config: make `delta_base_cache_limit` a non-global variable

The `delta_base_cache_limit` variable is a global config variable used
by multiple subsystems. Let's make this non-global, by adding this
variable independently to the subsystems where it is used.

First, add the setting to the `repo_settings` struct, this provides
access to the config in places where the repository is available. Use
this in `packfile.c`.

In `index-pack.c` we add it to the `pack_idx_option` struct and its
constructor. While the repository struct is available here, it may not
be set  because `git index-pack` can be used without a repository.

In `gc.c` add it to the `gc_config` struct and also the constructor
function. The gc functions currently do not have direct access to a
repository struct.

These changes are made to remove the usage of `delta_base_cache_limit`
as a global variable in `packfile.c`. This brings us one step closer to
removing the `USE_THE_REPOSITORY_VARIABLE` definition in `packfile.c`
which we complete in the next patch.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 18 insertions, 4 deletions

diff --git a/builtin/gc.c b/builtin/gc.c
index d52735354c..efb6162fb0 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -138,6 +138,11 @@ struct gc_config {
 	char *repack_filter_to;
 	unsigned long big_pack_threshold;
 	unsigned long max_delta_cache_size;
+	/*
+	 * Remove this member from gc_config once repo_settings is passed
+	 * through the callchain.
+	 */
+	size_t delta_base_cache_limit;
 };
 
 #define GC_CONFIG_INIT { \
@@ -153,6 +158,7 @@ struct gc_config {
 	.prune_expire = xstrdup("2.weeks.ago"), \
 	.prune_worktrees_expire = xstrdup("3.months.ago"), \
 	.max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE, \
+	.delta_base_cache_limit = DEFAULT_DELTA_BASE_CACHE_LIMIT, \
 }
 
 static void gc_config_release(struct gc_config *cfg)
@@ -168,6 +174,7 @@ static void gc_config(struct gc_config *cfg)
 {
 	const char *value;
 	char *owned = NULL;
+	unsigned long ulongval;
 
 	if (!git_config_get_value("gc.packrefs", &value)) {
 		if (value && !strcmp(value, "notbare"))
@@ -206,6 +213,9 @@ static void gc_config(struct gc_config *cfg)
 	git_config_get_ulong("gc.bigpackthreshold", &cfg->big_pack_threshold);
 	git_config_get_ulong("pack.deltacachesize", &cfg->max_delta_cache_size);
 
+	if (!git_config_get_ulong("core.deltabasecachelimit", &ulongval))
+		cfg->delta_base_cache_limit = ulongval;
+
 	if (!git_config_get_string("gc.repackfilter", &owned)) {
 		free(cfg->repack_filter);
 		cfg->repack_filter = owned;
@@ -416,7 +426,7 @@ static uint64_t estimate_repack_memory(struct gc_config *cfg,
 	 * read_sha1_file() (either at delta calculation phase, or
 	 * writing phase) also fills up the delta base cache
 	 */
-	heap += delta_base_cache_limit;
+	heap += cfg->delta_base_cache_limit;
 	/* and of course pack-objects has its own delta cache */
 	heap += cfg->max_delta_cache_size;
 
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index eaefb41761..23bfa45403 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1238,7 +1238,7 @@ static void parse_pack_objects(unsigned char *hash)
  *   recursively checking if the resulting object is used as a base
  *   for some more deltas.
  */
-static void resolve_deltas(void)
+static void resolve_deltas(struct pack_idx_option *opts)
 {
 	int i;
 
@@ -1254,7 +1254,7 @@ static void resolve_deltas(void)
 					  nr_ref_deltas + nr_ofs_deltas);
 
 	nr_dispatched = 0;
-	base_cache_limit = delta_base_cache_limit * nr_threads;
+	base_cache_limit = opts->delta_base_cache_limit * nr_threads;
 	if (nr_threads > 1 || getenv("GIT_FORCE_THREADS")) {
 		init_thread();
 		work_lock();
@@ -1604,6 +1604,10 @@ static int git_index_pack_config(const char *k, const char *v,
 		else
 			opts->flags &= ~WRITE_REV;
 	}
+	if (!strcmp(k, "core.deltabasecachelimit")) {
+		opts->delta_base_cache_limit = git_config_ulong(k, v, ctx->kvi);
+		return 0;
+	}
 	return git_default_config(k, v, ctx, cb);
 }
 
@@ -1930,7 +1934,7 @@ int cmd_index_pack(int argc,
 	parse_pack_objects(pack_hash);
 	if (report_end_of_input)
 		write_in_full(2, "\0", 1);
-	resolve_deltas();
+	resolve_deltas(&opts);
 	conclude_pack(fix_thin_pack, curr_pack, pack_hash);
 	free(ofs_deltas);
 	free(ref_deltas);