maintenance: care about gvfs.sharedCache config

For Scalar and VFS for Git, we use an alternate as a shared object cache. We need to enable the maintenance builtin to work on that shared object cache, especially in the background. 'scalar run <task>' would set GIT_OBJECT_DIRECTORY to handle this. We set GIT_OBJECT_DIRECTORY based on the gvfs.sharedCache config, but we also need the checks in pack_loose() to look at that object directory instead of the current ODB's. Signed-off-by: Derrick Stolee <dstolee@microsoft.com>

Author: derrickstolee

builtin/gc.c

@@ -999,18 +999,23 @@ static int write_loose_object_to_stdin(const struct object_id *oid,
 return ++(d->count) > d->batch_size;
 }
 
+static const char *object_dir = NULL;
+
 static int pack_loose(struct maintenance_run_opts *opts)
 {
 struct repository *r = the_repository;
 int result = 0;
 struct write_loose_object_data data;
 struct child_process pack_proc = CHILD_PROCESS_INIT;
 
+if (!object_dir)
+object_dir = r->objects->odb->path;
+
 /*
  * Do not start pack-objects process
  * if there are no loose objects.
  */
-if (!for_each_loose_file_in_objdir(r->objects->odb->path,
+if (!for_each_loose_file_in_objdir(object_dir,
  bail_on_loose,
  NULL, NULL, NULL))
 return 0;
@@ -1020,7 +1025,7 @@ static int pack_loose(struct maintenance_run_opts *opts)
 strvec_push(&pack_proc.args, "pack-objects");
 if (opts->quiet)
 strvec_push(&pack_proc.args, "--quiet");
-strvec_pushf(&pack_proc.args, "%s/pack/loose", r->objects->odb->path);
+strvec_pushf(&pack_proc.args, "%s/pack/loose", object_dir);
 
 pack_proc.in = -1;
 
@@ -1033,7 +1038,7 @@ static int pack_loose(struct maintenance_run_opts *opts)
 data.count = 0;
 data.batch_size = 50000;
 
-for_each_loose_file_in_objdir(r->objects->odb->path,
+for_each_loose_file_in_objdir(object_dir,
  write_loose_object_to_stdin,
  NULL,
  NULL,
@@ -1441,6 +1446,16 @@ static int maintenance_run(int argc, const char **argv, const char *prefix)
 if (argc != 0)
 usage_with_options(builtin_maintenance_run_usage,
  builtin_maintenance_run_options);
+
+/*
+ * To enable the VFS for Git/Scalar shared object cache, use
+ * the gvfs.sharedcache config option to redirect the
+ * maintenance to that location.
+ */
+if (!git_config_get_value("gvfs.sharedcache", &object_dir) &&
+ object_dir)
+setenv(DB_ENVIRONMENT, object_dir, 1);
+
 return maintenance_run_tasks(&opts);
 }