implement shutdown request handling in endpoints

src/tateyama/endpoint/common/worker_common.h

@@ -249,6 +249,35 @@ class worker_common {
             return true;
         }
 
+        case tateyama::proto::endpoint::request::Request::kShutdown:
+        {
+            VLOG_LP(log_trace) << "received shutdown request, slot = " << slot;  //NOLINT
+            {
+                tateyama::session::shutdown_request_type shutdown_type{};
+                switch (rq.shutdown().type()) {
+                case tateyama::proto::endpoint::request::ShutdownType::SHUTDOWN_TYPE_NOT_SET:
+                    shutdown_type = tateyama::session::shutdown_request_type::forceful;
+                    break;
+                case tateyama::proto::endpoint::request::ShutdownType::GRACEFUL:
+                    shutdown_type = tateyama::session::shutdown_request_type::graceful;
+                    break;
+                case tateyama::proto::endpoint::request::ShutdownType::FORCEFUL:
+                    shutdown_type = tateyama::session::shutdown_request_type::forceful;
+                    break;
+                default: // error
+                    return false;
+                }
+                request_shutdown(shutdown_type);
+
+                // FIXME confirm when response should be sent
+                tateyama::proto::endpoint::response::Shutdown rp{};
+                auto body = rp.SerializeAsString();
+                res->body(body);
+                return true;
+            }
+            return true;
+        }
+
         default: // error
         {
             std::stringstream ss;

src/tateyama/proto/endpoint/request.proto

@@ -24,8 +24,11 @@ message Request {
 
         // cancel operation.
         Cancel cancel = 12;
+
+        // shutdown operation.
+        Shutdown shutdown = 13;
     }
-    reserved 13 to 99;
+    reserved 14 to 99;
 }
 
 // handshake operation.
@@ -81,3 +84,23 @@ message WireInformation {
 message Cancel {
     // no special properties.
 }
+
+// kind of shutdown type.
+enum ShutdownType {
+
+    // The default shutdown type.
+    SHUTDOWN_TYPE_NOT_SET = 0;
+
+    // Waits for the ongoing requests and safely shutdown the session.
+    GRACEFUL = 1;
+
+    // Cancelling the ongoing requests and safely shutdown the session.
+    FORCEFUL = 2;
+}
+
+// request shutdown to the session.
+message Shutdown {
+
+    // the shutdown type.
+    ShutdownType type = 1;
+}

src/tateyama/proto/endpoint/response.proto

@@ -39,3 +39,8 @@ message Handshake {
         uint64 session_id = 11;
     }
 }
+
+// shutdown operation.
+message Shutdown {
+    // no special message
+}