From ee47364474bd7d1ab376a213b67fd1ae07115d26 Mon Sep 17 00:00:00 2001
From: Lou Knauer <lou.knauer@gmx.de>
Date: Fri, 20 Aug 2021 09:39:05 +0200
Subject: [PATCH] Implement lineprotocol parser

---
 lineprotocol/lineprotocol.go      | 73 +++++++++++++++++++++++++++++++
 lineprotocol/lineprotocol_test.go | 64 +++++++++++++++++++++++++++
 2 files changed, 137 insertions(+)
 create mode 100644 lineprotocol/lineprotocol.go
 create mode 100644 lineprotocol/lineprotocol_test.go

diff --git a/lineprotocol/lineprotocol.go b/lineprotocol/lineprotocol.go
new file mode 100644
index 0000000..6987ffb
--- /dev/null
+++ b/lineprotocol/lineprotocol.go
@@ -0,0 +1,73 @@
+package lineprotocol
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type Metric struct {
+	Name  string
+	Value float64
+}
+
+// measurement: node or cpu
+// tags:        host, cluster, cpu (cpu only if measurement is cpu)
+// fields:      metrics...
+// t:           timestamp (accuracy: seconds)
+type Line struct {
+	measurement string
+	tags        map[string]string
+	fields      []Metric
+	t           time.Time
+}
+
+// Parse a single line as string.
+//
+// There is performance to be gained by implementing a parser
+// that directly reads from a bufio.Scanner.
+func Parse(rawline string) (*Line, error) {
+	line := &Line{}
+	parts := strings.Fields(rawline)
+	if len(parts) != 3 {
+		return nil, errors.New("line format error")
+	}
+
+	tagsAndMeasurement := strings.Split(parts[0], ",")
+	line.measurement = tagsAndMeasurement[0]
+	line.tags = map[string]string{}
+	for i := 1; i < len(tagsAndMeasurement); i++ {
+		pair := strings.Split(tagsAndMeasurement[i], "=")
+		if len(pair) != 2 {
+			return nil, errors.New("line format error")
+		}
+		line.tags[pair[0]] = pair[1]
+	}
+
+	rawfields := strings.Split(parts[1], ",")
+	line.fields = []Metric{}
+	for i := 0; i < len(rawfields); i++ {
+		pair := strings.Split(rawfields[i], "=")
+		if len(pair) != 2 {
+			return nil, errors.New("line format error")
+		}
+		field, err := strconv.ParseFloat(pair[1], 64)
+		if err != nil {
+			return nil, err
+		}
+
+		line.fields = append(line.fields, Metric{
+			Name:  pair[0],
+			Value: field,
+		})
+	}
+
+	unixTimestamp, err := strconv.ParseInt(parts[2], 10, 64)
+	if err != nil {
+		return nil, err
+	}
+
+	line.t = time.Unix(unixTimestamp, 0)
+	return line, nil
+}
diff --git a/lineprotocol/lineprotocol_test.go b/lineprotocol/lineprotocol_test.go
new file mode 100644
index 0000000..1f17cb6
--- /dev/null
+++ b/lineprotocol/lineprotocol_test.go
@@ -0,0 +1,64 @@
+package lineprotocol
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestParse(t *testing.T) {
+	raw := `node,host=lousxps,cluster=test mem_used=4692.252,proc_total=1083,load_five=0.91,cpu_user=1.424336e+06,cpu_guest_nice=0,cpu_guest=0,mem_available=9829.848,mem_slab=514.796,mem_free=4537.956,proc_run=2,cpu_idle=2.1589764e+07,swap_total=0,mem_cached=6368.5,swap_free=0,load_fifteen=0.93,cpu_nice=196,cpu_softirq=41456,mem_buffers=489.992,mem_total=16088.7,load_one=0.84,cpu_system=517223,cpu_iowait=8994,cpu_steal=0,cpu_irq=113265,mem_sreclaimable=362.452 1629356936`
+	expectedMeasurement := `node`
+	expectedTags := map[string]string{
+		"host":    "lousxps",
+		"cluster": "test",
+	}
+	expectedFields := []Metric{
+		{"mem_used", 4692.252},
+		{"proc_total", 1083},
+		{"load_five", 0.91},
+		{"cpu_user", 1.424336e+06},
+		{"cpu_guest_nice", 0},
+		{"cpu_guest", 0},
+		{"mem_available", 9829.848},
+		{"mem_slab", 514.796},
+		{"mem_free", 4537.956},
+		{"proc_run", 2},
+		{"cpu_idle", 2.1589764e+07},
+		{"swap_total", 0},
+		{"mem_cached", 6368.5},
+		{"swap_free", 0},
+		{"load_fifteen", 0.93},
+		{"cpu_nice", 196},
+		{"cpu_softirq", 41456},
+		{"mem_buffers", 489.992},
+		{"mem_total", 16088.7},
+		{"load_one", 0.84},
+		{"cpu_system", 517223},
+		{"cpu_iowait", 8994},
+		{"cpu_steal", 0},
+		{"cpu_irq", 113265},
+		{"mem_sreclaimable", 362.452},
+	}
+	expectedTimestamp := 1629356936
+
+	line, err := Parse(raw)
+	if err != nil {
+		t.Error(err)
+	}
+
+	if line.measurement != expectedMeasurement {
+		t.Error("measurement not as expected")
+	}
+
+	if line.t.Unix() != int64(expectedTimestamp) {
+		t.Error("timestamp not as expected")
+	}
+
+	if !reflect.DeepEqual(line.tags, expectedTags) {
+		t.Error("tags not as expected")
+	}
+
+	if !reflect.DeepEqual(line.fields, expectedFields) {
+		t.Error("fields not as expected")
+	}
+}