goinstall: select the tag that is closest to runtime.Version

release.r50 looks for newest tag <= go.r50
weekly.2010-10-10 looks for newest tag <= go.2010-10-10

Implements behavior for hg, git, and bzr.

R=dsymonds, rsc, n13m3y3r
CC=golang-dev
https://golang.org/cl/4873057

src/cmd/goinstall/Makefile

@@ -11,3 +11,9 @@ GOFILES=\
 	make.go\
 
 include ../../Make.cmd
+
+test:
+	gotest
+
+testshort:
+	gotest -test.short

src/cmd/goinstall/doc.go

@@ -94,8 +94,11 @@ attempt to fetch updates.  The -u flag changes this behavior,
 causing goinstall to update all remote packages encountered during
 the installation.
 
-When downloading or updating, goinstall first looks for a tag or branch
-named "release".  If there is one, it uses that version of the code.
+When downloading or updating, goinstall looks for a tag with the "go." prefix
+that corresponds to the local Go version. For Go "release.r58" it looks for a
+tag named "go.r58". For "weekly.2011-06-03" it looks for "go.weekly.2011-06-03".
+If the specific "go.X" tag is not found, it chooses the closest earlier version.
+If an appropriate tag is found, goinstall uses that version of the code.
 Otherwise it uses the default version selected by the version control
 system, typically HEAD for git, tip for Mercurial.
 

src/cmd/goinstall/download.go

@@ -7,12 +7,15 @@
 package main
 
 import (
+	"bytes"
 	"exec"
 	"fmt"
 	"http"
 	"os"
 	"path/filepath"
 	"regexp"
+	"runtime"
+	"strconv"
 	"strings"
 )
 
@@ -42,12 +45,11 @@ type vcs struct {
 	checkout      string
 	clone         string
 	update        string
-	updateReleaseFlag string
+	updateRevFlag string
 	pull          string
 	pullForceFlag string
-	log               string
-	logLimitFlag      string
-	logReleaseFlag    string
+	tagList       string
+	tagListRe     *regexp.Regexp
 	check         string
 	protocols     []string
 	suffix        string
@@ -67,11 +69,9 @@ var hg = vcs{
 	checkout:  "checkout",
 	clone:     "clone",
 	update:    "update",
-	updateReleaseFlag: "release",
 	pull:      "pull",
-	log:               "log",
-	logLimitFlag:      "-l1",
-	logReleaseFlag:    "-rrelease",
+	tagList:   "tags",
+	tagListRe: regexp.MustCompile("([^ ]+)[^\n]+\n"),
 	check:     "identify",
 	protocols: []string{"https", "http"},
 	suffix:    ".hg",
@@ -88,11 +88,9 @@ var git = vcs{
 	checkout:  "checkout",
 	clone:     "clone",
 	update:    "pull",
-	updateReleaseFlag: "release",
 	pull:      "fetch",
-	log:               "show-ref",
-	logLimitFlag:      "",
-	logReleaseFlag:    "release",
+	tagList:   "tag",
+	tagListRe: regexp.MustCompile("([^\n]+)\n"),
 	check:     "ls-remote",
 	protocols: []string{"git", "https", "http"},
 	suffix:    ".git",
@@ -109,10 +107,6 @@ var svn = vcs{
 	checkout:  "checkout",
 	clone:     "checkout",
 	update:    "update",
-	updateReleaseFlag: "release",
-	log:               "log",
-	logLimitFlag:      "-l1",
-	logReleaseFlag:    "release",
 	check:     "info",
 	protocols: []string{"https", "http", "svn"},
 	suffix:    ".svn",
@@ -128,12 +122,11 @@ var bzr = vcs{
 	checkout:      "update",
 	clone:         "branch",
 	update:        "update",
-	updateReleaseFlag: "-rrelease",
+	updateRevFlag: "-r",
 	pull:          "pull",
 	pullForceFlag: "--overwrite",
-	log:               "log",
-	logLimitFlag:      "-l1",
-	logReleaseFlag:    "-rrelease",
+	tagList:       "tags",
+	tagListRe:     regexp.MustCompile("([^ ]+)[^\n]+\n"),
 	check:         "info",
 	protocols:     []string{"https", "http", "bzr"},
 	suffix:        ".bzr",
@@ -240,20 +233,84 @@ func download(pkg, srcDir string) (public bool, err os.Error) {
 	return
 }
 
-// Try to detect if a "release" tag exists.  If it does, update
-// to the tagged version, otherwise just update the current branch.
-// NOTE(_nil): svn will always fail because it is trying to get
-// the revision history of a file named "release" instead of
-// looking for a commit with a release tag
+// updateRepo gets a list of tags in the repository and
+// checks out the tag closest to the current runtime.Version.
+// If no matching tag is found, it just updates to tip.
 func (v *vcs) updateRepo(dst string) os.Error {
-	if err := quietRun(dst, nil, v.cmd, v.log, v.logLimitFlag, v.logReleaseFlag); err == nil {
-		if err := run(dst, nil, v.cmd, v.checkout, v.updateReleaseFlag); err != nil {
-			return err
+	if v.tagList == "" || v.tagListRe == nil {
+		// TODO(adg): fix for svn
+		return run(dst, nil, v.cmd, v.update)
 	}
-	} else if err := run(dst, nil, v.cmd, v.update); err != nil {
+
+	// Get tag list.
+	stderr := new(bytes.Buffer)
+	cmd := exec.Command(v.cmd, v.tagList)
+	cmd.Dir = dst
+	cmd.Stderr = stderr
+	b, err := cmd.Output()
+	if err != nil {
+		errorf("%s %s: %s\n", v.cmd, v.tagList, stderr)
 		return err
 	}
-	return nil
+	var tags []string
+	for _, m := range v.tagListRe.FindAllStringSubmatch(string(b), -1) {
+		tags = append(tags, m[1])
+	}
+
+	// Only use the tag component of runtime.Version.
+	ver := strings.Split(runtime.Version(), " ")[0]
+
+	// Select tag.
+	if tag := selectTag(ver, tags); tag != "" {
+		printf("selecting revision %q\n", tag)
+		return run(dst, nil, v.cmd, v.checkout, v.updateRevFlag+tag)
+	}
+
+	// No matching tag found, make default selection.
+	printf("selecting tip\n")
+	return run(dst, nil, v.cmd, v.update)
+}
+
+// selectTag returns the closest matching tag for a given version.
+// Closest means the latest one that is not after the current release.
+// Version "release.rN" matches tags of the form "go.rN" (N being a decimal).
+// Version "weekly.YYYY-MM-DD" matches tags like "go.weekly.YYYY-MM-DD".
+func selectTag(goVersion string, tags []string) (match string) {
+	const rPrefix = "release.r"
+	if strings.HasPrefix(goVersion, rPrefix) {
+		p := "go.r"
+		v, err := strconv.Atof64(goVersion[len(rPrefix):])
+		if err != nil {
+			return ""
+		}
+		var matchf float64
+		for _, t := range tags {
+			if !strings.HasPrefix(t, p) {
+				continue
+			}
+			tf, err := strconv.Atof64(t[len(p):])
+			if err != nil {
+				continue
+			}
+			if matchf < tf && tf <= v {
+				match, matchf = t, tf
+			}
+		}
+	}
+	const wPrefix = "weekly."
+	if strings.HasPrefix(goVersion, wPrefix) {
+		p := "go.weekly."
+		v := goVersion[len(wPrefix):]
+		for _, t := range tags {
+			if !strings.HasPrefix(t, p) {
+				continue
+			}
+			if match < t && t[len(p):] <= v {
+				match = t
+			}
+		}
+	}
+	return match
 }
 
 // checkoutRepo checks out repo into dst using vcs.

src/cmd/goinstall/tag_test.go

+// 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.
+
+package main
+
+import "testing"
+
+var selectTagTestTags = []string{
+	"go.r58",
+	"go.r58.1",
+	"go.r59",
+	"go.r59.1",
+	"go.r61",
+	"go.r61.1",
+	"go.weekly.2010-01-02",
+	"go.weekly.2011-10-12",
+	"go.weekly.2011-10-12.1",
+	"go.weekly.2011-10-14",
+	"go.weekly.2011-11-01",
+	// these should be ignored:
+	"release.r59",
+	"release.r59.1",
+	"release",
+	"weekly.2011-10-12",
+	"weekly.2011-10-12.1",
+	"weekly",
+	"foo",
+	"bar",
+	"go.f00",
+	"go!r60",
+	"go.1999-01-01",
+}
+
+var selectTagTests = []struct {
+	version  string
+	selected string
+}{
+	{"release.r57", ""},
+	{"release.r58.2", "go.r58.1"},
+	{"release.r59", "go.r59"},
+	{"release.r59.1", "go.r59.1"},
+	{"release.r60", "go.r59.1"},
+	{"release.r60.1", "go.r59.1"},
+	{"release.r61", "go.r61"},
+	{"release.r66", "go.r61.1"},
+	{"weekly.2010-01-01", ""},
+	{"weekly.2010-01-02", "go.weekly.2010-01-02"},
+	{"weekly.2010-01-02.1", "go.weekly.2010-01-02"},
+	{"weekly.2010-01-03", "go.weekly.2010-01-02"},
+	{"weekly.2011-10-12", "go.weekly.2011-10-12"},
+	{"weekly.2011-10-12.1", "go.weekly.2011-10-12.1"},
+	{"weekly.2011-10-13", "go.weekly.2011-10-12.1"},
+	{"weekly.2011-10-14", "go.weekly.2011-10-14"},
+	{"weekly.2011-10-14.1", "go.weekly.2011-10-14"},
+	{"weekly.2011-11-01", "go.weekly.2011-11-01"},
+	{"weekly.2014-01-01", "go.weekly.2011-11-01"},
+	{"weekly.3000-01-01", "go.weekly.2011-11-01"},
+	// faulty versions:
+	{"release.f00", ""},
+	{"weekly.1999-01-01", ""},
+	{"junk", ""},
+	{"", ""},
+}
+
+func TestSelectTag(t *testing.T) {
+	for _, c := range selectTagTests {
+		selected := selectTag(c.version, selectTagTestTags)
+		if selected != c.selected {
+			t.Errorf("selectTag(%q) = %q, want %q", c.version, selected, c.selected)
+		}
+	}
+}

src/pkg/Makefile

@@ -218,7 +218,6 @@ NOTEST+=\
 	../cmd/cgo\
 	../cmd/ebnflint\
 	../cmd/godoc\
-	../cmd/goinstall\
 	../cmd/gotest\
 	../cmd/goyacc\
 	../cmd/hgpatch\