s/OnServingStatusChange/OnServingStatusUpdate (#26010)

* s/OnServingStatusChange/OnServingStatusUpdate

* Update python files

include/grpc/grpc.h

@@ -414,7 +414,7 @@ GRPCAPI void grpc_server_register_completion_queue(grpc_server* server,
 // There might be more methods added later, so users should take care to memset
 // this to 0 before using it.
 typedef struct {
-  void (*on_serving_status_change)(void* user_data, const char* uri,
+  void (*on_serving_status_update)(void* user_data, const char* uri,
                                    grpc_status_code code,
                                    const char* error_message);
   void* user_data;

include/grpcpp/xds_server_builder.h

@@ -32,9 +32,12 @@ class XdsServerServingStatusNotifierInterface {
 
   // \a uri contains the listening target associated with the notification. Note
   // that a single target provided to XdsServerBuilder can get resolved to
-  // multiple listening addresses. Status::OK signifies that the server is
-  // serving, while a non-OK status signifies that the server is not serving.
-  virtual void OnServingStatusChange(std::string uri, grpc::Status status) = 0;
+  // multiple listening addresses.
+  // The callback is invoked each time there is an update to the serving status.
+  // The API does not provide any guarantees around duplicate updates.
+  // Status::OK signifies that the server is serving, while a non-OK status
+  // signifies that the server is not serving.
+  virtual void OnServingStatusUpdate(std::string uri, grpc::Status status) = 0;
 };
 
 class XdsServerBuilder : public ::grpc::ServerBuilder {
@@ -53,18 +56,18 @@ class XdsServerBuilder : public ::grpc::ServerBuilder {
     ChannelArguments args = ServerBuilder::BuildChannelArgs();
     grpc_channel_args c_channel_args = args.c_channel_args();
     grpc_server_config_fetcher* fetcher = grpc_server_config_fetcher_xds_create(
-        {OnServingStatusChange, notifier_}, &c_channel_args);
+        {OnServingStatusUpdate, notifier_}, &c_channel_args);
     if (fetcher != nullptr) set_fetcher(fetcher);
     return args;
   }
 
-  static void OnServingStatusChange(void* user_data, const char* uri,
+  static void OnServingStatusUpdate(void* user_data, const char* uri,
                                     grpc_status_code code,
                                     const char* error_message) {
     if (user_data == nullptr) return;
     XdsServerServingStatusNotifierInterface* notifier =
         static_cast<XdsServerServingStatusNotifierInterface*>(user_data);
-    notifier->OnServingStatusChange(
+    notifier->OnServingStatusUpdate(
         uri, grpc::Status(static_cast<StatusCode>(code), error_message));
   }
 

src/core/ext/xds/xds_server_config_fetcher.cc

@@ -425,8 +425,8 @@ class XdsServerConfigFetcher : public grpc_server_config_fetcher {
         return;
       }
       if (filter_chain_match_manager_ == nullptr) {
-        if (serving_status_notifier_.on_serving_status_change != nullptr) {
-          serving_status_notifier_.on_serving_status_change(
+        if (serving_status_notifier_.on_serving_status_update != nullptr) {
+          serving_status_notifier_.on_serving_status_update(
               serving_status_notifier_.user_data, listening_address_.c_str(),
               GRPC_STATUS_OK, "");
         } else {
@@ -456,8 +456,8 @@ class XdsServerConfigFetcher : public grpc_server_config_fetcher {
                 this, grpc_error_std_string(error).c_str(),
                 listening_address_.c_str());
       } else {
-        if (serving_status_notifier_.on_serving_status_change != nullptr) {
-          serving_status_notifier_.on_serving_status_change(
+        if (serving_status_notifier_.on_serving_status_update != nullptr) {
+          serving_status_notifier_.on_serving_status_update(
               serving_status_notifier_.user_data, listening_address_.c_str(),
               GRPC_STATUS_UNAVAILABLE, grpc_error_std_string(error).c_str());
         } else {
@@ -483,8 +483,8 @@ class XdsServerConfigFetcher : public grpc_server_config_fetcher {
         server_config_watcher_->StopServing();
         filter_chain_match_manager_.reset();
       }
-      if (serving_status_notifier_.on_serving_status_change != nullptr) {
-        serving_status_notifier_.on_serving_status_change(
+      if (serving_status_notifier_.on_serving_status_update != nullptr) {
+        serving_status_notifier_.on_serving_status_update(
             serving_status_notifier_.user_data, listening_address_.c_str(),
             static_cast<grpc_status_code>(status.raw_code()),
             std::string(status.message()).c_str());

src/python/grpcio/grpc/_cython/_cygrpc/grpc.pxi

@@ -405,7 +405,7 @@ cdef extern from "grpc/grpc.h":
        grpc_server* server, grpc_server_config_fetcher* config_fetcher) nogil
 
   ctypedef struct grpc_server_xds_status_notifier:
-    void (*on_serving_status_change)(void* user_data, const char* uri,
+    void (*on_serving_status_update)(void* user_data, const char* uri,
                                    grpc_status_code code,
                                    const char* error_message)
     void* user_data;

src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi

@@ -26,7 +26,7 @@ cdef class Server:
     cdef _ChannelArgs channel_args = _ChannelArgs(arguments)
     self.c_server = grpc_server_create(channel_args.c_args(), NULL)
     cdef grpc_server_xds_status_notifier notifier
-    notifier.on_serving_status_change = NULL
+    notifier.on_serving_status_update = NULL
     notifier.user_data = NULL
     if xds:
       grpc_server_set_config_fetcher(self.c_server,

test/cpp/end2end/xds_end2end_test.cc

@@ -2264,7 +2264,7 @@ class XdsEnd2endTest : public ::testing::TestWithParam<TestType> {
   class XdsServingStatusNotifier
       : public grpc::experimental::XdsServerServingStatusNotifierInterface {
    public:
-    void OnServingStatusChange(std::string uri, grpc::Status status) override {
+    void OnServingStatusUpdate(std::string uri, grpc::Status status) override {
       grpc_core::MutexLock lock(&mu_);
       status_map[uri] = status;
       cond_.Signal();