- /**
- * Time interval in between transaction create retries.
- */
- private static final FiniteDuration CREATE_TX_TRY_INTERVAL =
- FiniteDuration.create(1, TimeUnit.SECONDS);
-
- /**
- * Used to enqueue the PhantomReferences for read-only TransactionProxy instances. The
- * FinalizableReferenceQueue is safe to use statically in an OSGi environment as it uses some
- * trickery to clean up its internal thread when the bundle is unloaded.
- */
- private static final FinalizableReferenceQueue phantomReferenceQueue =
- new FinalizableReferenceQueue();
-
- /**
- * This stores the TransactionProxyCleanupPhantomReference instances statically, This is
- * necessary because PhantomReferences need a hard reference so they're not garbage collected.
- * Once finalized, the TransactionProxyCleanupPhantomReference removes itself from this map
- * and thus becomes eligible for garbage collection.
- */
- private static final Map<TransactionProxyCleanupPhantomReference,
- TransactionProxyCleanupPhantomReference> phantomReferenceCache =
- new ConcurrentHashMap<>();
-
- /**
- * A PhantomReference that closes remote transactions for a TransactionProxy when it's
- * garbage collected. This is used for read-only transactions as they're not explicitly closed
- * by clients. So the only way to detect that a transaction is no longer in use and it's safe
- * to clean up is when it's garbage collected. It's inexact as to when an instance will be GC'ed
- * but TransactionProxy instances should generally be short-lived enough to avoid being moved
- * to the old generation space and thus should be cleaned up in a timely manner as the GC
- * runs on the young generation (eden, swap1...) space much more frequently.
- */
- private static class TransactionProxyCleanupPhantomReference
- extends FinalizablePhantomReference<TransactionProxy> {
-
- private final List<ActorSelection> remoteTransactionActors;
- private final AtomicBoolean remoteTransactionActorsMB;
- private final ActorContext actorContext;
- private final TransactionIdentifier identifier;
-
- protected TransactionProxyCleanupPhantomReference(TransactionProxy referent) {
- super(referent, phantomReferenceQueue);
-
- // Note we need to cache the relevant fields from the TransactionProxy as we can't
- // have a hard reference to the TransactionProxy instance itself.
-
- remoteTransactionActors = referent.remoteTransactionActors;
- remoteTransactionActorsMB = referent.remoteTransactionActorsMB;
- actorContext = referent.actorContext;
- identifier = referent.getIdentifier();
- }
-
- @Override
- public void finalizeReferent() {
- LOG.trace("Cleaning up {} Tx actors for TransactionProxy {}",
- remoteTransactionActors.size(), identifier);
-
- phantomReferenceCache.remove(this);
-
- // Access the memory barrier volatile to ensure all previous updates to the
- // remoteTransactionActors list are visible to this thread.
-
- if(remoteTransactionActorsMB.get()) {
- for(ActorSelection actor : remoteTransactionActors) {
- LOG.trace("Sending CloseTransaction to {}", actor);
- actorContext.sendOperationAsync(actor, CloseTransaction.INSTANCE.toSerializable());
- }
- }
- }
- }
-
- /**
- * Stores the remote Tx actors for each requested data store path to be used by the
- * PhantomReference to close the remote Tx's. This is only used for read-only Tx's. The
- * remoteTransactionActorsMB volatile serves as a memory barrier to publish updates to the
- * remoteTransactionActors list so they will be visible to the thread accessing the
- * PhantomReference.
- */
- private List<ActorSelection> remoteTransactionActors;
- private volatile AtomicBoolean remoteTransactionActorsMB;
-
- /**
- * Stores the create transaction results per shard.
- */
- private final Map<String, TransactionFutureCallback> txFutureCallbackMap = new HashMap<>();
-
- private final TransactionType transactionType;
- private final ActorContext actorContext;
- private final String transactionChainId;
- private final SchemaContext schemaContext;
- private boolean inReadyState;
-
- private volatile boolean initialized;
- private Semaphore operationLimiter;
- private OperationCompleter operationCompleter;
-
- public TransactionProxy(ActorContext actorContext, TransactionType transactionType) {
- this(actorContext, transactionType, "");
- }
-
- public TransactionProxy(ActorContext actorContext, TransactionType transactionType, String transactionChainId) {
- super(createIdentifier(actorContext));
- this.actorContext = Preconditions.checkNotNull(actorContext,
- "actorContext should not be null");
- this.transactionType = Preconditions.checkNotNull(transactionType,
- "transactionType should not be null");
- this.schemaContext = Preconditions.checkNotNull(actorContext.getSchemaContext(),
- "schemaContext should not be null");
- this.transactionChainId = transactionChainId;
-
- LOG.debug("Created txn {} of type {} on chain {}", getIdentifier(), transactionType, transactionChainId);
- }
-
- private static TransactionIdentifier createIdentifier(ActorContext actorContext) {
- String memberName = actorContext.getCurrentMemberName();
- if (memberName == null) {
- memberName = "UNKNOWN-MEMBER";
- }
-
- return new TransactionIdentifier(memberName, counter.getAndIncrement());
- }