contrib/storage-http/src/main/java/org/apache/drill/exec/store/http/HttpBatchReader.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.drill.exec.store.http;

import com.typesafe.config.Config;
import okhttp3.HttpUrl;
import okhttp3.HttpUrl.Builder;
import org.apache.drill.common.AutoCloseables;
import org.apache.drill.common.exceptions.ChildErrorContext;
import org.apache.drill.common.exceptions.CustomErrorContext;
import org.apache.drill.common.exceptions.UserException;
import org.apache.drill.exec.ExecConstants;
import org.apache.drill.exec.physical.impl.scan.framework.ManagedReader;
import org.apache.drill.exec.physical.impl.scan.framework.SchemaNegotiator;
import org.apache.drill.exec.store.easy.json.loader.JsonLoader;
import org.apache.drill.exec.store.easy.json.loader.JsonLoaderImpl.JsonLoaderBuilder;
import org.apache.drill.exec.store.http.util.HttpProxyConfig;
import org.apache.drill.exec.store.http.util.HttpProxyConfig.ProxyBuilder;
import org.apache.drill.exec.store.http.util.SimpleHttp;

import java.io.File;
import java.io.InputStream;
import java.util.List;
import java.util.Map;

public class HttpBatchReader implements ManagedReader<SchemaNegotiator> {
  private final HttpSubScan subScan;
  private final int maxRecords;
  private JsonLoader jsonLoader;
  private int recordCount;

  public HttpBatchReader(HttpSubScan subScan) {
    this.subScan = subScan;
    this.maxRecords = subScan.maxRecords();
  }

  @Override
  public boolean open(SchemaNegotiator negotiator) {

    // Result set loader setup
    String tempDirPath = negotiator
        .drillConfig()
        .getString(ExecConstants.DRILL_TMP_DIR);

    HttpUrl url = buildUrl();

    CustomErrorContext errorContext = new ChildErrorContext(negotiator.parentErrorContext()) {
      @Override
      public void addContext(UserException.Builder builder) {
        super.addContext(builder);
        builder.addContext("URL", url.toString());
      }
    };
    negotiator.setErrorContext(errorContext);

    // Http client setup
    SimpleHttp http = new SimpleHttp(
        subScan, url,
        new File(tempDirPath),
        proxySettings(negotiator.drillConfig(), url),
        errorContext);

    // JSON loader setup
    InputStream inStream = http.getInputStream();
    try {
      jsonLoader = new JsonLoaderBuilder()
          .resultSetLoader(negotiator.build())
          .standardOptions(negotiator.queryOptions())
          .dataPath(subScan.tableSpec().connectionConfig().dataPath())
          .errorContext(errorContext)
          .fromStream(inStream)
          .build();
    } catch (Throwable t) {

      // Paranoia: ensure stream is closed if anything goes wrong.
      // After this, the JSON loader will close the stream.
      AutoCloseables.closeSilently(inStream);
      throw t;
    }

    return true; // Please read the first batch
  }

  protected HttpUrl buildUrl() {
    HttpApiConfig apiConfig = subScan.tableSpec().connectionConfig();
    String baseUrl = apiConfig.url();

    // Append table name, if available.
    if (subScan.tableSpec().tableName() != null) {
      baseUrl += subScan.tableSpec().tableName();
    }
    HttpUrl.Builder urlBuilder = HttpUrl.parse(baseUrl).newBuilder();
    if (apiConfig.params() != null && !apiConfig.params().isEmpty() &&
        subScan.filters() != null) {
      addFilters(urlBuilder, apiConfig.params(), subScan.filters());
    }
    return urlBuilder.build();
  }

  /**
   * Convert equality filter conditions into HTTP query parameters
   * Parameters must appear in the order defined in the config.
   */
  protected void addFilters(Builder urlBuilder, List<String> params,
      Map<String, String> filters) {
    for (String param : params) {
      String value = filters.get(param);
      if (value != null) {
        urlBuilder.addQueryParameter(param, value);
      }
    }
  }

  protected HttpProxyConfig proxySettings(Config drillConfig, HttpUrl url) {
    final HttpStoragePluginConfig config = subScan.tableSpec().config();
    final ProxyBuilder builder = HttpProxyConfig.builder()
        .fromConfigForURL(drillConfig, url.toString());
    final String proxyType = config.proxyType();
    if (proxyType != null && !"direct".equals(proxyType)) {
      builder
        .type(config.proxyType())
        .host(config.proxyHost())
        .port(config.proxyPort())
        .username(config.proxyUsername())
        .password(config.proxyPassword());
    }
    return builder.build();
  }

  @Override
  public boolean next() {
    recordCount++;

    // Stop after the limit has been reached
    if (maxRecords >= 1 && recordCount > maxRecords) {
      return false;
    }
    return jsonLoader.readBatch();
  }

  @Override
  public void close() {
    if (jsonLoader != null) {
      jsonLoader.close();
      jsonLoader = null;
    }
  }
}