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