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imports: do less I/O finding the package name of an import
When goimports was run on a file like: package main import ( "example.net/foo" "example.net/bar" ) var _, _ = foo.Foo, bar.Bar ... even though there looks to be no work to do, it still needs to verify that "example.net/foo" is really package "foo" (even though it looks like it) and "example.net/bar" is really package "bar". (Packages in the standard library are hard-coded since the previous commit and not verified for consistency since they're always consistent) To do that verification for non-std packages, go/build.Import was being used before, but Import reads all files in the directory to make sure they're consistent. That's unnecessary. Instead, stop after the first file. If example.net/foo has foo.go with "package foo" and just_kidding.go with "package other", we never read that far to find the inconsistency. Oh well. Prefer speed. Updates golang/go#16367 Change-Id: I9fc3fefbee0e8a6bc287bf2a565257fb9523fd5c Reviewed-on: https://go-review.googlesource.com/24948 Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
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@ -187,29 +187,72 @@ func importPathToNameGoPath(importPath, srcDir string) (packageName string) {
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return pkg
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return pkg
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}
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}
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// TODO(bradfitz): build.Import does too much work, and
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pkgName, err := importPathToNameGoPathParse(importPath, srcDir)
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// doesn't cache either in-process or long-lived (anything
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// found in the first pass from explicit imports aren't used
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// again when scanning all directories). Also, it opens+reads
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// *_test.go files too. As a baby step, use a cheaper
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// mechanism to start (build.FindOnly), and then just read a
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// single file (like parser.ParseFile in loadExportsGoPath) and
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// skip only "documentation" but otherwise trust the first matching
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// file's package name.
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if Debug {
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if Debug {
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log.Printf("build.Import(ip=%q, srcDir=%q) ...", importPath, srcDir)
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log.Printf("importPathToNameGoPathParse(%q, srcDir=%q) = %q, %v", importPath, srcDir, pkgName, err)
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}
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}
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if buildPkg, err := build.Import(importPath, srcDir, 0); err == nil {
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if err == nil {
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if Debug {
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return pkgName
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log.Printf("build.Import(%q, srcDir=%q) = %q", importPath, srcDir, buildPkg.Name)
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}
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return buildPkg.Name
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} else {
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if Debug {
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log.Printf("build.Import(%q, srcDir=%q) error: %v", importPath, srcDir, err)
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}
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}
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return importPathToNameBasic(importPath, srcDir)
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return importPathToNameBasic(importPath, srcDir)
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}
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// importPathToNameGoPathParse is a faster version of build.Import if
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// the only thing desired is the package name. It uses build.FindOnly
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// to find the directory and then only parses one file in the package,
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// trusting that the files in the directory are consistent.
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func importPathToNameGoPathParse(importPath, srcDir string) (packageName string, err error) {
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buildPkg, err := build.Import(importPath, srcDir, build.FindOnly)
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if err != nil {
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return "", err
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}
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}
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d, err := os.Open(buildPkg.Dir)
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if err != nil {
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return "", err
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}
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names, err := d.Readdirnames(-1)
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d.Close()
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if err != nil {
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return "", err
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}
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sort.Strings(names) // to have predictable behavior
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var lastErr error
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var nfile int
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for _, name := range names {
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if !strings.HasSuffix(name, ".go") {
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continue
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}
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if strings.HasSuffix(name, "_test.go") {
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continue
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}
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nfile++
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fullFile := filepath.Join(buildPkg.Dir, name)
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fset := token.NewFileSet()
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f, err := parser.ParseFile(fset, fullFile, nil, parser.PackageClauseOnly)
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if err != nil {
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lastErr = err
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continue
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}
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pkgName := f.Name.Name
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if pkgName == "documentation" {
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// Special case from go/build.ImportDir, not
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// handled by ctx.MatchFile.
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continue
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}
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if pkgName == "main" {
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// Also skip package main, assuming it's a
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// +build ignore generator or example. Since
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// you can't import a package main anyway,
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// there's no harm here.
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continue
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}
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return pkgName, nil
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}
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if lastErr != nil {
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return "", lastErr
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}
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return "", fmt.Errorf("no importable package found in %d Go files", nfile)
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}
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}
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var stdImportPackage = map[string]string{} // "net/http" => "http"
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var stdImportPackage = map[string]string{} // "net/http" => "http"
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@ -1280,6 +1280,30 @@ func TestIgnoreDocumentationPackage(t *testing.T) {
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})
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})
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}
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}
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// Tests importPathToNameGoPathParse and in particular that it stops
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// after finding the first non-documentation package name, not
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// reporting an error on inconsistent package names (since it should
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// never make it that far).
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func TestImportPathToNameGoPathParse(t *testing.T) {
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testConfig{
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gopathFiles: map[string]string{
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"example.net/pkg/doc.go": "package documentation\n", // ignored
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"example.net/pkg/gen.go": "package main\n", // also ignored
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"example.net/pkg/pkg.go": "package the_pkg_name_to_find\n and this syntax error is ignored because of parser.PackageClauseOnly",
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"example.net/pkg/z.go": "package inconsistent\n", // inconsistent but ignored
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},
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}.test(t, func(t *goimportTest) {
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got, err := importPathToNameGoPathParse("example.net/pkg", filepath.Join(t.gopath, "src", "other.net"))
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if err != nil {
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t.Fatal(err)
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}
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const want = "the_pkg_name_to_find"
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if got != want {
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t.Errorf("importPathToNameGoPathParse(..) = %q; want %q", got, want)
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}
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})
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}
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func strSet(ss []string) map[string]bool {
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func strSet(ss []string) map[string]bool {
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m := make(map[string]bool)
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m := make(map[string]bool)
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for _, s := range ss {
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for _, s := range ss {
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