From bbcd7a7e3daec0d035603601d085623fa97180cb Mon Sep 17 00:00:00 2001
From: Nikolay Sivko <n.sivko@gmail.com>
Date: Mon, 30 Oct 2023 15:05:14 +0300
Subject: [PATCH] optimize timestamp detection

---
 timestamp.go      | 40 ++++++++++++++++++----------------------
 timestamp_test.go | 33 ++++++++++++++++++++++++++-------
 2 files changed, 44 insertions(+), 29 deletions(-)

diff --git a/timestamp.go b/timestamp.go
index 4a382cd..df26bd3 100644
--- a/timestamp.go
+++ b/timestamp.go
@@ -1,35 +1,31 @@
 package logparser
 
-import (
-	"regexp"
-)
-
 const (
 	lookForTimestampLimit = 100
 )
 
-var (
-	timestampRegexes = []*regexp.Regexp{
-		regexp.MustCompile(`(^|\s)\d{2}:\d{2}(:\d{2}[^\s"']*)?`),
-		regexp.MustCompile(`\d{2} [A-Z][a-z]{2} \d{4}`),
-		regexp.MustCompile(`\d{4}-\d{2}-\d{2}`),
-		regexp.MustCompile(`\d{4}/\d{2}/\d{2}`),
-		regexp.MustCompile(`\d{4}\.\d{2}\.\d{2}`),
-		regexp.MustCompile(`[A-Z][a-z]{2} \d{2}`),
-		regexp.MustCompile(`\d{2}-\d{2}-\d{4}`),
-		regexp.MustCompile(`\d{2}/\d{2}/\d{4}`),
-		regexp.MustCompile(`\d{2}\.\d{2}\.\d{4}`),
-		regexp.MustCompile(`\d{2}/[A-Z][a-z]{2}/\d{4}`),
-	}
-)
-
 func containsTimestamp(line string) bool {
 	if len(line) > lookForTimestampLimit {
 		line = line[:lookForTimestampLimit]
 	}
-	for _, re := range timestampRegexes {
-		if re.MatchString(line) {
-			return true
+	var digits, colons int
+	for _, r := range line {
+		switch {
+		case r >= '0' && r <= '9':
+			digits++
+			if digits > 2 {
+				digits = 0
+			}
+			if digits == 2 && colons == 2 {
+				return true
+			}
+		case r == ':':
+			if digits == 2 {
+				colons++
+			}
+			digits = 0
+		default:
+			digits, colons = 0, 0
 		}
 	}
 	return false
diff --git a/timestamp_test.go b/timestamp_test.go
index 6e936eb..83d11d3 100644
--- a/timestamp_test.go
+++ b/timestamp_test.go
@@ -3,16 +3,10 @@ package logparser
 import (
 	"github.com/stretchr/testify/assert"
 	"testing"
+	"time"
 )
 
 func Test_containsTimestamp(t *testing.T) {
-	assert.True(t, containsTimestamp("2005-08-09"))
-	assert.True(t, containsTimestamp("2020/06/26"))
-	assert.True(t, containsTimestamp("02/17/2009"))
-	assert.True(t, containsTimestamp("25.02.2013"))
-	assert.True(t, containsTimestamp("2013.25.02"))
-	assert.True(t, containsTimestamp("18:31"))
-	assert.True(t, containsTimestamp("18:31:42"))
 	assert.True(t, containsTimestamp("18:31:42+03"))
 	assert.True(t, containsTimestamp("18:31:42-03"))
 	assert.True(t, containsTimestamp("18:31:42+03:30"))
@@ -25,4 +19,29 @@ func Test_containsTimestamp(t *testing.T) {
 	assert.True(t, containsTimestamp("2005-08-09T18:31:42"))
 	assert.True(t, containsTimestamp("2005-08-09T18:31:42.201"))
 	assert.True(t, containsTimestamp(`10/Oct/2000:13:55:36 -0700`))
+	assert.True(t, containsTimestamp(time.ANSIC))
+	assert.True(t, containsTimestamp(time.UnixDate))
+	assert.True(t, containsTimestamp(time.RubyDate))
+	assert.True(t, containsTimestamp(time.RFC850))
+	assert.True(t, containsTimestamp(time.RFC1123))
+	assert.True(t, containsTimestamp(time.RFC1123Z))
+	assert.True(t, containsTimestamp(time.RFC3339))
+	assert.True(t, containsTimestamp(time.RFC3339Nano))
+	assert.True(t, containsTimestamp(time.Stamp))
+	assert.True(t, containsTimestamp(time.StampMilli))
+	assert.True(t, containsTimestamp(time.StampMicro))
+
+	assert.False(t, containsTimestamp("13/32"))
+	assert.False(t, containsTimestamp("13:32"))
+	assert.False(t, containsTimestamp("100/5/100"))
+	assert.False(t, containsTimestamp("1:12:123"))
+	assert.False(t, containsTimestamp("12:aa:12:32"))
+
+}
+
+func Benchmark_containsTimestamp(b *testing.B) {
+	l := `10.42.0.21 - - [30/Oct/2023:11:55:47 +0000] "GET / HTTP/1.1" 200 612 "-" "-" "-"`
+	for n := 0; n < b.N; n++ {
+		containsTimestamp(l)
+	}
 }