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Use math/bits OnesCount to preallocate slices #995

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Merged
merged 4 commits into from
Feb 22, 2025
Merged

Use math/bits OnesCount to preallocate slices #995

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fda5018
Use math/bits OnesCount to preallocate slices
serprex Feb 20, 2025
afa234b
trailing zeroes to scan flags
serprex Feb 21, 2025
aa908a4
avoid epilogue loop
serprex Feb 21, 2025
91ef5bb
Merge branch 'master' into math-bits
lance6716 Feb 22, 2025
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19 changes: 7 additions & 12 deletions client/conn.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import (
"context"
"crypto/tls"
"fmt"
"math/bits"
"net"
"runtime"
"runtime/debug"
Expand Down Expand Up @@ -557,13 +558,10 @@ func (c *Conn) execSend(query string) error {
// separated by "|". Examples of capability names are CLIENT_DEPRECATE_EOF and CLIENT_PROTOCOL_41.
// These are defined as constants in the mysql package.
func (c *Conn) CapabilityString() string {
var caps []string
capability := c.capability
for i := 0; capability != 0; i++ {
field := uint32(1 << i)
if capability&field == 0 {
continue
}
caps := make([]string, 0, bits.OnesCount32(capability))
for capability != 0 {
field := uint32(1 << bits.TrailingZeros32(capability))
capability ^= field

switch field {
Expand Down Expand Up @@ -642,13 +640,10 @@ func (c *Conn) CapabilityString() string {
// StatusString returns a "|" separated list of status fields. Example status values are SERVER_QUERY_WAS_SLOW and SERVER_STATUS_AUTOCOMMIT.
// These are defined as constants in the mysql package.
func (c *Conn) StatusString() string {
var stats []string
status := c.status
for i := 0; status != 0; i++ {
field := uint16(1 << i)
if status&field == 0 {
continue
}
stats := make([]string, 0, bits.OnesCount16(status))
for status != 0 {
field := uint16(1 << bits.TrailingZeros16(status))
status ^= field

switch field {
Expand Down
15 changes: 9 additions & 6 deletions replication/row_event.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import (
"encoding/hex"
"fmt"
"io"
"math/bits"
"strconv"
"strings"
"time"
Expand Down Expand Up @@ -754,7 +755,7 @@ func (e *TableMapEvent) VisibilityMap() map[int]bool {
if len(e.VisibilityBitmap) == 0 {
return nil
}
ret := make(map[int]bool)
ret := make(map[int]bool, len(e.VisibilityBitmap)*8)
i := 0
for _, field := range e.VisibilityBitmap {
for c := 0x80; c != 0; c >>= 1 {
Expand Down Expand Up @@ -1146,15 +1147,17 @@ func (e *RowsEvent) decodeImage(data []byte, bitmap []byte, rowImageType EnumRow
}

row := make([]interface{}, e.ColumnCount)
skips := make([]int, 0)

// refer: https://github.com/alibaba/canal/blob/c3e38e50e269adafdd38a48c63a1740cde304c67/dbsync/src/main/java/com/taobao/tddl/dbsync/binlog/event/RowsLogBuffer.java#L63
count := 0
for i := 0; i < int(e.ColumnCount); i++ {
if isBitSet(bitmap, i) {
count++
}
col := 0
for ; col+8 <= int(e.ColumnCount); col += 8 {
count += bits.OnesCount8(bitmap[col>>3])
}
if col < int(e.ColumnCount) {
count += bits.OnesCount8(bitmap[col>>3] & byte((1<<(int(e.ColumnCount)-col))-1))
}
skips := make([]int, 0, int(e.ColumnCount)-count)
count = bitmapByteSize(count)

nullBitmap := data[pos : pos+count]
Expand Down
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