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).
Declared in <bdlcc_stripedunorderedmultimap.h>
template<
class KEY,
class VALUE,
class HASH = bsl::hash<KEY>,
class EQUAL = bsl::equal_to<KEY>>
class StripedUnorderedMultiMap;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.
| Name | Description |
|---|---|
EraseIfValuePredicate | An alias to a function meeting the following contract: ` /// 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. bool eraseIfValuePredicate(const VALUE& value); ` |
KVType | Value type of a bulk insert entry. |
ReadOnlyVisitorFunction | An alias to a function meeting the following contract: ` /// 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. bool readOnlyVisitorFunction(const VALUE& value, const KEY& key); ` |
VisitorFunction | An alias to a function meeting the following contract: ` /// 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. bool visitorFunction(VALUE *value, const KEY& key); ` |
| Name | Description |
|---|---|
Unnamed enum | Default sizing constants for this multimap. |
| Name | Description |
|---|---|
StripedUnorderedMultiMap [constructor] | Constructors |
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(). Note that unless rehash is disabled the value returned may be obsolete by the time it is returned. |
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 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. The returned function will return 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. |
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 (of possibly many) with specified key found, for which the specified predicate holds true. Return the number of elements erased. |
getValueAll | getValueAll overloads |
getValueFirst | Load, into the specified *value, the value attribute of the first element found in this hash map having the specified key. Return 1 on success, and 0 if key does not exist in this hash map. Note that the return value equals the number of values returned. |
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 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. |
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. See {Rehash Control}. |
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. See {Rehash Control}. |
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 default 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 default 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 map. |
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 |