co.cask.cdap.explore.executor.AbstractExploreMetadataHttpHandler.java Source code

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Here is the source code for co.cask.cdap.explore.executor.AbstractExploreMetadataHttpHandler.java

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/*
 * Copyright  2015 Cask Data, Inc.
 * 
 * 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 co.cask.cdap.explore.executor;

import co.cask.cdap.explore.service.ExploreException;
import co.cask.cdap.proto.QueryHandle;
import co.cask.http.AbstractHttpHandler;
import co.cask.http.HttpResponder;
import com.google.common.base.Charsets;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
import com.google.gson.JsonSyntaxException;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBufferInputStream;
import org.jboss.netty.handler.codec.http.HttpRequest;
import org.jboss.netty.handler.codec.http.HttpResponseStatus;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.sql.SQLException;

/**
 * An abstract class that provides common functionality for namespaced and non-namespaced ExploreMetadata handlers.
 */
public class AbstractExploreMetadataHttpHandler extends AbstractHttpHandler {
    private static final Logger LOG = LoggerFactory.getLogger(AbstractExploreMetadataHttpHandler.class);
    private static final Gson GSON = new Gson();

    protected void handleResponseEndpointExecution(HttpRequest request, HttpResponder responder,
            final EndpointCoreExecution<QueryHandle> execution) throws ExploreException, IOException {
        genericEndpointExecution(request, responder, new EndpointCoreExecution<Void>() {
            @Override
            public Void execute(HttpRequest request, HttpResponder responder)
                    throws IllegalArgumentException, SQLException, ExploreException, IOException {
                QueryHandle handle = execution.execute(request, responder);
                JsonObject json = new JsonObject();
                json.addProperty("handle", handle.getHandle());
                responder.sendJson(HttpResponseStatus.OK, json);
                return null;
            }
        });
    }

    protected void genericEndpointExecution(HttpRequest request, HttpResponder responder,
            EndpointCoreExecution<Void> execution) throws ExploreException, IOException {
        try {
            execution.execute(request, responder);
        } catch (IllegalArgumentException e) {
            LOG.debug("Got exception:", e);
            responder.sendString(HttpResponseStatus.BAD_REQUEST, e.getMessage());
        } catch (SQLException e) {
            LOG.debug("Got exception:", e);
            responder.sendString(HttpResponseStatus.BAD_REQUEST,
                    String.format("[SQLState %s] %s", e.getSQLState(), e.getMessage()));
        }
    }

    protected <T> T decodeArguments(HttpRequest request, Class<T> argsType, T defaultValue) throws IOException {
        ChannelBuffer content = request.getContent();
        if (!content.readable()) {
            return defaultValue;
        }
        try (Reader reader = new InputStreamReader(new ChannelBufferInputStream(content), Charsets.UTF_8)) {
            T args = GSON.fromJson(reader, argsType);
            return (args == null) ? defaultValue : args;
        } catch (JsonSyntaxException e) {
            LOG.info("Failed to parse runtime arguments on {}", request.getUri(), e);
            throw e;
        }
    }

    /**
     * Represents the core execution of an endpoint.
     */
    protected interface EndpointCoreExecution<T> {
        T execute(HttpRequest request, HttpResponder responder)
                throws IllegalArgumentException, SQLException, ExploreException, IOException;
    }

}