From 0570f4d02510059f4ecc7f2ccb8742a2cc574f75 Mon Sep 17 00:00:00 2001
From: Hans Moog <3293976+hmoog@users.noreply.github.com>
Date: Fri, 26 Apr 2024 03:30:29 +0200
Subject: [PATCH] Refactor: refactored flags

---
 pkg/protocol/chain.go  | 32 +++++++++++++++++---------------
 pkg/protocol/chains.go | 10 ++--------
 2 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/pkg/protocol/chain.go b/pkg/protocol/chain.go
index d8190ec96..2acbb4a68 100644
--- a/pkg/protocol/chain.go
+++ b/pkg/protocol/chain.go
@@ -20,6 +20,9 @@ type Chain struct {
 	// ParentChain contains the chain that this chain forked from.
 	ParentChain reactive.Variable[*Chain]
 
+	// DivergencePointVerified contains a flag that indicates whether the divergence point of this chain is verified.
+	DivergencePointVerified reactive.Event
+
 	// ChildChains contains the set of all chains that forked from this chain.
 	ChildChains reactive.Set[*Chain]
 
@@ -54,9 +57,6 @@ type Chain struct {
 	// Engine contains the engine instance that is used to process blocks for this chain.
 	Engine reactive.Variable[*engine.Engine]
 
-	// IsSolid contains a flag that indicates whether this chain is solid (has a connection to the root).
-	IsSolid reactive.Event
-
 	// IsEvicted contains a flag that indicates whether this chain was evicted.
 	IsEvicted reactive.Event
 
@@ -78,6 +78,7 @@ func newChain(chains *Chains) *Chain {
 	c := &Chain{
 		ForkingPoint:             reactive.NewVariable[*Commitment](),
 		ParentChain:              reactive.NewVariable[*Chain](),
+		DivergencePointVerified:  reactive.NewEvent(),
 		ChildChains:              reactive.NewSet[*Chain](),
 		LatestCommitment:         reactive.NewVariable[*Commitment](),
 		LatestAttestedCommitment: reactive.NewVariable[*Commitment](),
@@ -89,7 +90,6 @@ func newChain(chains *Chains) *Chain {
 		StartEngine:              reactive.NewVariable[bool](),
 		Engine:                   reactive.NewVariable[*engine.Engine](),
 		IsEvicted:                reactive.NewEvent(),
-		IsSolid:                  reactive.NewEvent(),
 		shouldEvict:              reactive.NewEvent(),
 
 		chains:      chains,
@@ -234,10 +234,10 @@ func (c *Chain) initDerivedProperties() (shutdown func()) {
 							parentChain.deriveChildChains(c),
 
 							c.deriveShouldEvict(forkingPoint, parentChain),
-
-							c.deriveIsSolid(forkingPoint, parentChain),
 						)
 					}),
+
+					c.deriveDivergencePointVerified(forkingPoint),
 				)
 			}),
 		),
@@ -270,15 +270,6 @@ func (c *Chain) deriveShouldEvict(forkingPoint *Commitment, parentChain *Chain)
 	return
 }
 
-// deriveIsSolid defines how a chain determines whether it is solid (has a connection to the root).
-func (c *Chain) deriveIsSolid(forkingPoint *Commitment, parentChain *Chain) (shutdown func()) {
-	if parentChain != nil {
-		return c.IsSolid.InheritFrom(parentChain.IsSolid)
-	}
-
-	return c.IsSolid.InheritFrom(forkingPoint.IsRoot)
-}
-
 // deriveWarpSyncMode defines how a chain determines whether it is in warp sync mode or not.
 func (c *Chain) deriveWarpSyncMode(engine *engine.Engine) func() {
 	return c.WarpSyncMode.DeriveValueFrom(reactive.NewDerivedVariable4(func(warpSyncMode bool, engineInitialized bool, latestSyncedSlot iotago.SlotIndex, latestSeenSlot iotago.SlotIndex, outOfSyncThreshold iotago.SlotIndex) bool {
@@ -305,6 +296,17 @@ func (c *Chain) deriveChildChains(child *Chain) (teardown func()) {
 	return
 }
 
+// deriveDivergencePointVerified defines how a chain determines whether its divergence point is verified.
+func (c *Chain) deriveDivergencePointVerified(forkingPoint *Commitment) (shutdown func()) {
+	return lo.Batch(
+		c.DivergencePointVerified.InheritFrom(forkingPoint.IsRoot),
+
+		forkingPoint.Parent.WithNonEmptyValue(func(parentOfForkingPoint *Commitment) (teardown func()) {
+			return c.DivergencePointVerified.InheritFrom(parentOfForkingPoint.IsVerified)
+		}),
+	)
+}
+
 // deriveParentChain defines how a chain determines its parent chain from its forking point (it inherits the Chain from
 // the parent commitment of the forking point or nil if either of them is still unknown).
 func (c *Chain) deriveParentChain(forkingPoint *Commitment) (shutdown func()) {
diff --git a/pkg/protocol/chains.go b/pkg/protocol/chains.go
index a874c5d76..01ce3d449 100644
--- a/pkg/protocol/chains.go
+++ b/pkg/protocol/chains.go
@@ -323,13 +323,7 @@ func (c *Chains) initChainSwitching() (shutdown func()) {
 
 	return lo.BatchReverse(
 		c.HeaviestClaimedCandidate.WithNonEmptyValue(func(heaviestClaimedCandidate *Chain) (shutdown func()) {
-			return heaviestClaimedCandidate.ForkingPoint.WithNonEmptyValue(func(forkingPoint *Commitment) (teardown func()) {
-				return forkingPoint.Parent.WithNonEmptyValue(func(parentOfForkingPoint *Commitment) (teardown func()) {
-					return parentOfForkingPoint.IsVerified.WithNonEmptyValue(func(_ bool) (teardown func()) {
-						return heaviestClaimedCandidate.RequestAttestations.ToggleValue(true)
-					})
-				})
-			})
+			return heaviestClaimedCandidate.RequestAttestations.ToggleValue(true)
 		}),
 
 		c.HeaviestAttestedCandidate.OnUpdate(func(_ *Chain, heaviestAttestedCandidate *Chain) {
@@ -351,7 +345,7 @@ func (c *Chains) initChainSwitching() (shutdown func()) {
 
 func (c *Chains) trackHeaviestCandidates(chain *Chain) (teardown func()) {
 	return chain.LatestCommitment.OnUpdate(func(_ *Commitment, latestCommitment *Commitment) {
-		chain.IsSolid.OnTrigger(func() {
+		chain.DivergencePointVerified.OnTrigger(func() {
 			targetSlot := latestCommitment.ID().Index()
 
 			if evictionEvent := c.protocol.EvictionEvent(targetSlot); !evictionEvent.WasTriggered() {