internal/renameio, internal/robustio: import upstream changes

This imports the following commits from upstream:

commit a38a917aee626a9b9d5ce2b93964f586bf759ea0
all: remove the nacl port (part 1)

commit 9cce08d72470eb6ae2a2870bb9c70d1893441b0f
cmd/go/internal/renameio,runtime: avoid leaking temp directory in test

commit 033299fab66b08d434be30e05d11f7db63efa71c
all: add a space before +build in build tag comments

commit 81c6bac06f5f8a45f0837cb42b2793df64de08a7
cmd/go/internal/robustio: extend filesystem workarounds to darwin platforms

internal/renameio/renameio_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !plan9
+// +build !plan9
 
 package renameio
 
@@ -128,10 +128,18 @@ func TestConcurrentReadsAndWrites(t *testing.T) {
 	}
 
 	var minReadSuccesses int64 = attempts
-	if runtime.GOOS == "windows" {
+
+	switch runtime.GOOS {
+	case "windows":
 		// Windows produces frequent "Access is denied" errors under heavy rename load.
-		// As long as those are the only errors and *some* of the writes succeed, we're happy.
+		// As long as those are the only errors and *some* of the reads succeed, we're happy.
 		minReadSuccesses = attempts / 4
+
+	case "darwin":
+		// The filesystem on macOS 10.14 occasionally fails with "no such file or
+		// directory" errors. See https://golang.org/issue/33041. The flake rate is
+		// fairly low, so ensure that at least 75% of attempts succeed.
+		minReadSuccesses = attempts - (attempts / 4)
 	}
 
 	if readSuccesses < minReadSuccesses {

internal/renameio/umask_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !nacl,!plan9,!windows,!js
+// +build !plan9,!windows,!js
 
 package renameio
 
@@ -19,6 +19,7 @@ func TestWriteFileModeAppliesUmask(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to create temporary directory: %v", err)
 	}
+	defer os.RemoveAll(dir)
 
 	const mode = 0644
 	const umask = 0007
@@ -29,7 +30,6 @@ func TestWriteFileModeAppliesUmask(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to write file: %v", err)
 	}
-	defer os.RemoveAll(dir)
 
 	fi, err := os.Stat(file)
 	if err != nil {

internal/robustio/robustio_darwin.go

@@ -0,0 +1,29 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package robustio
+
+import (
+	"os"
+	"syscall"
+)
+
+const errFileNotFound = syscall.ENOENT
+
+// isEphemeralError returns true if err may be resolved by waiting.
+func isEphemeralError(err error) bool {
+	switch werr := err.(type) {
+	case *os.PathError:
+		err = werr.Err
+	case *os.LinkError:
+		err = werr.Err
+	case *os.SyscallError:
+		err = werr.Err
+
+	}
+	if errno, ok := err.(syscall.Errno); ok {
+		return errno == errFileNotFound
+	}
+	return false
+}

internal/robustio/robustio_flaky.go

@@ -0,0 +1,93 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows darwin
+
+package robustio
+
+import (
+	"io/ioutil"
+	"math/rand"
+	"os"
+	"syscall"
+	"time"
+)
+
+const arbitraryTimeout = 500 * time.Millisecond
+
+const ERROR_SHARING_VIOLATION = 32
+
+// retry retries ephemeral errors from f up to an arbitrary timeout
+// to work around filesystem flakiness on Windows and Darwin.
+func retry(f func() (err error, mayRetry bool)) error {
+	var (
+		bestErr     error
+		lowestErrno syscall.Errno
+		start       time.Time
+		nextSleep   time.Duration = 1 * time.Millisecond
+	)
+	for {
+		err, mayRetry := f()
+		if err == nil || !mayRetry {
+			return err
+		}
+
+		if errno, ok := err.(syscall.Errno); ok && (lowestErrno == 0 || errno < lowestErrno) {
+			bestErr = err
+			lowestErrno = errno
+		} else if bestErr == nil {
+			bestErr = err
+		}
+
+		if start.IsZero() {
+			start = time.Now()
+		} else if d := time.Since(start) + nextSleep; d >= arbitraryTimeout {
+			break
+		}
+		time.Sleep(nextSleep)
+		nextSleep += time.Duration(rand.Int63n(int64(nextSleep)))
+	}
+
+	return bestErr
+}
+
+// rename is like os.Rename, but retries ephemeral errors.
+//
+// On windows it wraps os.Rename, which (as of 2019-06-04) uses MoveFileEx with
+// MOVEFILE_REPLACE_EXISTING.
+//
+// Windows also provides a different system call, ReplaceFile,
+// that provides similar semantics, but perhaps preserves more metadata. (The
+// documentation on the differences between the two is very sparse.)
+//
+// Empirical error rates with MoveFileEx are lower under modest concurrency, so
+// for now we're sticking with what the os package already provides.
+func rename(oldpath, newpath string) (err error) {
+	return retry(func() (err error, mayRetry bool) {
+		err = os.Rename(oldpath, newpath)
+		return err, isEphemeralError(err)
+	})
+}
+
+// readFile is like ioutil.ReadFile, but retries ephemeral errors.
+func readFile(filename string) ([]byte, error) {
+	var b []byte
+	err := retry(func() (err error, mayRetry bool) {
+		b, err = ioutil.ReadFile(filename)
+
+		// Unlike in rename, we do not retry errFileNotFound here: it can occur
+		// as a spurious error, but the file may also genuinely not exist, so the
+		// increase in robustness is probably not worth the extra latency.
+
+		return err, isEphemeralError(err) && err != errFileNotFound
+	})
+	return b, err
+}
+
+func removeAll(path string) error {
+	return retry(func() (err error, mayRetry bool) {
+		err = os.RemoveAll(path)
+		return err, isEphemeralError(err)
+	})
+}

internal/robustio/robustio_other.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !windows
+//+build !windows,!darwin
 
 package robustio
 

internal/robustio/robustio_windows.go

@@ -5,90 +5,11 @@
 package robustio
 
 import (
-	"io/ioutil"
-	"math/rand"
 	"os"
 	"syscall"
-	"time"
 )
 
-const arbitraryTimeout = 500 * time.Millisecond
-
-const ERROR_SHARING_VIOLATION = 32
-
-// retry retries ephemeral errors from f up to an arbitrary timeout
-// to work around spurious filesystem errors on Windows
-func retry(f func() (err error, mayRetry bool)) error {
-	var (
-		bestErr     error
-		lowestErrno syscall.Errno
-		start       time.Time
-		nextSleep   time.Duration = 1 * time.Millisecond
-	)
-	for {
-		err, mayRetry := f()
-		if err == nil || !mayRetry {
-			return err
-		}
-
-		if errno, ok := err.(syscall.Errno); ok && (lowestErrno == 0 || errno < lowestErrno) {
-			bestErr = err
-			lowestErrno = errno
-		} else if bestErr == nil {
-			bestErr = err
-		}
-
-		if start.IsZero() {
-			start = time.Now()
-		} else if d := time.Since(start) + nextSleep; d >= arbitraryTimeout {
-			break
-		}
-		time.Sleep(nextSleep)
-		nextSleep += time.Duration(rand.Int63n(int64(nextSleep)))
-	}
-
-	return bestErr
-}
-
-// rename is like os.Rename, but retries ephemeral errors.
-//
-// It wraps os.Rename, which (as of 2019-06-04) uses MoveFileEx with
-// MOVEFILE_REPLACE_EXISTING.
-//
-// Windows also provides a different system call, ReplaceFile,
-// that provides similar semantics, but perhaps preserves more metadata. (The
-// documentation on the differences between the two is very sparse.)
-//
-// Empirical error rates with MoveFileEx are lower under modest concurrency, so
-// for now we're sticking with what the os package already provides.
-func rename(oldpath, newpath string) (err error) {
-	return retry(func() (err error, mayRetry bool) {
-		err = os.Rename(oldpath, newpath)
-		return err, isEphemeralError(err)
-	})
-}
-
-// readFile is like ioutil.ReadFile, but retries ephemeral errors.
-func readFile(filename string) ([]byte, error) {
-	var b []byte
-	err := retry(func() (err error, mayRetry bool) {
-		b, err = ioutil.ReadFile(filename)
-
-		// Unlike in rename, we do not retry ERROR_FILE_NOT_FOUND here: it can occur
-		// as a spurious error, but the file may also genuinely not exist, so the
-		// increase in robustness is probably not worth the extra latency.
-
-		return err, isEphemeralError(err) && err != syscall.ERROR_FILE_NOT_FOUND
-	})
-	return b, err
-}
-
-func removeAll(path string) error {
-	return retry(func() (err error, mayRetry bool) {
-		err = os.RemoveAll(path)
-		return err, isEphemeralError(err)
-	})
-}
+const errFileNotFound = syscall.ERROR_FILE_NOT_FOUND
 
 // isEphemeralError returns true if err may be resolved by waiting.
 func isEphemeralError(err error) bool {