This class implements the logic for a striped hash multimap with logic that supports a (unique) map as a special case.

Synopsis

Declared in <bdlcc_stripedunorderedcontainerimpl.h>

template<
    class KEY,
    class VALUE,
    class HASH = bsl::hash<KEY>,
    class EQUAL = bsl::equal_to<KEY>>
class StripedUnorderedContainerImpl;

Type Aliases

Name

Description

EraseIfValuePredicate

An alias to a function meeting the following contract: ` bool eraseIfValuePredicate(const VALUE& value); // Return 'true' if the specified 'value' is to be removed from // the container, and 'false' otherwise. Note that this // functor can not change the values associated with 'value'. `

KVType

Value type of a bulk insert entry.

Node

Node in a bucket.

ReadOnlyVisitorFunction

An alias to a function meeting the following contract: ` bool visitorFunction(const VALUE& value, const KEY& key); // Visit the specified 'value' attribute associated with the // specified 'key'. Return 'true' if this function may be // called on additional elements, and 'false' otherwise (i.e., // if no other elements should be visited). Note that this // functor can not change the values associated with 'key' // and 'value'. `

VisitorFunction

An alias to a function meeting the following contract: ` bool visitorFunction(VALUE *value, const KEY& key); // Visit the specified 'value' attribute associated with the // specified 'key'. Return 'true' if this function may be // called on additional elements, and 'false' otherwise (i.e., // if no other elements should be visited). Note that this // functor can change the value associated with 'key'. `

Enums

Name

Description

Unnamed enum

Default sizing constants for this container.

Member Functions

Name

Description

StripedUnorderedContainerImpl [constructor]

Constructors

~StripedUnorderedContainerImpl [destructor]

Destroy this hash map. This method is not thread‐safe.

allocator

Return the allocator used by this hash map to supply memory. Note that if no allocator was supplied at construction the default allocator installed at that time is used.

bucketCount

Return the number of buckets in the array of buckets maintained by this hash map. Note that unless rehash is disabled, the value returned may be obsolete by the time it is received.

bucketIndex

Return the index of the bucket, in the array of buckets maintained by this hash map, where elements having the specified key are inserted. Note that unless rehash is disabled, the value returned may be obsolete at the time it is returned.

bucketSize

Return the number of elements contained in the bucket at the specified index in the array of buckets maintained by this hash map. The behavior is undefined unless 0 <= index < bucketCount().

canRehash

Return true if rehash is enabled and rehash is not in progress, and false otherwise.

clear

Remove all elements from this striped hash map. If rehash is in progress, block until it completes.

disableRehash

Prevent rehash until the enableRehash method is called.

empty

Return true if this hash map contains no elements, and false otherwise.

enableRehash

Allow rehash. If conditions warrant, rehash will be started by the next method call that observes the load factor is exceeded (see {Concurrent Rehash}). Note that calling maxLoadFactor(maxLoadFactor()) (i.e., setting the maximum load factor to its current value) will trigger a rehash if needed but otherwise does not change the hash map.

equalFunction

Return (a copy of) the key‐equality functor used by this hash map that returns true if two KEY objects have the same value, and false otherwise.

eraseAll

Erase from this hash map the elements having the specified key. Return the number of elements erased.

eraseAllIf

Erase from this hash map the elements having the specified key for which the specified predicate holds true. Return the number of elements erased.

eraseBulkAll

Erase from this hash map elements in this hash map having any of the values in the keys contained between the specified first (inclusive) and last (exclusive) random‐access iterators. The iterators provide read access to a sequence of KEY objects. All erasures are done by the calling thread and the order of erasure is not specified. Return the number of elements removed. The behavior is undefined unless first <= last. Note that the map may not have an element for every value in keys.

eraseBulkFirst

Erase from this hash map elements in this hash map having any of the values in the keys contained between the specified first (inclusive) and last (exclusive) random‐access iterators. The iterators provide read access to a sequence of KEY objects. If there are multiple elements for any key value, erase just the first such element found. All erasures are done by the calling thread and the order of erasure is not specified. Return the number of elements removed. The behavior is undefined unless first <= last. Note that the map may not have an element for every value in keys.

eraseFirst

Erase from this hash map the first element (of possibly many) found to the specified key. Return the number of elements erased. Note that method is more performant than eraseAll when there is one element having key.

eraseFirstIf

Erase from this hash map the first element with specified key (of possibly many) found, for which the specified predicate holds true. Return the number of elements erased.

getValue

getValue overloads

hashFunction

Return (a copy of) the unary hash functor used by this hash map to generate a hash value (of type std::size_t) for a KEY object.

insertAlways

insertAlways overloads

insertBulkAlways

Insert into this hash map elements having the key‐value pairs obtained between the specified first (inclusive) and last (exclusive) random‐access iterators. The iterators provide read access to a sequence of bsl::pair<KEY, VALUE> objects. All insertions are done by the calling thread and the order of insertion is not specified. The behavior is undefined unless first <= last.

insertBulkUnique

Insert into this hash map elements having the key‐value pairs obtained between the specified first (inclusive) and last (exclusive) random‐access iterators. The iterators provide read access to a sequence of bsl::pair<KEY, VALUE> objects. If an element having one of the keys already exists in this hash map, set the value attribute to the corresponding value from data. All insertions are done by the calling thread and the order of insertion is not specified. Return the number of elements inserted. The behavior is undefined unless first <= last.

insertUnique

insertUnique overloads

isRehashEnabled

Return true if rehash is enabled, or false otherwise.

loadFactor

Return the current quotient of the size of this hash map and the number of buckets. Note that the load factor is a measure of container "fullness"; that is, a high load factor typically implies many collisions (many elements landing in the same bucket) and that decreases performance.

maxLoadFactor

Return the maximum load factor allowed for this hash map. If an insert operation would cause the load factor to exceed the maxLoadFactor() and rehashing is enabled, then that insert increases the number of buckets and rehashes the elements of the container into that larger set of buckets.

numStripes

Return the number of stripes in the hash.

rehash

Recreate this hash map to one having at least the specified numBuckets. This operation is a no‐op if any of the following are true: 1) rehash is disabled; 2) numBuckets less or equals the current number of buckets. See {Rehash}.

setComputedValueAll

Serially invoke the specified visitor passing the specified key, and the address of the value of each element in this hash map having key. If key is not in the map, value will be default constructed. That is, for each (key, value) found, invoke: ` bool visitor(VALUE *value, const Key& key); ` If no element in the map has key, insert (key, VALUE()) and invoke visitor with value pointing to the defsult constructed value. Return the number of elements visited or the negation of that value if visitations stopped because visitor returned false. visitor, when invoked, has exclusive access (i.e., write access) to each element during each invocation. The behavior is undefined if hash map manipulators and getValue* methods are invoked from within visitor, as it may lead to a deadlock. Note that the setComputedValueFirst method is more performant than the when the hash map contains a single element for key. Also note that a return value of 0 implies that an element was inserted.

setComputedValueFirst

Invoke the specified visitor passing the specified key, and the address of the value attribute of the first element (of possibly many elements) found in this hash map having key. If key is not in the map, value will be default constructed. That is, for (key, value), invoke: ` bool visitor(VALUE *value, const Key& key); ` If no element in the map has key, insert (key, VALUE()) and invoke visitor with value pointing to the defsult constructed value. Return 1 if key was found and visitor returned true, 0 if key was not found, and ‐1 if key was found and visitor returned false. visitor, when invoked, has exclusive access (i.e., write access) to the element. The behavior is undefined if hash map manipulators and getValue* methods are invoked from within visitor, as it may lead to a deadlock. Note that the return value equals the number of elements inserted. Also note that, when there are multiple elements having key, the selection of "first" is implementation specific and subject to change. Also note that this method is more performant than the setComputedValueAll method when the hash map contains a single element for key. Also note that a return value of 0 implies that an element was inserted.

setValueAll

Set the value attribute of every element in this hash map having the specified key to the specified value. If no such such element exists, insert (key, value). Return the number of elements found with key. Note that if no elements were found, and a new value was inserted, 0 is returned.

setValueFirst

setValueFirst overloads

size

Return the current number of elements in this hash.

update

Serially call the specified visitor on each element (if one exists) in this hash map having the specified key until every such element has been updated or visitor returns false. That is, for (key, value), invoke: ` bool visitor(&value, key); ` Return the number of elements visited or the negation of that value if visitations stopped because visitor returned false. visitor has exclusive access (i.e., write access) to each element for duration of each invocation. The behavior is undefined if hash map manipulators and getValue* methods are invoked from within visitor, as it may lead to a deadlock.

visit

visit overloads

visitReadOnly

visitReadOnly overloads

Friends

Name

Description

BloombergLP::bdlcc::StripedUnorderedContainerImpl_LockElement

A mutex + support info; padded to cacheline size, one per stripe

BloombergLP::bdlcc::StripedUnorderedContainerImpl_TestUtil

This class implements a test utility that gives the test driver access to the lock / unlock method of the Read/Write mutex. Its purpose is to allow testing that the locking actually happens as planned.

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