Oracle Coherence for C++ API: CompositeAggregator Class Reference

Detailed Description

CompositeAggregator provides an ability to execute a collection of aggregators against the same subset of the entries in an InvocableMap, resulting in a list of corresponding aggregation results.

The size of the returned list will always be equal to the length of the aggregators' array.

Author:

djl 2008.05.16

Public Types

typedef spec::Handle

Handle

CompositeAggregator Handle definition.

typedef spec::View

View

CompositeAggregator View definition.

typedef spec::Holder

Holder

CompositeAggregator Holder definition.

Public Member Functions

virtual Object::Holder

aggregate (Set::View vSetEntries)

Process a set of InvocableMap::Entry objects in order to produce an aggregated result.

Parameters:

vSetEntries

a Set of read-only InvocableMap::Entry objects to aggregate

Returns:: the aggregated result from processing the entries

virtual void

readExternal (PofReader::Handle hIn)

virtual void

writeExternal (PofWriter::Handle hOut) const

virtual bool

equals (Object::View v) const

virtual size32_t

hashCode () const

Return a hash code value for the Object.

This method is supported for the benefit of hash-based containers.

The general contract of hashCode is:

Whenever it is invoked on the same Object more than once during an execution of an application, the hashCode method must consistently return the same value, provided no information used in equals comparisons on the object is modified. This value need not remain consistent from one execution of an application to another execution of the same application.
If two Objects are equal according to the equals method, then calling the hashCode method on each of the two Objects must produce the same value.
It is not required that if two Objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct results. However, the programmer should be aware that producing distinct results for unequal objects may improve the performance of hash-based containers.

The default implementation is identity based.

Returns:: a hash code value for this Object

virtual void

toStream (std::ostream &out) const

Output a human-readable description of this Object to the given stream.

coherence::lang::operator<<(std::ostream, Object::View) is defined and will call into the toStream method, to output Objects. If a managed String object is desired, the COH_TO_STRING macro can be used to build up a String from streamable contents.

 Object::View vKey   = ...
 Object::View vValue = ...
 std::cout << vKey << " = " << vValue << std::endl;

 String::Handle hs = COH_TO_STRING(vKey << " = " << vValue);

Parameters:

out

the stream used to output the description

virtual ObjectArray::View

getAggregators () const

Determine the ValueExtractor whose values this aggregator is aggregating.

Static Public Member Functions

static
CompositeAggregator::Handle

create ()

Default constructor (necessary for the PortableObject interface).

static
CompositeAggregator::Handle

create (ObjectArray::View vaAggregator)

Create an instance of CompositeAggregator based on a specified array of coherence::util::InvocableMap::EntryAggregator.

Protected Attributes

MemberView< ObjectArray >

m_vaAggregator

The underlying EntryAggregator array.

Member Function Documentation

static CompositeAggregator::Handle create ( ObjectArray::View vaAggregator ) [static]

Create an instance of CompositeAggregator based on a specified array of coherence::util::InvocableMap::EntryAggregator.

If all the aggregators in the specified array are instances of coherence::util::InvocableMap::ParallelAwareAggregator then a parallel-aware instance of the CompositeAggregator will be created.
If at least one of the specified aggregator is not parallel-aware, then the resulting CompositeAggregator will not be parallel-aware and could be ill-suited for aggregations run against large partitioned caches.

Parameters:

vaAggregator

an array of EntryAggregator objects; must contain not less than two aggregators

virtual ObjectArray::View getAggregators ( ) const [virtual]

Determine the ValueExtractor whose values this aggregator is aggregating.

Returns:: the ValueExtractor used by this aggregator