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