Re: [PATCH v2 6/7] promisor-remote: lazy-fetch objects in subprocess

Jonathan Tan [off-list ref] writes:

Teach Git to lazy-fetch missing objects in a subprocess instead of doing
it in-process. This allows any fatal errors that occur during the fetch
to be isolated and converted into an error return value, instead of
causing the current command being run to terminate.

...
 static int fetch_objects(const char *remote_name,
 			 const struct object_id *oids,
 			 int oid_nr)
 {
-	struct ref *ref = NULL;
+	struct child_process child = CHILD_PROCESS_INIT;
 	int i;
+	FILE *child_in;
+
+	child.git_cmd = 1;
+	child.in = -1;
+	argv_array_pushl(&child.args, "-c", "fetch.negotiationAlgorithm=null",
+			 "fetch", remote_name, "--no-tags",
+			 "--no-write-fetch-head", "--recurse-submodules=no",
+			 "--filter=blob:none", "--stdin", NULL);

Finally we get to use the new negotiator introduced earlier.  Nice.

+	if (start_command(&child))
+		die(_("promisor-remote: unable to fork off fetch subprocess"));
+	child_in = xfdopen(child.in, "w");