List of usage examples for com.google.common.collect Iterators emptyIterator
@Deprecated public static <T> UnmodifiableIterator<T> emptyIterator()
From source file:org.polarsys.reqcycle.traceability.cache.emfbased.CacheTraceabilityEngine.java
@Override protected Iterator<Pair<Link, Reachable>> doGetOneLevelTraceability(Reachable source, DIRECTION direction, Predicate<Pair<Link, Reachable>> scope) { TraceableElement s = getTraceableElement(source); if (s != null) { IPicker picker = getPicker(direction, scope); try {/*from w w w.j ava 2s. c o m*/ List<Pair<Link, Reachable>> result = new ArrayList<Pair<Link, Reachable>>(); Iterable<?> elements = picker.getNexts(source); return Lists .newArrayList(Iterables.transform(elements, new Function<Object, Pair<Link, Reachable>>() { public Pair<Link, Reachable> apply(Object o) { return (Pair<Link, Reachable>) o; } })).iterator(); } catch (PickerExecutionException e) { e.printStackTrace(); } } return Iterators.emptyIterator(); }
From source file:io.druid.client.CachingClusteredClient.java
@Override public Sequence<T> run(final Query<T> query, final Map<String, Object> responseContext) { final QueryToolChest<T, Query<T>> toolChest = warehouse.getToolChest(query); final CacheStrategy<T, Object, Query<T>> strategy = toolChest.getCacheStrategy(query); final Map<DruidServer, List<SegmentDescriptor>> serverSegments = Maps.newTreeMap(); final List<Pair<Interval, byte[]>> cachedResults = Lists.newArrayList(); final Map<String, CachePopulator> cachePopulatorMap = Maps.newHashMap(); final boolean useCache = query.getContextUseCache(true) && strategy != null && cacheConfig.isUseCache() && cacheConfig.isQueryCacheable(query); final boolean populateCache = query.getContextPopulateCache(true) && strategy != null && cacheConfig.isPopulateCache() && cacheConfig.isQueryCacheable(query); final boolean isBySegment = query.getContextBySegment(false); final ImmutableMap.Builder<String, Object> contextBuilder = new ImmutableMap.Builder<>(); final int priority = query.getContextPriority(0); contextBuilder.put("priority", priority); if (populateCache) { // prevent down-stream nodes from caching results as well if we are populating the cache contextBuilder.put(CacheConfig.POPULATE_CACHE, false); contextBuilder.put("bySegment", true); }//from w ww .j a v a2 s. co m contextBuilder.put("intermediate", true); TimelineLookup<String, ServerSelector> timeline = serverView.getTimeline(query.getDataSource()); if (timeline == null) { return Sequences.empty(); } // build set of segments to query Set<Pair<ServerSelector, SegmentDescriptor>> segments = Sets.newLinkedHashSet(); List<TimelineObjectHolder<String, ServerSelector>> serversLookup = Lists.newLinkedList(); for (Interval interval : query.getIntervals()) { Iterables.addAll(serversLookup, timeline.lookup(interval)); } // Let tool chest filter out unneeded segments final List<TimelineObjectHolder<String, ServerSelector>> filteredServersLookup = toolChest .filterSegments(query, serversLookup); for (TimelineObjectHolder<String, ServerSelector> holder : filteredServersLookup) { for (PartitionChunk<ServerSelector> chunk : holder.getObject()) { ServerSelector selector = chunk.getObject(); final SegmentDescriptor descriptor = new SegmentDescriptor(holder.getInterval(), holder.getVersion(), chunk.getChunkNumber()); segments.add(Pair.of(selector, descriptor)); } } final byte[] queryCacheKey; if ((populateCache || useCache) // implies strategy != null && !isBySegment) // explicit bySegment queries are never cached { queryCacheKey = strategy.computeCacheKey(query); } else { queryCacheKey = null; } if (queryCacheKey != null) { // cachKeys map must preserve segment ordering, in order for shards to always be combined in the same order Map<Pair<ServerSelector, SegmentDescriptor>, Cache.NamedKey> cacheKeys = Maps.newLinkedHashMap(); for (Pair<ServerSelector, SegmentDescriptor> segment : segments) { final Cache.NamedKey segmentCacheKey = CacheUtil.computeSegmentCacheKey( segment.lhs.getSegment().getIdentifier(), segment.rhs, queryCacheKey); cacheKeys.put(segment, segmentCacheKey); } // Pull cached segments from cache and remove from set of segments to query final Map<Cache.NamedKey, byte[]> cachedValues; if (useCache) { cachedValues = cache.getBulk(cacheKeys.values()); } else { cachedValues = ImmutableMap.of(); } for (Map.Entry<Pair<ServerSelector, SegmentDescriptor>, Cache.NamedKey> entry : cacheKeys.entrySet()) { Pair<ServerSelector, SegmentDescriptor> segment = entry.getKey(); Cache.NamedKey segmentCacheKey = entry.getValue(); final Interval segmentQueryInterval = segment.rhs.getInterval(); final byte[] cachedValue = cachedValues.get(segmentCacheKey); if (cachedValue != null) { // remove cached segment from set of segments to query segments.remove(segment); cachedResults.add(Pair.of(segmentQueryInterval, cachedValue)); } else if (populateCache) { // otherwise, if populating cache, add segment to list of segments to cache final String segmentIdentifier = segment.lhs.getSegment().getIdentifier(); cachePopulatorMap.put(String.format("%s_%s", segmentIdentifier, segmentQueryInterval), new CachePopulator(cache, objectMapper, segmentCacheKey)); } } } // Compile list of all segments not pulled from cache for (Pair<ServerSelector, SegmentDescriptor> segment : segments) { final QueryableDruidServer queryableDruidServer = segment.lhs.pick(); if (queryableDruidServer == null) { log.makeAlert("No servers found for %s?! How can this be?!", segment.rhs).emit(); } else { final DruidServer server = queryableDruidServer.getServer(); List<SegmentDescriptor> descriptors = serverSegments.get(server); if (descriptors == null) { descriptors = Lists.newArrayList(); serverSegments.put(server, descriptors); } descriptors.add(segment.rhs); } } return new LazySequence<>(new Supplier<Sequence<T>>() { @Override public Sequence<T> get() { ArrayList<Sequence<T>> sequencesByInterval = Lists.newArrayList(); addSequencesFromCache(sequencesByInterval); addSequencesFromServer(sequencesByInterval); return mergeCachedAndUncachedSequences(sequencesByInterval, toolChest); } private void addSequencesFromCache(ArrayList<Sequence<T>> listOfSequences) { if (strategy == null) { return; } final Function<Object, T> pullFromCacheFunction = strategy.pullFromCache(); final TypeReference<Object> cacheObjectClazz = strategy.getCacheObjectClazz(); for (Pair<Interval, byte[]> cachedResultPair : cachedResults) { final byte[] cachedResult = cachedResultPair.rhs; Sequence<Object> cachedSequence = new BaseSequence<>( new BaseSequence.IteratorMaker<Object, Iterator<Object>>() { @Override public Iterator<Object> make() { try { if (cachedResult.length == 0) { return Iterators.emptyIterator(); } return objectMapper.readValues( objectMapper.getFactory().createParser(cachedResult), cacheObjectClazz); } catch (IOException e) { throw Throwables.propagate(e); } } @Override public void cleanup(Iterator<Object> iterFromMake) { } }); listOfSequences.add(Sequences.map(cachedSequence, pullFromCacheFunction)); } } private void addSequencesFromServer(ArrayList<Sequence<T>> listOfSequences) { listOfSequences.ensureCapacity(listOfSequences.size() + serverSegments.size()); final Query<Result<BySegmentResultValueClass<T>>> rewrittenQuery = (Query<Result<BySegmentResultValueClass<T>>>) query .withOverriddenContext(contextBuilder.build()); // Loop through each server, setting up the query and initiating it. // The data gets handled as a Future and parsed in the long Sequence chain in the resultSeqToAdd setter. for (Map.Entry<DruidServer, List<SegmentDescriptor>> entry : serverSegments.entrySet()) { final DruidServer server = entry.getKey(); final List<SegmentDescriptor> descriptors = entry.getValue(); final QueryRunner clientQueryable = serverView.getQueryRunner(server); if (clientQueryable == null) { log.error("WTF!? server[%s] doesn't have a client Queryable?", server); continue; } final MultipleSpecificSegmentSpec segmentSpec = new MultipleSpecificSegmentSpec(descriptors); final Sequence<T> resultSeqToAdd; if (!server.isAssignable() || !populateCache || isBySegment) { // Direct server queryable if (!isBySegment) { resultSeqToAdd = clientQueryable.run(query.withQuerySegmentSpec(segmentSpec), responseContext); } else { // bySegment queries need to be de-serialized, see DirectDruidClient.run() @SuppressWarnings("unchecked") final Query<Result<BySegmentResultValueClass<T>>> bySegmentQuery = (Query<Result<BySegmentResultValueClass<T>>>) query; @SuppressWarnings("unchecked") final Sequence<Result<BySegmentResultValueClass<T>>> resultSequence = clientQueryable .run(bySegmentQuery.withQuerySegmentSpec(segmentSpec), responseContext); resultSeqToAdd = (Sequence) Sequences.map(resultSequence, new Function<Result<BySegmentResultValueClass<T>>, Result<BySegmentResultValueClass<T>>>() { @Override public Result<BySegmentResultValueClass<T>> apply( Result<BySegmentResultValueClass<T>> input) { final BySegmentResultValueClass<T> bySegmentValue = input.getValue(); return new Result<>(input.getTimestamp(), new BySegmentResultValueClass<T>( Lists.transform(bySegmentValue.getResults(), toolChest.makePreComputeManipulatorFn(query, MetricManipulatorFns.deserializing())), bySegmentValue.getSegmentId(), bySegmentValue.getInterval())); } }); } } else { // Requires some manipulation on broker side @SuppressWarnings("unchecked") final Sequence<Result<BySegmentResultValueClass<T>>> runningSequence = clientQueryable .run(rewrittenQuery.withQuerySegmentSpec(segmentSpec), responseContext); resultSeqToAdd = toolChest.mergeSequencesUnordered( Sequences.<Result<BySegmentResultValueClass<T>>, Sequence<T>>map(runningSequence, new Function<Result<BySegmentResultValueClass<T>>, Sequence<T>>() { private final Function<T, Object> cacheFn = strategy.prepareForCache(); // Acctually do something with the results @Override public Sequence<T> apply(Result<BySegmentResultValueClass<T>> input) { final BySegmentResultValueClass<T> value = input.getValue(); final CachePopulator cachePopulator = cachePopulatorMap .get(String.format("%s_%s", value.getSegmentId(), value.getInterval())); final Queue<ListenableFuture<Object>> cacheFutures = new ConcurrentLinkedQueue<>(); return Sequences.<T>withEffect(Sequences.<T, T>map( Sequences.<T, T>map(Sequences.<T>simple(value.getResults()), new Function<T, T>() { @Override public T apply(final T input) { if (cachePopulator != null) { // only compute cache data if populating cache cacheFutures .add(backgroundExecutorService .submit(new Callable<Object>() { @Override public Object call() { return cacheFn .apply(input); } })); } return input; } }), toolChest.makePreComputeManipulatorFn( // Ick... most makePreComputeManipulatorFn directly cast to their ToolChest query type of choice // This casting is sub-optimal, but hasn't caused any major problems yet... (Query) rewrittenQuery, MetricManipulatorFns.deserializing())), new Runnable() { @Override public void run() { if (cachePopulator != null) { Futures.addCallback( Futures.allAsList(cacheFutures), new FutureCallback<List<Object>>() { @Override public void onSuccess( List<Object> cacheData) { cachePopulator .populate(cacheData); // Help out GC by making sure all references are gone cacheFutures.clear(); } @Override public void onFailure( Throwable throwable) { log.error(throwable, "Background caching failed"); } }, backgroundExecutorService); } } }, MoreExecutors.sameThreadExecutor());// End withEffect } })); } listOfSequences.add(resultSeqToAdd); } } }// End of Supplier ); }
From source file:org.sakaiproject.nakamura.lite.content.InternalContent.java
/** * @return an iterable for all children of this content item. *//* w w w .j av a 2 s .co m*/ public Iterable<Content> listChildren() { if (newcontent) { return Iterables.emptyIterable(); } return new Iterable<Content>() { public Iterator<Content> iterator() { try { return contentManager.listChildren(path); } catch (StorageClientException e) { LOGGER.error(e.getMessage(), e); } return Iterators.emptyIterator(); } }; }
From source file:org.sakaiproject.nakamura.lite.content.InternalContent.java
/** * @return an iterable of all relative child paths of this object. *//*from w w w . j ava 2 s. c o m*/ public Iterable<String> listChildPaths() { if (newcontent) { return Iterables.emptyIterable(); } return new Iterable<String>() { public Iterator<String> iterator() { try { return contentManager.listChildPaths(path); } catch (StorageClientException e) { LOGGER.error(e.getMessage(), e); } return Iterators.emptyIterator(); } }; }
From source file:org.apache.marmotta.commons.sesame.repository.ResourceUtils.java
/** * List resources with the given prefix/*from ww w. jav a 2 s . c o m*/ * * @param prefix the prefix * @param offset * @param limit */ public static Iterable<URI> listResourcesByPrefix(final RepositoryConnection con, final String prefix, final int offset, final int limit) { final ResourceConnection rcon = getWrappedResourceConnection(con); if (rcon != null) { return new Iterable<URI>() { @Override public Iterator<URI> iterator() { try { Iterator<URI> result = ResultUtils.unwrap(rcon.getResources(prefix)); Iterators.advance(result, offset); if (limit > 0) { return Iterators.limit(result, limit); } else { return result; } } catch (RepositoryException e) { ExceptionUtils.handleRepositoryException(e, ResourceUtils.class); return Iterators.emptyIterator(); } } }; } else { // no direct prefix listing support, need to filter the listResources result return new Iterable<URI>() { @Override public Iterator<URI> iterator() { Iterator<URI> result = Iterators .transform(Iterators.filter(listResources(con).iterator(), new Predicate<Resource>() { @Override public boolean apply(Resource input) { return input instanceof URI && input.stringValue().startsWith(prefix); } }), new Function<Resource, URI>() { @Override public URI apply(Resource input) { return (URI) input; } }); Iterators.advance(result, offset); if (limit > 0) { return Iterators.limit(result, limit); } else { return result; } } }; } }
From source file:org.apache.jackrabbit.oak.spi.security.authentication.external.impl.jmx.Delegatee.java
@Nonnull private Iterator<String> internalListOrphanedIdentities() { try {// w w w .j a va 2 s. com Iterator<SyncedIdentity> it = handler.listIdentities(userMgr); return Iterators.filter(Iterators.transform(it, new Function<SyncedIdentity, String>() { @Nullable @Override public String apply(@Nullable SyncedIdentity syncedIdentity) { if (syncedIdentity != null && isMyIDP(syncedIdentity)) { ExternalIdentityRef ref = syncedIdentity.getExternalIdRef(); try { ExternalIdentity extId = (ref == null) ? null : idp.getIdentity(ref); if (extId == null) { return syncedIdentity.getId(); } } catch (ExternalIdentityException e) { log.error("Error while fetching external identity {}", syncedIdentity, e); } } return null; } }), Predicates.notNull()); } catch (RepositoryException e) { log.error("Error while listing orphaned users", e); return Iterators.emptyIterator(); } }
From source file:com.digitalpetri.opcua.sdk.server.subscriptions.Subscription.java
private void returnNotifications(ServiceRequest<PublishRequest, PublishResponse> service) { LinkedHashSet<BaseMonitoredItem<?>> items = new LinkedHashSet<>(); lastIterator.forEachRemaining(items::add); itemsById.values().stream().filter(item -> item.hasNotifications() || item.isTriggered()) .forEach(items::add);/* w w w. ja va 2 s. c o m*/ PeekingIterator<BaseMonitoredItem<?>> iterator = Iterators.peekingIterator(items.iterator()); gatherAndSend(iterator, Optional.of(service)); lastIterator = iterator.hasNext() ? iterator : Iterators.emptyIterator(); }
From source file:org.apache.jackrabbit.oak.plugins.blob.datastore.DataStoreBlobStore.java
@Override public Iterator<String> resolveChunks(String blobId) throws IOException { if (!InMemoryDataRecord.isInstance(blobId)) { return Iterators.singletonIterator(blobId); }//from www . ja v a 2s . co m return Iterators.emptyIterator(); }
From source file:org.apache.uima.lucas.indexer.analysis.AnnotationTokenStream.java
protected void initializeIterators() { annotationIterator = Iterators.filter(jCas.getAnnotationIndex(annotationType).iterator(), new NotNullPredicate<Annotation>()); if (!annotationIterator.hasNext()) { featureStructureIterator = Iterators.emptyIterator(); featureValueIterator = Iterators.emptyIterator(); return;//from www.ja v a2s . c om } currentAnnotation = (Annotation) annotationIterator.next(); featureStructureIterator = createFeatureStructureIterator(currentAnnotation, featurePath); if (!featureStructureIterator.hasNext()) { featureValueIterator = Iterators.emptyIterator(); return; } FeatureStructure featureStructure = featureStructureIterator.next(); featureValueIterator = createFeatureValueIterator(featureStructure, featureNames); }
From source file:org.apache.phoenix.execute.MutationState.java
public Iterator<Pair<byte[], List<Mutation>>> toMutations(final boolean includeMutableIndexes) { final Iterator<Map.Entry<TableRef, Map<ImmutableBytesPtr, RowMutationState>>> iterator = this.mutations .entrySet().iterator();/* w w w. j a v a 2s. co m*/ if (!iterator.hasNext()) { return Iterators.emptyIterator(); } Long scn = connection.getSCN(); final long timestamp = scn == null ? HConstants.LATEST_TIMESTAMP : scn; return new Iterator<Pair<byte[], List<Mutation>>>() { private Map.Entry<TableRef, Map<ImmutableBytesPtr, RowMutationState>> current = iterator.next(); private Iterator<Pair<byte[], List<Mutation>>> innerIterator = init(); private Iterator<Pair<byte[], List<Mutation>>> init() { return addRowMutations(current.getKey(), current.getValue(), timestamp, includeMutableIndexes); } @Override public boolean hasNext() { return innerIterator.hasNext() || iterator.hasNext(); } @Override public Pair<byte[], List<Mutation>> next() { if (!innerIterator.hasNext()) { current = iterator.next(); } return innerIterator.next(); } @Override public void remove() { throw new UnsupportedOperationException(); } }; }