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[go/mysql] combine ephemeral buffers into one field #4256

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Merged
sougou merged 1 commit into from
Oct 9, 2018
Merged

[go/mysql] combine ephemeral buffers into one field #4256

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41 changes: 19 additions & 22 deletions go/mysql/conn.go
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Original file line number Diff line number Diff line change
Expand Up @@ -41,10 +41,10 @@ const (
// read or write a packet while one is already used.
ephemeralUnused = iota

// ephemeralWrite means we currently in process of writing currentEphemeralWriteBuffer
// ephemeralWrite means we currently in process of writing from currentEphemeralBuffer
ephemeralWrite

// ephemeralRead means we currently in process of reading into currentEphemeralReadBuffer
// ephemeralRead means we currently in process of reading into currentEphemeralBuffer
ephemeralRead
)

Expand Down Expand Up @@ -141,12 +141,9 @@ type Conn struct {
// - startEphemeralPacket / writeEphemeralPacket methods for writes.
// - readEphemeralPacket / recycleReadPacket methods for reads.
currentEphemeralPolicy int
// TODO (danieltahara): Ultimately get rid of this delineation.
// currentEphemeralWriteBuffer and currentEphemeralReadBuffer used for tracking
// allocated temporary buffers for writes and reads respectively. They can be allocated
// from bufPool or heap and should be recycled in the same manner.
currentEphemeralWriteBuffer *[]byte
currentEphemeralReadBuffer *[]byte
// currentEphemeralBuffer for tracking allocated temporary buffer for writes and reads respectively.
// It can be allocated from bufPool or heap and should be recycled in the same manner.
currentEphemeralBuffer *[]byte
}

// bufPool is used to allocate and free buffers in an efficient way.
Expand Down Expand Up @@ -278,11 +275,11 @@ func (c *Conn) readEphemeralPacket() ([]byte, error) {
c.currentEphemeralPolicy = ephemeralRead
// Use the bufPool.
if length < MaxPacketSize {
c.currentEphemeralReadBuffer = bufPool.Get(length)
if _, err := io.ReadFull(r, *c.currentEphemeralReadBuffer); err != nil {
c.currentEphemeralBuffer = bufPool.Get(length)
if _, err := io.ReadFull(r, *c.currentEphemeralBuffer); err != nil {
return nil, fmt.Errorf("io.ReadFull(packet body of length %v) failed: %v", length, err)
}
return *c.currentEphemeralReadBuffer, nil
return *c.currentEphemeralBuffer, nil
}

// Much slower path, revert to allocating everything from scratch.
Expand Down Expand Up @@ -337,11 +334,11 @@ func (c *Conn) readEphemeralPacketDirect() ([]byte, error) {

c.currentEphemeralPolicy = ephemeralRead
if length < MaxPacketSize {
c.currentEphemeralReadBuffer = bufPool.Get(length)
if _, err := io.ReadFull(r, *c.currentEphemeralReadBuffer); err != nil {
c.currentEphemeralBuffer = bufPool.Get(length)
if _, err := io.ReadFull(r, *c.currentEphemeralBuffer); err != nil {
return nil, fmt.Errorf("io.ReadFull(packet body of length %v) failed: %v", length, err)
}
return *c.currentEphemeralReadBuffer, nil
return *c.currentEphemeralBuffer, nil
}

return nil, fmt.Errorf("readEphemeralPacketDirect doesn't support more than one packet")
Expand All @@ -352,10 +349,10 @@ func (c *Conn) readEphemeralPacketDirect() ([]byte, error) {
func (c *Conn) recycleReadPacket() {
switch c.currentEphemeralPolicy {
case ephemeralRead:
if c.currentEphemeralReadBuffer != nil {
if c.currentEphemeralBuffer != nil {
// We are using the pool, put the buffer back in.
bufPool.Put(c.currentEphemeralReadBuffer)
c.currentEphemeralReadBuffer = nil
bufPool.Put(c.currentEphemeralBuffer)
c.currentEphemeralBuffer = nil
}
case ephemeralUnused, ephemeralWrite:
// Programming error.
Expand Down Expand Up @@ -502,8 +499,8 @@ func (c *Conn) startEphemeralPacket(length int) []byte {

c.currentEphemeralPolicy = ephemeralWrite
// get buffer from pool or it'll be allocated if length is too big
c.currentEphemeralWriteBuffer = bufPool.Get(length)
return *c.currentEphemeralWriteBuffer
c.currentEphemeralBuffer = bufPool.Get(length)
return *c.currentEphemeralBuffer
}

// writeEphemeralPacket writes the packet that was allocated by
Expand All @@ -513,7 +510,7 @@ func (c *Conn) writeEphemeralPacket() error {

switch c.currentEphemeralPolicy {
case ephemeralWrite:
if err := c.writePacket(*c.currentEphemeralWriteBuffer); err != nil {
if err := c.writePacket(*c.currentEphemeralBuffer); err != nil {
return fmt.Errorf("Conn %v: %v", c.ID(), err)
}
case ephemeralUnused, ephemeralRead:
Expand All @@ -530,8 +527,8 @@ func (c *Conn) recycleWritePacket() {
switch c.currentEphemeralPolicy {
case ephemeralWrite:
// Release our reference so the buffer can be gced
bufPool.Put(c.currentEphemeralWriteBuffer)
c.currentEphemeralWriteBuffer = nil
bufPool.Put(c.currentEphemeralBuffer)
c.currentEphemeralBuffer = nil
case ephemeralUnused, ephemeralRead:
// Programming error.
panic(fmt.Errorf("trying to call recycleWritePacket while currentEphemeralPolicy is %d", c.currentEphemeralPolicy))
Expand Down