bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL > Class Template Reference

#include <bdlcc_stripedunorderedmap.h>

Public Types
enum	{ k_DEFAULT_NUM_BUCKETS = 16 , k_DEFAULT_NUM_STRIPES = 4 }
typedef bsl::pair< KEY, VALUE >	KVType
	Value type of a bulk insert entry.
typedef bsl::function< bool(const VALUE &)>	EraseIfValuePredicate
typedef bsl::function< bool(VALUE *, const KEY &)>	VisitorFunction
typedef bsl::function< bool(const VALUE &, const KEY &)>	ReadOnlyVisitorFunction

Public Member Functions
	StripedUnorderedMap (bsl::size_t numInitialBuckets=k_DEFAULT_NUM_BUCKETS, bsl::size_t numStripes=k_DEFAULT_NUM_STRIPES, bslma::Allocator *basicAllocator=0)
	StripedUnorderedMap (bslma::Allocator *basicAllocator)
	~StripedUnorderedMap ()=default
	Destroy this hash map.
void	clear ()
void	disableRehash ()
	Prevent future rehash until enableRehash is called.
void	enableRehash ()
bsl::size_t	erase (const KEY &key)
template<class RANDOM_ITER >
bsl::size_t	eraseBulk (RANDOM_ITER first, RANDOM_ITER last)
bsl::size_t	eraseIf (const KEY &key, const EraseIfValuePredicate &predicate)
bsl::size_t	insert (const KEY &key, const VALUE &value)
bsl::size_t	insert (const KEY &key, bslmf::MovableRef< VALUE > value)
template<class RANDOM_ITER >
bsl::size_t	insertBulk (RANDOM_ITER first, RANDOM_ITER last)
void	maxLoadFactor (float newMaxLoadFactor)
void	rehash (bsl::size_t numBuckets)
int	setComputedValue (const KEY &key, const VisitorFunction &visitor)
bsl::size_t	setValue (const KEY &key, const VALUE &value)
bsl::size_t	setValue (const KEY &key, bslmf::MovableRef< VALUE > value)
int	update (const KEY &key, const VisitorFunction &visitor)
int	visit (const VisitorFunction &visitor)
int	visit (const KEY &key, const VisitorFunction &visitor)
bsl::size_t	bucketCount () const
bsl::size_t	bucketIndex (const KEY &key) const
bsl::size_t	bucketSize (bsl::size_t index) const
bool	empty () const
EQUAL	equalFunction () const
bsl::size_t	getValue (VALUE *value, const KEY &key) const
HASH	hashFunction () const
bool	isRehashEnabled () const
	Return true if rehash is enabled, or false otherwise.
float	loadFactor () const
float	maxLoadFactor () const
bsl::size_t	numStripes () const
	Return the number of stripes in the hash.
int	visitReadOnly (const ReadOnlyVisitorFunction &visitor) const
int	visitReadOnly (const KEY &key, const ReadOnlyVisitorFunction &visitor) const
bsl::size_t	size () const
	Return the current number of elements in this hash map.
bslma::Allocator *	allocator () const

Detailed Description

template<class KEY, class VALUE, class HASH = bsl::hash<KEY>, class EQUAL = bsl::equal_to<KEY>>
class bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >

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_map object guarded by a single lock.

The interface is inspired by, but not identical to that of bsl::unordered_map. 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.

See bdlcc_stripedunorderedmap

Member Typedef Documentation

EraseIfValuePredicate

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

typedef bsl::function<bool(const VALUE&)> bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::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

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

typedef bsl::pair<KEY, VALUE> bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::KVType

ReadOnlyVisitorFunction

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

typedef bsl::function<bool (const VALUE&, const KEY&)> bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::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 value associated with `key`
/// and `value`.
bool visitorFunction(const VALUE& value, const KEY& key);

VisitorFunction

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

typedef bsl::function<bool (VALUE *, const KEY&)> bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::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);

Member Enumeration Documentation

anonymous enum

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

anonymous enum

Enumerator
k_DEFAULT_NUM_BUCKETS
k_DEFAULT_NUM_STRIPES

Constructor & Destructor Documentation

StripedUnorderedMap() [1/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::StripedUnorderedMap ( bsl::size_t  numInitialBuckets = k_DEFAULT_NUM_BUCKETS, bsl::size_t  numStripes = k_DEFAULT_NUM_STRIPES, bslma::Allocator *  basicAllocator = 0  )

inlineexplicit

StripedUnorderedMap() [2/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::StripedUnorderedMap ( bslma::Allocator *  basicAllocator )

inlineexplicit

Create an empty StripedUnorderedMap object, a fully thread-safe hash map where access is partitioned into "stripes" (a group of buckets protected a reader-writer mutex). Optionally specify numInitialBuckets and numStripes which define the minimum number of buckets and the (fixed) number of stripes in this map. Optionally specify a basicAllocator used to supply memory. If basicAllocator is 0, the currently installed default allocator is used. The hash map has rehash enabled. Note that the number of stripes will not change after construction, but the number of buckets may (unless rehashing is disabled via disableRehash).

~StripedUnorderedMap()

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

bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::~StripedUnorderedMap ( )

default

Member Function Documentation

allocator()

template<class KEY , class VALUE , class HASH , class EQUAL >

bslma::Allocator * bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::allocator ( ) const

inline

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()

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::bucketCount ( ) const

inline

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()

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::bucketIndex ( const KEY &  key ) const

inline

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()

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::bucketSize ( bsl::size_t  index ) const

inline

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()

template<class KEY , class VALUE , class HASH , class EQUAL >

void bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::clear ( )

inline

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

disableRehash()

template<class KEY , class VALUE , class HASH , class EQUAL >

void bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::disableRehash ( )

inline

empty()

template<class KEY , class VALUE , class HASH , class EQUAL >

bool bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::empty ( ) const

inline

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

enableRehash()

template<class KEY , class VALUE , class HASH , class EQUAL >

void bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::enableRehash ( )

inline

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()

template<class KEY , class VALUE , class HASH , class EQUAL >

EQUAL bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::equalFunction ( ) const

inline

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.

erase()

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::erase ( const KEY &  key )

inline

Erase from this hash map the element having the specified key. Return 1 on success and 0 if key does not exist. Note that the returned value equals the number of elements removed.

eraseBulk()

template<class KEY , class VALUE , class HASH , class EQUAL >

template<class RANDOM_ITER >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::eraseBulk ( RANDOM_ITER  first, RANDOM_ITER  last  )

inline

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.

eraseIf()

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::eraseIf ( const KEY &  key, const EraseIfValuePredicate &  predicate  )

inline

Remove from this hash map the element, if any, having the specified key, where specified predicate holds true. Return the number of elements erased.

getValue()

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::getValue ( VALUE *  value, const KEY &  key  ) const

inline

Load, into the specified *value, the value attribute of the element 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()

template<class KEY , class VALUE , class HASH , class EQUAL >

HASH bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::hashFunction ( ) const

inline

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() [1/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::insert ( const KEY &  key, bslmf::MovableRef< VALUE >  value  )

inline

Insert into this hash map an element having the specified key and the specified move-insertable value. If key already exists in this hash map, the value attribute of that element is set to value. Return 1 if an element is inserted, and 0 if an existing element is updated. The value object is left in a valid but unspecified state. If value is allocator-enabled and allocator() != value.allocator() this operation may cost as much as a copy. Note that the return value equals the number of elements inserted.

insert() [2/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::insert ( const KEY &  key, const VALUE &  value  )

inline

Insert into this hash map an element having the specified key and value. If key already exists in this hash map, the value attribute of that element is set to value. Return 1 if an element is inserted, and 0 if an existing element is updated. Note that the return value equals the number of elements inserted.

insertBulk()

template<class KEY , class VALUE , class HASH , class EQUAL >

template<class RANDOM_ITER >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::insertBulk ( RANDOM_ITER  first, RANDOM_ITER  last  )

inline

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.

isRehashEnabled()

template<class KEY , class VALUE , class HASH , class EQUAL >

bool bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::isRehashEnabled ( ) const

inline

loadFactor()

template<class KEY , class VALUE , class HASH , class EQUAL >

float bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::loadFactor ( ) const

inline

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() [1/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

float bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::maxLoadFactor ( ) const

inline

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}.

maxLoadFactor() [2/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

void bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::maxLoadFactor ( float  newMaxLoadFactor )

inline

Set the maximum load factor of this unordered map to the specified newMaxLoadFactor. If newMaxLoadFactor < loadFactor(), this operation will cause an immediate rehash; otherwise, this operation has a constant-time cost. The rehash will increase the number of buckets by a power of 2. The behavior is undefined unless 0 < newMaxLoadFactor.

numStripes()

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::numStripes ( ) const

inline

rehash()

template<class KEY , class VALUE , class HASH , class EQUAL >

void bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::rehash ( bsl::size_t  numBuckets )

inline

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}.

setComputedValue()

template<class KEY , class VALUE , class HASH , class EQUAL >

int bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::setComputedValue ( const KEY &  key, const VisitorFunction &  visitor  )

inline

Invoke the specified visitor on the value associated with the specified key. The visitor will be passed the address of the value, and key. If key is not in the map, value will be default constructed. That is, visitor must be invocable with the VisitorFunction signature:

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 found having key. Also note that a return value of 0 implies that an element was inserted.

setValue() [1/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::setValue ( const KEY &  key, bslmf::MovableRef< VALUE >  value  )

inline

Set the value attribute of the element in this hash map having the specified key to the specified move-insertable value. If no such such element exists, insert (key, value). Return 1 if key was found, and 0 otherwise. The value object is left in a valid but unspecified state. If value is allocator-enabled and allocator() != value.allocator() this operation may cost as much as a copy. Note that the return value equals the number of elements found having key.

setValue() [2/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::setValue ( const KEY &  key, const VALUE &  value  )

inline

Set the value attribute of the element in this hash map having the specified key to the specified value. If no such such element exists, insert (key, value). Return 1 if key was found, and 0 otherwise. Note that the return value equals the number of elements found having key.

size()

template<class KEY , class VALUE , class HASH , class EQUAL >

bsl::size_t bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::size ( ) const

inline

update()

template<class KEY , class VALUE , class HASH , class EQUAL >

int bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::update ( const KEY &  key, const VisitorFunction &  visitor  )

inline

Deprecated:

Use visit(key, visitor) instead.

Call the specified visitor with the element (if one exists) in this hash map having the specified key. That is:

bool visitor(&value, key);

Return the number of elements updated or -1 if visitor returned false. visitor has exclusive access (i.e., write access) the element for during its 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() [1/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

int bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::visit ( const KEY &  key, const VisitorFunction &  visitor  )

inline

Call the specified visitor with the element (if one exists) in this hash map having the specified key. That is:

bool visitor(&value, key);

Return the number of elements updated or -1 if visitor returned false. visitor has exclusive access (i.e., write access) the element for during its 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() [2/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

int bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::visit ( const VisitorFunction &  visitor )

inline

Call the specified visitor (in an unspecified order) on all elements in this hash table until each such element has been visited 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. Every element present in this hash map at the time visit is invoked will be visited unless it is removed before visitor is called for that element. Each visitation is done by the calling thread and the order of visitation is not specified. Elements inserted during the execution of visit may or may not be visited. 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 visitor can change the value of the visited elements.

visitReadOnly() [1/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

int bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::visitReadOnly ( const KEY &  key, const ReadOnlyVisitorFunction &  visitor  ) const

inline

Call the specified visitor on element (if one exists) in this hash map having the specified key. That is, for (key, value), invoke:

bool visitor(value, key);

Return the number of elements visited or -1 if visitor returned false. visitor has read-only access to each element for duration of each invocation. The behavior is undefined if hash map manipulators are invoked from within visitor, as it may lead to a deadlock.

visitReadOnly() [2/2]

template<class KEY , class VALUE , class HASH , class EQUAL >

int bdlcc::StripedUnorderedMap< KEY, VALUE, HASH, EQUAL >::visitReadOnly ( const ReadOnlyVisitorFunction &  visitor ) const

inline

Call the specified visitor (in an unspecified order) on all elements in this hash table until each such element has been visited 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 read-only access to each element for duration of each invocation. Every element present in this hash map at the time visit is invoked will be visited unless it is removed before visitor is called for that element. Each visitation is done by the calling thread and the order of visitation is not specified. The behavior is undefined if hash map manipulators are invoked from within visitor, as it may lead to a deadlock. Note that visitor can not change the value of the visited elements.

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The documentation for this class was generated from the following file:

• bdlcc_stripedunorderedmap.h