package org.opendaylight.mdsal.dom.spi;
import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.base.Verify.verify;
import static java.util.Objects.requireNonNull;
-import com.google.common.base.VerifyException;
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 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);
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;
@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);
}
}
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) {
- if (!INFLIGHT_UPDATER.compareAndSet(this, tx, null)) {
- throw new IllegalStateException(String.format("Completed transaction %s while %s was submitted", tx,
- inflightTx));
- }
+ final Object witness = INFLIGHT_TX.compareAndExchange(this, tx, null);
+ checkState(witness == tx, "Completed transaction %s while %s was submitted", tx, witness);
- final PingPongTransaction nextTx = READY_UPDATER.getAndSet(this, null);
+ final PingPongTransaction nextTx = acquireReadyTx();
if (nextTx == null) {
final PingPongTransaction local = shutdownTx;
if (local != null) {
void readyTransaction(final @NonNull PingPongTransaction tx) {
// First mark the transaction as not locked.
- if (!LOCKED_UPDATER.compareAndSet(this, tx, null)) {
- throw new IllegalStateException(String.format("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.
*/
- if (!READY_UPDATER.compareAndSet(this, null, tx)) {
- throw new IllegalStateException(String.format("Transaction %s collided on ready state with %s", 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.
- if (!LOCKED_UPDATER.compareAndSet(this, tx, null)) {
- throw new VerifyException(String.format("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
Code Review / mdsal.git / commitdiff