From 2046415f9c74b59e548821946128d4616d341e1c Mon Sep 17 00:00:00 2001
From: Lou Knauer <lou.knauer@gmx.de>
Date: Mon, 20 Sep 2021 10:29:55 +0200
Subject: [PATCH] Change out-of-bounds behaviour

---
 debug.go         | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
 lineprotocol.go  |  4 ++--
 memstore.go      |  7 ++++++-
 memstore_test.go | 37 +++++++++++++++++++++++++++++++++--
 4 files changed, 93 insertions(+), 5 deletions(-)
 create mode 100644 debug.go

diff --git a/debug.go b/debug.go
new file mode 100644
index 0000000..a0b5888
--- /dev/null
+++ b/debug.go
@@ -0,0 +1,50 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+)
+
+func (b *buffer) debugDump(w *bufio.Writer) {
+	if b.prev != nil {
+		b.prev.debugDump(w)
+	}
+
+	end := ""
+	if b.next != nil {
+		end = " -> "
+	}
+
+	to := b.start + b.frequency*int64(len(b.data))
+	fmt.Fprintf(w, "buffer(from=%d, len=%d, to=%d)%s", b.start, len(b.data), to, end)
+}
+
+func (l *level) debugDump(w *bufio.Writer, m *MemoryStore, indent string) error {
+	l.lock.RLock()
+	defer l.lock.RUnlock()
+
+	for name, minfo := range m.metrics {
+		b := l.metrics[minfo.offset]
+		if b != nil {
+			fmt.Fprintf(w, "%smetric '%s': ", indent, name)
+			b.debugDump(w)
+			fmt.Fprint(w, "\n")
+		}
+	}
+
+	if l.children != nil {
+		fmt.Fprintf(w, "%schildren:\n", indent)
+		for name, lvl := range l.children {
+			fmt.Fprintf(w, "%s'%s':\n", indent, name)
+			lvl.debugDump(w, m, "\t"+indent)
+		}
+	}
+
+	return nil
+}
+
+func (m *MemoryStore) DebugDump(w *bufio.Writer) error {
+	fmt.Fprintf(w, "MemoryStore:\n")
+	m.root.debugDump(w, m, "  ")
+	return w.Flush()
+}
diff --git a/lineprotocol.go b/lineprotocol.go
index 5b3e246..05140d2 100644
--- a/lineprotocol.go
+++ b/lineprotocol.go
@@ -218,7 +218,7 @@ func ReceiveNats(address string, handleLine func(line *Line), workers int, ctx c
 
 		log.Printf("NATS subscription to 'updates' on '%s' established\n", address)
 
-		_ = <-ctx.Done()
+		<-ctx.Done()
 		err = sub.Unsubscribe()
 	} else {
 		msgs := make(chan *nats.Msg, 16)
@@ -251,7 +251,7 @@ func ReceiveNats(address string, handleLine func(line *Line), workers int, ctx c
 
 		log.Printf("NATS subscription to 'updates' on '%s' established\n", address)
 
-		_ = <-ctx.Done()
+		<-ctx.Done()
 		err = sub.Unsubscribe()
 		close(msgs)
 		wg.Wait()
diff --git a/memstore.go b/memstore.go
index 534a847..1bc1ce5 100644
--- a/memstore.go
+++ b/memstore.go
@@ -107,7 +107,12 @@ func (b *buffer) read(from, to int64, data []Float) ([]Float, int64, int64, erro
 			idx = 0
 		}
 
-		if t < b.start || idx >= len(b.data) {
+		if idx >= len(b.data) {
+			if b.next == nil || to <= b.next.start {
+				break
+			}
+			data[i] += NaN
+		} else if t < b.start {
 			data[i] += NaN
 		} else {
 			data[i] += b.data[idx]
diff --git a/memstore_test.go b/memstore_test.go
index e8a0a94..8967103 100644
--- a/memstore_test.go
+++ b/memstore_test.go
@@ -61,6 +61,39 @@ func TestMemoryStoreBasics(t *testing.T) {
 
 }
 
+func TestMemoryStoreOutOfBounds(t *testing.T) {
+	count := 2000
+	toffset := 1000
+	store := NewMemoryStore(map[string]MetricConfig{
+		"a": {Frequency: 60},
+	})
+
+	for i := 0; i < count; i++ {
+		if err := store.Write([]string{"cluster", "host", "cpu"}, int64(toffset+i*60), []Metric{
+			{Name: "a", Value: Float(i)},
+		}); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	// store.DebugDump(bufio.NewWriter(os.Stdout))
+
+	sel := Selector{{String: "cluster"}, {String: "host"}, {String: "cpu"}}
+	data, from, to, err := store.Read(sel, "a", 500, int64(toffset+count*60+500))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if from != int64(toffset) || to != int64(toffset+count*60) {
+		t.Fatalf("Got %d-%d, expected %d-%d", from, to, toffset, toffset+count*60)
+	}
+
+	if len(data) != count || data[0] != 0 || data[len(data)-1] != Float((count-1)) {
+		t.Fatalf("Wrong data (got: %d, %f, %f, expected: %d, %f, %f)",
+			len(data), data[0], data[len(data)-1], count, 0., Float(count-1))
+	}
+}
+
 func TestMemoryStoreMissingDatapoints(t *testing.T) {
 	count := 3000
 	store := NewMemoryStore(map[string]MetricConfig{
@@ -88,12 +121,12 @@ func TestMemoryStoreMissingDatapoints(t *testing.T) {
 		return
 	}
 
-	if len(adata) != count {
+	if len(adata) != count-2 {
 		t.Error("unexpected len")
 		return
 	}
 
-	for i := 0; i < count; i++ {
+	for i := 0; i < count-2; i++ {
 		if i%3 == 0 {
 			if adata[i] != Float(i) {
 				t.Error("unexpected value")