time: implement faster and simpler push_http_header (#26155)

Author: enghitalo

vlib/builtin/js/array.js.v

@@ -414,6 +414,11 @@ pub fn (a array) to_number_array() JS.Array {
 	return tmp
 }
 
+// push_many - appends multiple values to the end of the array.
+pub fn (mut a array) push_many(val voidptr, size int) {
+	a.insert_many(a.len, val, size)
+}
+
 type EveryFn = fn (JS.Number, JS.Number) JS.Boolean
 
 type BigEveryFn = fn (JS.BigInt, JS.Number) JS.Boolean

vlib/time/format.v

@@ -35,6 +35,28 @@ fn int_to_byte_array_no_pad(value int, mut arr []u8, size int) {
 	}
 }
 
+// int_to_byte_array_no_pad fulfill buffer by part
+// it doesn't pad with leading zeros for performance reasons
+@[direct_array_access; unsafe]
+fn int_to_ptr_byte_array_no_pad(value int, arr_prt &u8, arr_len int) {
+	mut num := value
+	if arr_len <= 0 || num < 0 {
+		return
+	}
+
+	// Start from the end of the array
+	mut i := arr_len - 1
+
+	// Convert each digit to a character and store it in the array
+	for num > 0 && i >= 0 {
+		unsafe {
+			*(arr_prt + i) = (num % 10) + `0`
+		}
+		num /= 10
+		i--
+	}
+}
+
 // format returns a date string in "YYYY-MM-DD HH:mm" format (24h).
 @[manualfree]
 pub fn (t Time) format() string {
@@ -698,26 +720,31 @@ pub fn (t Time) utc_string() string {
 // e.g. "Sun, 06 Nov 1994 08:49:37 GMT"
 @[manualfree]
 pub fn (t Time) http_header_string() string {
+	mut buf := []u8{cap: 29}
+	t.push_to_http_header(mut buf)
+
+	return buf.bytestr()
+}
+
+// push_to_http_header returns a date string in the format used in HTTP headers, as defined in RFC 2616.
+// e.g. "Sun, 06 Nov 1994 08:49:37 GMT"
+pub fn (t Time) push_to_http_header(mut buffer []u8) {
 	day_str := t.weekday_str()
 	month_str := t.smonth()
 
 	mut buf := [day_str[0], day_str[1], day_str[2], `,`, ` `, `0`, `0`, ` `, month_str[0], month_str[1],
 		month_str[2], ` `, `0`, `0`, `0`, `0`, ` `, `0`, `0`, `:`, `0`, `0`, `:`, `0`, `0`, ` `,
-		`G`, `M`, `T`]
-
-	defer {
-		unsafe { buf.free() }
+		`G`, `M`, `T`]!
+	unsafe {
+		int_to_ptr_byte_array_no_pad(t.day, &buf[5], 2)
+		int_to_ptr_byte_array_no_pad(t.year, &buf[12], 4)
+		int_to_ptr_byte_array_no_pad(t.hour, &buf[17], 2)
+		int_to_ptr_byte_array_no_pad(t.minute, &buf[20], 2)
+		int_to_ptr_byte_array_no_pad(t.second, &buf[23], 2)
+	}
+	unsafe {
+		buffer.push_many(&buf[0], buf.len)
 	}
-
-	int_to_byte_array_no_pad(t.day, mut buf, 7)
-	int_to_byte_array_no_pad(t.year, mut buf, 16)
-	int_to_byte_array_no_pad(t.hour, mut buf, 19)
-	int_to_byte_array_no_pad(t.minute, mut buf, 22)
-	int_to_byte_array_no_pad(t.second, mut buf, 25)
-
-	http_header_string := buf.bytestr()
-
-	return http_header_string
 }
 
 // mceil returns the least integer value greater than or equal to x.

vlib/time/time_format_test.v

@@ -89,3 +89,10 @@ fn test_utc_string() {
 fn test_http_header_string() {
 	assert 'Fri, 11 Jul 1980 21:23:42 GMT' == time_to_test.http_header_string()
 }
+
+fn test_push_to_http_header() {
+	mut http1_1_buffer := 'HTTP/1.1 200 OK\r\nDate: '.bytes()
+	time_to_test.push_to_http_header(mut http1_1_buffer)
+
+	assert http1_1_buffer.bytestr() == 'HTTP/1.1 200 OK\r\nDate: Fri, 11 Jul 1980 21:23:42 GMT'
+}