Package io.vertx.core.shareddata

Interface SharedData

public interface SharedData

Shared data allows you to share data safely between different parts of your application in a safe way.

Shared data provides:

• synchronous shared maps (local)
• asynchronous maps (local or cluster-wide)
• asynchronous locks (local or cluster-wide)
• asynchronous counters (local or cluster-wide)

WARNING: In clustered mode, asynchronous maps/locks/counters rely on distributed data structures provided by the cluster manager. Beware that the latency relative to asynchronous maps/locks/counters operations can be much higher in clustered than in local mode.

Please see the documentation for more information.

Author:

Tim Fox

Method Summary

Modifier and Type	Method	Description
<K,V> Future<AsyncMap<K,V>>	getAsyncMap(String name)	Get the AsyncMap with the specified name.
<K,V> Future<AsyncMap<K,V>>	getClusterWideMap(String name)	Get the cluster wide map with the specified name.
Future<Counter>	getCounter(String name)	Get an asynchronous counter.
<K,V> Future<AsyncMap<K,V>>	getLocalAsyncMap(String name)	Get the AsyncMap with the specified name.
Future<Counter>	getLocalCounter(String name)	Get an asynchronous local counter.
Future<Lock>	getLocalLock(String name)	Get an asynchronous local lock with the specified name.
Future<Lock>	getLocalLockWithTimeout(String name, long timeout)	Like getLocalLock(String) but specifying a timeout.
<K,V> LocalMap<K,V>	getLocalMap(String name)	Return a LocalMap with the specific name.
Future<Lock>	getLock(String name)	Get an asynchronous lock with the specified name.
Future<Lock>	getLockWithTimeout(String name, long timeout)	Like getLock(String) but specifying a timeout.
default <T> Future<T>	withLocalLock(String name, long timeout, java.util.function.Supplier<Future<T>> block)	Like withLocalLock(String, Supplier) but specifying a timeout.
default <T> Future<T>	withLocalLock(String name, java.util.function.Supplier<Future<T>> block)	Get an asynchronous local lock with the specified name.
default <T> Future<T>	withLock(String name, long timeout, java.util.function.Supplier<Future<T>> block)	Like withLock(String, Supplier) but specifying a timeout.
default <T> Future<T>	withLock(String name, java.util.function.Supplier<Future<T>> block)	Get an asynchronous lock with the specified name.

Method Detail

getClusterWideMap

<K,V> Future<AsyncMap<K,V>> getClusterWideMap(String name)

Get the cluster wide map with the specified name. The map is accessible to all nodes in the cluster and data put into the map from any node is visible to to any other node.

Parameters:

name - the name of the map

Returns:

a future notified with the map

Throws:

IllegalStateException - if the parent Vertx instance is not clustered

getAsyncMap

<K,V> Future<AsyncMap<K,V>> getAsyncMap(String name)

Get the AsyncMap with the specified name. When clustered, the map is accessible to all nodes in the cluster and data put into the map from any node is visible to to any other node.

WARNING: In clustered mode, asynchronous shared maps rely on distributed data structures provided by the cluster manager. Beware that the latency relative to asynchronous shared maps operations can be much higher in clustered than in local mode.

Parameters:

name - the name of the map

Returns:

a future notified with the map

getLocalAsyncMap

<K,V> Future<AsyncMap<K,V>> getLocalAsyncMap(String name)

Get the AsyncMap with the specified name.

When clustered, the map is NOT accessible to all nodes in the cluster. Only the instance which created the map can put and retrieve data from this map.

Parameters:

name - the name of the map

Returns:

a future notified with the map

getLock

Future<Lock> getLock(String name)

Get an asynchronous lock with the specified name. The returned future will be completed with the lock when it is available.

In general lock acquision is unordered, so that sequential attempts to acquire a lock, even from a single thread, can happen in non-sequential order.

Parameters:

name - the name of the lock

Returns:

a future notified with the lock

getLockWithTimeout

Future<Lock> getLockWithTimeout(String name,
                                long timeout)

Like getLock(String) but specifying a timeout. If the lock is not obtained within the timeout the returned future is failed.

In general lock acquision is unordered, so that sequential attempts to acquire a lock, even from a single thread, can happen in non-sequential order.

Parameters:

name - the name of the lock

timeout - the timeout in ms

Returns:

a future notified with the lock

withLock

default <T> Future<T> withLock(String name,
                               java.util.function.Supplier<Future<T>> block)

Get an asynchronous lock with the specified name.

When the block is called, the lock is already acquired, it will be released when the Future<T> returned by the block completes.

When the block fails, the lock is released and the returned future is failed with the cause of the failure.

In general lock acquision is unordered, so that sequential attempts to acquire a lock, even from a single thread, can happen in non-sequential order.

Parameters:

name - the name of the lock

Returns:

the future returned by the block

withLock

default <T> Future<T> withLock(String name,
                               long timeout,
                               java.util.function.Supplier<Future<T>> block)

Like withLock(String, Supplier) but specifying a timeout. If the lock is not obtained within the timeout the returned future is failed.

Parameters:

name - the name of the lock

timeout - the timeout in ms

block - the code block called after lock acquisition

Returns:

the future returned by the block

getLocalLock

Future<Lock> getLocalLock(String name)

Get an asynchronous local lock with the specified name. The returned future will be completed with the lock when it is available.

In general lock acquision is unordered, so that sequential attempts to acquire a lock, even from a single thread, can happen in non-sequential order.

Parameters:

name - the name of the lock

Returns:

a future notified with the lock

getLocalLockWithTimeout

Future<Lock> getLocalLockWithTimeout(String name,
                                     long timeout)

Like getLocalLock(String) but specifying a timeout. If the lock is not obtained within the timeout the returned future is failed.

In general lock acquision is unordered, so that sequential attempts to acquire a lock, even from a single thread, can happen in non-sequential order.

Parameters:

name - the name of the lock

timeout - the timeout in ms

Returns:

a future notified with the lock

withLocalLock

default <T> Future<T> withLocalLock(String name,
                                    java.util.function.Supplier<Future<T>> block)

Get an asynchronous local lock with the specified name.

When the block is called, the lock is already acquired, it will be released when the Future<T> returned by the block completes.

When the block fails, the lock is released and the returned future is failed with the cause of the failure.

In general lock acquision is unordered, so that sequential attempts to acquire a lock, even from a single thread, can happen in non-sequential order.

Parameters:

name - the name of the lock

Returns:

the future returned by the block

withLocalLock

default <T> Future<T> withLocalLock(String name,
                                    long timeout,
                                    java.util.function.Supplier<Future<T>> block)

Like withLocalLock(String, Supplier) but specifying a timeout. If the lock is not obtained within the timeout the returned future is failed.

Parameters:

name - the name of the lock

timeout - the timeout in ms

block - the code block called after lock acquisition

Returns:

the future returned by the block

getCounter

Future<Counter> getCounter(String name)

Get an asynchronous counter. The counter will be passed to the handler.

Parameters:

name - the name of the counter.

Returns:

a future notified with the counter

getLocalCounter

Future<Counter> getLocalCounter(String name)

Get an asynchronous local counter. The counter will be passed to the handler.

Parameters:

name - the name of the counter.

Returns:

a future notified with the counter

getLocalMap

<K,V> LocalMap<K,V> getLocalMap(String name)

Return a LocalMap with the specific name.

Parameters:

name - the name of the map

Returns:

the map