Let the client send health checks periodically

cmd/clientsim/main.go

@@ -20,16 +20,16 @@ limitations under the License.
 package main
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"sync"
 	"time"
 
+	"git.cacert.org/cacert-gosigner/pkg/messages"
 	"github.com/justincpresley/go-cobs"
 	"github.com/shamaton/msgpackgen/msgpack"
-
-	"git.cacert.org/cacert-gosigner/pkg/messages"
 )
 
 const cobsDelimiter = 0x00
@@ -37,108 +37,157 @@ const cobsDelimiter = 0x00
 var cobsConfig = cobs.Config{SpecialByte: cobsDelimiter, Delimiter: true, EndingSave: true}
 
 func main() {
+	errorLog := log.New(os.Stderr, "", log.LstdFlags)
+
+	sim := &clientSimulator{
+		errorLog: errorLog,
+	}
+
+	err := sim.Run()
+	if err != nil {
+		errorLog.Printf("simulator returned an error: %v", err)
+	}
+}
+
+type clientSimulator struct {
+	errorLog  *log.Logger
+	commands  chan messages.Command
+	responses chan []byte
+}
+
+func (c *clientSimulator) writeTestCommands(ctx context.Context) error {
+	messages.RegisterGeneratedResolver()
+
+	const healthInterval = 10 * time.Second
+
+	timer := time.NewTimer(healthInterval)
+
+	for {
+		select {
+		case <-ctx.Done():
+			_ = timer.Stop()
+
+			return nil
+		case <-timer.C:
+			c.commands <- messages.Command{
+				Code:      messages.CmdHealth,
+				TimeStamp: time.Now().UTC(),
+			}
+
+			timer.Reset(healthInterval)
+		}
+	}
+}
+
+func (c *clientSimulator) handleInput(ctx context.Context) error {
 	const (
 		bufferSize   = 1024 * 1024
 		readInterval = 50 * time.Millisecond
 	)
 
-	errors := make(chan error)
+	buf := make([]byte, bufferSize)
 
-	errorLog := log.New(os.Stderr, "", log.LstdFlags)
+	for {
+		select {
+		case <-ctx.Done():
+			return nil
+		default:
+			count, err := os.Stdin.Read(buf)
+			if err != nil {
+				return err
+			}
+
+			if count == 0 {
+				time.Sleep(readInterval)
+
+				continue
+			}
+
+			data := buf[:count]
+
+			err = cobs.Verify(data, cobsConfig)
+			if err != nil {
+				return err
+			}
+
+			c.responses <- cobs.Decode(data, cobsConfig)
+		}
+	}
+}
+
+func (c *clientSimulator) handleCommands(ctx context.Context) error {
+	for {
+		select {
+		case command := <-c.commands:
+			commandBytes, err := msgpack.Marshal(command)
+			if err != nil {
+				return fmt.Errorf("could not marshal command bytes: %w", err)
+			}
+
+			_, err = os.Stdout.Write(cobs.Encode(commandBytes, cobsConfig))
+			if err != nil {
+				return fmt.Errorf("write failed: %w", err)
+			}
+
+			responseBytes := <-c.responses
+
+			var response messages.Response
+
+			err = msgpack.Unmarshal(responseBytes, &response)
+			if err != nil {
+				return fmt.Errorf("could not unmarshal msgpack data: %w", err)
+			}
+
+			c.errorLog.Printf("received response: %+v", response)
+		case <-ctx.Done():
+			return nil
+		}
+	}
+}
+
+func (c *clientSimulator) Run() error {
+	ctx, cancel := context.WithCancel(context.Background())
+
+	c.commands = make(chan messages.Command)
+	c.responses = make(chan []byte)
 
 	wg := sync.WaitGroup{}
-	wg.Add(1)
+	wg.Add(2)
 
-	done := make(chan struct{})
+	var inputError, commandError error
-	frame := make(chan []byte)
 
-	go func(done chan struct{}) {
+	go func(inputErr error) {
-		buf := make([]byte, bufferSize)
+		inputError = c.handleInput(ctx)
 
-		for {
+		cancel()
-			select {
-			case <-done:
-				wg.Done()
 
-				return
+		wg.Done()
+	}(inputError)
 
-			default:
+	go func(commandErr error) {
-				count, err := os.Stdin.Read(buf)
+		commandErr = c.handleCommands(ctx)
-				if err != nil {
-					errors <- err
 
-					wg.Done()
+		cancel()
 
-					return
+		wg.Done()
-				}
+	}(commandError)
 
-				if count == 0 {
+	var result error
-					time.Sleep(readInterval)
 
-					continue
+	if err := c.writeTestCommands(ctx); err != nil {
-				}
+		c.errorLog.Printf("test commands failed: %v", err)
-
-				data := buf[:count]
-
-				err = cobs.Verify(data, cobsConfig)
-				if err != nil {
-					errors <- err
-
-					wg.Done()
-
-					return
-				}
-
-				frame <- cobs.Decode(data, cobsConfig)
-			}
-		}
-	}(done)
-
-	err := writeTestCommands(frame, errorLog)
-	if err != nil {
-		errorLog.Printf("could not write test commands")
-	}
-
-	err = <-errors
-	if err != nil {
-		errorLog.Printf("error: %v", err)
 	}
 
+	cancel()
 	wg.Wait()
-}
 
-func writeTestCommands(responses chan []byte, errorLog *log.Logger) error {
+	if inputError != nil {
-	messages.RegisterGeneratedResolver()
+		c.errorLog.Printf("reading input failed: %v", inputError)
-
-	commands := []messages.Command{
-		{
-			Code:      messages.CmdHealth,
-			TimeStamp: time.Now().UTC(),
-		},
 	}
 
-	for _, command := range commands {
+	if commandError != nil {
-		commandBytes, err := msgpack.Marshal(command)
+		c.errorLog.Printf("sending commands failed: %v", commandError)
-		if err != nil {
-			return fmt.Errorf("could not marshal command bytes: %w", err)
-		}
-
-		_, err = os.Stdout.Write(cobs.Encode(commandBytes, cobsConfig))
-		if err != nil {
-			return fmt.Errorf("write failed: %w", err)
-		}
-
-		responseBytes := <-responses
-
-		var response messages.Response
-
-		err = msgpack.Unmarshal(responseBytes, &response)
-		if err != nil {
-			return fmt.Errorf("could not unmarshal msgpack data: %w", err)
-		}
-
-		errorLog.Printf("received response: %+v", response)
 	}
 
-	return nil
+	return result
 }