1 files changed, 121 insertions, 0 deletions
diff --git a/src/go/plugin/go.d/modules/memcached/collect.go b/src/go/plugin/go.d/modules/memcached/collect.go
new file mode 100644
index 000000000..9ead8f47b
--- /dev/null
+++ b/src/go/plugin/go.d/modules/memcached/collect.go
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package memcached
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"strconv"
+	"strings"
+)
+
+// https://github.com/memcached/memcached/blob/b1aefcdf8a265f8a5126e8aa107a50988fa1ec35/doc/protocol.txt#L1267
+var statsMetrics = map[string]bool{
+	"limit_maxbytes":       true,
+	"bytes":                true,
+	"bytes_read":           true,
+	"bytes_written":        true,
+	"cas_badval":           true,
+	"cas_hits":             true,
+	"cas_misses":           true,
+	"cmd_get":              true,
+	"cmd_set":              true,
+	"cmd_touch":            true,
+	"curr_connections":     true,
+	"curr_items":           true,
+	"decr_hits":            true,
+	"decr_misses":          true,
+	"delete_hits":          true,
+	"delete_misses":        true,
+	"evictions":            true,
+	"get_hits":             true,
+	"get_misses":           true,
+	"incr_hits":            true,
+	"incr_misses":          true,
+	"reclaimed":            true,
+	"rejected_connections": true,
+	"total_connections":    true,
+	"total_items":          true,
+	"touch_hits":           true,
+	"touch_misses":         true,
+}
+
+func (m *Memcached) collect() (map[string]int64, error) {
+	if m.conn == nil {
+		conn, err := m.establishConn()
+		if err != nil {
+			return nil, err
+		}
+		m.conn = conn
+	}
+
+	stats, err := m.conn.queryStats()
+	if err != nil {
+		m.conn.disconnect()
+		m.conn = nil
+		return nil, err
+	}
+
+	mx := make(map[string]int64)
+
+	if err := m.collectStats(mx, stats); err != nil {
+		return nil, err
+	}
+
+	return mx, nil
+}
+
+func (m *Memcached) collectStats(mx map[string]int64, stats []byte) error {
+	if len(stats) == 0 {
+		return errors.New("empty stats response")
+	}
+
+	var n int
+	sc := bufio.NewScanner(bytes.NewReader(stats))
+
+	for sc.Scan() {
+		line := strings.TrimSpace(sc.Text())
+
+		switch {
+		case strings.HasPrefix(line, "STAT"):
+			key, value := getStatKeyValue(line)
+			if !statsMetrics[key] {
+				continue
+			}
+			if v, err := strconv.ParseInt(value, 10, 64); err == nil {
+				mx[key] = v
+				n++
+			}
+		case strings.HasPrefix(line, "ERROR"):
+			return errors.New("received ERROR response")
+		}
+	}
+
+	if n == 0 {
+		return errors.New("unexpected memcached response")
+	}
+
+	mx["avail"] = mx["limit_maxbytes"] - mx["bytes"]
+
+	return nil
+}
+
+func (m *Memcached) establishConn() (memcachedConn, error) {
+	conn := m.newMemcachedConn(m.Config)
+
+	if err := conn.connect(); err != nil {
+		return nil, err
+	}
+
+	return conn, nil
+}
+
+func getStatKeyValue(line string) (string, string) {
+	line = strings.TrimPrefix(line, "STAT ")
+	i := strings.IndexByte(line, ' ')
+	if i < 0 {
+		return "", ""
+	}
+	return line[:i], line[i+1:]
+}