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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package jsonrpc implements a JSON-RPC ClientCodec and ServerCodec
// for the rpc package.
package jsonrpc
import (
"fmt"
"io"
"json"
"net"
"rpc"
"sync"
)
type clientCodec struct {
dec *json.Decoder // for reading JSON values
enc *json.Encoder // for writing JSON values
c io.Closer
// temporary work space
req clientRequest
resp clientResponse
// JSON-RPC responses include the request id but not the request method.
// Package rpc expects both.
// We save the request method in pending when sending a request
// and then look it up by request ID when filling out the rpc Response.
mutex sync.Mutex // protects pending
pending map[uint64]string // map request id to method name
}
// NewClientCodec returns a new rpc.ClientCodec using JSON-RPC on conn.
func NewClientCodec(conn io.ReadWriteCloser) rpc.ClientCodec {
return &clientCodec{
dec: json.NewDecoder(conn),
enc: json.NewEncoder(conn),
c: conn,
pending: make(map[uint64]string),
}
}
type clientRequest struct {
Method string `json:"method"`
Params [1]interface{} `json:"params"`
Id uint64 `json:"id"`
}
func (c *clientCodec) WriteRequest(r *rpc.Request, param interface{}) error {
c.mutex.Lock()
c.pending[r.Seq] = r.ServiceMethod
c.mutex.Unlock()
c.req.Method = r.ServiceMethod
c.req.Params[0] = param
c.req.Id = r.Seq
return c.enc.Encode(&c.req)
}
type clientResponse struct {
Id uint64 `json:"id"`
Result *json.RawMessage `json:"result"`
Error interface{} `json:"error"`
}
func (r *clientResponse) reset() {
r.Id = 0
r.Result = nil
r.Error = nil
}
func (c *clientCodec) ReadResponseHeader(r *rpc.Response) error {
c.resp.reset()
if err := c.dec.Decode(&c.resp); err != nil {
return err
}
c.mutex.Lock()
r.ServiceMethod = c.pending[c.resp.Id]
delete(c.pending, c.resp.Id)
c.mutex.Unlock()
r.Error = ""
r.Seq = c.resp.Id
if c.resp.Error != nil {
x, ok := c.resp.Error.(string)
if !ok {
return fmt.Errorf("invalid error %v", c.resp.Error)
}
if x == "" {
x = "unspecified error"
}
r.Error = x
}
return nil
}
func (c *clientCodec) ReadResponseBody(x interface{}) error {
if x == nil {
return nil
}
return json.Unmarshal(*c.resp.Result, x)
}
func (c *clientCodec) Close() error {
return c.c.Close()
}
// NewClient returns a new rpc.Client to handle requests to the
// set of services at the other end of the connection.
func NewClient(conn io.ReadWriteCloser) *rpc.Client {
return rpc.NewClientWithCodec(NewClientCodec(conn))
}
// Dial connects to a JSON-RPC server at the specified network address.
func Dial(network, address string) (*rpc.Client, error) {
conn, err := net.Dial(network, address)
if err != nil {
return nil, err
}
return NewClient(conn), err
}
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