Merge pull request #20047 from karalabe/counter-to-gauge

core, metrics, p2p: switch some invalid counters to gauges

core/rawdb/freezer.go

@@ -82,7 +82,7 @@ func newFreezer(datadir string, namespace string) (*freezer, error) {
 	var (
 		readMeter  = metrics.NewRegisteredMeter(namespace+"ancient/read", nil)
 		writeMeter = metrics.NewRegisteredMeter(namespace+"ancient/write", nil)
-		sizeCounter = metrics.NewRegisteredCounter(namespace+"ancient/size", nil)
+		sizeGauge  = metrics.NewRegisteredGauge(namespace+"ancient/size", nil)
 	)
 	// Ensure the datadir is not a symbolic link if it exists.
 	if info, err := os.Lstat(datadir); !os.IsNotExist(err) {
@@ -103,7 +103,7 @@ func newFreezer(datadir string, namespace string) (*freezer, error) {
 		instanceLock: lock,
 	}
 	for name, disableSnappy := range freezerNoSnappy {
-		table, err := newTable(datadir, name, readMeter, writeMeter, sizeCounter, disableSnappy)
+		table, err := newTable(datadir, name, readMeter, writeMeter, sizeGauge, disableSnappy)
 		if err != nil {
 			for _, table := range freezer.tables {
 				table.Close()

core/rawdb/freezer_table.go

@@ -97,15 +97,15 @@ type freezerTable struct {
 	headBytes  uint32        // Number of bytes written to the head file
 	readMeter  metrics.Meter // Meter for measuring the effective amount of data read
 	writeMeter metrics.Meter // Meter for measuring the effective amount of data written
-	sizeCounter metrics.Counter // Counter for tracking the combined size of all freezer tables
+	sizeGauge  metrics.Gauge // Gauge for tracking the combined size of all freezer tables
 
 	logger log.Logger   // Logger with database path and table name ambedded
 	lock   sync.RWMutex // Mutex protecting the data file descriptors
 }
 
 // newTable opens a freezer table with default settings - 2G files
-func newTable(path string, name string, readMeter metrics.Meter, writeMeter metrics.Meter, sizeCounter metrics.Counter, disableSnappy bool) (*freezerTable, error) {
+func newTable(path string, name string, readMeter metrics.Meter, writeMeter metrics.Meter, sizeGauge metrics.Gauge, disableSnappy bool) (*freezerTable, error) {
-	return newCustomTable(path, name, readMeter, writeMeter, sizeCounter, 2*1000*1000*1000, disableSnappy)
+	return newCustomTable(path, name, readMeter, writeMeter, sizeGauge, 2*1000*1000*1000, disableSnappy)
 }
 
 // openFreezerFileForAppend opens a freezer table file and seeks to the end
@@ -149,7 +149,7 @@ func truncateFreezerFile(file *os.File, size int64) error {
 // newCustomTable opens a freezer table, creating the data and index files if they are
 // non existent. Both files are truncated to the shortest common length to ensure
 // they don't go out of sync.
-func newCustomTable(path string, name string, readMeter metrics.Meter, writeMeter metrics.Meter, sizeCounter metrics.Counter, maxFilesize uint32, noCompression bool) (*freezerTable, error) {
+func newCustomTable(path string, name string, readMeter metrics.Meter, writeMeter metrics.Meter, sizeGauge metrics.Gauge, maxFilesize uint32, noCompression bool) (*freezerTable, error) {
 	// Ensure the containing directory exists and open the indexEntry file
 	if err := os.MkdirAll(path, 0755); err != nil {
 		return nil, err
@@ -172,7 +172,7 @@ func newCustomTable(path string, name string, readMeter metrics.Meter, writeMete
 		files:         make(map[uint32]*os.File),
 		readMeter:     readMeter,
 		writeMeter:    writeMeter,
-		sizeCounter:   sizeCounter,
+		sizeGauge:     sizeGauge,
 		name:          name,
 		path:          path,
 		logger:        log.New("database", path, "table", name),
@@ -189,7 +189,7 @@ func newCustomTable(path string, name string, readMeter metrics.Meter, writeMete
 		tab.Close()
 		return nil, err
 	}
-	tab.sizeCounter.Inc(int64(size))
+	tab.sizeGauge.Inc(int64(size))
 
 	return tab, nil
 }
@@ -378,7 +378,7 @@ func (t *freezerTable) truncate(items uint64) error {
 	if err != nil {
 		return err
 	}
-	t.sizeCounter.Dec(int64(oldSize - newSize))
+	t.sizeGauge.Dec(int64(oldSize - newSize))
 
 	return nil
 }
@@ -510,7 +510,7 @@ func (t *freezerTable) Append(item uint64, blob []byte) error {
 	t.index.Write(idx.marshallBinary())
 
 	t.writeMeter.Mark(int64(bLen + indexEntrySize))
-	t.sizeCounter.Inc(int64(bLen + indexEntrySize))
+	t.sizeGauge.Inc(int64(bLen + indexEntrySize))
 
 	atomic.AddUint64(&t.items, 1)
 	return nil

core/rawdb/freezer_table_test.go

@@ -56,7 +56,7 @@ func TestFreezerBasics(t *testing.T) {
 	// set cutoff at 50 bytes
 	f, err := newCustomTable(os.TempDir(),
 		fmt.Sprintf("unittest-%d", rand.Uint64()),
-		metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter(), 50, true)
+		metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge(), 50, true)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -99,11 +99,11 @@ func TestFreezerBasicsClosing(t *testing.T) {
 	// set cutoff at 50 bytes
 	var (
 		fname      = fmt.Sprintf("basics-close-%d", rand.Uint64())
-		rm, wm, sc = metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+		rm, wm, sg = metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 		f          *freezerTable
 		err        error
 	)
-	f, err = newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+	f, err = newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -112,7 +112,7 @@ func TestFreezerBasicsClosing(t *testing.T) {
 		data := getChunk(15, x)
 		f.Append(uint64(x), data)
 		f.Close()
-		f, err = newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err = newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -129,7 +129,7 @@ func TestFreezerBasicsClosing(t *testing.T) {
 			t.Fatalf("test %d, got \n%x != \n%x", y, got, exp)
 		}
 		f.Close()
-		f, err = newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err = newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -139,11 +139,11 @@ func TestFreezerBasicsClosing(t *testing.T) {
 // TestFreezerRepairDanglingHead tests that we can recover if index entries are removed
 func TestFreezerRepairDanglingHead(t *testing.T) {
 	t.Parallel()
-	rm, wm, sc := metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 	fname := fmt.Sprintf("dangling_headtest-%d", rand.Uint64())
 
 	{ // Fill table
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -172,7 +172,7 @@ func TestFreezerRepairDanglingHead(t *testing.T) {
 	idxFile.Close()
 	// Now open it again
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -190,11 +190,11 @@ func TestFreezerRepairDanglingHead(t *testing.T) {
 // TestFreezerRepairDanglingHeadLarge tests that we can recover if very many index entries are removed
 func TestFreezerRepairDanglingHeadLarge(t *testing.T) {
 	t.Parallel()
-	rm, wm, sc := metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 	fname := fmt.Sprintf("dangling_headtest-%d", rand.Uint64())
 
 	{ // Fill a table and close it
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -222,7 +222,7 @@ func TestFreezerRepairDanglingHeadLarge(t *testing.T) {
 	idxFile.Close()
 	// Now open it again
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -243,7 +243,7 @@ func TestFreezerRepairDanglingHeadLarge(t *testing.T) {
 	}
 	// And if we open it, we should now be able to read all of them (new values)
 	{
-		f, _ := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, _ := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		for y := 1; y < 255; y++ {
 			exp := getChunk(15, ^y)
 			got, err := f.Retrieve(uint64(y))
@@ -260,11 +260,11 @@ func TestFreezerRepairDanglingHeadLarge(t *testing.T) {
 // TestSnappyDetection tests that we fail to open a snappy database and vice versa
 func TestSnappyDetection(t *testing.T) {
 	t.Parallel()
-	rm, wm, sc := metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 	fname := fmt.Sprintf("snappytest-%d", rand.Uint64())
 	// Open with snappy
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -277,7 +277,7 @@ func TestSnappyDetection(t *testing.T) {
 	}
 	// Open without snappy
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, false)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, false)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -289,7 +289,7 @@ func TestSnappyDetection(t *testing.T) {
 
 	// Open with snappy
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -317,11 +317,11 @@ func assertFileSize(f string, size int64) error {
 // the index is repaired
 func TestFreezerRepairDanglingIndex(t *testing.T) {
 	t.Parallel()
-	rm, wm, sc := metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 	fname := fmt.Sprintf("dangling_indextest-%d", rand.Uint64())
 
 	{ // Fill a table and close it
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -357,7 +357,7 @@ func TestFreezerRepairDanglingIndex(t *testing.T) {
 	// 45, 45, 15
 	// with 3+3+1 items
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -374,11 +374,11 @@ func TestFreezerRepairDanglingIndex(t *testing.T) {
 func TestFreezerTruncate(t *testing.T) {
 
 	t.Parallel()
-	rm, wm, sc := metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 	fname := fmt.Sprintf("truncation-%d", rand.Uint64())
 
 	{ // Fill table
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -395,7 +395,7 @@ func TestFreezerTruncate(t *testing.T) {
 	}
 	// Reopen, truncate
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -417,10 +417,10 @@ func TestFreezerTruncate(t *testing.T) {
 // That will rewind the index, and _should_ truncate the head file
 func TestFreezerRepairFirstFile(t *testing.T) {
 	t.Parallel()
-	rm, wm, sc := metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 	fname := fmt.Sprintf("truncationfirst-%d", rand.Uint64())
 	{ // Fill table
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -448,7 +448,7 @@ func TestFreezerRepairFirstFile(t *testing.T) {
 	}
 	// Reopen
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -473,10 +473,10 @@ func TestFreezerRepairFirstFile(t *testing.T) {
 // - check that we did not keep the rdonly file descriptors
 func TestFreezerReadAndTruncate(t *testing.T) {
 	t.Parallel()
-	rm, wm, sc := metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 	fname := fmt.Sprintf("read_truncate-%d", rand.Uint64())
 	{ // Fill table
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -493,7 +493,7 @@ func TestFreezerReadAndTruncate(t *testing.T) {
 	}
 	// Reopen and read all files
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 50, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 50, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -519,10 +519,10 @@ func TestFreezerReadAndTruncate(t *testing.T) {
 
 func TestOffset(t *testing.T) {
 	t.Parallel()
-	rm, wm, sc := metrics.NewMeter(), metrics.NewMeter(), metrics.NewCounter()
+	rm, wm, sg := metrics.NewMeter(), metrics.NewMeter(), metrics.NewGauge()
 	fname := fmt.Sprintf("offset-%d", rand.Uint64())
 	{ // Fill table
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 40, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 40, true)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -578,7 +578,7 @@ func TestOffset(t *testing.T) {
 	}
 	// Now open again
 	{
-		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sc, 40, true)
+		f, err := newCustomTable(os.TempDir(), fname, rm, wm, sg, 40, true)
 		if err != nil {
 			t.Fatal(err)
 		}

core/tx_pool.go

@@ -101,9 +101,9 @@ var (
 	invalidTxMeter     = metrics.NewRegisteredMeter("txpool/invalid", nil)
 	underpricedTxMeter = metrics.NewRegisteredMeter("txpool/underpriced", nil)
 
-	pendingCounter = metrics.NewRegisteredCounter("txpool/pending", nil)
+	pendingGauge = metrics.NewRegisteredGauge("txpool/pending", nil)
-	queuedCounter  = metrics.NewRegisteredCounter("txpool/queued", nil)
+	queuedGauge  = metrics.NewRegisteredGauge("txpool/queued", nil)
-	localCounter   = metrics.NewRegisteredCounter("txpool/local", nil)
+	localGauge   = metrics.NewRegisteredGauge("txpool/local", nil)
 )
 
 // TxStatus is the current status of a transaction as seen by the pool.
@@ -628,7 +628,7 @@ func (pool *TxPool) add(tx *types.Transaction, local bool) (replaced bool, err e
 		}
 	}
 	if local || pool.locals.contains(from) {
-		localCounter.Inc(1)
+		localGauge.Inc(1)
 	}
 	pool.journalTx(from, tx)
 
@@ -658,7 +658,7 @@ func (pool *TxPool) enqueueTx(hash common.Hash, tx *types.Transaction) (bool, er
 		queuedReplaceMeter.Mark(1)
 	} else {
 		// Nothing was replaced, bump the queued counter
-		queuedCounter.Inc(1)
+		queuedGauge.Inc(1)
 	}
 	if pool.all.Get(hash) == nil {
 		pool.all.Add(tx)
@@ -707,7 +707,7 @@ func (pool *TxPool) promoteTx(addr common.Address, hash common.Hash, tx *types.T
 		pendingReplaceMeter.Mark(1)
 	} else {
 		// Nothing was replaced, bump the pending counter
-		pendingCounter.Inc(1)
+		pendingGauge.Inc(1)
 	}
 	// Failsafe to work around direct pending inserts (tests)
 	if pool.all.Get(hash) == nil {
@@ -841,7 +841,7 @@ func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
 		pool.priced.Removed(1)
 	}
 	if pool.locals.contains(addr) {
-		localCounter.Dec(1)
+		localGauge.Dec(1)
 	}
 	// Remove the transaction from the pending lists and reset the account nonce
 	if pending := pool.pending[addr]; pending != nil {
@@ -858,7 +858,7 @@ func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
 			// Update the account nonce if needed
 			pool.pendingNonces.setIfLower(addr, tx.Nonce())
 			// Reduce the pending counter
-			pendingCounter.Dec(int64(1 + len(invalids)))
+			pendingGauge.Dec(int64(1 + len(invalids)))
 			return
 		}
 	}
@@ -866,7 +866,7 @@ func (pool *TxPool) removeTx(hash common.Hash, outofbound bool) {
 	if future := pool.queue[addr]; future != nil {
 		if removed, _ := future.Remove(tx); removed {
 			// Reduce the queued counter
-			queuedCounter.Dec(1)
+			queuedGauge.Dec(1)
 		}
 		if future.Empty() {
 			delete(pool.queue, addr)
@@ -1164,7 +1164,7 @@ func (pool *TxPool) promoteExecutables(accounts []common.Address) []*types.Trans
 				promoted = append(promoted, tx)
 			}
 		}
-		queuedCounter.Dec(int64(len(readies)))
+		queuedGauge.Dec(int64(len(readies)))
 
 		// Drop all transactions over the allowed limit
 		var caps types.Transactions
@@ -1179,9 +1179,9 @@ func (pool *TxPool) promoteExecutables(accounts []common.Address) []*types.Trans
 		}
 		// Mark all the items dropped as removed
 		pool.priced.Removed(len(forwards) + len(drops) + len(caps))
-		queuedCounter.Dec(int64(len(forwards) + len(drops) + len(caps)))
+		queuedGauge.Dec(int64(len(forwards) + len(drops) + len(caps)))
 		if pool.locals.contains(addr) {
-			localCounter.Dec(int64(len(forwards) + len(drops) + len(caps)))
+			localGauge.Dec(int64(len(forwards) + len(drops) + len(caps)))
 		}
 		// Delete the entire queue entry if it became empty.
 		if list.Empty() {
@@ -1240,9 +1240,9 @@ func (pool *TxPool) truncatePending() {
 						log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
 					}
 					pool.priced.Removed(len(caps))
-					pendingCounter.Dec(int64(len(caps)))
+					pendingGauge.Dec(int64(len(caps)))
 					if pool.locals.contains(offenders[i]) {
-						localCounter.Dec(int64(len(caps)))
+						localGauge.Dec(int64(len(caps)))
 					}
 					pending--
 				}
@@ -1267,9 +1267,9 @@ func (pool *TxPool) truncatePending() {
 					log.Trace("Removed fairness-exceeding pending transaction", "hash", hash)
 				}
 				pool.priced.Removed(len(caps))
-				pendingCounter.Dec(int64(len(caps)))
+				pendingGauge.Dec(int64(len(caps)))
 				if pool.locals.contains(addr) {
-					localCounter.Dec(int64(len(caps)))
+					localGauge.Dec(int64(len(caps)))
 				}
 				pending--
 			}
@@ -1353,9 +1353,9 @@ func (pool *TxPool) demoteUnexecutables() {
 			log.Trace("Demoting pending transaction", "hash", hash)
 			pool.enqueueTx(hash, tx)
 		}
-		pendingCounter.Dec(int64(len(olds) + len(drops) + len(invalids)))
+		pendingGauge.Dec(int64(len(olds) + len(drops) + len(invalids)))
 		if pool.locals.contains(addr) {
-			localCounter.Dec(int64(len(olds) + len(drops) + len(invalids)))
+			localGauge.Dec(int64(len(olds) + len(drops) + len(invalids)))
 		}
 		// If there's a gap in front, alert (should never happen) and postpone all transactions
 		if list.Len() > 0 && list.txs.Get(nonce) == nil {
@@ -1365,7 +1365,7 @@ func (pool *TxPool) demoteUnexecutables() {
 				log.Error("Demoting invalidated transaction", "hash", hash)
 				pool.enqueueTx(hash, tx)
 			}
-			pendingCounter.Dec(int64(len(gapped)))
+			pendingGauge.Dec(int64(len(gapped)))
 		}
 		// Delete the entire queue entry if it became empty.
 		if list.Empty() {

metrics/gauge.go

@@ -6,6 +6,8 @@ import "sync/atomic"
 type Gauge interface {
 	Snapshot() Gauge
 	Update(int64)
+	Dec(int64)
+	Inc(int64)
 	Value() int64
 }
 
@@ -65,6 +67,16 @@ func (GaugeSnapshot) Update(int64) {
 	panic("Update called on a GaugeSnapshot")
 }
 
+// Dec panics.
+func (GaugeSnapshot) Dec(int64) {
+	panic("Dec called on a GaugeSnapshot")
+}
+
+// Inc panics.
+func (GaugeSnapshot) Inc(int64) {
+	panic("Inc called on a GaugeSnapshot")
+}
+
 // Value returns the value at the time the snapshot was taken.
 func (g GaugeSnapshot) Value() int64 { return int64(g) }
 
@@ -77,6 +89,12 @@ func (NilGauge) Snapshot() Gauge { return NilGauge{} }
 // Update is a no-op.
 func (NilGauge) Update(v int64) {}
 
+// Dec is a no-op.
+func (NilGauge) Dec(i int64) {}
+
+// Inc is a no-op.
+func (NilGauge) Inc(i int64) {}
+
 // Value is a no-op.
 func (NilGauge) Value() int64 { return 0 }
 
@@ -101,6 +119,16 @@ func (g *StandardGauge) Value() int64 {
 	return atomic.LoadInt64(&g.value)
 }
 
+// Dec decrements the gauge's current value by the given amount.
+func (g *StandardGauge) Dec(i int64) {
+	atomic.AddInt64(&g.value, -i)
+}
+
+// Inc increments the gauge's current value by the given amount.
+func (g *StandardGauge) Inc(i int64) {
+	atomic.AddInt64(&g.value, i)
+}
+
 // FunctionalGauge returns value from given function
 type FunctionalGauge struct {
 	value func() int64
@@ -118,3 +146,13 @@ func (g FunctionalGauge) Snapshot() Gauge { return GaugeSnapshot(g.Value()) }
 func (FunctionalGauge) Update(int64) {
 	panic("Update called on a FunctionalGauge")
 }
+
+// Dec panics.
+func (FunctionalGauge) Dec(int64) {
+	panic("Dec called on a FunctionalGauge")
+}
+
+// Inc panics.
+func (FunctionalGauge) Inc(int64) {
+	panic("Inc called on a FunctionalGauge")
+}

p2p/metrics.go

@@ -45,7 +45,7 @@ var (
 	ingressTrafficMeter = metrics.NewRegisteredMeter(MetricsInboundTraffic, nil)   // Meter metering the cumulative ingress traffic
 	egressConnectMeter  = metrics.NewRegisteredMeter(MetricsOutboundConnects, nil) // Meter counting the egress connections
 	egressTrafficMeter  = metrics.NewRegisteredMeter(MetricsOutboundTraffic, nil)  // Meter metering the cumulative egress traffic
-	activePeerCounter   = metrics.NewRegisteredCounter("p2p/peers", nil)           // Gauge tracking the current peer count
+	activePeerGauge     = metrics.NewRegisteredGauge("p2p/peers", nil)             // Gauge tracking the current peer count
 
 	PeerIngressRegistry = metrics.NewPrefixedChildRegistry(metrics.EphemeralRegistry, MetricsInboundTraffic+"/")  // Registry containing the peer ingress
 	PeerEgressRegistry  = metrics.NewPrefixedChildRegistry(metrics.EphemeralRegistry, MetricsOutboundTraffic+"/") // Registry containing the peer egress
@@ -124,7 +124,7 @@ func newMeteredConn(conn net.Conn, ingress bool, ip net.IP) net.Conn {
 	} else {
 		egressConnectMeter.Mark(1)
 	}
-	activePeerCounter.Inc(1)
+	activePeerGauge.Inc(1)
 
 	return &meteredConn{
 		Conn:      conn,
@@ -200,7 +200,7 @@ func (c *meteredConn) Close() error {
 			IP:      c.ip,
 			Elapsed: time.Since(c.connected),
 		})
-		activePeerCounter.Dec(1)
+		activePeerGauge.Dec(1)
 		return err
 	}
 	id := c.id
@@ -212,7 +212,7 @@ func (c *meteredConn) Close() error {
 			IP:   c.ip,
 			ID:   id,
 		})
-		activePeerCounter.Dec(1)
+		activePeerGauge.Dec(1)
 		return err
 	}
 	ingress, egress := uint64(c.ingressMeter.Count()), uint64(c.egressMeter.Count())
@@ -233,6 +233,6 @@ func (c *meteredConn) Close() error {
 		Ingress: ingress,
 		Egress:  egress,
 	})
-	activePeerCounter.Dec(1)
+	activePeerGauge.Dec(1)
 	return err
 }