go/build: replace ioutil.ReadDir with os.ReadDir

Change go/build.readDir to use os.ReadDir instead of ioutil.ReadDir.
This addresses a TODO and improves performance on Darwin and Linux.

Darwin: Apple M1
name              old time/op    new time/op    delta
ImportVendor-10     39.8µs ± 1%    37.0µs ± 1%  -6.91%  (p=0.000 n=10+10)

Linux: Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz
name              old time/op    new time/op    delta
ImportVendor-16     22.9µs ±11%    21.2µs ± 5%  -7.47%  (p=0.001 n=10+9)

Updates #45557

Change-Id: Ib1bd2e66210e714e499a035847d6261b61b7e2c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/392074
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>

diff --git a/src/go/build/build.go b/src/go/build/build.go
index 836e279d924f2798bf46080eeda104a34380e955..039b422dabb21d00ecd64d39cb62855d602f15f5 100644 (file)
--- a/src/go/build/build.go
+++ b/src/go/build/build.go
@@ -17,7 +17,6 @@ import (
        "internal/goversion"
        "io"
        "io/fs"
-       "io/ioutil"
        "os"
        "os/exec"
        pathpkg "path"
@@ -186,13 +185,21 @@ func hasSubdir(root, dir string) (rel string, ok bool) {
        return filepath.ToSlash(dir[len(root):]), true
 }
 
-// readDir calls ctxt.ReadDir (if not nil) or else ioutil.ReadDir.
-func (ctxt *Context) readDir(path string) ([]fs.FileInfo, error) {
+// readDir calls ctxt.ReadDir (if not nil) or else os.ReadDir.
+func (ctxt *Context) readDir(path string) ([]fs.DirEntry, error) {
+       // TODO: add a fs.DirEntry version of Context.ReadDir
        if f := ctxt.ReadDir; f != nil {
-               return f(path)
+               fis, err := f(path)
+               if err != nil {
+                       return nil, err
+               }
+               des := make([]fs.DirEntry, len(fis))
+               for i, fi := range fis {
+                       des[i] = fs.FileInfoToDirEntry(fi)
+               }
+               return des, nil
        }
-       // TODO: use os.ReadDir
-       return ioutil.ReadDir(path)
+       return os.ReadDir(path)
 }
 
 // openFile calls ctxt.OpenFile (if not nil) or else os.Open.
@@ -836,7 +843,7 @@ Found:
                if d.IsDir() {
                        continue
                }
-               if d.Mode()&fs.ModeSymlink != 0 {
+               if d.Type() == fs.ModeSymlink {
                        if ctxt.isDir(ctxt.joinPath(p.Dir, d.Name())) {
                                // Symlinks to directories are not source files.
                                continue

diff --git a/src/go/build/build_test.go b/src/go/build/build_test.go
index 36bcae179e3252f1f152e5191ae523992e6a166f..8fa17c7343e64ae31d7420a08f80ef293a32cb48 100644 (file)
--- a/src/go/build/build_test.go
+++ b/src/go/build/build_test.go
@@ -567,6 +567,27 @@ func TestImportVendor(t *testing.T) {
        }
 }
 
+func BenchmarkImportVendor(b *testing.B) {
+       testenv.MustHaveGoBuild(b) // really must just have source
+
+       b.Setenv("GO111MODULE", "off")
+
+       ctxt := Default
+       wd, err := os.Getwd()
+       if err != nil {
+               b.Fatal(err)
+       }
+       ctxt.GOPATH = filepath.Join(wd, "testdata/withvendor")
+       dir := filepath.Join(ctxt.GOPATH, "src/a/b")
+       b.ResetTimer()
+       for i := 0; i < b.N; i++ {
+               _, err := ctxt.Import("c/d", dir, 0)
+               if err != nil {
+                       b.Fatalf("cannot find vendored c/d from testdata src/a/b directory: %v", err)
+               }
+       }
+}
+
 func TestImportVendorFailure(t *testing.T) {
        testenv.MustHaveGoBuild(t) // really must just have source