[GitHub] [incubator-doris] gengjun-git commented on a change in pull request #4771: [LoadBalance] make BeLoadRebalancer extends from base class Rebalancer

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

gengjun-git commented on a change in pull request #4771:
URL: https://github.com/apache/incubator-doris/pull/4771#discussion_r510138848



##########
File path: fe/fe-core/src/main/java/org/apache/doris/clone/Rebalancer.java
##########
@@ -0,0 +1,80 @@
+// 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.doris.clone;
+
+import org.apache.doris.catalog.TabletInvertedIndex;
+import org.apache.doris.clone.TabletScheduler.PathSlot;
+import org.apache.doris.system.SystemInfoService;
+import org.apache.doris.task.AgentBatchTask;
+import org.apache.doris.thrift.TStorageMedium;
+
+import com.google.common.collect.Lists;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+
+/*
+ * Rebalancer is responsible for
+ * 1. selectAlternativeTablets: selecting alternative tablets by one rebalance strategy,
+ * and return them to tablet scheduler(maybe contains the concrete moves, or maybe not).
+ * 2. createBalanceTask: given a tablet, try to create a clone task for this tablet.
+ * 3. getCachedSrcBackendId: if the rebalance strategy wants to delete the replica of a specified be,
+ * override this func.
+ * NOTICE:
+ * It may have a long interval between selectAlternativeTablets() & createBalanceTask(). So the concrete moves may be
+ * invalid when we createBalanceTask(), you should check the moves' validation.
+ */
+public abstract class Rebalancer {
+    // When Rebalancer init, the statisticMap is usually empty. So it's no need to be an arg.
+    // Only use updateLoadStatistic() to load stats.
+    protected Map<String, ClusterLoadStatistic> statisticMap = new HashMap<>();
+    protected TabletInvertedIndex invertedIndex;
+    protected SystemInfoService infoService;
+
+    public Rebalancer(SystemInfoService infoService, TabletInvertedIndex invertedIndex) {
+        this.infoService = infoService;
+        this.invertedIndex = invertedIndex;
+    }
+
+    public List<TabletSchedCtx> selectAlternativeTablets() {
+        List<TabletSchedCtx> alternativeTablets = Lists.newArrayList();
+        for (Map.Entry<String, ClusterLoadStatistic> entry : statisticMap.entrySet()) {
+            for (TStorageMedium medium : TStorageMedium.values()) {
+                alternativeTablets.addAll(selectAlternativeTabletsForCluster(entry.getKey(),
+                        entry.getValue(), medium));
+            }
+        }
+        return alternativeTablets;
+    }
+
+    protected abstract List<TabletSchedCtx> selectAlternativeTabletsForCluster(
+            String clusterName, ClusterLoadStatistic clusterStat, TStorageMedium medium);
+
+    public abstract void createBalanceTask(TabletSchedCtx tabletCtx, Map<Long, PathSlot> backendsWorkingSlots,
+                                           AgentBatchTask batchTask) throws SchedException;
+
+    public Long getCachedSrcBackendId(Long tabletId) {

Review comment:
       For current scheduler principal, a tablet can only have one task running or pending at most. So we should delete the cache as soon as possible. It is better to change this function to getAndDeleteCachedSrcBackendId. And call it after scheduler cancelled, task running cancelled, and deleteSrcReplicaOfLB.




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org



---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscribe@doris.apache.org
For additional commands, e-mail: commits-help@doris.apache.org