refactor(msgpack): allow flushing buffer while packing msgpack

Before, we needed to always pack an entire msgpack_rpc Object to
a continous memory buffer before sending it out to a channel.
But this is generally wasteful. it is better to just flush
whatever is in the buffer and then continue packing to a new buffer.

This is also done for the UI event packer where there are some extra logic
to "finish" of an existing batch of nevents/ncalls. This doesn't really
stop us from flushing the buffer, just that we need to update the state
machine accordingly so the next call to prepare_call() always will
start with a new event (even though the buffer might contain overflow
data from a large event).

1 files changed, 8 insertions, 0 deletions

diff --git a/src/nvim/api/private/defs.h b/src/nvim/api/private/defs.h
index 0cdc90e50f..ca088d7a55 100644
--- a/src/nvim/api/private/defs.h
+++ b/src/nvim/api/private/defs.h
@@ -105,6 +105,14 @@ typedef enum {
   kObjectTypeTabpage,
 } ObjectType;
 
+/// Value by which objects represented as EXT type are shifted
+///
+/// Subtracted when packing, added when unpacking. Used to allow moving
+/// buffer/window/tabpage block inside ObjectType enum. This block yet cannot be
+/// split or reordered.
+#define EXT_OBJECT_TYPE_SHIFT kObjectTypeBuffer
+#define EXT_OBJECT_TYPE_MAX (kObjectTypeTabpage - EXT_OBJECT_TYPE_SHIFT)
+
 struct object {
   ObjectType type;
   union {