2 files changed, 13 insertions, 0 deletions
diff --git a/reftable/reftable-writer.h b/reftable/reftable-writer.h
index c85ef5a5bd..5f9afa620b 100644
--- a/reftable/reftable-writer.h
+++ b/reftable/reftable-writer.h
@@ -68,6 +68,15 @@ struct reftable_write_options {
 	 * fsync(3P) when unset.
 	 */
 	int (*fsync)(int fd);
+
+	/*
+	 * Callback function to execute whenever the stack is being reloaded.
+	 * This can be used e.g. to discard cached information that relies on
+	 * the old stack's data. The payload data will be passed as argument to
+	 * the callback.
+	 */
+	void (*on_reload)(void *payload);
+	void *on_reload_payload;
 };
 
 /* reftable_block_stats holds statistics for a single block type */
diff --git a/reftable/stack.c b/reftable/stack.c
index 8beb5c0541..59fd695a12 100644
--- a/reftable/stack.c
+++ b/reftable/stack.c
@@ -548,6 +548,10 @@ out:
 		close(fd);
 	free_names(names);
 	free_names(names_after);
+
+	if (st->opts.on_reload)
+		st->opts.on_reload(st->opts.on_reload_payload);
+
 	return err;
 }