* Creating a transaction on the consumer side will create one instance of a transaction proxy. If during
* the transaction reads and writes are done on data that belongs to different shards then a separate transaction will
* be created on each of those shards by the TransactionProxy
- *
+ *
+ *
* The TransactionProxy does not make any guarantees about atomicity or order in which the transactions on the various
* shards will be executed.
- *
+ *
*/
public class TransactionProxy implements DOMStoreReadWriteTransaction {
+ public enum TransactionType {
+ READ_ONLY,
+ WRITE_ONLY,
+ READ_WRITE
+ }
+
+ static Function1 SAME_FAILURE_TRANSFORMER = new AbstractFunction1<
+ Throwable, Throwable>() {
+ @Override
+ public Throwable apply(Throwable failure) {
+ return failure;
+ }
+ };
+
+ private static final AtomicLong counter = new AtomicLong();
+
+ private static final Logger
+ LOG = LoggerFactory.getLogger(TransactionProxy.class);
+
+
+ /**
+ * 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 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 {
+
+ private final List 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.identifier;
+ }
+
+ @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.sendRemoteOperationAsync(actor,
+ new CloseTransaction().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 remoteTransactionActors;
+ private AtomicBoolean remoteTransactionActorsMB;
+
+ private final Map remoteTransactionPaths = new HashMap<>();
+
+ private final TransactionType transactionType;
+ private final ActorContext actorContext;
+ private final TransactionIdentifier identifier;
+ private final SchemaContext schemaContext;
+ private boolean inReadyState;
+
+ public TransactionProxy(ActorContext actorContext, TransactionType transactionType) {
+ 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");
+
+ String memberName = actorContext.getCurrentMemberName();
+ if(memberName == null){
+ memberName = "UNKNOWN-MEMBER";
+ }
+
+ this.identifier = TransactionIdentifier.builder().memberName(memberName).counter(
+ counter.getAndIncrement()).build();
+
+ if(transactionType == TransactionType.READ_ONLY) {
+ // Read-only Tx's aren't explicitly closed by the client so we create a PhantomReference
+ // to close the remote Tx's when this instance is no longer in use and is garbage
+ // collected.
+
+ remoteTransactionActors = Lists.newArrayList();
+ remoteTransactionActorsMB = new AtomicBoolean();
+
+ TransactionProxyCleanupPhantomReference cleanup =
+ new TransactionProxyCleanupPhantomReference(this);
+ phantomReferenceCache.put(cleanup, cleanup);
+ }
+
+ LOG.debug("Created txn {} of type {}", identifier, transactionType);
+ }
+
+ @VisibleForTesting
+ List> getRecordedOperationFutures() {
+ List> recordedOperationFutures = Lists.newArrayList();
+ for(TransactionContext transactionContext : remoteTransactionPaths.values()) {
+ recordedOperationFutures.addAll(transactionContext.getRecordedOperationFutures());
+ }
+
+ return recordedOperationFutures;
+ }
+
+ @Override
+ public CheckedFuture>, ReadFailedException> read(
+ final YangInstanceIdentifier path) {
+
+ Preconditions.checkState(transactionType != TransactionType.WRITE_ONLY,
+ "Read operation on write-only transaction is not allowed");
+
+ LOG.debug("Tx {} read {}", identifier, path);
+
+ createTransactionIfMissing(actorContext, path);
+
+ return transactionContext(path).readData(path);
+ }
+
@Override
- public ListenableFuture>> read(InstanceIdentifier path) {
- throw new UnsupportedOperationException("read");
+ public CheckedFuture exists(YangInstanceIdentifier path) {
+
+ Preconditions.checkState(transactionType != TransactionType.WRITE_ONLY,
+ "Exists operation on write-only transaction is not allowed");
+
+ LOG.debug("Tx {} exists {}", identifier, path);
+
+ createTransactionIfMissing(actorContext, path);
+
+ return transactionContext(path).dataExists(path);
+ }
+
+ private void checkModificationState() {
+ Preconditions.checkState(transactionType != TransactionType.READ_ONLY,
+ "Modification operation on read-only transaction is not allowed");
+ Preconditions.checkState(!inReadyState,
+ "Transaction is sealed - further modifications are not allowed");
}
@Override
- public void write(InstanceIdentifier path, NormalizedNode, ?> data) {
- throw new UnsupportedOperationException("write");
+ public void write(YangInstanceIdentifier path, NormalizedNode, ?> data) {
+
+ checkModificationState();
+
+ LOG.debug("Tx {} write {}", identifier, path);
+
+ createTransactionIfMissing(actorContext, path);
+
+ transactionContext(path).writeData(path, data);
}
@Override
- public void merge(InstanceIdentifier path, NormalizedNode, ?> data) {
- throw new UnsupportedOperationException("merge");
+ public void merge(YangInstanceIdentifier path, NormalizedNode, ?> data) {
+
+ checkModificationState();
+
+ LOG.debug("Tx {} merge {}", identifier, path);
+
+ createTransactionIfMissing(actorContext, path);
+
+ transactionContext(path).mergeData(path, data);
}
@Override
- public void delete(InstanceIdentifier path) {
- throw new UnsupportedOperationException("delete");
+ public void delete(YangInstanceIdentifier path) {
+
+ checkModificationState();
+
+ LOG.debug("Tx {} delete {}", identifier, path);
+
+ createTransactionIfMissing(actorContext, path);
+
+ transactionContext(path).deleteData(path);
}
@Override
public DOMStoreThreePhaseCommitCohort ready() {
- throw new UnsupportedOperationException("ready");
+
+ checkModificationState();
+
+ inReadyState = true;
+
+ LOG.debug("Tx {} Trying to get {} transactions ready for commit", identifier,
+ remoteTransactionPaths.size());
+
+ List> cohortPathFutures = Lists.newArrayList();
+
+ for(TransactionContext transactionContext : remoteTransactionPaths.values()) {
+
+ LOG.debug("Tx {} Readying transaction for shard {}", identifier,
+ transactionContext.getShardName());
+
+ cohortPathFutures.add(transactionContext.readyTransaction());
+ }
+
+ return new ThreePhaseCommitCohortProxy(actorContext, cohortPathFutures,
+ identifier.toString());
}
@Override
public Object getIdentifier() {
- throw new UnsupportedOperationException("getIdentifier");
+ return this.identifier;
}
@Override
public void close() {
- throw new UnsupportedOperationException("close");
+ for(TransactionContext transactionContext : remoteTransactionPaths.values()) {
+ transactionContext.closeTransaction();
+ }
+
+ remoteTransactionPaths.clear();
+
+ if(transactionType == TransactionType.READ_ONLY) {
+ remoteTransactionActors.clear();
+ remoteTransactionActorsMB.set(true);
+ }
+ }
+
+ private TransactionContext transactionContext(YangInstanceIdentifier path){
+ String shardName = shardNameFromIdentifier(path);
+ return remoteTransactionPaths.get(shardName);
+ }
+
+ private String shardNameFromIdentifier(YangInstanceIdentifier path){
+ return ShardStrategyFactory.getStrategy(path).findShard(path);
+ }
+
+ private void createTransactionIfMissing(ActorContext actorContext, YangInstanceIdentifier path) {
+ String shardName = ShardStrategyFactory.getStrategy(path).findShard(path);
+
+ TransactionContext transactionContext =
+ remoteTransactionPaths.get(shardName);
+
+ if(transactionContext != null){
+ // A transaction already exists with that shard
+ return;
+ }
+
+ try {
+ Object response = actorContext.executeShardOperation(shardName,
+ new CreateTransaction(identifier.toString(),this.transactionType.ordinal() ).toSerializable(),
+ ActorContext.ASK_DURATION);
+ if (response.getClass().equals(CreateTransactionReply.SERIALIZABLE_CLASS)) {
+ CreateTransactionReply reply =
+ CreateTransactionReply.fromSerializable(response);
+
+ String transactionPath = reply.getTransactionPath();
+
+ LOG.debug("Tx {} Received transaction 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);
+ }
+
+ transactionContext = new TransactionContextImpl(shardName, transactionPath,
+ transactionActor, identifier, actorContext, schemaContext);
+
+ remoteTransactionPaths.put(shardName, transactionContext);
+ } else {
+ throw new IllegalArgumentException(String.format(
+ "Invalid reply type {} for CreateTransaction", response.getClass()));
+ }
+ } catch(Exception e){
+ LOG.debug("Tx {} Creating NoOpTransaction because of : {}", identifier, e.getMessage());
+ remoteTransactionPaths.put(shardName, new NoOpTransactionContext(shardName, e, identifier));
+ }
+ }
+
+ private interface TransactionContext {
+ String getShardName();
+
+ void closeTransaction();
+
+ Future readyTransaction();
+
+ void writeData(YangInstanceIdentifier path, NormalizedNode, ?> data);
+
+ void deleteData(YangInstanceIdentifier path);
+
+ void mergeData(YangInstanceIdentifier path, NormalizedNode, ?> data);
+
+ CheckedFuture>, ReadFailedException> readData(
+ final YangInstanceIdentifier path);
+
+ CheckedFuture dataExists(YangInstanceIdentifier path);
+
+ List> getRecordedOperationFutures();
+ }
+
+ private static abstract class AbstractTransactionContext implements TransactionContext {
+
+ protected final TransactionIdentifier identifier;
+ protected final String shardName;
+ protected final List> recordedOperationFutures = Lists.newArrayList();
+
+ AbstractTransactionContext(String shardName, TransactionIdentifier identifier) {
+ this.shardName = shardName;
+ this.identifier = identifier;
+ }
+
+ @Override
+ public String getShardName() {
+ return shardName;
+ }
+
+ @Override
+ public List> getRecordedOperationFutures() {
+ return recordedOperationFutures;
+ }
+ }
+
+ private static class TransactionContextImpl extends AbstractTransactionContext {
+ private final Logger LOG = LoggerFactory.getLogger(TransactionContextImpl.class);
+
+ private final ActorContext actorContext;
+ private final SchemaContext schemaContext;
+ private final String actorPath;
+ private final ActorSelection actor;
+
+ private TransactionContextImpl(String shardName, String actorPath,
+ ActorSelection actor, TransactionIdentifier identifier, ActorContext actorContext,
+ SchemaContext schemaContext) {
+ super(shardName, identifier);
+ this.actorPath = actorPath;
+ this.actor = actor;
+ this.actorContext = actorContext;
+ this.schemaContext = schemaContext;
+ }
+
+ private ActorSelection getActor() {
+ return actor;
+ }
+
+ private String getResolvedCohortPath(String cohortPath) {
+ return actorContext.resolvePath(actorPath, cohortPath);
+ }
+
+ @Override
+ public void closeTransaction() {
+ LOG.debug("Tx {} closeTransaction called", identifier);
+ actorContext.sendRemoteOperationAsync(getActor(), new CloseTransaction().toSerializable());
+ }
+
+ @Override
+ public Future readyTransaction() {
+ LOG.debug("Tx {} readyTransaction called with {} previous recorded operations pending",
+ identifier, recordedOperationFutures.size());
+
+ // Send the ReadyTransaction message to the Tx actor.
+
+ final Future