Merge remote-tracking branch 'benpeart/fscache-per-thread-gfw'

This brings substantial wins in performance because the FSCache is now
per-thread, being merged to the primary thread only at the end, so we do
not have to lock (except while merging).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

builtin/add.c

@@ -475,7 +475,7 @@ int cmd_add(int argc,
 	die_in_unpopulated_submodule(repo->index, prefix);
 	die_path_inside_submodule(repo->index, &pathspec);
 
-	enable_fscache(1);
+	enable_fscache(0);
 	/* We do not really re-read the index but update the up-to-date flags */
 	preload_index(repo->index, &pathspec, 0);
 

builtin/checkout.c

@@ -405,7 +405,7 @@ static int checkout_worktree(const struct checkout_opts *opts,
 	if (pc_workers > 1)
 		init_parallel_checkout();
 
-	enable_fscache(1);
+	enable_fscache(the_repository->index->cache_nr);
 	for (pos = 0; pos < the_repository->index->cache_nr; pos++) {
 		struct cache_entry *ce = the_repository->index->cache[pos];
 		if (ce->ce_flags & CE_MATCHED) {
@@ -431,7 +431,7 @@ static int checkout_worktree(const struct checkout_opts *opts,
 		errs |= run_parallel_checkout(&state, pc_workers, pc_threshold,
 					      NULL, NULL);
 	mem_pool_discard(&ce_mem_pool, should_validate_cache_entries());
-	enable_fscache(0);
+	disable_fscache();
 	remove_marked_cache_entries(the_repository->index, 1);
 	remove_scheduled_dirs();
 	errs |= finish_delayed_checkout(&state, opts->show_progress);

builtin/commit.c

@@ -1575,7 +1575,7 @@ struct repository *repo UNUSED)
 		       PATHSPEC_PREFER_FULL,
 		       prefix, argv);
 
-	enable_fscache(1);
+	enable_fscache(0);
 	if (status_format != STATUS_FORMAT_PORCELAIN &&
 	    status_format != STATUS_FORMAT_PORCELAIN_V2)
 		progress_flag = REFRESH_PROGRESS;
@@ -1616,7 +1616,7 @@ struct repository *repo UNUSED)
 	wt_status_print(&s);
 	wt_status_collect_free_buffers(&s);
 
-	enable_fscache(0);
+	disable_fscache();
 	return 0;
 }