Merge pull request go-sql-driver#195 from arnehormann/faster-dateformat

changed binary date / datetime to string

Author: arnehormann

packets.go

@@ -1056,7 +1056,7 @@ func (rows *binaryRows) readRow(dest []driver.Value) error {
 			if rows.mc.parseTime {
 				dest[i], err = parseBinaryDateTime(num, data[pos:], rows.mc.cfg.loc)
 			} else {
-				dest[i], err = formatBinaryDate(num, data[pos:])
+				dest[i], err = formatBinaryDateTime(data[pos:pos+int(num)], false)
 			}
 
 			if err == nil {
@@ -1124,7 +1124,7 @@ func (rows *binaryRows) readRow(dest []driver.Value) error {
 			if rows.mc.parseTime {
 				dest[i], err = parseBinaryDateTime(num, data[pos:], rows.mc.cfg.loc)
 			} else {
-				dest[i], err = formatBinaryDateTime(num, data[pos:])
+				dest[i], err = formatBinaryDateTime(data[pos:pos+int(num)], true)
 			}
 
 			if err == nil {

utils.go

@@ -503,55 +503,84 @@ func parseBinaryDateTime(num uint64, data []byte, loc *time.Location) (driver.Va
 	return nil, fmt.Errorf("Invalid DATETIME-packet length %d", num)
 }
 
-func formatBinaryDate(num uint64, data []byte) (driver.Value, error) {
-	switch num {
-	case 0:
-		return []byte("0000-00-00"), nil
-	case 4:
-		return []byte(fmt.Sprintf(
-			"%04d-%02d-%02d",
-			binary.LittleEndian.Uint16(data[:2]),
-			data[2],
-			data[3],
-		)), nil
-	}
-	return nil, fmt.Errorf("Invalid DATE-packet length %d", num)
-}
-
-func formatBinaryDateTime(num uint64, data []byte) (driver.Value, error) {
-	switch num {
-	case 0:
-		return []byte("0000-00-00 00:00:00"), nil
-	case 4:
-		return []byte(fmt.Sprintf(
-			"%04d-%02d-%02d 00:00:00",
-			binary.LittleEndian.Uint16(data[:2]),
-			data[2],
-			data[3],
-		)), nil
-	case 7:
-		return []byte(fmt.Sprintf(
-			"%04d-%02d-%02d %02d:%02d:%02d",
-			binary.LittleEndian.Uint16(data[:2]),
-			data[2],
-			data[3],
-			data[4],
-			data[5],
-			data[6],
-		)), nil
-	case 11:
-		return []byte(fmt.Sprintf(
-			"%04d-%02d-%02d %02d:%02d:%02d.%06d",
-			binary.LittleEndian.Uint16(data[:2]),
-			data[2],
-			data[3],
-			data[4],
-			data[5],
-			data[6],
-			binary.LittleEndian.Uint32(data[7:11]),
-		)), nil
+// zeroDateTime is used in formatBinaryDateTime to avoid an allocation
+// if the DATE or DATETIME has the zero value.
+// It must never be changed.
+// The current behavior depends on database/sql copying the result.
+var zeroDateTime = []byte("0000-00-00 00:00:00")
+
+func formatBinaryDateTime(src []byte, withTime bool) (driver.Value, error) {
+	if len(src) == 0 {
+		if withTime {
+			return zeroDateTime, nil
+		}
+		return zeroDateTime[:10], nil
+	}
+	var dst []byte
+	if withTime {
+		if len(src) == 11 {
+			dst = []byte("0000-00-00 00:00:00.000000")
+		} else {
+			dst = []byte("0000-00-00 00:00:00")
+		}
+	} else {
+		dst = []byte("0000-00-00")
 	}
-	return nil, fmt.Errorf("Invalid DATETIME-packet length %d", num)
+	switch len(src) {
+	case 11:
+		microsecs := binary.LittleEndian.Uint32(src[7:11])
+		tmp32 := microsecs / 10
+		dst[25] += byte(microsecs - 10*tmp32)
+		tmp32, microsecs = tmp32/10, tmp32
+		dst[24] += byte(microsecs - 10*tmp32)
+		tmp32, microsecs = tmp32/10, tmp32
+		dst[23] += byte(microsecs - 10*tmp32)
+		tmp32, microsecs = tmp32/10, tmp32
+		dst[22] += byte(microsecs - 10*tmp32)
+		tmp32, microsecs = tmp32/10, tmp32
+		dst[21] += byte(microsecs - 10*tmp32)
+		dst[20] += byte(microsecs / 10)
+		fallthrough
+	case 7:
+		second := src[6]
+		tmp := second / 10
+		dst[18] += second - 10*tmp
+		dst[17] += tmp
+		minute := src[5]
+		tmp = minute / 10
+		dst[15] += minute - 10*tmp
+		dst[14] += tmp
+		hour := src[4]
+		tmp = hour / 10
+		dst[12] += hour - 10*tmp
+		dst[11] += tmp
+		fallthrough
+	case 4:
+		day := src[3]
+		tmp := day / 10
+		dst[9] += day - 10*tmp
+		dst[8] += tmp
+		month := src[2]
+		tmp = month / 10
+		dst[6] += month - 10*tmp
+		dst[5] += tmp
+		year := binary.LittleEndian.Uint16(src[:2])
+		tmp16 := year / 10
+		dst[3] += byte(year - 10*tmp16)
+		tmp16, year = tmp16/10, tmp16
+		dst[2] += byte(year - 10*tmp16)
+		tmp16, year = tmp16/10, tmp16
+		dst[1] += byte(year - 10*tmp16)
+		dst[0] += byte(tmp16)
+		return dst, nil
+	}
+	var t string
+	if withTime {
+		t = "DATETIME"
+	} else {
+		t = "DATE"
+	}
+	return nil, fmt.Errorf("invalid %s-packet length %d", t, len(src))
 }
 
 /******************************************************************************

utils_test.go

@@ -10,6 +10,7 @@ package mysql
 
 import (
 	"bytes"
+	"encoding/binary"
 	"fmt"
 	"testing"
 	"time"
@@ -180,3 +181,32 @@ func TestOldPass(t *testing.T) {
 		}
 	}
 }
+
+func TestFormatBinaryDateTime(t *testing.T) {
+	rawDate := [11]byte{}
+	binary.LittleEndian.PutUint16(rawDate[:2], 1978)   // years
+	rawDate[2] = 12                                    // months
+	rawDate[3] = 30                                    // days
+	rawDate[4] = 15                                    // hours
+	rawDate[5] = 46                                    // minutes
+	rawDate[6] = 23                                    // seconds
+	binary.LittleEndian.PutUint32(rawDate[7:], 987654) // microseconds
+	expect := func(expected string, length int, withTime bool) {
+		actual, _ := formatBinaryDateTime(rawDate[:length], withTime)
+		bytes, ok := actual.([]byte)
+		if !ok {
+			t.Errorf("formatBinaryDateTime must return []byte, was %T", actual)
+		}
+		if string(bytes) != expected {
+			t.Errorf(
+				"expected %q, got %q for length %d, withTime %v",
+				bytes, actual, length, withTime,
+			)
+		}
+	}
+	expect("0000-00-00", 0, false)
+	expect("0000-00-00 00:00:00", 0, true)
+	expect("1978-12-30", 4, false)
+	expect("1978-12-30 15:46:23", 7, true)
+	expect("1978-12-30 15:46:23.987654", 11, true)
+}