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| author | Cristian Staretu <unclejacksons@gmail.com> | 2014-07-03 09:40:53 +1000 |
|---|---|---|
| committer | Cristian Staretu <unclejacksons@gmail.com> | 2014-07-03 09:40:53 +1000 |
| commit | f60fd68eb4104eebce10df35ebeae552c7b21261 (patch) | |
| tree | c6f36646ffe55b74287c0dd9e6d66b566fdbb982 | |
| parent | e56bbe646461f2bc55ce2b086c7d5accd001efb1 (diff) | |
| download | go-f60fd68eb4104eebce10df35ebeae552c7b21261.tar.gz | |
archive/tar: reuse temporary buffer in writeHeader
A temporary 512 bytes buffer is allocated for every call to
writeHeader. This buffer could be reused the lower the number
of memory allocations.
benchmark old ns/op new ns/op delta
BenchmarkWriteFiles100k 634622051 583810847 -8.01%
benchmark old allocs new allocs delta
BenchmarkWriteFiles100k 2701920 2602621 -3.68%
benchmark old bytes new bytes delta
BenchmarkWriteFiles100k 115383884 64349922 -44.23%
This change is very important if your code has to write a lot of
tarballs with a lot of files.
LGTM=dsymonds
R=golang-codereviews, dave, dsymonds
CC=golang-codereviews
https://codereview.appspot.com/107440043
Committer: David Symonds <dsymonds@golang.org>
| -rw-r--r-- | src/pkg/archive/tar/writer.go | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/src/pkg/archive/tar/writer.go b/src/pkg/archive/tar/writer.go index 6eff6f6f8..d107dbbb5 100644 --- a/src/pkg/archive/tar/writer.go +++ b/src/pkg/archive/tar/writer.go @@ -37,8 +37,9 @@ type Writer struct { nb int64 // number of unwritten bytes for current file entry pad int64 // amount of padding to write after current file entry closed bool - usedBinary bool // whether the binary numeric field extension was used - preferPax bool // use pax header instead of binary numeric header + usedBinary bool // whether the binary numeric field extension was used + preferPax bool // use pax header instead of binary numeric header + hdrBuff [blockSize]byte // buffer to use in writeHeader } // NewWriter creates a new Writer writing to w. @@ -160,7 +161,8 @@ func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error { // subsecond time resolution, but for now let's just capture // too long fields or non ascii characters - header := make([]byte, blockSize) + header := tw.hdrBuff[:] + copy(header, zeroBlock) s := slicer(header) // keep a reference to the filename to allow to overwrite it later if we detect that we can use ustar longnames instead of pax |