docs: Add examples for callbacks back

cmd/dudirekta-example-callbacks-callee/main.go

@@ -0,0 +1,118 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"sync/atomic"
+	"time"
+
+	"github.com/pojntfx/dudirekta/pkg/rpc"
+)
+
+type local struct {
+	counter int64
+
+	Peers func() map[string]remote
+}
+
+func (s *local) Increment(ctx context.Context, delta int64) (int64, error) {
+	peerID := rpc.GetRemoteID(ctx)
+
+	for candidateIP, peer := range s.Peers() {
+		if candidateIP == peerID {
+			peer.Println(ctx, fmt.Sprintf("Incrementing counter by %v", delta))
+		}
+	}
+
+	return atomic.AddInt64(&s.counter, delta), nil
+}
+
+type remote struct {
+	Println func(ctx context.Context, msg string) error
+}
+
+func main() {
+	addr := flag.String("addr", "localhost:1337", "Listen or remote address")
+	listen := flag.Bool("listen", true, "Whether to allow connecting to peers by listening or dialing")
+
+	flag.Parse()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	service := &local{}
+
+	clients := 0
+	registry := rpc.NewRegistry(
+		service,
+		remote{},
+
+		time.Second*10,
+		ctx,
+		&rpc.Options{
+			ResponseBufferLen: rpc.DefaultResponseBufferLen,
+			OnClientConnect: func(remoteID string) {
+				clients++
+
+				log.Printf("%v clients connected", clients)
+			},
+			OnClientDisconnect: func(remoteID string) {
+				clients--
+
+				log.Printf("%v clients connected", clients)
+			},
+		},
+	)
+	service.Peers = registry.Peers
+
+	if *listen {
+		lis, err := net.Listen("tcp", *addr)
+		if err != nil {
+			panic(err)
+		}
+		defer lis.Close()
+
+		log.Println("Listening on", lis.Addr())
+
+		for {
+			func() {
+				conn, err := lis.Accept()
+				if err != nil {
+					log.Println("could not accept connection, continuing:", err)
+
+					return
+				}
+
+				go func() {
+
+					defer func() {
+						_ = conn.Close()
+
+						if err := recover(); err != nil {
+							log.Printf("Client disconnected with error: %v", err)
+						}
+					}()
+
+					if err := registry.Link(conn); err != nil {
+						panic(err)
+					}
+				}()
+			}()
+		}
+	} else {
+		conn, err := net.Dial("tcp", *addr)
+		if err != nil {
+			panic(err)
+		}
+		defer conn.Close()
+
+		log.Println("Connected to", conn.RemoteAddr())
+
+		if err := registry.Link(conn); err != nil {
+			panic(err)
+		}
+	}
+}

cmd/dudirekta-example-callbacks-caller/main.go

@@ -0,0 +1,150 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"flag"
+	"log"
+	"net"
+	"os"
+	"time"
+
+	"github.com/pojntfx/dudirekta/pkg/rpc"
+)
+
+type local struct{}
+
+func (s *local) Println(ctx context.Context, msg string) error {
+	log.Printf("Printing message for peer with ID %v: %v", rpc.GetRemoteID(ctx), msg)
+
+	return nil
+}
+
+type remote struct {
+	Increment func(ctx context.Context, delta int64) (int64, error)
+}
+
+func main() {
+	addr := flag.String("addr", "localhost:1337", "Listen or remote address")
+	listen := flag.Bool("listen", false, "Whether to allow connecting to peers by listening or dialing")
+
+	flag.Parse()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	clients := 0
+
+	registry := rpc.NewRegistry(
+		&local{},
+		remote{},
+
+		time.Second*10,
+		ctx,
+		&rpc.Options{
+			ResponseBufferLen: rpc.DefaultResponseBufferLen,
+			OnClientConnect: func(remoteID string) {
+				clients++
+
+				log.Printf("%v clients connected", clients)
+			},
+			OnClientDisconnect: func(remoteID string) {
+				clients--
+
+				log.Printf("%v clients connected", clients)
+			},
+		},
+	)
+
+	go func() {
+		log.Println(`Enter one of the following letters followed by <ENTER> to run a function on the remote(s):
+
+- a: Increment remote counter by one
+- b: Decrement remote counter by one`)
+
+		stdin := bufio.NewReader(os.Stdin)
+
+		for {
+			line, err := stdin.ReadString('\n')
+			if err != nil {
+				panic(err)
+			}
+
+			for peerID, peer := range registry.Peers() {
+				log.Println("Calling functions for peer with ID", peerID)
+
+				switch line {
+				case "a\n":
+					new, err := peer.Increment(ctx, 1)
+					if err != nil {
+						log.Println("Got error for Increment func:", err)
+
+						continue
+					}
+
+					log.Println(new)
+				case "b\n":
+					new, err := peer.Increment(ctx, -1)
+					if err != nil {
+						log.Println("Got error for Increment func:", err)
+
+						continue
+					}
+
+					log.Println(new)
+				default:
+					log.Printf("Unknown letter %v, ignoring input", line)
+
+					continue
+				}
+			}
+		}
+	}()
+
+	if *listen {
+		lis, err := net.Listen("tcp", *addr)
+		if err != nil {
+			panic(err)
+		}
+		defer lis.Close()
+
+		log.Println("Listening on", lis.Addr())
+
+		for {
+			func() {
+				conn, err := lis.Accept()
+				if err != nil {
+					log.Println("could not accept connection, continuing:", err)
+
+					return
+				}
+
+				go func() {
+					defer func() {
+						_ = conn.Close()
+
+						if err := recover(); err != nil {
+							log.Printf("Client disconnected with error: %v", err)
+						}
+					}()
+
+					if err := registry.Link(conn); err != nil {
+						panic(err)
+					}
+				}()
+			}()
+		}
+	} else {
+		conn, err := net.Dial("tcp", *addr)
+		if err != nil {
+			panic(err)
+		}
+		defer conn.Close()
+
+		log.Println("Connected to", conn.RemoteAddr())
+
+		if err := registry.Link(conn); err != nil {
+			panic(err)
+		}
+	}
+}

cmd/dudirekta-example-closures-callee/main.go

@@ -62,14 +62,6 @@ func main() {
 		},
 	)
 
-	lis, err := net.Listen("tcp", *addr)
-	if err != nil {
-		panic(err)
-	}
-	defer lis.Close()
-
-	log.Println("Listening on", lis.Addr())
-
 	if *listen {
 		lis, err := net.Listen("tcp", *addr)
 		if err != nil {