When queueing dnd data to send to the client keep space available in the queue so that inut events are not dropped while the dnd is in progress

kitty/child-monitor.c

@@ -370,17 +370,18 @@ static const unsigned write_buf_limit = 100 * 1024 * 1024;
     children_mutex(unlock);
 
 void
-schedule_write_to_child_if_possible(id_type id, const char *data, size_t sz, bool *found, bool *too_much_data) {
+schedule_write_to_child_if_possible(id_type id, const char *data, size_t sz, bool *found, bool *too_much_data, size_t keep_space) {
     children_mutex(lock);
     ChildMonitor *self = the_monitor;
     *found = false; *too_much_data = false;
+    size_t limit = write_buf_limit > keep_space ? write_buf_limit - keep_space : 0;
     for (size_t i = 0; i < self->count; i++) {
         if (children[i].id == id) {
             Screen *screen = children[i].screen;
             screen_mutex(lock, write);
             size_t space_left = screen->write_buf_sz - screen->write_buf_used;
             if (space_left < sz) {
-                if (screen->write_buf_used + sz > write_buf_limit) {
+                if (screen->write_buf_used + sz > limit) {
                     *too_much_data = true;
                     screen_mutex(unlock, write);
                     break;

kitty/data-types.h

@@ -315,7 +315,7 @@ const char* cursor_as_sgr(const Cursor *);
 PyObject* cm_thread_write(PyObject *self, PyObject *args);
 bool schedule_write_to_child(id_type id, unsigned int num, ...);
 bool schedule_write_to_child_python(id_type id, const char *prefix, PyObject* tuple_of_str_or_bytes, const char *suffix);
-void schedule_write_to_child_if_possible(id_type id, const char *data, size_t sz, bool *found, bool *too_much_data);
+void schedule_write_to_child_if_possible(id_type id, const char *data, size_t sz, bool *found, bool *too_much_data, size_t keep_space);
 bool set_iutf8(int, bool);
 
 DynamicColor colorprofile_to_color(const ColorProfile *self, DynamicColor entry, DynamicColor defval);

kitty/dnd.c

@@ -236,6 +236,8 @@ test_write_chunk(id_type id, const char *buf, size_t sz) {
     return true;
 }
 
+static const size_t keep_write_to_child_queue_space = 32 * 1024;
+
 static size_t
 send_payload_to_child(id_type id, uint32_t client_id, const char *header, size_t header_sz, const char *data, const size_t data_sz, bool as_base64) {
     size_t offset = 0;
@@ -246,7 +248,7 @@ send_payload_to_child(id_type id, uint32_t client_id, const char *header, size_t
         buf[header_sz++] = 0x1b; buf[header_sz++] = '\\';
         if (!test_write_chunk(id, buf, header_sz)) {
             bool found, too_much_data;
-            schedule_write_to_child_if_possible(id, buf, header_sz, &found, &too_much_data);
+            schedule_write_to_child_if_possible(id, buf, header_sz, &found, &too_much_data, keep_write_to_child_queue_space);
             if (too_much_data) return 0;
         }
         return 1;
@@ -270,7 +272,7 @@ send_payload_to_child(id_type id, uint32_t client_id, const char *header, size_t
         buf[p++] = 0x1b; buf[p++] = '\\';
         if (!test_write_chunk(id, buf, p)) {
             bool found, too_much_data;
-            schedule_write_to_child_if_possible(id, buf, p, &found, &too_much_data);
+            schedule_write_to_child_if_possible(id, buf, p, &found, &too_much_data, keep_write_to_child_queue_space);
             if (too_much_data) break;
             if (!found) return data_sz;
         }