Examples with Cache io.druid.client.cache.Cache used on opensource projects

Example 1 with Cache

use of io.druid.client.cache.Cache in project druid by druid-io.

the class CachingClusteredClient method run.

@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 = CacheUtil.useCacheOnBrokers(query, strategy, cacheConfig);
    final boolean populateCache = CacheUtil.populateCacheOnBrokers(query, strategy, cacheConfig);
    final boolean isBySegment = BaseQuery.getContextBySegment(query, false);
    final ImmutableMap.Builder<String, Object> contextBuilder = new ImmutableMap.Builder<>();
    final int priority = BaseQuery.getContextPriority(query, 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);
    }
    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();
    // Note that enabling this leads to putting uncovered intervals information in the response headers
    // and might blow up in some cases https://github.com/druid-io/druid/issues/2108
    int uncoveredIntervalsLimit = BaseQuery.getContextUncoveredIntervalsLimit(query, 0);
    if (uncoveredIntervalsLimit > 0) {
        List<Interval> uncoveredIntervals = Lists.newArrayListWithCapacity(uncoveredIntervalsLimit);
        boolean uncoveredIntervalsOverflowed = false;
        for (Interval interval : query.getIntervals()) {
            Iterable<TimelineObjectHolder<String, ServerSelector>> lookup = timeline.lookup(interval);
            long startMillis = interval.getStartMillis();
            long endMillis = interval.getEndMillis();
            for (TimelineObjectHolder<String, ServerSelector> holder : lookup) {
                Interval holderInterval = holder.getInterval();
                long intervalStart = holderInterval.getStartMillis();
                if (!uncoveredIntervalsOverflowed && startMillis != intervalStart) {
                    if (uncoveredIntervalsLimit > uncoveredIntervals.size()) {
                        uncoveredIntervals.add(new Interval(startMillis, intervalStart));
                    } else {
                        uncoveredIntervalsOverflowed = true;
                    }
                }
                startMillis = holderInterval.getEndMillis();
                serversLookup.add(holder);
            }
            if (!uncoveredIntervalsOverflowed && startMillis < endMillis) {
                if (uncoveredIntervalsLimit > uncoveredIntervals.size()) {
                    uncoveredIntervals.add(new Interval(startMillis, endMillis));
                } else {
                    uncoveredIntervalsOverflowed = true;
                }
            }
        }
        if (!uncoveredIntervals.isEmpty()) {
            // This returns intervals for which NO segment is present.
            // Which is not necessarily an indication that the data doesn't exist or is
            // incomplete. The data could exist and just not be loaded yet.  In either
            // case, though, this query will not include any data from the identified intervals.
            responseContext.put("uncoveredIntervals", uncoveredIntervals);
            responseContext.put("uncoveredIntervalsOverflowed", uncoveredIntervalsOverflowed);
        }
    } else {
        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);
    Map<String, Optional<RangeSet<String>>> dimensionRangeCache = Maps.newHashMap();
    // Filter unneeded chunks based on partition dimension
    for (TimelineObjectHolder<String, ServerSelector> holder : filteredServersLookup) {
        final Set<PartitionChunk<ServerSelector>> filteredChunks = DimFilterUtils.filterShards(query.getFilter(), holder.getObject(), new Function<PartitionChunk<ServerSelector>, ShardSpec>() {

            @Override
            public ShardSpec apply(PartitionChunk<ServerSelector> input) {
                return input.getObject().getSegment().getShardSpec();
            }
        }, dimensionRangeCache);
        for (PartitionChunk<ServerSelector> chunk : filteredChunks) {
            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 (// implies strategy != null
    (populateCache || useCache) && // explicit bySegment queries are never cached
    !isBySegment) {
        queryCacheKey = strategy.computeCacheKey(query);
    } else {
        queryCacheKey = null;
    }
    if (query.getContext().get(QueryResource.HDR_IF_NONE_MATCH) != null) {
        String prevEtag = (String) query.getContext().get(QueryResource.HDR_IF_NONE_MATCH);
        //compute current Etag
        Hasher hasher = Hashing.sha1().newHasher();
        boolean hasOnlyHistoricalSegments = true;
        for (Pair<ServerSelector, SegmentDescriptor> p : segments) {
            if (!p.lhs.pick().getServer().isAssignable()) {
                hasOnlyHistoricalSegments = false;
                break;
            }
            hasher.putString(p.lhs.getSegment().getIdentifier(), Charsets.UTF_8);
        }
        if (hasOnlyHistoricalSegments) {
            hasher.putBytes(queryCacheKey == null ? strategy.computeCacheKey(query) : queryCacheKey);
            String currEtag = Base64.encodeBase64String(hasher.hash().asBytes());
            responseContext.put(QueryResource.HDR_ETAG, currEtag);
            if (prevEtag.equals(currEtag)) {
                return Sequences.empty();
            }
        }
    }
    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(Iterables.limit(cacheKeys.values(), cacheConfig.getCacheBulkMergeLimit()));
        } 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 SegmentDescriptor[%s] for DataSource[%s]?! How can this be?!", segment.rhs, query.getDataSource()).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(query, sequencesByInterval);
        }

        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<T> rewrittenQuery = query.withOverriddenContext(contextBuilder.build());
            // 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) 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 = new MergeSequence(query.getResultOrdering(), 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(// 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);
            }
        }
    });
}

Example 2 with Cache

use of io.druid.client.cache.Cache in project druid by druid-io.

the class CachingQueryRunner method run.

@Override
public Sequence<T> run(Query<T> query, Map<String, Object> responseContext) {
    final CacheStrategy strategy = toolChest.getCacheStrategy(query);
    final boolean populateCache = CacheUtil.populateCacheOnDataNodes(query, strategy, cacheConfig);
    final boolean useCache = CacheUtil.useCacheOnDataNodes(query, strategy, cacheConfig);
    final Cache.NamedKey key;
    if (strategy != null && (useCache || populateCache)) {
        key = CacheUtil.computeSegmentCacheKey(segmentIdentifier, segmentDescriptor, strategy.computeCacheKey(query));
    } else {
        key = null;
    }
    if (useCache) {
        final Function cacheFn = strategy.pullFromCache();
        final byte[] cachedResult = cache.get(key);
        if (cachedResult != null) {
            final TypeReference cacheObjectClazz = strategy.getCacheObjectClazz();
            return Sequences.map(new BaseSequence<>(new BaseSequence.IteratorMaker<T, Iterator<T>>() {

                @Override
                public Iterator<T> make() {
                    try {
                        if (cachedResult.length == 0) {
                            return Iterators.emptyIterator();
                        }
                        return mapper.readValues(mapper.getFactory().createParser(cachedResult), cacheObjectClazz);
                    } catch (IOException e) {
                        throw Throwables.propagate(e);
                    }
                }

                @Override
                public void cleanup(Iterator<T> iterFromMake) {
                }
            }), cacheFn);
        }
    }
    final Collection<ListenableFuture<?>> cacheFutures = Collections.synchronizedList(Lists.<ListenableFuture<?>>newLinkedList());
    if (populateCache) {
        final Function cacheFn = strategy.prepareForCache();
        return Sequences.withEffect(Sequences.map(base.run(query, responseContext), new Function<T, T>() {

            @Override
            public T apply(final T input) {
                final SettableFuture<Object> future = SettableFuture.create();
                cacheFutures.add(future);
                backgroundExecutorService.submit(new Runnable() {

                    @Override
                    public void run() {
                        try {
                            future.set(cacheFn.apply(input));
                        } catch (Exception e) {
                            // if there is exception, should setException to quit the caching processing
                            future.setException(e);
                        }
                    }
                });
                return input;
            }
        }), new Runnable() {

            @Override
            public void run() {
                try {
                    CacheUtil.populate(cache, mapper, key, Futures.allAsList(cacheFutures).get());
                } catch (Exception e) {
                    log.error(e, "Error while getting future for cache task");
                    throw Throwables.propagate(e);
                }
            }
        }, backgroundExecutorService);
    } else {
        return base.run(query, responseContext);
    }
}

Example 3 with Cache

use of io.druid.client.cache.Cache in project druid by druid-io.

the class CachingClusteredClientTest method testCachingOverBulkLimitEnforcesLimit.

@Test
@SuppressWarnings("unchecked")
public void testCachingOverBulkLimitEnforcesLimit() throws Exception {
    final int limit = 10;
    final Interval interval = new Interval("2011-01-01/2011-01-02");
    final TimeseriesQuery query = Druids.newTimeseriesQueryBuilder().dataSource(DATA_SOURCE).intervals(new MultipleIntervalSegmentSpec(ImmutableList.of(interval))).filters(DIM_FILTER).granularity(GRANULARITY).aggregators(AGGS).postAggregators(POST_AGGS).context(CONTEXT).build();
    final Map<String, Object> context = new HashMap<>();
    final Cache cache = EasyMock.createStrictMock(Cache.class);
    final Capture<Iterable<Cache.NamedKey>> cacheKeyCapture = EasyMock.newCapture();
    EasyMock.expect(cache.getBulk(EasyMock.capture(cacheKeyCapture))).andReturn(ImmutableMap.<Cache.NamedKey, byte[]>of()).once();
    EasyMock.replay(cache);
    client = makeClient(MoreExecutors.sameThreadExecutor(), cache, limit);
    final DruidServer lastServer = servers[random.nextInt(servers.length)];
    final DataSegment dataSegment = EasyMock.createNiceMock(DataSegment.class);
    EasyMock.expect(dataSegment.getIdentifier()).andReturn(DATA_SOURCE).anyTimes();
    EasyMock.replay(dataSegment);
    final ServerSelector selector = new ServerSelector(dataSegment, new HighestPriorityTierSelectorStrategy(new RandomServerSelectorStrategy()));
    selector.addServerAndUpdateSegment(new QueryableDruidServer(lastServer, null), dataSegment);
    timeline.add(interval, "v", new SingleElementPartitionChunk<>(selector));
    client.run(query, context);
    Assert.assertTrue("Capture cache keys", cacheKeyCapture.hasCaptured());
    Assert.assertTrue("Cache key below limit", ImmutableList.copyOf(cacheKeyCapture.getValue()).size() <= limit);
    EasyMock.verify(cache);
    EasyMock.reset(cache);
    cacheKeyCapture.reset();
    EasyMock.expect(cache.getBulk(EasyMock.capture(cacheKeyCapture))).andReturn(ImmutableMap.<Cache.NamedKey, byte[]>of()).once();
    EasyMock.replay(cache);
    client = makeClient(MoreExecutors.sameThreadExecutor(), cache, 0);
    client.run(query, context);
    EasyMock.verify(cache);
    EasyMock.verify(dataSegment);
    Assert.assertTrue("Capture cache keys", cacheKeyCapture.hasCaptured());
    Assert.assertTrue("Cache Keys empty", ImmutableList.copyOf(cacheKeyCapture.getValue()).isEmpty());
}

Example 4 with Cache

use of io.druid.client.cache.Cache in project druid by druid-io.

the class CachingQueryRunnerTest method testCloseAndPopulate.

private void testCloseAndPopulate(List<Result> expectedRes, List<Result> expectedCacheRes, Query query, QueryToolChest toolchest) throws Exception {
    final AssertingClosable closable = new AssertingClosable();
    final Sequence resultSeq = Sequences.wrap(Sequences.simple(expectedRes), new SequenceWrapper() {

        @Override
        public void before() {
            Assert.assertFalse(closable.isClosed());
        }

        @Override
        public void after(boolean isDone, Throwable thrown) throws Exception {
            closable.close();
        }
    });
    final CountDownLatch cacheMustBePutOnce = new CountDownLatch(1);
    Cache cache = new Cache() {

        private final Map<NamedKey, byte[]> baseMap = new ConcurrentHashMap<>();

        @Override
        public byte[] get(NamedKey key) {
            return baseMap.get(key);
        }

        @Override
        public void put(NamedKey key, byte[] value) {
            baseMap.put(key, value);
            cacheMustBePutOnce.countDown();
        }

        @Override
        public Map<NamedKey, byte[]> getBulk(Iterable<NamedKey> keys) {
            return null;
        }

        @Override
        public void close(String namespace) {
        }

        @Override
        public CacheStats getStats() {
            return null;
        }

        @Override
        public boolean isLocal() {
            return true;
        }

        @Override
        public void doMonitor(ServiceEmitter emitter) {
        }
    };
    String segmentIdentifier = "segment";
    SegmentDescriptor segmentDescriptor = new SegmentDescriptor(new Interval("2011/2012"), "version", 0);
    DefaultObjectMapper objectMapper = new DefaultObjectMapper();
    CachingQueryRunner runner = new CachingQueryRunner(segmentIdentifier, segmentDescriptor, objectMapper, cache, toolchest, new QueryRunner() {

        @Override
        public Sequence run(Query query, Map responseContext) {
            return resultSeq;
        }
    }, backgroundExecutorService, new CacheConfig() {

        @Override
        public boolean isPopulateCache() {
            return true;
        }

        @Override
        public boolean isUseCache() {
            return true;
        }
    });
    CacheStrategy cacheStrategy = toolchest.getCacheStrategy(query);
    Cache.NamedKey cacheKey = CacheUtil.computeSegmentCacheKey(segmentIdentifier, segmentDescriptor, cacheStrategy.computeCacheKey(query));
    HashMap<String, Object> context = new HashMap<String, Object>();
    Sequence res = runner.run(query, context);
    // base sequence is not closed yet
    Assert.assertFalse("sequence must not be closed", closable.isClosed());
    Assert.assertNull("cache must be empty", cache.get(cacheKey));
    ArrayList results = Sequences.toList(res, new ArrayList());
    Assert.assertTrue(closable.isClosed());
    Assert.assertEquals(expectedRes.toString(), results.toString());
    // wait for background caching finish
    // wait at most 10 seconds to fail the test to avoid block overall tests
    Assert.assertTrue("cache must be populated", cacheMustBePutOnce.await(10, TimeUnit.SECONDS));
    byte[] cacheValue = cache.get(cacheKey);
    Assert.assertNotNull(cacheValue);
    Function<Object, Result> fn = cacheStrategy.pullFromCache();
    List<Result> cacheResults = Lists.newArrayList(Iterators.transform(objectMapper.readValues(objectMapper.getFactory().createParser(cacheValue), cacheStrategy.getCacheObjectClazz()), fn));
    Assert.assertEquals(expectedCacheRes.toString(), cacheResults.toString());
}

Example 5 with Cache

use of io.druid.client.cache.Cache in project druid by druid-io.

the class CachingQueryRunnerTest method testUseCache.

private void testUseCache(List<Result> expectedResults, Query query, QueryToolChest toolchest) throws Exception {
    DefaultObjectMapper objectMapper = new DefaultObjectMapper();
    String segmentIdentifier = "segment";
    SegmentDescriptor segmentDescriptor = new SegmentDescriptor(new Interval("2011/2012"), "version", 0);
    CacheStrategy cacheStrategy = toolchest.getCacheStrategy(query);
    Cache.NamedKey cacheKey = CacheUtil.computeSegmentCacheKey(segmentIdentifier, segmentDescriptor, cacheStrategy.computeCacheKey(query));
    Cache cache = MapCache.create(1024 * 1024);
    CacheUtil.populate(cache, objectMapper, cacheKey, Iterables.transform(expectedResults, cacheStrategy.prepareForCache()));
    CachingQueryRunner runner = new CachingQueryRunner(segmentIdentifier, segmentDescriptor, objectMapper, cache, toolchest, // return an empty sequence since results should get pulled from cache
    new QueryRunner() {

        @Override
        public Sequence run(Query query, Map responseContext) {
            return Sequences.empty();
        }
    }, backgroundExecutorService, new CacheConfig() {

        @Override
        public boolean isPopulateCache() {
            return true;
        }

        @Override
        public boolean isUseCache() {
            return true;
        }
    });
    HashMap<String, Object> context = new HashMap<String, Object>();
    List<Result> results = Sequences.toList(runner.run(query, context), new ArrayList());
    Assert.assertEquals(expectedResults.toString(), results.toString());
}