optimize: Caching the ConsistentHashSelector to avoid remapping when …

…select every time.
apache · Dec 23, 2024 · 136d2f9 · 136d2f9
1 parent 87885a3
commit 136d2f9
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Showing 2 changed files with 33 additions and 19 deletions.
diff --git a/...-core/src/main/java/org/apache/seata/discovery/loadbalance/ConsistentHashLoadBalance.java b/...-core/src/main/java/org/apache/seata/discovery/loadbalance/ConsistentHashLoadBalance.java
@@ -19,9 +19,7 @@
 import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
-import java.util.List;
-import java.util.SortedMap;
-import java.util.TreeMap;
+import java.util.*;
 
 import org.apache.seata.common.loader.LoadLevel;
 import org.apache.seata.config.ConfigurationFactory;
@@ -38,26 +36,26 @@ public class ConsistentHashLoadBalance implements LoadBalance {
      * The constant LOAD_BALANCE_CONSISTENT_HASH_VIRTUAL_NODES.
      */
     public static final String LOAD_BALANCE_CONSISTENT_HASH_VIRTUAL_NODES = LoadBalanceFactory.LOAD_BALANCE_PREFIX
-        + "virtualNodes";
+            + "virtualNodes";
     /**
      * The constant VIRTUAL_NODES_NUM.
      */
     private static final int VIRTUAL_NODES_NUM = ConfigurationFactory.getInstance().getInt(
-        LOAD_BALANCE_CONSISTENT_HASH_VIRTUAL_NODES, VIRTUAL_NODES_DEFAULT);
+            LOAD_BALANCE_CONSISTENT_HASH_VIRTUAL_NODES, VIRTUAL_NODES_DEFAULT);
 
     /**
      * The ConsistentHashSelectorWrapper that caches a {@link ConsistentHashSelector}.
      */
     private volatile ConsistentHashSelectorWrapper selectorWrapper;
 
-    @Override
     @SuppressWarnings("unchecked")
+    @Override
     public <T> T select(List<T> invokers, String xid) {
         if (selectorWrapper == null) {
             synchronized (this) {
                 if (selectorWrapper == null) {
                     selectorWrapper = new ConsistentHashSelectorWrapper(
-                            new ConsistentHashSelector<>(invokers, VIRTUAL_NODES_NUM), invokers.hashCode());
+                            new ConsistentHashSelector<>(invokers, VIRTUAL_NODES_NUM), invokers);
                 }
             }
         }
@@ -68,25 +66,37 @@ public <T> T select(List<T> invokers, String xid) {
     private static final class ConsistentHashSelectorWrapper {
 
         private volatile ConsistentHashSelector selector;
-        private volatile int invokersHashcode;
+        // only shared with read
+        private volatile Set invokers;
 
-        public ConsistentHashSelectorWrapper(ConsistentHashSelector selector, int invokersHashcode) {
+        public ConsistentHashSelectorWrapper(ConsistentHashSelector selector, List invokers) {
             this.selector = selector;
-            this.invokersHashcode = invokersHashcode;
+            this.invokers = new HashSet<>(invokers);
         }
 
         public ConsistentHashSelector getSelector(List invokers) {
-            int hashCode;
-            if ((hashCode = invokers.hashCode()) != invokersHashcode) {
+            if (!equals(invokers)) {
                 synchronized (this) {
-                    if (hashCode != invokersHashcode) {
+                    if (!equals(invokers)) {
                         selector = new ConsistentHashSelector(invokers, VIRTUAL_NODES_NUM);
-                        invokersHashcode = hashCode;
+                        this.invokers = new HashSet<>(invokers);
                     }
                 }
             }
             return selector;
         }
+
+        private boolean equals(List invokers) {
+            if (invokers.size() != this.invokers.size()) {
+                return false;
+            }
+            for (Object invoker : invokers) {
+                if (!this.invokers.contains(invoker)) {
+                    return false;
+                }
+            }
+            return true;
+        }
     }
 
     private static final class ConsistentHashSelector<T> {

diff --git a/...-discovery-core/src/test/java/org/apache/seata/discovery/loadbalance/LoadBalanceTest.java b/...-discovery-core/src/test/java/org/apache/seata/discovery/loadbalance/LoadBalanceTest.java
@@ -120,14 +120,18 @@ public void testConsistentHashLoadBalance_select(List<InetSocketAddress> address
     @MethodSource("addressProvider")
     public void testCachedConsistentHashLoadBalance_select(List<InetSocketAddress> addresses) throws Exception {
         ConsistentHashLoadBalance loadBalance = new ConsistentHashLoadBalance();
-        loadBalance.select(addresses, XID);
+
+        List<InetSocketAddress> addresses1 = new ArrayList<>(addresses);
+        loadBalance.select(addresses1, XID);
         Object o1 = getConsistentHashSelectorByReflect(loadBalance);
-        loadBalance.select(addresses, XID);
+        List<InetSocketAddress> addresses2 = new ArrayList<>(addresses);
+        loadBalance.select(addresses2, XID);
         Object o2 = getConsistentHashSelectorByReflect(loadBalance);
         Assertions.assertEquals(o1, o2);
-        addresses = new ArrayList<>(addresses);
-        addresses.remove(ThreadLocalRandom.current().nextInt(addresses.size()));
-        loadBalance.select(addresses, XID);
+
+        List<InetSocketAddress> addresses3 = new ArrayList<>(addresses);
+        addresses3.remove(ThreadLocalRandom.current().nextInt(addresses.size()));
+        loadBalance.select(addresses3, XID);
         Object o3 = getConsistentHashSelectorByReflect(loadBalance);
         Assertions.assertNotEquals(o1, o3);
     }