Initial checkin

2025-10-31 09:05:06 +01:00 · 2021-06-09 06:03:31 +02:00
parent a59049d24e
commit a85b210096
10 changed files with 921 additions and 2 deletions
--- a/README.md
+++ b/README.md
@@ -1,2 +1,3 @@
-# cc-metric-store
-A simple in-memory metric store
+# ClusterCockpit Metric Store
+
+FileStore is only a code fragment. To test the memoryStore move away the fileStore and run go test.
--- a/TODO.md
+++ b/TODO.md
@@ -0,0 +1,3 @@
+# Missing Testcases
+
+
--- a/config.json
+++ b/config.json
@@ -0,0 +1,15 @@
+{
+    "root": "/home/jan/bla",
+    [
+        {
+            "class": "N",
+            "frequency": 60,
+            "metrics": ["flops_any", "mem_bw"]
+        },
+        {
+            "class": "C",
+            "frequency": 30,
+            "metrics": ["cpi", "flops_any"]
+        }
+    ]
+}
--- a/fileStore.go
+++ b/fileStore.go
@@ -0,0 +1,65 @@
+package main
+
+import (
+	"log"
+	"os"
+)
+
+//MetricFile holds the state for a metric store file.
+//It does not export any variable.
+type FileStore struct {
+	metrics    map[string]int
+	numMetrics int
+	size       int64
+	root       string
+}
+
+func getFileName(tp string, ts string, start int64) string {
+
+}
+
+func newFileStore(root string, size int64, o []string) {
+	var f FileStore
+	f.root = root
+	f.size = size
+
+	for i, name := range o {
+		f.metrics[name] = i * f.size * 8
+	}
+}
+
+func openFile(fp string, hd *FileHeader) (f *File, err error) {
+	f, err = os.OpenFile(file, os.O_WRONLY, 0644)
+
+	if err != nil {
+		return f, err
+	}
+
+}
+
+func createFile(fp string) (f *File, err error) {
+	f, err = os.Create(fp)
+
+	if err != nil {
+		return f, err
+	}
+
+}
+
+func getFileHandle(file string, start int64) (f *File, err error) {
+	f, err = os.OpenFile(file, os.O_CREATE|os.O_WRONLY, 0644)
+
+	if err != nil {
+		return f, err
+	}
+
+	if _, err := f.Write([]byte("appended some data\n")); err != nil {
+		f.Close() // ignore error; Write error takes precedence
+		log.Fatal(err)
+	}
+	if err := f.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	return f
+}
--- a/fileStore_test.go
+++ b/fileStore_test.go
@@ -0,0 +1,7 @@
+package main
+
+import "testing"
+
+func TestAddMetrics(t *testing.T) {
+
+}
--- a/go.mod
+++ b/go.mod
@@ -0,0 +1,9 @@
+module github.com/ClusterCockpit/cc-metric-store
+
+go 1.16
+
+require (
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/nats-io/nats-server/v2 v2.2.6 // indirect
+	github.com/nats-io/nats.go v1.11.0
+)
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,57 @@
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--- a/memoryStore.go
+++ b/memoryStore.go
@@ -0,0 +1,171 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+type storeBuffer struct {
+	store []float64
+	start int64
+}
+
+type buffer struct {
+	current *storeBuffer
+	next    *storeBuffer
+}
+
+//MemoryStore holds the state for a metric memory store.
+//It does not export any variable.
+type MemoryStore struct {
+	containers map[string]*buffer
+	offsets    map[string]int
+	frequency  int
+	numSlots   int
+	numMetrics int
+}
+
+func initBuffer(b *storeBuffer) {
+	for i := 0; i < len(b.store); i++ {
+		b.store[i] = math.NaN()
+	}
+}
+
+func allocateBuffer(ts int64, size int) *buffer {
+	b := new(buffer)
+	s := make([]float64, size)
+	b.current = &storeBuffer{s, ts}
+	initBuffer(b.current)
+
+	s = make([]float64, size)
+	b.next = &storeBuffer{s, 0}
+	initBuffer(b.next)
+	return b
+}
+
+func switchBuffers(m *MemoryStore, b *buffer) {
+	initBuffer(b.next)
+	b.current, b.next = b.next, b.current
+	b.current.start = b.next.start + int64(m.numSlots*m.frequency)
+}
+
+func newMemoryStore(o []string, n int, f int) *MemoryStore {
+	var m MemoryStore
+	m.frequency = f
+	m.numSlots = n
+	m.containers = make(map[string]*buffer)
+	m.offsets = make(map[string]int)
+
+	for i, name := range o {
+		m.offsets[name] = i
+	}
+
+	m.numMetrics = len(o)
+
+	return &m
+}
+
+// AddMetrics writes metrics to the memoryStore for entity key
+// at unix epoch time ts. The unit of ts is seconds.
+// An error is returned if ts is out of bounds of MemoryStore.
+func (m *MemoryStore) AddMetrics(
+	key string,
+	ts int64,
+	metrics []Metric) error {
+
+	b, ok := m.containers[key]
+
+	if !ok {
+		//Key does not exist. Allocate new buffer.
+		m.containers[key] = allocateBuffer(ts, m.numMetrics*m.numSlots)
+		b = m.containers[key]
+	}
+
+	index := int(ts-b.current.start) / m.frequency
+
+	if index < 0 || index >= 2*m.numSlots {
+		return fmt.Errorf("ts %d out of bounds", ts)
+	}
+
+	if index >= m.numSlots {
+		//Index exceeds buffer length. Switch buffers.
+		switchBuffers(m, b)
+		index = int(ts-b.current.start) / m.frequency
+	}
+
+	s := b.current.store
+
+	for _, metric := range metrics {
+		s[m.offsets[metric.Name]*m.numSlots+index] = metric.Value
+	}
+
+	return nil
+}
+
+// GetMetric returns a slize with metric values for timerange
+// and entity key. Returns an error if key does not exist,
+// stop is before start or start is in the future.
+func (m *MemoryStore) GetMetric(
+	key string,
+	metric string,
+	from int64,
+	to int64) ([]float64, int64, error) {
+
+	b, ok := m.containers[key]
+
+	if !ok {
+		return nil, 0, fmt.Errorf("key %s does not exist", key)
+	}
+
+	if to <= from {
+		return nil, 0, fmt.Errorf("invalid duration %d - %d", from, to)
+	}
+
+	if from > b.current.start+int64(m.numSlots*m.frequency) {
+		return nil, 0, fmt.Errorf("from %d out of bounds", from)
+	}
+
+	if to < b.next.start {
+		return nil, 0, fmt.Errorf("to %d out of bounds", to)
+	}
+
+	var values1, values2 []float64
+	offset := m.offsets[metric]
+	valuesFrom := from
+
+	if from < b.current.start {
+
+		var start, stop = 0, m.numSlots
+
+		if from > b.next.start {
+			start = int(from-b.next.start) / m.frequency
+		} else {
+			valuesFrom = b.next.start
+		}
+
+		if to < b.current.start {
+			stop = int(to-b.next.start) / m.frequency
+		}
+
+		// fmt.Println("NEXT", start, stop)
+		values1 = b.next.store[offset+start : offset+stop]
+	}
+
+	if to >= b.current.start {
+
+		var start, stop = 0, m.numSlots
+
+		if from > b.current.start {
+			start = int(from-b.current.start) / m.frequency
+		}
+
+		if to <= b.current.start+int64(m.numSlots*m.frequency) {
+			stop = int(to-b.current.start) / m.frequency
+		}
+
+		// fmt.Println("CURRENT", start, stop, b.current.start)
+		values2 = b.current.store[offset+start : offset+stop]
+	}
+
+	return append(values1, values2...), valuesFrom, nil
+}
--- a/memoryStore_test.go
+++ b/memoryStore_test.go
@@ -0,0 +1,502 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"math"
+	"testing"
+)
+
+var testMetrics [][]Metric = [][]Metric{
+	{{"flops", 100.5}, {"mem_bw", 2088.67}},
+	{{"flops", 180.5}, {"mem_bw", 4078.32}, {"mem_capacity", 1020}},
+	{{"flops", 980.5}, {"mem_bw", 9078.32}, {"mem_capacity", 5010}},
+	{{"flops", 940.5}, {"mem_bw", 9278.32}, {"mem_capacity", 6010}},
+	{{"flops", 930.5}, {"mem_bw", 9378.32}, {"mem_capacity", 7010}},
+	{{"flops", 980.5}, {"mem_bw", 9478.32}, {"mem_capacity", 8010}},
+	{{"flops", 980.5}, {"mem_bw", 9478.32}, {"mem_capacity", 8010}},
+	{{"flops", 980.5}, {"mem_bw", 9478.32}, {"mem_capacity", 8010}},
+	{{"flops", 970.5}, {"mem_bw", 9178.32}, {"mem_capacity", 2010}},
+	{{"flops", 970.5}, {"mem_bw", 9178.32}, {"mem_capacity", 2010}}}
+
+var testMetricsAlt [][]Metric = [][]Metric{
+	{{"flops", 120.5}, {"mem_bw", 2080.67}},
+	{{"flops", 130.5}, {"mem_bw", 4071.32}, {"mem_capacity", 1120}},
+	{{"flops", 940.5}, {"mem_bw", 9072.32}, {"mem_capacity", 5210}},
+	{{"flops", 950.5}, {"mem_bw", 9273.32}, {"mem_capacity", 6310}},
+	{{"flops", 960.5}, {"mem_bw", 9374.32}, {"mem_capacity", 7410}},
+	{{"flops", 970.5}, {"mem_bw", 9475.32}, {"mem_capacity", 8510}},
+	{{"flops", 990.5}, {"mem_bw", 9476.32}, {"mem_capacity", 8610}},
+	{{"flops", 910.5}, {"mem_bw", 9477.32}, {"mem_capacity", 8710}},
+	{{"flops", 920.5}, {"mem_bw", 9178.32}, {"mem_capacity", 2810}},
+	{{"flops", 930.5}, {"mem_bw", 9179.32}, {"mem_capacity", 2910}}}
+
+func dumpStoreBuffer(s *storeBuffer) {
+	log.Printf("Start TS %d\n", s.start)
+	ctr := 0
+
+	for _, val := range s.store {
+		fmt.Printf("%f\t", val)
+		ctr++
+
+		if ctr == 10 {
+			fmt.Printf("\n")
+			ctr = 0
+		}
+	}
+}
+
+func printMemStore(m *MemoryStore) {
+	log.Println("########################")
+	log.Printf("Frequency %d, Metrics %d Slots %d\n",
+		m.frequency, m.numMetrics, m.numSlots)
+	log.Println("##Offsets")
+	for key, val := range m.offsets {
+		log.Printf("\t%s = %d\n", key, val)
+	}
+	log.Println("##Containers")
+	for key, c := range m.containers {
+		log.Printf("ID %s\n", key)
+		log.Println("###current")
+		dumpStoreBuffer(c.current)
+		log.Println("###next")
+		dumpStoreBuffer(c.next)
+	}
+	log.Println("########################")
+}
+
+//############################
+//#### Whitebox tests ########
+//############################
+func TestAddMetricSimple(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+	// printMemStore(m)
+
+	m.AddMetrics(key, 1584022800, testMetrics[0])
+	m.AddMetrics(key, 1584022890, testMetrics[1])
+
+	want := testMetrics[0][0].Value
+	got := m.containers[key].current.store[0]
+	if got != want {
+		t.Errorf("Want %f got %f\n", want, got)
+	}
+
+	want = testMetrics[1][2].Value
+	got = m.containers[key].current.store[21]
+	if got != want {
+		t.Errorf("Want %f got %f\n", want, got)
+	}
+	// printMemStore(m)
+}
+
+func TestAddMetricReplace(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+	// printMemStore(m)
+
+	m.AddMetrics(key, 1584022800, testMetrics[0])
+	m.AddMetrics(key, 1584022800, testMetrics[1])
+
+	want := testMetrics[1][0].Value
+	got := m.containers[key].current.store[0]
+	if got != want {
+		t.Errorf("Want %f got %f\n", want, got)
+	}
+
+	m.AddMetrics(key, 1584022850, testMetrics[0])
+	want = testMetrics[0][0].Value
+	got = m.containers[key].current.store[0]
+	if got != want {
+		t.Errorf("Want %f got %f\n", want, got)
+	}
+
+	m.AddMetrics(key, 1584022860, testMetrics[1])
+	want = testMetrics[0][0].Value
+	got = m.containers[key].current.store[0]
+	if got != want {
+		t.Errorf("Want %f got %f\n", want, got)
+	}
+	// printMemStore(m)
+}
+
+func TestAddMetricSwitch(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+	// printMemStore(m)
+
+	m.AddMetrics(key, 1584023000, testMetrics[0])
+	m.AddMetrics(key, 1584023580, testMetrics[1])
+
+	want := testMetrics[1][2].Value
+	got := m.containers[key].current.store[29]
+	if got != want {
+		t.Errorf("Want %f got %f\n", want, got)
+	}
+
+	m.AddMetrics(key, 1584023600, testMetrics[2])
+	want = testMetrics[2][2].Value
+	got = m.containers[key].current.store[20]
+	if got != want {
+		t.Errorf("Want %f got %f\n", want, got)
+	}
+
+	// printMemStore(m)
+}
+
+//############################
+//#### Blackbox tests ########
+//############################
+
+func TestAddMetricOutOfBounds(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 30, 60)
+
+	err := m.AddMetrics(key, 1584023000, testMetrics[0])
+	if err != nil {
+		t.Errorf("Got error 1584023000\n")
+	}
+	err = m.AddMetrics(key, 1584026600, testMetrics[0])
+	if err == nil {
+		t.Errorf("Got no error 1584026600\n")
+	}
+	err = m.AddMetrics(key, 1584021580, testMetrics[1])
+	if err == nil {
+		t.Errorf("Got no error 1584021580\n")
+	}
+	err = m.AddMetrics(key, 1584024580, testMetrics[1])
+	if err != nil {
+		t.Errorf("Got error 1584024580\n")
+	}
+	err = m.AddMetrics(key, 1584091580, testMetrics[1])
+	if err == nil {
+		t.Errorf("Got no error 1584091580\n")
+	}
+	err = m.AddMetrics(key, 1584024780, testMetrics[0])
+	if err != nil {
+		t.Errorf("Got error 1584024780\n")
+	}
+}
+
+func TestGetMetricPlainCurrent(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+
+	// printMemStore(m)
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584023000, 1584023560)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023000 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 9 {
+		t.Errorf("Want 9. Got %d\n", len(val))
+	}
+	if val[0] != 100.5 {
+		t.Errorf("Want 100.5 Got %f\n", val[0])
+	}
+	if val[8] != 970.5 {
+		t.Errorf("Want 970.5 Got %f\n", val[9])
+	}
+}
+
+func TestGetMetricPlainNext(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584023000, 1584023560)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023000 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 9 {
+		t.Errorf("Want 9. Got %d\n", len(val))
+	}
+	if val[0] != 100.5 {
+		t.Errorf("Want 100.5 Got %f\n", val[0])
+	}
+	if val[8] != 970.5 {
+		t.Errorf("Want 970.5 Got %f\n", val[9])
+	}
+}
+
+func TestGetMetricGap(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*120), testMetrics[i])
+	}
+
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584023000, 1584023600)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023000 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 10 {
+		t.Errorf("Want 10. Got %d\n", len(val))
+	}
+	if val[0] != 100.5 {
+		t.Errorf("Want 100.5 Got %f\n", val[0])
+	}
+	if !math.IsNaN(val[1]) {
+		t.Errorf("Want NaN Got %f\n", val[1])
+	}
+	if val[0] != 100.5 {
+		t.Errorf("Want 100.5 Got %f\n", val[0])
+	}
+
+	// fmt.Println(val)
+}
+
+func TestGetMetricSplit(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584023200, 1584023860)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023200 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 11 {
+		t.Errorf("Want 11. Got %d\n", len(val))
+	}
+	if val[0] != 940.5 {
+		t.Errorf("Want 940.5 Got %f\n", val[0])
+	}
+	if val[10] != 950.5 {
+		t.Errorf("Want 950.5 Got %f\n", val[0])
+	}
+}
+
+func TestGetMetricExceedNext(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584022800, 1584023400)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023000 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 6 {
+		t.Errorf("Want 6. Got %d\n", len(val))
+	}
+	if val[0] != 100.5 {
+		t.Errorf("Want 100.5 Got %f\n", val[0])
+	}
+	if val[5] != 980.5 {
+		t.Errorf("Want 980.5 Got %f\n", val[5])
+	}
+}
+
+func TestGetMetricExceedNextSplit(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584022800, 1584023900)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023000 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 15 {
+		t.Errorf("Want 14. Got %d\n", len(val))
+	}
+	if val[0] != 100.5 {
+		t.Errorf("Want 100.5 Got %f\n", val[0])
+	}
+	if val[14] != 960.5 {
+		t.Errorf("Want 960.5 Got %f\n", val[13])
+	}
+}
+
+func TestGetMetricExceedCurrent(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584023800, 1584027900)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023800 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 7 {
+		t.Errorf("Want 6. Got %d\n", len(val))
+	}
+	if val[0] != 950.5 {
+		t.Errorf("Want 950.5 Got %f\n", val[0])
+	}
+	if val[6] != 930.5 {
+		t.Errorf("Want 930.5 Got %f\n", val[5])
+	}
+}
+
+func TestGetMetricExceedCurrentSplit(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584023120, 1584027900)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023120 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 18 {
+		t.Errorf("Want 18. Got %d\n", len(val))
+	}
+	if val[0] != 980.5 {
+		t.Errorf("Want 950.5 Got %f\n", val[0])
+	}
+	if val[17] != 930.5 {
+		t.Errorf("Want 930.5 Got %f\n", val[17])
+	}
+}
+
+func TestGetMetricExceedBoth(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+
+	val, tsFrom, err := m.GetMetric(key, "flops", 1584022800, 1584027900)
+
+	if err != nil {
+		t.Errorf("Got error\n")
+	}
+	if tsFrom != 1584023000 {
+		t.Errorf("Start ts differs: %d\n", tsFrom)
+	}
+	if len(val) != 20 {
+		t.Errorf("Want 20. Got %d\n", len(val))
+	}
+	if val[0] != 100.5 {
+		t.Errorf("Want 950.5 Got %f\n", val[0])
+	}
+	if val[19] != 930.5 {
+		t.Errorf("Want 930.5 Got %f\n", val[17])
+	}
+}
+
+func TestGetMetricOutUpper(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+
+	_, _, err := m.GetMetric(key, "flops", 1584032800, 1584037900)
+
+	if err == nil {
+		t.Errorf("Got no error\n")
+	}
+}
+
+func TestGetMetricOutLower(t *testing.T) {
+	key := "m1220"
+	m := newMemoryStore([]string{"flops", "mem_bw", "mem_capacity"}, 10, 60)
+
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023000+i*60), testMetrics[i])
+	}
+	for i := 0; i < len(testMetrics); i++ {
+		m.AddMetrics(key, int64(1584023600+i*60), testMetricsAlt[i])
+	}
+
+	// printMemStore(m)
+
+	_, _, err := m.GetMetric(key, "flops", 1584002800, 1584007900)
+
+	if err == nil {
+		t.Errorf("Got no error\n")
+	}
+}
--- a/metric-store.go
+++ b/metric-store.go
@@ -0,0 +1,89 @@
+package main
+
+import (
+	"bytes"
+	"encoding/gob"
+	"encoding/json"
+	"fmt"
+	"log"
+	"os"
+	"sync"
+
+	nats "github.com/nats-io/nats.go"
+)
+
+type Config struct {
+	MemoryStore struct {
+		Duration string `json:"duration"`
+	} `json:"memory_store"`
+	FileStore struct {
+		Duration string `json:"duration"`
+	} `json:"file_store"`
+	Root      string   `json:"root"`
+	Frequency int      `json:"frequency"`
+	Metrics   []string `json:"metrics"`
+}
+
+type MetricData struct {
+	Name   string
+	Values []float64
+}
+
+type Metric struct {
+	Name  string
+	Value float64
+}
+
+type message struct {
+	Ts     int64
+	Tags   []string
+	Fields []Metric
+}
+
+var Conf Config
+
+func loadConfiguration(file string) Config {
+	var config Config
+	configFile, err := os.Open(file)
+	defer configFile.Close()
+	if err != nil {
+		fmt.Println(err.Error())
+	}
+	jsonParser := json.NewDecoder(configFile)
+	jsonParser.Decode(&config)
+	return config
+}
+
+func main() {
+
+	Conf = loadConfiguration("config.json")
+
+	// Connect to a server
+	nc, err := nats.Connect(nats.DefaultURL)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer nc.Close()
+
+	var msgBuffer bytes.Buffer
+	dec := gob.NewDecoder(&msgBuffer)
+
+	// Use a WaitGroup to wait for a message to arrive
+	wg := sync.WaitGroup{}
+	wg.Add(1)
+
+	// Subscribe
+	if _, err := nc.Subscribe("updates", func(m *nats.Msg) {
+		log.Println(m.Subject)
+		var p message
+		err = dec.Decode(&p)
+		if err != nil {
+			log.Fatal("decode error 1:", err)
+		}
+	}); err != nil {
+		log.Fatal(err)
+	}
+
+	// Wait for a message to come in
+	wg.Wait()
+}