yang/yang-parser-impl/src/main/java/org/opendaylight/yangtools/yang/parser/repo/URLSchemaContextResolver.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.yangtools.yang.parser.repo;
   9
  10 import static com.google.common.base.Preconditions.checkArgument;
  11
  12 import com.google.common.annotations.Beta;
  13 import com.google.common.base.Objects.ToStringHelper;
  14 import com.google.common.base.Optional;
  15 import com.google.common.base.Preconditions;
  16 import com.google.common.collect.ArrayListMultimap;
  17 import com.google.common.collect.ImmutableSet;
  18 import com.google.common.collect.Multimap;
  19 import com.google.common.util.concurrent.CheckedFuture;
  20 import com.google.common.util.concurrent.Futures;
  21
  22 import java.io.IOException;
  23 import java.io.InputStream;
  24 import java.net.URL;
  25 import java.util.Collection;
  26 import java.util.concurrent.ConcurrentLinkedDeque;
  27 import java.util.concurrent.atomic.AtomicReference;
  28
  29 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  30 import org.opendaylight.yangtools.yang.model.parser.api.YangSyntaxErrorException;
  31 import org.opendaylight.yangtools.yang.model.repo.api.MissingSchemaSourceException;
  32 import org.opendaylight.yangtools.yang.model.repo.api.SchemaContextFactory;
  33 import org.opendaylight.yangtools.yang.model.repo.api.SchemaRepository;
  34 import org.opendaylight.yangtools.yang.model.repo.api.SchemaResolutionException;
  35 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceException;
  36 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceFilter;
  37 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
  38 import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
  39 import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource;
  40 import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource.Costs;
  41 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaListenerRegistration;
  42 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceProvider;
  43 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistration;
  44 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistry;
  45 import org.opendaylight.yangtools.yang.model.repo.util.InMemorySchemaSourceCache;
  46 import org.opendaylight.yangtools.yang.parser.util.ASTSchemaSource;
  47 import org.opendaylight.yangtools.yang.parser.util.TextToASTTransformer;
  48 import org.slf4j.Logger;
  49 import org.slf4j.LoggerFactory;
  50
  51 @Beta
  52 public class URLSchemaContextResolver implements AutoCloseable, SchemaSourceProvider<YangTextSchemaSource> {
  53     private static final Logger LOG = LoggerFactory.getLogger(URLSchemaContextResolver.class);
  54
  55     private final Collection<SourceIdentifier> requiredSources = new ConcurrentLinkedDeque<>();
  56     private final Multimap<SourceIdentifier, YangTextSchemaSource> texts = ArrayListMultimap.create();
  57     private final AtomicReference<Optional<SchemaContext>> currentSchemaContext =
  58             new AtomicReference<>(Optional.<SchemaContext>absent());
  59     private final InMemorySchemaSourceCache<ASTSchemaSource> cache;
  60     private final SchemaListenerRegistration transReg;
  61     private final SchemaSourceRegistry registry;
  62     private final SchemaRepository repository;
  63     private volatile Object version = new Object();
  64     private volatile Object contextVersion = version;
  65
  66
  67     private URLSchemaContextResolver(final SchemaRepository repository, final SchemaSourceRegistry registry) {
  68         this.repository = Preconditions.checkNotNull(repository);
  69         this.registry = Preconditions.checkNotNull(registry);
  70
  71         final TextToASTTransformer t = TextToASTTransformer.create(repository, registry);
  72         transReg = registry.registerSchemaSourceListener(t);
  73
  74         cache = InMemorySchemaSourceCache.createSoftCache(registry, ASTSchemaSource.class);
  75     }
  76
  77     public static URLSchemaContextResolver create(final String name) {
  78         final SharedSchemaRepository sharedRepo = new SharedSchemaRepository(name);
  79         return new URLSchemaContextResolver(sharedRepo, sharedRepo);
  80     }
  81
  82     /**
  83      * Register a URL hosting a YANG Text file.
  84      *
  85      * @param url URL
  86      * @throws YangSyntaxErrorException When the YANG file is syntactically invalid
  87      * @throws IOException when the URL is not readable
  88      * @throws SchemaSourceException When parsing encounters general error
  89      */
  90     public URLRegistration registerSource(final URL url) throws SchemaSourceException, IOException, YangSyntaxErrorException {
  91         checkArgument(url != null, "Supplied URL must not be null");
  92
  93         final SourceIdentifier guessedId = new SourceIdentifier(url.getFile(), Optional.<String>absent());
  94         final YangTextSchemaSource text = new YangTextSchemaSource(guessedId) {
  95             @Override
  96             public InputStream openStream() throws IOException {
  97                 return url.openStream();
  98             }
  99
 100             @Override
 101             protected ToStringHelper addToStringAttributes(final ToStringHelper toStringHelper) {
 102                 return toStringHelper.add("url", url);
 103             }
 104         };
 105
 106         final ASTSchemaSource ast = TextToASTTransformer.TRANSFORMATION.apply(text).checkedGet();
 107         LOG.trace("Resolved URL {} to source {}", url, ast);
 108
 109         final SourceIdentifier resolvedId = ast.getIdentifier();
 110
 111         synchronized (this) {
 112             texts.put(resolvedId, text);
 113             LOG.debug("Populated {} with text", resolvedId);
 114
 115             final SchemaSourceRegistration<YangTextSchemaSource> reg = registry.registerSchemaSource(this,
 116                 PotentialSchemaSource.create(resolvedId, YangTextSchemaSource.class, Costs.IMMEDIATE.getValue()));
 117             requiredSources.add(resolvedId);
 118             cache.schemaSourceEncountered(ast);
 119             LOG.debug("Added source {} to schema context requirements", resolvedId);
 120             version = new Object();
 121
 122             return new AbstractURLRegistration(text) {
 123                 @Override
 124                 protected void removeRegistration() {
 125                     synchronized (URLSchemaContextResolver.this) {
 126                         requiredSources.remove(resolvedId);
 127                         LOG.trace("Removed source {} from schema context requirements", resolvedId);
 128                         version = new Object();
 129                         reg.close();
 130                         texts.remove(resolvedId, text);
 131                     }
 132                 }
 133             };
 134         }
 135     }
 136
 137     /**
 138      * Try to parse all currently available yang files and build new schema context.
 139      * @return new schema context iif there is at least 1 yang file registered and
 140      *         new schema context was successfully built.
 141      */
 142     public Optional<SchemaContext> getSchemaContext() {
 143         final SchemaContextFactory factory = repository.createSchemaContextFactory(SchemaSourceFilter.ALWAYS_ACCEPT);
 144         Optional<SchemaContext> sc;
 145         Object v;
 146         do {
 147             // Spin get stable context version
 148             Object cv;
 149             do {
 150                 cv = contextVersion;
 151                 sc = currentSchemaContext.get();
 152                 if (version == cv) {
 153                     return sc;
 154                 }
 155             } while (cv != contextVersion);
 156
 157             // Version has been updated
 158             Collection<SourceIdentifier> sources;
 159             do {
 160                 v = version;
 161                 sources = ImmutableSet.copyOf(requiredSources);
 162             } while (v != version);
 163
 164             while (true) {
 165                 final CheckedFuture<SchemaContext, SchemaResolutionException> f = factory.createSchemaContext(sources);
 166                 try {
 167                     sc = Optional.of(f.checkedGet());
 168                     break;
 169                 } catch (SchemaResolutionException e) {
 170                     LOG.debug("Failed to fully assemble schema context for {}", sources, e);
 171                     sources = e.getResolvedSources();
 172                 }
 173             }
 174
 175             LOG.debug("Resolved schema context for {}", sources);
 176
 177             synchronized (this) {
 178                 if (contextVersion == cv) {
 179                     currentSchemaContext.set(sc);
 180                     contextVersion = v;
 181                 }
 182             }
 183         } while (version == v);
 184
 185         return sc;
 186     }
 187
 188     @Override
 189     public synchronized CheckedFuture<YangTextSchemaSource, SchemaSourceException> getSource(final SourceIdentifier sourceIdentifier) {
 190         final Collection<YangTextSchemaSource> ret = texts.get(sourceIdentifier);
 191
 192         LOG.debug("Lookup {} result {}", sourceIdentifier, ret);
 193         if (ret.isEmpty()) {
 194             return Futures.<YangTextSchemaSource, SchemaSourceException>immediateFailedCheckedFuture(
 195                     new MissingSchemaSourceException("URL for " + sourceIdentifier + " not registered", sourceIdentifier));
 196         }
 197
 198         return Futures.immediateCheckedFuture(ret.iterator().next());
 199     }
 200
 201     @Override
 202     public void close() {
 203         transReg.close();
 204     }
 205 }