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