proxy: rework backend buffer handling

experimental change. *io_uring mode is presently broken*

there are some potential protocol desync bugs due to mcmc handling its
own buffers and the newer event handler handling its own syscalls.

this change should have better separation of code for the buffer
tracking. if this change works I will add some optimizations to reduce
memmove's.

1 files changed, 2 insertions, 1 deletions

diff --git a/proxy.h b/proxy.h
index 1c44ef3..4d88867 100644
--- a/proxy.h
+++ b/proxy.h
@@ -310,7 +310,8 @@ struct mcp_backend_s {
     void *client; // mcmc client
     STAILQ_ENTRY(mcp_backend_s) be_next; // stack for backends
     io_head_t io_head; // stack of requests.
-    char *rbuf; // static allocated read buffer.
+    char *rbuf; // statically allocated read buffer.
+    size_t rbufused; // currently active bytes in the buffer
     struct event event; // libevent
 #ifdef HAVE_LIBURING
     proxy_event_t ur_rd_ev; // liburing.