golang有效的二进制编码

Question

I have a program that sends udp packets. a packet datagram is represented by the following struct (notice that the size of the packet isn't fixed):

type packet struct {
    dataLength uint16
    id [8]byte
    pairity, shards, flags byte
    blob []byte // length defined by dataLength 
}

I used encoding/binary package to do serialization/deserialization but it wasn't efficient enough (used pprof). it wasted alot of CPU time and I couldn't utilize the whole network speed because of that.

for example, consider the following code:

packet := packet{
    dataLength: 4,
    id: [8]byte{1,2,3,4,5,6,7,8},
    pairity: 10,
    shards: 50,
    flags: 200,
    blob: []byte{1,2,3,4},
}
bufToSendOverNetwork := packet.ToBytes()

What is the most efficient way to do this operation (and also the .FromBytes operation)

Answer 1

encoding/binary.Write uses reflection, so it will be slower than anything that manually constructs the buffer. Below is an example of such a function:

import (
    "encoding/binary"
)

func (p *packet) ToBytes() []byte {
    buff := make([]byte, 2 + 8 + 3 + len(p.blob))

    binary.BigEndian.PutUint16(buff[:2], p.dataLength)
    copy(buff[2:10], p.id[:])
    buff[10] = p.pairity
    buff[11] = p.shards
    buff[12] = p.flags
    copy(buff[13:], p.blob)

    return buff
}