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;
 }