Mark Levedahl$git checkout <tab> was taking about 3.5 seconds to respond on one repository having four remotes with about 100 total refs (measured on Cygwin). All of the time was being claimed in "git for-each-ref" to do its work. This working directory was created using git-new-workdir, and thus .git/refs and .git/packed-refs are both symlinks. for-each-ref operates in a way that causes the .git/refs symlink to be resolved multiple times for each ref in the repository, and Cygwin is especially slow in such operations.
Patching refs.c to avoid repeatedly dereferencing the symlink reduced execution time from about 3.5 seconds to about 1.1 seconds (but no improvement on Linux), while an alternate approach of replacing the ref-list expansion with a shell pipeline provides a larger improvement on Cygwin and also improves Linux. So, the shell pipeline approach is provided here.
Relevant timing results using the same repository on both Linux and Cygwin:
On Cygwin:
$ time git for-each-ref --format="%(refname:short)" refs
real 0m3.523s user 0m0.436s sys 0m2.733s
$ time (cd "$GIT_DIR" ; cat packed-refs ; find refs/ -type f) \ 2>/dev/null | sed -ne 's@^.*refs/@refs/@p' | sort | uniq
real 0m0.503s user 0m0.307s sys 0m0.139s
On Linux (essentially the same hardware):
$ time git for-each-ref --format="%(refname:short)" refs
real 0m0.020s user 0m0.006s sys 0m0.014s
$ time (cd "$GIT_DIR" ; cat packed-refs ; find refs/ -type f) \ 2>/dev/null | sed -ne 's@^.*refs/@refs/@p' | sort | uniq
real 0m0.012s user 0m0.006s sys 0m0.005s
So, this is a win even on Linux, but more importantly it makes use of tab completion tolerable on Cygwin when symlinks are involved.
Signed-off-by: Mark Levedahl <mlevedahl@gmail.com> --- contrib/completion/git-completion.bash | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)
Show changes to contrib/completion/git-completion.bash +14 −8
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash index 965778e..62d976e 100644 --- a/contrib/completion/git-completion.bash +++ b/contrib/completion/git-completion.bash @@ -319,8 +319,9 @@ __git_heads () { local dir="$(__gitdir)" if [ -d "$dir" ]; then - git --git-dir="$dir" for-each-ref --format='%(refname:short)' \ - refs/heads + (cd "$dir" ; cat packed-refs ; find refs/heads -type f) 2>/dev/null | + sed -ne 's@^.*refs/heads/@@p' | + sort -u return fi } @@ -329,8 +330,9 @@ __git_tags () { local dir="$(__gitdir)" if [ -d "$dir" ]; then - git --git-dir="$dir" for-each-ref --format='%(refname:short)' \ - refs/tags + (cd "$dir" ; cat packed-refs ; find refs/tags -type f) 2>/dev/null | + sed -ne 's@^.*refs/tags/@@p' | + sort -u return fi } @@ -348,17 +350,21 @@ __git_refs () format="refname" refs="${cur%/*}" track="" + (cd "$dir" ; cat packed-refs ; find refs/ -type f) 2>/dev/null | + sed -ne 's@^.*refs/@refs/@p' | + sort -u + return ;; *) for i in HEAD FETCH_HEAD ORIG_HEAD MERGE_HEAD; do if [ -e "$dir/$i" ]; then echo $i; fi done - format="refname:short" - refs="refs/tags refs/heads refs/remotes" + (cd "$dir" ; cat packed-refs ; find refs/ -type f) 2>/dev/null | + sed -rne 's@^.*refs/(heads|remotes|tags)/@@p' | + sort -u + return ;; esac - git --git-dir="$dir" for-each-ref --format="%($format)" \ - $refs if [ -n "$track" ]; then # employ the heuristic used by git checkout # Try to find a remote branch that matches the completion word
-- 2.1.2.2.0.14
