64 lines of code to implement 0 copy of Go TCP unpacking sticky pack

This is a creation in Article, where the information may have evolved or changed. # 64 lines of code to implement 0 copy go tcp unpacking Sticky bag # # # Preface this time want to write a simple IM system with go, think about the go language TCP unpacking sticky packet. There are generally three solutions for the removal of packets from TCP. # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # The length of the message content can be transmitted using binary, high efficiency, recommended. Let's see how it's implemented. # # # Try to use the bytes that comes with the system library. Buffer Implementation code implementation: "' Gopackage tcpimport (" FMT "" Net "" Log "" bytes "" Encoding/binary ") const (bytes_size uint16 = 1024head_ SIZE int = 2) func startserver (address string) {listener, err: = Net. Listen ("TCP", address) if err! = Nil {log. Println ("Error listening", err.) Error ()) return}for {conn, err: = Listener. Accept () fmt. PRINTLN (Conn. REMOTEADDR ()) if err! = Nil {fmt. Println ("Error accepting", err.) Error ()) return//Termination program}go DOCONN (conn)}}func Doconn (conn net. Conn) {var (buffer = bytes. Newbuffer (Make ([]byte, 0, bytes_size)) BYTES = make ([]byte, bytes_size); ishead bool = truecontentsize Inthead = make ([]byt E, head_size) content = Make ([]byte, Bytes_size)) for {Readlen, err: = conn. Read (bytes); if err! = Nil {log. Println ("Error reading", err.) Error ())Return}_, err = buffer. Write (Bytes[0:readlen]) if err! = Nil {log. Println ("Error Writing to Buffer", err. Error ()) Return}for {if Ishead {if buffer. Len () >= Head_size {_, Err: = buffer. Read (head) if err! = Nil {fmt. Println ("Error reading", err.) Error ()) return}contentsize = int (binary). Bigendian.uint16 (head)) Ishead = false} else {break}}if!ishead {if buffer. Len () >= Contentsize {_, Err: = buffer. Read (Content[:contentsize]) if err! = Nil {fmt. Println ("Error reading", err.) Error ()) return}fmt. Println (String (content[:contentsize))) Ishead = true} else {break}}}} "' Test case: ' ' Gopackage tcpimport (" Testing "" NET "" FMT "" Encoding/binary ") func teststartserver (t *testing. T) {startserver ("localhost:50002")}func testclient (t *testing. T) {conn, err: = Net. Dial ("TCP", "localhost:50002") if err! = Nil {fmt. Println ("Error dialing", err.) Error ()) return//Termination program}var headsize Intvar headbytes = make ([]byte, 2) s: = "Hello world" content: = []byte (s) headsize = Len (content) binary. Bigendian.putuint16 (Headbytes, UInt16 (headsize)) Conn. Write (headbytes) Conn. Write (content) s = "Hello go" content = []byte (s) headsize = len (content) binary. Bigendian.putuint16 (Headbytes, UInt16 (headsize)) Conn. Write (headbytes) Conn. Write (content) s = "Hello tcp" content = []byte (s) headsize = len (content) binary. Bigendian.putuint16 (Headbytes, UInt16 (headsize)) Conn. Write (headbytes) Conn. Write (content)} ' execution result ' ' 127.0.0.1:51062hello worldhello gohello tcp ' with Go system library buffer, is not feel code particularly awkward, Two major drawbacks 1. Write a large amount of logic code to compensate for the non-applicability of the buffer to this scenario. 2. Performance is not high, there are three times memory copy, Coon->[]byte->buffer->[]byte. # # # own realization since the wheel is not suitable, you build the wheel, the first to achieve a own buffer, very simple, only more than 60 lines of code, all processes only one copy of the byte array, Conn->buffer, the rest of the operation is in the original buffer byte array operation "' Gopackage tcpimport (" Errors "" IO ") type buffer struct {reader IO. Readerbuf []bytestart intend Int}func newbuffer (reader io. Reader, Len int) buffer {buf: = make ([]byte, Len) return Buffer{reader, buf, 0, 0}}func (b *buffer) len () int {return b.end -b.start}//to move useful bytes forward Func (b *buffer) grow () {if B.start = = 0 {return}copy (b.buf, B.buf[b.start:b.end]) b.end-= B.staRtb.start = 0;} Read data from reader, if reader is blocked, there will be blocking func (b *buffer) Readfromreader () (int, error) {B.grow () n, err: = B.reader.read (b.buf[ B.end:]) if (err! = nil) {return n, err}b.end + = Nreturn N, nil}//returns n bytes without generating a shift func (b *buffer) Seek (n int) ([]byte, error) {if B.end-b.start >= n {buf: = B.buf[b.start:b.start+n]return buf, Nil}return Nil, errors. New ("Not Enough")}//discards the offset field, reads N fields func (b *buffer) read (offset, n int) ([]byte) {B.start + = Offsetbuf: = B.buf[b.start : B.start+n]b.start + = Nreturn buf} "and look at how to use it, and change the Doconn function above. "' Gofunc doconn (conn net. Conn) {var (buffer = Newbuffer (Conn, +) headbuf []bytecontentsize intcontentbuf []byte] for {_, Err: = Buffer.readfromreade R () If Err! = Nil {fmt. PRINTLN (Err) return}for {headbuf, err = Buffer.seek (head_size); if err! = Nil {break}contentsize = int (binary). Bigendian.uint16 (HEADBUF)) if (buffer. Len () >= contentsize-head_size) {contentbuf = Buffer.read (head_size, contentsize) fmt. Println (String (CONTENTBUF)) Continue}break}} ' ' Run down the test case and look at the result '' 127.0.0.1:51062hello worldhello Gohello TCP ' Source address: Https://github.com/alberliu/goim You have a better way to email me, alber_ Liu@qq.com, let me learn. 1875 views  ∙  2 likes