cmd/go: factor the I/O-retry logic out of renameio

Factor the try-on-failure variants are now in the package
cmd/go/internal/robustio.

Add to them a RemoveAll variant using the same retry loop,
and use it to attempt to address the observed flakes in
TestLinkXImportPathEscape.

Fixes #19491
Updates #25965
Updates #28387
Updates #32188

Change-Id: I9db1a0c7537b8aaadccab1b9eca734595668ba29
Reviewed-on: https://go-review.googlesource.com/c/go/+/181541
Run-TryBot: Bryan C. Mills <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Alex Brainman <[email protected]>
Reviewed-by: Jay Conrod <[email protected]>
Reviewed-by: Russ Cox <[email protected]>

Author: Bryan C. Mills

src/cmd/go/go_test.go

@@ -29,6 +29,7 @@ import (
 
 	"cmd/go/internal/cache"
 	"cmd/go/internal/cfg"
+	"cmd/go/internal/robustio"
 	"cmd/internal/sys"
 )
 
@@ -685,7 +686,7 @@ func (tg *testgoData) creatingTemp(path string) {
 	if tg.wd != "" && !filepath.IsAbs(path) {
 		path = filepath.Join(tg.pwd(), path)
 	}
-	tg.must(os.RemoveAll(path))
+	tg.must(robustio.RemoveAll(path))
 	tg.temps = append(tg.temps, path)
 }
 
@@ -887,7 +888,7 @@ func removeAll(dir string) error {
 		}
 		return nil
 	})
-	return os.RemoveAll(dir)
+	return robustio.RemoveAll(dir)
 }
 
 // failSSH puts an ssh executable in the PATH that always fails.
@@ -1181,7 +1182,7 @@ func testMove(t *testing.T, vcs, url, base, config string) {
 	case "svn":
 		// SVN doesn't believe in text files so we can't just edit the config.
 		// Check out a different repo into the wrong place.
-		tg.must(os.RemoveAll(tg.path("src/code.google.com/p/rsc-svn")))
+		tg.must(robustio.RemoveAll(tg.path("src/code.google.com/p/rsc-svn")))
 		tg.run("get", "-d", "-u", "code.google.com/p/rsc-svn2/trunk")
 		tg.must(os.Rename(tg.path("src/code.google.com/p/rsc-svn2"), tg.path("src/code.google.com/p/rsc-svn")))
 	default:
@@ -1693,7 +1694,7 @@ func TestInstalls(t *testing.T) {
 	goarch := strings.TrimSpace(tg.getStdout())
 	tg.setenv("GOARCH", goarch)
 	fixbin := filepath.Join(goroot, "pkg", "tool", goos+"_"+goarch, "fix") + exeSuffix
-	tg.must(os.RemoveAll(fixbin))
+	tg.must(robustio.RemoveAll(fixbin))
 	tg.run("install", "cmd/fix")
 	tg.wantExecutable(fixbin, "did not install cmd/fix to $GOROOT/pkg/tool")
 	tg.must(os.Remove(fixbin))
@@ -2065,13 +2066,13 @@ func TestDefaultGOPATHGet(t *testing.T) {
 	tg.grepStderr("created GOPATH="+regexp.QuoteMeta(tg.path("home/go"))+"; see 'go help gopath'", "did not create GOPATH")
 
 	// no warning if directory already exists
-	tg.must(os.RemoveAll(tg.path("home/go")))
+	tg.must(robustio.RemoveAll(tg.path("home/go")))
 	tg.tempDir("home/go")
 	tg.run("get", "github.com/golang/example/hello")
 	tg.grepStderrNot(".", "expected no output on standard error")
 
 	// error if $HOME/go is a file
-	tg.must(os.RemoveAll(tg.path("home/go")))
+	tg.must(robustio.RemoveAll(tg.path("home/go")))
 	tg.tempFile("home/go", "")
 	tg.runFail("get", "github.com/golang/example/hello")
 	tg.grepStderr(`mkdir .*[/\\]go: .*(not a directory|cannot find the path)`, "expected error because $HOME/go is a file")
@@ -2872,7 +2873,7 @@ func TestCgoDependsOnSyscall(t *testing.T) {
 	files, err := filepath.Glob(filepath.Join(runtime.GOROOT(), "pkg", "*_race"))
 	tg.must(err)
 	for _, file := range files {
-		tg.check(os.RemoveAll(file))
+		tg.check(robustio.RemoveAll(file))
 	}
 	tg.tempFile("src/foo/foo.go", `
 		package foo
@@ -3925,10 +3926,10 @@ func TestGoGetDomainRoot(t *testing.T) {
 	tg.run("get", "go-get-issue-9357.appspot.com")
 	tg.run("get", "-u", "go-get-issue-9357.appspot.com")
 
-	tg.must(os.RemoveAll(tg.path("src/go-get-issue-9357.appspot.com")))
+	tg.must(robustio.RemoveAll(tg.path("src/go-get-issue-9357.appspot.com")))
 	tg.run("get", "go-get-issue-9357.appspot.com")
 
-	tg.must(os.RemoveAll(tg.path("src/go-get-issue-9357.appspot.com")))
+	tg.must(robustio.RemoveAll(tg.path("src/go-get-issue-9357.appspot.com")))
 	tg.run("get", "-u", "go-get-issue-9357.appspot.com")
 }
 
@@ -4513,8 +4514,9 @@ func TestLinkXImportPathEscape(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.parallel()
+	tg.makeTempdir()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	exe := "./linkx" + exeSuffix
+	exe := tg.path("linkx" + exeSuffix)
 	tg.creatingTemp(exe)
 	tg.run("build", "-o", exe, "-ldflags", "-X=my.pkg.Text=linkXworked", "my.pkg/main")
 	out, err := exec.Command(exe).CombinedOutput()
@@ -4750,7 +4752,7 @@ func TestExecutableGOROOT(t *testing.T) {
 		check(t, symGoTool, newRoot)
 	})
 
-	tg.must(os.RemoveAll(tg.path("new/pkg")))
+	tg.must(robustio.RemoveAll(tg.path("new/pkg")))
 
 	// Binaries built in the new tree should report the
 	// new tree when they call runtime.GOROOT.
@@ -5101,7 +5103,7 @@ func TestExecBuildX(t *testing.T) {
 	if len(matches) == 0 {
 		t.Fatal("no WORK directory")
 	}
-	tg.must(os.RemoveAll(matches[1]))
+	tg.must(robustio.RemoveAll(matches[1]))
 }
 
 func TestParallelNumber(t *testing.T) {

src/cmd/go/go_windows_test.go

@@ -12,6 +12,8 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+
+	"cmd/go/internal/robustio"
 )
 
 func TestAbsolutePath(t *testing.T) {
@@ -21,7 +23,7 @@ func TestAbsolutePath(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer os.RemoveAll(tmp)
+	defer robustio.RemoveAll(tmp)
 
 	file := filepath.Join(tmp, "a.go")
 	err = ioutil.WriteFile(file, []byte{}, 0644)

src/cmd/go/internal/renameio/renameio.go

@@ -12,6 +12,8 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+
+	"cmd/go/internal/robustio"
 )
 
 const patternSuffix = ".tmp"
@@ -61,7 +63,7 @@ func WriteToFile(filename string, data io.Reader, perm os.FileMode) (err error)
 		return err
 	}
 
-	return rename(f.Name(), filename)
+	return robustio.Rename(f.Name(), filename)
 }
 
 // ReadFile is like ioutil.ReadFile, but on Windows retries spurious errors that
@@ -74,7 +76,7 @@ func WriteToFile(filename string, data io.Reader, perm os.FileMode) (err error)
 // 	- syscall.ERROR_FILE_NOT_FOUND
 // 	- internal/syscall/windows.ERROR_SHARING_VIOLATION
 func ReadFile(filename string) ([]byte, error) {
-	return readFile(filename)
+	return robustio.ReadFile(filename)
 }
 
 // tempFile creates a new temporary file with given permission bits.

src/cmd/go/internal/renameio/renameio_test.go

@@ -19,6 +19,8 @@ import (
 	"syscall"
 	"testing"
 	"time"
+
+	"cmd/go/internal/robustio"
 )
 
 func TestConcurrentReadsAndWrites(t *testing.T) {
@@ -58,7 +60,7 @@ func TestConcurrentReadsAndWrites(t *testing.T) {
 			chunk := buf[offset*8 : (offset+chunkWords)*8]
 			if err := WriteFile(path, chunk, 0666); err == nil {
 				atomic.AddInt64(&writeSuccesses, 1)
-			} else if isEphemeralError(err) {
+			} else if robustio.IsEphemeralError(err) {
 				var (
 					errno syscall.Errno
 					dup   bool
@@ -74,10 +76,10 @@ func TestConcurrentReadsAndWrites(t *testing.T) {
 			}
 
 			time.Sleep(time.Duration(rand.Intn(100)) * time.Microsecond)
-			data, err := ioutil.ReadFile(path)
+			data, err := ReadFile(path)
 			if err == nil {
 				atomic.AddInt64(&readSuccesses, 1)
-			} else if isEphemeralError(err) {
+			} else if robustio.IsEphemeralError(err) {
 				var (
 					errno syscall.Errno
 					dup   bool

src/cmd/go/internal/robustio/robustio.go

@@ -0,0 +1,53 @@
+// 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 wraps I/O functions that are prone to failure on Windows,
+// transparently retrying errors up to an arbitrary timeout.
+//
+// Errors are classified heuristically and retries are bounded, so the functions
+// in this package do not completely eliminate spurious errors. However, they do
+// significantly reduce the rate of failure in practice.
+//
+// If so, the error will likely wrap one of:
+// The functions in this package do not completely eliminate spurious errors,
+// but substantially reduce their rate of occurrence in practice.
+package robustio
+
+// Rename is like os.Rename, but on Windows retries errors that may occur if the
+// file is concurrently read or overwritten.
+//
+// (See golang.org/issue/31247 and golang.org/issue/32188.)
+func Rename(oldpath, newpath string) error {
+	return rename(oldpath, newpath)
+}
+
+// ReadFile is like ioutil.ReadFile, but on Windows retries errors that may
+// occur if the file is concurrently replaced.
+//
+// (See golang.org/issue/31247 and golang.org/issue/32188.)
+func ReadFile(filename string) ([]byte, error) {
+	return readFile(filename)
+}
+
+// RemoveAll is like os.RemoveAll, but on Windows retries errors that may occur
+// if an executable file in the directory has recently been executed.
+//
+// (See golang.org/issue/19491.)
+func RemoveAll(path string) error {
+	return removeAll(path)
+}
+
+// IsEphemeralError reports whether err is one of the errors that the functions
+// in this package attempt to mitigate.
+//
+// Errors considered ephemeral include:
+// 	- syscall.ERROR_ACCESS_DENIED
+// 	- syscall.ERROR_FILE_NOT_FOUND
+// 	- internal/syscall/windows.ERROR_SHARING_VIOLATION
+//
+// This set may be expanded in the future; programs must not rely on the
+// non-ephemerality of any given error.
+func IsEphemeralError(err error) bool {
+	return isEphemeralError(err)
+}

src/cmd/go/internal/renameio/rename.go renamed to src/cmd/go/internal/robustio/robustio_other.go

@@ -4,7 +4,7 @@
 
 //+build !windows
 
-package renameio
+package robustio
 
 import (
 	"io/ioutil"
@@ -19,6 +19,10 @@ func readFile(filename string) ([]byte, error) {
 	return ioutil.ReadFile(filename)
 }
 
+func removeAll(path string) error {
+	return os.RemoveAll(path)
+}
+
 func isEphemeralError(err error) bool {
 	return false
 }

src/cmd/go/internal/renameio/rename_windows.go renamed to src/cmd/go/internal/robustio/robustio_windows.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.
 
-package renameio
+package robustio
 
 import (
 	"errors"
@@ -14,9 +14,10 @@ import (
 	"time"
 )
 
+const arbitraryTimeout = 500 * time.Millisecond
+
 // retry retries ephemeral errors from f up to an arbitrary timeout
 // to work around spurious filesystem errors on Windows
-// (see golang.org/issue/31247 and golang.org/issue/32188).
 func retry(f func() (err error, mayRetry bool)) error {
 	var (
 		bestErr     error
@@ -40,7 +41,7 @@ func retry(f func() (err error, mayRetry bool)) error {
 
 		if start.IsZero() {
 			start = time.Now()
-		} else if d := time.Since(start) + nextSleep; d >= 500*time.Millisecond {
+		} else if d := time.Since(start) + nextSleep; d >= arbitraryTimeout {
 			break
 		}
 		time.Sleep(nextSleep)
@@ -61,8 +62,6 @@ func retry(f func() (err error, mayRetry bool)) error {
 //
 // Empirical error rates with MoveFileEx are lower under modest concurrency, so
 // for now we're sticking with what the os package already provides.
-//
-// TODO(bcmills): For Go 1.14, should we try changing os.Rename itself to do this?
 func rename(oldpath, newpath string) (err error) {
 	return retry(func() (err error, mayRetry bool) {
 		err = os.Rename(oldpath, newpath)
@@ -71,8 +70,6 @@ func rename(oldpath, newpath string) (err error) {
 }
 
 // readFile is like ioutil.ReadFile, but retries ephemeral errors.
-//
-// TODO(bcmills): For Go 1.14, should we try changing ioutil.ReadFile itself to do this?
 func readFile(filename string) ([]byte, error) {
 	var b []byte
 	err := retry(func() (err error, mayRetry bool) {
@@ -86,6 +83,13 @@ func readFile(filename string) ([]byte, error) {
 	return b, err
 }
 
+func removeAll(path string) error {
+	return retry(func() (err error, mayRetry bool) {
+		err = os.RemoveAll(path)
+		return err, isEphemeralError(err)
+	})
+}
+
 // isEphemeralError returns true if err may be resolved by waiting.
 func isEphemeralError(err error) bool {
 	var errno syscall.Errno

src/cmd/go/script_test.go

@@ -27,6 +27,7 @@ import (
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/imports"
 	"cmd/go/internal/par"
+	"cmd/go/internal/robustio"
 	"cmd/go/internal/txtar"
 	"cmd/go/internal/work"
 )
@@ -388,7 +389,7 @@ func (ts *testScript) cmdCc(neg bool, args []string) {
 	var b work.Builder
 	b.Init()
 	ts.cmdExec(neg, append(b.GccCmd(".", ""), args...))
-	os.RemoveAll(b.WorkDir)
+	robustio.RemoveAll(b.WorkDir)
 }
 
 // cd changes to a different directory.
@@ -669,8 +670,8 @@ func (ts *testScript) cmdRm(neg bool, args []string) {
 	}
 	for _, arg := range args {
 		file := ts.mkabs(arg)
-		removeAll(file)              // does chmod and then attempts rm
-		ts.check(os.RemoveAll(file)) // report error
+		removeAll(file)                    // does chmod and then attempts rm
+		ts.check(robustio.RemoveAll(file)) // report error
 	}
 }