From 275d6672574ffb8f0294375e4edff8599b5d9d28 Mon Sep 17 00:00:00 2001
From: Paul Lorenz <paul.lorenz@netfoundry.io>
Date: Tue, 24 Sep 2024 21:29:09 -0400
Subject: [PATCH] Add ReadAdapter type. Fixes #144

---
 heartbeater.go  |   3 +
 read_adapter.go | 145 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 148 insertions(+)
 create mode 100644 read_adapter.go

diff --git a/heartbeater.go b/heartbeater.go
index 1294e6b..a827bd0 100644
--- a/heartbeater.go
+++ b/heartbeater.go
@@ -135,6 +135,9 @@ func (self *heartbeater) Rx(m *Message, _ Channel) {
 }
 
 func (self *heartbeater) Tx(m *Message, _ Channel) {
+	if m.ContentType == ContentTypeRaw {
+		return
+	}
 	now := time.Now().UnixNano()
 	if now-self.lastHeartbeatTx > self.heartBeatIntervalNs {
 		m.PutUint64Header(HeartbeatHeader, uint64(now))
diff --git a/read_adapter.go b/read_adapter.go
new file mode 100644
index 0000000..cfac18b
--- /dev/null
+++ b/read_adapter.go
@@ -0,0 +1,145 @@
+package channel
+
+import (
+	"github.com/michaelquigley/pfxlog"
+	"github.com/openziti/foundation/v2/concurrenz"
+	"github.com/pkg/errors"
+	"io"
+	"sync/atomic"
+	"time"
+)
+
+var ErrClosed = errors.New("channel closed")
+
+type ReadTimout struct{}
+
+func (r ReadTimout) Error() string {
+	return "read timed out"
+}
+
+func (r ReadTimout) Timeout() bool {
+	return true
+}
+
+func (r ReadTimout) Temporary() bool {
+	return true
+}
+
+func NewReadAdapter(label string, channelDepth int) *ReadAdapter {
+	return &ReadAdapter{
+		label:          label,
+		ch:             make(chan []byte, channelDepth),
+		closeNotify:    make(chan struct{}),
+		deadlineNotify: make(chan struct{}),
+	}
+}
+
+type ReadAdapter struct {
+	label          string
+	ch             chan []byte
+	closeNotify    chan struct{}
+	deadlineNotify chan struct{}
+	deadline       concurrenz.AtomicValue[time.Time]
+	closed         atomic.Bool
+	readInProgress atomic.Bool
+	leftover       []byte
+}
+
+func (self *ReadAdapter) PushData(data []byte) error {
+	select {
+	case self.ch <- data:
+		return nil
+	case <-self.closeNotify:
+		return ErrClosed
+	}
+}
+
+func (self *ReadAdapter) SetReadDeadline(deadline time.Time) error {
+	self.deadline.Store(deadline)
+	if self.readInProgress.Load() {
+		select {
+		case self.deadlineNotify <- struct{}{}:
+		case <-time.After(5 * time.Millisecond):
+		}
+	} else {
+		select {
+		case self.deadlineNotify <- struct{}{}:
+		default:
+		}
+	}
+	return nil
+}
+
+func (self *ReadAdapter) GetNext() ([]byte, error) {
+	self.readInProgress.Store(true)
+	defer self.readInProgress.Store(false)
+
+	for {
+		deadline := self.deadline.Load()
+
+		var timeoutCh <-chan time.Time
+
+		if !deadline.IsZero() {
+			timeoutCh = time.After(time.Until(deadline))
+		}
+
+		select {
+		case data := <-self.ch:
+			return data, nil
+		case <-self.closeNotify:
+			// If we're closed, return any buffered values, otherwise return nil
+			select {
+			case data := <-self.ch:
+				return data, nil
+			default:
+				return nil, ErrClosed
+			}
+		case <-self.deadlineNotify:
+			continue
+		case <-timeoutCh:
+			// If we're timing out, return any buffered values, otherwise return nil
+			select {
+			case data := <-self.ch:
+				return data, nil
+			default:
+				return nil, &ReadTimout{}
+			}
+		}
+	}
+}
+
+func (self *ReadAdapter) Read(b []byte) (n int, err error) {
+	log := pfxlog.Logger().WithField("label", self.label)
+	if self.closed.Load() {
+		return 0, io.EOF
+	}
+
+	log.Tracef("read buffer = %d bytes", len(b))
+	if len(self.leftover) > 0 {
+		log.Tracef("found %d leftover bytes", len(self.leftover))
+		n = copy(b, self.leftover)
+		self.leftover = self.leftover[n:]
+		return n, nil
+	}
+
+	for {
+		d, err := self.GetNext()
+		if err != nil {
+			return 0, err
+		}
+		log.Tracef("got buffer from sequencer %d bytes", len(d))
+
+		n = copy(b, d)
+		self.leftover = d[n:]
+
+		log.Tracef("saving %d bytes for leftover", len(self.leftover))
+		log.Tracef("reading %v bytes", n)
+		return n, nil
+	}
+}
+
+func (self *ReadAdapter) Close() {
+	if self.closed.CompareAndSwap(false, true) {
+		close(self.closeNotify)
+	}
+}