Permalink
Switch branches/tags
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
233 lines (205 sloc) 5.92 KB
// Copyright (c) 2012-2018 Ugorji Nwoke. All rights reserved.
// Use of this source code is governed by a MIT license found in the LICENSE file.
package codec
import (
"bufio"
"errors"
"io"
"net/rpc"
"sync"
)
// Rpc provides a rpc Server or Client Codec for rpc communication.
type Rpc interface {
ServerCodec(conn io.ReadWriteCloser, h Handle) rpc.ServerCodec
ClientCodec(conn io.ReadWriteCloser, h Handle) rpc.ClientCodec
}
// RPCOptions holds options specific to rpc functionality
type RPCOptions struct {
// RPCNoBuffer configures whether we attempt to buffer reads and writes during RPC calls.
//
// Set RPCNoBuffer=true to turn buffering off.
// Buffering can still be done if buffered connections are passed in, or
// buffering is configured on the handle.
RPCNoBuffer bool
}
// rpcCodec defines the struct members and common methods.
type rpcCodec struct {
c io.Closer
r io.Reader
w io.Writer
f ioFlusher
dec *Decoder
enc *Encoder
// bw *bufio.Writer
// br *bufio.Reader
mu sync.Mutex
h Handle
cls bool
clsmu sync.RWMutex
clsErr error
}
func newRPCCodec(conn io.ReadWriteCloser, h Handle) rpcCodec {
// return newRPCCodec2(bufio.NewReader(conn), bufio.NewWriter(conn), conn, h)
return newRPCCodec2(conn, conn, conn, h)
}
func newRPCCodec2(r io.Reader, w io.Writer, c io.Closer, h Handle) rpcCodec {
// defensive: ensure that jsonH has TermWhitespace turned on.
if jsonH, ok := h.(*JsonHandle); ok && !jsonH.TermWhitespace {
panic(errors.New("rpc requires a JsonHandle with TermWhitespace set to true"))
}
// always ensure that we use a flusher, and always flush what was written to the connection.
// we lose nothing by using a buffered writer internally.
f, ok := w.(ioFlusher)
bh := h.getBasicHandle()
if !bh.RPCNoBuffer {
if bh.WriterBufferSize <= 0 {
if !ok {
bw := bufio.NewWriter(w)
f, w = bw, bw
}
}
if bh.ReaderBufferSize <= 0 {
if _, ok = w.(ioPeeker); !ok {
if _, ok = w.(ioBuffered); !ok {
br := bufio.NewReader(r)
r = br
}
}
}
}
return rpcCodec{
c: c,
w: w,
r: r,
f: f,
h: h,
enc: NewEncoder(w, h),
dec: NewDecoder(r, h),
}
}
func (c *rpcCodec) write(obj1, obj2 interface{}, writeObj2 bool) (err error) {
if c.isClosed() {
return c.clsErr
}
err = c.enc.Encode(obj1)
if err == nil {
if writeObj2 {
err = c.enc.Encode(obj2)
}
// if err == nil && c.f != nil {
// err = c.f.Flush()
// }
}
if c.f != nil {
if err == nil {
err = c.f.Flush()
} else {
_ = c.f.Flush() // swallow flush error, so we maintain prior error on write
}
}
return
}
func (c *rpcCodec) swallow(err *error) {
defer panicToErr(c.dec, err)
c.dec.swallow()
}
func (c *rpcCodec) read(obj interface{}) (err error) {
if c.isClosed() {
return c.clsErr
}
//If nil is passed in, we should read and discard
if obj == nil {
// var obj2 interface{}
// return c.dec.Decode(&obj2)
c.swallow(&err)
return
}
return c.dec.Decode(obj)
}
func (c *rpcCodec) isClosed() (b bool) {
if c.c != nil {
c.clsmu.RLock()
b = c.cls
c.clsmu.RUnlock()
}
return
}
func (c *rpcCodec) Close() error {
if c.c == nil || c.isClosed() {
return c.clsErr
}
c.clsmu.Lock()
c.cls = true
c.clsErr = c.c.Close()
c.clsmu.Unlock()
return c.clsErr
}
func (c *rpcCodec) ReadResponseBody(body interface{}) error {
return c.read(body)
}
// -------------------------------------
type goRpcCodec struct {
rpcCodec
}
func (c *goRpcCodec) WriteRequest(r *rpc.Request, body interface{}) error {
// Must protect for concurrent access as per API
c.mu.Lock()
defer c.mu.Unlock()
return c.write(r, body, true)
}
func (c *goRpcCodec) WriteResponse(r *rpc.Response, body interface{}) error {
c.mu.Lock()
defer c.mu.Unlock()
return c.write(r, body, true)
}
func (c *goRpcCodec) ReadResponseHeader(r *rpc.Response) error {
return c.read(r)
}
func (c *goRpcCodec) ReadRequestHeader(r *rpc.Request) error {
return c.read(r)
}
func (c *goRpcCodec) ReadRequestBody(body interface{}) error {
return c.read(body)
}
// -------------------------------------
// goRpc is the implementation of Rpc that uses the communication protocol
// as defined in net/rpc package.
type goRpc struct{}
// GoRpc implements Rpc using the communication protocol defined in net/rpc package.
//
// Note: network connection (from net.Dial, of type io.ReadWriteCloser) is not buffered.
//
// For performance, you should configure WriterBufferSize and ReaderBufferSize on the handle.
// This ensures we use an adequate buffer during reading and writing.
// If not configured, we will internally initialize and use a buffer during reads and writes.
// This can be turned off via the RPCNoBuffer option on the Handle.
// var handle codec.JsonHandle
// handle.RPCNoBuffer = true // turns off attempt by rpc module to initialize a buffer
//
// Example 1: one way of configuring buffering explicitly:
// var handle codec.JsonHandle // codec handle
// handle.ReaderBufferSize = 1024
// handle.WriterBufferSize = 1024
// var conn io.ReadWriteCloser // connection got from a socket
// var serverCodec = GoRpc.ServerCodec(conn, handle)
// var clientCodec = GoRpc.ClientCodec(conn, handle)
//
// Example 2: you can also explicitly create a buffered connection yourself,
// and not worry about configuring the buffer sizes in the Handle.
// var handle codec.Handle // codec handle
// var conn io.ReadWriteCloser // connection got from a socket
// var bufconn = struct { // bufconn here is a buffered io.ReadWriteCloser
// io.Closer
// *bufio.Reader
// *bufio.Writer
// }{conn, bufio.NewReader(conn), bufio.NewWriter(conn)}
// var serverCodec = GoRpc.ServerCodec(bufconn, handle)
// var clientCodec = GoRpc.ClientCodec(bufconn, handle)
//
var GoRpc goRpc
func (x goRpc) ServerCodec(conn io.ReadWriteCloser, h Handle) rpc.ServerCodec {
return &goRpcCodec{newRPCCodec(conn, h)}
}
func (x goRpc) ClientCodec(conn io.ReadWriteCloser, h Handle) rpc.ClientCodec {
return &goRpcCodec{newRPCCodec(conn, h)}
}