1 files changed, 27 insertions, 3 deletions

diff --git a/src/core/lib/surface/server.c b/src/core/lib/surface/server.c
index 080734e9d5..55e5e49e11 100644
--- a/src/core/lib/surface/server.c
+++ b/src/core/lib/surface/server.c
@@ -100,6 +100,7 @@ typedef struct requested_call {
 
 typedef struct channel_registered_method {
   registered_method *server_registered_method;
+  uint32_t flags;
   grpc_mdstr *method;
   grpc_mdstr *host;
 } channel_registered_method;
@@ -152,6 +153,7 @@ struct call_data {
   grpc_completion_queue *cq_new;
 
   grpc_metadata_batch *recv_initial_metadata;
+  bool recv_idempotent_request;
   grpc_metadata_array initial_metadata;
 
   grpc_closure got_initial_metadata;
@@ -171,6 +173,7 @@ struct request_matcher {
 struct registered_method {
   char *method;
   char *host;
+  uint32_t flags;
   request_matcher request_matcher;
   registered_method *next;
 };
@@ -468,6 +471,9 @@ static void start_new_rpc(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
       if (!rm) break;
       if (rm->host != calld->host) continue;
       if (rm->method != calld->path) continue;
+      if ((rm->flags & GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST) &&
+          !calld->recv_idempotent_request)
+        continue;
       finish_start_new_rpc(exec_ctx, server, elem,
                            &rm->server_registered_method->request_matcher);
       return;
@@ -480,6 +486,9 @@ static void start_new_rpc(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
       if (!rm) break;
       if (rm->host != NULL) continue;
       if (rm->method != calld->path) continue;
+      if ((rm->flags & GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST) &&
+          !calld->recv_idempotent_request)
+        continue;
       finish_start_new_rpc(exec_ctx, server, elem,
                            &rm->server_registered_method->request_matcher);
       return;
@@ -598,9 +607,11 @@ static void server_mutate_op(grpc_call_element *elem,
   call_data *calld = elem->call_data;
 
   if (op->recv_initial_metadata != NULL) {
+    GPR_ASSERT(op->recv_idempotent_request == NULL);
     calld->recv_initial_metadata = op->recv_initial_metadata;
     calld->on_done_recv_initial_metadata = op->recv_initial_metadata_ready;
     op->recv_initial_metadata_ready = &calld->server_on_recv_initial_metadata;
+    op->recv_idempotent_request = &calld->recv_idempotent_request;
   }
 }
 
@@ -830,10 +841,12 @@ static int streq(const char *a, const char *b) {
 }
 
 void *grpc_server_register_method(grpc_server *server, const char *method,
-                                  const char *host) {
+                                  const char *host, uint32_t flags) {
   registered_method *m;
-  GRPC_API_TRACE("grpc_server_register_method(server=%p, method=%s, host=%s)",
-                 3, (server, method, host));
+  GRPC_API_TRACE(
+      "grpc_server_register_method(server=%p, method=%s, host=%s, "
+      "flags=0x%08x)",
+      4, (server, method, host, flags));
   if (!method) {
     gpr_log(GPR_ERROR,
             "grpc_server_register_method method string cannot be NULL");
@@ -846,12 +859,18 @@ void *grpc_server_register_method(grpc_server *server, const char *method,
       return NULL;
     }
   }
+  if ((flags & ~GRPC_INITIAL_METADATA_USED_MASK) != 0) {
+    gpr_log(GPR_ERROR, "grpc_server_register_method invalid flags 0x%08x",
+            flags);
+    return NULL;
+  }
   m = gpr_malloc(sizeof(registered_method));
   memset(m, 0, sizeof(*m));
   request_matcher_init(&m->request_matcher, server->max_requested_calls);
   m->method = gpr_strdup(method);
   m->host = gpr_strdup(host);
   m->next = server->registered_methods;
+  m->flags = flags;
   server->registered_methods = m;
   return m;
 }
@@ -930,6 +949,7 @@ void grpc_server_setup_transport(grpc_exec_ctx *exec_ctx, grpc_server *s,
       if (probes > max_probes) max_probes = probes;
       crm = &chand->registered_methods[(hash + probes) % slots];
       crm->server_registered_method = rm;
+      crm->flags = rm->flags;
       crm->host = host;
       crm->method = method;
     }
@@ -1247,6 +1267,10 @@ static void begin_call(grpc_exec_ctx *exec_ctx, grpc_server *server,
       cpstr(&rc->data.batch.details->method,
             &rc->data.batch.details->method_capacity, calld->path);
       rc->data.batch.details->deadline = calld->deadline;
+      rc->data.batch.details->flags =
+          0 | (calld->recv_idempotent_request
+                   ? GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST
+                   : 0);
       break;
     case REGISTERED_CALL:
       *rc->data.registered.deadline = calld->deadline;