yang/yang-model-util/src/main/java/org/opendaylight/yangtools/yang/model/repo/util/AbstractSchemaRepository.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.model.repo.util;
   9
  10 import com.google.common.annotations.Beta;
  11 import com.google.common.collect.ArrayListMultimap;
  12 import com.google.common.collect.ListMultimap;
  13 import com.google.common.collect.Lists;
  14 import com.google.common.collect.Multimap;
  15 import com.google.common.util.concurrent.CheckedFuture;
  16 import com.google.common.util.concurrent.FutureCallback;
  17 import com.google.common.util.concurrent.FutureFallback;
  18 import com.google.common.util.concurrent.Futures;
  19 import com.google.common.util.concurrent.ListenableFuture;
  20 import java.util.ArrayList;
  21 import java.util.Collection;
  22 import java.util.Collections;
  23 import java.util.Comparator;
  24 import java.util.HashMap;
  25 import java.util.Iterator;
  26 import java.util.Map;
  27 import javax.annotation.Nonnull;
  28 import javax.annotation.concurrent.GuardedBy;
  29 import org.opendaylight.yangtools.util.concurrent.ExceptionMapper;
  30 import org.opendaylight.yangtools.util.concurrent.ReflectiveExceptionMapper;
  31 import org.opendaylight.yangtools.yang.model.repo.api.MissingSchemaSourceException;
  32 import org.opendaylight.yangtools.yang.model.repo.api.SchemaRepository;
  33 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceException;
  34 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceFilter;
  35 import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceRepresentation;
  36 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
  37 import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource;
  38 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaListenerRegistration;
  39 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceListener;
  40 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceProvider;
  41 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistration;
  42 import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceRegistry;
  43 import org.slf4j.Logger;
  44 import org.slf4j.LoggerFactory;
  45
  46 /**
  47  * Abstract base class for {@link SchemaRepository} implementations. It handles registration
  48  * and lookup of schema sources, subclasses need only to provide their own
  49  * {@link #createSchemaContextFactory(SchemaSourceFilter)} implementation.
  50  */
  51 @Beta
  52 public abstract class AbstractSchemaRepository implements SchemaRepository, SchemaSourceRegistry {
  53     private static final Logger LOG = LoggerFactory.getLogger(AbstractSchemaRepository.class);
  54     private static final ExceptionMapper<SchemaSourceException> FETCH_MAPPER = ReflectiveExceptionMapper.create(
  55             "Schema source fetch", SchemaSourceException.class);
  56
  57     /*
  58      * Source identifier -> representation -> provider map. We usually are looking for
  59      * a specific representation of a source.
  60      */
  61     @GuardedBy("this")
  62     private final Map<SourceIdentifier, ListMultimap<Class<? extends SchemaSourceRepresentation>,
  63             AbstractSchemaSourceRegistration<?>>> sources = new HashMap<>();
  64
  65     /*
  66      * Schema source listeners.
  67      */
  68     @GuardedBy("this")
  69     private final Collection<SchemaListenerRegistration> listeners = new ArrayList<>();
  70
  71     private static <T extends SchemaSourceRepresentation> CheckedFuture<T, SchemaSourceException> fetchSource(
  72             final SourceIdentifier id, final Iterator<AbstractSchemaSourceRegistration<?>> it) {
  73         final AbstractSchemaSourceRegistration<?> reg = it.next();
  74
  75         @SuppressWarnings("unchecked")
  76         final CheckedFuture<? extends T, SchemaSourceException> f =
  77             ((SchemaSourceProvider<T>)reg.getProvider()).getSource(id);
  78
  79         return Futures.makeChecked(Futures.withFallback(f, new FutureFallback<T>() {
  80             @Override
  81             public ListenableFuture<T> create(@Nonnull final Throwable cause) throws SchemaSourceException {
  82                 LOG.debug("Failed to acquire source from {}", reg, cause);
  83
  84                 if (it.hasNext()) {
  85                     return fetchSource(id, it);
  86                 }
  87
  88                 throw new MissingSchemaSourceException("All available providers exhausted", id, cause);
  89             }
  90         }), FETCH_MAPPER);
  91     }
  92
  93     @Override
  94     public <T extends SchemaSourceRepresentation> CheckedFuture<T, SchemaSourceException> getSchemaSource(
  95             @Nonnull final SourceIdentifier id, @Nonnull final Class<T> representation) {
  96         final ArrayList<AbstractSchemaSourceRegistration<?>> sortedSchemaSourceRegistrations;
  97
  98         synchronized (this) {
  99             final ListMultimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> srcs =
 100                 sources.get(id);
 101             if (srcs == null) {
 102                 return Futures.immediateFailedCheckedFuture(new MissingSchemaSourceException(
 103                             "No providers registered for source" + id, id));
 104             }
 105
 106             sortedSchemaSourceRegistrations = Lists.newArrayList(srcs.get(representation));
 107         }
 108
 109         // TODO, remove and make sources keep sorted multimap (e.g. ArrayListMultimap with SortedLists)
 110         Collections.sort(sortedSchemaSourceRegistrations, SchemaProviderCostComparator.INSTANCE);
 111
 112         final Iterator<AbstractSchemaSourceRegistration<?>> regs = sortedSchemaSourceRegistrations.iterator();
 113         if (!regs.hasNext()) {
 114             return Futures.immediateFailedCheckedFuture(new MissingSchemaSourceException(
 115                         "No providers for source " + id + " representation " + representation + " available", id));
 116         }
 117
 118         CheckedFuture<T, SchemaSourceException> fetchSourceFuture = fetchSource(id, regs);
 119         // Add callback to notify cache listeners about encountered schema
 120         Futures.addCallback(fetchSourceFuture, new FutureCallback<T>() {
 121             @Override
 122             public void onSuccess(final T result) {
 123                 for (final SchemaListenerRegistration listener : listeners) {
 124                     listener.getInstance().schemaSourceEncountered(result);
 125                 }
 126             }
 127
 128             @Override
 129             @SuppressWarnings("checkstyle:parameterName")
 130             public void onFailure(@Nonnull final Throwable t) {
 131                 LOG.trace("Skipping notification for encountered source {}, fetching source failed", id, t);
 132             }
 133         });
 134
 135         return fetchSourceFuture;
 136     }
 137
 138     private synchronized <T extends SchemaSourceRepresentation> void addSource(final PotentialSchemaSource<T> source,
 139             final AbstractSchemaSourceRegistration<T> reg) {
 140         ListMultimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> map =
 141             sources.get(source.getSourceIdentifier());
 142         if (map == null) {
 143             map = ArrayListMultimap.create();
 144             sources.put(source.getSourceIdentifier(), map);
 145         }
 146
 147         map.put(source.getRepresentation(), reg);
 148
 149         final Collection<PotentialSchemaSource<?>> reps = Collections.singleton(source);
 150         for (SchemaListenerRegistration l : listeners) {
 151             l.getInstance().schemaSourceRegistered(reps);
 152         }
 153     }
 154
 155     private synchronized <T extends SchemaSourceRepresentation> void removeSource(final PotentialSchemaSource<?> source,
 156             final SchemaSourceRegistration<?> reg) {
 157         final Multimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> m =
 158             sources.get(source.getSourceIdentifier());
 159         if (m != null) {
 160             m.remove(source.getRepresentation(), reg);
 161
 162             for (SchemaListenerRegistration l : listeners) {
 163                 l.getInstance().schemaSourceUnregistered(source);
 164             }
 165
 166             if (m.isEmpty()) {
 167                 sources.remove(source.getSourceIdentifier());
 168             }
 169         }
 170     }
 171
 172     @Override
 173     public <T extends SchemaSourceRepresentation> SchemaSourceRegistration<T> registerSchemaSource(
 174             final SchemaSourceProvider<? super T> provider, final PotentialSchemaSource<T> source) {
 175         final PotentialSchemaSource<T> src = source.cachedReference();
 176
 177         final AbstractSchemaSourceRegistration<T> ret = new AbstractSchemaSourceRegistration<T>(provider, src) {
 178             @Override
 179             protected void removeRegistration() {
 180                 removeSource(src, this);
 181             }
 182         };
 183
 184         addSource(src, ret);
 185         return ret;
 186     }
 187
 188     @Override
 189     public SchemaListenerRegistration registerSchemaSourceListener(final SchemaSourceListener listener) {
 190         final SchemaListenerRegistration ret = new AbstractSchemaListenerRegistration(listener) {
 191             @Override
 192             protected void removeRegistration() {
 193                 listeners.remove(this);
 194             }
 195         };
 196
 197         synchronized (this) {
 198             final Collection<PotentialSchemaSource<?>> col = new ArrayList<>();
 199             for (Multimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> m
 200                     : sources.values()) {
 201                 for (AbstractSchemaSourceRegistration<?> r : m.values()) {
 202                     col.add(r.getInstance());
 203                 }
 204             }
 205
 206             // Notify first, so translator-type listeners, who react by registering a source
 207             // do not cause infinite loop.
 208             listener.schemaSourceRegistered(col);
 209             listeners.add(ret);
 210         }
 211         return ret;
 212     }
 213
 214     private static class SchemaProviderCostComparator implements Comparator<AbstractSchemaSourceRegistration<?>> {
 215         public static final SchemaProviderCostComparator INSTANCE = new SchemaProviderCostComparator();
 216
 217         @Override
 218         public int compare(final AbstractSchemaSourceRegistration<?> o1, final AbstractSchemaSourceRegistration<?> o2) {
 219             return o1.getInstance().getCost() - o2.getInstance().getCost();
 220         }
 221     }
 222 }