// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// =================================================================================================
package com.twitter.common.net.http.handlers;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.annotation.Nullable;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.base.Splitter;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.net.MediaType;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
import com.google.inject.Inject;
import com.twitter.common.collections.Iterables2;
import com.twitter.common.stats.TimeSeries;
import com.twitter.common.stats.TimeSeriesRepository;
/**
* A servlet that provides time series data in JSON format.
*/
public class TimeSeriesDataSource extends HttpServlet {
@VisibleForTesting static final String TIME_METRIC = "time";
private static final String METRICS = "metrics";
private static final String SINCE = "since";
private final TimeSeriesRepository timeSeriesRepo;
private final Gson gson = new Gson();
@Inject
public TimeSeriesDataSource(TimeSeriesRepository timeSeriesRepo) {
this.timeSeriesRepo = Preconditions.checkNotNull(timeSeriesRepo);
}
@VisibleForTesting
String getResponse(
@Nullable String metricsQuery,
@Nullable String sinceQuery) throws MetricException {
if (metricsQuery == null) {
// Return metric listing.
return gson.toJson(ImmutableList.copyOf(timeSeriesRepo.getAvailableSeries()));
}
List<Iterable<Number>> tsData = Lists.newArrayList();
tsData.add(timeSeriesRepo.getTimestamps());
// Ignore requests for "time" since it is implicitly returned.
Iterable<String> names = Iterables.filter(
Splitter.on(",").split(metricsQuery),
Predicates.not(Predicates.equalTo(TIME_METRIC)));
for (String metric : names) {
TimeSeries series = timeSeriesRepo.get(metric);
if (series == null) {
JsonObject response = new JsonObject();
response.addProperty("error", "Unknown metric " + metric);
throw new MetricException(gson.toJson(response));
}
tsData.add(series.getSamples());
}
final long since = Long.parseLong(Optional.fromNullable(sinceQuery).or("0"));
Predicate<List<Number>> sinceFilter = new Predicate<List<Number>>() {
@Override public boolean apply(List<Number> next) {
return next.get(0).longValue() > since;
}
};
ResponseStruct response = new ResponseStruct(
ImmutableList.<String>builder().add(TIME_METRIC).addAll(names).build(),
FluentIterable.from(Iterables2.zip(tsData, 0)).filter(sinceFilter).toList());
return gson.toJson(response);
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType(MediaType.JSON_UTF_8.toString());
PrintWriter out = resp.getWriter();
try {
out.write(getResponse(req.getParameter(METRICS), req.getParameter(SINCE)));
} catch (MetricException e) {
resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
out.write(e.getMessage());
}
}
@VisibleForTesting
static class ResponseStruct {
// Fields must be non-final for deserialization.
List<String> names;
List<List<Number>> data;
ResponseStruct(List<String> names, List<List<Number>> data) {
this.names = names;
this.data = data;
}
}
@VisibleForTesting
static class MetricException extends Exception {
MetricException(String message) {
super(message);
}
}
}