Add standard time format (#52)

Author: benbjohnson

ltx.go

@@ -12,6 +12,7 @@ import (
 	"io"
 	"regexp"
 	"strconv"
+	"time"
 )
 
 const (
@@ -29,6 +30,10 @@ const (
 	TrailerSize    = 16
 )
 
+// RFC3339Milli is the standard time format for LTX timestamps.
+// It uses fixed-width millisecond resolution which makes it sortable.
+const RFC3339Milli = "2006-01-02T15:04:05.000Z07:00"
+
 // Checksum size & positions.
 const (
 	ChecksumSize          = 8
@@ -499,6 +504,29 @@ func ParseFilename(name string) (minTXID, maxTXID TXID, err error) {
 	return TXID(min), TXID(max), nil
 }
 
+// FormatTimestamp returns t with a fixed-width, millisecond-resolution UTC format.
+func FormatTimestamp(t time.Time) string {
+	return t.UTC().Format(RFC3339Milli)
+}
+
+// ParseTimestamp parses a timestamp as RFC3339Milli (fixed-width) but will
+// fallback to RFC3339Nano if it fails. This is to support timestamps written
+// before the introduction of the standard time format.
+func ParseTimestamp(value string) (time.Time, error) {
+	// Attempt standard format first.
+	t, err := time.Parse(RFC3339Milli, value)
+	if err == nil {
+		return t, nil
+	}
+
+	// If the standard fails, fallback to stdlib format but truncate to milliseconds.
+	t2, err2 := time.Parse(time.RFC3339Nano, value)
+	if err2 != nil {
+		return t, err // use original error on failure.
+	}
+	return t2.Truncate(time.Millisecond), nil
+}
+
 var filenameRegex = regexp.MustCompile(`^([0-9a-f]{16})-([0-9a-f]{16})\.ltx$`)
 
 // FormatFilename returns an LTX filename representing a range of transactions.

ltx_test.go

@@ -11,6 +11,7 @@ import (
 	"os"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/superfly/ltx"
 )
@@ -530,6 +531,44 @@ func TestParseTXID(t *testing.T) {
 	})
 }
 
+func TestFormatTimestamp(t *testing.T) {
+	for _, tt := range []struct {
+		t    time.Time
+		want string
+	}{
+		{time.Date(2000, 10, 20, 30, 40, 50, 0, time.UTC), "2000-10-21T06:40:50.000Z"},
+		{time.Date(2000, 10, 20, 30, 40, 50, 123000000, time.UTC), "2000-10-21T06:40:50.123Z"},
+		{time.Date(2000, 10, 20, 30, 40, 50, 120000000, time.UTC), "2000-10-21T06:40:50.120Z"},
+		{time.Date(2000, 10, 20, 30, 40, 50, 100000000, time.UTC), "2000-10-21T06:40:50.100Z"},
+		{time.Date(2000, 10, 20, 30, 40, 50, 100000, time.UTC), "2000-10-21T06:40:50.000Z"}, // submillisecond
+	} {
+		if got := ltx.FormatTimestamp(tt.t); got != tt.want {
+			t.Fatalf("got=%s, want %s", got, tt.want)
+		}
+	}
+}
+
+func TestParseTimestamp(t *testing.T) {
+	for _, tt := range []struct {
+		str  string
+		want time.Time
+	}{
+		{"2000-10-21T06:40:50.000Z", time.Date(2000, 10, 20, 30, 40, 50, 0, time.UTC)},
+		{"2000-10-21T06:40:50.123Z", time.Date(2000, 10, 20, 30, 40, 50, 123000000, time.UTC)},
+		{"2000-10-21T06:40:50.120Z", time.Date(2000, 10, 20, 30, 40, 50, 120000000, time.UTC)},
+		{"2000-10-21T06:40:50.100Z", time.Date(2000, 10, 20, 30, 40, 50, 100000000, time.UTC)},
+		{"2000-10-21T06:40:50Z", time.Date(2000, 10, 20, 30, 40, 50, 0, time.UTC)},
+		{"2000-10-21T06:40:50.000123Z", time.Date(2000, 10, 20, 30, 40, 50, 0, time.UTC)},
+		{"2000-10-21T06:40:50.000000123Z", time.Date(2000, 10, 20, 30, 40, 50, 0, time.UTC)},
+	} {
+		if got, err := ltx.ParseTimestamp(tt.str); err != nil {
+			t.Fatal(err)
+		} else if !got.Equal(tt.want) {
+			t.Fatalf("got=%s, want %s", got, tt.want)
+		}
+	}
+}
+
 func BenchmarkChecksumPage(b *testing.B) {
 	for _, pageSize := range []int{512, 1024, 2048, 4096, 8192, 16384, 32768, 65536} {
 		b.Run(fmt.Sprint(pageSize), func(b *testing.B) {