[close #663] Select TiFlash Stores Round-Robin (#662)

.github/workflows/license-checker.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Check License Header
-        uses: apache/skywalking-eyes@main
+        uses: apache/skywalking-eyes@v0.3.0
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:

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

@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.tikv.common.ReadOnlyPDClient;
@@ -68,6 +69,7 @@ public class RegionManager {
   private final TiConfiguration conf;
   private final ScheduledExecutorService executor;
   private final StoreHealthyChecker storeChecker;
+  private AtomicInteger tiflashStoreIndex = new AtomicInteger(0);
 
   public RegionManager(
       TiConfiguration conf, ReadOnlyPDClient pdClient, ChannelFactory channelFactory) {
@@ -191,17 +193,21 @@ public class RegionManager {
       Peer peer = region.getCurrentReplica();
       store = getStoreById(peer.getStoreId(), backOffer);
     } else {
-      outerLoop:
+      List<TiStore> tiflashStores = new ArrayList<>();
       for (Peer peer : region.getLearnerList()) {
         TiStore s = getStoreById(peer.getStoreId(), backOffer);
         for (Metapb.StoreLabel label : s.getStore().getLabelsList()) {
           if (label.getKey().equals(storeType.getLabelKey())
               && label.getValue().equals(storeType.getLabelValue())) {
-            store = s;
-            break outerLoop;
+            tiflashStores.add(s);
           }
         }
       }
+      // select a tiflash with RR strategy
+      if (tiflashStores.size() > 0) {
+        store = tiflashStores.get(tiflashStoreIndex.getAndIncrement() % tiflashStores.size());
+      }
+
       if (store == null) {
         // clear the region cache, so we may get the learner peer next time
         cache.invalidateRegion(region);

src/test/java/org/tikv/common/GrpcUtils.java

@@ -24,6 +24,7 @@ import java.util.Arrays;
 import org.tikv.common.codec.Codec.BytesCodec;
 import org.tikv.common.codec.CodecDataOutput;
 import org.tikv.kvproto.Metapb.Peer;
+import org.tikv.kvproto.Metapb.PeerRole;
 import org.tikv.kvproto.Metapb.Region;
 import org.tikv.kvproto.Metapb.RegionEpoch;
 import org.tikv.kvproto.Metapb.Store;
@@ -61,6 +62,10 @@ public class GrpcUtils {
     return Peer.newBuilder().setStoreId(storeId).setId(id).build();
   }
 
+  public static Peer makeLearnerPeer(long id, long storeId) {
+    return Peer.newBuilder().setRole(PeerRole.Learner).setStoreId(storeId).setId(id).build();
+  }
+
   public static ByteString encodeKey(byte[] key) {
     CodecDataOutput cdo = new CodecDataOutput();
     BytesCodec.writeBytes(cdo, key);

src/test/java/org/tikv/common/RegionManagerTest.java

@@ -31,6 +31,7 @@ import org.tikv.common.key.Key;
 import org.tikv.common.region.RegionManager;
 import org.tikv.common.region.TiRegion;
 import org.tikv.common.region.TiStore;
+import org.tikv.common.region.TiStoreType;
 import org.tikv.common.util.KeyRangeUtils;
 import org.tikv.common.util.Pair;
 import org.tikv.kvproto.Metapb;
@@ -135,7 +136,7 @@ public class RegionManagerTest extends PDMockServerTest {
 
     Pair<TiRegion, TiStore> pair = mgr.getRegionStorePairByKey(searchKey);
     assertEquals(pair.first.getId(), regionId);
-    assertEquals(pair.first.getId(), storeId);
+    assertEquals(pair.second.getId(), 10);
   }
 
   @Test
@@ -179,4 +180,52 @@ public class RegionManagerTest extends PDMockServerTest {
     } catch (Exception ignored) {
     }
   }
+
+  @Test
+  public void getRegionStorePairByKeyWithTiFlash() {
+
+    ByteString startKey = ByteString.copyFrom(new byte[] {1});
+    ByteString endKey = ByteString.copyFrom(new byte[] {10});
+    ByteString searchKey = ByteString.copyFrom(new byte[] {5});
+    String testAddress = "testAddress";
+    long firstStoreId = 233;
+    long secondStoreId = 234;
+    int confVer = 1026;
+    int ver = 1027;
+    long regionId = 233;
+    leader.addGetRegionListener(
+        request ->
+            GrpcUtils.makeGetRegionResponse(
+                leader.getClusterId(),
+                GrpcUtils.makeRegion(
+                    regionId,
+                    GrpcUtils.encodeKey(startKey.toByteArray()),
+                    GrpcUtils.encodeKey(endKey.toByteArray()),
+                    GrpcUtils.makeRegionEpoch(confVer, ver),
+                    GrpcUtils.makeLearnerPeer(1, firstStoreId),
+                    GrpcUtils.makeLearnerPeer(2, secondStoreId))));
+
+    AtomicInteger i = new AtomicInteger(0);
+    long[] ids = new long[] {firstStoreId, secondStoreId};
+    leader.addGetStoreListener(
+        (request ->
+            GrpcUtils.makeGetStoreResponse(
+                leader.getClusterId(),
+                GrpcUtils.makeStore(
+                    ids[i.getAndIncrement()],
+                    testAddress,
+                    StoreState.Up,
+                    GrpcUtils.makeStoreLabel("engine", "tiflash"),
+                    GrpcUtils.makeStoreLabel("k1", "v1"),
+                    GrpcUtils.makeStoreLabel("k2", "v2")))));
+
+    Pair<TiRegion, TiStore> pair = mgr.getRegionStorePairByKey(searchKey, TiStoreType.TiFlash);
+    assertEquals(pair.first.getId(), regionId);
+    assertEquals(pair.second.getId(), firstStoreId);
+
+    Pair<TiRegion, TiStore> secondPair =
+        mgr.getRegionStorePairByKey(searchKey, TiStoreType.TiFlash);
+    assertEquals(secondPair.first.getId(), regionId);
+    assertEquals(secondPair.second.getId(), secondStoreId);
+  }
 }