Package com.sodius.oslc.server.trs.store

Class TrsStoreSynchronizer

java.lang.Object
com.sodius.oslc.server.trs.store.TrsStoreSynchronizer
public class TrsStoreSynchronizer extends Object
Provides synchronized (and non-synchronized) access to a TrsStore. This class is to guarantee store methods are never executed concurrently but one at a time across the whole web application.

It also provides a ResourceEventStore implementation whose methods are non-synchronized, so that callers (usually listeners in the application) do not need to take care on their own about this.

Since:
1.10.0

  • Constructor Details

    • TrsStoreSynchronizer

      public TrsStoreSynchronizer(TrsStore store)
      Creates a synchronizer instance wrapping the specified store. The constructor calls TrsStore.createSynchronizer() to obtain an Executor to execute operations sequentially.
      Parameters:
      store - a TRS store.

  • Method Details

    • applyLock

      public <R> R applyLock(TrsStoreFunction<R> function) throws TrsStoreException
      Executes a function using the underlying synchronizer, which guarantees only one function can be executed at a time across the whole web application. The function takes as argument the wrapped TrsStore instance.

      This method is to use when TRS data needs to be updated in the store. Prefer using applyUnlock(TrsStoreFunction) for read-only operations.

      Type Parameters:
      R - the type of the result of the function
      Parameters:
      function - the function to execute through the synchronizer
      Returns:
      the result of the specified function
      Throws:
      TrsStoreException - when the function raises such exception or the synchronizer fails to complete the execution
      Since:
      3.5.0

    • applyUnlock

      public <R> R applyUnlock(TrsStoreFunction<R> function) throws TrsStoreException
      Executes a read-only function using the underlying TrsStore instance. The function is executed right away, without any lock, and concurrently with other functions using this same method.

      This method is to use exclusively for reading TRS data from the store. Any attempt to modify the store will be rejected with an exception. Caller shall use applyLock(TrsStoreFunction) for write operations.

      Type Parameters:
      R - the type of the result of the function
      Parameters:
      function - the function to execute on the store
      Returns:
      the result of the specified function
      Throws:
      TrsStoreException - when the function raises such exception
      Since:
      3.5.0

    • getResourceEventStore

      public ResourceEventStore getResourceEventStore()
      Returns an event store designed for listeners registered in the application. Such listeners can call ResourceEventStore.store(ResourceEvent...) methods without taking care on their own of the synchronization. This store implementation records in memory the events to be stored and immediately returns, so that listeners are guaranteed not to be blocked until the events are stored. The actual storage is performed in a separate thread and synchronized with the TrsStore using the applyLock(TrsStoreFunction) method.
      Returns:
      an asynchronized event store for application listeners.

    • isResourceEventStoreIdle

      public boolean isResourceEventStoreIdle()
      Determines whether the event store has remaining event storage requests being processed asynchronously.
      Returns:
      true if no event storage request is currently being processed, false if the store is actively storing data.

    • createResourceEventExecutor

      protected ExecutorService createResourceEventExecutor()
      Creates the executor service for storing events in the store. Default implementation uses Executors.newSingleThreadExecutor() passing Threads.getThreadFactory() as argument. Applications may override this method to customize the ExecutorService.
      Returns:
      the executor service for storing events in the store.
      Since:
      3.9.0