Revert changes to EC backoff introduced in #382 (#399)

* Revert the ECPeriod changes (#382)

Signed-off-by: Jakub Sztandera <[email protected]>

* Revert changes to EC backoff introduced in #382

Additionally move backoff params to manifest

Signed-off-by: Jakub Sztandera <[email protected]>

* Fix manifest in tests

Signed-off-by: Jakub Sztandera <[email protected]>

* Change max backoff to 15min

Signed-off-by: Jakub Sztandera <[email protected]>

---------

Signed-off-by: Jakub Sztandera <[email protected]>

host.go

@@ -320,36 +320,29 @@ func (h *gpbftHost) ReceiveDecision(decision *gpbft.Justification) time.Time {
 	h.log.Infof("got decision at instance %d, finalized head at epoch: %d",
 		decision.Vote.Instance, decision.Vote.Value.Head().Epoch)
 	err := h.saveDecision(decision)
+
+	manifest := h.manifest.Manifest()
+	ecDelay := time.Duration(manifest.ECDelayMultiplier * float64(manifest.ECPeriod))
+
 	if err != nil {
 		h.log.Errorf("error while saving decision: %+v", err)
 	}
 	ts, err := h.client.ec.GetTipset(h.runningCtx, decision.Vote.Value.Head().Key)
 	if err != nil {
+		// this should not happen
 		h.log.Errorf("could not get timestamp of just finalized tipset: %+v", err)
-		// We use the period, not the delay, because we expect to start an instance once per
-		// period and we just finished the last instance.
-		return time.Now().Add(h.manifest.Manifest().ECPeriod)
+		return time.Now().Add(ecDelay)
 	}
 
 	if decision.Vote.Value.HasSuffix() {
-		// we decided on something new, use just the ECDelay plus the period.
-		return ts.Timestamp().Add(h.manifest.Manifest().ECPeriod + h.manifest.Manifest().ECDelay)
+		// we decided on something new, the tipset that got finalized can at minimum be 30-60s old.
+		return ts.Timestamp().Add(ecDelay)
 	}
-
-	// we decided on base, calculate how much we should back off
-	// all of this should go into manifest but I think Alfonso dislikes me already :P
-	const (
-		minBackoff = 2.
-		maxBackoff = 20. // 10m with 30s ECPeriod
-	)
-	// the backoff is defined in multiples of ECPeriod starting at the last finalized tipset
-	// each additional base decision beyond that will incurr the maxBackoff
-	var backoffTable = []float64{1, 1.3, 1.69, 2.197, 2.8561, 3.71293, 3.71293, 4.826809, 6.2748517, 8.15730721} // 1.3^i+1 backoff, table for more flexibility
-	//TODO move all the above to manifest
+	backoffTable := manifest.BaseDecisionBackoffTable
 
 	attempts := 0
-	var backoffMultipler float64
-	for instance := decision.Vote.Instance - 1; instance > h.manifest.Manifest().InitialInstance; instance-- {
+	backoffMultipler := 1.0 // to account for the one ECDelay after which we got the base decistion
+	for instance := decision.Vote.Instance - 1; instance > manifest.InitialInstance; instance-- {
 		cert, err := h.client.certStore.Get(h.runningCtx, instance)
 		if err != nil {
 			h.log.Errorf("error while getting instance %d from certstore: %+v", instance, err)
@@ -359,13 +352,14 @@ func (h *gpbftHost) ReceiveDecision(decision *gpbft.Justification) time.Time {
 			attempts += 1
 		}
 		if attempts < len(backoffTable) {
-			backoffMultipler += min(backoffTable[attempts], maxBackoff)
+			backoffMultipler += backoffTable[attempts]
 		} else {
-			backoffMultipler += maxBackoff
+			// if we are beyond backoffTable, reuse the last element
+			backoffMultipler += backoffTable[len(backoffTable)-1]
 		}
 	}
 
-	backoff := h.manifest.Manifest().ECDelay + time.Duration(float64(h.manifest.Manifest().ECPeriod)*backoffMultipler)
+	backoff := time.Duration(float64(ecDelay) * backoffMultipler)
 	h.log.Infof("backing off for: %v", backoff)
 
 	return ts.Timestamp().Add(backoff)

manifest/manifest.go

@@ -18,10 +18,12 @@ import (
 var (
 	// Default configuration for the EC Backend
 	DefaultEcConfig = &EcConfig{
-		ECFinality:       900,
-		CommiteeLookback: 5,
-		ECDelay:          60 * time.Second,
-		ECPeriod:         30 * time.Second,
+		ECFinality:        900,
+		CommiteeLookback:  5,
+		ECPeriod:          30 * time.Second,
+		ECDelayMultiplier: 2.,
+		// MaxBackoff is 15min given default params
+		BaseDecisionBackoffTable: []float64{1.3, 1.69, 2.2, 2.86, 3.71, 4.83, 6.27, 7.5},
 	}
 
 	DefaultGpbftConfig = &GpbftConfig{
@@ -60,12 +62,16 @@ type GpbftConfig struct {
 }
 
 type EcConfig struct {
-	ECFinality int64
-	// The delay after a tipset is produced before we attempt to finalize it.
-	ECDelay time.Duration
 	// The delay between tipsets.
-	ECPeriod         time.Duration
-	CommiteeLookback uint64
+	ECPeriod time.Duration
+	// Number of epochs required to reach EC defined fianlity
+	ECFinality int64
+	// The multiplier on top of the ECPeriod of the time we will wait before starting a new instance,
+	// referencing the timestampt of the latest finalized tipset.
+	ECDelayMultiplier float64
+	// Table of incremental multipliers to backoff in units of ECDelay in case of base decisions
+	BaseDecisionBackoffTable []float64
+	CommiteeLookback         uint64
 }
 
 // Manifest identifies the specific configuration for

manifest/manifest_test.go

@@ -37,11 +37,11 @@ var base manifest.Manifest = manifest.Manifest{
 		MaxLookaheadRounds:   10,
 	},
 	EcConfig: &manifest.EcConfig{
-		ECFinality:       900,
-		CommiteeLookback: 5,
-		ECDelay:          30 * time.Second,
-
-		ECPeriod: 30 * time.Second,
+		ECFinality:               900,
+		CommiteeLookback:         5,
+		ECDelayMultiplier:        2.0,
+		ECPeriod:                 30 * time.Second,
+		BaseDecisionBackoffTable: []float64{1.3, 1.69, 2.2, 2.86, 3.71, 4.83, 6.27, 8.16, 10.6, 13.79, 15.},
 	},
 }
 

test/f3_test.go

@@ -173,8 +173,9 @@ var base manifest.Manifest = manifest.Manifest{
 		ECFinality:       10,
 		CommiteeLookback: 5,
 		// increased delay and period to accelerate test times.
-		ECDelay:  500 * time.Millisecond,
-		ECPeriod: 500 * time.Millisecond,
+		ECPeriod:                 500 * time.Millisecond,
+		ECDelayMultiplier:        1.0,
+		BaseDecisionBackoffTable: []float64{1.3, 1.69, 2.2, 2.86, 3.71, 4.83, 6.27, 8.16, 10.6, 13.79, 15.},
 	},
 }