cmd/api: eliminate duplicate package import work

On my Mac, cuts the API checks from 15 seconds to 6 seconds.
Also clean up some tag confusion: go run list-of-files ignores tags.

R=bradfitz, gri
CC=golang-dev
https://golang.org/cl/12699048

diff --git a/src/cmd/api/goapi.go b/src/cmd/api/goapi.go
index 1b28628016474096dd28915c20636997a1dc0905..1138f4db02f0a5492ff179e9f7a1589e322a9931 100644 (file)
--- a/src/cmd/api/goapi.go
+++ b/src/cmd/api/goapi.go
@@ -1,9 +1,9 @@
-// +build api_tool
-
 // Copyright 2011 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 api_tool
+
 // Binary api computes the exported API of a set of Go packages.
 package main
 
@@ -387,6 +387,38 @@ func contains(list []string, s string) bool {
        return false
 }
 
+var (
+       pkgCache = map[string]*types.Package{} // map tagKey to package
+       pkgTags  = map[string][]string{}       // map import dir to list of relevant tags
+)
+
+// tagKey returns the tag-based key to use in the pkgCache.
+// It is a comma-separated string; the first part is dir, the rest tags.
+// The satisfied tags are derived from context but only those that
+// matter (the ones listed in the tags argument) are used.
+// The tags list, which came from go/build's Package.AllTags,
+// is known to be sorted.
+func tagKey(dir string, context *build.Context, tags []string) string {
+       ctags := map[string]bool{
+               context.GOOS:   true,
+               context.GOARCH: true,
+       }
+       if context.CgoEnabled {
+               ctags["cgo"] = true
+       }
+       for _, tag := range context.BuildTags {
+               ctags[tag] = true
+       }
+       // TODO: ReleaseTags (need to load default)
+       key := dir
+       for _, tag := range tags {
+               if ctags[tag] {
+                       key += "," + tag
+               }
+       }
+       return key
+}
+
 // Importing is a sentinel taking the place in Walker.imported
 // for a package that is in the process of being imported.
 var importing types.Package
@@ -411,6 +443,19 @@ func (w *Walker) Import(name string) (pkg *types.Package) {
        if context == nil {
                context = &build.Default
        }
+
+       // Look in cache.
+       // If we've already done an import with the same set
+       // of relevant tags, reuse the result.
+       var key string
+       if tags, ok := pkgTags[dir]; ok {
+               key = tagKey(dir, context, tags)
+               if pkg := pkgCache[key]; pkg != nil {
+                       w.imported[name] = pkg
+                       return pkg
+               }
+       }
+
        info, err := context.ImportDir(dir, 0)
        if err != nil {
                if _, nogo := err.(*build.NoGoError); nogo {
@@ -418,6 +463,13 @@ func (w *Walker) Import(name string) (pkg *types.Package) {
                }
                log.Fatalf("pkg %q, dir %q: ScanDir: %v", name, dir, err)
        }
+
+       // Save tags list first time we see a directory.
+       if _, ok := pkgTags[dir]; !ok {
+               pkgTags[dir] = info.AllTags
+               key = tagKey(dir, context, info.AllTags)
+       }
+
        filenames := append(append([]string{}, info.GoFiles...), info.CgoFiles...)
 
        // Certain files only exist when building for the specified context.
@@ -463,6 +515,8 @@ func (w *Walker) Import(name string) (pkg *types.Package) {
                log.Fatalf("error typechecking package %s: %s (%s)", name, err, ctxt)
        }
 
+       pkgCache[key] = pkg
+
        w.imported[name] = pkg
        return
 }

diff --git a/src/cmd/api/run.go b/src/cmd/api/run.go
index 6e89bb7346e4c3f9e5b3092d9203baf1555e3eaa..520c56fd526ae0b50170ca7729ac365a3f338612 100644 (file)
--- a/src/cmd/api/run.go
+++ b/src/cmd/api/run.go
@@ -1,9 +1,9 @@
-// +build from_src_run
-
 // Copyright 2013 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 ignore
+
 // The run program is invoked via "go run" from src/run.bash or
 // src/run.bat conditionally builds and runs the cmd/api tool.
 //

diff --git a/src/run.bash b/src/run.bash
index 178290327a7e1bc027a0ce6e4f07532ef81d6849..258a4d2f94f318babedfe65d4f67c779a75278d2 100755 (executable)
--- a/src/run.bash
+++ b/src/run.bash
@@ -182,7 +182,7 @@ time go run run.go || exit 1
 
 echo
 echo '# Checking API compatibility.'
-go run --tags=from_src_run $GOROOT/src/cmd/api/run.go
+time go run $GOROOT/src/cmd/api/run.go
 
 echo
 echo ALL TESTS PASSED

diff --git a/src/run.bat b/src/run.bat
index 36f594bb879ad015647c2fc19194fade5074f7f8..bf038d1a767873c60bc96b00e28cd55b15470d8d 100644 (file)
--- a/src/run.bat
+++ b/src/run.bat
@@ -121,7 +121,7 @@ set GOMAXPROCS=%OLDGOMAXPROCS%
 set OLDGOMAXPROCS=
 
 echo # Checking API compatibility.
-go run --tags=from_src_run "%GOROOT%\src\cmd\api\run.go"
+go run "%GOROOT%\src\cmd\api\run.go"
 if errorlevel 1 goto fail
 echo.