Fix https_batch deadlock due to golang timer changes

It makes tests hopefully more robus

It also replaces most sleeps with Consistently and Eventually.
It makes the timings more forgiving.

This should make it reliable on weak hardware.

Add functional options pattern to allow test configuration

src/pkg/egress/syslog/https_batch.go

@@ -4,21 +4,35 @@ import (
 	"bytes"
 	"crypto/tls"
 	"log"
+	"sync"
 	"time"
 
 	"code.cloudfoundry.org/go-loggregator/v10/rpc/loggregator_v2"
 	metrics "code.cloudfoundry.org/go-metric-registry"
 	"code.cloudfoundry.org/loggregator-agent-release/src/pkg/egress"
 )
 
-const BATCHSIZE = 256 * 1024
-
 type HTTPSBatchWriter struct {
 	HTTPSWriter
-	msgs         chan []byte
 	batchSize    int
 	sendInterval time.Duration
-	egrMsgCount  float64
+	msgChan      chan []byte
+	quit         chan struct{}
+	wg           sync.WaitGroup
+}
+
+type Option func(*HTTPSBatchWriter)
+
+func WithBatchSize(size int) Option {
+	return func(w *HTTPSBatchWriter) {
+		w.batchSize = size
+	}
+}
+
+func WithSendInterval(interval time.Duration) Option {
+	return func(w *HTTPSBatchWriter) {
+		w.sendInterval = interval
+	}
 }
 
 func NewHTTPSBatchWriter(
@@ -27,10 +41,12 @@ func NewHTTPSBatchWriter(
 	tlsConf *tls.Config,
 	egressMetric metrics.Counter,
 	c *Converter,
+	options ...Option,
 ) egress.WriteCloser {
 	client := httpClient(netConf, tlsConf)
-	binding.URL.Scheme = "https" // reset the scheme for usage to a valid http scheme
-	BatchWriter := &HTTPSBatchWriter{
+	binding.URL.Scheme = "https"
+
+	writer := &HTTPSBatchWriter{
 		HTTPSWriter: HTTPSWriter{
 			url:             binding.URL,
 			appID:           binding.AppID,
@@ -39,60 +55,79 @@ func NewHTTPSBatchWriter(
 			egressMetric:    egressMetric,
 			syslogConverter: c,
 		},
-		batchSize:    BATCHSIZE,
-		sendInterval: 1 * time.Second,
-		egrMsgCount:  0,
-		msgs:         make(chan []byte),
+		batchSize:    256 * 1024,        // Default value
+		sendInterval: 1 * time.Second,   // Default value
+		msgChan:      make(chan []byte), // Buffered channel for messages
+		quit:         make(chan struct{}),
+	}
+
+	for _, opt := range options {
+		opt(writer)
 	}
-	go BatchWriter.startSender()
-	return BatchWriter
+
+	writer.wg.Add(1)
+	go writer.startSender()
+
+	return writer
 }
 
-// Modified Write function
 func (w *HTTPSBatchWriter) Write(env *loggregator_v2.Envelope) error {
 	msgs, err := w.syslogConverter.ToRFC5424(env, w.hostname)
 	if err != nil {
-		log.Printf("Failed to parse syslog, dropping faulty message, err: %s", err)
+		log.Printf("Failed to parse syslog, dropping message, err: %s", err)
 		return nil
 	}
 
 	for _, msg := range msgs {
-		//There is no correct way of implementing error based retries in the current architecture.
-		//Retries for https-batching will be implemented at a later point in time.
-		w.msgs <- msg
+		w.msgChan <- msg
 	}
+
 	return nil
 }
 
 func (w *HTTPSBatchWriter) startSender() {
-	t := time.NewTimer(w.sendInterval)
+	defer w.wg.Done()
+
+	ticker := time.NewTicker(w.sendInterval)
+	defer ticker.Stop()
 
 	var msgBatch bytes.Buffer
 	var msgCount float64
-	reset := func() {
-		msgBatch.Reset()
-		msgCount = 0
-		t.Reset(w.sendInterval)
+
+	sendBatch := func() {
+		if msgBatch.Len() > 0 {
+			w.sendHttpRequest(msgBatch.Bytes(), msgCount) // nolint:errcheck
+			msgBatch.Reset()
+			msgCount = 0
+		}
 	}
+
 	for {
 		select {
-		case msg := <-w.msgs:
-			length, buffer_err := msgBatch.Write(msg)
-			if buffer_err != nil {
-				log.Printf("Failed to write to buffer, dropping buffer of size %d , err: %s", length, buffer_err)
-				reset()
+		case msg := <-w.msgChan:
+			_, err := msgBatch.Write(msg)
+			if err != nil {
+				log.Printf("Failed to write to buffer, dropping buffer of size %d , err: %s", msgBatch.Len(), err)
+				msgBatch.Reset()
+				msgCount = 0
 			} else {
 				msgCount++
-				if length >= w.batchSize {
-					w.sendHttpRequest(msgBatch.Bytes(), msgCount) //nolint:errcheck
-					reset()
+				if msgBatch.Len() >= w.batchSize {
+					sendBatch()
 				}
 			}
-		case <-t.C:
-			if msgBatch.Len() > 0 {
-				w.sendHttpRequest(msgBatch.Bytes(), msgCount) //nolint:errcheck
-				reset()
-			}
+		case <-ticker.C:
+			sendBatch()
+		case <-w.quit:
+			sendBatch()
+			return
 		}
 	}
 }
+
+func (w *HTTPSBatchWriter) Close() error {
+	close(w.quit)
+	w.wg.Wait() // Ensure sender finishes processing before closing
+	close(w.msgChan)
+	return nil
+}

src/pkg/egress/syslog/https_batch_test.go

@@ -17,7 +17,14 @@ import (
 	. "github.com/onsi/gomega"
 )
 
-var string_to_1024_chars = "saljdflajsdssdfsdfljkfkajafjajlköflkjöjaklgljksdjlakljkflkjweljklkwjejlkfekljwlkjefjklwjklsdajkljklwerlkaskldgjksakjekjwrjkljasdjkgfkljwejklrkjlklasdkjlsadjlfjlkadfljkajklsdfjklslkdfjkllkjasdjkflsdlakfjklasldfkjlasdjfkjlsadlfjklaljsafjlslkjawjklerkjljklasjkdfjklwerjljalsdjkflwerjlkwejlkarjklalkklfsdjlfhkjsdfkhsewhkjjasdjfkhwkejrkjahjefkhkasdjhfkashfkjwehfkksadfjaskfkhjdshjfhewkjhasdfjdajskfjwehkfajkankaskjdfasdjhfkkjhjjkasdfjhkjahksdf"
+var stringTo256Chars string
+
+func init() {
+	//With the rest of the syslog, this results in a syslogenvelope of the size 400
+	for i := 0; i < 256; i++ {
+		stringTo256Chars += "a"
+	}
+}
 
 var _ = Describe("HTTPS_batch", func() {
 	var (
@@ -30,10 +37,10 @@ var _ = Describe("HTTPS_batch", func() {
 		b      *syslog.URLBinding
 		writer egress.WriteCloser
 	)
-	string_to_1024_chars += string_to_1024_chars
 
 	BeforeEach(func() {
 		drain = newBatchMockDrain(200)
+		drain.Reset()
 		b = buildURLBinding(
 			drain.URL,
 			"test-app-id",
@@ -45,6 +52,8 @@ var _ = Describe("HTTPS_batch", func() {
 			skipSSLTLSConfig,
 			&metricsHelpers.SpyMetric{},
 			c,
+			syslog.WithBatchSize(5000),
+			syslog.WithSendInterval(100*time.Millisecond),
 		)
 	})
 
@@ -53,7 +62,7 @@ var _ = Describe("HTTPS_batch", func() {
 		Expect(writer.Write(env1)).To(Succeed())
 		env2 := buildLogEnvelope("APP", "2", "message 2", loggregator_v2.Log_OUT)
 		Expect(writer.Write(env2)).To(Succeed())
-		time.Sleep(1050 * time.Millisecond)
+		time.Sleep(150 * time.Millisecond)
 
 		Expect(drain.getMessagesSize()).Should(Equal(2))
 		expected := &rfc5424.Message{
@@ -83,24 +92,36 @@ var _ = Describe("HTTPS_batch", func() {
 	})
 
 	It("test batch dispatching with all logs in a given timeframe", func() {
-		env1 := buildLogEnvelope("APP", "1", "string to get log to 1024 characters:"+string_to_1024_chars, loggregator_v2.Log_OUT)
+		env1 := buildLogEnvelope("APP", "1", "string to get log to 400 characters:"+stringTo256Chars, loggregator_v2.Log_OUT)
 		for i := 0; i < 10; i++ {
 			Expect(writer.Write(env1)).To(Succeed())
-			time.Sleep(99 * time.Millisecond)
 		}
-		Expect(drain.getMessagesSize()).Should(Equal(0))
-		time.Sleep(100 * time.Millisecond)
-		Expect(drain.getMessagesSize()).Should(Equal(10))
+		Expect(drain.getMessagesSize()).To(Equal(0))
+		Eventually(drain.getMessagesSize, 180*time.Millisecond).Should(Equal(10))
 	})
 
-	It("probabilistic test for race condition", func() {
-		env1 := buildLogEnvelope("APP", "1", "string to get log to 1024 characters:"+string_to_1024_chars, loggregator_v2.Log_OUT)
-		for i := 0; i < 10; i++ {
+	It("test dispatching for batches before timewindow is finished", func() {
+		// One envelope has the size of 400byte
+		env1 := buildLogEnvelope("APP", "1", "string to get log to 400 characters:"+stringTo256Chars, loggregator_v2.Log_OUT)
+
+		for i := 0; i < 20; i++ {
 			Expect(writer.Write(env1)).To(Succeed())
-			time.Sleep(99 * time.Millisecond)
 		}
-		time.Sleep(100 * time.Millisecond)
-		Expect(drain.getMessagesSize()).Should(Equal(10))
+		// DefaultBatchSize = 5000byte, 12 * 400byte = 4800byte, 13 * 400byte = 5200byte
+		// -> The batch will trigger after 13 messages, and this is not a direct hit to prevent inconsistencies.
+		Eventually(drain.getMessagesSize, 50*time.Millisecond).Should(Equal(13))
+		Eventually(drain.getMessagesSize, 120*time.Millisecond).Should(Equal(20))
+	})
+
+	It("test for hanging after some ticks", func() {
+		// This test will not succeed on the timer based implementation,
+		// it works fine with a ticker based implementation.
+		env1 := buildLogEnvelope("APP", "1", "only a short test message", loggregator_v2.Log_OUT)
+		for i := 0; i < 5; i++ {
+			Expect(writer.Write(env1)).To(Succeed())
+			time.Sleep(220 * time.Millisecond) // this sleeps at least 2 ticks, to trigger once without events
+		}
+		Eventually(drain.getMessagesSize, 120*time.Millisecond).Should(Equal(5))
 	})
 })
 
@@ -112,8 +133,6 @@ func newBatchMockDrain(status int) *SpyDrain {
 		Expect(err).ToNot(HaveOccurred())
 		defer r.Body.Close()
 
-		println(body)
-
 		message := &rfc5424.Message{}
 
 		messages := bytes.SplitAfter(body, []byte("\n"))

src/pkg/egress/syslog/https_test.go

@@ -251,6 +251,11 @@ type SpyDrain struct {
 	headers  []http.Header
 }
 
+func (d *SpyDrain) Reset() {
+	d.messages = nil
+	d.headers = nil
+}
+
 func (d *SpyDrain) appendMessage(message *rfc5424.Message) {
 	d.mu.Lock()
 	defer d.mu.Unlock()