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