Fetching Statistics from memcached server

Author: Konstantin Nikitin

memcache/memcache.go

@@ -110,6 +110,12 @@ var (
 	resultTouched   = []byte("TOUCHED\r\n")
 
 	resultClientErrorPrefix = []byte("CLIENT_ERROR ")
+
+	statsGetHits      = []byte("STAT get_hits ")
+	statsGetMisses    = []byte("STAT get_misses ")
+	statsBytesWritten = []byte("STAT bytes_written ")
+	statsItems        = []byte("STAT curr_items ")
+	statsBytes        = []byte("STAT bytes ")
 )
 
 // New returns a memcache client using the provided server(s)
@@ -171,6 +177,24 @@ type conn struct {
 	c    *Client
 }
 
+// Statistics is a record of memcached usage stats.
+type Statistics struct {
+	// Counter of cache hits.
+	Hits uint64
+
+	// Counter of cache misses.
+	Misses uint64
+
+	// Counter of bytes transferred for gets.
+	ByteHits uint64
+
+	// Items currently in the cache.
+	Items uint64
+
+	// Size of all items currently in the cache.
+	Bytes uint64
+}
+
 // release returns this connection back to the client's free pool
 func (cn *conn) release() {
 	cn.c.putFreeConn(cn.addr, cn)
@@ -667,3 +691,63 @@ func (c *Client) incrDecr(verb, key string, delta uint64) (uint64, error) {
 	})
 	return val, err
 }
+
+func parseStatsLine(s []byte, expectedPrefix []byte) (uint64, error) {
+          if !bytes.HasPrefix(s, expectedPrefix) {
+                    return 0, errors.New("line does not start with exceptedPrefix")
+          }
+          return strconv.ParseUint(
+              string(s[len(expectedPrefix):len(s)-2]), 10, 64)
+}
+
+// parseStatsResponse reads a GET response from r and calls cb for each
+// read and allocated Item
+func parseStatsResponse(r *bufio.Reader, stats *Statistics) error {
+	for {
+		line, err := r.ReadSlice('\n')
+		if err != nil {
+			return err
+		}
+		if bytes.Equal(line, resultEnd) {
+			return nil
+		}
+		if hits, err := parseStatsLine(line, statsGetHits); err == nil {
+			stats.Hits = hits
+			continue
+		}
+		if misses, err := parseStatsLine(line, statsGetMisses); err == nil {
+			stats.Misses = misses
+			continue
+		}
+		if bytesWritten, err := parseStatsLine(line, statsBytesWritten); err == nil {
+			stats.ByteHits = bytesWritten
+			continue
+		}
+		if items, err := parseStatsLine(line, statsItems); err == nil {
+			stats.Items = items
+			continue
+		}
+		if bytes_total, err := parseStatsLine(line, statsBytes); err == nil {
+			stats.Bytes = bytes_total
+			continue
+		}
+	}
+}
+
+
+func (c *Client) Stats(addr net.Addr) (*Statistics, error) {
+          stats := new(Statistics)
+          err := c.withAddrRw(addr, func(rw *bufio.ReadWriter) error {
+		if _, err := fmt.Fprintf(rw, "stats\r\n"); err != nil {
+			return err
+		}
+		if err := rw.Flush(); err != nil {
+			return err
+		}
+		if err := parseStatsResponse(rw.Reader, stats); err != nil {
+			return err
+		}
+		return nil
+	})
+	return stats, err
+}