[PATCH 4/6] fetch: add --refilter option

["Robert Coup via GitGitGadget" <gitgitgadget@gmail.com>]

From: Robert Coup <robert@coup.net.nz>

Teach fetch and transports the --refilter option to force a full fetch
when applying a new filter.

Signed-off-by: Robert Coup <robert@coup.net.nz>
---
 Documentation/fetch-options.txt |  9 +++++++++
 builtin/fetch.c                 | 18 +++++++++++++++++-
 transport-helper.c              |  3 +++
 transport.c                     |  4 ++++
 transport.h                     |  4 ++++
 5 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/Documentation/fetch-options.txt b/Documentation/fetch-options.txt
index e967ff1874c..004078bfea9 100644
--- a/Documentation/fetch-options.txt
+++ b/Documentation/fetch-options.txt
@@ -162,6 +162,15 @@ endif::git-pull[]
 	behavior for a remote may be specified with the remote.<name>.tagOpt
 	setting. See linkgit:git-config[1].
 
+ifndef::git-pull[]
+--refilter::
+	Reapply a partial clone filter from configuration or `--filter=`, such
+	as when the filter definition has changed. Instead of negotiating with
+	the server to avoid transferring commits and associated objects that are
+	already present locally, this option fetches all objects that match the
+	filter.
+endif::git-pull[]
+
 --refmap=<refspec>::
 	When fetching refs listed on the command line, use the
 	specified refspec (can be given more than once) to map the
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 5f06b21f8e9..1dec90fb25f 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -59,7 +59,7 @@ static int prune_tags = -1; /* unspecified */
 
 static int all, append, dry_run, force, keep, multiple, update_head_ok;
 static int write_fetch_head = 1;
-static int verbosity, deepen_relative, set_upstream;
+static int verbosity, deepen_relative, set_upstream, refilter;
 static int progress = -1;
 static int enable_auto_gc = 1;
 static int tags = TAGS_DEFAULT, unshallow, update_shallow, deepen;
@@ -189,6 +189,9 @@ static struct option builtin_fetch_options[] = {
 	OPT_SET_INT_F(0, "unshallow", &unshallow,
 		      N_("convert to a complete repository"),
 		      1, PARSE_OPT_NONEG),
+	OPT_SET_INT_F(0, "refilter", &refilter,
+		      N_("re-fetch with a modified filter"),
+		      1, PARSE_OPT_NONEG),
 	{ OPTION_STRING, 0, "submodule-prefix", &submodule_prefix, N_("dir"),
 		   N_("prepend this to submodule path output"), PARSE_OPT_HIDDEN },
 	OPT_CALLBACK_F(0, "recurse-submodules-default",
@@ -1292,6 +1295,17 @@ static int check_exist_and_connected(struct ref *ref_map)
 	if (deepen)
 		return -1;
 
+	/*
+	 * Similarly, if we need to refilter a partial clone we already have
+	 * these commits reachable.  Running rev-list here will return with
+	 * a good (0) exit status and we'll bypass the fetch that we
+	 * really need to perform.  Claiming failure now will ensure
+	 * we perform the network exchange to reapply the filter.
+	 */
+	if (refilter)
+		return -1;
+
+
 	/*
 	 * check_connected() allows objects to merely be promised, but
 	 * we need all direct targets to exist.
@@ -1487,6 +1501,8 @@ static struct transport *prepare_transport(struct remote *remote, int deepen)
 		set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, "yes");
 	if (update_shallow)
 		set_option(transport, TRANS_OPT_UPDATE_SHALLOW, "yes");
+	if (refilter)
+		set_option(transport, TRANS_OPT_REFILTER, "yes");
 	if (filter_options.choice) {
 		const char *spec =
 			expand_list_objects_filter_spec(&filter_options);
diff --git a/transport-helper.c b/transport-helper.c
index a0297b0986c..3cab1ccc8d5 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -715,6 +715,9 @@ static int fetch_refs(struct transport *transport,
 	if (data->transport_options.update_shallow)
 		set_helper_option(transport, "update-shallow", "true");
 
+	if (data->transport_options.refilter)
+		set_helper_option(transport, "refilter", "true");
+
 	if (data->transport_options.filter_options.choice) {
 		const char *spec = expand_list_objects_filter_spec(
 			&data->transport_options.filter_options);
diff --git a/transport.c b/transport.c
index 2a3e3241545..a150964e20d 100644
--- a/transport.c
+++ b/transport.c
@@ -243,6 +243,9 @@ static int set_git_option(struct git_transport_options *opts,
 		list_objects_filter_die_if_populated(&opts->filter_options);
 		parse_list_objects_filter(&opts->filter_options, value);
 		return 0;
+	} else if (!strcmp(name, TRANS_OPT_REFILTER)) {
+		opts->refilter = !!value;
+		return 0;
 	} else if (!strcmp(name, TRANS_OPT_REJECT_SHALLOW)) {
 		opts->reject_shallow = !!value;
 		return 0;
@@ -377,6 +380,7 @@ static int fetch_refs_via_pack(struct transport *transport,
 	args.update_shallow = data->options.update_shallow;
 	args.from_promisor = data->options.from_promisor;
 	args.filter_options = data->options.filter_options;
+	args.refilter = data->options.refilter;
 	args.stateless_rpc = transport->stateless_rpc;
 	args.server_options = transport->server_options;
 	args.negotiation_tips = data->options.negotiation_tips;
diff --git a/transport.h b/transport.h
index 3f16e50c196..6e21a5b0393 100644
--- a/transport.h
+++ b/transport.h
@@ -16,6 +16,7 @@ struct git_transport_options {
 	unsigned update_shallow : 1;
 	unsigned reject_shallow : 1;
 	unsigned deepen_relative : 1;
+	unsigned refilter : 1;
 
 	/* see documentation of corresponding flag in fetch-pack.h */
 	unsigned from_promisor : 1;
@@ -216,6 +217,9 @@ void transport_check_allowed(const char *type);
 /* Filter objects for partial clone and fetch */
 #define TRANS_OPT_LIST_OBJECTS_FILTER "filter"
 
+/* Refilter a previous partial clone */
+#define TRANS_OPT_REFILTER "refilter"
+
 /* Request atomic (all-or-nothing) updates when pushing */
 #define TRANS_OPT_ATOMIC "atomic"
 
-- 
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