decomposedfs: configurable filelock duration factor

changelog/unreleased/filelock-duration-factor.md

@@ -0,0 +1,5 @@
+Enhancement: configurable filelock duration factor in decomposedfs
+
+The lock cycle duration factor in decomposedfs can now be changed by setting `lock_cycle_duration_factor`.
+
+https://github.com/cs3org/reva/pull/3493

pkg/storage/utils/decomposedfs/decomposedfs.go

@@ -137,6 +137,10 @@ func New(o *options.Options, lu *lookup.Lookup, p PermissionsChecker, tp Tree, p
 		filelocks.SetMaxLockCycles(o.MaxAcquireLockCycles)
 	}
 
+	if o.LockCycleDurationFactor != 0 {
+		filelocks.SetLockCycleDurationFactor(o.LockCycleDurationFactor)
+	}
+
 	return &Decomposedfs{
 		tp:                tp,
 		lu:                lu,

pkg/storage/utils/decomposedfs/options/options.go

@@ -53,7 +53,8 @@ type Options struct {
 	PersonalSpaceAliasTemplate string `mapstructure:"personalspacealias_template"`
 	GeneralSpaceAliasTemplate  string `mapstructure:"generalspacealias_template"`
 
-	MaxAcquireLockCycles int `mapstructure:"max_acquire_lock_cycles"`
+	MaxAcquireLockCycles    int `mapstructure:"max_acquire_lock_cycles"`
+	LockCycleDurationFactor int `mapstructure:"lock_cycle_duration_factor"`
 }
 
 // New returns a new Options instance for the given configuration

pkg/storage/utils/filelocks/filelocks.go

@@ -32,9 +32,12 @@ import (
 const LockFileSuffix = ".flock"
 
 var (
-	_localLocks      sync.Map
-	_lockCycles      sync.Once
-	_lockCyclesValue = 25
+	_localLocks sync.Map
+	// waiting 20 lock cycles with a factor of 30 yields 6300ms, or a little over 6 sec
+	_lockCycles              sync.Once
+	_lockCyclesValue         = 20
+	_lockCycleDuration       sync.Once
+	_lockCycleDurationFactor = 30
 
 	// ErrPathEmpty indicates that no path was specified
 	ErrPathEmpty = errors.New("lock path is empty")
@@ -49,6 +52,13 @@ func SetMaxLockCycles(v int) {
 	})
 }
 
+// SetLockCycleDurationFactor configures the factor applied to the timeout allowed during a lock cycle. Subsequent calls to SetLockCycleDurationFactor have no effect
+func SetLockCycleDurationFactor(v int) {
+	_lockCycleDuration.Do(func() {
+		_lockCycleDurationFactor = v
+	})
+}
+
 // getMutexedFlock returns a new Flock struct for the given file.
 // If there is already one in the local store, it returns nil.
 // The caller has to wait until it can get a new one out of this
@@ -93,7 +103,7 @@ func acquireLock(file string, write bool) (*flock.Flock, error) {
 		if flock = getMutexedFlock(n); flock != nil {
 			break
 		}
-		w := time.Duration(i*3) * time.Millisecond
+		w := time.Duration(i*_lockCycleDurationFactor) * time.Millisecond
 
 		time.Sleep(w)
 	}
@@ -113,7 +123,7 @@ func acquireLock(file string, write bool) (*flock.Flock, error) {
 			break
 		}
 
-		time.Sleep(time.Duration(i*3) * time.Millisecond)
+		time.Sleep(time.Duration(i*_lockCycleDurationFactor) * time.Millisecond)
 	}
 
 	if !ok {

pkg/storage/utils/filelocks/filelocks_test.go

@@ -32,6 +32,7 @@ func TestAcquireWriteLock(t *testing.T) {
 	defer fin()
 
 	filelocks.SetMaxLockCycles(90)
+	filelocks.SetLockCycleDurationFactor(3)
 
 	var wg sync.WaitGroup
 	for i := 0; i < 10; i++ {
@@ -61,6 +62,7 @@ func TestAcquireReadLock(t *testing.T) {
 	defer fin()
 
 	filelocks.SetMaxLockCycles(90)
+	filelocks.SetLockCycleDurationFactor(3)
 
 	var wg sync.WaitGroup
 	for i := 0; i < 10; i++ {
@@ -86,6 +88,40 @@ func TestAcquireReadLock(t *testing.T) {
 	wg.Wait()
 }
 
+/* This negative test is flaky as 8000 goroutines are not enough to trigger this in ci
+func TestAcquireReadLockFail(t *testing.T) {
+	file, fin, _ := filelocks.FileFactory()
+	defer fin()
+
+	filelocks.SetMaxLockCycles(1)
+	filelocks.SetLockCycleDurationFactor(1)
+
+	// create a channel big enough for all waiting groups
+	errors := make(chan error, 8000)
+	var wg sync.WaitGroup
+	for i := 0; i < 8000; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+
+			l, err := filelocks.AcquireReadLock(file)
+			if err != nil {
+				// collect the error in a channel
+				errors <- err
+				return
+			}
+			err = filelocks.ReleaseLock(l)
+			assert.Nil(t, err)
+		}()
+	}
+
+	// at least one error should have occurred
+	assert.NotNil(t, <-errors)
+
+	wg.Wait()
+}
+*/
+
 func TestReleaseLock(t *testing.T) {
 	file, fin, _ := filelocks.FileFactory()
 	defer fin()