*/
package org.opendaylight.controller.sample.toaster.provider;
-import java.util.Arrays;
-import java.util.Collections;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
import org.opendaylight.controller.config.yang.config.toaster_provider.impl.ToasterProviderRuntimeMXBean;
import org.opendaylight.controller.md.sal.binding.api.DataBroker;
import org.opendaylight.controller.md.sal.binding.api.DataChangeListener;
+import org.opendaylight.controller.md.sal.binding.api.ReadWriteTransaction;
import org.opendaylight.controller.md.sal.binding.api.WriteTransaction;
import org.opendaylight.controller.md.sal.common.api.data.AsyncDataChangeEvent;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
+import org.opendaylight.controller.md.sal.common.api.data.OptimisticLockFailedException;
+import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitFailedException;
import org.opendaylight.controller.sal.binding.api.NotificationProviderService;
-import org.opendaylight.controller.sal.common.util.RpcErrors;
-import org.opendaylight.controller.sal.common.util.Rpcs;
import org.opendaylight.yang.gen.v1.http.netconfcentral.org.ns.toaster.rev091120.DisplayString;
import org.opendaylight.yang.gen.v1.http.netconfcentral.org.ns.toaster.rev091120.MakeToastInput;
import org.opendaylight.yang.gen.v1.http.netconfcentral.org.ns.toaster.rev091120.RestockToasterInput;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.opendaylight.yangtools.yang.common.RpcError;
-import org.opendaylight.yangtools.yang.common.RpcError.ErrorSeverity;
+import org.opendaylight.yangtools.yang.common.RpcResultBuilder;
import org.opendaylight.yangtools.yang.common.RpcError.ErrorType;
import org.opendaylight.yangtools.yang.common.RpcResult;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
+import com.google.common.base.Function;
+import com.google.common.base.Optional;
+import com.google.common.util.concurrent.AsyncFunction;
+import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.SettableFuture;
public class OpendaylightToaster implements ToasterService, ToasterProviderRuntimeMXBean,
DataChangeListener, AutoCloseable {
private final ExecutorService executor;
- // As you will see we are using multiple threads here. Therefore we need to be careful about concurrency.
- // In this case we use the taskLock to provide synchronization for the current task.
- private volatile Future<RpcResult<Void>> currentTask;
- private final Object taskLock = new Object();
+ // The following holds the Future for the current make toast task.
+ // This is used to cancel the current toast.
+ private final AtomicReference<Future<?>> currentMakeToastTask = new AtomicReference<>();
private final AtomicLong amountOfBreadInStock = new AtomicLong( 100 );
public void setDataProvider(final DataBroker salDataProvider) {
this.dataProvider = salDataProvider;
- updateStatus();
+ setToasterStatusUp( null );
}
/**
executor.shutdown();
if (dataProvider != null) {
- WriteTransaction t = dataProvider.newWriteOnlyTransaction();
- t.delete(LogicalDatastoreType.OPERATIONAL,TOASTER_IID);
- t.commit().get(); // FIXME: This call should not be blocking.
+ WriteTransaction tx = dataProvider.newWriteOnlyTransaction();
+ tx.delete(LogicalDatastoreType.OPERATIONAL,TOASTER_IID);
+ Futures.addCallback( tx.submit(), new FutureCallback<Void>() {
+ @Override
+ public void onSuccess( final Void result ) {
+ LOG.debug( "Delete Toaster commit result: " + result );
+ }
+
+ @Override
+ public void onFailure( final Throwable t ) {
+ LOG.error( "Delete of Toaster failed", t );
+ }
+ } );
}
}
- private Toaster buildToaster() {
- // We don't need to synchronize on currentTask here b/c it's declared volatile and
- // we're just doing a read.
- boolean isUp = currentTask == null;
+ private Toaster buildToaster( final ToasterStatus status ) {
// note - we are simulating a device whose manufacture and model are
// fixed (embedded) into the hardware.
// This is why the manufacture and model number are hardcoded.
- ToasterBuilder tb = new ToasterBuilder();
- tb.setToasterManufacturer(TOASTER_MANUFACTURER).setToasterModelNumber(TOASTER_MODEL_NUMBER)
- .setToasterStatus(isUp ? ToasterStatus.Up : ToasterStatus.Down);
- return tb.build();
+ return new ToasterBuilder().setToasterManufacturer( TOASTER_MANUFACTURER )
+ .setToasterModelNumber( TOASTER_MODEL_NUMBER )
+ .setToasterStatus( status )
+ .build();
}
/**
}
/**
- * RestConf RPC call implemented from the ToasterService interface.
+ * RPC call implemented from the ToasterService interface that cancels the current
+ * toast, if any.
*/
@Override
public Future<RpcResult<Void>> cancelToast() {
- synchronized (taskLock) {
- if (currentTask != null) {
- currentTask.cancel(true);
- currentTask = null;
- }
+
+ Future<?> current = currentMakeToastTask.getAndSet( null );
+ if( current != null ) {
+ current.cancel( true );
}
+
// Always return success from the cancel toast call.
- return Futures.immediateFuture(Rpcs.<Void> getRpcResult(true, Collections.<RpcError> emptySet()));
+ return Futures.immediateFuture( RpcResultBuilder.<Void> success().build() );
}
/**
- * RestConf RPC call implemented from the ToasterService interface.
+ * RPC call implemented from the ToasterService interface that attempts to make toast.
*/
@Override
public Future<RpcResult<Void>> makeToast(final MakeToastInput input) {
LOG.info("makeToast: " + input);
- synchronized (taskLock) {
- if (currentTask != null) {
- // return an error since we are already toasting some toast.
- LOG.info( "Toaster is already making toast" );
+ final SettableFuture<RpcResult<Void>> futureResult = SettableFuture.create();
- RpcResult<Void> result = Rpcs.<Void> getRpcResult(false, null, Arrays.asList(
- RpcErrors.getRpcError( "", "in-use", null, ErrorSeverity.WARNING,
- "Toaster is busy", ErrorType.APPLICATION, null ) ) );
- return Futures.immediateFuture(result);
- }
- else if( outOfBread() ) {
- RpcResult<Void> result = Rpcs.<Void> getRpcResult(false, null, Arrays.asList(
- RpcErrors.getRpcError( "out-of-stock", "resource-denied", null, null,
- "Toaster is out of bread",
- ErrorType.APPLICATION, null ) ) );
- return Futures.immediateFuture(result);
- }
- else {
- // Notice that we are moving the actual call to another thread,
- // allowing this thread to return immediately.
- // The MD-SAL design encourages asynchronus programming. If the
- // caller needs to block until the call is
- // complete then they can leverage the blocking methods on the
- // Future interface.
- currentTask = executor.submit(new MakeToastTask(input));
+ checkStatusAndMakeToast( input, futureResult, 2 );
+
+ return futureResult;
+ }
+
+ private RpcError makeToasterOutOfBreadError() {
+ return RpcResultBuilder.newError( ErrorType.APPLICATION, "resource-denied",
+ "Toaster is out of bread", "out-of-stock", null, null );
+ }
+
+ private RpcError makeToasterInUseError() {
+ return RpcResultBuilder.newWarning( ErrorType.APPLICATION, "in-use",
+ "Toaster is busy", null, null, null );
+ }
+
+ private void checkStatusAndMakeToast( final MakeToastInput input,
+ final SettableFuture<RpcResult<Void>> futureResult,
+ final int tries ) {
+
+ // Read the ToasterStatus and, if currently Up, try to write the status to Down.
+ // If that succeeds, then we essentially have an exclusive lock and can proceed
+ // to make toast.
+
+ final ReadWriteTransaction tx = dataProvider.newReadWriteTransaction();
+ ListenableFuture<Optional<Toaster>> readFuture =
+ tx.read( LogicalDatastoreType.OPERATIONAL, TOASTER_IID );
+
+ final ListenableFuture<Void> commitFuture =
+ Futures.transform( readFuture, new AsyncFunction<Optional<Toaster>,Void>() {
+
+ @Override
+ public ListenableFuture<Void> apply(
+ final Optional<Toaster> toasterData ) throws Exception {
+
+ ToasterStatus toasterStatus = ToasterStatus.Up;
+ if( toasterData.isPresent() ) {
+ toasterStatus = toasterData.get().getToasterStatus();
+ }
+
+ LOG.debug( "Read toaster status: {}", toasterStatus );
+
+ if( toasterStatus == ToasterStatus.Up ) {
+
+ if( outOfBread() ) {
+ LOG.debug( "Toaster is out of bread" );
+
+ return Futures.immediateFailedCheckedFuture(
+ new TransactionCommitFailedException( "", makeToasterOutOfBreadError() ) );
+ }
+
+ LOG.debug( "Setting Toaster status to Down" );
+
+ // We're not currently making toast - try to update the status to Down
+ // to indicate we're going to make toast. This acts as a lock to prevent
+ // concurrent toasting.
+ tx.put( LogicalDatastoreType.OPERATIONAL, TOASTER_IID,
+ buildToaster( ToasterStatus.Down ) );
+ return tx.submit();
+ }
+
+ LOG.debug( "Oops - already making toast!" );
+
+ // Return an error since we are already making toast. This will get
+ // propagated to the commitFuture below which will interpret the null
+ // TransactionStatus in the RpcResult as an error condition.
+ return Futures.immediateFailedCheckedFuture(
+ new TransactionCommitFailedException( "", makeToasterInUseError() ) );
+ }
+ } );
+
+ Futures.addCallback( commitFuture, new FutureCallback<Void>() {
+ @Override
+ public void onSuccess( final Void result ) {
+ // OK to make toast
+ currentMakeToastTask.set( executor.submit( new MakeToastTask( input, futureResult ) ) );
}
- }
- updateStatus();
- return currentTask;
+ @Override
+ public void onFailure( final Throwable ex ) {
+ if( ex instanceof OptimisticLockFailedException ) {
+
+ // Another thread is likely trying to make toast simultaneously and updated the
+ // status before us. Try reading the status again - if another make toast is
+ // now in progress, we should get ToasterStatus.Down and fail.
+
+ if( ( tries - 1 ) > 0 ) {
+ LOG.debug( "Got OptimisticLockFailedException - trying again" );
+
+ checkStatusAndMakeToast( input, futureResult, tries - 1 );
+ }
+ else {
+ futureResult.set( RpcResultBuilder.<Void> failed()
+ .withError( ErrorType.APPLICATION, ex.getMessage() ).build() );
+ }
+
+ } else {
+
+ LOG.debug( "Failed to commit Toaster status", ex );
+
+ // Probably already making toast.
+ futureResult.set( RpcResultBuilder.<Void> failed()
+ .withRpcErrors( ((TransactionCommitFailedException)ex).getErrorList() )
+ .build() );
+ }
+ }
+ } );
}
/**
public Future<RpcResult<java.lang.Void>> restockToaster(final RestockToasterInput input) {
LOG.info( "restockToaster: " + input );
- synchronized( taskLock ) {
- amountOfBreadInStock.set( input.getAmountOfBreadToStock() );
+ amountOfBreadInStock.set( input.getAmountOfBreadToStock() );
- if( amountOfBreadInStock.get() > 0 ) {
- ToasterRestocked reStockedNotification =
- new ToasterRestockedBuilder().setAmountOfBread( input.getAmountOfBreadToStock() ).build();
- notificationProvider.publish( reStockedNotification );
- }
+ if( amountOfBreadInStock.get() > 0 ) {
+ ToasterRestocked reStockedNotification = new ToasterRestockedBuilder()
+ .setAmountOfBread( input.getAmountOfBreadToStock() ).build();
+ notificationProvider.publish( reStockedNotification );
}
- return Futures.immediateFuture(Rpcs.<Void> getRpcResult(true, Collections.<RpcError> emptySet()));
+ return Futures.immediateFuture( RpcResultBuilder.<Void> success().build() );
}
/**
return toastsMade.get();
}
- private void updateStatus() {
- if (dataProvider != null) {
- WriteTransaction tx = dataProvider.newWriteOnlyTransaction();
- tx.put(LogicalDatastoreType.OPERATIONAL,TOASTER_IID, buildToaster());
+ private void setToasterStatusUp( final Function<Boolean,Void> resultCallback ) {
+
+ WriteTransaction tx = dataProvider.newWriteOnlyTransaction();
+ tx.put( LogicalDatastoreType.OPERATIONAL,TOASTER_IID, buildToaster( ToasterStatus.Up ) );
- try {
- tx.commit().get();
- } catch (InterruptedException | ExecutionException e) {
- LOG.warn("Failed to update toaster status, operational otherwise", e);
+ Futures.addCallback( tx.submit(), new FutureCallback<Void>() {
+ @Override
+ public void onSuccess( final Void result ) {
+ notifyCallback( true );
}
- } else {
- LOG.trace("No data provider configured, not updating status");
- }
+
+ @Override
+ public void onFailure( final Throwable t ) {
+ // We shouldn't get an OptimisticLockFailedException (or any ex) as no
+ // other component should be updating the operational state.
+ LOG.error( "Failed to update toaster status", t );
+
+ notifyCallback( false );
+ }
+
+ void notifyCallback( final boolean result ) {
+ if( resultCallback != null ) {
+ resultCallback.apply( result );
+ }
+ }
+ } );
}
private boolean outOfBread()
return amountOfBreadInStock.get() == 0;
}
- private class MakeToastTask implements Callable<RpcResult<Void>> {
+ private class MakeToastTask implements Callable<Void> {
final MakeToastInput toastRequest;
+ final SettableFuture<RpcResult<Void>> futureResult;
- public MakeToastTask(final MakeToastInput toast) {
- toastRequest = toast;
+ public MakeToastTask( final MakeToastInput toastRequest,
+ final SettableFuture<RpcResult<Void>> futureResult ) {
+ this.toastRequest = toastRequest;
+ this.futureResult = futureResult;
}
@Override
- public RpcResult<Void> call() {
+ public Void call() {
try
{
- // make toast just sleeps for n secondn per doneness level.
+ // make toast just sleeps for n seconds per doneness level.
long darknessFactor = OpendaylightToaster.this.darknessFactor.get();
Thread.sleep(darknessFactor * toastRequest.getToasterDoneness());
notificationProvider.publish( new ToasterOutOfBreadBuilder().build() );
}
- synchronized (taskLock) {
- currentTask = null;
- }
+ // Set the Toaster status back to up - this essentially releases the toasting lock.
+ // We can't clear the current toast task nor set the Future result until the
+ // update has been committed so we pass a callback to be notified on completion.
+
+ setToasterStatusUp( new Function<Boolean,Void>() {
+ @Override
+ public Void apply( final Boolean result ) {
+
+ currentMakeToastTask.set( null );
+
+ LOG.debug("Toast done");
- updateStatus();
+ futureResult.set( RpcResultBuilder.<Void>success().build() );
- LOG.debug("Toast done");
+ return null;
+ }
+ } );
- return Rpcs.<Void> getRpcResult(true, null, Collections.<RpcError> emptySet());
+ return null;
}
}
}
Code Review / controller.git / blobdiff