all: fix touching of dependency directories

Adjust the setup script in integration_test.go to better keep
track of what directories are in current use.
Previously, the staticcheck directory was not tracked as used,
causing it to be deleted unnecessarily.

We ensure consistent tracking, but having each depedency setup step
start with a startWork call, and end with a finishWork call.

Change-Id: I4f5d929f323509237f4f44ed8f57d71b8756f031
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/253617
Reviewed-by: Damien Neil <dneil@google.com>

integration_test.go

@@ -202,50 +202,54 @@ func mustInitDeps(t *testing.T) {
 	// Delete the current directory if non-empty,
 	// which only occurs if a dependency failed to initialize properly.
 	var workingDir string
+	finishedDirs := map[string]bool{}
 	defer func() {
 		if workingDir != "" {
 			os.RemoveAll(workingDir) // best-effort
 		}
 	}()
+	startWork := func(name string) string {
+		workingDir = filepath.Join(testDir, name)
+		return workingDir
+	}
+	finishWork := func() {
+		finishedDirs[workingDir] = true
+		workingDir = ""
+	}
 
 	// Delete other sub-directories that are no longer relevant.
 	defer func() {
-		subDirs := map[string]bool{"bin": true, "gopath": true}
-		subDirs["protobuf-"+protobufVersion] = true
-		for _, v := range golangVersions {
-			subDirs["go"+v] = true
-		}
-
 		now := time.Now()
 		fis, _ := ioutil.ReadDir(testDir)
 		for _, fi := range fis {
-			if subDirs[fi.Name()] {
+			dir := filepath.Join(testDir, fi.Name())
-				os.Chtimes(filepath.Join(testDir, fi.Name()), now, now) // best-effort
+			if finishedDirs[dir] {
+				os.Chtimes(dir, now, now) // best-effort
 				continue
 			}
 			if now.Sub(fi.ModTime()) < purgeTimeout {
 				continue
 			}
 			fmt.Printf("delete %v\n", fi.Name())
-			os.RemoveAll(filepath.Join(testDir, fi.Name())) // best-effort
+			os.RemoveAll(dir) // best-effort
 		}
 	}()
 
 	// The bin directory contains symlinks to each tool by version.
 	// It is safe to delete this directory and run the test script from scratch.
-	binPath := filepath.Join(testDir, "bin")
+	binPath := startWork("bin")
 	check(os.RemoveAll(binPath))
 	check(os.Mkdir(binPath, 0775))
 	check(os.Setenv("PATH", binPath+":"+os.Getenv("PATH")))
 	registerBinary := func(name, path string) {
 		check(os.Symlink(path, filepath.Join(binPath, name)))
 	}
+	finishWork()
 
 	// Download and build the protobuf toolchain.
 	// We avoid downloading the pre-compiled binaries since they do not contain
 	// the conformance test runner.
-	workingDir = filepath.Join(testDir, "protobuf-"+protobufVersion)
+	protobufPath = startWork("protobuf-" + protobufVersion)
-	protobufPath = workingDir
 	if _, err := os.Stat(protobufPath); err != nil {
 		fmt.Printf("download %v\n", filepath.Base(protobufPath))
 		if isCommit := strings.Trim(protobufVersion, "0123456789abcdef") == ""; isCommit {
@@ -265,31 +269,31 @@ func mustInitDeps(t *testing.T) {
 	check(os.Setenv("PROTOBUF_ROOT", protobufPath)) // for generate-protos
 	registerBinary("conform-test-runner", filepath.Join(protobufPath, "conformance", "conformance-test-runner"))
 	registerBinary("protoc", filepath.Join(protobufPath, "src", "protoc"))
-	workingDir = ""
+	finishWork()
 
 	// Download each Go toolchain version.
 	for _, v := range golangVersions {
-		workingDir = filepath.Join(testDir, "go"+v)
+		goDir := startWork("go" + v)
-		if _, err := os.Stat(workingDir); err != nil {
+		if _, err := os.Stat(goDir); err != nil {
-			fmt.Printf("download %v\n", filepath.Base(workingDir))
+			fmt.Printf("download %v\n", filepath.Base(goDir))
 			url := fmt.Sprintf("https://dl.google.com/go/go%v.%v-%v.tar.gz", v, runtime.GOOS, runtime.GOARCH)
-			downloadArchive(check, workingDir, url, "go", "") // skip SHA256 check as we fetch over https from a trusted domain
+			downloadArchive(check, goDir, url, "go", "") // skip SHA256 check as we fetch over https from a trusted domain
 		}
-		registerBinary("go"+v, filepath.Join(workingDir, "bin", "go"))
+		registerBinary("go"+v, filepath.Join(goDir, "bin", "go"))
+		finishWork()
 	}
 	registerBinary("go", filepath.Join(testDir, "go"+golangLatest, "bin", "go"))
 	registerBinary("gofmt", filepath.Join(testDir, "go"+golangLatest, "bin", "gofmt"))
-	workingDir = ""
 
 	// Download the staticcheck tool.
-	workingDir = filepath.Join(testDir, "staticcheck-"+staticcheckVersion)
+	checkDir := startWork("staticcheck-" + staticcheckVersion)
-	if _, err := os.Stat(workingDir); err != nil {
+	if _, err := os.Stat(checkDir); err != nil {
-		fmt.Printf("download %v\n", filepath.Base(workingDir))
+		fmt.Printf("download %v\n", filepath.Base(checkDir))
 		url := fmt.Sprintf("https://github.com/dominikh/go-tools/releases/download/%v/staticcheck_%v_%v.tar.gz", staticcheckVersion, runtime.GOOS, runtime.GOARCH)
-		downloadArchive(check, workingDir, url, "staticcheck", staticcheckSHA256s[runtime.GOOS+"/"+runtime.GOARCH])
+		downloadArchive(check, checkDir, url, "staticcheck", staticcheckSHA256s[runtime.GOOS+"/"+runtime.GOARCH])
 	}
-	registerBinary("staticcheck", filepath.Join(workingDir, "staticcheck"))
+	registerBinary("staticcheck", filepath.Join(checkDir, "staticcheck"))
-	workingDir = ""
+	finishWork()
 
 	// Travis-CI sets GOROOT, which confuses invocations of the Go toolchain.
 	// Explicitly clear GOROOT, so each toolchain uses their default GOROOT.
@@ -299,7 +303,7 @@ func mustInitDeps(t *testing.T) {
 	check(os.Setenv("GOCACHE", filepath.Join(repoRoot, ".gocache")))
 
 	// Setup GOPATH for pre-module support (i.e., go1.10 and earlier).
-	goPath = filepath.Join(testDir, "gopath")
+	goPath = startWork("gopath")
 	modulePath = strings.TrimSpace(command{Dir: testDir}.mustRun(t, "go", "list", "-m", "-f", "{{.Path}}"))
 	check(os.RemoveAll(filepath.Join(goPath, "src")))
 	check(os.MkdirAll(filepath.Join(goPath, "src", filepath.Dir(modulePath)), 0775))
@@ -307,6 +311,7 @@ func mustInitDeps(t *testing.T) {
 	command{Dir: repoRoot}.mustRun(t, "go", "mod", "tidy")
 	command{Dir: repoRoot}.mustRun(t, "go", "mod", "vendor")
 	check(os.Setenv("GOPATH", goPath))
+	finishWork()
 }
 
 func downloadFile(check func(error), dstPath, srcURL string) {