org.apache.aurora.common.net.http.handlers.VarsJsonHandler.java Source code

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Here is the source code for org.apache.aurora.common.net.http.handlers.VarsJsonHandler.java

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/**
 * 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.apache.aurora.common.net.http.handlers;

import java.util.Map;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.base.Supplier;
import com.google.common.collect.Maps;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.inject.Inject;

import org.apache.aurora.common.stats.Stat;

/**
 * A servlet that returns the current value of all variables in JSON format.
 * The format returns a JSON object with string fields and typed values:
 * <pre>
 *   {
 *     "var_a": 1,
 *     "var_b": 126.0,
 *     "var_c": "a string value",
 *   }
 * </pre>
 * If the optional URL parameter 'pretty' is used, the output will be pretty-printed
 * (similar to the above example).
 *
 * TODO(wfarner): Handle this request in VarsHandler.
 */
@Path("/vars.json")
public class VarsJsonHandler {

    private final Supplier<Iterable<Stat<?>>> statSupplier;

    /**
     * Creates a new handler that will report stats from the provided supplier.
     *
     * @param statSupplier Stats supplier.
     */
    @Inject
    public VarsJsonHandler(Supplier<Iterable<Stat<?>>> statSupplier) {
        this.statSupplier = Preconditions.checkNotNull(statSupplier);
    }

    @VisibleForTesting
    String getBody(boolean pretty) {
        Map<String, Object> vars = Maps.newLinkedHashMap();
        for (Stat<?> var : statSupplier.get()) {
            vars.put(var.getName(), var.read());
        }
        // TODO(wfarner): Let the jax-rs provider handle serialization.
        return getGson(pretty).toJson(vars);
    }

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public String getVars(@QueryParam("pretty") boolean pretty) {
        return getBody(pretty);
    }

    private Gson getGson(boolean pretty) {
        return pretty ? new GsonBuilder().setPrettyPrinting().create() : new Gson();
    }
}