fix(inflight): reduce memory footprint by using struct{} instead of bool

Makefile

@@ -43,3 +43,6 @@ check: check-golangci
 # fix make all static code analysis tools to fix the issues
 .PHONY: fix
 fix: fix-golangci
+
+.PHONY: test
+test: go test -v -race ./...

inflight/inflight.go

@@ -36,7 +36,7 @@ func New() InFlight {
 
 func newSyncU64set(limit uint64) *syncU64set {
 	return &syncU64set{
-		values:  make(map[uint64]bool),
+		values:  make(map[uint64]struct{}),
 		limit:   limit,
 		deleted: 0,
 		lock:    sync.RWMutex{},
@@ -75,7 +75,7 @@ func (s *shardedSyncU64set) AddIfNotPresent(v uint64) bool {
 }
 
 type syncU64set struct {
-	values  map[uint64]bool
+	values  map[uint64]struct{}
 	deleted uint64
 	limit   uint64
 	lock    sync.RWMutex
@@ -95,7 +95,7 @@ func (s *syncU64set) AddIfNotPresent(u uint64) bool {
 	if ok {
 		return false
 	}
-	s.values[u] = true
+	s.values[u] = struct{}{}
 	return true
 }
 
@@ -127,17 +127,14 @@ func (s *syncU64set) addDeleted(n uint64) {
 func (s *syncU64set) shrink() {
 	s.lock.Lock()
 	defer s.lock.Unlock()
-	var newValues map[uint64]bool
+	mapLen := uint64(0)
 	if uint64(len(s.values)) >= s.deleted {
-		newValues = make(map[uint64]bool, uint64(len(s.values))-s.deleted)
-	} else {
-		newValues = make(map[uint64]bool, 0)
+		mapLen = uint64(len(s.values)) - s.deleted
 	}
+	newValues := make(map[uint64]struct{}, mapLen)
 
 	for key, val := range s.values {
-		if val {
-			newValues[key] = val
-		}
+		newValues[key] = val
 	}
 	s.values = newValues
 	s.deleted = 0

inflight/inflight_test.go

@@ -19,6 +19,7 @@ import (
 	"reflect"
 	"testing"
 	"testing/quick"
+	"time"
 )
 
 func TestAddIfNotPresent(t *testing.T) {
@@ -82,6 +83,25 @@ func TestInflight(t *testing.T) {
 	}
 }
 
+//go:norace
+func TestAutoShrink(t *testing.T) {
+	t.Parallel()
+	flight := newSyncU64set(10)
+	for x := uint64(0); x < 11; x++ {
+		flight.AddIfNotPresent(x)
+	}
+	if len(flight.values) != 11 {
+		t.Fatal("expect 11 records in flight, but got ", len(flight.values))
+	}
+	for x := uint64(0); x < 11; x++ {
+		flight.Delete(x)
+	}
+	time.Sleep(time.Second / 2)
+	if flight.deleted != 0 {
+		t.Fatal("expect that shrink is been executed and deleted dropped back to 0, but got ", flight.deleted)
+	}
+}
+
 func TestInflightSharded(t *testing.T) {
 	t.Parallel()
 	flight := newShardedSyncU64set()