Send GOAWAY (#233)

HTTP/2 connection sends GOAWAY on error, or during normal shutdown.

Author: graebm

include/aws/http/private/h2_connection.h

@@ -95,6 +95,14 @@ struct aws_h2_connection {
          * Defaults to max stream-id, may be lowered when GOAWAY frame received. */
         uint32_t goaway_received_last_stream_id;
 
+        /* Last-stream-id sent in most recent GOAWAY frame. Defaults to max stream-id. */
+        uint32_t goaway_sent_last_stream_id;
+
+        /* Cached channel shutdown values.
+         * If possible, we delay shutdown-in-the-write-dir until GOAWAY is written. */
+        int channel_shutdown_error_code;
+        bool channel_shutdown_immediately;
+        bool channel_shutdown_waiting_for_goaway_to_be_written;
     } thread_data;
 
     /* Any thread may touch this data, but the lock must be held (unless it's an atomic) */