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os: reduce allocations in Readdir on unix

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Include syscall.Stat_t on unix to the
unexported fileStat structure rather than
accessing it though an interface.

Additionally add a benchmark for Readdir
(and Readdirnames).

Tested on linux, freebsd, netbsd, openbsd
darwin, solaris, does not touch windows
stuff. Does not change the API, as
discussed on golang-dev.

E.g. on linux/amd64 with a directory of 65 files:

benchmark              old ns/op     new ns/op     delta
BenchmarkReaddir-4     67774         66225         -2.29%

benchmark              old allocs     new allocs     delta
BenchmarkReaddir-4     334            269            -19.46%

benchmark              old bytes     new bytes     delta
BenchmarkReaddir-4     25208         24168         -4.13%

Change-Id: I44ef72a04ad7055523a980f29aa11122040ae8fe
Reviewed-on: https://go-review.googlesource.com/16423
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Taru Karttunen 2015-10-28 12:58:58 +02:00 • committed by Brad Fitzpatrick
parent a21b4bca0c
commit f5f480e1df
12 changed files with 158 additions and 166 deletions
Download patch file Download diff file Expand all files Collapse all files

25
src/os/file_unix.go
View file

@ -12,6 +12,10 @@ import (
"syscall"
)
func sameFile(fs1, fs2 *fileStat) bool {
return fs1.sys.Dev == fs2.sys.Dev && fs1.sys.Ino == fs2.sys.Ino
}
func rename(oldname, newname string) error {
e := syscall.Rename(oldname, newname)
if e != nil {
@ -152,23 +156,25 @@ func (f *File) Stat() (FileInfo, error) {
if f == nil {
return nil, ErrInvalid
}
var stat syscall.Stat_t
err := syscall.Fstat(f.fd, &stat)
var fs fileStat
err := syscall.Fstat(f.fd, &fs.sys)
if err != nil {
return nil, &PathError{"stat", f.name, err}
}
return fileInfoFromStat(&stat, f.name), nil
fillFileStatFromSys(&fs, f.name)
return &fs, nil
}
// Stat returns a FileInfo describing the named file.
// If there is an error, it will be of type *PathError.
func Stat(name string) (FileInfo, error) {
var stat syscall.Stat_t
err := syscall.Stat(name, &stat)
var fs fileStat
err := syscall.Stat(name, &fs.sys)
if err != nil {
return nil, &PathError{"stat", name, err}
}
return fileInfoFromStat(&stat, name), nil
fillFileStatFromSys(&fs, name)
return &fs, nil
}
// Lstat returns a FileInfo describing the named file.
@ -176,12 +182,13 @@ func Stat(name string) (FileInfo, error) {
// describes the symbolic link. Lstat makes no attempt to follow the link.
// If there is an error, it will be of type *PathError.
func Lstat(name string) (FileInfo, error) {
var stat syscall.Stat_t
err := syscall.Lstat(name, &stat)
var fs fileStat
err := syscall.Lstat(name, &fs.sys)
if err != nil {
return nil, &PathError{"lstat", name, err}
}
return fileInfoFromStat(&stat, name), nil
fillFileStatFromSys(&fs, name)
return &fs, nil
}
func (f *File) readdir(n int) (fi []FileInfo, err error) {