*/
package org.opendaylight.controller.cluster.databroker.actors.dds;
+import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.base.Verify.verify;
+import static com.google.common.base.Verify.verifyNotNull;
+import static java.util.Objects.requireNonNull;
+
import akka.actor.ActorRef;
import com.google.common.base.MoreObjects;
-import com.google.common.base.Optional;
-import com.google.common.base.Preconditions;
-import com.google.common.base.Throwables;
-import com.google.common.base.Verify;
import com.google.common.collect.Iterables;
-import com.google.common.util.concurrent.CheckedFuture;
+import com.google.common.util.concurrent.FluentFuture;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Iterator;
+import java.util.Optional;
+import java.util.OptionalLong;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.function.Consumer;
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.NotThreadSafe;
+import org.checkerframework.checker.lock.qual.GuardedBy;
+import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
import org.opendaylight.controller.cluster.access.client.ConnectionEntry;
import org.opendaylight.controller.cluster.access.commands.AbstractLocalTransactionRequest;
+import org.opendaylight.controller.cluster.access.commands.ClosedTransactionException;
import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceRequest;
+import org.opendaylight.controller.cluster.access.commands.ModifyTransactionRequest;
import org.opendaylight.controller.cluster.access.commands.TransactionAbortRequest;
import org.opendaylight.controller.cluster.access.commands.TransactionAbortSuccess;
import org.opendaylight.controller.cluster.access.commands.TransactionCanCommitSuccess;
import org.opendaylight.controller.cluster.access.concepts.RequestFailure;
import org.opendaylight.controller.cluster.access.concepts.Response;
import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
-import org.opendaylight.mdsal.common.api.ReadFailedException;
import org.opendaylight.yangtools.concepts.Identifiable;
+import org.opendaylight.yangtools.yang.common.Empty;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.slf4j.Logger;
* <p>
* This class interacts with the queueing mechanism in ClientActorBehavior, hence once we arrive at a decision
* to use either a local or remote implementation, we are stuck with it. We can re-evaluate on the next transaction.
- *
- * @author Robert Varga
*/
-abstract class AbstractProxyTransaction implements Identifiable<TransactionIdentifier> {
+abstract sealed class AbstractProxyTransaction implements Identifiable<TransactionIdentifier>
+ permits LocalProxyTransaction, RemoteProxyTransaction {
/**
* Marker object used instead of read-type of requests, which are satisfied only once. This has a lower footprint
- * and allows compressing multiple requests into a single entry.
+ * and allows compressing multiple requests into a single entry. This class is not thread-safe.
*/
- @NotThreadSafe
private static final class IncrementSequence {
private final long sequence;
private long delta = 0;
}
}
- // Generic state base class. Direct instances are used for fast paths, sub-class is used for successor transitions
+ /**
+ * Base class for representing logical state of this proxy. See individual instantiations and {@link SuccessorState}
+ * for details.
+ */
private static class State {
private final String string;
State(final String string) {
- this.string = Preconditions.checkNotNull(string);
+ this.string = requireNonNull(string);
}
@Override
}
}
- // State class used when a successor has interfered. Contains coordinator latch, the successor and previous state
- private static final class SuccessorState extends State {
+ /**
+ * State class used when a successor has interfered. Contains coordinator latch, the successor and previous state.
+ * This is a temporary state introduced during reconnection process and is necessary for correct state hand-off
+ * between the old connection (potentially being accessed by the user) and the new connection (being cleaned up
+ * by the actor.
+ *
+ * <p>
+ * When a user operation encounters this state, it synchronizes on the it and wait until reconnection completes,
+ * at which point the request is routed to the successor transaction. This is a relatively heavy-weight solution
+ * to the problem of state transfer, but the user will observe it only if the race condition is hit.
+ */
+ private static class SuccessorState extends State {
private final CountDownLatch latch = new CountDownLatch(1);
private AbstractProxyTransaction successor;
private State prevState;
+ // SUCCESSOR + DONE
+ private boolean done;
+
SuccessorState() {
- super("successor");
+ super("SUCCESSOR");
}
// Synchronize with succession process and return the successor
latch.await();
} catch (InterruptedException e) {
LOG.warn("Interrupted while waiting for latch of {}", successor);
- throw Throwables.propagate(e);
+ throw new IllegalStateException(e);
}
return successor;
}
}
State getPrevState() {
- return prevState;
+ return verifyNotNull(prevState, "Attempted to access previous state, which was not set");
}
void setPrevState(final State prevState) {
- Verify.verify(this.prevState == null);
- this.prevState = Preconditions.checkNotNull(prevState);
+ verify(this.prevState == null, "Attempted to set previous state to %s when we already have %s", prevState,
+ this.prevState);
+ this.prevState = requireNonNull(prevState);
+ // We cannot have duplicate successor states, so this check is sufficient
+ done = DONE.equals(prevState);
}
// To be called from safe contexts, where successor is known to be completed
AbstractProxyTransaction getSuccessor() {
- return Verify.verifyNotNull(successor);
+ return verifyNotNull(successor);
}
void setSuccessor(final AbstractProxyTransaction successor) {
- Verify.verify(this.successor == null);
- this.successor = Preconditions.checkNotNull(successor);
+ verify(this.successor == null, "Attempted to set successor to %s when we already have %s", successor,
+ this.successor);
+ this.successor = requireNonNull(successor);
+ }
+
+ boolean isDone() {
+ return done;
+ }
+
+ void setDone() {
+ done = true;
}
}
AtomicIntegerFieldUpdater.newUpdater(AbstractProxyTransaction.class, "sealed");
private static final AtomicReferenceFieldUpdater<AbstractProxyTransaction, State> STATE_UPDATER =
AtomicReferenceFieldUpdater.newUpdater(AbstractProxyTransaction.class, State.class, "state");
- private static final State OPEN = new State("open");
- private static final State SEALED = new State("sealed");
- private static final State FLUSHED = new State("flushed");
+
+ /**
+ * Transaction has been open and is being actively worked on.
+ */
+ private static final State OPEN = new State("OPEN");
+
+ /**
+ * Transaction has been sealed by the user, but it has not completed flushing to the backed, yet. This is
+ * a transition state, as we are waiting for the user to initiate commit procedures.
+ *
+ * <p>
+ * Since the reconnect mechanics relies on state replay for transactions, this state needs to be flushed into the
+ * queue to re-create state in successor transaction (which may be based on different messages as locality may have
+ * changed). Hence the transition to {@link #FLUSHED} state needs to be handled in a thread-safe manner.
+ */
+ private static final State SEALED = new State("SEALED");
+
+ /**
+ * Transaction state has been flushed into the queue, i.e. it is visible by the successor and potentially
+ * the backend. At this point the transaction does not hold any state besides successful requests, all other state
+ * is held either in the connection's queue or the successor object.
+ *
+ * <p>
+ * Transition to this state indicates we have all input from the user we need to initiate the correct commit
+ * protocol.
+ */
+ private static final State FLUSHED = new State("FLUSHED");
+
+ /**
+ * Transaction state has been completely resolved, we have received confirmation of the transaction fate from
+ * the backend. The only remaining task left to do is finishing up the state cleanup, which is done via purge
+ * request. We need to hang on to the transaction until that is done, as we have to make sure backend completes
+ * purging its state -- otherwise we could have a leak on the backend.
+ */
+ private static final State DONE = new State("DONE");
// Touched from client actor thread only
private final Deque<Object> successfulRequests = new ArrayDeque<>();
* variable. It uses pre-allocated objects for fast paths (i.e. no successor present) and a per-transition object
* for slow paths (when successor is injected/present).
*/
- private volatile int sealed = 0;
- private volatile State state = OPEN;
-
- AbstractProxyTransaction(final ProxyHistory parent) {
- this.parent = Preconditions.checkNotNull(parent);
+ private volatile int sealed;
+ private volatile State state;
+
+ AbstractProxyTransaction(final ProxyHistory parent, final boolean isDone) {
+ this.parent = requireNonNull(parent);
+ if (isDone) {
+ state = DONE;
+ // DONE implies previous seal operation completed
+ sealed = 1;
+ } else {
+ state = OPEN;
+ }
}
final void executeInActor(final Runnable command) {
doDelete(path);
}
- final void merge(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
+ final void merge(final YangInstanceIdentifier path, final NormalizedNode data) {
checkReadWrite();
checkNotSealed();
doMerge(path, data);
}
- final void write(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
+ final void write(final YangInstanceIdentifier path, final NormalizedNode data) {
checkReadWrite();
checkNotSealed();
doWrite(path, data);
}
- final CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
+ final FluentFuture<Boolean> exists(final YangInstanceIdentifier path) {
checkNotSealed();
return doExists(path);
}
- final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
+ final FluentFuture<Optional<NormalizedNode>> read(final YangInstanceIdentifier path) {
checkNotSealed();
return doRead(path);
}
}
/**
- * Seal this transaction before it is either committed or aborted.
+ * Seal this transaction before it is either committed or aborted. This method should only be invoked from
+ * application thread.
*/
final void seal() {
// Transition user-visible state first
- final boolean success = SEALED_UPDATER.compareAndSet(this, 0, 1);
- Preconditions.checkState(success, "Proxy %s was already sealed", getIdentifier());
- internalSeal();
+ final boolean success = markSealed();
+ checkState(success, "Proxy %s was already sealed", getIdentifier());
+
+ if (!sealAndSend(OptionalLong.empty())) {
+ sealSuccessor();
+ }
}
- final void ensureSealed() {
- if (SEALED_UPDATER.compareAndSet(this, 0, 1)) {
- internalSeal();
+ /**
+ * Internal seal propagation method, invoked when we have raced with reconnection thread. Note that there may have
+ * been multiple reconnects, so we have to make sure the action is propagate through all intermediate instances.
+ */
+ private void sealSuccessor() {
+ // Slow path: wait for the successor to complete
+ final AbstractProxyTransaction successor = awaitSuccessor();
+
+ // At this point the successor has completed transition and is possibly visible by the user thread, which is
+ // still stuck here. The successor has not seen final part of our state, nor the fact it is sealed.
+ // Propagate state and seal the successor.
+ final Optional<ModifyTransactionRequest> optState = flushState();
+ if (optState.isPresent()) {
+ forwardToSuccessor(successor, optState.orElseThrow(), null);
}
+ successor.predecessorSealed();
}
- private void internalSeal() {
- doSeal();
- parent.onTransactionSealed(this);
+ private void predecessorSealed() {
+ if (markSealed() && !sealAndSend(OptionalLong.empty())) {
+ sealSuccessor();
+ }
+ }
- // Now deal with state transfer, which can occur via successor or a follow-up canCommit() or directCommit().
- if (!STATE_UPDATER.compareAndSet(this, OPEN, SEALED)) {
- // Slow path: wait for the successor to complete
- final AbstractProxyTransaction successor = awaitSuccessor();
+ /**
+ * Seal this transaction. If this method reports false, the caller needs to deal with propagating the seal operation
+ * towards the successor.
+ *
+ * @return True if seal operation was successful, false if this proxy has a successor.
+ */
+ boolean sealOnly() {
+ return sealState();
+ }
- // At this point the successor has completed transition and is possibly visible by the user thread, which is
- // still stuck here. The successor has not seen final part of our state, nor the fact it is sealed.
- // Propagate state and seal the successor.
- flushState(successor);
- successor.ensureSealed();
- }
+ /**
+ * Seal this transaction and potentially send it out towards the backend. If this method reports false, the caller
+ * needs to deal with propagating the seal operation towards the successor.
+ *
+ * @param enqueuedTicks Enqueue ticks when this is invoked from replay path.
+ * @return True if seal operation was successful, false if this proxy has a successor.
+ */
+ boolean sealAndSend(final OptionalLong enqueuedTicks) {
+ return sealState();
+ }
+
+ private boolean sealState() {
+ parent.onTransactionSealed(this);
+ // Transition internal state to sealed and detect presence of a successor
+ return STATE_UPDATER.compareAndSet(this, OPEN, SEALED);
+ }
+
+ /**
+ * Mark this proxy as having been sealed.
+ *
+ * @return True if this call has transitioned to sealed state.
+ */
+ final boolean markSealed() {
+ return SEALED_UPDATER.compareAndSet(this, 0, 1);
}
private void checkNotSealed() {
- Preconditions.checkState(sealed == 0, "Transaction %s has already been sealed", getIdentifier());
+ checkState(sealed == 0, "Transaction %s has already been sealed", getIdentifier());
}
private void checkSealed() {
- Preconditions.checkState(sealed != 0, "Transaction %s has not been sealed yet", getIdentifier());
+ checkState(sealed != 0, "Transaction %s has not been sealed yet", getIdentifier());
}
private SuccessorState getSuccessorState() {
final State local = state;
- Verify.verify(local instanceof SuccessorState, "State %s has unexpected class", local);
+ verify(local instanceof SuccessorState, "State %s has unexpected class", local);
return (SuccessorState) local;
}
}
}
- final void recordSuccessfulRequest(final @Nonnull TransactionRequest<?> req) {
- successfulRequests.add(Verify.verifyNotNull(req));
+ final void recordSuccessfulRequest(final @NonNull TransactionRequest<?> req) {
+ successfulRequests.add(verifyNotNull(req));
}
final void recordFinishedRequest(final Response<?, ?> response) {
});
}
- final void abort(final VotingFuture<Void> ret) {
+ final void abort(final VotingFuture<Empty> ret) {
checkSealed();
sendDoAbort(t -> {
} else if (t instanceof RequestFailure) {
ret.voteNo(((RequestFailure<?, ?>) t).getCause().unwrap());
} else {
- ret.voteNo(new IllegalStateException("Unhandled response " + t.getClass()));
+ ret.voteNo(unhandledResponseException(t));
}
// This is a terminal request, hence we do not need to record it
synchronized (this) {
if (STATE_UPDATER.compareAndSet(this, SEALED, FLUSHED)) {
final SettableFuture<Boolean> ret = SettableFuture.create();
- sendRequest(Verify.verifyNotNull(commitRequest(false)), t -> {
+ sendRequest(verifyNotNull(commitRequest(false)), t -> {
if (t instanceof TransactionCommitSuccess) {
ret.set(Boolean.TRUE);
} else if (t instanceof RequestFailure) {
- ret.setException(((RequestFailure<?, ?>) t).getCause().unwrap());
+ final Throwable cause = ((RequestFailure<?, ?>) t).getCause().unwrap();
+ if (cause instanceof ClosedTransactionException) {
+ // This is okay, as it indicates the transaction has been completed. It can happen
+ // when we lose connectivity with the backend after it has received the request.
+ ret.set(Boolean.TRUE);
+ } else {
+ ret.setException(cause);
+ }
} else {
- ret.setException(new IllegalStateException("Unhandled response " + t.getClass()));
+ ret.setException(unhandledResponseException(t));
}
// This is a terminal request, hence we do not need to record it
// Precludes startReconnect() from interfering with the fast path
synchronized (this) {
if (STATE_UPDATER.compareAndSet(this, SEALED, FLUSHED)) {
- final TransactionRequest<?> req = Verify.verifyNotNull(commitRequest(true));
+ final TransactionRequest<?> req = verifyNotNull(commitRequest(true));
sendRequest(req, t -> {
if (t instanceof TransactionCanCommitSuccess) {
} else if (t instanceof RequestFailure) {
ret.voteNo(((RequestFailure<?, ?>) t).getCause().unwrap());
} else {
- ret.voteNo(new IllegalStateException("Unhandled response " + t.getClass()));
+ ret.voteNo(unhandledResponseException(t));
}
recordSuccessfulRequest(req);
} else if (t instanceof RequestFailure) {
ret.voteNo(((RequestFailure<?, ?>) t).getCause().unwrap());
} else {
- ret.voteNo(new IllegalStateException("Unhandled response " + t.getClass()));
+ ret.voteNo(unhandledResponseException(t));
}
onPreCommitComplete(req);
} else if (t instanceof RequestFailure) {
ret.voteNo(((RequestFailure<?, ?>) t).getCause().unwrap());
} else {
- ret.voteNo(new IllegalStateException("Unhandled response " + t.getClass()));
+ ret.voteNo(unhandledResponseException(t));
}
LOG.debug("Transaction {} doCommit completed", this);
+
+ // Needed for ProxyHistory$Local data tree rebase points.
+ parent.completeTransaction(this);
+
enqueuePurge();
});
}
}
final void enqueuePurge(final Consumer<Response<?, ?>> callback, final long enqueuedTicks) {
- enqueueRequest(purgeRequest(), resp -> {
- LOG.debug("Transaction {} purge completed", this);
- parent.completeTransaction(this);
+ LOG.debug("{}: initiating purge", this);
+
+ final State prev = state;
+ if (prev instanceof SuccessorState) {
+ ((SuccessorState) prev).setDone();
+ } else {
+ final boolean success = STATE_UPDATER.compareAndSet(this, prev, DONE);
+ if (!success) {
+ LOG.warn("{}: moved from state {} while we were purging it", this, prev);
+ }
+ }
+
+ successfulRequests.clear();
+
+ enqueueRequest(new TransactionPurgeRequest(getIdentifier(), nextSequence(), localActor()), resp -> {
+ LOG.debug("{}: purge completed", this);
+ parent.purgeTransaction(this);
+
if (callback != null) {
callback.accept(resp);
}
}, enqueuedTicks);
}
- private TransactionPurgeRequest purgeRequest() {
- successfulRequests.clear();
- return new TransactionPurgeRequest(getIdentifier(), nextSequence(), localActor());
- }
-
// Called with the connection unlocked
final synchronized void startReconnect() {
// At this point canCommit/directCommit are blocked, we assert a new successor state, retrieving the previous
final State prevState = STATE_UPDATER.getAndSet(this, nextState);
LOG.debug("Start reconnect of proxy {} previous state {}", this, prevState);
- Verify.verify(!(prevState instanceof SuccessorState), "Proxy %s duplicate reconnect attempt after %s", this,
+ verify(!(prevState instanceof SuccessorState), "Proxy %s duplicate reconnect attempt after %s", this,
prevState);
// We have asserted a slow-path state, seal(), canCommit(), directCommit() are forced to slow paths, which will
}
// Called with the connection locked
- final void replayMessages(final AbstractProxyTransaction successor,
- final Iterable<ConnectionEntry> enqueuedEntries) {
+ final void replayMessages(final ProxyHistory successorHistory, final Iterable<ConnectionEntry> enqueuedEntries) {
final SuccessorState local = getSuccessorState();
+ final State prevState = local.getPrevState();
+
+ final AbstractProxyTransaction successor = successorHistory.createTransactionProxy(getIdentifier(),
+ isSnapshotOnly(), local.isDone());
+ LOG.debug("{} created successor {}", this, successor);
local.setSuccessor(successor);
// Replay successful requests first
for (Object obj : successfulRequests) {
if (obj instanceof TransactionRequest) {
LOG.debug("Forwarding successful request {} to successor {}", obj, successor);
- successor.replayRequest((TransactionRequest<?>) obj, resp -> { }, now);
+ successor.doReplayRequest((TransactionRequest<?>) obj, resp -> { /*NOOP*/ }, now);
} else {
- Verify.verify(obj instanceof IncrementSequence);
+ verify(obj instanceof IncrementSequence);
final IncrementSequence increment = (IncrementSequence) obj;
- successor.replayRequest(new IncrementTransactionSequenceRequest(getIdentifier(),
- increment.getSequence(), localActor(), isSnapshotOnly(), increment.getDelta()), resp -> { },
- now);
+ successor.doReplayRequest(new IncrementTransactionSequenceRequest(getIdentifier(),
+ increment.getSequence(), localActor(), isSnapshotOnly(),
+ increment.getDelta()), resp -> { /*NOOP*/ }, now);
LOG.debug("Incrementing sequence {} to successor {}", obj, successor);
}
}
final Request<?, ?> req = e.getRequest();
if (getIdentifier().equals(req.getTarget())) {
- Verify.verify(req instanceof TransactionRequest, "Unhandled request %s", req);
+ verify(req instanceof TransactionRequest, "Unhandled request %s", req);
LOG.debug("Replaying queued request {} to successor {}", req, successor);
- successor.replayRequest((TransactionRequest<?>) req, e.getCallback(), e.getEnqueuedTicks());
+ successor.doReplayRequest((TransactionRequest<?>) req, e.getCallback(), e.getEnqueuedTicks());
it.remove();
}
}
* reconnecting have been forced to slow paths, which will be unlocked once we unblock the state latch
* at the end of this method.
*/
- final State prevState = local.getPrevState();
if (SEALED.equals(prevState)) {
LOG.debug("Proxy {} reconnected while being sealed, propagating state to successor {}", this, successor);
- flushState(successor);
- successor.ensureSealed();
+ final long enqueuedTicks = parent.currentTime();
+ final Optional<ModifyTransactionRequest> optState = flushState();
+ if (optState.isPresent()) {
+ successor.handleReplayedRemoteRequest(optState.orElseThrow(), null, enqueuedTicks);
+ }
+ if (successor.markSealed()) {
+ successor.sealAndSend(OptionalLong.of(enqueuedTicks));
+ }
}
}
* @param callback Callback to be invoked once the request completes
* @param enqueuedTicks ticker-based time stamp when the request was enqueued
*/
- private void replayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
+ private void doReplayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
final long enqueuedTicks) {
if (request instanceof AbstractLocalTransactionRequest) {
handleReplayedLocalRequest((AbstractLocalTransactionRequest<?>) request, callback, enqueuedTicks);
}
}
+ final void replayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
+ final long enqueuedTicks) {
+ getSuccessorState().getSuccessor().doReplayRequest(request, callback, enqueuedTicks);
+ }
+
abstract boolean isSnapshotOnly();
abstract void doDelete(YangInstanceIdentifier path);
- abstract void doMerge(YangInstanceIdentifier path, NormalizedNode<?, ?> data);
+ abstract void doMerge(YangInstanceIdentifier path, NormalizedNode data);
- abstract void doWrite(YangInstanceIdentifier path, NormalizedNode<?, ?> data);
+ abstract void doWrite(YangInstanceIdentifier path, NormalizedNode data);
- abstract CheckedFuture<Boolean, ReadFailedException> doExists(YangInstanceIdentifier path);
+ abstract FluentFuture<Boolean> doExists(YangInstanceIdentifier path);
- abstract CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> doRead(YangInstanceIdentifier path);
-
- abstract void doSeal();
+ abstract FluentFuture<Optional<NormalizedNode>> doRead(YangInstanceIdentifier path);
@GuardedBy("this")
- abstract void flushState(AbstractProxyTransaction successor);
+ abstract Optional<ModifyTransactionRequest> flushState();
abstract TransactionRequest<?> abortRequest();
abstract void handleReplayedRemoteRequest(TransactionRequest<?> request,
@Nullable Consumer<Response<?, ?>> callback, long enqueuedTicks);
+ static final @NonNull IllegalArgumentException unhandledRequest(final TransactionRequest<?> request) {
+ return new IllegalArgumentException("Unhandled request " + request);
+ }
+
+ private static @NonNull IllegalStateException unhandledResponseException(final Response<?, ?> resp) {
+ return new IllegalStateException("Unhandled response " + resp.getClass());
+ }
+
@Override
public final String toString() {
return MoreObjects.toStringHelper(this).add("identifier", getIdentifier()).add("state", state).toString();