[fix #740] Add more logs in getregionstore (#751)

* optimize getregionstore logical

Signed-off-by: shiyuhang <[email protected]>

* decrease impact

Signed-off-by: shiyuhang <[email protected]>

* Update RegionManager.java

Signed-off-by: shiyuhang <[email protected]>

* [close #749] Fix health checking issue (#748)

Signed-off-by: shiyuhang <[email protected]>

* Update RegionManager.java

Signed-off-by: shiyuhang <[email protected]>

* add log

Signed-off-by: shiyuhang <[email protected]>

* change log level

Signed-off-by: shiyuhang <[email protected]>

---------

Signed-off-by: shiyuhang <[email protected]>

Author: shiyuhang0

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

@@ -177,8 +177,13 @@ public TiRegion getRegionByKey(ByteString key, BackOffer backOffer) {
         Pair<Metapb.Region, Metapb.Peer> regionAndLeader = pdClient.getRegionByKey(backOffer, key);
         region =
             cache.putRegion(createRegion(regionAndLeader.first, regionAndLeader.second, backOffer));
+        logger.debug(
+            String.format(
+                "get region id: %d with leader: %d",
+                region.getId(), region.getLeader().getStoreId()));
       }
     } catch (Exception e) {
+      logger.warn("Get region failed: ", e);
       return null;
     } finally {
       requestTimer.observeDuration();
@@ -240,6 +245,10 @@ public Pair<TiRegion, TiStore> getRegionStorePairByKey(
         }
         logger.info("Store {} is unreachable, try to get the next replica", peer.getStoreId());
       }
+      // Does not set unreachable store to null in case it is incompatible with GrpcForward
+      if (store == null || !store.isReachable()) {
+        logger.warn("No TiKV store available for region: " + region);
+      }
     } else {
       List<TiStore> tiflashStores = new ArrayList<>();
       for (Peer peer : region.getLearnerList()) {