add metrics for dns

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util/dns/cache.go

@@ -6,6 +6,9 @@ import (
 	"net"
 	"sync"
 	"time"
+
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/semconv"
 )
 
 // DialFunc is a [net.Resolver.Dial] function.
@@ -19,6 +22,11 @@ func NewNetResolver(opts ...Option) *net.Resolver {
 		o(&options)
 	}
 
+	if options.Meter == nil {
+		options.Meter = meter.DefaultMeter
+		opts = append(opts, Meter(options.Meter))
+	}
+
 	return &net.Resolver{
 		PreferGo:     true,
 		StrictErrors: options.Resolver.StrictErrors,
@@ -56,6 +64,7 @@ type Options struct {
 	PreferIPV4      bool
 	PreferIPV6      bool
 	Timeout         time.Duration
+	Meter           meter.Meter
 }
 
 // MaxCacheEntries sets the maximum number of entries to cache.
@@ -87,6 +96,13 @@ func NegativeCache(b bool) Option {
 	}
 }
 
+// Meter sets meter.Meter
+func Meter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
 // Timeout sets upstream *net.Resolver timeout
 func Timeout(td time.Duration) Option {
 	return func(o *Options) {
@@ -156,7 +172,6 @@ func (c *cache) put(req string, res string) {
 	}
 
 	c.Lock()
-	defer c.Unlock()
 	if c.entries == nil {
 		c.entries = make(map[string]cacheEntry)
 	}
@@ -165,6 +180,8 @@ func (c *cache) put(req string, res string) {
 	var tested, evicted int
 	for k, e := range c.entries {
 		if time.Until(e.deadline) <= 0 {
+			c.opts.Meter.Counter(semconv.CacheItemsTotal, "type", "dns").Dec()
+			c.opts.Meter.Counter(semconv.CacheRequestTotal, "type", "dns", "method", "evict").Inc()
 			// delete expired entry
 			delete(c.entries, k)
 			evicted++
@@ -175,6 +192,8 @@ func (c *cache) put(req string, res string) {
 			continue
 		}
 		if evicted == 0 && c.opts.MaxCacheEntries > 0 && len(c.entries) >= c.opts.MaxCacheEntries {
+			c.opts.Meter.Counter(semconv.CacheItemsTotal, "type", "dns").Dec()
+			c.opts.Meter.Counter(semconv.CacheRequestTotal, "type", "dns", "method", "evict").Inc()
 			// delete at least one entry
 			delete(c.entries, k)
 		}
@@ -186,6 +205,9 @@ func (c *cache) put(req string, res string) {
 		deadline: time.Now().Add(ttl),
 		value:    res[2:],
 	}
+
+	c.opts.Meter.Counter(semconv.CacheItemsTotal, "type", "dns").Inc()
+	c.Unlock()
 }
 
 func (c *cache) get(req string) (res string) {
@@ -210,6 +232,7 @@ func (c *cache) get(req string) (res string) {
 		// prepend correct ID
 		return req[:2] + entry.value
 	}
+
 	return ""
 }
 
@@ -310,10 +333,19 @@ func getUint32(s string) int {
 
 func cachingRoundTrip(cache *cache, network, address string) roundTripper {
 	return func(ctx context.Context, req string) (res string, err error) {
+		cache.opts.Meter.Counter(semconv.CacheRequestInflight, "type", "dns").Inc()
+		defer cache.opts.Meter.Counter(semconv.CacheRequestInflight, "type", "dns").Dec()
 		// check cache
 		if res := cache.get(req); res != "" {
+			cache.opts.Meter.Counter(semconv.CacheRequestTotal, "type", "dns", "method", "get", "status", "hit").Inc()
 			return res, nil
 		}
+		cache.opts.Meter.Counter(semconv.CacheRequestTotal, "type", "dns", "method", "get", "status", "miss").Inc()
+		ts := time.Now()
+		defer func() {
+			cache.opts.Meter.Summary(semconv.CacheRequestLatencyMicroseconds, "type", "dns", "method", "get").UpdateDuration(ts)
+			cache.opts.Meter.Histogram(semconv.CacheRequestDurationSeconds, "type", "dns", "method", "get").UpdateDuration(ts)
+		}()
 
 		switch {
 		case cache.opts.PreferIPV4 && cache.opts.PreferIPV6:
@@ -340,6 +372,7 @@ func cachingRoundTrip(cache *cache, network, address string) roundTripper {
 			var d net.Dialer
 			conn, err = d.DialContext(ctx, network, address)
 		}
+
 		if err != nil {
 			return "", err
 		}

util/dns/cache_test.go

@@ -12,5 +12,11 @@ func TestCache(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	t.Logf("addrs %v", addrs)
+
+	addrs, err = net.LookupHost("unistack.org")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_ = addrs
 }

util/dns/conn.go

@@ -11,15 +11,13 @@ import (
 )
 
 type dnsConn struct {
-	sync.Mutex
-
-	ibuf bytes.Buffer
-	obuf bytes.Buffer
-
+	deadline  time.Time
 	ctx       context.Context
 	cancel    context.CancelFunc
-	deadline  time.Time
 	roundTrip roundTripper
+	ibuf      bytes.Buffer
+	obuf      bytes.Buffer
+	sync.Mutex
 }
 
 type roundTripper func(ctx context.Context, req string) (res string, err error)
@@ -78,8 +76,8 @@ func (c *dnsConn) SetDeadline(t time.Time) error {
 
 func (c *dnsConn) SetReadDeadline(t time.Time) error {
 	c.Lock()
-	defer c.Unlock()
 	c.deadline = t
+	c.Unlock()
 	return nil
 }