary for the ExternalizableLite interface). |
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PriorityFilter(IndexAwareFilter filter) Construct a PriorityFilter. |
Method Summary | |
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Filter |
applyIndex(java.util.Map mapIndexes, java.util.Set setKeys) Filter remaining keys using a Map of available indexes. |
int |
calculateEffectiveness(java.util.Map mapIndexes, java.util.Set setKeys) Given a Map of available indexes, determine if this IndexAwareFilter can use any of the indexes to assist in its processing, and if so, determine how effective the use of that index would be. |
boolean |
evaluate(java.lang.Object o) Apply the test to the object. |
boolean |
evaluateEntry(java.util.Map.Entry entry) Apply the test to a Map Entry. |
IndexAwareFilter |
getFilter() Obtain the underlying filter. |
void |
readExternal(java.io.DataInput in) Restore the contents of this object by loading the object's state from the passed DataInput object. |
void |
readExternal(PofReader in) Restore the contents of a user type instance by reading its state using the specified PofReader object. |
java.lang.String |
toString() Return a human-readable description for this Filter. |
void |
writeExternal(java.io.DataOutput out) Save the contents of this object by storing the object's state into the passed DataOutput object. |
void |
writeExternal(PofWriter out) Save the contents of a POF user type instance by writing its state using the specified PofWriter object. |
Methods inherited from class com.tangosol.net.AbstractPriorityTask |
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getExecutionTimeoutMillis, getRequestTimeoutMillis, getSchedulingPriority, runCanceled, setExecutionTimeoutMillis, setRequestTimeoutMillis, setSchedulingPriority |
Methods inherited from class com.tangosol.util.BitHelper |
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countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString |
Constructor Detail |
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public PriorityFilter()
public PriorityFilter(IndexAwareFilter filter)
filter
- the filter wrapped by this PriorityFilterMethod Detail |
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public boolean evaluate(java.lang.Object o)
evaluate
in interface Filter
o
- the object to testpublic boolean evaluateEntry(java.util.Map.Entry entry)
evaluateEntry
in interface EntryFilter
entry
- the Map Entry to evaluate; never nullpublic int calculateEffectiveness(java.util.Map mapIndexes, java.util.Set setKeys)
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 keySet.size() * <evaluation cost> then a user could avoid using the index and iterate through the keySet calling evaluate rather then applyIndex.
calculateEffectiveness
in interface IndexAwareFilter
mapIndexes
- the available MapIndex
objects keyed by the related ValueExtractor; read-onlysetKeys
- the set of keys that will be filtered; read-onlypublic Filter applyIndex(java.util.Map mapIndexes, java.util.Set setKeys)
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 EntryFilter
) 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.
applyIndex
in interface IndexAwareFilter
mapIndexes
- the available MapIndex
objects keyed by the related ValueExtractor; read-onlysetKeys
- the mutable set of keys that remain to be filteredFilter
object (which may be an EntryFilter
) that can be used to process the remaining keys, or null if no additional filter processing is necessarypublic IndexAwareFilter getFilter()
public java.lang.String toString()
public void readExternal(java.io.DataInput in) throws java.io.IOException
readExternal
in interface ExternalizableLite
readExternal
in class AbstractPriorityTask
in
- the DataInput stream to read data from in order to restore the state of this objectjava.io.IOException
- if an I/O exception occursjava.io.NotActiveException
- if the object is not in its initial state, and therefore cannot be deserialized intopublic void writeExternal(java.io.DataOutput out) throws java.io.IOException
writeExternal
in interface ExternalizableLite
writeExternal
in class AbstractPriorityTask
out
- the DataOutput stream to write the state of this object tojava.io.IOException
- if an I/O exception occurspublic void readExternal(PofReader in) throws java.io.IOException
The AbstractPriorityTask implementation reserves property indexes 0 - 9.
This implementation reserves property index 10.
readExternal
in interface PortableObject
readExternal
in class AbstractPriorityTask
in
- the PofReader from which to read the object's statejava.io.IOException
- if an I/O error occurspublic void writeExternal(PofWriter out) throws java.io.IOException
The AbstractPriorityTask implementation reserves property indexes 0 - 9.
This implementation reserves property index 10.
writeExternal
in interface PortableObject
writeExternal
in class AbstractPriorityTask
out
- the PofWriter to which to write the object's statejava.io.IOException
- if an I/O error occurs
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Oracle® Coherence Java API Reference Release 12.1.2.0.3 E26043-02 |
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