Examples with QueryStats net.opentsdb.stats.QueryStats used on opensource projects

Example 1 with QueryStats

use of net.opentsdb.stats.QueryStats in project opentsdb by OpenTSDB.

the class TestHttpJsonSerializer method validateTestQuery.

/**
   * Helper to validate (set) the time series query
   * @param data_query The query to validate
   */
private void validateTestQuery(final TSQuery data_query) {
    data_query.validateAndSetQuery();
    data_query.setQueryStats(new QueryStats(remote, data_query, null));
}

Example 2 with QueryStats

use of net.opentsdb.stats.QueryStats in project opentsdb by OpenTSDB.

the class QueryExecutor method execute.

/**
   * Execute the RPC and serialize the response
   * @param query The HTTP query to parse and and return results to
   */
public void execute(final HttpQuery query) {
    http_query = query;
    final QueryStats query_stats = new QueryStats(query.getRemoteAddress(), ts_query, query.getHeaders());
    ts_query.setQueryStats(query_stats);
    /**
     * Sends the serialized results to the caller. This should be the very
     * last callback executed.
     */
    class CompleteCB implements Callback<Object, ChannelBuffer> {

        @Override
        public Object call(final ChannelBuffer cb) throws Exception {
            query.sendReply(cb);
            return null;
        }
    }
    /**
     * After all of the queries have run and we have data (or not) then we
     * need to compile the iterators.
     * This class could probably be improved:
     * First we iterate over the results AND for each result, iterate over
     * the expressions, giving a time synced iterator to each expression that 
     * needs the result set.
     * THEN we iterate over the expressions again and build a DAG to determine
     * if any of the expressions require the output of an expression. If so
     * then we add the expressions to the proper parent and compile them in
     * order.
     * After all of that we're ready to start serializing and iterating
     * over the results.
     */
    class QueriesCB implements Callback<Object, ArrayList<DataPoints[]>> {

        public Object call(final ArrayList<DataPoints[]> query_results) throws Exception {
            for (int i = 0; i < query_results.size(); i++) {
                final TSSubQuery sub = ts_query.getQueries().get(i);
                Iterator<Entry<String, TSSubQuery>> it = sub_queries.entrySet().iterator();
                while (it.hasNext()) {
                    final Entry<String, TSSubQuery> entry = it.next();
                    if (entry.getValue().equals(sub)) {
                        sub_query_results.put(entry.getKey(), query_results.get(i));
                        for (final ExpressionIterator ei : expressions.values()) {
                            if (ei.getVariableNames().contains(entry.getKey())) {
                                final TimeSyncedIterator tsi = new TimeSyncedIterator(entry.getKey(), sub.getFilterTagKs(), query_results.get(i));
                                final NumericFillPolicy fill = fills.get(entry.getKey());
                                if (fill != null) {
                                    tsi.setFillPolicy(fill);
                                }
                                ei.addResults(entry.getKey(), tsi);
                                if (LOG.isDebugEnabled()) {
                                    LOG.debug("Added results for " + entry.getKey() + " to " + ei.getId());
                                }
                            }
                        }
                    }
                }
            }
            // handle nested expressions
            final DirectedAcyclicGraph<String, DefaultEdge> graph = new DirectedAcyclicGraph<String, DefaultEdge>(DefaultEdge.class);
            for (final Entry<String, ExpressionIterator> eii : expressions.entrySet()) {
                if (LOG.isDebugEnabled()) {
                    LOG.debug(String.format("Expression entry key is %s, value is %s", eii.getKey(), eii.getValue().toString()));
                    LOG.debug(String.format("Time to loop through the variable names " + "for %s", eii.getKey()));
                }
                if (!graph.containsVertex(eii.getKey())) {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Adding vertex " + eii.getKey());
                    }
                    graph.addVertex(eii.getKey());
                }
                for (final String var : eii.getValue().getVariableNames()) {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug(String.format("var is %s", var));
                    }
                    final ExpressionIterator ei = expressions.get(var);
                    if (ei != null) {
                        if (LOG.isDebugEnabled()) {
                            LOG.debug(String.format("The expression iterator for %s is %s", var, ei.toString()));
                        }
                        // TODO - really ought to calculate this earlier
                        if (eii.getKey().equals(var)) {
                            throw new IllegalArgumentException("Self referencing expression found: " + eii.getKey());
                        }
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Nested expression detected. " + eii.getKey() + " depends on " + var);
                        }
                        if (!graph.containsVertex(eii.getKey())) {
                            if (LOG.isDebugEnabled()) {
                                LOG.debug("Added vertex " + eii.getKey());
                            }
                            graph.addVertex(eii.getKey());
                        } else if (LOG.isDebugEnabled()) {
                            LOG.debug("Already contains vertex " + eii.getKey());
                        }
                        if (!graph.containsVertex(var)) {
                            if (LOG.isDebugEnabled()) {
                                LOG.debug("Added vertex " + var);
                            }
                            graph.addVertex(var);
                        } else if (LOG.isDebugEnabled()) {
                            LOG.debug("Already contains vertex " + var);
                        }
                        try {
                            if (LOG.isDebugEnabled()) {
                                LOG.debug("Added Edge " + eii.getKey() + " - " + var);
                            }
                            graph.addDagEdge(eii.getKey(), var);
                        } catch (CycleFoundException cfe) {
                            throw new IllegalArgumentException("Circular reference found: " + eii.getKey(), cfe);
                        }
                    } else if (LOG.isDebugEnabled()) {
                        LOG.debug(String.format("The expression iterator for %s is null", var));
                    }
                }
            }
            // compile all of the expressions
            final long intersect_start = DateTime.currentTimeMillis();
            final Integer expressionLength = expressions.size();
            final ExpressionIterator[] compile_stack = new ExpressionIterator[expressionLength];
            final TopologicalOrderIterator<String, DefaultEdge> it = new TopologicalOrderIterator<String, DefaultEdge>(graph);
            if (LOG.isDebugEnabled()) {
                LOG.debug(String.format("Expressions Size is %d", expressionLength));
                LOG.debug(String.format("Topology Iterator %s", it.toString()));
            }
            int i = 0;
            while (it.hasNext()) {
                String next = it.next();
                if (LOG.isDebugEnabled()) {
                    LOG.debug(String.format("Expression: %s", next));
                }
                ExpressionIterator ei = expressions.get(next);
                if (LOG.isDebugEnabled()) {
                    LOG.debug(String.format("Expression Iterator: %s", ei.toString()));
                }
                if (ei == null) {
                    LOG.error(String.format("The expression iterator for %s is null", next));
                }
                compile_stack[i] = ei;
                if (LOG.isDebugEnabled()) {
                    LOG.debug(String.format("Added expression %s to compile_stack[%d]", next, i));
                }
                i++;
            }
            if (i != expressionLength) {
                throw new IOException(String.format(" Internal Error: Fewer " + "expressions where added to the compile stack than " + "expressions.size (%d instead of %d)", i, expressionLength));
            }
            if (LOG.isDebugEnabled()) {
                LOG.debug(String.format("compile stack length: %d", compile_stack.length));
            }
            for (int x = compile_stack.length - 1; x >= 0; x--) {
                if (compile_stack[x] == null) {
                    throw new NullPointerException(String.format("Item %d in " + "compile_stack[] is null", x));
                }
                // look for and add expressions
                for (final String var : compile_stack[x].getVariableNames()) {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug(String.format("Looking for variable %s for %s", var, compile_stack[x].getId()));
                    }
                    ExpressionIterator source = expressions.get(var);
                    if (source != null) {
                        compile_stack[x].addResults(var, source.getCopy());
                        if (LOG.isDebugEnabled()) {
                            LOG.debug(String.format("Adding expression %s to %s", source.getId(), compile_stack[x].getId()));
                        }
                    }
                }
                compile_stack[x].compile();
                if (LOG.isDebugEnabled()) {
                    LOG.debug(String.format("Successfully compiled %s", compile_stack[x].getId()));
                }
            }
            if (LOG.isDebugEnabled()) {
                LOG.debug("Finished compilations in " + (DateTime.currentTimeMillis() - intersect_start) + " ms");
            }
            return serialize().addCallback(new CompleteCB()).addErrback(new ErrorCB());
        }
    }
    /**
     * Callback executed after we have resolved the metric, tag names and tag
     * values to their respective UIDs. This callback then runs the actual 
     * queries and fetches their results.
     */
    class BuildCB implements Callback<Deferred<Object>, net.opentsdb.core.Query[]> {

        @Override
        public Deferred<Object> call(final net.opentsdb.core.Query[] queries) {
            final ArrayList<Deferred<DataPoints[]>> deferreds = new ArrayList<Deferred<DataPoints[]>>(queries.length);
            for (final net.opentsdb.core.Query query : queries) {
                deferreds.add(query.runAsync());
            }
            return Deferred.groupInOrder(deferreds).addCallback(new QueriesCB()).addErrback(new ErrorCB());
        }
    }
    // TODO - only run the ones that will be involved in an output. Folks WILL
    // ask for stuff they don't need.... *sigh*
    ts_query.buildQueriesAsync(tsdb).addCallback(new BuildCB()).addErrback(new ErrorCB());
}

Example 3 with QueryStats

use of net.opentsdb.stats.QueryStats in project opentsdb by OpenTSDB.

the class QueryRpc method handleQuery.

/**
   * Processing for a data point query
   * @param tsdb The TSDB to which we belong
   * @param query The HTTP query to parse/respond
   * @param allow_expressions Whether or not expressions should be parsed
   * (based on the endpoint)
   */
private void handleQuery(final TSDB tsdb, final HttpQuery query, final boolean allow_expressions) {
    final long start = DateTime.currentTimeMillis();
    final TSQuery data_query;
    final List<ExpressionTree> expressions;
    if (query.method() == HttpMethod.POST) {
        switch(query.apiVersion()) {
            case 0:
            case 1:
                data_query = query.serializer().parseQueryV1();
                break;
            default:
                query_invalid.incrementAndGet();
                throw new BadRequestException(HttpResponseStatus.NOT_IMPLEMENTED, "Requested API version not implemented", "Version " + query.apiVersion() + " is not implemented");
        }
        expressions = null;
    } else {
        expressions = new ArrayList<ExpressionTree>();
        data_query = parseQuery(tsdb, query, expressions);
    }
    if (query.getAPIMethod() == HttpMethod.DELETE && tsdb.getConfig().getBoolean("tsd.http.query.allow_delete")) {
        data_query.setDelete(true);
    }
    // validate and then compile the queries
    try {
        LOG.debug(data_query.toString());
        data_query.validateAndSetQuery();
    } catch (Exception e) {
        throw new BadRequestException(HttpResponseStatus.BAD_REQUEST, e.getMessage(), data_query.toString(), e);
    }
    // if the user tried this query multiple times from the same IP and src port
    // they'll be rejected on subsequent calls
    final QueryStats query_stats = new QueryStats(query.getRemoteAddress(), data_query, query.getPrintableHeaders());
    data_query.setQueryStats(query_stats);
    query.setStats(query_stats);
    final int nqueries = data_query.getQueries().size();
    final ArrayList<DataPoints[]> results = new ArrayList<DataPoints[]>(nqueries);
    final List<Annotation> globals = new ArrayList<Annotation>();
    /** This has to be attached to callbacks or we may never respond to clients */
    class ErrorCB implements Callback<Object, Exception> {

        public Object call(final Exception e) throws Exception {
            Throwable ex = e;
            try {
                LOG.error("Query exception: ", e);
                if (ex instanceof DeferredGroupException) {
                    ex = e.getCause();
                    while (ex != null && ex instanceof DeferredGroupException) {
                        ex = ex.getCause();
                    }
                    if (ex == null) {
                        LOG.error("The deferred group exception didn't have a cause???");
                    }
                }
                if (ex instanceof RpcTimedOutException) {
                    query_stats.markSerialized(HttpResponseStatus.REQUEST_TIMEOUT, ex);
                    query.badRequest(new BadRequestException(HttpResponseStatus.REQUEST_TIMEOUT, ex.getMessage()));
                    query_exceptions.incrementAndGet();
                } else if (ex instanceof HBaseException) {
                    query_stats.markSerialized(HttpResponseStatus.FAILED_DEPENDENCY, ex);
                    query.badRequest(new BadRequestException(HttpResponseStatus.FAILED_DEPENDENCY, ex.getMessage()));
                    query_exceptions.incrementAndGet();
                } else if (ex instanceof QueryException) {
                    query_stats.markSerialized(((QueryException) ex).getStatus(), ex);
                    query.badRequest(new BadRequestException(((QueryException) ex).getStatus(), ex.getMessage()));
                    query_exceptions.incrementAndGet();
                } else if (ex instanceof BadRequestException) {
                    query_stats.markSerialized(((BadRequestException) ex).getStatus(), ex);
                    query.badRequest((BadRequestException) ex);
                    query_invalid.incrementAndGet();
                } else if (ex instanceof NoSuchUniqueName) {
                    query_stats.markSerialized(HttpResponseStatus.BAD_REQUEST, ex);
                    query.badRequest(new BadRequestException(ex));
                    query_invalid.incrementAndGet();
                } else {
                    query_stats.markSerialized(HttpResponseStatus.INTERNAL_SERVER_ERROR, ex);
                    query.badRequest(new BadRequestException(ex));
                    query_exceptions.incrementAndGet();
                }
            } catch (RuntimeException ex2) {
                LOG.error("Exception thrown during exception handling", ex2);
                query_stats.markSerialized(HttpResponseStatus.INTERNAL_SERVER_ERROR, ex2);
                query.sendReply(HttpResponseStatus.INTERNAL_SERVER_ERROR, ex2.getMessage().getBytes());
                query_exceptions.incrementAndGet();
            }
            return null;
        }
    }
    /**
     * After all of the queries have run, we get the results in the order given
     * and add dump the results in an array
     */
    class QueriesCB implements Callback<Object, ArrayList<DataPoints[]>> {

        public Object call(final ArrayList<DataPoints[]> query_results) throws Exception {
            if (allow_expressions) {
                // process each of the expressions into a new list, then merge it
                // with the original. This avoids possible recursion loops.
                final List<DataPoints[]> expression_results = new ArrayList<DataPoints[]>(expressions.size());
                // let exceptions bubble up
                for (final ExpressionTree expression : expressions) {
                    expression_results.add(expression.evaluate(query_results));
                }
                results.addAll(expression_results);
            } else {
                results.addAll(query_results);
            }
            /** Simply returns the buffer once serialization is complete and logs it */
            class SendIt implements Callback<Object, ChannelBuffer> {

                public Object call(final ChannelBuffer buffer) throws Exception {
                    query.sendReply(buffer);
                    query_success.incrementAndGet();
                    return null;
                }
            }
            switch(query.apiVersion()) {
                case 0:
                case 1:
                    query.serializer().formatQueryAsyncV1(data_query, results, globals).addCallback(new SendIt()).addErrback(new ErrorCB());
                    break;
                default:
                    query_invalid.incrementAndGet();
                    throw new BadRequestException(HttpResponseStatus.NOT_IMPLEMENTED, "Requested API version not implemented", "Version " + query.apiVersion() + " is not implemented");
            }
            return null;
        }
    }
    /**
     * Callback executed after we have resolved the metric, tag names and tag
     * values to their respective UIDs. This callback then runs the actual 
     * queries and fetches their results.
     */
    class BuildCB implements Callback<Deferred<Object>, Query[]> {

        @Override
        public Deferred<Object> call(final Query[] queries) {
            final ArrayList<Deferred<DataPoints[]>> deferreds = new ArrayList<Deferred<DataPoints[]>>(queries.length);
            for (final Query query : queries) {
                deferreds.add(query.runAsync());
            }
            return Deferred.groupInOrder(deferreds).addCallback(new QueriesCB());
        }
    }
    /** Handles storing the global annotations after fetching them */
    class GlobalCB implements Callback<Object, List<Annotation>> {

        public Object call(final List<Annotation> annotations) throws Exception {
            globals.addAll(annotations);
            return data_query.buildQueriesAsync(tsdb).addCallback(new BuildCB());
        }
    }
    // when complete
    if (!data_query.getNoAnnotations() && data_query.getGlobalAnnotations()) {
        Annotation.getGlobalAnnotations(tsdb, data_query.startTime() / 1000, data_query.endTime() / 1000).addCallback(new GlobalCB()).addErrback(new ErrorCB());
    } else {
        data_query.buildQueriesAsync(tsdb).addCallback(new BuildCB()).addErrback(new ErrorCB());
    }
}

Example 4 with QueryStats

use of net.opentsdb.stats.QueryStats in project opentsdb by OpenTSDB.

the class HttpJsonSerializer method formatQueryAsyncV1.

/**
   * Format the results from a timeseries data query
   * @param data_query The TSQuery object used to fetch the results
   * @param results The data fetched from storage
   * @param globals An optional list of global annotation objects
   * @return A Deferred<ChannelBuffer> object to pass on to the caller
   * @throws IOException if serialization failed
   * @since 2.2
   */
public Deferred<ChannelBuffer> formatQueryAsyncV1(final TSQuery data_query, final List<DataPoints[]> results, final List<Annotation> globals) throws IOException {
    final long start = DateTime.currentTimeMillis();
    final boolean as_arrays = this.query.hasQueryStringParam("arrays");
    final String jsonp = this.query.getQueryStringParam("jsonp");
    // buffers and an array list to stored the deferreds
    final ChannelBuffer response = ChannelBuffers.dynamicBuffer();
    final OutputStream output = new ChannelBufferOutputStream(response);
    // too bad an inner class can't modify a primitive. This is a work around 
    final List<Boolean> timeout_flag = new ArrayList<Boolean>(1);
    timeout_flag.add(false);
    // start with JSONp if we're told to
    if (jsonp != null && !jsonp.isEmpty()) {
        output.write((jsonp + "(").getBytes(query.getCharset()));
    }
    // start the JSON generator and write the opening array
    final JsonGenerator json = JSON.getFactory().createGenerator(output);
    json.writeStartArray();
    /**
     * Every individual data point set (the result of a query and possibly a
     * group by) will initiate an asynchronous metric/tag UID to name resolution
     * and then print to the buffer.
     * NOTE that because this is asynchronous, the order of results is
     * indeterminate.
     */
    class DPsResolver implements Callback<Deferred<Object>, Object> {

        /** Has to be final to be shared with the nested classes */
        final StringBuilder metric = new StringBuilder(256);

        /** Resolved tags */
        final Map<String, String> tags = new HashMap<String, String>();

        /** Resolved aggregated tags */
        final List<String> agg_tags = new ArrayList<String>();

        /** A list storing the metric and tag resolve calls */
        final List<Deferred<Object>> resolve_deferreds = new ArrayList<Deferred<Object>>();

        /** The data points to serialize */
        final DataPoints dps;

        /** Starting time in nanos when we sent the UID resolution queries off */
        long uid_start;

        public DPsResolver(final DataPoints dps) {
            this.dps = dps;
        }

        /** Resolves the metric UID to a name*/
        class MetricResolver implements Callback<Object, String> {

            public Object call(final String metric) throws Exception {
                DPsResolver.this.metric.append(metric);
                return null;
            }
        }

        /** Resolves the tag UIDs to a key/value string set */
        class TagResolver implements Callback<Object, Map<String, String>> {

            public Object call(final Map<String, String> tags) throws Exception {
                DPsResolver.this.tags.putAll(tags);
                return null;
            }
        }

        /** Resolves aggregated tags */
        class AggTagResolver implements Callback<Object, List<String>> {

            public Object call(final List<String> tags) throws Exception {
                DPsResolver.this.agg_tags.addAll(tags);
                return null;
            }
        }

        /** After the metric and tags have been resolved, this will print the
       * results to the output buffer in the proper format.
       */
        class WriteToBuffer implements Callback<Object, ArrayList<Object>> {

            final DataPoints dps;

            /**
         * Default ctor that takes a data point set
         * @param dps Datapoints to print
         */
            public WriteToBuffer(final DataPoints dps) {
                this.dps = dps;
            }

            /**
         * Handles writing the data to the output buffer. The results of the
         * deferreds don't matter as they will be stored in the class final
         * variables.
         */
            public Object call(final ArrayList<Object> deferreds) throws Exception {
                data_query.getQueryStats().addStat(dps.getQueryIndex(), QueryStat.UID_TO_STRING_TIME, (DateTime.nanoTime() - uid_start));
                final long local_serialization_start = DateTime.nanoTime();
                final TSSubQuery orig_query = data_query.getQueries().get(dps.getQueryIndex());
                json.writeStartObject();
                json.writeStringField("metric", metric.toString());
                json.writeFieldName("tags");
                json.writeStartObject();
                if (dps.getTags() != null) {
                    for (Map.Entry<String, String> tag : tags.entrySet()) {
                        json.writeStringField(tag.getKey(), tag.getValue());
                    }
                }
                json.writeEndObject();
                json.writeFieldName("aggregateTags");
                json.writeStartArray();
                if (dps.getAggregatedTags() != null) {
                    for (String atag : agg_tags) {
                        json.writeString(atag);
                    }
                }
                json.writeEndArray();
                if (data_query.getShowQuery()) {
                    json.writeObjectField("query", orig_query);
                }
                if (data_query.getShowTSUIDs()) {
                    json.writeFieldName("tsuids");
                    json.writeStartArray();
                    final List<String> tsuids = dps.getTSUIDs();
                    Collections.sort(tsuids);
                    for (String tsuid : tsuids) {
                        json.writeString(tsuid);
                    }
                    json.writeEndArray();
                }
                if (!data_query.getNoAnnotations()) {
                    final List<Annotation> annotations = dps.getAnnotations();
                    if (annotations != null) {
                        Collections.sort(annotations);
                        json.writeArrayFieldStart("annotations");
                        for (Annotation note : annotations) {
                            json.writeObject(note);
                        }
                        json.writeEndArray();
                    }
                    if (globals != null && !globals.isEmpty()) {
                        Collections.sort(globals);
                        json.writeArrayFieldStart("globalAnnotations");
                        for (Annotation note : globals) {
                            json.writeObject(note);
                        }
                        json.writeEndArray();
                    }
                }
                // now the fun stuff, dump the data and time just the iteration over
                // the data points
                final long dps_start = DateTime.nanoTime();
                json.writeFieldName("dps");
                long counter = 0;
                // default is to write a map, otherwise write arrays
                if (!timeout_flag.get(0) && as_arrays) {
                    json.writeStartArray();
                    for (final DataPoint dp : dps) {
                        if (dp.timestamp() < data_query.startTime() || dp.timestamp() > data_query.endTime()) {
                            continue;
                        }
                        final long timestamp = data_query.getMsResolution() ? dp.timestamp() : dp.timestamp() / 1000;
                        json.writeStartArray();
                        json.writeNumber(timestamp);
                        if (dp.isInteger()) {
                            json.writeNumber(dp.longValue());
                        } else {
                            // Report missing intervals as null or NaN.
                            final double value = dp.doubleValue();
                            if (Double.isNaN(value) && orig_query.fillPolicy() == FillPolicy.NULL) {
                                json.writeNull();
                            } else {
                                json.writeNumber(dp.doubleValue());
                            }
                        }
                        json.writeEndArray();
                        ++counter;
                    }
                    json.writeEndArray();
                } else if (!timeout_flag.get(0)) {
                    json.writeStartObject();
                    for (final DataPoint dp : dps) {
                        if (dp.timestamp() < (data_query.startTime()) || dp.timestamp() > (data_query.endTime())) {
                            continue;
                        }
                        final long timestamp = data_query.getMsResolution() ? dp.timestamp() : dp.timestamp() / 1000;
                        if (dp.isInteger()) {
                            json.writeNumberField(Long.toString(timestamp), dp.longValue());
                        } else {
                            // Report missing intervals as null or NaN.
                            final double value = dp.doubleValue();
                            if (Double.isNaN(value) && orig_query.fillPolicy() == FillPolicy.NULL) {
                                json.writeNumberField(Long.toString(timestamp), null);
                            } else {
                                json.writeNumberField(Long.toString(timestamp), dp.doubleValue());
                            }
                        }
                        ++counter;
                    }
                    json.writeEndObject();
                } else {
                    // skipping data points all together due to timeout
                    json.writeStartObject();
                    json.writeEndObject();
                }
                final long agg_time = DateTime.nanoTime() - dps_start;
                data_query.getQueryStats().addStat(dps.getQueryIndex(), QueryStat.AGGREGATION_TIME, agg_time);
                data_query.getQueryStats().addStat(dps.getQueryIndex(), QueryStat.AGGREGATED_SIZE, counter);
                // yeah, it's a little early but we need to dump it out with the results.
                data_query.getQueryStats().addStat(dps.getQueryIndex(), QueryStat.SERIALIZATION_TIME, DateTime.nanoTime() - local_serialization_start);
                if (!timeout_flag.get(0) && data_query.getShowStats()) {
                    int query_index = (dps == null) ? -1 : dps.getQueryIndex();
                    QueryStats stats = data_query.getQueryStats();
                    if (query_index >= 0) {
                        json.writeFieldName("stats");
                        final Map<String, Object> s = stats.getQueryStats(query_index, false);
                        if (s != null) {
                            json.writeObject(s);
                        } else {
                            json.writeStringField("ERROR", "NO STATS FOUND");
                        }
                    }
                }
                // close the results for this particular query
                json.writeEndObject();
                return null;
            }
        }

        /**
       * When called, initiates a resolution of metric and tag UIDs to names, 
       * then prints to the output buffer once they are completed.
       */
        public Deferred<Object> call(final Object obj) throws Exception {
            this.uid_start = DateTime.nanoTime();
            resolve_deferreds.add(dps.metricNameAsync().addCallback(new MetricResolver()));
            resolve_deferreds.add(dps.getTagsAsync().addCallback(new TagResolver()));
            resolve_deferreds.add(dps.getAggregatedTagsAsync().addCallback(new AggTagResolver()));
            return Deferred.group(resolve_deferreds).addCallback(new WriteToBuffer(dps));
        }
    }
    // We want the serializer to execute serially so we need to create a callback
    // chain so that when one DPsResolver is finished, it triggers the next to
    // start serializing.
    final Deferred<Object> cb_chain = new Deferred<Object>();
    for (DataPoints[] separate_dps : results) {
        for (DataPoints dps : separate_dps) {
            try {
                cb_chain.addCallback(new DPsResolver(dps));
            } catch (Exception e) {
                throw new RuntimeException("Unexpected error durring resolution", e);
            }
        }
    }
    /** Final callback to close out the JSON array and return our results */
    class FinalCB implements Callback<ChannelBuffer, Object> {

        public ChannelBuffer call(final Object obj) throws Exception {
            // Call this here so we rollup sub metrics into a summary. It's not
            // completely accurate, of course, because we still have to write the
            // summary and close the writer. But it's close.
            data_query.getQueryStats().markSerializationSuccessful();
            // TODO - yeah, I've heard this sucks, we need to figure out a better way.
            if (data_query.getShowSummary()) {
                final QueryStats stats = data_query.getQueryStats();
                json.writeStartObject();
                json.writeFieldName("statsSummary");
                json.writeObject(stats.getStats(true, true));
                json.writeEndObject();
            }
            // IMPORTANT Make sure the close the JSON array and the generator
            json.writeEndArray();
            json.close();
            if (jsonp != null && !jsonp.isEmpty()) {
                output.write(")".getBytes());
            }
            return response;
        }
    }
    // trigger the callback chain here
    cb_chain.callback(null);
    return cb_chain.addCallback(new FinalCB());
}