msgpack-rpc: Refactor API metadata discovery method

A new method is now exposed via msgpack-rpc: "get_api_metadata". This method has
the same job as the old method '0', it returns an object with API metadata for
use by generators.

There's one difference in the return value though: instead of returning a
string containing another serialized msgpack document, the metadata object is
returned directly(a separate deserialization step by clients is not required).

1 files changed, 14 insertions, 32 deletions

diff --git a/src/nvim/os/msgpack_rpc.c b/src/nvim/os/msgpack_rpc.c
index 4a586e8e01..b06c8ee597 100644
--- a/src/nvim/os/msgpack_rpc.c
+++ b/src/nvim/os/msgpack_rpc.c
@@ -17,8 +17,7 @@
 # include "os/msgpack_rpc.c.generated.h"
 #endif
 
-extern const uint8_t msgpack_metadata[];
-extern const unsigned int msgpack_metadata_size;
+extern msgpack_unpacked msgpack_unpacked_metadata;
 
 /// Validates the basic structure of the msgpack-rpc call and fills `res`
 /// with the basic response structure.
@@ -39,11 +38,6 @@ WBuffer *msgpack_rpc_call(uint64_t channel_id,
     return serialize_response(response_id, err, NIL, sbuffer);
   }
 
-  if (req->via.array.ptr[2].type == MSGPACK_OBJECT_POSITIVE_INTEGER
-     && req->via.array.ptr[2].via.u64 == 0) {
-    return serialize_metadata(response_id, channel_id, sbuffer);
-  }
-
   // dispatch the call
   Error error = { .set = false };
   Object rv = msgpack_rpc_dispatch(channel_id, req, &error);
@@ -125,6 +119,19 @@ Object msgpack_rpc_handle_missing_method(uint64_t channel_id,
   return NIL;
 }
 
+/// Handler for retrieving API metadata through a msgpack-rpc call
+Object msgpack_rpc_handle_get_api_metadata(uint64_t channel_id,
+                                           msgpack_object *req,
+                                           Error *error)
+{
+  Array rv = ARRAY_DICT_INIT;
+  Object metadata;
+  msgpack_rpc_to_object(&msgpack_unpacked_metadata.data, &metadata);
+  ADD(rv, INTEGER_OBJ((int64_t)channel_id));
+  ADD(rv, metadata);
+  return ARRAY_OBJ(rv);
+}
+
 /// Serializes a msgpack-rpc request or notification(id == 0)
 WBuffer *serialize_request(uint64_t request_id,
                            String method,
@@ -190,31 +197,6 @@ WBuffer *serialize_response(uint64_t response_id,
   return rv;
 }
 
-WBuffer *serialize_metadata(uint64_t id,
-                            uint64_t channel_id,
-                            msgpack_sbuffer *sbuffer)
-  FUNC_ATTR_NONNULL_ALL
-{
-  msgpack_packer pac;
-  msgpack_packer_init(&pac, sbuffer, msgpack_sbuffer_write);
-  msgpack_pack_array(&pac, 4);
-  msgpack_pack_int(&pac, 1);
-  msgpack_pack_uint64(&pac, id);
-  // Nil error
-  msgpack_pack_nil(&pac);
-  // The result is the [channel_id, metadata] array
-  msgpack_pack_array(&pac, 2);
-  msgpack_pack_uint64(&pac, channel_id);
-  msgpack_pack_bin(&pac, msgpack_metadata_size);
-  msgpack_pack_bin_body(&pac, msgpack_metadata, msgpack_metadata_size);
-  WBuffer *rv = wstream_new_buffer(xmemdup(sbuffer->data, sbuffer->size),
-                                   sbuffer->size,
-                                   1,
-                                   free);
-  msgpack_sbuffer_clear(sbuffer);
-  return rv;
-}
-
 static char *msgpack_rpc_validate(uint64_t *response_id, msgpack_object *req)
 {
   // response id not known yet