From b822f098c557ea3d9200fd2d8a2e2b4d641e83e4 Mon Sep 17 00:00:00 2001 From: Peter Collingbourne Date: Mon, 11 Mar 2024 20:10:48 -0700 Subject: [PATCH] os: don't try to make the directory FD non-blocking in os.ReadDir MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This will fail because epoll_ctl() fails on directory FDs, so we end up issuing unnecessary syscalls. My test program that calls filepath.WalkDir on a large directory tree runs 1.23 ± 0.04 times faster than with the original implementation. Change-Id: Ie33d798c48057a7b2d0bacac80fcdde5b5a8bb1b Reviewed-on: https://go-review.googlesource.com/c/go/+/570877 LUCI-TryBot-Result: Go LUCI Auto-Submit: Ian Lance Taylor Reviewed-by: Ian Lance Taylor --- src/os/dir.go | 2 +- src/os/file.go | 8 ++++++++ src/os/file_plan9.go | 4 ++++ src/os/file_unix.go | 30 ++++++++++++++++++++++++++++-- src/os/file_windows.go | 4 ++++ 5 files changed, 45 insertions(+), 3 deletions(-) diff --git a/src/os/dir.go b/src/os/dir.go index 9124de29e8..dcc18e1814 100644 --- a/src/os/dir.go +++ b/src/os/dir.go @@ -115,7 +115,7 @@ var testingForceReadDirLstat bool // ReadDir returns the entries it was able to read before the error, // along with the error. func ReadDir(name string) ([]DirEntry, error) { - f, err := Open(name) + f, err := openDir(name) if err != nil { return nil, err } diff --git a/src/os/file.go b/src/os/file.go index c0c972bbd7..fae7bf1039 100644 --- a/src/os/file.go +++ b/src/os/file.go @@ -380,6 +380,14 @@ func OpenFile(name string, flag int, perm FileMode) (*File, error) { return f, nil } +// openDir opens a file which is assumed to be a directory. As such, it skips +// the syscalls that make the file descriptor non-blocking as these take time +// and will fail on file descriptors for directories. +func openDir(name string) (*File, error) { + testlog.Open(name) + return openDirNolog(name) +} + // lstat is overridden in tests. var lstat = Lstat diff --git a/src/os/file_plan9.go b/src/os/file_plan9.go index 69a24316e6..477674b80a 100644 --- a/src/os/file_plan9.go +++ b/src/os/file_plan9.go @@ -139,6 +139,10 @@ func openFileNolog(name string, flag int, perm FileMode) (*File, error) { return NewFile(uintptr(fd), name), nil } +func openDirNolog(name string) (*File, error) { + return openFileNolog(name, O_RDONLY, 0) +} + // Close closes the File, rendering it unusable for I/O. // On files that support SetDeadline, any pending I/O operations will // be canceled and return immediately with an ErrClosed error. diff --git a/src/os/file_unix.go b/src/os/file_unix.go index 6597186486..924ec25ed9 100644 --- a/src/os/file_unix.go +++ b/src/os/file_unix.go @@ -157,7 +157,7 @@ const ( kindNonBlock // kindNoPoll means that we should not put the descriptor into // non-blocking mode, because we know it is not a pipe or FIFO. - // Used by openFdAt for directories. + // Used by openFdAt and openDirNolog for directories. kindNoPoll ) @@ -256,7 +256,7 @@ func epipecheck(file *File, e error) { const DevNull = "/dev/null" // openFileNolog is the Unix implementation of OpenFile. -// Changes here should be reflected in openFdAt, if relevant. +// Changes here should be reflected in openFdAt and openDirNolog, if relevant. func openFileNolog(name string, flag int, perm FileMode) (*File, error) { setSticky := false if !supportsCreateWithStickyBit && flag&O_CREATE != 0 && perm&ModeSticky != 0 { @@ -303,6 +303,32 @@ func openFileNolog(name string, flag int, perm FileMode) (*File, error) { return f, nil } +func openDirNolog(name string) (*File, error) { + var r int + var s poll.SysFile + for { + var e error + r, s, e = open(name, O_RDONLY|syscall.O_CLOEXEC, 0) + if e == nil { + break + } + + if e == syscall.EINTR { + continue + } + + return nil, &PathError{Op: "open", Path: name, Err: e} + } + + if !supportsCloseOnExec { + syscall.CloseOnExec(r) + } + + f := newFile(r, name, kindNoPoll) + f.pfd.SysFile = s + return f, nil +} + func (file *file) close() error { if file == nil { return syscall.EINVAL diff --git a/src/os/file_windows.go b/src/os/file_windows.go index fcdb5f2e8f..a304a5e4a7 100644 --- a/src/os/file_windows.go +++ b/src/os/file_windows.go @@ -119,6 +119,10 @@ func openFileNolog(name string, flag int, perm FileMode) (*File, error) { return newFile(r, name, "file"), nil } +func openDirNolog(name string) (*File, error) { + return openFileNolog(name, O_RDONLY, 0) +} + func (file *file) close() error { if file == nil { return syscall.EINVAL -- 2.50.0