netconf/sal-netconf-connector/src/main/java/org/opendaylight/netconf/sal/connect/netconf/NetconfDevice.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.netconf.sal.connect.netconf;
   9
  10 import static com.google.common.base.Preconditions.checkState;
  11 import static java.util.Objects.requireNonNull;
  12
  13 import com.google.common.base.Predicates;
  14 import com.google.common.collect.Collections2;
  15 import com.google.common.collect.Sets;
  16 import com.google.common.util.concurrent.FutureCallback;
  17 import com.google.common.util.concurrent.Futures;
  18 import com.google.common.util.concurrent.ListenableFuture;
  19 import com.google.common.util.concurrent.ListeningExecutorService;
  20 import com.google.common.util.concurrent.MoreExecutors;
  21 import com.google.common.util.concurrent.SettableFuture;
  22 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  23 import io.netty.util.concurrent.EventExecutor;
  24 import java.util.ArrayList;
  25 import java.util.Collection;
  26 import java.util.Collections;
  27 import java.util.LinkedList;
  28 import java.util.List;
  29 import java.util.Optional;
  30 import java.util.Set;
  31 import java.util.concurrent.ExecutionException;
  32 import java.util.concurrent.TimeUnit;
  33 import java.util.stream.Collectors;
  34 import org.checkerframework.checker.lock.qual.GuardedBy;
  35 import org.opendaylight.mdsal.dom.api.DOMRpcResult;
  36 import org.opendaylight.mdsal.dom.api.DOMRpcService;
  37 import org.opendaylight.netconf.api.NetconfMessage;
  38 import org.opendaylight.netconf.sal.connect.api.DeviceActionFactory;
  39 import org.opendaylight.netconf.sal.connect.api.MessageTransformer;
  40 import org.opendaylight.netconf.sal.connect.api.NetconfDeviceSchemasResolver;
  41 import org.opendaylight.netconf.sal.connect.api.RemoteDevice;
  42 import org.opendaylight.netconf.sal.connect.api.RemoteDeviceCommunicator;
  43 import org.opendaylight.netconf.sal.connect.api.RemoteDeviceHandler;
  44 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfDeviceCapabilities;
  45 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfDeviceCommunicator;
  46 import org.opendaylight.netconf.sal.connect.netconf.listener.NetconfSessionPreferences;
  47 import org.opendaylight.netconf.sal.connect.netconf.sal.NetconfDeviceRpc;
  48 import org.opendaylight.netconf.sal.connect.netconf.schema.mapping.BaseSchema;
  49 import org.opendaylight.netconf.sal.connect.netconf.schema.mapping.NetconfMessageTransformer;
  50 import org.opendaylight.netconf.sal.connect.netconf.util.NetconfMessageTransformUtil;
  51 import org.opendaylight.netconf.sal.connect.util.RemoteDeviceId;
  52 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.notifications.rev120206.NetconfCapabilityChange;
  53 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.optional.rev190614.NetconfNodeAugmentedOptional;
  54 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.NetconfNode;
  55 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.netconf.node.connection.status.available.capabilities.AvailableCapabilityBuilder;
  56 import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.netconf.node.connection.status.unavailable.capabilities.UnavailableCapability;
  57 import org.opendaylight.yangtools.rcf8528.data.util.EmptyMountPointContext;
  58 import org.opendaylight.yangtools.rfc8528.data.api.MountPointContext;
  59 import org.opendaylight.yangtools.yang.common.QName;
  60 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  61 import org.opendaylight.yangtools.yang.model.repo.api.MissingSchemaSourceException;
  62 import org.opendaylight.yangtools.yang.model.repo.api.SchemaContextFactory;
  63 import org.opendaylight.yangtools.yang.model.repo.api.SchemaRepository;
  64 import org.opendaylight.yangtools.yang.model.repo.api.SchemaResolutionException;
  65 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
  66 import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
  67 import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource;
  68 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceProvider;
  69 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistration;
  70 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistry;
  71 import org.slf4j.Logger;
  72 import org.slf4j.LoggerFactory;
  73
  74 /**
  75  *  This is a mediator between NetconfDeviceCommunicator and NetconfDeviceSalFacade.
  76  */
  77 public class NetconfDevice
  78         implements RemoteDevice<NetconfSessionPreferences, NetconfMessage, NetconfDeviceCommunicator> {
  79
  80     @SuppressFBWarnings(value = "SLF4J_LOGGER_SHOULD_BE_PRIVATE",
  81             justification = "Needed for common logging of related classes")
  82     static final Logger LOG = LoggerFactory.getLogger(NetconfDevice.class);
  83
  84     protected final RemoteDeviceId id;
  85     protected final SchemaContextFactory schemaContextFactory;
  86     protected final SchemaSourceRegistry schemaRegistry;
  87     protected final SchemaRepository schemaRepository;
  88
  89     protected final List<SchemaSourceRegistration<?>> sourceRegistrations = new ArrayList<>();
  90
  91     private final RemoteDeviceHandler<NetconfSessionPreferences> salFacade;
  92     private final ListeningExecutorService processingExecutor;
  93     private final DeviceActionFactory deviceActionFactory;
  94     private final NetconfDeviceSchemasResolver stateSchemasResolver;
  95     private final NotificationHandler notificationHandler;
  96     private final boolean reconnectOnSchemasChange;
  97     private final NetconfNode node;
  98     private final EventExecutor eventExecutor;
  99     private final NetconfNodeAugmentedOptional nodeOptional;
 100
 101     @GuardedBy("this")
 102     private boolean connected = false;
 103
 104     // Message transformer is constructed once the schemas are available
 105     private MessageTransformer<NetconfMessage> messageTransformer;
 106
 107     public NetconfDevice(final SchemaResourcesDTO schemaResourcesDTO, final RemoteDeviceId id,
 108                          final RemoteDeviceHandler<NetconfSessionPreferences> salFacade,
 109                          final ListeningExecutorService globalProcessingExecutor,
 110                          final boolean reconnectOnSchemasChange) {
 111         this(schemaResourcesDTO, id, salFacade, globalProcessingExecutor, reconnectOnSchemasChange, null, null, null,
 112                 null);
 113     }
 114
 115     public NetconfDevice(final SchemaResourcesDTO schemaResourcesDTO, final RemoteDeviceId id,
 116             final RemoteDeviceHandler<NetconfSessionPreferences> salFacade,
 117             final ListeningExecutorService globalProcessingExecutor, final boolean reconnectOnSchemasChange,
 118             final DeviceActionFactory deviceActionFactory, final NetconfNode node, final EventExecutor eventExecutor,
 119             final NetconfNodeAugmentedOptional nodeOptional) {
 120         this.id = id;
 121         this.reconnectOnSchemasChange = reconnectOnSchemasChange;
 122         this.deviceActionFactory = deviceActionFactory;
 123         this.node = node;
 124         this.eventExecutor = eventExecutor;
 125         this.nodeOptional = nodeOptional;
 126         this.schemaRegistry = schemaResourcesDTO.getSchemaRegistry();
 127         this.schemaRepository = schemaResourcesDTO.getSchemaRepository();
 128         this.schemaContextFactory = schemaResourcesDTO.getSchemaContextFactory();
 129         this.salFacade = salFacade;
 130         this.stateSchemasResolver = schemaResourcesDTO.getStateSchemasResolver();
 131         this.processingExecutor = requireNonNull(globalProcessingExecutor);
 132         this.notificationHandler = new NotificationHandler(salFacade, id);
 133     }
 134
 135     @Override
 136     public void onRemoteSessionUp(final NetconfSessionPreferences remoteSessionCapabilities,
 137                                   final NetconfDeviceCommunicator listener) {
 138         // SchemaContext setup has to be performed in a dedicated thread since
 139         // we are in a netty thread in this method
 140         // Yang models are being downloaded in this method and it would cause a
 141         // deadlock if we used the netty thread
 142         // http://netty.io/wiki/thread-model.html
 143         setConnected(true);
 144         LOG.debug("{}: Session to remote device established with {}", id, remoteSessionCapabilities);
 145
 146         final BaseSchema baseSchema = resolveBaseSchema(remoteSessionCapabilities.isNotificationsSupported());
 147         final NetconfDeviceRpc initRpc = new NetconfDeviceRpc(baseSchema.getSchemaContext(), listener,
 148             new NetconfMessageTransformer(baseSchema.getMountPointContext(), false, baseSchema));
 149         final ListenableFuture<DeviceSources> sourceResolverFuture = processingExecutor.submit(
 150             new DeviceSourcesResolver(id, baseSchema, initRpc, remoteSessionCapabilities, stateSchemasResolver));
 151
 152         if (shouldListenOnSchemaChange(remoteSessionCapabilities)) {
 153             registerToBaseNetconfStream(initRpc, listener);
 154         }
 155
 156         // Set up the SchemaContext for the device
 157         final ListenableFuture<SchemaContext> futureSchema = Futures.transformAsync(sourceResolverFuture, schemas -> {
 158             LOG.debug("{}: Resolved device sources to {}", id, schemas);
 159             addProvidedSourcesToSchemaRegistry(schemas);
 160             return new SchemaSetup(schemas, remoteSessionCapabilities).startResolution();
 161         }, processingExecutor);
 162
 163         // Potentially acquire mount point list and interpret it
 164         final ListenableFuture<MountPointContext> futureContext = Futures.transform(futureSchema, schemaContext -> {
 165             // FIXME: check if there is RFC8528 schema available
 166             return new EmptyMountPointContext(schemaContext);
 167         }, processingExecutor);
 168
 169         Futures.addCallback(futureContext, new FutureCallback<MountPointContext>() {
 170             @Override
 171             public void onSuccess(final MountPointContext result) {
 172                 handleSalInitializationSuccess(result, remoteSessionCapabilities,
 173                     getDeviceSpecificRpc(result, listener), listener);
 174             }
 175
 176             @Override
 177             public void onFailure(final Throwable cause) {
 178                 LOG.warn("{}: Unexpected error resolving device sources", id, cause);
 179
 180                 // No more sources, fail or try to reconnect
 181                 if (cause instanceof EmptySchemaContextException) {
 182                     if (nodeOptional != null && nodeOptional.getIgnoreMissingSchemaSources().isAllowed()) {
 183                         eventExecutor.schedule(() -> {
 184                             LOG.warn("Reconnection is allowed! This can lead to unexpected errors at runtime.");
 185                             LOG.warn("{} : No more sources for schema context.", id);
 186                             LOG.info("{} : Try to remount device.", id);
 187                             onRemoteSessionDown();
 188                             salFacade.onDeviceReconnected(remoteSessionCapabilities, node);
 189                         }, nodeOptional.getIgnoreMissingSchemaSources().getReconnectTime(), TimeUnit.MILLISECONDS);
 190                         return;
 191                     }
 192                 }
 193
 194                 handleSalInitializationFailure(cause, listener);
 195                 salFacade.onDeviceFailed(cause);
 196             }
 197         }, MoreExecutors.directExecutor());
 198     }
 199
 200     private void registerToBaseNetconfStream(final NetconfDeviceRpc deviceRpc,
 201                                              final NetconfDeviceCommunicator listener) {
 202         // TODO check whether the model describing create subscription is present in schema
 203         // Perhaps add a default schema context to support create-subscription if the model was not provided
 204         // (same as what we do for base netconf operations in transformer)
 205         final ListenableFuture<DOMRpcResult> rpcResultListenableFuture = deviceRpc.invokeRpc(
 206                 NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_PATH,
 207                 NetconfMessageTransformUtil.CREATE_SUBSCRIPTION_RPC_CONTENT);
 208
 209         Futures.addCallback(rpcResultListenableFuture, new FutureCallback<DOMRpcResult>() {
 210             @Override
 211             public void onSuccess(final DOMRpcResult domRpcResult) {
 212                 notificationHandler.addNotificationFilter(notification -> {
 213                     if (NetconfCapabilityChange.QNAME.equals(notification.getBody().getNodeType())) {
 214                         LOG.info("{}: Schemas change detected, reconnecting", id);
 215                         // Only disconnect is enough,
 216                         // the reconnecting nature of the connector will take care of reconnecting
 217                         listener.disconnect();
 218                         return Optional.empty();
 219                     }
 220                     return Optional.of(notification);
 221                 });
 222             }
 223
 224             @Override
 225             public void onFailure(final Throwable throwable) {
 226                 LOG.warn("Unable to subscribe to base notification stream. Schemas will not be reloaded on the fly",
 227                         throwable);
 228             }
 229         }, MoreExecutors.directExecutor());
 230     }
 231
 232     private boolean shouldListenOnSchemaChange(final NetconfSessionPreferences remoteSessionCapabilities) {
 233         return remoteSessionCapabilities.isNotificationsSupported() && reconnectOnSchemasChange;
 234     }
 235
 236     @SuppressFBWarnings(value = "UPM_UNCALLED_PRIVATE_METHOD",
 237             justification = "https://github.com/spotbugs/spotbugs/issues/811")
 238     private synchronized void handleSalInitializationSuccess(final MountPointContext result,
 239                                         final NetconfSessionPreferences remoteSessionCapabilities,
 240                                         final DOMRpcService deviceRpc,
 241                                         final RemoteDeviceCommunicator<NetconfMessage> listener) {
 242         //NetconfDevice.SchemaSetup can complete after NetconfDeviceCommunicator was closed. In that case do nothing,
 243         //since salFacade.onDeviceDisconnected was already called.
 244         if (connected) {
 245             final BaseSchema baseSchema =
 246                 remoteSessionCapabilities.isNotificationsSupported()
 247                         ? BaseSchema.BASE_NETCONF_CTX_WITH_NOTIFICATIONS : BaseSchema.BASE_NETCONF_CTX;
 248             this.messageTransformer = new NetconfMessageTransformer(result, true, baseSchema);
 249
 250             // salFacade.onDeviceConnected has to be called before the notification handler is initialized
 251             this.salFacade.onDeviceConnected(result, remoteSessionCapabilities, deviceRpc,
 252                     this.deviceActionFactory == null ? null : this.deviceActionFactory.createDeviceAction(
 253                             this.messageTransformer, listener, result.getSchemaContext()));
 254             this.notificationHandler.onRemoteSchemaUp(this.messageTransformer);
 255
 256             LOG.info("{}: Netconf connector initialized successfully", id);
 257         } else {
 258             LOG.warn("{}: Device communicator was closed before schema setup finished.", id);
 259         }
 260     }
 261
 262     @SuppressFBWarnings(value = "UPM_UNCALLED_PRIVATE_METHOD",
 263             justification = "https://github.com/spotbugs/spotbugs/issues/811")
 264     private void handleSalInitializationFailure(final Throwable throwable,
 265                                                 final RemoteDeviceCommunicator<NetconfMessage> listener) {
 266         LOG.error("{}: Initialization in sal failed, disconnecting from device", id, throwable);
 267         listener.close();
 268         onRemoteSessionDown();
 269         resetMessageTransformer();
 270     }
 271
 272     /**
 273      * Set the transformer to null as is in initial state.
 274      */
 275     private void resetMessageTransformer() {
 276         updateTransformer(null);
 277     }
 278
 279     private synchronized void updateTransformer(final MessageTransformer<NetconfMessage> transformer) {
 280         messageTransformer = transformer;
 281     }
 282
 283     private synchronized void setConnected(final boolean connected) {
 284         this.connected = connected;
 285     }
 286
 287     @SuppressFBWarnings(value = "UPM_UNCALLED_PRIVATE_METHOD",
 288             justification = "https://github.com/spotbugs/spotbugs/issues/811")
 289     private void addProvidedSourcesToSchemaRegistry(final DeviceSources deviceSources) {
 290         final SchemaSourceProvider<YangTextSchemaSource> yangProvider = deviceSources.getSourceProvider();
 291         for (final SourceIdentifier sourceId : deviceSources.getProvidedSources()) {
 292             sourceRegistrations.add(schemaRegistry.registerSchemaSource(yangProvider,
 293                     PotentialSchemaSource.create(
 294                             sourceId, YangTextSchemaSource.class, PotentialSchemaSource.Costs.REMOTE_IO.getValue())));
 295         }
 296     }
 297
 298     @Override
 299     public void onRemoteSessionDown() {
 300         setConnected(false);
 301         notificationHandler.onRemoteSchemaDown();
 302
 303         salFacade.onDeviceDisconnected();
 304         sourceRegistrations.forEach(SchemaSourceRegistration::close);
 305         sourceRegistrations.clear();
 306         resetMessageTransformer();
 307     }
 308
 309     @Override
 310     public void onRemoteSessionFailed(final Throwable throwable) {
 311         setConnected(false);
 312         salFacade.onDeviceFailed(throwable);
 313     }
 314
 315     @Override
 316     public void onNotification(final NetconfMessage notification) {
 317         notificationHandler.handleNotification(notification);
 318     }
 319
 320     private static BaseSchema resolveBaseSchema(final boolean notificationSupport) {
 321         return notificationSupport ? BaseSchema.BASE_NETCONF_CTX_WITH_NOTIFICATIONS : BaseSchema.BASE_NETCONF_CTX;
 322     }
 323
 324     protected NetconfDeviceRpc getDeviceSpecificRpc(final MountPointContext result,
 325             final RemoteDeviceCommunicator<NetconfMessage> listener) {
 326         return new NetconfDeviceRpc(result.getSchemaContext(), listener, new NetconfMessageTransformer(result, true));
 327     }
 328
 329     /**
 330      * Just a transfer object containing schema related dependencies. Injected in constructor.
 331      */
 332     public static class SchemaResourcesDTO {
 333         private final SchemaSourceRegistry schemaRegistry;
 334         private final SchemaRepository schemaRepository;
 335         private final SchemaContextFactory schemaContextFactory;
 336         private final NetconfDeviceSchemasResolver stateSchemasResolver;
 337
 338         public SchemaResourcesDTO(final SchemaSourceRegistry schemaRegistry,
 339                                   final SchemaRepository schemaRepository,
 340                                   final SchemaContextFactory schemaContextFactory,
 341                                   final NetconfDeviceSchemasResolver deviceSchemasResolver) {
 342             this.schemaRegistry = requireNonNull(schemaRegistry);
 343             this.schemaRepository = requireNonNull(schemaRepository);
 344             this.schemaContextFactory = requireNonNull(schemaContextFactory);
 345             this.stateSchemasResolver = requireNonNull(deviceSchemasResolver);
 346         }
 347
 348         public SchemaSourceRegistry getSchemaRegistry() {
 349             return schemaRegistry;
 350         }
 351
 352         public SchemaRepository getSchemaRepository() {
 353             return schemaRepository;
 354         }
 355
 356         public SchemaContextFactory getSchemaContextFactory() {
 357             return schemaContextFactory;
 358         }
 359
 360         public NetconfDeviceSchemasResolver getStateSchemasResolver() {
 361             return stateSchemasResolver;
 362         }
 363     }
 364
 365     /**
 366      * A dedicated exception to indicate when we fail to setup a SchemaContext.
 367      *
 368      * @author Robert Varga
 369      */
 370     private static final class EmptySchemaContextException extends Exception {
 371         private static final long serialVersionUID = 1L;
 372
 373         EmptySchemaContextException(final String message) {
 374             super(message);
 375         }
 376     }
 377
 378     /**
 379      * Schema builder that tries to build schema context from provided sources or biggest subset of it.
 380      */
 381     private final class SchemaSetup implements FutureCallback<SchemaContext> {
 382         private final SettableFuture<SchemaContext> resultFuture = SettableFuture.create();
 383
 384         private final DeviceSources deviceSources;
 385         private final NetconfSessionPreferences remoteSessionCapabilities;
 386         private final NetconfDeviceCapabilities capabilities;
 387
 388         private Collection<SourceIdentifier> requiredSources;
 389
 390         SchemaSetup(final DeviceSources deviceSources, final NetconfSessionPreferences remoteSessionCapabilities) {
 391             this.deviceSources = deviceSources;
 392             this.remoteSessionCapabilities = remoteSessionCapabilities;
 393             this.capabilities = remoteSessionCapabilities.getNetconfDeviceCapabilities();
 394
 395             requiredSources = deviceSources.getRequiredSources();
 396             final Collection<SourceIdentifier> missingSources = filterMissingSources(requiredSources);
 397
 398             capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(missingSources),
 399                     UnavailableCapability.FailureReason.MissingSource);
 400             requiredSources.removeAll(missingSources);
 401         }
 402
 403         ListenableFuture<SchemaContext> startResolution() {
 404             trySetupSchema();
 405             return resultFuture;
 406         }
 407
 408         @Override
 409         public void onSuccess(final SchemaContext result) {
 410             LOG.debug("{}: Schema context built successfully from {}", id, requiredSources);
 411
 412             final Collection<QName> filteredQNames = Sets.difference(deviceSources.getRequiredSourcesQName(),
 413                     capabilities.getUnresolvedCapabilites().keySet());
 414             capabilities.addCapabilities(filteredQNames.stream().map(entry -> new AvailableCapabilityBuilder()
 415                     .setCapability(entry.toString()).setCapabilityOrigin(
 416                             remoteSessionCapabilities.getModuleBasedCapsOrigin().get(entry)).build())
 417                     .collect(Collectors.toList()));
 418
 419             capabilities.addNonModuleBasedCapabilities(remoteSessionCapabilities
 420                     .getNonModuleCaps().stream().map(entry -> new AvailableCapabilityBuilder()
 421                             .setCapability(entry).setCapabilityOrigin(
 422                                     remoteSessionCapabilities.getNonModuleBasedCapsOrigin().get(entry)).build())
 423                     .collect(Collectors.toList()));
 424
 425             resultFuture.set(result);
 426         }
 427
 428         @Override
 429         public void onFailure(final Throwable cause) {
 430             // schemaBuilderFuture.checkedGet() throws only SchemaResolutionException
 431             // that might be wrapping a MissingSchemaSourceException so we need to look
 432             // at the cause of the exception to make sure we don't misinterpret it.
 433             if (cause instanceof MissingSchemaSourceException) {
 434                 requiredSources = handleMissingSchemaSourceException((MissingSchemaSourceException) cause);
 435             } else if (cause instanceof SchemaResolutionException) {
 436                 requiredSources = handleSchemaResolutionException((SchemaResolutionException) cause);
 437             } else {
 438                 LOG.debug("Unhandled failure", cause);
 439                 resultFuture.setException(cause);
 440                 // No more trying...
 441                 return;
 442             }
 443
 444             trySetupSchema();
 445         }
 446
 447         private void trySetupSchema() {
 448             if (!requiredSources.isEmpty()) {
 449                 // Initiate async resolution, drive it back based on the result
 450                 LOG.trace("{}: Trying to build schema context from {}", id, requiredSources);
 451                 Futures.addCallback(schemaContextFactory.createSchemaContext(requiredSources), this,
 452                     MoreExecutors.directExecutor());
 453             } else {
 454                 LOG.debug("{}: no more sources for schema context", id);
 455                 resultFuture.setException(new EmptySchemaContextException(id + ": No more sources for schema context"));
 456             }
 457         }
 458
 459         private Collection<SourceIdentifier> filterMissingSources(final Collection<SourceIdentifier> origSources) {
 460             return origSources.parallelStream().filter(sourceIdentifier -> {
 461                 try {
 462                     schemaRepository.getSchemaSource(sourceIdentifier, YangTextSchemaSource.class).get();
 463                     return false;
 464                 } catch (InterruptedException | ExecutionException e) {
 465                     return true;
 466                 }
 467             }).collect(Collectors.toList());
 468         }
 469
 470         private Collection<SourceIdentifier> handleMissingSchemaSourceException(
 471                 final MissingSchemaSourceException exception) {
 472             // In case source missing, try without it
 473             final SourceIdentifier missingSource = exception.getSourceId();
 474             LOG.warn("{}: Unable to build schema context, missing source {}, will reattempt without it",
 475                 id, missingSource);
 476             LOG.debug("{}: Unable to build schema context, missing source {}, will reattempt without it",
 477                 id, missingSource, exception);
 478             final Collection<QName> qNameOfMissingSource =
 479                 getQNameFromSourceIdentifiers(Sets.newHashSet(missingSource));
 480             if (!qNameOfMissingSource.isEmpty()) {
 481                 capabilities.addUnresolvedCapabilities(
 482                         qNameOfMissingSource, UnavailableCapability.FailureReason.MissingSource);
 483             }
 484             return stripUnavailableSource(missingSource);
 485         }
 486
 487         private Collection<SourceIdentifier> handleSchemaResolutionException(
 488                 final SchemaResolutionException resolutionException) {
 489             // In case resolution error, try only with resolved sources
 490             // There are two options why schema resolution exception occurred : unsatisfied imports or flawed model
 491             // FIXME Do we really have assurance that these two cases cannot happen at once?
 492             if (resolutionException.getFailedSource() != null) {
 493                 // flawed model - exclude it
 494                 final SourceIdentifier failedSourceId = resolutionException.getFailedSource();
 495                 LOG.warn("{}: Unable to build schema context, failed to resolve source {}, will reattempt without it",
 496                     id, failedSourceId);
 497                 LOG.warn("{}: Unable to build schema context, failed to resolve source {}, will reattempt without it",
 498                     id, failedSourceId, resolutionException);
 499                 capabilities.addUnresolvedCapabilities(
 500                         getQNameFromSourceIdentifiers(Collections.singleton(failedSourceId)),
 501                         UnavailableCapability.FailureReason.UnableToResolve);
 502                 return stripUnavailableSource(resolutionException.getFailedSource());
 503             }
 504             // unsatisfied imports
 505             final Set<SourceIdentifier> unresolvedSources = resolutionException.getUnsatisfiedImports().keySet();
 506             capabilities.addUnresolvedCapabilities(getQNameFromSourceIdentifiers(unresolvedSources),
 507                 UnavailableCapability.FailureReason.UnableToResolve);
 508             LOG.warn("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only",
 509                 id, resolutionException.getUnsatisfiedImports());
 510             LOG.debug("{}: Unable to build schema context, unsatisfied imports {}, will reattempt with resolved only",
 511                 id, resolutionException.getUnsatisfiedImports(), resolutionException);
 512             return resolutionException.getResolvedSources();
 513         }
 514
 515         private Collection<SourceIdentifier> stripUnavailableSource(final SourceIdentifier sourceIdToRemove) {
 516             final LinkedList<SourceIdentifier> sourceIdentifiers = new LinkedList<>(requiredSources);
 517             checkState(sourceIdentifiers.remove(sourceIdToRemove),
 518                     "%s: Trying to remove %s from %s failed", id, sourceIdToRemove, requiredSources);
 519             return sourceIdentifiers;
 520         }
 521
 522         private Collection<QName> getQNameFromSourceIdentifiers(final Collection<SourceIdentifier> identifiers) {
 523             final Collection<QName> qNames = Collections2.transform(identifiers, this::getQNameFromSourceIdentifier);
 524
 525             if (qNames.isEmpty()) {
 526                 LOG.debug("{}: Unable to map any source identifiers to a capability reported by device : {}", id,
 527                         identifiers);
 528             }
 529             return Collections2.filter(qNames, Predicates.notNull());
 530         }
 531
 532         private QName getQNameFromSourceIdentifier(final SourceIdentifier identifier) {
 533             // Required sources are all required and provided merged in DeviceSourcesResolver
 534             for (final QName qname : deviceSources.getRequiredSourcesQName()) {
 535                 if (!qname.getLocalName().equals(identifier.getName())) {
 536                     continue;
 537                 }
 538
 539                 if (identifier.getRevision().equals(qname.getRevision())) {
 540                     return qname;
 541                 }
 542             }
 543             LOG.warn("Unable to map identifier to a devices reported capability: {} Available: {}",identifier,
 544                     deviceSources.getRequiredSourcesQName());
 545             // return null since we cannot find the QName,
 546             // this capability will be removed from required sources and not reported as unresolved-capability
 547             return null;
 548         }
 549     }
 550 }