yang/yang-repo-spi/src/main/java/org/opendaylight/yangtools/yang/model/repo/spi/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.spi;
   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.io.Serializable;
  22 import java.util.ArrayList;
  23 import java.util.Collection;
  24 import java.util.Collections;
  25 import java.util.Comparator;
  26 import java.util.HashMap;
  27 import java.util.Iterator;
  28 import java.util.List;
  29 import java.util.Map;
  30 import org.checkerframework.checker.lock.qual.GuardedBy;
  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.SchemaSourceRepresentation;
  34 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
  35 import org.slf4j.Logger;
  36 import org.slf4j.LoggerFactory;
  37
  38 /**
  39  * Abstract base class for {@link SchemaRepository} implementations. It handles registration and lookup of schema
  40  * sources, subclasses need only to provide their own {@link #createEffectiveModelContextFactory()} implementation.
  41  */
  42 @Beta
  43 public abstract class AbstractSchemaRepository implements SchemaRepository, SchemaSourceRegistry {
  44     private static final Logger LOG = LoggerFactory.getLogger(AbstractSchemaRepository.class);
  45
  46     /*
  47      * Source identifier -> representation -> provider map. We usually are looking for
  48      * a specific representation of a source.
  49      */
  50     @GuardedBy("this")
  51     private final Map<SourceIdentifier, ListMultimap<Class<? extends SchemaSourceRepresentation>,
  52             AbstractSchemaSourceRegistration<?>>> sources = new HashMap<>();
  53
  54     /*
  55      * Schema source listeners.
  56      */
  57     @GuardedBy("this")
  58     private final List<SchemaListenerRegistration> listeners = new ArrayList<>();
  59
  60     @SuppressWarnings("unchecked")
  61     private static <T extends SchemaSourceRepresentation> ListenableFuture<T> fetchSource(
  62             final SourceIdentifier id, final Iterator<AbstractSchemaSourceRegistration<?>> it) {
  63         final AbstractSchemaSourceRegistration<?> reg = it.next();
  64
  65         return Futures.catchingAsync(((SchemaSourceProvider<T>)reg.getProvider()).getSource(id), Throwable.class,
  66             input -> {
  67                 LOG.debug("Failed to acquire source from {}", reg, input);
  68
  69                 if (it.hasNext()) {
  70                     return fetchSource(id, it);
  71                 }
  72
  73                 throw new MissingSchemaSourceException("All available providers exhausted", id, input);
  74             }, MoreExecutors.directExecutor());
  75     }
  76
  77     @Override
  78     public <T extends SchemaSourceRepresentation> ListenableFuture<T> getSchemaSource(final SourceIdentifier id,
  79             final Class<T> representation) {
  80         final ArrayList<AbstractSchemaSourceRegistration<?>> sortedSchemaSourceRegistrations;
  81
  82         synchronized (this) {
  83             final ListMultimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> srcs =
  84                 sources.get(id);
  85             if (srcs == null) {
  86                 return immediateFailedFluentFuture(new MissingSchemaSourceException(
  87                     "No providers registered for source " + id, id));
  88             }
  89
  90             sortedSchemaSourceRegistrations = Lists.newArrayList(srcs.get(representation));
  91         }
  92
  93         // TODO, remove and make sources keep sorted multimap (e.g. ArrayListMultimap with SortedLists)
  94         sortedSchemaSourceRegistrations.sort(SchemaProviderCostComparator.INSTANCE);
  95
  96         final Iterator<AbstractSchemaSourceRegistration<?>> regs = sortedSchemaSourceRegistrations.iterator();
  97         if (!regs.hasNext()) {
  98             return immediateFailedFluentFuture(new MissingSchemaSourceException(
  99                         "No providers for source " + id + " representation " + representation + " available", id));
 100         }
 101
 102         final ListenableFuture<T> fetchSourceFuture = fetchSource(id, regs);
 103         // Add callback to notify cache listeners about encountered schema
 104         Futures.addCallback(fetchSourceFuture, new FutureCallback<T>() {
 105             @Override
 106             public void onSuccess(final T result) {
 107                 for (final SchemaListenerRegistration listener : listeners) {
 108                     listener.getInstance().schemaSourceEncountered(result);
 109                 }
 110             }
 111
 112             @Override
 113             @SuppressWarnings("checkstyle:parameterName")
 114             public void onFailure(final Throwable t) {
 115                 LOG.trace("Skipping notification for encountered source {}, fetching source failed", id, t);
 116             }
 117         }, MoreExecutors.directExecutor());
 118
 119         return fetchSourceFuture;
 120     }
 121
 122     private synchronized <T extends SchemaSourceRepresentation> void addSource(final PotentialSchemaSource<T> source,
 123             final AbstractSchemaSourceRegistration<T> reg) {
 124         ListMultimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> map =
 125             sources.get(source.getSourceIdentifier());
 126         if (map == null) {
 127             map = ArrayListMultimap.create();
 128             sources.put(source.getSourceIdentifier(), map);
 129         }
 130
 131         map.put(source.getRepresentation(), reg);
 132
 133         final Collection<PotentialSchemaSource<?>> reps = Collections.singleton(source);
 134         for (SchemaListenerRegistration l : listeners) {
 135             l.getInstance().schemaSourceRegistered(reps);
 136         }
 137     }
 138
 139     private synchronized <T extends SchemaSourceRepresentation> void removeSource(final PotentialSchemaSource<?> source,
 140             final SchemaSourceRegistration<?> reg) {
 141         final Multimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> m =
 142             sources.get(source.getSourceIdentifier());
 143         if (m != null) {
 144             m.remove(source.getRepresentation(), reg);
 145
 146             for (SchemaListenerRegistration l : listeners) {
 147                 l.getInstance().schemaSourceUnregistered(source);
 148             }
 149
 150             if (m.isEmpty()) {
 151                 sources.remove(source.getSourceIdentifier());
 152             }
 153         }
 154     }
 155
 156     @Override
 157     public <T extends SchemaSourceRepresentation> SchemaSourceRegistration<T> registerSchemaSource(
 158             final SchemaSourceProvider<? super T> provider, final PotentialSchemaSource<T> source) {
 159         final PotentialSchemaSource<T> src = source.cachedReference();
 160
 161         final AbstractSchemaSourceRegistration<T> ret = new AbstractSchemaSourceRegistration<>(provider, src) {
 162             @Override
 163             protected void removeRegistration() {
 164                 removeSource(src, this);
 165             }
 166         };
 167
 168         addSource(src, ret);
 169         return ret;
 170     }
 171
 172     @Override
 173     public SchemaListenerRegistration registerSchemaSourceListener(final SchemaSourceListener listener) {
 174         final SchemaListenerRegistration ret = new AbstractSchemaListenerRegistration(listener) {
 175             @Override
 176             protected void removeRegistration() {
 177                 listeners.remove(this);
 178             }
 179         };
 180
 181         synchronized (this) {
 182             final Collection<PotentialSchemaSource<?>> col = new ArrayList<>();
 183             for (Multimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> m
 184                     : sources.values()) {
 185                 for (AbstractSchemaSourceRegistration<?> r : m.values()) {
 186                     col.add(r.getInstance());
 187                 }
 188             }
 189
 190             // Notify first, so translator-type listeners, who react by registering a source
 191             // do not cause infinite loop.
 192             listener.schemaSourceRegistered(col);
 193             listeners.add(ret);
 194         }
 195         return ret;
 196     }
 197
 198     private static class SchemaProviderCostComparator implements Comparator<AbstractSchemaSourceRegistration<?>>,
 199             Serializable {
 200         static final SchemaProviderCostComparator INSTANCE = new SchemaProviderCostComparator();
 201         private static final long serialVersionUID = 1L;
 202
 203         @Override
 204         public int compare(final AbstractSchemaSourceRegistration<?> o1, final AbstractSchemaSourceRegistration<?> o2) {
 205             return o1.getInstance().getCost() - o2.getInstance().getCost();
 206         }
 207
 208         private Object readResolve() {
 209             return INSTANCE;
 210         }
 211     }
 212 }