[GitHub] [cassandra] frankgh commented on a change in pull request #1376: CASSANDRA-17226: Consistency Level Considered Connectivity Checker

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frankgh commented on a change in pull request #1376:
URL: https://github.com/apache/cassandra/pull/1376#discussion_r804310155



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File path: src/java/org/apache/cassandra/net/ConsistencyLevelStartupConnectivityChecker.java
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@@ -0,0 +1,442 @@
+/*
+ * 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.cassandra.net;
+
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.EnumSet;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
+import java.util.function.ToIntFunction;
+import java.util.stream.Stream;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.Multimap;
+
+import org.apache.cassandra.config.DatabaseDescriptor;
+import org.apache.cassandra.db.ConsistencyLevel;
+import org.apache.cassandra.dht.Token;
+import org.apache.cassandra.locator.InetAddressAndPort;
+import org.apache.cassandra.locator.NetworkTopologyStrategy;
+import org.apache.cassandra.schema.Schema;
+import org.apache.cassandra.service.StorageService;
+import org.apache.cassandra.utils.concurrent.CountDownLatch;
+
+import static java.util.stream.Collectors.groupingBy;
+import static org.apache.cassandra.utils.concurrent.CountDownLatch.newCountDownLatch;
+
+
+/**
+ * A {@link StartupConnectivityChecker} implementation that based on the configured {@link ConsistencyLevel} to
+ * determine how many peers in the local datacenter or all datacenters to wait for before it is ready to advertise to clients.
+ * The lowest non-zero replication factor among all user keyspaces is used to determine the quorum.
+ *
+ * <p>The checker breaks the check into 2 phases.
+ * 1. In phase one, it checks if the primary set of peers has connected.
+ * 2. In phase two, it sends additional ping messages to the rest of the peers and check if the connected peers can satisfy
+ *    the specified consistency level at the end.
+ *
+ * <p>Supported values for {@code blockForPeersConsistencyLevel} are:
+ * <ul>
+ *     <li>ALL
+ *     <li>QUORUM
+ *     <li>LOCAL_QUORUM
+ *     <li>EACH_QUORUM
+ * </ul>
+ *
+ * <p>The checker only supports the {@link NetworkTopologyStrategy}. The checker is not suitable when using vnodes.
+ */
+public class ConsistencyLevelStartupConnectivityChecker
+extends AbstractStartupConnectivityChecker
+{

Review comment:
       Thanks for your review @clohfink. The drawback with this approach is that it does not establish small/large connections for the checks. Without those checks, we can only prevent unavailables and not timeouts.




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