import com.google.common.util.concurrent.FluentFuture;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.MoreExecutors;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
import java.util.AbstractMap.SimpleImmutableEntry;
import java.util.Map.Entry;
import java.util.Optional;
import java.util.concurrent.CancellationException;
-import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.function.Function;
-import javax.annotation.concurrent.GuardedBy;
+import org.checkerframework.checker.lock.qual.GuardedBy;
+import org.checkerframework.checker.lock.qual.Holding;
import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
import org.opendaylight.mdsal.common.api.CommitInfo;
import org.opendaylight.mdsal.common.api.LogicalDatastoreType;
import org.opendaylight.mdsal.dom.api.DOMDataTreeReadTransaction;
@GuardedBy("this")
private Entry<PingPongTransaction, Throwable> deadTx;
- // This updater is used to manipulate the "ready" transaction. We perform only atomic get-and-set on it.
- private static final AtomicReferenceFieldUpdater<PingPongTransactionChain, PingPongTransaction> READY_UPDATER =
- AtomicReferenceFieldUpdater.newUpdater(PingPongTransactionChain.class, PingPongTransaction.class,
- "readyTx");
+ // This VarHandle is used to manipulate the "ready" transaction. We perform only atomic get-and-set on it.
+ private static final VarHandle READY_TX;
+ @SuppressWarnings("unused")
private volatile PingPongTransaction readyTx;
/*
- * This updater is used to manipulate the "locked" transaction. A locked transaction means we know that the user
+ * This VarHandle is used to manipulate the "locked" transaction. A locked transaction means we know that the user
* still holds a transaction and should at some point call us. We perform on compare-and-swap to ensure we properly
* detect when a user is attempting to allocated multiple transactions concurrently.
*/
- private static final AtomicReferenceFieldUpdater<PingPongTransactionChain, PingPongTransaction> LOCKED_UPDATER =
- AtomicReferenceFieldUpdater.newUpdater(PingPongTransactionChain.class, PingPongTransaction.class,
- "lockedTx");
+ private static final VarHandle LOCKED_TX;
private volatile PingPongTransaction lockedTx;
/*
* This updater is used to manipulate the "inflight" transaction. There can be at most one of these at any given
* time. We perform only compare-and-swap on these.
*/
- private static final AtomicReferenceFieldUpdater<PingPongTransactionChain, PingPongTransaction> INFLIGHT_UPDATER =
- AtomicReferenceFieldUpdater.newUpdater(PingPongTransactionChain.class, PingPongTransaction.class,
- "inflightTx");
+ private static final VarHandle INFLIGHT_TX;
private volatile PingPongTransaction inflightTx;
+ static {
+ final var lookup = MethodHandles.lookup();
+ try {
+ INFLIGHT_TX = lookup.findVarHandle(PingPongTransactionChain.class, "inflightTx", PingPongTransaction.class);
+ LOCKED_TX = lookup.findVarHandle(PingPongTransactionChain.class, "lockedTx", PingPongTransaction.class);
+ READY_TX = lookup.findVarHandle(PingPongTransactionChain.class, "readyTx", PingPongTransaction.class);
+ } catch (NoSuchFieldException | IllegalAccessException e) {
+ throw new ExceptionInInitializerError(e);
+ }
+ }
+
public PingPongTransactionChain(final Function<DOMTransactionChainListener, DOMTransactionChain> delegateFactory,
final DOMTransactionChainListener listener) {
this.listener = requireNonNull(listener);
- this.delegate = delegateFactory.apply(new DOMTransactionChainListener() {
+ delegate = delegateFactory.apply(new DOMTransactionChainListener() {
@Override
public void onTransactionChainFailed(final DOMTransactionChain chain,
final DOMDataTreeTransaction transaction, final Throwable cause) {
final DOMDataTreeReadWriteTransaction delegateTx = delegate.newReadWriteTransaction();
final PingPongTransaction newTx = new PingPongTransaction(delegateTx);
- if (!LOCKED_UPDATER.compareAndSet(this, null, newTx)) {
+ final Object witness = LOCKED_TX.compareAndExchange(this, null, newTx);
+ if (witness != null) {
delegateTx.cancel();
throw new IllegalStateException(
- String.format("New transaction %s raced with transaction %s", newTx, lockedTx));
+ String.format("New transaction %s raced with transaction %s", newTx, witness));
}
return newTx;
}
+ private @Nullable PingPongTransaction acquireReadyTx() {
+ return (PingPongTransaction) READY_TX.getAndSet(this, null);
+ }
+
private @NonNull PingPongTransaction allocateTransaction() {
// Step 1: acquire current state
- final PingPongTransaction oldTx = READY_UPDATER.getAndSet(this, null);
+ final PingPongTransaction oldTx = acquireReadyTx();
// Slow path: allocate a delegate transaction
if (oldTx == null) {
}
// Fast path: reuse current transaction. We will check failures and similar on commit().
- if (!LOCKED_UPDATER.compareAndSet(this, null, oldTx)) {
+ final Object witness = LOCKED_TX.compareAndExchange(this, null, oldTx);
+ if (witness != null) {
// Ouch. Delegate chain has not detected a duplicate transaction allocation. This is the best we can do.
oldTx.getTransaction().cancel();
throw new IllegalStateException(String.format("Reusable transaction %s raced with transaction %s", oldTx,
- lockedTx));
+ witness));
}
return oldTx;
* This forces allocateTransaction() on a slow path, which has to happen after this method has completed executing.
* Also inflightTx may be updated outside the lock, hence we need to re-check.
*/
- @GuardedBy("this")
+ @Holding("this")
private void processIfReady() {
if (inflightTx == null) {
- final PingPongTransaction tx = READY_UPDATER.getAndSet(this, null);
+ final PingPongTransaction tx = acquireReadyTx();
if (tx != null) {
processTransaction(tx);
}
*
* @param tx Transaction which needs processing.
*/
- @GuardedBy("this")
+ @Holding("this")
private void processTransaction(final @NonNull PingPongTransaction tx) {
if (failed) {
LOG.debug("Cancelling transaction {}", tx);
}
LOG.debug("Submitting transaction {}", tx);
- if (!INFLIGHT_UPDATER.compareAndSet(this, null, tx)) {
- LOG.warn("Submitting transaction {} while {} is still running", tx, inflightTx);
+ final Object witness = INFLIGHT_TX.compareAndExchange(this, null, tx);
+ if (witness != null) {
+ LOG.warn("Submitting transaction {} while {} is still running", tx, witness);
}
tx.getTransaction().commit().addCallback(new FutureCallback<CommitInfo>() {
* correctness.
*/
private synchronized void processNextTransaction(final PingPongTransaction tx) {
- final boolean success = INFLIGHT_UPDATER.compareAndSet(this, tx, null);
- checkState(success, "Completed transaction %s while %s was submitted", tx, inflightTx);
-
- final PingPongTransaction nextTx = READY_UPDATER.getAndSet(this, null);
- if (nextTx != null) {
+ final Object witness = INFLIGHT_TX.compareAndExchange(this, tx, null);
+ checkState(witness == tx, "Completed transaction %s while %s was submitted", tx, witness);
+
+ final PingPongTransaction nextTx = acquireReadyTx();
+ if (nextTx == null) {
+ final PingPongTransaction local = shutdownTx;
+ if (local != null) {
+ processTransaction(local);
+ delegate.close();
+ shutdownTx = null;
+ }
+ } else {
processTransaction(nextTx);
- } else if (shutdownTx != null) {
- processTransaction(shutdownTx);
- delegate.close();
- shutdownTx = null;
}
}
void readyTransaction(final @NonNull PingPongTransaction tx) {
// First mark the transaction as not locked.
- final boolean lockedMatch = LOCKED_UPDATER.compareAndSet(this, tx, null);
- checkState(lockedMatch, "Attempted to submit transaction %s while we have %s", tx, lockedTx);
+ final Object lockedWitness = LOCKED_TX.compareAndExchange(this, tx, null);
+ checkState(lockedWitness == tx, "Attempted to submit transaction %s while we have %s", tx, lockedWitness);
LOG.debug("Transaction {} unlocked", tx);
/*
* The transaction is ready. It will then be picked up by either next allocation,
* or a background transaction completion callback.
*/
- final boolean success = READY_UPDATER.compareAndSet(this, null, tx);
- checkState(success, "Transaction %s collided on ready state", tx, readyTx);
+ final Object readyWitness = READY_TX.compareAndExchange(this, null, tx);
+ checkState(readyWitness == null, "Transaction %s collided on ready state with %s", tx, readyWitness);
LOG.debug("Transaction {} readied", tx);
/*
synchronized void cancelTransaction(final PingPongTransaction tx,
final DOMDataTreeReadWriteTransaction frontendTx) {
// Attempt to unlock the operation.
- final boolean lockedMatch = LOCKED_UPDATER.compareAndSet(this, tx, null);
- verify(lockedMatch, "Cancelling transaction %s collided with locked transaction %s", tx, lockedTx);
+ final Object witness = LOCKED_TX.compareAndExchange(this, tx, null);
+ verify(witness == tx, "Cancelling transaction %s collided with locked transaction %s", tx, witness);
// Cancel the backend transaction, so we do not end up leaking it.
final boolean backendCancelled = tx.getTransaction().cancel();
}
// Force allocations on slow path, picking up a potentially-outstanding transaction
- final PingPongTransaction tx = READY_UPDATER.getAndSet(this, null);
+ final PingPongTransaction tx = acquireReadyTx();
if (tx != null) {
// We have one more transaction, which needs to be processed somewhere. If we do not
@Override
public DOMDataTreeReadTransaction newReadOnlyTransaction() {
+ return new PingPongReadTransaction(allocateTransaction());
+ }
+
+ @Override
+ public DOMDataTreeReadWriteTransaction newReadWriteTransaction() {
final PingPongTransaction tx = allocateTransaction();
+ final DOMDataTreeReadWriteTransaction ret = new PingPongReadWriteTransaction(tx);
+ tx.recordFrontendTransaction(ret);
+ return ret;
+ }
- return new DOMDataTreeReadTransaction() {
- @Override
- public FluentFuture<Optional<NormalizedNode<?, ?>>> read(
- final LogicalDatastoreType store, final YangInstanceIdentifier path) {
- return tx.getTransaction().read(store, path);
- }
+ @Override
+ public DOMDataTreeWriteTransaction newWriteOnlyTransaction() {
+ return newReadWriteTransaction();
+ }
- @Override
- public FluentFuture<Boolean> exists(final LogicalDatastoreType store, final YangInstanceIdentifier path) {
- return tx.getTransaction().exists(store, path);
- }
+ private final class PingPongReadTransaction implements DOMDataTreeReadTransaction {
+ private final @NonNull PingPongTransaction tx;
- @Override
- public Object getIdentifier() {
- return tx.getTransaction().getIdentifier();
- }
+ PingPongReadTransaction(final PingPongTransaction tx) {
+ this.tx = requireNonNull(tx);
+ }
- @Override
- public void close() {
- readyTransaction(tx);
- }
- };
+ @Override
+ public FluentFuture<Optional<NormalizedNode>> read(final LogicalDatastoreType store,
+ final YangInstanceIdentifier path) {
+ return tx.getTransaction().read(store, path);
+ }
+
+ @Override
+ public FluentFuture<Boolean> exists(final LogicalDatastoreType store, final YangInstanceIdentifier path) {
+ return tx.getTransaction().exists(store, path);
+ }
+
+ @Override
+ public Object getIdentifier() {
+ return tx.getTransaction().getIdentifier();
+ }
+
+ @Override
+ public void close() {
+ readyTransaction(tx);
+ }
}
- @Override
- public DOMDataTreeReadWriteTransaction newReadWriteTransaction() {
- final PingPongTransaction tx = allocateTransaction();
- final DOMDataTreeReadWriteTransaction ret = new ForwardingDOMDataReadWriteTransaction() {
- private boolean isOpen = true;
+ private final class PingPongReadWriteTransaction extends ForwardingDOMDataReadWriteTransaction {
+ private final @NonNull PingPongTransaction tx;
- @Override
- protected DOMDataTreeReadWriteTransaction delegate() {
- return tx.getTransaction();
- }
+ private boolean isOpen = true;
- @Override
- public FluentFuture<? extends CommitInfo> commit() {
- readyTransaction(tx);
- isOpen = false;
- return tx.getCommitFuture().transform(ignored -> CommitInfo.empty(), MoreExecutors.directExecutor());
- }
+ PingPongReadWriteTransaction(final PingPongTransaction tx) {
+ this.tx = requireNonNull(tx);
+ }
- @Override
- public boolean cancel() {
- if (isOpen) {
- cancelTransaction(tx, this);
- isOpen = false;
- return true;
- }
-
- return false;
+ @Override
+ public FluentFuture<? extends CommitInfo> commit() {
+ readyTransaction(tx);
+ isOpen = false;
+ return tx.getCommitFuture().transform(ignored -> CommitInfo.empty(), MoreExecutors.directExecutor());
+ }
+
+ @Override
+ public boolean cancel() {
+ if (isOpen) {
+ cancelTransaction(tx, this);
+ isOpen = false;
+ return true;
}
- };
- tx.recordFrontendTransaction(ret);
- return ret;
- }
+ return false;
+ }
- @Override
- public DOMDataTreeWriteTransaction newWriteOnlyTransaction() {
- return newReadWriteTransaction();
+ @Override
+ protected DOMDataTreeReadWriteTransaction delegate() {
+ return tx.getTransaction();
+ }
}
}
Code Review / mdsal.git / blobdiff