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