storage: Replace usage of sync/atomic with uber-go/atomic

Signed-off-by: Javier Palomo <javier.palomo.almena@gmail.com>

storage/remote/ewma.go

@@ -15,15 +15,14 @@ package remote
 
 import (
 	"sync"
-	"sync/atomic"
 	"time"
+
+	"go.uber.org/atomic"
 )
 
 // ewmaRate tracks an exponentially weighted moving average of a per-second rate.
 type ewmaRate struct {
-	// Keep all 64bit atomically accessed variables at the top of this struct.
+	newEvents atomic.Int64
-	// See https://golang.org/pkg/sync/atomic/#pkg-note-BUG for more info.
-	newEvents int64
 
 	alpha    float64
 	interval time.Duration
@@ -50,7 +49,7 @@ func (r *ewmaRate) rate() float64 {
 
 // tick assumes to be called every r.interval.
 func (r *ewmaRate) tick() {
-	newEvents := atomic.SwapInt64(&r.newEvents, 0)
+	newEvents := r.newEvents.Swap(0)
 	instantRate := float64(newEvents) / r.interval.Seconds()
 
 	r.mutex.Lock()
@@ -66,5 +65,5 @@ func (r *ewmaRate) tick() {
 
 // inc counts one event.
 func (r *ewmaRate) incr(incr int64) {
-	atomic.AddInt64(&r.newEvents, incr)
+	r.newEvents.Add(incr)
 }

storage/remote/intern.go

@@ -20,10 +20,10 @@ package remote
 
 import (
 	"sync"
-	"sync/atomic"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
+	"go.uber.org/atomic"
 )
 
 var interner = newPool()
@@ -40,13 +40,17 @@ type pool struct {
 }
 
 type entry struct {
-	// Keep all 64bit atomically accessed variables at the top of this struct.
+	refs atomic.Int64
-	// See https://golang.org/pkg/sync/atomic/#pkg-note-BUG for more info.
-	refs int64
 
 	s string
 }
 
+func newEntry(s string) *entry {
+	entry := &entry{s: s}
+	entry.refs.Store(1)
+	return entry
+}
+
 func newPool() *pool {
 	return &pool{
 		pool: map[string]*entry{},
@@ -62,20 +66,17 @@ func (p *pool) intern(s string) string {
 	interned, ok := p.pool[s]
 	p.mtx.RUnlock()
 	if ok {
-		atomic.AddInt64(&interned.refs, 1)
+		interned.refs.Inc()
 		return interned.s
 	}
 	p.mtx.Lock()
 	defer p.mtx.Unlock()
 	if interned, ok := p.pool[s]; ok {
-		atomic.AddInt64(&interned.refs, 1)
+		interned.refs.Inc()
 		return interned.s
 	}
 
-	p.pool[s] = &entry{
+	p.pool[s] = newEntry(s)
-		s:    s,
-		refs: 1,
-	}
 	return s
 }
 
@@ -89,14 +90,14 @@ func (p *pool) release(s string) {
 		return
 	}
 
-	refs := atomic.AddInt64(&interned.refs, -1)
+	refs := interned.refs.Dec()
 	if refs > 0 {
 		return
 	}
 
 	p.mtx.Lock()
 	defer p.mtx.Unlock()
-	if atomic.LoadInt64(&interned.refs) != 0 {
+	if interned.refs.Load() != 0 {
 		return
 	}
 	delete(p.pool, s)

storage/remote/intern_test.go

@@ -20,7 +20,6 @@ package remote
 
 import (
 	"fmt"
-	"sync/atomic"
 	"testing"
 	"time"
 
@@ -33,7 +32,7 @@ func TestIntern(t *testing.T) {
 	interned, ok := interner.pool[testString]
 
 	testutil.Equals(t, true, ok)
-	testutil.Assert(t, interned.refs == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
+	testutil.Assert(t, interned.refs.Load() == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
 }
 
 func TestIntern_MultiRef(t *testing.T) {
@@ -43,13 +42,13 @@ func TestIntern_MultiRef(t *testing.T) {
 	interned, ok := interner.pool[testString]
 
 	testutil.Equals(t, true, ok)
-	testutil.Assert(t, interned.refs == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
+	testutil.Assert(t, interned.refs.Load() == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
 
 	interner.intern(testString)
 	interned, ok = interner.pool[testString]
 
 	testutil.Equals(t, true, ok)
-	testutil.Assert(t, interned.refs == 2, fmt.Sprintf("expected refs to be 2 but it was %d", interned.refs))
+	testutil.Assert(t, interned.refs.Load() == 2, fmt.Sprintf("expected refs to be 2 but it was %d", interned.refs))
 }
 
 func TestIntern_DeleteRef(t *testing.T) {
@@ -59,7 +58,7 @@ func TestIntern_DeleteRef(t *testing.T) {
 	interned, ok := interner.pool[testString]
 
 	testutil.Equals(t, true, ok)
-	testutil.Assert(t, interned.refs == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
+	testutil.Assert(t, interned.refs.Load() == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
 
 	interner.release(testString)
 	_, ok = interner.pool[testString]
@@ -72,7 +71,7 @@ func TestIntern_MultiRef_Concurrent(t *testing.T) {
 	interner.intern(testString)
 	interned, ok := interner.pool[testString]
 	testutil.Equals(t, true, ok)
-	testutil.Assert(t, interned.refs == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
+	testutil.Assert(t, interned.refs.Load() == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
 
 	go interner.release(testString)
 
@@ -84,5 +83,5 @@ func TestIntern_MultiRef_Concurrent(t *testing.T) {
 	interned, ok = interner.pool[testString]
 	interner.mtx.RUnlock()
 	testutil.Equals(t, true, ok)
-	testutil.Assert(t, atomic.LoadInt64(&interned.refs) == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
+	testutil.Assert(t, interned.refs.Load() == 1, fmt.Sprintf("expected refs to be 1 but it was %d", interned.refs))
 }

storage/remote/queue_manager.go

@@ -18,7 +18,6 @@ import (
 	"math"
 	"strconv"
 	"sync"
-	"sync/atomic"
 	"time"
 
 	"github.com/go-kit/kit/log"
@@ -35,6 +34,8 @@ import (
 	"github.com/prometheus/prometheus/prompb"
 	"github.com/prometheus/prometheus/tsdb/record"
 	"github.com/prometheus/prometheus/tsdb/wal"
+
+	"go.uber.org/atomic"
 )
 
 const (
@@ -235,8 +236,7 @@ type WriteClient interface {
 // indicated by the provided WriteClient. Implements writeTo interface
 // used by WAL Watcher.
 type QueueManager struct {
-	// https://golang.org/pkg/sync/atomic/#pkg-note-BUG
+	lastSendTimestamp atomic.Int64
-	lastSendTimestamp int64
 
 	logger         log.Logger
 	flushDeadline  time.Duration
@@ -537,7 +537,7 @@ func (t *QueueManager) shouldReshard(desiredShards int) bool {
 	// We shouldn't reshard if Prometheus hasn't been able to send to the
 	// remote endpoint successfully within some period of time.
 	minSendTimestamp := time.Now().Add(-2 * time.Duration(t.cfg.BatchSendDeadline)).Unix()
-	lsts := atomic.LoadInt64(&t.lastSendTimestamp)
+	lsts := t.lastSendTimestamp.Load()
 	if lsts < minSendTimestamp {
 		level.Warn(t.logger).Log("msg", "Skipping resharding, last successful send was beyond threshold", "lastSendTimestamp", lsts, "minSendTimestamp", minSendTimestamp)
 		return false
@@ -663,7 +663,7 @@ type shards struct {
 	// Emulate a wait group with a channel and an atomic int, as you
 	// cannot select on a wait group.
 	done    chan struct{}
-	running int32
+	running atomic.Int32
 
 	// Soft shutdown context will prevent new enqueues and deadlocks.
 	softShutdown chan struct{}
@@ -671,7 +671,7 @@ type shards struct {
 	// Hard shutdown context is used to terminate outgoing HTTP connections
 	// after giving them a chance to terminate.
 	hardShutdown          context.CancelFunc
-	droppedOnHardShutdown uint32
+	droppedOnHardShutdown atomic.Uint32
 }
 
 // start the shards; must be called before any call to enqueue.
@@ -692,9 +692,9 @@ func (s *shards) start(n int) {
 	var hardShutdownCtx context.Context
 	hardShutdownCtx, s.hardShutdown = context.WithCancel(context.Background())
 	s.softShutdown = make(chan struct{})
-	s.running = int32(n)
+	s.running.Store(int32(n))
 	s.done = make(chan struct{})
-	atomic.StoreUint32(&s.droppedOnHardShutdown, 0)
+	s.droppedOnHardShutdown.Store(0)
 	for i := 0; i < n; i++ {
 		go s.runShard(hardShutdownCtx, i, newQueues[i])
 	}
@@ -727,7 +727,7 @@ func (s *shards) stop() {
 	// Force an unclean shutdown.
 	s.hardShutdown()
 	<-s.done
-	if dropped := atomic.LoadUint32(&s.droppedOnHardShutdown); dropped > 0 {
+	if dropped := s.droppedOnHardShutdown.Load(); dropped > 0 {
 		level.Error(s.qm.logger).Log("msg", "Failed to flush all samples on shutdown", "count", dropped)
 	}
 }
@@ -756,7 +756,7 @@ func (s *shards) enqueue(ref uint64, sample sample) bool {
 
 func (s *shards) runShard(ctx context.Context, shardID int, queue chan sample) {
 	defer func() {
-		if atomic.AddInt32(&s.running, -1) == 0 {
+		if s.running.Dec() == 0 {
 			close(s.done)
 		}
 	}()
@@ -792,7 +792,7 @@ func (s *shards) runShard(ctx context.Context, shardID int, queue chan sample) {
 			droppedSamples := nPending + len(queue)
 			s.qm.metrics.pendingSamples.Sub(float64(droppedSamples))
 			s.qm.metrics.failedSamplesTotal.Add(float64(droppedSamples))
-			atomic.AddUint32(&s.droppedOnHardShutdown, uint32(droppedSamples))
+			s.droppedOnHardShutdown.Add(uint32(droppedSamples))
 			return
 
 		case sample, ok := <-queue:
@@ -847,7 +847,7 @@ func (s *shards) sendSamples(ctx context.Context, samples []prompb.TimeSeries, b
 	// should be maintained irrespective of success or failure.
 	s.qm.samplesOut.incr(int64(len(samples)))
 	s.qm.samplesOutDuration.incr(int64(time.Since(begin)))
-	atomic.StoreInt64(&s.qm.lastSendTimestamp, time.Now().Unix())
+	s.qm.lastSendTimestamp.Store(time.Now().Unix())
 }
 
 // sendSamples to the remote storage with backoff for recoverable errors.

storage/remote/queue_manager_test.go

@@ -24,7 +24,6 @@ import (
 	"strconv"
 	"strings"
 	"sync"
-	"sync/atomic"
 	"testing"
 	"time"
 
@@ -41,6 +40,7 @@ import (
 	"github.com/prometheus/prometheus/prompb"
 	"github.com/prometheus/prometheus/tsdb/record"
 	"github.com/prometheus/prometheus/util/testutil"
+	"go.uber.org/atomic"
 )
 
 const defaultFlushDeadline = 1 * time.Minute
@@ -336,7 +336,7 @@ func TestShouldReshard(t *testing.T) {
 		m.numShards = c.startingShards
 		m.samplesIn.incr(c.samplesIn)
 		m.samplesOut.incr(c.samplesOut)
-		m.lastSendTimestamp = c.lastSendTimestamp
+		m.lastSendTimestamp.Store(c.lastSendTimestamp)
 
 		m.Start()
 
@@ -497,7 +497,7 @@ func (c *TestWriteClient) Endpoint() string {
 // point the `numCalls` property will contain a count of how many times Store()
 // was called.
 type TestBlockingWriteClient struct {
-	numCalls uint64
+	numCalls atomic.Uint64
 }
 
 func NewTestBlockedWriteClient() *TestBlockingWriteClient {
@@ -505,13 +505,13 @@ func NewTestBlockedWriteClient() *TestBlockingWriteClient {
 }
 
 func (c *TestBlockingWriteClient) Store(ctx context.Context, _ []byte) error {
-	atomic.AddUint64(&c.numCalls, 1)
+	c.numCalls.Inc()
 	<-ctx.Done()
 	return nil
 }
 
 func (c *TestBlockingWriteClient) NumCalls() uint64 {
-	return atomic.LoadUint64(&c.numCalls)
+	return c.numCalls.Load()
 }
 
 func (c *TestBlockingWriteClient) Name() string {
@@ -667,7 +667,7 @@ func TestCalculateDesiredShards(t *testing.T) {
 		highestSent := startedAt.Add(ts - time.Duration(pendingSamples/inputRate)*time.Second)
 		m.metrics.highestSentTimestamp.Set(float64(highestSent.Unix()))
 
-		atomic.StoreInt64(&m.lastSendTimestamp, time.Now().Unix())
+		m.lastSendTimestamp.Store(time.Now().Unix())
 	}
 
 	ts := time.Duration(0)