fix pair equality check (tikv#724)

Signed-off-by: shiyuhang <1136742008@qq.com>

Author: shiyuhang0

src/main/java/org/tikv/common/util/Pair.java

@@ -18,6 +18,7 @@
 package org.tikv.common.util;
 
 import java.io.Serializable;
+import java.util.Objects;
 
 public class Pair<F, S> implements Serializable {
   public final F first;
@@ -36,4 +37,21 @@ public static <F, S> Pair<F, S> create(F f, S s) {
   public String toString() {
     return String.format("[%s:%s]", first, second);
   }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    Pair<?, ?> pair = (Pair<?, ?>) o;
+    return Objects.equals(first, pair.first) && Objects.equals(second, pair.second);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(first, second);
+  }
 }

src/test/java/org/tikv/common/util/PairTest.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2023 TiKV Project Authors.
+ *
+ * Licensed 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.tikv.common.util;
+
+import com.google.common.collect.ImmutableList;
+import com.google.protobuf.ByteString;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import org.junit.Test;
+import org.tikv.common.PDMockServerTest;
+import org.tikv.common.region.TiRegion;
+import org.tikv.common.region.TiStore;
+import org.tikv.kvproto.Metapb;
+import org.tikv.kvproto.Metapb.Peer;
+
+public class PairTest extends PDMockServerTest {
+
+  @Test
+  public void testPair() {
+    Metapb.Region r =
+        Metapb.Region.newBuilder()
+            .setRegionEpoch(Metapb.RegionEpoch.newBuilder().setConfVer(1).setVersion(2))
+            .setId(233)
+            .setStartKey(ByteString.EMPTY)
+            .setEndKey(ByteString.EMPTY)
+            .addPeers(Peer.getDefaultInstance())
+            .build();
+    List<Metapb.Store> s =
+        ImmutableList.of(
+            Metapb.Store.newBuilder()
+                .setAddress(LOCAL_ADDR + ":" + 4000)
+                .setVersion("5.0.0")
+                .setId(1)
+                .build());
+
+    TiRegion region =
+        new TiRegion(
+            session.getConf(),
+            r,
+            r.getPeers(0),
+            r.getPeersList(),
+            s.stream().map(TiStore::new).collect(Collectors.toList()));
+    TiStore store = new TiStore(s.get(0));
+
+    Map<Pair<TiRegion, TiStore>, List<ByteString>> groupKeyMap = new HashMap<>();
+
+    for (int i = 0; i < 10; i++) {
+      Pair<TiRegion, TiStore> pair = Pair.create(region, store);
+      groupKeyMap
+          .computeIfAbsent(pair, e -> new ArrayList<>())
+          .add(ByteString.copyFromUtf8("test"));
+    }
+    Pair<TiRegion, TiStore> pair = Pair.create(region, store);
+    assert (groupKeyMap.get(pair).size() == 10);
+  }
+}