Merge pull request #7918 from y-zeng/server_builder

Add ServerBuilderPlugin::UpdateChannelArguments

include/grpc++/impl/server_builder_plugin.h

@@ -41,6 +41,7 @@
 namespace grpc {
 
 class ServerInitializer;
+class ChannelArguments;
 
 class ServerBuilderPlugin {
  public:
@@ -58,6 +59,10 @@ class ServerBuilderPlugin {
   // ServerBuilderOption::UpdatePlugins
   virtual void ChangeArguments(const grpc::string& name, void* value) = 0;
 
+  // UpdateChannelArguments will be called in ServerBuilder::BuildAndStart(),
+  // before the Server instance is created.
+  virtual void UpdateChannelArguments(ChannelArguments* args) {}
+
   virtual bool has_sync_methods() const { return false; }
   virtual bool has_async_methods() const { return false; }
 };

src/cpp/server/server_builder.cc

@@ -153,14 +153,12 @@ std::unique_ptr<Server> ServerBuilder::BuildAndStart() {
     (*option)->UpdateArguments(&args);
     (*option)->UpdatePlugins(&plugins_);
   }
-  if (!thread_pool) {
-    for (auto plugin = plugins_.begin(); plugin != plugins_.end(); plugin++) {
-      if ((*plugin)->has_sync_methods()) {
-        thread_pool.reset(CreateDefaultThreadPool());
-        has_sync_methods = true;
-        break;
-      }
+  for (auto plugin = plugins_.begin(); plugin != plugins_.end(); plugin++) {
+    if (!thread_pool && (*plugin)->has_sync_methods()) {
+      thread_pool.reset(CreateDefaultThreadPool());
+      has_sync_methods = true;
     }
+    (*plugin)->UpdateChannelArguments(&args);
   }
   if (max_message_size_ > 0) {
     args.SetInt(GRPC_ARG_MAX_MESSAGE_LENGTH, max_message_size_);