- /**
- * Implements a Future OnComplete callback for a CreateTransaction message. This class handles
- * retries, up to a limit, if the shard doesn't have a leader yet. This is done by scheduling a
- * retry task after a short delay.
- * <p>
- * The end result from a completed CreateTransaction message is a TransactionContext that is
- * used to perform transaction operations. Transaction operations that occur before the
- * CreateTransaction completes are cache and executed once the CreateTransaction completes,
- * successfully or not.
- */
- private class TransactionFutureCallback extends OnComplete<Object> {
-
- /**
- * The list of transaction operations to execute once the CreateTransaction completes.
- */
- @GuardedBy("txOperationsOnComplete")
- private final List<TransactionOperation> txOperationsOnComplete = Lists.newArrayList();
-
- /**
- * The TransactionContext resulting from the CreateTransaction reply.
- */
- private volatile TransactionContext transactionContext;
-
- /**
- * The target primary shard.
- */
- private volatile ActorSelection primaryShard;
-
- private volatile int createTxTries = (int) (actorContext.getDatastoreContext().
- getShardLeaderElectionTimeout().duration().toMillis() /
- CREATE_TX_TRY_INTERVAL.toMillis());
-
- private final String shardName;
-
- TransactionFutureCallback(String shardName) {
- this.shardName = shardName;
- }
-
- String getShardName() {
- return shardName;
- }
-
- TransactionContext getTransactionContext() {
- return transactionContext;
- }
-
-
- /**
- * Sets the target primary shard and initiates a CreateTransaction try.
- */
- void setPrimaryShard(ActorSelection primaryShard) {
- LOG.debug("Tx {} Primary shard found - trying create transaction", identifier);
-
- this.primaryShard = primaryShard;
- tryCreateTransaction();
- }
-
- /**
- * Adds a TransactionOperation to be executed after the CreateTransaction completes.
- */
- void addTxOperationOnComplete(TransactionOperation operation) {
- synchronized(txOperationsOnComplete) {
- if(transactionContext == null) {
- LOG.debug("Tx {} Adding operation on complete {}", identifier);
-
- txOperationsOnComplete.add(operation);
- } else {
- operation.invoke(transactionContext);
- }
- }
- }
-
-
- <T> Future<T> enqueueFutureOperation(final FutureOperation<T> op) {
-
- Future<T> future;
-
- if (transactionContext != null) {
- future = op.invoke(transactionContext);
- } else {
- // The shard Tx hasn't been created yet so add the Tx operation to the Tx Future
- // callback to be executed after the Tx is created.
- final Promise<T> promise = akka.dispatch.Futures.promise();
- addTxOperationOnComplete(new TransactionOperation() {
- @Override
- public void invoke(TransactionContext transactionContext) {
- promise.completeWith(op.invoke(transactionContext));
- }
- });
-
- future = promise.future();
- }
-
- return future;
- }
-
- <T> CheckedFuture<T, ReadFailedException> enqueueReadOperation(final ReadOperation<T> op) {
-
- CheckedFuture<T, ReadFailedException> future;
-
- if (transactionContext != null) {
- future = op.invoke(transactionContext);
- } else {
- // The shard Tx hasn't been created yet so add the Tx operation to the Tx Future
- // callback to be executed after the Tx is created.
- final SettableFuture<T> proxyFuture = SettableFuture.create();
- addTxOperationOnComplete(new TransactionOperation() {
- @Override
- public void invoke(TransactionContext transactionContext) {
- Futures.addCallback(op.invoke(transactionContext), new FutureCallback<T>() {
- @Override
- public void onSuccess(T data) {
- proxyFuture.set(data);
- }
-
- @Override
- public void onFailure(Throwable t) {
- proxyFuture.setException(t);
- }
- });
- }
- });
-
- future = MappingCheckedFuture.create(proxyFuture, ReadFailedException.MAPPER);
- }
-
- return future;
- }
-
- void enqueueModifyOperation(final TransactionOperation op) {
-
- if (transactionContext != null) {
- op.invoke(transactionContext);
- } else {
- // The shard Tx hasn't been created yet so add the Tx operation to the Tx Future
- // callback to be executed after the Tx is created.
- addTxOperationOnComplete(op);
- }
- }
-
- /**
- * Performs a CreateTransaction try async.
- */
- private void tryCreateTransaction() {
- Future<Object> createTxFuture = sendCreateTransaction(primaryShard,
- new CreateTransaction(identifier.toString(),
- TransactionProxy.this.transactionType.ordinal(),
- getTransactionChainId()).toSerializable());
-
- createTxFuture.onComplete(this, actorContext.getActorSystem().dispatcher());
- }
-
- @Override
- public void onComplete(Throwable failure, Object response) {
- if(failure instanceof NoShardLeaderException) {
- // There's no leader for the shard yet - schedule and try again, unless we're out
- // of retries. Note: createTxTries is volatile as it may be written by different
- // threads however not concurrently, therefore decrementing it non-atomically here
- // is ok.
- if(--createTxTries > 0) {
- LOG.debug("Tx {} Shard {} has no leader yet - scheduling create Tx retry",
- identifier, shardName);
-
- actorContext.getActorSystem().scheduler().scheduleOnce(CREATE_TX_TRY_INTERVAL,
- new Runnable() {
- @Override
- public void run() {
- tryCreateTransaction();
- }
- }, actorContext.getActorSystem().dispatcher());
- return;
- }
- }
-
- // Create the TransactionContext from the response or failure and execute delayed
- // TransactionOperations. This entire section is done atomically (ie synchronized) with
- // respect to #addTxOperationOnComplete to handle timing issues and ensure no
- // TransactionOperation is missed and that they are processed in the order they occurred.
- synchronized(txOperationsOnComplete) {
- // Store the new TransactionContext locally until we've completed invoking the
- // TransactionOperations. This avoids thread timing issues which could cause
- // out-of-order TransactionOperations. Eg, on a modification operation, if the
- // TransactionContext is non-null, then we directly call the TransactionContext.
- // However, at the same time, the code may be executing the cached
- // TransactionOperations. So to avoid thus timing, we don't publish the
- // TransactionContext until after we've executed all cached TransactionOperations.
- TransactionContext localTransactionContext;
- if(failure != null) {
- LOG.debug("Tx {} Creating NoOpTransaction because of error: {}", identifier,
- failure.getMessage());
-
- localTransactionContext = new NoOpTransactionContext(failure, identifier, operationLimiter);
- } else if (response.getClass().equals(CreateTransactionReply.SERIALIZABLE_CLASS)) {
- localTransactionContext = createValidTransactionContext(
- CreateTransactionReply.fromSerializable(response));
- } else {
- IllegalArgumentException exception = new IllegalArgumentException(String.format(
- "Invalid reply type %s for CreateTransaction", response.getClass()));
-
- localTransactionContext = new NoOpTransactionContext(exception, identifier, operationLimiter);
- }
-
- for(TransactionOperation oper: txOperationsOnComplete) {
- oper.invoke(localTransactionContext);
- }
-
- txOperationsOnComplete.clear();
-
- // We're done invoking the TransactionOperations so we can now publish the
- // TransactionContext.
- transactionContext = localTransactionContext;
- }
- }
-
- private TransactionContext createValidTransactionContext(CreateTransactionReply reply) {
- String transactionPath = reply.getTransactionPath();
-
- LOG.debug("Tx {} Received transaction actor path {}", identifier, transactionPath);
-
- ActorSelection transactionActor = actorContext.actorSelection(transactionPath);
-
- if (transactionType == TransactionType.READ_ONLY) {
- // Add the actor to the remoteTransactionActors list for access by the
- // cleanup PhantonReference.
- remoteTransactionActors.add(transactionActor);
-
- // Write to the memory barrier volatile to publish the above update to the
- // remoteTransactionActors list for thread visibility.
- remoteTransactionActorsMB.set(true);
- }
-
- // TxActor is always created where the leader of the shard is.
- // Check if TxActor is created in the same node
- boolean isTxActorLocal = actorContext.isPathLocal(transactionPath);
-
- return new TransactionContextImpl(transactionPath, transactionActor, identifier,
- actorContext, schemaContext, isTxActorLocal, reply.getVersion(), operationCompleter);
- }