Improve cluster slots slotNodes using arrays (redis#3373)

* Performance improvement cluster slots slotNodes cache switch hashmap to arrays

Signed-off-by: c00603587 <chenshi35@huawei.com>
Co-authored-by: c00603587 <chenshi35@huawei.com>

src/main/java/redis/clients/jedis/JedisClusterInfoCache.java

@@ -1,6 +1,7 @@
 package redis.clients.jedis;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -21,8 +22,8 @@
 public class JedisClusterInfoCache {
 
   private final Map<String, ConnectionPool> nodes = new HashMap<>();
-  private final Map<Integer, ConnectionPool> slots = new HashMap<>();
-  private final Map<Integer, HostAndPort> slotNodes = new HashMap<>();
+  private final ConnectionPool[] slots = new ConnectionPool[Protocol.CLUSTER_HASHSLOTS];
+  private final HostAndPort[] slotNodes = new HostAndPort[Protocol.CLUSTER_HASHSLOTS];
 
   private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
   private final Lock r = rwl.readLock();
@@ -148,8 +149,8 @@ private void discoverClusterSlots(Connection jedis) {
     }
     w.lock();
     try {
-      this.slots.clear();
-      this.slotNodes.clear();
+      Arrays.fill(slots, null);
+      Arrays.fill(slotNodes, null);
       Set<String> hostAndPortKeys = new HashSet<>();
 
       for (Object slotInfoObj : slotsInfo) {
@@ -224,8 +225,8 @@ public void assignSlotToNode(int slot, HostAndPort targetNode) {
     w.lock();
     try {
       ConnectionPool targetPool = setupNodeIfNotExist(targetNode);
-      slots.put(slot, targetPool);
-      slotNodes.put(slot, targetNode);
+      slots[slot] = targetPool;
+      slotNodes[slot] = targetNode;
     } finally {
       w.unlock();
     }
@@ -236,8 +237,8 @@ public void assignSlotsToNode(List<Integer> targetSlots, HostAndPort targetNode)
     try {
       ConnectionPool targetPool = setupNodeIfNotExist(targetNode);
       for (Integer slot : targetSlots) {
-        slots.put(slot, targetPool);
-        slotNodes.put(slot, targetNode);
+        slots[slot] = targetPool;
+        slotNodes[slot] = targetNode;
       }
     } finally {
       w.unlock();
@@ -260,7 +261,7 @@ public ConnectionPool getNode(HostAndPort node) {
   public ConnectionPool getSlotPool(int slot) {
     r.lock();
     try {
-      return slots.get(slot);
+      return slots[slot];
     } finally {
       r.unlock();
     }
@@ -269,7 +270,7 @@ public ConnectionPool getSlotPool(int slot) {
   public HostAndPort getSlotNode(int slot) {
     r.lock();
     try {
-      return slotNodes.get(slot);
+      return slotNodes[slot];
     } finally {
       r.unlock();
     }
@@ -311,8 +312,8 @@ public void reset() {
         }
       }
       nodes.clear();
-      slots.clear();
-      slotNodes.clear();
+      Arrays.fill(slots, null);
+      Arrays.fill(slotNodes, null);
     } finally {
       w.unlock();
     }