--- /dev/null
+// Copyright 2020 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 jsonrpc2
+
+import (
+ "context"
+ "fmt"
+ "io"
+ "net"
+ "os"
+ "time"
+
+ "golang.org/x/tools/internal/event"
+ errors "golang.org/x/xerrors"
+)
+
+// NOTE: This file provides an experimental API for serving multiple remote
+// jsonrpc2 clients over the network. For now, it is intentionally similar to
+// net/http, but that may change in the future as we figure out the correct
+// semantics.
+
+// A StreamServer is used to serve incoming jsonrpc2 clients communicating over
+// a newly created connection.
+type StreamServer interface {
+ ServeStream(context.Context, Conn) error
+}
+
+// The ServerFunc type is an adapter that implements the StreamServer interface
+// using an ordinary function.
+type ServerFunc func(context.Context, Conn) error
+
+// ServeStream calls f(ctx, s).
+func (f ServerFunc) ServeStream(ctx context.Context, c Conn) error {
+ return f(ctx, c)
+}
+
+// HandlerServer returns a StreamServer that handles incoming streams using the
+// provided handler.
+func HandlerServer(h Handler) StreamServer {
+ return ServerFunc(func(ctx context.Context, conn Conn) error {
+ conn.Go(ctx, h)
+ <-conn.Done()
+ return conn.Err()
+ })
+}
+
+// ListenAndServe starts an jsonrpc2 server on the given address. If
+// idleTimeout is non-zero, ListenAndServe exits after there are no clients for
+// this duration, otherwise it exits only on error.
+func ListenAndServe(ctx context.Context, network, addr string, server StreamServer, idleTimeout time.Duration) error {
+ ln, err := net.Listen(network, addr)
+ if err != nil {
+ return err
+ }
+ defer ln.Close()
+ if network == "unix" {
+ defer os.Remove(addr)
+ }
+ return Serve(ctx, ln, server, idleTimeout)
+}
+
+// Serve accepts incoming connections from the network, and handles them using
+// the provided server. If idleTimeout is non-zero, ListenAndServe exits after
+// there are no clients for this duration, otherwise it exits only on error.
+func Serve(ctx context.Context, ln net.Listener, server StreamServer, idleTimeout time.Duration) error {
+ ctx, cancel := context.WithCancel(ctx)
+ defer cancel()
+ // Max duration: ~290 years; surely that's long enough.
+ const forever = 1<<63 - 1
+ if idleTimeout <= 0 {
+ idleTimeout = forever
+ }
+ connTimer := time.NewTimer(idleTimeout)
+
+ newConns := make(chan net.Conn)
+ doneListening := make(chan error)
+ closedConns := make(chan error)
+
+ go func() {
+ for {
+ nc, err := ln.Accept()
+ if err != nil {
+ select {
+ case doneListening <- fmt.Errorf("Accept(): %w", err):
+ case <-ctx.Done():
+ }
+ return
+ }
+ newConns <- nc
+ }
+ }()
+
+ activeConns := 0
+ for {
+ select {
+ case netConn := <-newConns:
+ activeConns++
+ connTimer.Stop()
+ stream := NewHeaderStream(netConn)
+ go func() {
+ conn := NewConn(stream)
+ closedConns <- server.ServeStream(ctx, conn)
+ stream.Close()
+ }()
+ case err := <-doneListening:
+ return err
+ case err := <-closedConns:
+ if !isClosingError(err) {
+ event.Error(ctx, "closed a connection", err)
+ }
+ activeConns--
+ if activeConns == 0 {
+ connTimer.Reset(idleTimeout)
+ }
+ case <-connTimer.C:
+ return ErrIdleTimeout
+ case <-ctx.Done():
+ return ctx.Err()
+ }
+ }
+}
+
+// isClosingError reports if the error occurs normally during the process of
+// closing a network connection. It uses imperfect heuristics that err on the
+// side of false negatives, and should not be used for anything critical.
+func isClosingError(err error) bool {
+ if errors.Is(err, io.EOF) {
+ return true
+ }
+ // Per https://github.com/golang/go/issues/4373, this error string should not
+ // change. This is not ideal, but since the worst that could happen here is
+ // some superfluous logging, it is acceptable.
+ if err.Error() == "use of closed network connection" {
+ return true
+ }
+ return false
+}