mirror of
https://github.com/go-gitea/gitea.git
synced 2024-08-30 16:17:28 +02:00
198 lines
4.6 KiB
Go
198 lines
4.6 KiB
Go
package gomemcached
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import (
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"encoding/binary"
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"fmt"
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"io"
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)
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// The maximum reasonable body length to expect.
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// Anything larger than this will result in an error.
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// The current limit, 20MB, is the size limit supported by ep-engine.
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var MaxBodyLen = int(20 * 1024 * 1024)
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// MCRequest is memcached Request
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type MCRequest struct {
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// The command being issued
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Opcode CommandCode
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// The CAS (if applicable, or 0)
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Cas uint64
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// An opaque value to be returned with this request
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Opaque uint32
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// The vbucket to which this command belongs
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VBucket uint16
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// Command extras, key, and body
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Extras, Key, Body, ExtMeta []byte
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// Datatype identifier
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DataType uint8
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}
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// Size gives the number of bytes this request requires.
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func (req *MCRequest) Size() int {
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return HDR_LEN + len(req.Extras) + len(req.Key) + len(req.Body) + len(req.ExtMeta)
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}
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// A debugging string representation of this request
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func (req MCRequest) String() string {
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return fmt.Sprintf("{MCRequest opcode=%s, bodylen=%d, key='%s'}",
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req.Opcode, len(req.Body), req.Key)
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}
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func (req *MCRequest) fillHeaderBytes(data []byte) int {
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pos := 0
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data[pos] = REQ_MAGIC
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pos++
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data[pos] = byte(req.Opcode)
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pos++
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binary.BigEndian.PutUint16(data[pos:pos+2],
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uint16(len(req.Key)))
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pos += 2
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// 4
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data[pos] = byte(len(req.Extras))
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pos++
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// Data type
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if req.DataType != 0 {
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data[pos] = byte(req.DataType)
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}
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pos++
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binary.BigEndian.PutUint16(data[pos:pos+2], req.VBucket)
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pos += 2
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// 8
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binary.BigEndian.PutUint32(data[pos:pos+4],
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uint32(len(req.Body)+len(req.Key)+len(req.Extras)+len(req.ExtMeta)))
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pos += 4
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// 12
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binary.BigEndian.PutUint32(data[pos:pos+4], req.Opaque)
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pos += 4
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// 16
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if req.Cas != 0 {
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binary.BigEndian.PutUint64(data[pos:pos+8], req.Cas)
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}
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pos += 8
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if len(req.Extras) > 0 {
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copy(data[pos:pos+len(req.Extras)], req.Extras)
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pos += len(req.Extras)
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}
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if len(req.Key) > 0 {
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copy(data[pos:pos+len(req.Key)], req.Key)
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pos += len(req.Key)
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}
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return pos
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}
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// HeaderBytes will return the wire representation of the request header
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// (with the extras and key).
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func (req *MCRequest) HeaderBytes() []byte {
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data := make([]byte, HDR_LEN+len(req.Extras)+len(req.Key))
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req.fillHeaderBytes(data)
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return data
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}
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// Bytes will return the wire representation of this request.
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func (req *MCRequest) Bytes() []byte {
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data := make([]byte, req.Size())
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pos := req.fillHeaderBytes(data)
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if len(req.Body) > 0 {
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copy(data[pos:pos+len(req.Body)], req.Body)
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}
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if len(req.ExtMeta) > 0 {
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copy(data[pos+len(req.Body):pos+len(req.Body)+len(req.ExtMeta)], req.ExtMeta)
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}
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return data
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}
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// Transmit will send this request message across a writer.
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func (req *MCRequest) Transmit(w io.Writer) (n int, err error) {
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if len(req.Body) < 128 {
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n, err = w.Write(req.Bytes())
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} else {
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n, err = w.Write(req.HeaderBytes())
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if err == nil {
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m := 0
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m, err = w.Write(req.Body)
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n += m
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}
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}
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return
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}
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// Receive will fill this MCRequest with the data from a reader.
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func (req *MCRequest) Receive(r io.Reader, hdrBytes []byte) (int, error) {
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if len(hdrBytes) < HDR_LEN {
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hdrBytes = []byte{
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0}
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}
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n, err := io.ReadFull(r, hdrBytes)
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if err != nil {
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return n, err
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}
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if hdrBytes[0] != RES_MAGIC && hdrBytes[0] != REQ_MAGIC {
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return n, fmt.Errorf("bad magic: 0x%02x", hdrBytes[0])
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}
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klen := int(binary.BigEndian.Uint16(hdrBytes[2:]))
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elen := int(hdrBytes[4])
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// Data type at 5
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req.DataType = uint8(hdrBytes[5])
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req.Opcode = CommandCode(hdrBytes[1])
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// Vbucket at 6:7
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req.VBucket = binary.BigEndian.Uint16(hdrBytes[6:])
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totalBodyLen := int(binary.BigEndian.Uint32(hdrBytes[8:]))
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req.Opaque = binary.BigEndian.Uint32(hdrBytes[12:])
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req.Cas = binary.BigEndian.Uint64(hdrBytes[16:])
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if totalBodyLen > 0 {
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buf := make([]byte, totalBodyLen)
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m, err := io.ReadFull(r, buf)
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n += m
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if err == nil {
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if req.Opcode >= TAP_MUTATION &&
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req.Opcode <= TAP_CHECKPOINT_END &&
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len(buf) > 1 {
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// In these commands there is "engine private"
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// data at the end of the extras. The first 2
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// bytes of extra data give its length.
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elen += int(binary.BigEndian.Uint16(buf))
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}
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req.Extras = buf[0:elen]
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req.Key = buf[elen : klen+elen]
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// get the length of extended metadata
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extMetaLen := 0
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if elen > 29 {
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extMetaLen = int(binary.BigEndian.Uint16(req.Extras[28:30]))
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}
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bodyLen := totalBodyLen - klen - elen - extMetaLen
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if bodyLen > MaxBodyLen {
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return n, fmt.Errorf("%d is too big (max %d)",
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bodyLen, MaxBodyLen)
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}
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req.Body = buf[klen+elen : klen+elen+bodyLen]
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req.ExtMeta = buf[klen+elen+bodyLen:]
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}
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}
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return n, err
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}
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