//Package rpc provides abstract rpc server
//
//Copyright (C) 2022 Alexander Kiryukhin <i@neonxp.dev>
//
//This file is part of go.neonxp.dev/jsonrpc2 project.
//
//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 <https://www.gnu.org/licenses/>.
package rpc
import (
"context"
"encoding/json"
"io"
"sync"
"golang.org/x/sync/errgroup"
"go.neonxp.dev/jsonrpc2/transport"
)
const version = "2.0"
type RpcServer struct {
logger Logger
handlers map[string]Handler
middlewares []Middleware
transports []transport.Transport
mu sync.RWMutex
}
func New(opts ...Option) *RpcServer {
s := &RpcServer{
logger: nopLogger{},
handlers: map[string]Handler{},
transports: []transport.Transport{},
mu: sync.RWMutex{},
}
for _, opt := range opts {
opt(s)
}
return s
}
func (r *RpcServer) Use(opts ...Option) {
for _, opt := range opts {
opt(r)
}
}
func (r *RpcServer) Register(method string, handler Handler) {
r.mu.Lock()
defer r.mu.Unlock()
r.handlers[method] = handler
}
func (r *RpcServer) Run(ctx context.Context) error {
eg, ctx := errgroup.WithContext(ctx)
for _, t := range r.transports {
eg.Go(func(t transport.Transport) func() error {
return func() error { return t.Run(ctx, r) }
}(t))
}
return eg.Wait()
}
func (r *RpcServer) Resolve(ctx context.Context, rd io.Reader, w io.Writer, parallel bool) {
dec := json.NewDecoder(rd)
enc := json.NewEncoder(w)
mu := sync.Mutex{}
wg := sync.WaitGroup{}
for {
req := new(RpcRequest)
if err := dec.Decode(req); err != nil {
break
}
exec := func() {
h := r.callMethod
for _, m := range r.middlewares {
h = m(h)
}
resp := h(ctx, req)
if req.Id == nil {
// notification request
return
}
mu.Lock()
defer mu.Unlock()
if err := enc.Encode(resp); err != nil {
r.logger.Logf("Can't write response: %v", err)
WriteError(ErrCodeInternalError, enc)
}
if w, canFlush := w.(Flusher); canFlush {
w.Flush()
}
}
if parallel {
wg.Add(1)
go func(req *RpcRequest) {
defer wg.Done()
exec()
}(req)
} else {
exec()
}
}
if parallel {
wg.Wait()
}
}
func (r *RpcServer) callMethod(ctx context.Context, req *RpcRequest) *RpcResponse {
r.mu.RLock()
h, ok := r.handlers[req.Method]
r.mu.RUnlock()
if !ok {
return &RpcResponse{
Jsonrpc: version,
Error: ErrorFromCode(ErrCodeMethodNotFound),
Id: req.Id,
}
}
resp, err := h(ctx, req.Params)
if err != nil {
r.logger.Logf("User error %v", err)
return &RpcResponse{
Jsonrpc: version,
Error: err,
Id: req.Id,
}
}
return &RpcResponse{
Jsonrpc: version,
Result: resp,
Id: req.Id,
}
}
func WriteError(code int, enc *json.Encoder) {
enc.Encode(RpcResponse{
Jsonrpc: version,
Error: ErrorFromCode(code),
})
}
type RpcRequest struct {
Jsonrpc string `json:"jsonrpc"`
Method string `json:"method"`
Params json.RawMessage `json:"params"`
Id any `json:"id"`
}
type RpcResponse struct {
Jsonrpc string `json:"jsonrpc"`
Result json.RawMessage `json:"result,omitempty"`
Error error `json:"error,omitempty"`
Id any `json:"id,omitempty"`
}
type Flusher interface {
// Flush sends any buffered data to the client.
Flush()
}
