/
server.go
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/
server.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package frame
import (
"fmt"
"io"
"go.uber.org/atomic"
"go.uber.org/multierr"
)
// Handler handles incoming framed requests.
type Handler interface {
// Receives the given framed request and responds to it.
Handle([]byte) ([]byte, error)
}
// Server provides bidirectional incoming framed communication.
//
// It allows receiving framed requests and responding to them.
type Server struct {
r *Reader
w *Writer
running *atomic.Bool
}
// NewServer builds a new server which reads requests from the given Reader
// and writes responses to the given Writer.
func NewServer(r io.Reader, w io.Writer) *Server {
return &Server{
r: NewReader(r),
w: NewWriter(w),
running: atomic.NewBool(false),
}
}
// Serve serves the given Handler with the Server.
//
// Only one request is served at a time. The server stops handling requests if
// there is an IO error or an unhandled error is received from the Handler.
//
// This blocks until the server is stopped using Stop.
func (s *Server) Serve(h Handler) (err error) {
if s.running.Swap(true) {
return fmt.Errorf("server is already running")
}
defer func() {
err = multierr.Append(err, s.r.Close())
err = multierr.Append(err, s.w.Close())
}()
for s.running.Load() {
req, err := s.r.Read()
if err != nil {
// If the error occurred because the server was stopped, ignore it.
if !s.running.Load() {
break
}
return err
}
res, err := h.Handle(req)
if err != nil {
return err
}
if err := s.w.Write(res); err != nil {
return err
}
}
return nil
}
// Stop tells the Server that it's okay to stop Serve.
//
// This is a no-op if the server wasn't already running.
func (s *Server) Stop() error {
// We only close the reader because we want the writer to be available if
// Stop() was called by a request handler which still needs to send back a
// response (goodbye()). The writer will be closed automatically when the
// loop exits.
if s.running.Swap(false) {
return s.r.Close()
}
return nil
}