PerformanceMetricsResource.java

/*
 * Copyright (c) 2007-2017 MetaSolutions AB
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License 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 org.entrystore.rest.resources;

import static java.util.concurrent.TimeUnit.MILLISECONDS;

import io.micrometer.core.instrument.Meter;
import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.Metrics;
import io.micrometer.core.instrument.Timer;
import io.micrometer.core.instrument.distribution.HistogramSnapshot;
import io.micrometer.core.instrument.distribution.ValueAtPercentile;
import java.net.URI;
import org.entrystore.AuthorizationException;
import org.entrystore.PrincipalManager;
import org.json.JSONObject;
import org.restlet.data.Status;
import org.restlet.ext.json.JsonRepresentation;
import org.restlet.representation.EmptyRepresentation;
import org.restlet.representation.Representation;
import org.restlet.resource.Get;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * Provides methods to retrieve performance metrics.
 *
 */
public class PerformanceMetricsResource extends BaseResource {

    static Logger log = LoggerFactory.getLogger(PerformanceMetricsResource.class);

    /**
     * <pre>
     * GET {baseURI}/metrics
     * </pre>
     *
     * @return performance metrics
     */
    @Get
    public Representation represent() {
        try {
            MeterRegistry registry = Metrics.globalRegistry;
            PrincipalManager pm = getRM().getPrincipalManager();
            URI currentUser = pm.getAuthenticatedUserURI();

            if (!pm.getAdminUser().getURI().equals(currentUser) &&
                    !pm.getAdminGroup().isMember(pm.getUser(currentUser))) {
                getResponse().setStatus(Status.CLIENT_ERROR_FORBIDDEN);
                return new EmptyRepresentation();
            }

            JSONObject result = new JSONObject();
            for (Meter meter : registry.getMeters()) {
                // We only expose the request timers for now
                if (meter instanceof Timer timer) {
                    String timerName = timer.getId().getName();
                    HistogramSnapshot histogramSnapshot = timer.takeSnapshot();
                    JSONObject timerData = new JSONObject();
                    timerData.put("requests", histogramSnapshot.count());
                    timerData.put("mean", Math.round(histogramSnapshot.mean(MILLISECONDS)));
                    timerData.put("max", Math.round(histogramSnapshot.max(MILLISECONDS)));
                    for (ValueAtPercentile valueAtPercentile : histogramSnapshot.percentileValues()) {
                        timerData.put("percentile-" + valueAtPercentile.percentile(),
                                Math.round(valueAtPercentile.value(MILLISECONDS)));
                    }
                    result.put(timerName, timerData);
                }
            }
            return new JsonRepresentation(result.toString(2));
        } catch (AuthorizationException e) {
            return unauthorizedGET();
        } catch (Throwable e) {  //Includes JSONException
            log.error(e.getMessage());
            getResponse().setStatus(Status.SERVER_ERROR_INTERNAL);
            return new EmptyRepresentation();
        }
    }
}