Re: [PATCH 3/3] clean: improve performance when removing lots of directories
From: Eric Sunshine <hidden>
Date: 2016-06-15 23:04:23
On Mon, Apr 6, 2015 at 7:48 AM, Erik Elfström [off-list ref] wrote:
Before this change, clean used resolve_gitlink_ref to check for the presence of nested git repositories. This had the drawback of creating a ref_cache entry for every directory that should potentially be cleaned. The linear search through the ref_cache list caused a massive performance hit for large number of directories. Teach clean.c:remove_dirs to use setup.c:is_git_directory instead. is_git_directory will actually open HEAD and parse the HEAD ref but this implies a nested git repository and should be rare when cleaning. Using is_git_directory should give a more standardized check for what is and what isn't a git repository but also gives a slight behavioral change. We will now detect and respect bare and empty nested git repositories (only init run). Update t7300 to reflect this. The time to clean an untracked directory containing 100000 sub directories went from 61s to 1.7s after this change.
Impressive.
Signed-off-by: Erik Elfström <redacted> Helped-by: Jeff King [off-list ref]
It is customary for your sign-off to be last. More below...
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---diff --git a/builtin/clean.c b/builtin/clean.c index 98c103f..e951bd9 100644 --- a/builtin/clean.c +++ b/builtin/clean.c@@ -148,6 +147,24 @@ static int exclude_cb(const struct option *opt, const char *arg, int unset) return 0; } +static int is_git_repository(struct strbuf *path) +{ + int ret = 0; + if (is_git_directory(path->buf)) + ret = 1; + else { + int orig_path_len = path->len; + if (path->buf[orig_path_len - 1] != '/')
Minor: I don't know how others feel about it, but I always find it a bit disturbing to see a potential negative array access without a safety check that orig_path_len is not 0, either directly in the conditional or as a documenting assert().
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+ strbuf_addch(path, '/'); + strbuf_addstr(path, ".git"); + if (is_git_directory(path->buf)) + ret = 1; + strbuf_setlen(path, orig_path_len); + } + + return ret; +} + static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag, int dry_run, int quiet, int *dir_gone) {