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.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 javax.annotation.concurrent.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.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 and lookup of schema
  46  * sources, subclasses need only to provide their own {@link #createSchemaContextFactory()} implementation.
  47  */
  48 @Beta
  49 public abstract class AbstractSchemaRepository implements SchemaRepository, SchemaSourceRegistry {
  50     private static final Logger LOG = LoggerFactory.getLogger(AbstractSchemaRepository.class);
  51
  52     /*
  53      * Source identifier -> representation -> provider map. We usually are looking for
  54      * a specific representation of a source.
  55      */
  56     @GuardedBy("this")
  57     private final Map<SourceIdentifier, ListMultimap<Class<? extends SchemaSourceRepresentation>,
  58             AbstractSchemaSourceRegistration<?>>> sources = new HashMap<>();
  59
  60     /*
  61      * Schema source listeners.
  62      */
  63     @GuardedBy("this")
  64     private final List<SchemaListenerRegistration> listeners = new ArrayList<>();
  65
  66     @SuppressWarnings("unchecked")
  67     private static <T extends SchemaSourceRepresentation> ListenableFuture<T> fetchSource(
  68             final SourceIdentifier id, final Iterator<AbstractSchemaSourceRegistration<?>> it) {
  69         final AbstractSchemaSourceRegistration<?> reg = it.next();
  70
  71         return Futures.catchingAsync(((SchemaSourceProvider<T>)reg.getProvider()).getSource(id), Throwable.class,
  72             input -> {
  73                 LOG.debug("Failed to acquire source from {}", reg, input);
  74
  75                 if (it.hasNext()) {
  76                     return fetchSource(id, it);
  77                 }
  78
  79                 throw new MissingSchemaSourceException("All available providers exhausted", id, input);
  80             }, MoreExecutors.directExecutor());
  81     }
  82
  83     @Override
  84     public <T extends SchemaSourceRepresentation> ListenableFuture<T> getSchemaSource(final SourceIdentifier id,
  85             final Class<T> representation) {
  86         final ArrayList<AbstractSchemaSourceRegistration<?>> sortedSchemaSourceRegistrations;
  87
  88         synchronized (this) {
  89             final ListMultimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> srcs =
  90                 sources.get(id);
  91             if (srcs == null) {
  92                 return immediateFailedFluentFuture(new MissingSchemaSourceException(
  93                     "No providers registered for source" + id, id));
  94             }
  95
  96             sortedSchemaSourceRegistrations = Lists.newArrayList(srcs.get(representation));
  97         }
  98
  99         // TODO, remove and make sources keep sorted multimap (e.g. ArrayListMultimap with SortedLists)
 100         Collections.sort(sortedSchemaSourceRegistrations, SchemaProviderCostComparator.INSTANCE);
 101
 102         final Iterator<AbstractSchemaSourceRegistration<?>> regs = sortedSchemaSourceRegistrations.iterator();
 103         if (!regs.hasNext()) {
 104             return immediateFailedFluentFuture(new MissingSchemaSourceException(
 105                         "No providers for source " + id + " representation " + representation + " available", id));
 106         }
 107
 108         final ListenableFuture<T> fetchSourceFuture = fetchSource(id, regs);
 109         // Add callback to notify cache listeners about encountered schema
 110         Futures.addCallback(fetchSourceFuture, new FutureCallback<T>() {
 111             @Override
 112             public void onSuccess(final T result) {
 113                 for (final SchemaListenerRegistration listener : listeners) {
 114                     listener.getInstance().schemaSourceEncountered(result);
 115                 }
 116             }
 117
 118             @Override
 119             @SuppressWarnings("checkstyle:parameterName")
 120             public void onFailure(final Throwable t) {
 121                 LOG.trace("Skipping notification for encountered source {}, fetching source failed", id, t);
 122             }
 123         }, MoreExecutors.directExecutor());
 124
 125         return fetchSourceFuture;
 126     }
 127
 128     private synchronized <T extends SchemaSourceRepresentation> void addSource(final PotentialSchemaSource<T> source,
 129             final AbstractSchemaSourceRegistration<T> reg) {
 130         ListMultimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> map =
 131             sources.get(source.getSourceIdentifier());
 132         if (map == null) {
 133             map = ArrayListMultimap.create();
 134             sources.put(source.getSourceIdentifier(), map);
 135         }
 136
 137         map.put(source.getRepresentation(), reg);
 138
 139         final Collection<PotentialSchemaSource<?>> reps = Collections.singleton(source);
 140         for (SchemaListenerRegistration l : listeners) {
 141             l.getInstance().schemaSourceRegistered(reps);
 142         }
 143     }
 144
 145     private synchronized <T extends SchemaSourceRepresentation> void removeSource(final PotentialSchemaSource<?> source,
 146             final SchemaSourceRegistration<?> reg) {
 147         final Multimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> m =
 148             sources.get(source.getSourceIdentifier());
 149         if (m != null) {
 150             m.remove(source.getRepresentation(), reg);
 151
 152             for (SchemaListenerRegistration l : listeners) {
 153                 l.getInstance().schemaSourceUnregistered(source);
 154             }
 155
 156             if (m.isEmpty()) {
 157                 sources.remove(source.getSourceIdentifier());
 158             }
 159         }
 160     }
 161
 162     @Override
 163     public <T extends SchemaSourceRepresentation> SchemaSourceRegistration<T> registerSchemaSource(
 164             final SchemaSourceProvider<? super T> provider, final PotentialSchemaSource<T> source) {
 165         final PotentialSchemaSource<T> src = source.cachedReference();
 166
 167         final AbstractSchemaSourceRegistration<T> ret = new AbstractSchemaSourceRegistration<T>(provider, src) {
 168             @Override
 169             protected void removeRegistration() {
 170                 removeSource(src, this);
 171             }
 172         };
 173
 174         addSource(src, ret);
 175         return ret;
 176     }
 177
 178     @Override
 179     public SchemaListenerRegistration registerSchemaSourceListener(final SchemaSourceListener listener) {
 180         final SchemaListenerRegistration ret = new AbstractSchemaListenerRegistration(listener) {
 181             @Override
 182             protected void removeRegistration() {
 183                 listeners.remove(this);
 184             }
 185         };
 186
 187         synchronized (this) {
 188             final Collection<PotentialSchemaSource<?>> col = new ArrayList<>();
 189             for (Multimap<Class<? extends SchemaSourceRepresentation>, AbstractSchemaSourceRegistration<?>> m
 190                     : sources.values()) {
 191                 for (AbstractSchemaSourceRegistration<?> r : m.values()) {
 192                     col.add(r.getInstance());
 193                 }
 194             }
 195
 196             // Notify first, so translator-type listeners, who react by registering a source
 197             // do not cause infinite loop.
 198             listener.schemaSourceRegistered(col);
 199             listeners.add(ret);
 200         }
 201         return ret;
 202     }
 203
 204     private static class SchemaProviderCostComparator implements Comparator<AbstractSchemaSourceRegistration<?>>,
 205             Serializable {
 206         static final SchemaProviderCostComparator INSTANCE = new SchemaProviderCostComparator();
 207         private static final long serialVersionUID = 1L;
 208
 209         @Override
 210         public int compare(final AbstractSchemaSourceRegistration<?> o1, final AbstractSchemaSourceRegistration<?> o2) {
 211             return o1.getInstance().getCost() - o2.getInstance().getCost();
 212         }
 213
 214         private Object readResolve() {
 215             return INSTANCE;
 216         }
 217     }
 218 }