90 lines
2.7 KiB
Go
90 lines
2.7 KiB
Go
// Copyright 2016-2017, Pulumi Corporation. All rights reserved.
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package rpcutil
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import (
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"net"
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"os"
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"os/signal"
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"strconv"
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"strings"
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"syscall"
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"github.com/pkg/errors"
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"google.golang.org/grpc"
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"google.golang.org/grpc/reflection"
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)
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// IsBenignCloseErr returns true if the error is "expected" upon shutdown of the server.
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func IsBenignCloseErr(err error) bool {
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msg := err.Error()
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return strings.HasSuffix(msg, "use of closed network connection") ||
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strings.HasSuffix(msg, "grpc: the server has been stopped")
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}
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// Serve creates a new gRPC server, calls out to the supplied registration functions to bind interfaces, and then
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// listens on the supplied TCP port. If the caller wishes for the kernel to choose a free port automatically, pass 0 as
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// the port number. The return values are: the chosen port (the same as supplied if non-0), a channel that may
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// eventually return an error, and an error, in case something went wrong. The channel is non-nil and waits until
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// the server is finished, in the case of a successful launch of the RPC server.
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func Serve(port int, cancel chan bool, registers []func(*grpc.Server) error) (int, chan error, error) {
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// Listen on a TCP port, but let the kernel choose a free port for us.
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lis, err := net.Listen("tcp", ":"+strconv.Itoa(port))
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if err != nil {
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return port, nil, errors.Errorf("failed to listen on TCP port ':%v': %v", port, err)
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}
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// Now new up a gRPC server and register any RPC interfaces the caller wants.
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srv := grpc.NewServer()
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for _, register := range registers {
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if err := register(srv); err != nil {
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return port, nil, errors.Errorf("failed to register RPC handler: %v", err)
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}
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}
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reflection.Register(srv) // enable reflection.
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// If the port was 0, look up what port the kernel chosen, by accessing the underlying TCP listener/address.
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if port == 0 {
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tcpl := lis.(*net.TCPListener)
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tcpa := tcpl.Addr().(*net.TCPAddr)
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port = tcpa.Port
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}
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// Now register some signals to gracefully terminate the program upon request.
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sigs := make(chan os.Signal, 1)
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signal.Notify(sigs, syscall.SIGINT, syscall.SIGQUIT, syscall.SIGTERM)
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go func() {
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if cancel == nil {
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// make a channel that will never resolve.
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cancel = make(chan bool)
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}
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for {
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var stop bool
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select {
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case <-sigs:
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stop = true
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case c := <-cancel:
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stop = c
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}
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if stop {
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srv.GracefulStop()
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}
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}
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}()
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// Finally, serve; this returns only once the server shuts down (e.g., due to a signal).
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done := make(chan error)
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go func() {
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if err := srv.Serve(lis); err != nil && !IsBenignCloseErr(err) {
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done <- errors.Errorf("stopped serving: %v", err)
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} else {
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done <- nil // send a signal so caller knows we're done, even though it's nil.
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}
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close(done)
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}()
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return port, done, nil
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}
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