Robust status overriding

src/core/surface/call.c

@@ -89,6 +89,19 @@ typedef struct reqinfo {
   gpr_uint32 complete_mask;
 } reqinfo;
 
+typedef enum {
+  STATUS_FROM_API_OVERRIDE = 0,
+  STATUS_FROM_WIRE,
+  STATUS_FROM_FAILED_OP,
+  STATUS_SOURCE_COUNT
+} status_source;
+
+typedef struct {
+  gpr_uint8 set;
+  grpc_status_code code;
+  grpc_mdstr *details;
+} received_status;
+
 struct grpc_call {
   grpc_completion_queue *cq;
   grpc_channel *channel;
@@ -113,8 +126,7 @@ struct grpc_call {
   grpc_metadata_array buffered_trailing_metadata;
   size_t write_index;
 
-  grpc_status_code status_code;
-  grpc_mdstr *status_details;
+  received_status status[STATUS_SOURCE_COUNT];
 
   grpc_alarm alarm;
 
@@ -176,11 +188,14 @@ void grpc_call_internal_ref(grpc_call *c) {
 }
 
 static void destroy_call(grpc_call *c) {
+  int i;
   grpc_call_stack_destroy(CALL_STACK_FROM_CALL(c));
   grpc_channel_internal_unref(c->channel);
   gpr_mu_destroy(&c->mu);
-  if (c->status_details) {
-    grpc_mdstr_unref(c->status_details);
+  for (i = 0; i < STATUS_SOURCE_COUNT; i++) {
+    if (c->status[i].details) {
+      grpc_mdstr_unref(c->status[i].details);
+    }
   }
   if (c->legacy_state) {
     gpr_free(c->legacy_state->md_out);
@@ -198,6 +213,18 @@ void grpc_call_internal_unref(grpc_call *c) {
   }
 }
 
+static void set_status_code(grpc_call *call, status_source source, gpr_uint32 status) {
+  call->status[source].set = 1;
+  call->status[source].code = status;
+}
+
+static void set_status_details(grpc_call *call, status_source source, grpc_mdstr *status) {
+  if (call->status[source].details != NULL) {
+    grpc_mdstr_unref(call->status[source].details);
+  }
+  call->status[source].details = status;
+}
+
 static grpc_call_error bind_cq(grpc_call *call, grpc_completion_queue *cq) {
   if (call->cq) return GRPC_CALL_ERROR_ALREADY_INVOKED;
   call->cq = cq;
@@ -258,6 +285,19 @@ static void unlock(grpc_call *call) {
   }
 }
 
+static void get_final_status(grpc_call *call, grpc_status_code *code, const char **details) {
+  int i;
+  for (i = 0; i < STATUS_SOURCE_COUNT; i++) {
+    if (call->status[i].set) {
+      *code = call->status[i].code;
+      *details = grpc_mdstr_as_c_string(call->status[i].details);
+      return;
+    }
+  }
+  *code = GRPC_STATUS_UNKNOWN;
+  *details = NULL;
+}
+
 static void finish_ioreq_op(grpc_call *call, grpc_ioreq_op op,
                             grpc_op_error status) {
   reqinfo *master = call->requests[op].master;
@@ -277,12 +317,9 @@ static void finish_ioreq_op(grpc_call *call, grpc_ioreq_op op,
       if (master->complete_mask == master->need_mask ||
           status == GRPC_OP_ERROR) {
         if (OP_IN_MASK(GRPC_IOREQ_RECV_STATUS, master->need_mask)) {
-          call->requests[GRPC_IOREQ_RECV_STATUS].data.recv_status->status =
-              call->status_code;
-          call->requests[GRPC_IOREQ_RECV_STATUS].data.recv_status->details =
-              call->status_details
-                  ? grpc_mdstr_as_c_string(call->status_details)
-                  : NULL;
+          get_final_status(call, 
+          &call->requests[GRPC_IOREQ_RECV_STATUS].data.recv_status->status,
+          &call->requests[GRPC_IOREQ_RECV_STATUS].data.recv_status->details);
         }
         for (i = 0; i < GRPC_IOREQ_OP_COUNT; i++) {
           if (call->requests[i].master == master) {
@@ -600,20 +637,6 @@ void grpc_call_destroy(grpc_call *c) {
   grpc_call_internal_unref(c);
 }
 
-static void maybe_set_status_code(grpc_call *call, gpr_uint32 status) {
-  if (call->got_status_code) return;
-  call->status_code = status;
-  call->got_status_code = 1;
-}
-
-static void maybe_set_status_details(grpc_call *call, grpc_mdstr *status) {
-  if (call->status_details != NULL) {
-    grpc_mdstr_unref(status);
-    return;
-  }
-  call->status_details = status;
-}
-
 grpc_call_error grpc_call_cancel(grpc_call *c) {
   grpc_call_element *elem;
   grpc_call_op op;
@@ -637,10 +660,8 @@ grpc_call_error grpc_call_cancel_with_status(grpc_call *c,
       description ? grpc_mdstr_from_string(c->metadata_context, description)
                   : NULL;
   lock(c);
-  maybe_set_status_code(c, status);
-  if (details) {
-    maybe_set_status_details(c, details);
-  }
+  set_status_code(c, STATUS_FROM_API_OVERRIDE, status);
+  set_status_details(c, STATUS_FROM_API_OVERRIDE, details);
   unlock(c);
   return grpc_call_cancel(c);
 }
@@ -1024,10 +1045,10 @@ void grpc_call_recv_metadata(grpc_call_element *elem, grpc_mdelem *md) {
 
   lock(call);
   if (key == grpc_channel_get_status_string(call->channel)) {
-    maybe_set_status_code(call, decode_status(md));
+    set_status_code(call, STATUS_FROM_WIRE, decode_status(md));
     grpc_mdelem_unref(md);
   } else if (key == grpc_channel_get_message_string(call->channel)) {
-    maybe_set_status_details(call, grpc_mdstr_ref(md->value));
+    set_status_details(call, STATUS_FROM_WIRE, grpc_mdstr_ref(md->value));
     grpc_mdelem_unref(md);
   } else {
     if (!call->got_initial_metadata) {