From 854349eeb45d89c32ccf9fdbce8b857bc4064cd7 Mon Sep 17 00:00:00 2001 From: qmuntal Date: Tue, 13 Aug 2024 15:08:32 +0200 Subject: [PATCH] os/user: speed up Current on Windows MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit [This is a roll-forward of CL 597255, which had to be rolled back because it broke the windows-arm64 builder, whose current user display name is unavailable. This new CL fixes the issue by reintroducing the historical behavior of falling back to the user name instead of returning an error]. user.Current is slow on Windows sessions connected to an Active Directory domain. This is because it uses Windows APIs that do RPC calls to the domain controller, such as TranslateAccountW and NetUserGetInfo. This change speeds up user.Current by using the GetUserNameEx API instead, which is already optimized for retrieving the current user name in different formats. These are the improvements I see with the new implementation: goos: windows goarch: amd64 pkg: os/user cpu: Intel(R) Core(TM) i7-10850H CPU @ 2.70GHz │ old.txt │ new.txt │ │ sec/op │ sec/op vs base │ Current-12 501.8µ ± 7% 118.6µ ± 11% -76.36% (p=0.000 n=10) │ old.txt │ new.txt │ │ B/op │ B/op vs base │ Current-12 888.0 ± 0% 832.0 ± 0% -6.31% (p=0.000 n=10) │ old.txt │ new.txt │ │ allocs/op │ allocs/op vs base │ Current-12 15.00 ± 0% 11.00 ± 0% -26.67% (p=0.000 n=10) Updates #5298 Fixes #21867 Fixes #68312 Cq-Include-Trybots: luci.golang.try:gotip-windows-amd64-longtest,gotip-windows-arm64 Change-Id: Ib7f77086d389cccb9d91cb77ea688d438a0ee5fd Reviewed-on: https://go-review.googlesource.com/c/go/+/605135 Reviewed-by: Dmitri Shuralyov Reviewed-by: Mauri de Souza Meneguzzo Reviewed-by: Alex Brainman Reviewed-by: Cherry Mui LUCI-TryBot-Result: Go LUCI --- .../syscall/windows/security_windows.go | 19 +++++++++++++++++++ src/os/user/lookup_windows.go | 18 +++++++++++++++--- src/os/user/user_test.go | 3 ++- 3 files changed, 36 insertions(+), 4 deletions(-) diff --git a/src/internal/syscall/windows/security_windows.go b/src/internal/syscall/windows/security_windows.go index 95694c368a..e528744caa 100644 --- a/src/internal/syscall/windows/security_windows.go +++ b/src/internal/syscall/windows/security_windows.go @@ -156,3 +156,22 @@ type UserInfo4 struct { // //go:linkname GetSystemDirectory func GetSystemDirectory() string // Implemented in runtime package. + +// GetUserName retrieves the user name of the current thread +// in the specified format. +func GetUserName(format uint32) (string, error) { + n := uint32(50) + for { + b := make([]uint16, n) + e := syscall.GetUserNameEx(format, &b[0], &n) + if e == nil { + return syscall.UTF16ToString(b[:n]), nil + } + if e != syscall.ERROR_MORE_DATA { + return "", e + } + if n <= uint32(len(b)) { + return "", e + } + } +} diff --git a/src/os/user/lookup_windows.go b/src/os/user/lookup_windows.go index f259269a53..edecac703a 100644 --- a/src/os/user/lookup_windows.go +++ b/src/os/user/lookup_windows.go @@ -232,12 +232,24 @@ func current() (*User, error) { if e != nil { return e } - username, domain, e := lookupUsernameAndDomain(u.User.Sid) + username, e := windows.GetUserName(syscall.NameSamCompatible) if e != nil { return e } - usr, e = newUser(uid, gid, dir, username, domain) - return e + displayName, e := windows.GetUserName(syscall.NameDisplay) + if e != nil { + // Historically, the username is used as fallback + // when the display name can't be retrieved. + displayName = username + } + usr = &User{ + Uid: uid, + Gid: gid, + Username: username, + Name: displayName, + HomeDir: dir, + } + return nil }) return usr, err } diff --git a/src/os/user/user_test.go b/src/os/user/user_test.go index fa597b78ec..31486aed03 100644 --- a/src/os/user/user_test.go +++ b/src/os/user/user_test.go @@ -45,8 +45,9 @@ func TestCurrent(t *testing.T) { } func BenchmarkCurrent(b *testing.B) { + // Benchmark current instead of Current because Current caches the result. for i := 0; i < b.N; i++ { - Current() + current() } } -- 2.48.1