feat(storage): adding bucket-specific dynamicDelay

storage/dynamic_delay.go

@@ -36,6 +36,23 @@ type dynamicDelay struct {
  mu *sync.RWMutex
 }
 
+// validateDynamicDelayParams ensures,
+// targetPercentile is a valid fraction (between 0 and 1).
+// increaseRate is a positive number.
+// minDelay is less than maxDelay.
+func validateDynamicDelayParams(targetPercentile, increaseRate float64, minDelay, maxDelay time.Duration) error {
+ if targetPercentile < 0 || targetPercentile > 1 {
+ return fmt.Errorf("invalid targetPercentile (%v): must be within [0, 1]", targetPercentile)
+ }
+ if increaseRate <= 0 {
+ return fmt.Errorf("invalid increaseRate (%v): must be > 0", increaseRate)
+ }
+ if minDelay >= maxDelay {
+ return fmt.Errorf("invalid minDelay (%v) and maxDelay (%v) combination: minDelay must be smaller than maxDelay", minDelay, maxDelay)
+ }
+ return nil
+}
+
 // NewDynamicDelay returns a dynamicDelay.
 //
 // targetPercentile is the desired percentile to be computed. For example, a
@@ -49,16 +66,7 @@ type dynamicDelay struct {
 //
 // decrease can never lower the delay past minDelay, increase can never raise
 // the delay past maxDelay.
-func newDynamicDelay(targetPercentile float64, increaseRate float64, initialDelay, minDelay, maxDelay time.Duration) (*dynamicDelay, error) {
- if targetPercentile < 0 || targetPercentile > 1 {
- return nil, fmt.Errorf("invalid targetPercentile (%v): must be within [0, 1]", targetPercentile)
- }
- if increaseRate <= 0 {
- return nil, fmt.Errorf("invalid increaseRate (%v): must be > 0", increaseRate)
- }
- if minDelay >= maxDelay {
- return nil, fmt.Errorf("invalid minDelay (%v) and maxDelay (%v) combination: minDelay must be smaller than maxDelay", minDelay, maxDelay)
- }
+func newDynamicDelay(targetPercentile float64, increaseRate float64, initialDelay, minDelay, maxDelay time.Duration) *dynamicDelay {
  if initialDelay < minDelay {
  initialDelay = minDelay
  }
@@ -84,7 +92,7 @@ func newDynamicDelay(targetPercentile float64, increaseRate float64, initialDela
  maxDelay: maxDelay,
  value: initialDelay,
  mu: &sync.RWMutex{},
- }, nil
+ }
 }
 
 func (d *dynamicDelay) unsafeIncrease() {
@@ -141,7 +149,7 @@ func (d *dynamicDelay) getValue() time.Duration {
  return d.value
 }
 
-// PrintDelay prints the state of delay, helpful in debugging.
+// printDelay prints the state of delay, helpful in debugging.
 func (d *dynamicDelay) printDelay() {
  d.mu.RLock()
  defer d.mu.RUnlock()
@@ -152,3 +160,78 @@ func (d *dynamicDelay) printDelay() {
  fmt.Println("MaxDelay: ", d.maxDelay)
  fmt.Println("Value: ", d.value)
 }
+
+// bucketDelayManager wraps dynamicDelay to provide bucket-specific delays.
+type bucketDelayManager struct {
+ targetPercentile float64
+ increaseRate float64
+ initialDelay time.Duration
+ minDelay time.Duration
+ maxDelay time.Duration
+
+ // delays maps bucket names to their dynamic delay instance.
+ delays map[string]*dynamicDelay
+
+ // mu guards delays.
+ mu *sync.RWMutex
+}
+
+// newBucketDelayManager returns a new bucketDelayManager instance.
+func newBucketDelayManager(targetPercentile float64, increaseRate float64, initialDelay, minDelay, maxDelay time.Duration) (*bucketDelayManager, error) {
+ err := validateDynamicDelayParams(targetPercentile, increaseRate, minDelay, maxDelay)
+ if err != nil {
+ return nil, err
+ }
+
+ return &bucketDelayManager{
+ targetPercentile: targetPercentile,
+ increaseRate: increaseRate,
+ initialDelay: initialDelay,
+ minDelay: minDelay,
+ maxDelay: maxDelay,
+ delays: make(map[string]*dynamicDelay),
+ mu: &sync.RWMutex{},
+ }, nil
+}
+
+// getDelay retrieves the dynamicDelay instance for the given bucket name. If no delay
+// exists for the bucket, a new one is created with the configured parameters.
+func (b *bucketDelayManager) getDelay(bucketName string) *dynamicDelay {
+ b.mu.RLock()
+ delay, ok := b.delays[bucketName]
+ b.mu.RUnlock()
+
+ if !ok {
+ b.mu.Lock()
+ defer b.mu.Unlock()
+
+ // Check again, as someone might create b/w the execution of mu.RUnlock() and mu.Lock().
+ delay, ok = b.delays[bucketName]
+ if !ok {
+ // Create a new dynamicDelay for the bucket if it doesn't exist
+ delay = newDynamicDelay(b.targetPercentile, b.increaseRate, b.initialDelay, b.minDelay, b.maxDelay)
+ b.delays[bucketName] = delay
+ }
+ }
+ return delay
+}
+
+// increase notes that the operation took longer than the delay for the given bucket.
+func (b *bucketDelayManager) increase(bucketName string) {
+ b.getDelay(bucketName).increase()
+}
+
+// decrease notes that the operation completed before the delay for the given bucket.
+func (b *bucketDelayManager) decrease(bucketName string) {
+ b.getDelay(bucketName).decrease()
+}
+
+// update updates the delay value for the bucket depending on the specified latency.
+func (b *bucketDelayManager) update(bucketName string, latency time.Duration) {
+ b.getDelay(bucketName).update(latency)
+}
+
+// getValue returns the desired delay to wait before retrying the operation for the given bucket.
+func (b *bucketDelayManager) getValue(bucketName string) time.Duration {
+ return b.getDelay(bucketName).getValue()
+}