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authorDavid Symonds <dsymonds@golang.org>2018-06-21 13:24:03 +1000
committerDavid Symonds <dsymonds@golang.org>2018-06-21 13:31:25 +1000
commit2d9816a5e7daea58a1419fef70bfc8d220ffd6a2 (patch)
treed1578365030c0179b221f43517929b551b0c5840 /plumbing/format
parent0710c6cb710a0cdab04ab7f61cc62e23cfcacbee (diff)
downloadgo-git-2d9816a5e7daea58a1419fef70bfc8d220ffd6a2.tar.gz
packfile: optimise NewIndexFromIdxFile for a very common case
Loading from an on-disk idxfile will usually already have the idxfile entries in order, so check that before wasting time on sorting. Signed-off-by: David Symonds <dsymonds@golang.org>
Diffstat (limited to 'plumbing/format')
-rw-r--r--plumbing/format/packfile/index.go14
1 files changed, 12 insertions, 2 deletions
diff --git a/plumbing/format/packfile/index.go b/plumbing/format/packfile/index.go
index 7d8f2ad..021b2d1 100644
--- a/plumbing/format/packfile/index.go
+++ b/plumbing/format/packfile/index.go
@@ -31,10 +31,20 @@ func NewIndexFromIdxFile(idxf *idxfile.Idxfile) *Index {
byHash: make(map[plumbing.Hash]*idxfile.Entry, idxf.ObjectCount),
byOffset: make([]*idxfile.Entry, 0, idxf.ObjectCount),
}
- for _, e := range idxf.Entries {
+ sorted := true
+ for i, e := range idxf.Entries {
idx.addUnsorted(e)
+ if i > 0 && idx.byOffset[i-1].Offset >= e.Offset {
+ sorted = false
+ }
+ }
+
+ // If the idxfile was loaded from a regular packfile index
+ // then it will already be in offset order, in which case we
+ // can avoid doing a relatively expensive idempotent sort.
+ if !sorted {
+ sort.Sort(orderByOffset(idx.byOffset))
}
- sort.Sort(orderByOffset(idx.byOffset))
return idx
}