com.hazelcast.core
Interface MultiMap<K,V>

All Superinterfaces:

BaseMultiMap<K,V>, DistributedObject

All Known Implementing Classes:

ClientMultiMapProxy, ObjectMultiMapProxy

public interface MultiMap<K,V>
extends BaseMultiMap<K,V>, DistributedObject

A specialized map whose keys can be associated with multiple values.

Gotchas:

• Methods -- including but not limited to get, containsKey, containsValue, remove, put, lock, and unlock -- do not use hashCode and equals implementations of the keys. Instead, they use hashCode and equals of the binary (serialized) forms of the objects.
• Methods -- including but not limited to get, remove, keySet, values, entrySet -- return a collection clone of the values. The collection is NOT backed by the map, so changes to the map are NOT reflected in the collection, and vice-versa.

Author:

oztalip

See Also:

IMap

Method Summary

String	addEntryListener(EntryListener<K,V> listener, boolean includeValue) Adds an entry listener for this multimap.
String	addEntryListener(EntryListener<K,V> listener, K key, boolean includeValue) Adds the specified entry listener for the specified key.
String	addLocalEntryListener(EntryListener<K,V> listener) Adds a local entry listener for this multimap.
<SuppliedValue,Result> Result	aggregate(Supplier<K,V,SuppliedValue> supplier, Aggregation<K,SuppliedValue,Result> aggregation) Executes a predefined aggregation on the multimaps data set.
<SuppliedValue,Result> Result	aggregate(Supplier<K,V,SuppliedValue> supplier, Aggregation<K,SuppliedValue,Result> aggregation, JobTracker jobTracker) Executes a predefined aggregation on the multimaps data set.
void	clear() Clears the multimap.
boolean	containsEntry(K key, V value) Returns whether the multimap contains the given key-value pair.
boolean	containsKey(K key) Returns whether the multimap contains an entry with the key.
boolean	containsValue(Object value) Returns whether the multimap contains an entry with the value.
Set<Map.Entry<K,V>>	entrySet() Returns the set of key-value pairs in the multimap.
void	forceUnlock(K key) Releases the lock for the specified key regardless of the lock owner.
Collection<V>	get(K key) Returns the collection of values associated with the key.
LocalMultiMapStats	getLocalMultiMapStats() Returns LocalMultiMapStats for this map.
String	getName() Returns the name of this multimap.
boolean	isLocked(K key) Checks the lock for the specified key.
Set<K>	keySet() Returns the set of keys in the multimap.
Set<K>	localKeySet() Returns the locally owned set of keys.
void	lock(K key) Acquires a lock for the specified key.
void	lock(K key, long leaseTime, TimeUnit timeUnit) Acquires the lock for the specified key for the specified lease time.
boolean	put(K key, V value) Stores a key-value pair in the multimap.
Collection<V>	remove(Object key) Removes all the entries with the given key.
boolean	remove(Object key, Object value) Removes the given key value pair from the multimap.
boolean	removeEntryListener(String registrationId) Removes the specified entry listener.
int	size() Returns the number of key-value pairs in the multimap.
boolean	tryLock(K key) Tries to acquire the lock for the specified key.
boolean	tryLock(K key, long time, TimeUnit timeunit) Tries to acquire the lock for the specified key.
void	unlock(K key) Releases the lock for the specified key.
int	valueCount(K key) Returns the number of values that match the given key in the multimap.
Collection<V>	values() Returns the collection of values in the multimap.

Methods inherited from interface com.hazelcast.core.DistributedObject

destroy, getId, getPartitionKey, getServiceName

Method Detail

getName

String getName()

Returns the name of this multimap.

Specified by:

getName in interface DistributedObject

Returns:

the name of this multimap

put

boolean put(K key,
            V value)

Stores a key-value pair in the multimap.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Specified by:

put in interface BaseMultiMap<K,V>

Parameters:

key - the key to be stored

value - the value to be stored

Returns:

true if size of the multimap is increased, false if the multimap already contains the key-value pair.

get

Collection<V> get(K key)

Returns the collection of values associated with the key.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Warning-2:

The collection is NOT backed by the map, so changes to the map are NOT reflected in the collection, and vice-versa.

Specified by:

get in interface BaseMultiMap<K,V>

Parameters:

key - the key whose associated values are to be returned

Returns:

the collection of the values associated with the key.

remove

boolean remove(Object key,
               Object value)

Removes the given key value pair from the multimap.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Specified by:

remove in interface BaseMultiMap<K,V>

Parameters:

key - the key of the entry to remove

value - the value of the entry to remove

Returns:

true if the size of the multimap changed after the remove operation, false otherwise.

remove

Collection<V> remove(Object key)

Removes all the entries with the given key.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Warning-2:

The collection is NOT backed by the map, so changes to the map are NOT reflected in the collection, and vice-versa.

Specified by:

remove in interface BaseMultiMap<K,V>

Parameters:

key - the key of the entries to remove

Returns:

the collection of removed values associated with the given key. The returned collection might be modifiable but it has no effect on the multimap.

localKeySet

Set<K> localKeySet()

Returns the locally owned set of keys.

Each key in this map is owned and managed by a specific member in the cluster.

Note that ownership of these keys might change over time so that key ownerships can be almost evenly distributed in the cluster.

Warning:

The set is NOT backed by the map, so changes to the map are NOT reflected in the set, and vice-versa.

Returns:

the locally owned keys

keySet

Set<K> keySet()

Returns the set of keys in the multimap.

Warning:

The set is NOT backed by the map, so changes to the map are NOT reflected in the set, and vice-versa.

Returns:

the set of keys in the multimap. The returned set might be modifiable but it has no effect on the multimap.

values

Collection<V> values()

Returns the collection of values in the multimap.

Warning:

The collection is NOT backed by the map, so changes to the map are NOT reflected in the collection, and vice-versa.

Returns:

the collection of values in the multimap. the returned collection might be modifiable but it has no effect on the multimap.

entrySet

Set<Map.Entry<K,V>> entrySet()

Returns the set of key-value pairs in the multimap.

Warning:

The set is NOT backed by the map, so changes to the map are NOT reflected in the set, and vice-versa.

Returns:

the set of key-value pairs in the multimap. The returned set might be modifiable but it has no effect on the multimap.

containsKey

boolean containsKey(K key)

Returns whether the multimap contains an entry with the key.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Parameters:

key - the key whose existence is checked.

Returns:

true if the multimap contains an entry with the key, false otherwise.

containsValue

boolean containsValue(Object value)

Returns whether the multimap contains an entry with the value.

Parameters:

value - the value whose existence is checked.

Returns:

true if the multimap contains an entry with the value, false otherwise.

containsEntry

boolean containsEntry(K key,
                      V value)

Returns whether the multimap contains the given key-value pair.

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in key's class.

Parameters:

key - the key whose existence is checked.

value - the value whose existence is checked.

Returns:

true if the multimap contains the key-value pair, false otherwise.

size

int size()

Returns the number of key-value pairs in the multimap.

Specified by:

size in interface BaseMultiMap<K,V>

Returns:

the number of key-value pairs in the multimap.

clear

void clear()

Clears the multimap. Removes all key-value pairs.

valueCount

int valueCount(K key)

Returns the number of values that match the given key in the multimap.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Specified by:

valueCount in interface BaseMultiMap<K,V>

Parameters:

key - the key whose values count is to be returned

Returns:

the number of values that match the given key in the multimap

addLocalEntryListener

String addLocalEntryListener(EntryListener<K,V> listener)

Adds a local entry listener for this multimap. The added listener will be only listening for the events (add/remove/update) of the locally owned entries.

Note that entries in distributed multimap are partitioned across the cluster members; each member owns and manages some portion of the entries. Owned entries are called local entries. This listener will be listening for the events of local entries. Let's say your cluster has member1 and member2. On member2 you added a local listener, and from member1, you call multimap.put(key2, value2). If the key2 is owned by member2, then the local listener will be notified for the add/update event. Also note that entries can migrate to other nodes for load balancing and/or membership change.

Parameters:

listener - entry listener for this multimap

Returns:

returns registration id for the entry listener

See Also:

localKeySet()

addEntryListener

String addEntryListener(EntryListener<K,V> listener,
                        boolean includeValue)

Adds an entry listener for this multimap. The listener will be notified for all multimap add/remove/update/evict events.

Parameters:

listener - entry listener for this multimap

includeValue - true if EntryEvent should contain the value, false otherwise

Returns:

returns registration id for the entry listener

removeEntryListener

boolean removeEntryListener(String registrationId)

Removes the specified entry listener. Returns silently if no such listener was added before.

Parameters:

registrationId - registration id of listener

Returns:

true if registration is removed, false otherwise

addEntryListener

String addEntryListener(EntryListener<K,V> listener,
                        K key,
                        boolean includeValue)

Adds the specified entry listener for the specified key. The listener will be notified for all add/remove/update/evict events for the specified key only.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Parameters:

listener - the entry listener

key - the key to listen to

includeValue - true if EntryEvent should contain the value, false otherwise

Returns:

returns registration id.

lock

void lock(K key)

Acquires a lock for the specified key.

If the lock is not available, then the current thread becomes disabled for thread scheduling purposes and lies dormant until the lock has been acquired.

The scope of the lock is for this multimap only. The acquired lock is only for the key in this multimap.

Locks are re-entrant, so if the key is locked N times, then it should be unlocked N times before another thread can acquire it.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Parameters:

key - the key to lock.

lock

void lock(K key,
          long leaseTime,
          TimeUnit timeUnit)

Acquires the lock for the specified key for the specified lease time.

After the lease time, the lock will be released.

If the lock is not available, then the current thread becomes disabled for thread scheduling purposes and lies dormant until the lock has been acquired.

Scope of the lock is for this map only. The acquired lock is only for the key in this map.

Locks are re-entrant, so if the key is locked N times, then it should be unlocked N times before another thread can acquire it.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Parameters:

key - the key to lock.

leaseTime - time to wait before releasing the lock.

timeUnit - unit of time for the lease time.

isLocked

boolean isLocked(K key)

Checks the lock for the specified key.

If the lock is acquired, this method returns true, else it returns false.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Parameters:

key - key to lock to be checked.

Returns:

true if the lock is acquired, false otherwise.

tryLock

boolean tryLock(K key)

Tries to acquire the lock for the specified key.

If the lock is not available, then the current thread does not wait and the method returns false immediately.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Parameters:

key - the key to lock.

Returns:

true if lock is acquired, false otherwise.

tryLock

boolean tryLock(K key,
                long time,
                TimeUnit timeunit)
                throws InterruptedException

Tries to acquire the lock for the specified key.

If the lock is not available, then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of two things happens:

• the lock is acquired by the current thread, or
• the specified waiting time elapses.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Parameters:

time - the maximum time to wait for the lock

timeunit - the time unit of the time argument

Returns:

true if the lock was acquired, false if the waiting time elapsed before the lock was acquired.

Throws:

InterruptedException

unlock

void unlock(K key)

Releases the lock for the specified key. It never blocks and returns immediately.

Warning:

This method uses hashCode and equals of the binary form of the key, not the actual implementations of hashCode and equals defined in the key's class.

Parameters:

key - the key to lock.

forceUnlock

void forceUnlock(K key)

Releases the lock for the specified key regardless of the lock owner. It always successfully unlocks the key, never blocks and returns immediately.

Warning:

This method uses hashCode and equals of binary form of the key, not the actual implementations of hashCode and equals defined in key's class.

Parameters:

key - key to lock.

getLocalMultiMapStats

LocalMultiMapStats getLocalMultiMapStats()

Returns LocalMultiMapStats for this map. LocalMultiMapStats is the statistics for the local portion of this distributed multi map and contains information such as ownedEntryCount backupEntryCount, lastUpdateTime, and lockedEntryCount.

Since this stats are only for the local portion of this multi map, if you need the cluster-wide MultiMapStats, then you need to get the LocalMapStats from all members of the cluster and combine them.

Returns:

this multimap's local statistics.

aggregate

<SuppliedValue,Result> Result aggregate(Supplier<K,V,SuppliedValue> supplier,
                                        Aggregation<K,SuppliedValue,Result> aggregation)

Executes a predefined aggregation on the multimaps data set. The Supplier is used to either select or to select and extract a (sub-)value. A predefined set of aggregations can be found in Aggregations.

Type Parameters:

SuppliedValue - the final type emitted from the supplier

Result - the resulting aggregation value type

Parameters:

supplier - the supplier to select and / or extract a (sub-)value from the multimap

aggregation - the aggregation that is being executed against the multimap

Returns:

Returns the aggregated value for the multimaps data set

aggregate

<SuppliedValue,Result> Result aggregate(Supplier<K,V,SuppliedValue> supplier,
                                        Aggregation<K,SuppliedValue,Result> aggregation,
                                        JobTracker jobTracker)

Executes a predefined aggregation on the multimaps data set. The Supplier is used to either select, or to select and extract, a (sub-)value. A predefined set of aggregations can be found in Aggregations.

Type Parameters:

SuppliedValue - the final type emitted from the supplier

Result - the resulting aggregation value type

Parameters:

supplier - the supplier to select and / or extract a (sub-)value from the multimap

aggregation - the aggregation that is being executed against the multimap

jobTracker - the JobTracker instance to execute the aggregation

Returns:

Returns the aggregated value