completion: let 'for-each-ref' and 'ls-remote' filter matching refs

When completing refs, several __git_refs() code paths list all the
refs from the refs/{heads,tags,remotes}/ hierarchy and then
__gitcomp_nl() iterates over those refs in a shell loop to filter out
refs not matching the current ref to be completed.  This comes with a
considerable performance penalty when a repository contains a lot of
refs but the current ref can be uniquely completed or when only a
handful of refs match the current ref.

Reduce the number of iterations in __gitcomp_nl() from the number of
refs to the number of matching refs by specifying appropriate globbing
patterns to 'git for-each-ref' and 'git ls-remote' to list only those
refs that match the current ref to be completed.  However, do so only
when the ref to match is explicitly given as parameter, because the
current word on the command line might contain a prefix like
'--option=' or 'branch..'.  The __git_complete_refs() and
__git_complete_fetch_refspecs() helpers introduced previously in this
patch series already call __git_refs() specifying this current ref
parameter, so all their callsites, i.e. all places in the completion
script doing refs completion, can benefit from this optimization.

Furthermore, list only those symbolic and pseudo refs that match the
current ref to be completed.  Though it doesn't matter at all in
itself performance-wise, it will allow us further significant
optimizations later in this series.

This speeds up refs completion considerably when there are a lot of
non-matching refs to be filtered out.  Uniquely completing a branch in
a repository with 100k local branches, all packed, best of five:

  On Linux, before:

    $ time __git_complete_refs --cur=maste

    real    0m0.831s
    user    0m0.808s
    sys     0m0.028s

  After:

    real    0m0.119s
    user    0m0.104s
    sys     0m0.008s

  On Windows, before:

    real    0m1.480s
    user    0m1.031s
    sys     0m0.060s

  After:

    real    0m0.377s
    user    0m0.015s
    sys     0m0.030s

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 5ee35d530ed799867b1200bcc7c07e8cca3e4d33..976f8059885cf8f95e440486c01ff92d8425fe68 100644 (file)
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -355,7 +355,8 @@ __git_tags ()
 # 2: In addition to local refs, list unique branches from refs/remotes/ for
 #    'git checkout's tracking DWIMery (optional; ignored, if set but empty).
 # 3: Currently ignored.
-# 4: The current ref to be completed (optional).
+# 4: List only refs matching this word (optional; list all refs if unset or
+#    empty).
 #
 # Use __git_complete_refs() instead.
 __git_refs ()
@@ -364,6 +365,7 @@ __git_refs ()
        local list_refs_from=path remote="${1-}"
        local format refs pfx
        local cur_="${4-$cur}"
+       local match="${4-}"
 
        __git_find_repo_path
        dir="$__git_repo_path"
@@ -390,23 +392,32 @@ __git_refs ()
                if [[ "$cur_" == ^* ]]; then
                        pfx="^"
                        cur_=${cur_#^}
+                       match=${match#^}
                fi
                case "$cur_" in
                refs|refs/*)
                        format="refname"
-                       refs="${cur_%/*}"
+                       refs=("$match*" "$match*/**")
                        track=""
                        ;;
                *)
                        for i in HEAD FETCH_HEAD ORIG_HEAD MERGE_HEAD; do
-                               if [ -e "$dir/$i" ]; then echo $pfx$i; fi
+                               case "$i" in
+                               $match*)
+                                       if [ -e "$dir/$i" ]; then
+                                               echo $pfx$i
+                                       fi
+                                       ;;
+                               esac
                        done
                        format="refname:strip=2"
-                       refs="refs/tags refs/heads refs/remotes"
+                       refs=("refs/tags/$match*" "refs/tags/$match*/**"
+                               "refs/heads/$match*" "refs/heads/$match*/**"
+                               "refs/remotes/$match*" "refs/remotes/$match*/**")
                        ;;
                esac
                __git_dir="$dir" __git for-each-ref --format="$pfx%($format)" \
-                       $refs
+                       "${refs[@]}"
                if [ -n "$track" ]; then
                        # employ the heuristic used by git checkout
                        # Try to find a remote branch that matches the completion word
@@ -417,7 +428,7 @@ __git_refs ()
                        while read -r entry; do
                                eval "$entry"
                                ref="${ref#*/}"
-                               if [[ "$ref" == "$cur_"* ]]; then
+                               if [[ "$ref" == "$match"* ]]; then
                                        echo "$ref"
                                fi
                        done | sort | uniq -u
@@ -426,7 +437,7 @@ __git_refs ()
        fi
        case "$cur_" in
        refs|refs/*)
-               __git ls-remote "$remote" "$cur_*" | \
+               __git ls-remote "$remote" "$match*" | \
                while read -r hash i; do
                        case "$i" in
                        *^{}) ;;
@@ -436,12 +447,20 @@ __git_refs ()
                ;;
        *)
                if [ "$list_refs_from" = remote ]; then
-                       echo "HEAD"
+                       case "HEAD" in
+                       $match*)        echo "HEAD" ;;
+                       esac
                        __git for-each-ref --format="%(refname:strip=2)" \
-                               "refs/remotes/$remote/" | sed -e "s#^$remote/##"
+                               "refs/remotes/$remote/$match*" \
+                               "refs/remotes/$remote/$match*/**" | sed -e "s#^$remote/##"
                else
-                       __git ls-remote "$remote" HEAD \
-                               "refs/tags/*" "refs/heads/*" "refs/remotes/*" |
+                       local query_symref
+                       case "HEAD" in
+                       $match*)        query_symref="HEAD" ;;
+                       esac
+                       __git ls-remote "$remote" $query_symref \
+                               "refs/tags/$match*" "refs/heads/$match*" \
+                               "refs/remotes/$match*" |
                        while read -r hash i; do
                                case "$i" in
                                *^{})   ;;

diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index e2b45f62519c7929ad3b3ba99c60a618f36f4693..cc9e741f929784582c418d25e919fd39ad426bfa 100755 (executable)
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -555,6 +555,9 @@ test_expect_success '__git_refs - full refs' '
        cat >expected <<-EOF &&
        refs/heads/master
        refs/heads/matching-branch
+       refs/remotes/other/branch-in-other
+       refs/remotes/other/master-in-other
+       refs/tags/matching-tag
        EOF
        (
                cur=refs/heads/ &&
@@ -620,6 +623,7 @@ test_expect_success '__git_refs - configured remote' '
 
 test_expect_success '__git_refs - configured remote - full refs' '
        cat >expected <<-EOF &&
+       HEAD
        refs/heads/branch-in-other
        refs/heads/master-in-other
        refs/tags/tag-in-other
@@ -648,6 +652,7 @@ test_expect_success '__git_refs - configured remote - repo given on the command
 
 test_expect_success '__git_refs - configured remote - full refs - repo given on the command line' '
        cat >expected <<-EOF &&
+       HEAD
        refs/heads/branch-in-other
        refs/heads/master-in-other
        refs/tags/tag-in-other
@@ -692,6 +697,7 @@ test_expect_success '__git_refs - URL remote' '
 
 test_expect_success '__git_refs - URL remote - full refs' '
        cat >expected <<-EOF &&
+       HEAD
        refs/heads/branch-in-other
        refs/heads/master-in-other
        refs/tags/tag-in-other
@@ -837,6 +843,124 @@ test_expect_success '__git refs - exluding full refs' '
        test_cmp expected "$actual"
 '
 
+test_expect_success 'setup for filtering matching refs' '
+       git branch matching/branch &&
+       git tag matching/tag &&
+       git -C otherrepo branch matching/branch-in-other &&
+       git fetch --no-tags other &&
+       rm -f .git/FETCH_HEAD
+'
+
+test_expect_success '__git_refs - dont filter refs unless told so' '
+       cat >expected <<-EOF &&
+       HEAD
+       master
+       matching-branch
+       matching/branch
+       other/branch-in-other
+       other/master-in-other
+       other/matching/branch-in-other
+       matching-tag
+       matching/tag
+       EOF
+       (
+               cur=master &&
+               __git_refs >"$actual"
+       ) &&
+       test_cmp expected "$actual"
+'
+
+test_expect_success '__git_refs - only matching refs' '
+       cat >expected <<-EOF &&
+       matching-branch
+       matching/branch
+       matching-tag
+       matching/tag
+       EOF
+       (
+               cur=mat &&
+               __git_refs "" "" "" "$cur" >"$actual"
+       ) &&
+       test_cmp expected "$actual"
+'
+
+test_expect_success '__git_refs - only matching refs - full refs' '
+       cat >expected <<-EOF &&
+       refs/heads/matching-branch
+       refs/heads/matching/branch
+       EOF
+       (
+               cur=refs/heads/mat &&
+               __git_refs "" "" "" "$cur" >"$actual"
+       ) &&
+       test_cmp expected "$actual"
+'
+
+test_expect_success '__git_refs - only matching refs - remote on local file system' '
+       cat >expected <<-EOF &&
+       master-in-other
+       matching/branch-in-other
+       EOF
+       (
+               cur=ma &&
+               __git_refs otherrepo "" "" "$cur" >"$actual"
+       ) &&
+       test_cmp expected "$actual"
+'
+
+test_expect_success '__git_refs - only matching refs - configured remote' '
+       cat >expected <<-EOF &&
+       master-in-other
+       matching/branch-in-other
+       EOF
+       (
+               cur=ma &&
+               __git_refs other "" "" "$cur" >"$actual"
+       ) &&
+       test_cmp expected "$actual"
+'
+
+test_expect_success '__git_refs - only matching refs - remote - full refs' '
+       cat >expected <<-EOF &&
+       refs/heads/master-in-other
+       refs/heads/matching/branch-in-other
+       EOF
+       (
+               cur=refs/heads/ma &&
+               __git_refs other "" "" "$cur" >"$actual"
+       ) &&
+       test_cmp expected "$actual"
+'
+
+test_expect_success '__git_refs - only matching refs - checkout DWIMery' '
+       cat >expected <<-EOF &&
+       matching-branch
+       matching/branch
+       matching-tag
+       matching/tag
+       matching/branch-in-other
+       EOF
+       for remote_ref in refs/remotes/other/ambiguous \
+               refs/remotes/remote/ambiguous \
+               refs/remotes/remote/branch-in-remote
+       do
+               git update-ref $remote_ref master &&
+               test_when_finished "git update-ref -d $remote_ref"
+       done &&
+       (
+               cur=mat &&
+               __git_refs "" 1 "" "$cur" >"$actual"
+       ) &&
+       test_cmp expected "$actual"
+'
+
+test_expect_success 'teardown after filtering matching refs' '
+       git branch -d matching/branch &&
+       git tag -d matching/tag &&
+       git update-ref -d refs/remotes/other/matching/branch-in-other &&
+       git -C otherrepo branch -D matching/branch-in-other
+'
+
 test_expect_success '__git_complete_refs - simple' '
        sed -e "s/Z$//" >expected <<-EOF &&
        HEAD Z