From 2d9816a5e7daea58a1419fef70bfc8d220ffd6a2 Mon Sep 17 00:00:00 2001 From: David Symonds Date: Thu, 21 Jun 2018 13:24:03 +1000 Subject: 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 --- plumbing/format/packfile/index.go | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'plumbing/format/packfile') 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 } -- cgit