!9135 Minor fixs for cache error message

From: @tina_mengting_zhang
Reviewed-by: @mikef,@robingrosman
Signed-off-by: @nsyca

mindspore/ccsrc/minddata/dataset/engine/cache/cache_client.cc

@@ -217,7 +217,7 @@ Status CacheClient::CreateCache(uint32_t tree_crc, bool generate_id) {
   // That is allowed, however the crc better match!
   if (server_connection_id_) {
     if (cinfo_.crc() != tree_crc) {
-      RETURN_STATUS_UNEXPECTED("Attempt to re-use a cache for a different tree!");
+      RETURN_STATUS_UNEXPECTED("Cannot re-use a cache for a different tree!");
     }
     // Check the state of the server. For non-mappable case where there is a build phase and a fetch phase, we should
     // skip the build phase.

mindspore/ccsrc/minddata/dataset/engine/cache/cache_grpc_client.cc

@@ -20,7 +20,7 @@ namespace dataset {
 CacheClientGreeter::~CacheClientGreeter() { (void)ServiceStop(); }
 
 CacheClientGreeter::CacheClientGreeter(const std::string &hostname, int32_t port, int32_t num_connections)
-    : num_connections_(num_connections), request_cnt_(0) {
+    : num_connections_(num_connections), request_cnt_(0), port_(port) {
   grpc::ChannelArguments args;
   // We need to bump up the message size to unlimited. The default receiving
   // message limit is 4MB which is not big enough.
@@ -119,8 +119,8 @@ Status CacheClientGreeter::WorkerEntry() {
           auto error_code = rq->rc_.error_code();
           std::string err_msg;
           if (error_code == grpc::StatusCode::UNAVAILABLE) {
-            err_msg =
-              "Cache server is unreachable. Make sure the server is running.  GRPC Code" + std::to_string(error_code);
+            err_msg = "Cache server with port " + std::to_string(port_) +
+                      " is unreachable. Make sure the server is running.  GRPC Code" + std::to_string(error_code);
           } else {
             err_msg = rq->rc_.error_message() + ". GRPC Code " + std::to_string(error_code);
           }

mindspore/ccsrc/minddata/dataset/engine/cache/cache_grpc_client.h

@@ -96,6 +96,7 @@ class CacheClientGreeter : public Service {
   mutable std::mutex mux_;
   std::map<int64_t, std::unique_ptr<CacheClientRequestTag>> req_;
   SharedMemory mem_;
+  int32_t port_;
 };
 }  // namespace dataset
 }  // namespace mindspore

tests/ut/python/dataset/test_cache_nomap.py

@@ -590,7 +590,7 @@ def test_cache_nomap_disallowed_share1():
 
     with pytest.raises(RuntimeError) as e:
         sum([1 for _ in ds2])
-    assert "Attempt to re-use a cache for a different tree!" in str(e.value)
+    assert "Cannot re-use a cache for a different tree!" in str(e.value)
 
     logger.info("test_cache_nomap_disallowed_share1 Ended.\n")
 
@@ -1182,7 +1182,8 @@ def test_cache_nomap_server_stop():
         num_iter = 0
         for _ in ds1.create_dict_iterator():
             num_iter += 1
-    assert "Network error. Cache server is unreachable. Make sure the server is running." in str(e.value)
+    assert "Network error. Cache server with port 50052 is unreachable. Make sure the server is running." in \
+           str(e.value)
 
     logger.info("test_cache_nomap_server_stop Ended.\n")