add handle operation toward rpc err in scan_inner

fix: #493

Author: BryceCao

src/raw/client.rs

@@ -31,6 +31,7 @@ use crate::Key;
 use crate::KvPair;
 use crate::Result;
 use crate::Value;
+use crate::request::plan::is_grpc_error;
 
 const MAX_RAW_KV_SCAN_LIMIT: u32 = 10240;
 
@@ -835,6 +836,17 @@ impl<PdC: PdClient> Client<PdC> {
                     }
                     Ok((Some(r), region.end_key()))
                 }
+                Err(err) if is_grpc_error(&err) => {
+                    debug!("retryable_scan: grpc error: {:?}", err);
+                    plan::invalidate_cache(self.rpc.clone(), store.clone()).await;
+
+                    if let Some(duration) = scan_args.backoff.next_delay_duration() {
+                        sleep(duration).await;
+                        continue;
+                    } else {
+                        return Err(err);
+                    }
+                }
                 Err(err) => Err(err),
             };
         }

src/request/plan.rs

@@ -87,7 +87,7 @@ impl<Req: KvRequest + StoreRequest> StoreRequest for Dispatch<Req> {
 const MULTI_REGION_CONCURRENCY: usize = 16;
 const MULTI_STORES_CONCURRENCY: usize = 16;
 
-fn is_grpc_error(e: &Error) -> bool {
+pub(crate) fn is_grpc_error(e: &Error) -> bool {
     matches!(e, Error::GrpcAPI(_) | Error::Grpc(_))
 }
 
@@ -344,6 +344,18 @@ pub(crate) async fn handle_region_error<PdC: PdClient>(
     }
 }
 
+pub(crate) async fn invalidate_cache<PdC: PdClient>(
+    pd_client: Arc<PdC>,
+    region_store: RegionStore,
+) {
+    let ver_id = region_store.region_with_leader.ver_id();
+    let store_id = region_store.region_with_leader.get_store_id();
+    pd_client.invalidate_region_cache(ver_id).await;
+    if let Ok(store_id) = store_id {
+        pd_client.invalidate_store_cache(store_id).await;
+    }
+}
+
 // Returns
 // 1. Ok(true): error has been resolved, retry immediately
 // 2. Ok(false): backoff, and then retry