[GitHub] [incubator-pinot] fx19880617 commented on a change in pull request #5719: Adding support to construct pinot java client with pinot controller url

[GitBox <gi...@apache.org>]

fx19880617 commented on a change in pull request #5719:
URL: https://github.com/apache/incubator-pinot/pull/5719#discussion_r459882804



##########
File path: pinot-clients/pinot-java-client/src/main/java/org/apache/pinot/client/ControllerBasedBrokerSelector.java
##########
@@ -0,0 +1,140 @@
+/**
+ * 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.pinot.client;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.Set;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import org.apache.commons.io.IOUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.apache.pinot.client.ExternalViewReader.OFFLINE_SUFFIX;
+import static org.apache.pinot.client.ExternalViewReader.REALTIME_SUFFIX;
+
+
+public class ControllerBasedBrokerSelector implements BrokerSelector {
+  private static final Logger LOGGER = LoggerFactory.getLogger(ControllerBasedBrokerSelector.class);
+
+  public static final int DEFAULT_CONTROLLER_REQUEST_RETRIES = 3;
+  public static final long DEFAULT_CONTROLLER_REQUEST_RETRIES_INTERVAL_IN_MILLS = 5000; // 5 seconds
+  public static final long DEFAULT_CONTROLLER_REQUEST_SCHEDULE_INTERVAL_IN_MILLS = 300000; // 5 minutes
+
+  private static final String CONTROLLER_ONLINE_TABLE_BROKERS_MAP_URL_TEMPLATE = "%s/brokers/tables?state=online";
+  private static final Random RANDOM = new Random();
+  private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
+  private final String[] controllerUrls;
+  private final AtomicReference<Map<String, List<String>>> tableToBrokerListMapRef =
+      new AtomicReference<Map<String, List<String>>>();
+  private final AtomicReference<List<String>> allBrokerListRef = new AtomicReference<List<String>>();
+  private final int controllerFetchRetries;
+  private final long controllerFetchRetriesIntervalMills;
+  private final long controllerFetchScheduleIntervalMills;
+
+  public ControllerBasedBrokerSelector(String controllerUrl) {
+    this(controllerUrl, DEFAULT_CONTROLLER_REQUEST_RETRIES, DEFAULT_CONTROLLER_REQUEST_RETRIES_INTERVAL_IN_MILLS,
+        DEFAULT_CONTROLLER_REQUEST_SCHEDULE_INTERVAL_IN_MILLS);
+  }
+
+  public ControllerBasedBrokerSelector(String controllerUrl, int controllerFetchRetries,
+      long controllerFetchRetriesIntervalMills, long controllerFetchScheduleIntervalMills) {
+    this.controllerUrls = controllerUrl.split(",");
+    this.controllerFetchRetries = controllerFetchRetries;
+    this.controllerFetchRetriesIntervalMills = controllerFetchRetriesIntervalMills;
+    this.controllerFetchScheduleIntervalMills = controllerFetchScheduleIntervalMills;
+    ScheduledExecutorService scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
+    scheduledExecutorService.scheduleAtFixedRate(() -> refreshBroker(), this.controllerFetchScheduleIntervalMills,
+        this.controllerFetchScheduleIntervalMills, TimeUnit.MILLISECONDS);
+    refreshBroker();
+  }
+
+  private void refreshBroker() {
+    Map<String, List<String>> tableToBrokerListMap = getTableToBrokersMap();
+    if (tableToBrokerListMap == null) {
+      throw new RuntimeException("Unable to fetch broker information from controller");
+    }
+    tableToBrokerListMapRef.set(ImmutableMap.copyOf(tableToBrokerListMap));
+    Set<String> brokerSet = new HashSet<>();
+    for (List<String> brokerList : tableToBrokerListMap.values()) {
+      brokerSet.addAll(brokerList);
+    }
+    allBrokerListRef.set(ImmutableList.copyOf(brokerSet));
+  }
+
+  private Map<String, List<String>> getTableToBrokersMap() {
+    int controllerIdx = RANDOM.nextInt(controllerUrls.length);
+    for (int i = 0; i < controllerFetchRetries; i++) {
+      try {
+        String brokerTableQueryResp = IOUtils.toString(
+            new URL(String.format(CONTROLLER_ONLINE_TABLE_BROKERS_MAP_URL_TEMPLATE, controllerUrls[controllerIdx])));
+        Map<String, List<String>> tablesToBrokersMap = OBJECT_MAPPER.readValue(brokerTableQueryResp, Map.class);
+        for (String table : tablesToBrokersMap.keySet()) {
+          List<String> brokerHostPorts = new ArrayList<>();
+          for (String broker : tablesToBrokersMap.get(table)) {
+            brokerHostPorts.add(broker.replace("Broker_", "").replace("_", ":"));
+          }
+          tablesToBrokersMap.put(table, brokerHostPorts);
+        }
+        return tablesToBrokersMap;
+
+      } catch (Exception e) {
+        LOGGER.warn(String.format("Unable to fetch controller broker information from '%s', retry in %d millseconds",
+            controllerUrls[controllerIdx], this.controllerFetchRetriesIntervalMills), e);
+        controllerIdx = (controllerIdx + 1) % controllerUrls.length;
+        try {
+          Thread.sleep(controllerFetchRetriesIntervalMills);
+        } catch (InterruptedException interruptedException) {
+          // Swallow
+        }
+      }
+    }
+    LOGGER.warn(
+        String.format("Failed to fetch controller broker information with %d retries", this.controllerFetchRetries));
+    return null;
+  }
+
+  @Override
+  public String selectBroker(String table) {
+    if (table == null) {
+      List<String> list = allBrokerListRef.get();

Review comment:
       This is true, I'm caching the broker list with a scheduled call.  I don't want to let each query calling controller very time.




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