[close #736] Select reachable store (#737)

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

pom.xml

@@ -3,7 +3,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>org.tikv</groupId>
     <artifactId>tikv-client-java</artifactId>
-    <version>3.3.0-SNAPSHOT</version>
+    <version>3.3.4-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>TiKV Java Client</name>
     <description>A Java Client for TiKV</description>

src/main/java/org/tikv/common/region/RegionManager.java

@@ -228,12 +228,25 @@ public class RegionManager {
 
     TiStore store = null;
     if (storeType == TiStoreType.TiKV) {
-      Peer peer = region.getCurrentReplica();
-      store = getStoreById(peer.getStoreId(), backOffer);
+      // check from the first replica in case it recovers
+      List<Peer> replicaList = region.getReplicaList();
+      for (int i = 0; i < replicaList.size(); i++) {
+        Peer peer = replicaList.get(i);
+        store = getStoreById(peer.getStoreId(), backOffer);
+        if (store.isReachable()) {
+          // update replica's index
+          region.setReplicaIdx(i);
+          break;
+        }
+        logger.info("Store {} is unreachable, try to get the next replica", peer.getStoreId());
+      }
     } else {
       List<TiStore> tiflashStores = new ArrayList<>();
       for (Peer peer : region.getLearnerList()) {
         TiStore s = getStoreById(peer.getStoreId(), backOffer);
+        if (!s.isReachable()) {
+          continue;
+        }
         for (Metapb.StoreLabel label : s.getStore().getLabelsList()) {
           if (label.getKey().equals(storeType.getLabelKey())
               && label.getValue().equals(storeType.getLabelValue())) {

src/main/java/org/tikv/common/region/TiRegion.java

@@ -126,6 +126,14 @@ public class TiRegion implements Serializable {
     return getCurrentReplica();
   }
 
+  public void setReplicaIdx(int idx) {
+    replicaIdx = idx;
+  }
+
+  public List<Peer> getReplicaList() {
+    return replicaList;
+  }
+
   private boolean isLeader(Peer peer) {
     return getLeader().equals(peer);
   }