Oracle® Fusion Middleware C++ API Reference for Oracle Coherence: WeakHashMap Class Reference

Detailed Description

WeakHashMap

That is the use an object as a key in the map will not prevent it from being destroyed if all other non-weak references to it are released.

The time at which the entry associated with the weak key is cleaned up is not guaranteed, it may live in the map for some time. While it is not safe to assume that the map will shrink to its absolute minimum at any point, it is safe to assume that given constant random key insertions the size of the map will initially grow and then stabilize as the keys are reclaimed.

Note: Iterating the entries may yield entries with reclaimed (NULL) keys.

Author:

mf 2008.05.27

Public Types

typedef spec::Handle

Handle

WeakHashMap Handle definition.

typedef spec::View

View

WeakHashMap View definition.

typedef spec::Holder

Holder

WeakHashMap Holder definition.

Public Member Functions

virtual void

compact ()

Cleanup any "garbage" entries in the map.

Protected Member Functions

WeakHashMap (size32_t cInitialBuckets=17, float32_t flLoadFactor=1.0F, float32_t flGrowthRate=3.0F)

Construct a thread-safe weak hash map using the specified settings.

WeakHashMap (const WeakHashMap &that)

Copy constructor.

virtual
SafeHashMap::Entry::Handle

instantiateEntry (Object::View vKey, Object::Holder ohValue, size32_t nHash)

Factory pattern, initialized with the specified valued.

Parameters:

	vKey	the associated key
	ohValue	the assocaited value
	nHash	the associated hash code

Returns:: a new instance of the Entry class (or a subclass thereof)

virtual
SafeHashMap::Entry::Handle

instantiateEntry (SafeHashMap::Entry::View vThat)

Factory pattern, instantiate an Entry that is either a deep or shalow copy.

Parameters:

	vEntry	the Entry to copy
	fDeep	whether to make a deep copy of the Entry or not

virtual void

grow ()

Resize the bucket array, rehashing all Entries.

virtual size32_t

shrink (size32_t iBucket, size32_t cEntries)

Shrink the specified bucket.

Classes

class

Entry

A map entry (key-value pair). More...

Constructor & Destructor Documentation

WeakHashMap	(	size32_t	cInitialBuckets = `17`,
		float32_t	flLoadFactor = `1.0F`,
		float32_t	flGrowthRate = `3.0F`
	)			`[protected]`

Construct a thread-safe weak hash map using the specified settings.

Parameters:

	cInitialBuckets	the initial number of hash buckets, 0 < n
	flLoadFactor	the acceptable load factor before resizing occurs, 0 < n, such that a load factor of 1.0 causes resizing when the number of entries exceeds the number of buckets
	flGrowthRate	the rate of bucket growth when a resize occurs, 0 < n, such that a growth rate of 1.0 will double the number of buckets: bucketcount = bucketcount * (1 + growthrate)

Member Function Documentation

virtual size32_t shrink	(	size32_t	iBucket,
		size32_t	cEntries
	)			`[protected, virtual]`

Shrink the specified bucket.

Parameters:

	iBucket	the bucket to shrink
	cEntries	the maximum number of entries to shrink by

Returns:: the number of entries removed