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

    All Methods Instance Methods Abstract Methods Default Methods
    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, Supplier<Future<T>> block)` | Like `withLocalLock(String, Supplier)` but specifying a timeout.
    `default <T> Future<T>` | `withLocalLock​(String name, Supplier<Future<T>> block)` | Get an asynchronous local lock with the specified name.
    `default <T> Future<T>` | `withLock​(String name, long timeout, Supplier<Future<T>> block)` | Like `withLock(String, Supplier)` but specifying a timeout.
    `default <T> Future<T>` | `withLock​(String name, 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,
                                         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,
                                         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,
                                              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,
                                              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