feature(locking): add proper locking and overhaul existing locking service (#34)

Reviewed-on: #34
Co-authored-by: Varakh <varakh@varakh.de>
Co-committed-by: Varakh <varakh@varakh.de>

README.md

@@ -37,6 +37,34 @@ LOGGING_LEVEL=debug
 
 Please look into the `_doc/` folder for [OpenAPI specification](./_doc/api.yaml) and a Postman Collection.
 
+### Lock service
+
+The `lockService` can be used to lock resources. This works in-memory and also in a distributed fashion with REDIS.
+
+Ensure to provide proper locking options when using, although in-memory ignores those. 
+
+Example:
+
+```shell
+# invoked from an endpoint
+context := c.Request.Context()
+
+var err error
+var lock appLock
+
+if lock, err = h.lockService.lockWithOptions(context, "TEST-LOCK", withAppLockOptionExpiry(5*time.Minute), withAppLockOptionInfiniteRetries(), withAppLockOptionRetryDelay(5*time.Second)); err != nil {
+    _ = c.AbortWithError(errToHttpStatus(err), err)
+    return
+}
+# defer to avoid leakage
+defer func(lock appLock) {
+    _ = lock.unlock(context)
+}(lock)
+
+# simulate long running task
+time.Sleep(20 * time.Second)
+```
+
 ### Getting started
 
 1. Run `make clean dependencies` to fetch dependencies

go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/go-co-op/gocron-redis-lock/v2 v2.0.1
 	github.com/go-co-op/gocron/v2 v2.5.0
 	github.com/go-playground/validator/v10 v10.20.0
+	github.com/go-redsync/redsync/v4 v4.11.0
 	github.com/go-resty/resty/v2 v2.13.1
 	github.com/google/uuid v1.6.0
 	github.com/redis/go-redis/v9 v9.5.1
@@ -39,7 +40,6 @@ require (
 	github.com/gin-contrib/sse v0.1.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
-	github.com/go-redsync/redsync/v4 v4.11.0 // indirect
 	github.com/goccy/go-json v0.10.2 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-multierror v1.1.1 // indirect

server/app.go

@@ -49,7 +49,18 @@ func Start() {
 	actionRepo := newActionDbRepo(env.db)
 	actionInvocationRepo := newActionInvocationDbRepo(env.db)
 
-	lockService := newLockMemService()
+	var lockService lockService
+
+	if env.lockConfig.redisEnabled {
+		var err error
+		lockService, err = newLockRedisService(env.lockConfig)
+
+		if err != nil {
+			zap.L().Fatal("Failed to create lock service", zap.Error(err))
+		}
+	} else {
+		lockService = newLockMemService()
+	}
 
 	eventService := newEventService(eventRepo)
 	updateService := newUpdateService(updateRepo, eventService)

server/service_lock.go

@@ -1,9 +1,65 @@
 package server
 
+import (
+	"context"
+	"math"
+	"time"
+)
+
+// lockService provides methods for locking resources, behavior depends on underlying implementation
 type lockService interface {
-	init() error
-	tryLock(resource string) error
-	release(resource string) error
-	exists(resource string) bool
-	stop()
+	// lock locks a resource applying default options (varies for implementations)
+	lock(ctx context.Context, resource string) (appLock, error)
+
+	// lockWithOptions locks a resource with given options, not all options are applied (varies for implementations)
+	lockWithOptions(ctx context.Context, resource string, options ...appLockOption) (appLock, error)
+}
+
+type appLock interface {
+	// unlock unlocks a lock
+	unlock(ctx context.Context) error
+}
+
+type appLockOption interface {
+	apply(l *appLockOptions)
+}
+
+type appLockOptionFunc func(o *appLockOptions)
+
+func (f appLockOptionFunc) apply(o *appLockOptions) {
+	f(o)
+}
+
+type appLockOptions struct {
+	expiry     *time.Duration
+	retryDelay *time.Duration
+	maxRetries *int
+}
+
+func withAppLockOptionExpiry(expiry time.Duration) appLockOption {
+	return appLockOptionFunc(func(o *appLockOptions) {
+		o.expiry = &expiry
+	})
+}
+
+func withAppLockOptionRetries(retries int) appLockOption {
+	return appLockOptionFunc(func(o *appLockOptions) {
+		o.maxRetries = &retries
+	})
+}
+
+var (
+	appLockOptionMaxRetries = math.MaxInt32
+)
+
+func withAppLockOptionInfiniteRetries() appLockOption {
+	return appLockOptionFunc(func(o *appLockOptions) {
+		o.maxRetries = &appLockOptionMaxRetries
+	})
+}
+
+func withAppLockOptionRetryDelay(retryDelay time.Duration) appLockOption {
+	return appLockOptionFunc(func(o *appLockOptions) {
+		o.retryDelay = &retryDelay
+	})
 }

server/service_lock_mem.go

@@ -1,52 +1,75 @@
 package server
 
 import (
+	"context"
+	"errors"
 	"git.myservermanager.com/varakh/upda/util"
 	"go.uber.org/zap"
+	"time"
 )
 
 type lockMemService struct {
 	registry *util.InMemoryLockRegistry
 }
 
+var (
+	errLockMemNotReleased = newServiceError(Conflict, errors.New("lock service: could not release lock"))
+)
+
 func newLockMemService() lockService {
+	zap.L().Info("Initialized in-memory locking service")
 	return &lockMemService{registry: util.NewInMemoryLockRegistry()}
 }
 
-func (s *lockMemService) init() error {
-	zap.L().Info("Initialized in-memory locking service")
-	return nil
+// lock locks a given resource without any options (default expiration)
+func (s *lockMemService) lock(ctx context.Context, resource string) (appLock, error) {
+	return s.lockWithOptions(ctx, resource, withAppLockOptionExpiry(0))
 }
 
-func (s *lockMemService) tryLock(resource string) error {
+// lockWithOptions locks a given resource, only TTL as option is supported
+func (s *lockMemService) lockWithOptions(ctx context.Context, resource string, options ...appLockOption) (appLock, error) {
 	if resource == "" {
-		return errorValidationNotBlank
+		return nil, errorValidationNotBlank
+	}
+
+	var expiration time.Duration = 0
+	if options != nil {
+		lockOptions := &appLockOptions{}
+		for _, o := range options {
+			o.apply(lockOptions)
+		}
+
+		if lockOptions.expiry != nil {
+			expiration = *lockOptions.expiry
+		}
 	}
 
 	zap.L().Sugar().Debugf("Trying to lock '%s'", resource)
-	s.registry.Lock(resource)
+
+	s.registry.LockWithTTL(resource, expiration)
+
 	zap.L().Sugar().Debugf("Locked '%s'", resource)
 
-	return nil
-}
-
-func (s *lockMemService) release(resource string) error {
-	if resource == "" {
-		return errorValidationNotBlank
+	l := &inMemoryLock{
+		registry: s.registry,
+		resource: resource,
 	}
 
-	zap.L().Sugar().Debugf("Releasing lock '%s'", resource)
-	err := s.registry.Unlock(resource)
-	zap.L().Sugar().Debugf("Released lock '%s'", resource)
-
-	return err
+	return l, nil
 }
 
-func (s *lockMemService) exists(resource string) bool {
-	return s.registry.Exists(resource)
+var _ appLock = (*inMemoryLock)(nil)
+
+type inMemoryLock struct {
+	registry *util.InMemoryLockRegistry
+	resource string
 }
 
-func (s *lockMemService) stop() {
-	zap.L().Info("Clearing in-memory locking service")
-	s.registry.Clear()
+func (r inMemoryLock) unlock(ctx context.Context) error {
+	zap.L().Sugar().Debugf("Unlocking '%s'", r.resource)
+
+	if err := r.registry.Unlock(r.resource); err != nil {
+		return errLockMemNotReleased
+	}
+	return nil
 }

server/service_lock_mem_test.go

@@ -0,0 +1,29 @@
+package server
+
+import (
+	"context"
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"time"
+)
+
+const (
+	testLockName = "test_lock"
+)
+
+func TestLockExpiresAndCannotBeReleased(t *testing.T) {
+	a := assert.New(t)
+
+	s := newLockMemService()
+	ctx := context.Background()
+
+	lock, lockErr := s.lockWithOptions(ctx, testLockName, withAppLockOptionExpiry(250*time.Millisecond))
+	a.Nil(lockErr)
+	a.NotNil(lock)
+
+	time.Sleep(251 * time.Millisecond)
+
+	unlockErr := lock.unlock(ctx)
+	a.NotNil(unlockErr)
+	a.ErrorContains(unlockErr, "could not release lock")
+}

server/service_lock_redis.go

@@ -0,0 +1,109 @@
+package server
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"github.com/go-redsync/redsync/v4"
+	redsyncgoredis "github.com/go-redsync/redsync/v4/redis/goredis/v9"
+	"github.com/redis/go-redis/v9"
+	"go.uber.org/zap"
+)
+
+type lockRedisService struct {
+	rs *redsync.Redsync
+}
+
+var (
+	errLockRedisNotObtained = newServiceError(Conflict, errors.New("lock service: could not obtain lock"))
+	errLockRedisNotReleased = newServiceError(Conflict, errors.New("lock service: could not release lock"))
+)
+
+func newLockRedisService(lc *lockConfig) (lockService, error) {
+	zap.L().Info("Initialized REDIS locking service")
+
+	var err error
+	var redisOptions *redis.Options
+	redisOptions, err = redis.ParseURL(lc.redisUrl)
+
+	if err != nil {
+		zap.L().Sugar().Fatalf("Cannot parse REDIS URL '%s' to set up locking. Reason: %s", lc.redisUrl, err.Error())
+	}
+
+	c := redis.NewClient(redisOptions)
+	if err = c.Ping(context.Background()).Err(); err != nil {
+		return nil, newServiceError(General, fmt.Errorf("lock service: failed to connect to REDIS. Reason: %w", err))
+	}
+
+	pool := redsyncgoredis.NewPool(c)
+	rs := redsync.New(pool)
+
+	return &lockRedisService{rs: rs}, nil
+}
+
+// lock locks a given resource without any options
+func (s *lockRedisService) lock(ctx context.Context, resource string) (appLock, error) {
+	return s.lockWithOptions(ctx, resource, nil)
+}
+
+// lockWithOptions locks a given resource considering all options
+func (s *lockRedisService) lockWithOptions(ctx context.Context, resource string, options ...appLockOption) (appLock, error) {
+	if resource == "" {
+		return nil, errorValidationNotBlank
+	}
+
+	var rsOptions []redsync.Option
+
+	if options != nil {
+		lockOptions := &appLockOptions{}
+		for _, o := range options {
+			o.apply(lockOptions)
+		}
+
+		if lockOptions.expiry != nil {
+			rsOptions = append(rsOptions, redsync.WithExpiry(*lockOptions.expiry))
+		}
+		if lockOptions.maxRetries != nil {
+			rsOptions = append(rsOptions, redsync.WithTries(*lockOptions.maxRetries))
+		}
+		if lockOptions.retryDelay != nil {
+			rsOptions = append(rsOptions, redsync.WithRetryDelay(*lockOptions.retryDelay))
+		}
+	}
+
+	mu := s.rs.NewMutex(resource, rsOptions...)
+
+	zap.L().Sugar().Debugf("Trying to lock '%s'", resource)
+
+	if err := mu.LockContext(ctx); err != nil {
+		return nil, errLockRedisNotObtained
+	}
+
+	zap.L().Sugar().Debugf("Locked '%s'", resource)
+
+	l := &redisLock{
+		mu: mu,
+	}
+
+	return l, nil
+}
+
+var _ appLock = (*redisLock)(nil)
+
+type redisLock struct {
+	mu *redsync.Mutex
+}
+
+func (r redisLock) unlock(ctx context.Context) error {
+	zap.L().Sugar().Debugf("Unlocking '%s'", r.mu.Name())
+
+	unlocked, err := r.mu.UnlockContext(ctx)
+	if err != nil {
+		return errLockRedisNotReleased
+	}
+	if !unlocked {
+		return errLockRedisNotReleased
+	}
+
+	return nil
+}

server/service_task.go

@@ -26,12 +26,12 @@ type taskService struct {
 }
 
 const (
-	JobUpdatesCleanStale = "UPDATES_CLEAN_STALE"
-	JobEventsCleanStale  = "EVENTS_CLEAN_STALE"
-	JobActionsEnqueue    = "ACTIONS_ENQUEUE"
-	JobActionsInvoke     = "ACTIONS_INVOKE"
-	JobActionsCleanStale = "ACTIONS_CLEAN_STALE"
-	JobPrometheusRefresh = "PROMETHEUS_REFRESH"
+	jobUpdatesCleanStale = "UPDATES_CLEAN_STALE"
+	jobEventsCleanStale  = "EVENTS_CLEAN_STALE"
+	jobActionsEnqueue    = "ACTIONS_ENQUEUE"
+	jobActionsInvoke     = "ACTIONS_INVOKE"
+	jobActionsCleanStale = "ACTIONS_CLEAN_STALE"
+	jobPrometheusRefresh = "PROMETHEUS_REFRESH"
 )
 
 var (
@@ -69,7 +69,7 @@ func newTaskService(u *updateService, e *eventService, w *webhookService, a *act
 		redisClient := redis.NewClient(redisOptions)
 
 		var locker gocron.Locker
-		if locker, err = redislock.NewRedisLocker(redisClient, redislock.WithTries(1)); err != nil {
+		if locker, err = redislock.NewRedisLocker(redisClient, redislock.WithTries(1), redislock.WithExpiry(30*time.Second), redislock.WithRetryDelay(5*time.Second)); err != nil {
 			zap.L().Sugar().Fatalf("Cannot set up REDIS locker. Reason: %s", err.Error())
 		}
 
@@ -111,7 +111,6 @@ func (s *taskService) stop() {
 	if err := s.scheduler.Shutdown(); err != nil {
 		zap.L().Sugar().Warnf("Cannot shut down scheduler. Reason: %v", err)
 	}
-	s.lockService.stop()
 	zap.L().Info("Stopped all periodic tasks")
 }
 
@@ -145,7 +144,7 @@ func (s *taskService) configureCleanupStaleUpdatesTask() {
 	}
 
 	scheduledJob := gocron.DurationJob(s.taskConfig.updateCleanStaleInterval)
-	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(JobUpdatesCleanStale)); err != nil {
+	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(jobUpdatesCleanStale)); err != nil {
 		zap.L().Sugar().Fatalf("Could not create task for cleaning stale updates. Reason: %s", err.Error())
 	}
 }
@@ -175,7 +174,7 @@ func (s *taskService) configureCleanupStaleEventsTask() {
 	}
 
 	scheduledJob := gocron.DurationJob(s.taskConfig.eventCleanStaleInterval)
-	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(JobEventsCleanStale)); err != nil {
+	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(jobEventsCleanStale)); err != nil {
 		zap.L().Sugar().Fatalf("Could not create task for cleaning stale events. Reason: %s", err.Error())
 	}
 }
@@ -192,7 +191,7 @@ func (s *taskService) configureActionsEnqueueTask() {
 	}
 
 	scheduledJob := gocron.DurationJob(s.taskConfig.actionsEnqueueInterval)
-	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(JobActionsEnqueue)); err != nil {
+	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(jobActionsEnqueue)); err != nil {
 		zap.L().Sugar().Fatalf("Could not create task for enqueueing actions. Reason: %s", err.Error())
 	}
 }
@@ -209,7 +208,7 @@ func (s *taskService) configureActionsInvokeTask() {
 	}
 
 	scheduledJob := gocron.DurationJob(s.taskConfig.actionsInvokeInterval)
-	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(JobActionsInvoke)); err != nil {
+	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(jobActionsInvoke)); err != nil {
 		zap.L().Sugar().Fatalf("Could not create task for invoking actions. Reason: %s", err.Error())
 	}
 }
@@ -246,7 +245,7 @@ func (s *taskService) configureCleanupStaleActionsTask() {
 	}
 
 	scheduledJob := gocron.DurationJob(s.taskConfig.actionsCleanStaleInterval)
-	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(JobActionsCleanStale)); err != nil {
+	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(jobActionsCleanStale)); err != nil {
 		zap.L().Sugar().Fatalf("Could not create task for cleaning stale actions. Reason: %s", err.Error())
 	}
 }
@@ -310,7 +309,7 @@ func (s *taskService) configurePrometheusRefreshTask() {
 	}
 
 	scheduledJob := gocron.DurationJob(s.taskConfig.prometheusRefreshInterval)
-	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(JobPrometheusRefresh)); err != nil {
+	if _, err := s.scheduler.NewJob(scheduledJob, gocron.NewTask(runnable), gocron.WithName(jobPrometheusRefresh)); err != nil {
 		zap.L().Sugar().Fatalf("Could not create task for refreshing prometheus. Reason: %s", err.Error())
 	}
 }

util/locker_memory.go

@@ -1,19 +1,28 @@
 package util
 
-import "sync"
+import (
+	"sync"
+	"time"
+)
 
 import (
 	"errors"
 	"sync/atomic"
 )
 
+const (
+	MemoryLockerDefaultExpiration time.Duration = 0
+	MemoryLockerNoExpiration                    = -1
+)
+
 // ErrorNoSuchLock is returned when the requested lock does not exist
 var ErrorNoSuchLock = errors.New("no such lock")
 
 // InMemoryLockRegistry provides a locking mechanism based on the passed in reference name
 type InMemoryLockRegistry struct {
-	mu    sync.Mutex
-	locks map[string]*lockCtr
+	mu            sync.Mutex
+	locks         map[string]*lockCtr
+	defaultExpiry int64
 }
 
 // lockCtr is used by InMemoryLockRegistry to represent a lock with a given name.
@@ -22,6 +31,8 @@ type lockCtr struct {
 	// waiters is the number of waiters waiting to acquire the lock
 	// this is int32 instead of uint32, so we can add `-1` in `dec()`
 	waiters int32
+	// expires is the time when
+	expires int64
 }
 
 // inc increments the number of waiters waiting for the lock
@@ -52,40 +63,55 @@ func (l *lockCtr) Unlock() {
 // NewInMemoryLockRegistry creates a new InMemoryLockRegistry
 func NewInMemoryLockRegistry() *InMemoryLockRegistry {
 	return &InMemoryLockRegistry{
-		locks: make(map[string]*lockCtr),
+		defaultExpiry: MemoryLockerNoExpiration,
+		locks:         make(map[string]*lockCtr),
 	}
 }
 
 // Clear clears all locks by initializing a new map
-func (l *InMemoryLockRegistry) Clear() {
-	l.locks = make(map[string]*lockCtr)
+func (r *InMemoryLockRegistry) Clear() {
+	r.locks = make(map[string]*lockCtr)
 }
 
 // Exists exists a lock by name
-func (l *InMemoryLockRegistry) Exists(name string) bool {
-	l.mu.Lock()
-	_, exists := l.locks[name]
-	l.mu.Unlock()
+func (r *InMemoryLockRegistry) Exists(name string) bool {
+	r.deleteExpired()
+	r.mu.Lock()
+	_, exists := r.locks[name]
+	r.mu.Unlock()
 	return exists
 }
 
-// Lock locks a mutex with the given name. If it doesn't exist, one is created
-func (l *InMemoryLockRegistry) Lock(name string) {
-	l.mu.Lock()
-	if l.locks == nil {
-		l.locks = make(map[string]*lockCtr)
+// Lock locks a mutex with the given name and no expiration. If it doesn't exist, one is created.
+func (r *InMemoryLockRegistry) Lock(name string) {
+	r.LockWithTTL(name, MemoryLockerDefaultExpiration)
+}
+
+// LockWithTTL locks a mutex with the given name and duration. If it doesn't exist, one is created. If duration is greater than 0, expiration is added.
+func (r *InMemoryLockRegistry) LockWithTTL(name string, duration time.Duration) {
+	r.deleteExpired()
+
+	r.mu.Lock()
+	if r.locks == nil {
+		r.locks = make(map[string]*lockCtr)
 	}
 
-	nameLock, exists := l.locks[name]
+	nameLock, exists := r.locks[name]
 	if !exists {
-		nameLock = &lockCtr{}
-		l.locks[name] = nameLock
+		e := r.defaultExpiry
+		if duration > 0 {
+			e = time.Now().Add(duration).UnixNano()
+		}
+
+		nameLock = &lockCtr{expires: e}
+
+		r.locks[name] = nameLock
 	}
 
 	// increment the nameLock waiters while inside the main mutex
 	// this makes sure that the lock isn't deleted if `Lock` and `Unlock` are called concurrently
 	nameLock.inc()
-	l.mu.Unlock()
+	r.mu.Unlock()
 
 	// Lock the nameLock outside the main mutex, so we don't block other operations
 	// once locked then we can decrement the number of waiters for this lock
@@ -95,19 +121,42 @@ func (l *InMemoryLockRegistry) Lock(name string) {
 
 // Unlock unlocks the mutex with the given name
 // If the given lock is not being waited on by any other callers, it is deleted
-func (l *InMemoryLockRegistry) Unlock(name string) error {
-	l.mu.Lock()
-	nameLock, exists := l.locks[name]
+func (r *InMemoryLockRegistry) Unlock(name string) error {
+	r.deleteExpired()
+
+	r.mu.Lock()
+	nameLock, exists := r.locks[name]
 	if !exists {
-		l.mu.Unlock()
+		r.mu.Unlock()
 		return ErrorNoSuchLock
 	}
 
 	if nameLock.count() == 0 {
-		delete(l.locks, name)
+		delete(r.locks, name)
 	}
 	nameLock.Unlock()
 
-	l.mu.Unlock()
+	r.mu.Unlock()
 	return nil
 }
+
+// deleteExpired deletes expired entries if their expiration value is greater than 0 (expiration enabled) and it expired. This is a costly operation and is guarded by the global registry mutex.
+func (r *InMemoryLockRegistry) deleteExpired() {
+	now := time.Now().UnixNano()
+	r.mu.Lock()
+	for k, v := range r.locks {
+		if v.expires > 0 && now > v.expires {
+			nameLock, exists := r.locks[k]
+
+			if !exists {
+				continue
+			}
+
+			if nameLock.count() == 0 {
+				delete(r.locks, k)
+			}
+			nameLock.Unlock()
+		}
+	}
+	r.mu.Unlock()
+}

util/locker_memory_test.go

@@ -0,0 +1,43 @@
+package util
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+	"time"
+)
+
+const (
+	testLockName = "test_lock"
+)
+
+func TestLockExpires(t *testing.T) {
+	a := assert.New(t)
+
+	r := NewInMemoryLockRegistry()
+	r.LockWithTTL(testLockName, 250*time.Millisecond)
+	a.True(r.Exists(testLockName))
+
+	time.Sleep(251 * time.Millisecond)
+	a.False(r.Exists(testLockName))
+}
+
+func TestLockNeverExpires(t *testing.T) {
+	a := assert.New(t)
+
+	r := NewInMemoryLockRegistry()
+	r.Lock(testLockName)
+	a.True(r.Exists(testLockName))
+
+	time.Sleep(2 * time.Second)
+	a.True(r.Exists(testLockName))
+}
+
+func TestLockLocksAndUnlocks(t *testing.T) {
+	a := assert.New(t)
+
+	r := NewInMemoryLockRegistry()
+	r.LockWithTTL(testLockName, 250*time.Millisecond)
+	a.True(r.Exists(testLockName))
+	_ = r.Unlock(testLockName)
+	a.False(r.Exists(testLockName))
+}