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srpc.go
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srpc.go
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// Copyright 2016 Platina Systems, Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package srpc gives symmetric bi-directional RPC on top of GO rpc.
// Two hosts connected via are Client and server both expose RPC calls to each other.
// Either host may make RPC calls to the other: so each host is both client and server at the same time.
package srpc
import (
"encoding/binary"
"fmt"
"io"
"net/rpc"
"sync"
"github.com/platinasystems/elib"
"github.com/platinasystems/elib/elog"
)
type input struct {
buf []byte
recycle bool
}
type side struct {
wbuf elib.ByteVec
overflow elib.ByteVec
rx chan input
}
type conn struct {
wlock sync.Mutex
wc io.WriteCloser
recycle chan elib.ByteVec
sides [2]side
eventTagIndex int
}
// Get buffer from recycler or return nil if none is available.
func (c *conn) getBuf() (b elib.ByteVec) {
select {
case b = <-c.recycle:
b = b[:0]
default:
b = make([]byte, 0, 4096)
}
return
}
// Recycle buffer.
func (c *conn) putBuf(b elib.ByteVec) {
select {
case c.recycle <- b:
default:
}
}
type Server struct {
r io.Reader
conn conn
c ClientConn
s ServerConn
*rpc.Client
*rpc.Server
EventTag string
}
func (c *conn) Read(p []byte, isClient int) (n int, err error) {
e, o := c.logf(eventFlag(0), isClient, "enter")
defer func() { c.logExit(e, p, n, o, err) }()
s := &c.sides[isClient]
// Copy from overflow.
if len(s.overflow) > 0 {
n = copy(p, s.overflow)
if len(s.overflow) == n {
s.overflow = s.overflow[:0]
} else {
s.overflow = s.overflow[n:]
}
return
}
// Wait for next frame sent from input routine.
i := <-s.rx
n = copy(p, i.buf)
if n < len(i.buf) {
s.overflow = append(s.overflow, i.buf[n:]...)
}
if i.recycle {
c.putBuf(i.buf)
}
return
}
func (c *conn) Write(p []byte, isClient int) (n int, err error) {
c.wlock.Lock()
defer c.wlock.Unlock()
e, o := c.logf(IsWrite, isClient, "enter")
defer func() { c.logExit(e, p, n, o, err) }()
side := &c.sides[isClient]
n = len(p)
wb := framePut(side.wbuf, n, isClient)
wb = append(wb, p...)
l := 0
for l < len(wb) {
var i int
i, err = c.wc.Write(wb[l:])
if err != nil {
return
}
l += i
}
// Reuse it for next call.
side.wbuf = wb[:0]
return
}
func (c *conn) Close(isClient int) error {
close(c.sides[isClient^1].rx)
return c.wc.Close()
}
type ClientConn struct{ *conn }
type ServerConn struct{ *conn }
func (c *ClientConn) Read(p []byte) (n int, err error) { return c.conn.Read(p, 1) }
func (c *ServerConn) Read(p []byte) (n int, err error) { return c.conn.Read(p, 0) }
func (c *ClientConn) Write(b []byte) (n int, err error) { return c.conn.Write(b, 1) }
func (c *ServerConn) Write(b []byte) (n int, err error) { return c.conn.Write(b, 0) }
func (c *ClientConn) Close() error { return c.conn.Close(1) }
func (c *ServerConn) Close() error { return c.conn.Close(0) }
// Framing encodes length plus whether frame is from client or server side.
func framePut(b []byte, l int, isClient int) []byte {
vi := uint64(0)
if isClient != 0 {
vi = 1
}
vi += 2 * uint64(l)
var tmp [binary.MaxVarintLen64]byte
n := binary.PutUvarint(tmp[:], vi)
for i := 0; i < n; i++ {
b = append(b, tmp[i])
}
return b
}
func frameGet(b []byte) (isClient int, l int, n int) {
vi, n := binary.Uvarint(b)
isClient = int(vi & 1)
l = int(vi >> 1)
return
}
func (r *Server) Input(b []byte) (n int) {
var lastContentLen, lastFrameIsClient int
nLeft := len(b)
c := &r.conn
e := inputEvent{}
t := elog.PutUvarint(e.s[:], c.eventTagIndex)
elog.PutData(t, b)
e.Log()
for {
frameIsClient, contentLen, headerLen := frameGet(b[n:])
frameLen := contentLen + headerLen
frameValid := headerLen > 0 && nLeft >= frameLen
if lastContentLen > 0 {
// Client frames go to server;
// server frames are read by client.
s := &r.conn.sides[lastFrameIsClient^1]
i := input{buf: b[n-lastContentLen : n]}
// Only recycle buffer for last frame in buffer.
i.recycle = !frameValid
s.rx <- i
}
if !frameValid {
break
}
lastContentLen = contentLen
lastFrameIsClient = frameIsClient
n += frameLen
nLeft -= frameLen
}
return
}
func (r *Server) Serve() error {
var b []byte
for {
var c [4096]byte
n, err := r.r.Read(c[:])
if err != nil {
return err
}
b = append(b, c[:n]...)
l := r.Input(b)
nextBuf := r.conn.getBuf()
if l < len(b) {
nextBuf = append(nextBuf, b[l:]...)
}
b = nextBuf
}
}
func (r *Server) init(wc io.WriteCloser, regs []interface{}) {
c := &r.conn
c.wc = wc
for i := range c.sides {
c.sides[i].rx = make(chan input, 64)
}
r.c.conn = c
r.s.conn = c
r.Client = rpc.NewClient(&r.c)
r.Server = rpc.NewServer()
for i := range regs {
r.Register(regs[i])
}
if len(r.EventTag) > 0 {
c.eventTagIndex = eventType.TagIndex(r.EventTag)
}
go r.Server.ServeConn(&r.s)
}
func (r *Server) Init(rwc io.ReadWriteCloser, regs ...interface{}) {
r.r = rwc
r.conn.recycle = make(chan elib.ByteVec, 64)
r.init(rwc, regs)
}
func (r *Server) InitWriter(wc io.WriteCloser, recycle chan elib.ByteVec, regs ...interface{}) {
r.r = nil
r.conn.recycle = recycle
r.init(wc, regs)
}
// Event logging.
type event struct {
flags eventFlag
s [elog.EventDataBytes - 1]byte
}
//go:generate gentemplate -d Package=srpc -id event -d Type=event github.com/platinasystems/elib/elog/event.tmpl
type eventFlag uint8
const (
IsWrite eventFlag = 1 << iota
IsClient
IsData
)
func (c *conn) logf(f eventFlag, isClient int, format string, args ...interface{}) (e event, ti int) {
e = event{flags: f}
if isClient != 0 {
e.flags |= IsClient
}
ti = binary.PutUvarint(e.s[:], uint64(c.eventTagIndex))
elog.Printf(e.s[ti:], format, args...)
e.Log()
return
}
func (c *conn) logExit(e event, p []byte, n, o int, err error) {
if err != nil {
elog.Printf(e.s[o:], "error %s", err)
} else {
e.setData(p, n, o)
}
e.Log()
}
func (e *event) setData(p []byte, n, o int) {
e.flags |= IsData
i := binary.PutUvarint(e.s[o:], uint64(n))
copy(e.s[o+i:], p[:n])
}
func (e *event) String() string {
side := "server"
rw := "read"
if e.flags&IsClient != 0 {
side = "client"
}
if e.flags&IsWrite != 0 {
rw = "write"
}
b, tagIndex := elog.Uvarint(e.s[:])
tag := eventType.Tag(int(tagIndex), " ")
if e.flags&IsData != 0 {
return fmt.Sprintf("rpc %s%s %s %s", tag, side, rw, elog.HexData(b))
} else {
return fmt.Sprintf("rpc %s%s %s %s", tag, side, rw, elog.String(b))
}
}
func (e *event) Encode(b []byte) int {
b[0] = byte(e.flags)
copy(b[1:], e.s[:])
return 1 + len(e.s)
}
func (e *event) Decode(b []byte) int {
e.flags = eventFlag(b[0])
copy(e.s[:], b[1:])
return 1 + len(e.s)
}
type inputEventFlag uint8
const (
isFrame inputEventFlag = 1 << iota
)
type inputEvent struct {
flags inputEventFlag
s [elog.EventDataBytes - 1]byte
}
//go:generate gentemplate -d Package=srpc -id inputEvent -d Type=inputEvent github.com/platinasystems/elib/elog/event.tmpl
func (e *inputEvent) String() string {
b, tagIndex := elog.Uvarint(e.s[:])
tag := eventType.Tag(int(tagIndex), " ")
s := ""
if e.flags&isFrame != 0 {
s = "frame "
}
return fmt.Sprintf("rpc %sinput %s%s", tag, s, elog.HexData(b))
}
func (e *inputEvent) Encode(b []byte) int {
b[0] = byte(e.flags)
copy(b[1:], e.s[:])
return 1 + len(e.s)
}
func (e *inputEvent) Decode(b []byte) int {
e.flags = inputEventFlag(b[0])
copy(e.s[:], b[1:])
return 1 + len(e.s)
}