com.hazelcast.concurrent.semaphore

## Class SemaphoreService

- java.lang.Object
- - com.hazelcast.concurrent.semaphore.SemaphoreService

- All Implemented Interfaces:
    ClientAwareService, ManagedService, MembershipAwareService, MigrationAwareService, QuorumAwareService, RemoteService

      public class SemaphoreService
      extends Object
      implements ManagedService, MigrationAwareService, MembershipAwareService, RemoteService, ClientAwareService, QuorumAwareService

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static String` | `SERVICE_NAME`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `SemaphoreService(NodeEngine nodeEngine)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `beforeMigration(PartitionMigrationEvent partitionMigrationEvent)` Called before migration process starts, on both source and destination members.
    `void` | `clientDisconnected(String clientUuid)` Invoked when a client disconnects from a member.
    `void` | `commitMigration(PartitionMigrationEvent event)` Commits the migration process for this service, on both source and destination members.
    `boolean` | `containsSemaphore(String name)`
    `SemaphoreProxy` | `createDistributedObject(String objectId)` Creates a distributed object.
    `void` | `destroyDistributedObject(String objectId)` Destroys a distributed object.
    `String` | `getQuorumName(String name)` Gets the name of the quorum associated with specified operation name.
    `SemaphoreContainer` | `getSemaphoreContainer(String name)`
    `void` | `init(NodeEngine nodeEngine, Properties properties)` Initializes this service.
    `void` | `insertMigrationData(Map<String,SemaphoreContainer> migrationData)`
    `void` | `memberAdded(MembershipServiceEvent event)` Invoked when a new member is added to the cluster.
    `void` | `memberAttributeChanged(MemberAttributeServiceEvent event)` Invoked when a member attribute is changed.
    `void` | `memberRemoved(MembershipServiceEvent event)` Invoked when an existing member leaves the cluster.
    `Operation` | `prepareReplicationOperation(PartitionReplicationEvent event)` Returns an operation to replicate service data and/or state for a specific partition replica on another cluster member.
    `void` | `reset()` Resets this service back to its initial state.
    `void` | `rollbackMigration(PartitionMigrationEvent event)` Rollback the migration process for this service, on both source and destination members.
    `void` | `shutdown(boolean terminate)` Shuts down this service.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### SERVICE_NAME

          public static final String SERVICE_NAME

      See Also:
        Constant Field Values

  - ### Constructor Detail

    - #### SemaphoreService

          public SemaphoreService(NodeEngine nodeEngine)

  - ### Method Detail

    - #### getSemaphoreContainer

          public SemaphoreContainer getSemaphoreContainer(String name)

    - #### containsSemaphore

          public boolean containsSemaphore(String name)

    - #### init

          public void init(NodeEngine nodeEngine,
                           Properties properties)

      Description copied from interface: `ManagedService`
      Initializes this service.
      Specified by:
        `init` in interface `ManagedService`
      Parameters:
        `nodeEngine` - the NodeEngine that this service belongs to
        `properties` - the Properties (can be used to pass settings to the service)

    - #### reset

          public void reset()

      Description copied from interface: `ManagedService`
      Resets this service back to its initial state.

      TODO: what is the purpose of reset

      Specified by:
        `reset` in interface `ManagedService`

    - #### shutdown

          public void shutdown(boolean terminate)

      Description copied from interface: `ManagedService`
      Shuts down this service.

      TODO: what is the purpose of the terminate variable

      Specified by:
        `shutdown` in interface `ManagedService`
      Parameters:
        `terminate` - `true` to shut down this service

    - #### memberAdded

          public void memberAdded(MembershipServiceEvent event)

      Description copied from interface: `MembershipAwareService`
      Invoked when a new member is added to the cluster. Should be non-blocking.
      Specified by:
        `memberAdded` in interface `MembershipAwareService`
      Parameters:
        `event` - the event for a new member added to the cluster

    - #### memberRemoved

          public void memberRemoved(MembershipServiceEvent event)

      Description copied from interface: `MembershipAwareService`
      Invoked when an existing member leaves the cluster. Should be non-blocking.
      Specified by:
        `memberRemoved` in interface `MembershipAwareService`
      Parameters:
        `event` - the event for an existing member leaving the cluster

    - #### memberAttributeChanged

          public void memberAttributeChanged(MemberAttributeServiceEvent event)

      Description copied from interface: `MembershipAwareService`
      Invoked when a member attribute is changed.
      Specified by:
        `memberAttributeChanged` in interface `MembershipAwareService`
      Parameters:
        `event` - the event for a member attribute being changed

    - #### createDistributedObject

          public SemaphoreProxy createDistributedObject(String objectId)

      Description copied from interface: `RemoteService`
      Creates a distributed object.
      Specified by:
        `createDistributedObject` in interface `RemoteService`
      Parameters:
        `objectId` - the name for the created distributed object
      Returns:
        the created distributed object

    - #### destroyDistributedObject

          public void destroyDistributedObject(String objectId)

      Description copied from interface: `RemoteService`
      Destroys a distributed object.
      Specified by:
        `destroyDistributedObject` in interface `RemoteService`
      Parameters:
        `objectId` - the name of the distributed object to destroy

    - #### beforeMigration

          public void beforeMigration(PartitionMigrationEvent partitionMigrationEvent)

      Description copied from interface: `MigrationAwareService`
      Called before migration process starts, on both source and destination members.

      Service can take actions required before migration. Migration process will block until this method returns. If this method fails by throwing an exception, migration process for specific partition will fail and will be rolled back.

      Specified by:
        `beforeMigration` in interface `MigrationAwareService`
      Parameters:
        `partitionMigrationEvent` - migration event

    - #### prepareReplicationOperation

          public Operation prepareReplicationOperation(PartitionReplicationEvent event)

      Description copied from interface: `MigrationAwareService`
      Returns an operation to replicate service data and/or state for a specific partition replica on another cluster member.

      This method will be called on source member whenever partitioning system requires to copy/replicate a partition replica. Returned operation will be executed on destination member. If operation fails by throwing exception, migration process will fail and will be rolled back.

      Returning null is allowed and means service does not have anything to replicate.

      Specified by:
        `prepareReplicationOperation` in interface `MigrationAwareService`
      Parameters:
        `event` - replication
      Returns:
        replication operation or null if nothing will be replicated

    - #### insertMigrationData

          public void insertMigrationData(Map<String,SemaphoreContainer> migrationData)

    - #### commitMigration

          public void commitMigration(PartitionMigrationEvent event)

      Description copied from interface: `MigrationAwareService`
      Commits the migration process for this service, on both source and destination members. This method will be called after all replication operations are executed successfully on destination and master member receives success response from all participants.

      Commit is not expected to fail at this point, all exceptions will be suppressed and logged. Implementations of this method must be thread safe as this method may be called concurrently for different migrations on different partitions.

      Specified by:
        `commitMigration` in interface `MigrationAwareService`
      Parameters:
        `event` - migration event

    - #### rollbackMigration

          public void rollbackMigration(PartitionMigrationEvent event)

      Description copied from interface: `MigrationAwareService`
      Rollback the migration process for this service, on both source and destination members. This method will be called when migration process fails at any moment. Reasons for failure may be an exception thrown on any migration step or failure(s) of any of the migration participants; either master or source or destination.

      Rollback is not expected to fail at this point, all exceptions will be suppressed and logged. Implementations of this method must be thread safe as this method may be called concurrently for different migrations on different partitions.

      Specified by:
        `rollbackMigration` in interface `MigrationAwareService`
      Parameters:
        `event` - migration event

    - #### clientDisconnected

          public void clientDisconnected(String clientUuid)

      Description copied from interface: `ClientAwareService`
      Invoked when a client disconnects from a member.
      Specified by:
        `clientDisconnected` in interface `ClientAwareService`
      Parameters:
        `clientUuid` - the UUID of the client that disconnected from a member

    - #### getQuorumName

          public String getQuorumName(String name)

      Description copied from interface: `QuorumAwareService`
      Gets the name of the quorum associated with specified operation name.
      Specified by:
        `getQuorumName` in interface `QuorumAwareService`
      Parameters:
        `name` - the operation name for which the quorum name is retured
      Returns:
        name of the associated quorum, null if there is no associated quorum

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