Files
cgrates/utils/concureqs_json_codec.go
2020-07-09 17:27:11 +03:00

134 lines
3.4 KiB
Go

/*
Real-time Online/Offline Charging System (OCS) for Telecom & ISP environments
Copyright (C) ITsysCOM GmbH
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>
*/
// Most of the logic follows standard library implementation in this file
package utils
import (
"encoding/json"
"errors"
"io"
"net/rpc"
"sync"
)
type concReqsServerCodec struct {
dec *json.Decoder // for reading JSON values
enc *json.Encoder // for writing JSON values
c io.Closer
// temporary work space
req serverRequest
// JSON-RPC clients can use arbitrary json values as request IDs.
// Package rpc expects uint64 request IDs.
// We assign uint64 sequence numbers to incoming requests
// but save the original request ID in the pending map.
// When rpc responds, we use the sequence number in
// the response to find the original request ID.
mutex sync.Mutex // protects seq, pending
seq uint64
pending map[uint64]*json.RawMessage
allocated bool // populated if we have allocated a channel for concurrent requests
}
// NewConcReqsServerCodec returns a new rpc.ServerCodec using JSON-RPC on conn.
func NewConcReqsServerCodec(conn io.ReadWriteCloser) rpc.ServerCodec {
return &concReqsServerCodec{
dec: json.NewDecoder(conn),
enc: json.NewEncoder(conn),
c: conn,
pending: make(map[uint64]*json.RawMessage),
}
}
func (c *concReqsServerCodec) ReadRequestHeader(r *rpc.Request) error {
c.req.reset()
if err := c.dec.Decode(&c.req); err != nil {
return err
}
r.ServiceMethod = c.req.Method
// JSON request id can be any JSON value;
// RPC package expects uint64. Translate to
// internal uint64 and save JSON on the side.
c.mutex.Lock()
c.seq++
c.pending[c.seq] = c.req.Id
c.req.Id = nil
r.Seq = c.seq
c.mutex.Unlock()
return nil
}
func (c *concReqsServerCodec) ReadRequestBody(x interface{}) error {
if err := ConReqs.Allocate(); err != nil {
return err
}
c.allocated = true
if x == nil {
return nil
}
if c.req.Params == nil {
return errMissingParams
}
// JSON params is array value.
// RPC params is struct.
// Unmarshal into array containing struct for now.
// Should think about making RPC more general.
var params [1]interface{}
params[0] = x
return json.Unmarshal(*c.req.Params, &params)
}
func (c *concReqsServerCodec) WriteResponse(r *rpc.Response, x interface{}) error {
if c.allocated {
defer func() {
ConReqs.Deallocate()
c.allocated = false
}()
}
c.mutex.Lock()
b, ok := c.pending[r.Seq]
if !ok {
c.mutex.Unlock()
return errors.New("invalid sequence number in response")
}
delete(c.pending, r.Seq)
c.mutex.Unlock()
if b == nil {
// Invalid request so no id. Use JSON null.
b = &null
}
resp := serverResponse{Id: b}
if r.Error == "" {
resp.Result = x
} else {
resp.Error = r.Error
}
return c.enc.Encode(resp)
}
func (c *concReqsServerCodec) Close() error {
return c.c.Close()
}