BloombergLP::bdlcc::StripedUnorderedMultiMap

Fully thread‐safe striped hash multimap from KEY to VALUE.

Synopsis

Declared in <bdlcc_stripedunorderedmultimap.h>

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

Description

This class template defines a fully thread‐safe container that provides a mapping from keys (of template parameter type KEY) to their associated mapped values (of template parameter type VALUE).

The buckets of this hash map are guarded by numStripes reader‐writer locks, a value specified on construction. Partitioning the buckets among several locks allows greater overall concurrency than a bsl::unordered_multimap object guarded by a single lock.

The interface is inspired by, but not identical to that of bsl::unordered_multimap. Notably absent are iterators, which are of limited practicality in the typical use case because they are readily invalidated when the map population is open to modification by multiple threads.

Type Aliases

Name

Description

EraseIfValuePredicate

Alias for a predicate that selects values to erase.

KVType

Value type of a bulk insert entry.

ReadOnlyVisitorFunction

Alias for a read‐only visitor over element values.

VisitorFunction

Alias for a visitor that may modify element values.

Enums

Name

Description

Unnamed enum

Default sizing constants for this multimap.

Member Functions

Name

Description

StripedUnorderedMultiMap [constructor]

Constructors

allocator

Return the allocator used by this hash map to supply memory.

bucketCount

Return the number of buckets maintained by this hash map.

bucketIndex

Return the bucket index where elements with key are inserted.

bucketSize

Return the number of elements in the bucket at the specified index.

clear

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

disableRehash

Prevent future rehash until enableRehash is called.

empty

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

enableRehash

Allow rehashing to resume when the load factor is exceeded.

equalFunction

Return a copy of the key‐equality functor used by this hash map.

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 all elements whose keys fall in [first, last)].

eraseFirst

Erase the first element found with the specified key.

eraseFirstIf

Erase the first element with key for which predicate is true.

getValueAll

getValueAll overloads

getValueFirst

Load into *value the first value found for the specified key.

hashFunction

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

insert

insert overloads

insertBulk

Insert key‐value pairs from the range [first, last)].

isRehashEnabled

Return true if rehash is enabled, or false otherwise.

loadFactor

Return the current size divided by the number of buckets.

maxLoadFactor

Return the maximum load factor allowed for this hash map.

numStripes

Return the number of stripes in the hash.