Arg enhancements to noms-log.

Added -n arg to limit number of commits that are displayed.
Changed dataspec arg to valuespec arg so that sha1's can be used as starting commit.

clients/go/flags/dataspec.go

@@ -159,6 +159,7 @@ func (spec DatasetSpec) Value() (datas.Database, types.Value, error) {
 
 	commit, ok := dataset.MaybeHead()
 	if !ok {
+		dataset.Database().Close()
 		return nil, nil, fmt.Errorf("No head value for dataset: %s", spec.DatasetName)
 	}
 

clients/go/util/check_error.go

@@ -5,15 +5,34 @@
 package util
 
 import (
-    "flag"
-    "fmt"
-    "os"
+	"flag"
+	"fmt"
+	"os"
 )
 
-func CheckError(err error) {
-    if err != nil {
-        fmt.Fprintf(os.Stderr, "error: %s\n", err)
-        flag.Usage()
-        os.Exit(-1)
-    }
+type Exiter interface {
+	Exit(code int)
+}
+
+type nomsExiter struct{}
+
+func (e nomsExiter) Exit(code int) {
+	os.Exit(code)
+}
+
+var UtilExiter Exiter = nomsExiter{}
+
+func CheckError(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %s\n", err)
+		flag.Usage()
+		UtilExiter.Exit(-1)
+	}
+}
+
+func CheckErrorNoUsage(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error: %s\n", err)
+		UtilExiter.Exit(-1)
+	}
 }

cmd/noms-log/noms_log.go

@@ -9,6 +9,7 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"math"
 	"os"
 	"strings"
 
@@ -23,6 +24,7 @@ import (
 var (
 	color         = flag.Int("color", -1, "value of 1 forces color on, 2 forces color off")
 	maxLines      = flag.Int("max-lines", 10, "max number of lines to show per commit (-1 for all lines)")
+	maxCommits    = flag.Int("n", 0, "max number of commits to display (0 for all commits)")
 	showHelp      = flag.Bool("help", false, "show help text")
 	showGraph     = flag.Bool("graph", false, "show ascii-based commit hierarcy on left side of output")
 	stdoutIsTty   = flag.Int("stdout-is-tty", -1, "value of 1 forces tty ouput, 0 forces non-tty output (provided for use by other programs)")
@@ -33,7 +35,8 @@ var (
 func main() {
 	flag.Usage = func() {
 		fmt.Fprintln(os.Stderr, "Displays the history of a Noms dataset\n")
-		fmt.Fprintln(os.Stderr, "Usage: noms log <dataset>")
+		fmt.Fprintln(os.Stderr, "Usage: noms log <commitObject>")
+		fmt.Fprintln(os.Stderr, "commitObject must be a dataset or object spec that refers to a commit.")
 		flag.PrintDefaults()
 		fmt.Fprintf(os.Stderr, "\nSee \"Spelling Objects\" at https://github.com/attic-labs/noms/blob/master/doc/spelling.md for details on the object argument.\n\n")
 	}
@@ -50,23 +53,31 @@ func main() {
 
 	useColor = shouldUseColor()
 
-	spec, err := flags.ParseDatasetSpec(flag.Arg(0))
-	util.CheckError(err)
-	dataset, err := spec.Dataset()
+	spec, err := flags.ParsePathSpec(flag.Arg(0))
 	util.CheckError(err)
+	database, value, err := spec.Value()
+	if err != nil {
+		util.CheckErrorNoUsage(err)
+	}
+	defer database.Close()
 
-	origCommit, ok := dataset.MaybeHead()
-
-	if ok {
-		iter := NewCommitIterator(dataset.Database(), origCommit)
-		for ln, ok := iter.Next(); ok; ln, ok = iter.Next() {
-			if printCommit(ln) != nil {
-				break
-			}
-		}
+	origCommit, ok := value.(types.Struct)
+	if !ok || !origCommit.Type().Equals(datas.CommitType()) {
+		util.CheckError(fmt.Errorf("%s does not reference a Commit object", spec))
+	}
+
+	iter := NewCommitIterator(database, origCommit)
+	displayed := 0
+	if *maxCommits <= 0 {
+		*maxCommits = math.MaxInt32
+	}
+	for ln, ok := iter.Next(); ok && displayed < *maxCommits; ln, ok = iter.Next() {
+		if printCommit(ln) != nil {
+			break
+		}
+		displayed++
 	}
 
-	dataset.Database().Close()
 }
 
 // Prints the information for one commit in the log, including ascii graph on left side of commits if

cmd/noms-log/noms_log_test.go

@@ -10,13 +10,28 @@ import (
 
 	"github.com/attic-labs/noms/clients/go/flags"
 	"github.com/attic-labs/noms/clients/go/test_util"
+	"github.com/attic-labs/noms/clients/go/util"
 	"github.com/attic-labs/noms/dataset"
 	"github.com/attic-labs/noms/types"
 	"github.com/attic-labs/testify/assert"
 	"github.com/attic-labs/testify/suite"
 )
 
+type testExiter struct{}
+type exitError struct {
+	code int
+}
+
+func (e exitError) Error() string {
+	return fmt.Sprintf("Exiting with code: %d", e.code)
+}
+
+func (testExiter) Exit(code int) {
+	panic(exitError{code})
+}
+
 func TestNomsShow(t *testing.T) {
+	util.UtilExiter = testExiter{}
 	suite.Run(t, &nomsShowTestSuite{})
 }
 
@@ -29,7 +44,7 @@ func testCommitInResults(s *nomsShowTestSuite, spec string, i int) {
 	s.NoError(err)
 	ds, err := sp.Dataset()
 	s.NoError(err)
-	ds, err = ds.Commit(types.Number(1))
+	ds, err = ds.Commit(types.Number(i))
 	s.NoError(err)
 	commit := ds.Head()
 	fmt.Printf("commit hash: %s, type: %s\n", commit.Hash(), commit.Type().Name())
@@ -46,7 +61,7 @@ func (s *nomsShowTestSuite) TestNomsLog() {
 	ds, err := sp.Dataset()
 	s.NoError(err)
 	ds.Database().Close()
-	s.Equal("", s.Run(main, []string{spec}))
+	s.Panics(func() { s.Run(main, []string{spec}) })
 
 	testCommitInResults(s, spec, 1)
 	testCommitInResults(s, spec, 2)
@@ -68,6 +83,42 @@ func mergeDatasets(ds1, ds2 dataset.Dataset, v string) (dataset.Dataset, error)
 	return ds1.CommitWithParents(types.NewString(v), types.NewSet(ds1.HeadRef(), ds2.HeadRef()))
 }
 
+func (s *nomsShowTestSuite) TestNArg() {
+	spec := fmt.Sprintf("ldb:%s", s.LdbDir)
+	dsName := "nArgTest"
+	dbSpec, err := flags.ParseDatabaseSpec(spec)
+	s.NoError(err)
+	db, err := dbSpec.Database()
+	s.NoError(err)
+
+	ds := dataset.NewDataset(db, dsName)
+
+	ds, err = addCommit(ds, "1")
+	h1 := ds.Head().Hash()
+	s.NoError(err)
+	ds, err = addCommit(ds, "2")
+	s.NoError(err)
+	h2 := ds.Head().Hash()
+	ds, err = addCommit(ds, "3")
+	s.NoError(err)
+	h3 := ds.Head().Hash()
+	db.Close()
+
+	dsSpec := fmt.Sprintf("ldb:%s:%s", s.LdbDir, dsName)
+	s.NotContains(s.Run(main, []string{"-n=1", dsSpec}), h1.String())
+	res := s.Run(main, []string{"-n=0", dsSpec})
+	s.Contains(res, h3.String())
+	s.Contains(res, h2.String())
+	s.Contains(res, h1.String())
+
+	vSpec := fmt.Sprintf("ldb:%s:%s", s.LdbDir, h3)
+	s.NotContains(s.Run(main, []string{"-n=1", vSpec}), h1.String())
+	res = s.Run(main, []string{"-n=0", vSpec})
+	s.Contains(res, h3.String())
+	s.Contains(res, h2.String())
+	s.Contains(res, h1.String())
+}
+
 func (s *nomsShowTestSuite) TestNomsGraph1() {
 	spec := fmt.Sprintf("ldb:%s", s.LdbDir)
 	dbSpec, err := flags.ParseDatabaseSpec(spec)

datas/commit.go

@@ -49,3 +49,7 @@ func NewMapOfStringToRefOfCommit() types.Map {
 func typeForSetOfRefOfCommit() *types.Type {
 	return types.MakeSetType(types.MakeRefType(commitType))
 }
+
+func CommitType() *types.Type {
+	return commitType
+}