feat: implementing answerProspectiveValidationDataRequest

dot/parachain/prospective-parachains/fragment_chain.go

@@ -617,7 +617,7 @@ func (f *fragmentChain) tryAddingSecondedCandidate(entry *candidateEntry) error
 }
 
 // getHeadDataByHash tries to get the full head data associated with this hash
-func (f *fragmentChain) getHeadDataByHash(headDataHash common.Hash) (*parachaintypes.HeadData, error) { //nolint:unused
+func (f *fragmentChain) getHeadDataByHash(headDataHash common.Hash) (*parachaintypes.HeadData, error) {
 	reqParent := f.scope.baseConstraints.RequiredParent
 	reqParentHash, err := reqParent.Hash()
 	if err != nil {

dot/parachain/prospective-parachains/messages.go

@@ -133,7 +133,7 @@ func (GetMinimumRelayParents) isProspectiveParachainsMessage() {}
 // some fragment chain).
 type GetProspectiveValidationData struct {
 	ProspectiveValidationDataRequest
-	Sender chan parachaintypes.PersistedValidationData
+	Sender chan<- *parachaintypes.PersistedValidationData
 }
 
 // ProspectiveValidationDataRequest A request for the persisted validation data stored in the prospective
@@ -153,15 +153,15 @@ type ParentHeadData interface {
 }
 
 // ParentHeadDataHash Parent head-data hash.
-type ParentHeadDataHash common.Hash
+type OnlyHash common.Hash
 
-func (ParentHeadDataHash) isParentHeadData() {}
+func (OnlyHash) isParentHeadData() {}
 
 type ParentHeadDataWithHash struct {
 	// This will be provided for collations with elastic scaling enabled.
 	Data parachaintypes.HeadData
 	// Parent head-data hash.
-	Hash ParentHeadDataHash
+	Hash common.Hash
 }
 
 func (ParentHeadDataWithHash) isParentHeadData() {}

dot/parachain/prospective-parachains/prospective-parachains.go

@@ -93,7 +93,7 @@ func (pp *ProspectiveParachains) processMessage(msg any) {
 		// Directly use the msg since it's already of type GetMinimumRelayParents
 		pp.getMinimumRelayParents(msg.RelayChainBlockHash, msg.Sender)
 	case GetProspectiveValidationData:
-		panic("not implemented yet: see issue #4313")
+		pp.answerProspectiveValidationDataRequest(msg.ProspectiveValidationDataRequest, msg.Sender)
 	default:
 		logger.Errorf("%w: %T", parachaintypes.ErrUnknownOverseerMessage, msg)
 	}
@@ -298,3 +298,75 @@ func (pp *ProspectiveParachains) getBackableCandidates(
 	// Send the result through the response channel
 	responseChan <- candidateHashes
 }
+
+func (pp *ProspectiveParachains) answerProspectiveValidationDataRequest(
+	request ProspectiveValidationDataRequest,
+	response chan<- *parachaintypes.PersistedValidationData,
+) {
+	var headData *parachaintypes.HeadData
+	var parentHeadDataHash common.Hash
+
+	// extracting informations from the request depending on the incoming type.
+	switch value := request.ParentHeadData.(type) {
+	case OnlyHash:
+		parentHeadDataHash = common.Hash(value)
+	case ParentHeadDataWithHash:
+		headData = &value.Data
+		parentHeadDataHash = value.Hash
+	}
+
+	var relayParentInfo *relayChainBlockInfo
+	var maxPovSize *uint32
+
+	// // iterate over active leaves
+	for leaf := range pp.View.activeLeaves {
+		relayBlockViewData, exists := pp.View.perRelayParent[leaf]
+
+		if !exists {
+			continue
+		}
+
+		fragmentChain, exists := relayBlockViewData.fragmentChains[request.ParaId]
+		if !exists {
+			continue
+		}
+
+		// stop the iteration once we retrieve all the informations
+		if headData != nil && relayParentInfo != nil && maxPovSize != nil {
+			break
+		}
+
+		if relayParentInfo == nil {
+			relayParentInfo = fragmentChain.scope.ancestor(request.CandidateRelayParent)
+		}
+
+		if headData == nil {
+			var err error
+			headData, err = fragmentChain.getHeadDataByHash(parentHeadDataHash)
+
+			if err != nil {
+				response <- nil
+				return
+			}
+		}
+
+		if maxPovSize == nil {
+			containAncestor := fragmentChain.scope.ancestor(request.CandidateRelayParent) != nil
+
+			if containAncestor {
+				maxPovSize = &fragmentChain.scope.baseConstraints.MaxPoVSize
+			}
+		}
+	}
+
+	if headData != nil && relayParentInfo != nil && maxPovSize != nil {
+		response <- &parachaintypes.PersistedValidationData{
+			ParentHead:             *headData,
+			RelayParentNumber:      uint32(relayParentInfo.Number),
+			RelayParentStorageRoot: relayParentInfo.StorageRoot,
+			MaxPovSize:             *maxPovSize,
+		}
+	} else {
+		response <- nil
+	}
+}

dot/parachain/prospective-parachains/prospective_parachains_test.go

@@ -654,3 +654,248 @@ func TestGetBackableCandidates(t *testing.T) {
 		})
 	}
 }
+
+func TestAnswerProspectiveValidationDataRequest(t *testing.T) {
+	// Create a new prospective parachains instance
+	subsystemToOverseer := make(chan any)
+
+	t.Run("no_active_leaves", func(t *testing.T) {
+		view := &view{
+			activeLeaves: map[common.Hash]bool{},
+		}
+
+		// Create a prospective validation data request
+		request := ProspectiveValidationDataRequest{
+			ParaId:               parachaintypes.ParaID(1),
+			CandidateRelayParent: common.Hash{0x01},
+			ParentHeadData: ParentHeadDataWithHash{
+				Hash: common.Hash{0x01},
+				Data: parachaintypes.HeadData{Data: []byte{0x01}},
+			},
+		}
+
+		pp := &ProspectiveParachains{
+			View: view,
+		}
+
+		sender := make(chan *parachaintypes.PersistedValidationData, 1)
+
+		// Execute the method under test
+		pp.answerProspectiveValidationDataRequest(request, sender)
+
+		result := <-sender
+
+		assert.Nil(t, result, "Expected result to be nil when no active leaves are present")
+	})
+
+	t.Run("with_active_and_only_hash", func(t *testing.T) {
+		reqParent := parachaintypes.HeadData{Data: []byte{0xc3}}
+		reqParentHash, err := reqParent.Hash()
+		assert.NoError(t, err)
+
+		baseConstraints := &parachaintypes.Constraints{
+			RequiredParent:       reqParent,
+			MinRelayParentNumber: 0,
+			ValidationCodeHash:   parachaintypes.ValidationCodeHash(common.Hash{0x03}),
+			MaxPoVSize:           3,
+		}
+
+		scope, err := newScopeWithAncestors(
+			relayChainBlockInfo{
+				Hash:        common.Hash{0x01},
+				StorageRoot: common.Hash{0x01},
+				Number:      2,
+			},
+			baseConstraints,
+			nil,
+			3,
+			[]relayChainBlockInfo{
+				{
+					Hash:        common.Hash{0x012},
+					StorageRoot: common.Hash{0x022},
+					Number:      1,
+				},
+			},
+		)
+
+		assert.NoError(t, err)
+
+		view := &view{
+			activeLeaves: map[common.Hash]bool{
+				{0x01}: true,
+			},
+			perRelayParent: map[common.Hash]*relayParentData{
+				{0x01}: {
+					fragmentChains: map[parachaintypes.ParaID]*fragmentChain{
+						parachaintypes.ParaID(1): newFragmentChain(scope, newCandidateStorage()),
+					},
+				},
+			},
+		}
+
+		// Create a prospective validation data request
+		request := ProspectiveValidationDataRequest{
+			ParaId:               parachaintypes.ParaID(1),
+			CandidateRelayParent: common.Hash{0x01},
+			ParentHeadData:       OnlyHash(reqParentHash),
+		}
+
+		pp := &ProspectiveParachains{
+			View: view,
+		}
+
+		sender := make(chan *parachaintypes.PersistedValidationData, 1)
+
+		// Execute the method under test
+		pp.answerProspectiveValidationDataRequest(request, sender)
+
+		result := <-sender
+
+		assert.Equal(t, result.ParentHead, reqParent)
+		assert.Equal(t, result.RelayParentNumber, uint32(2))
+		assert.Equal(t, result.RelayParentStorageRoot, common.Hash{0x01})
+		assert.Equal(t, result.MaxPovSize, uint32(3))
+	})
+
+	t.Run("with_active_and_with_head_data", func(t *testing.T) {
+		reqParent := parachaintypes.HeadData{Data: []byte{0xc3}}
+		reqParentHash, err := reqParent.Hash()
+		assert.NoError(t, err)
+
+		baseConstraints := &parachaintypes.Constraints{
+			RequiredParent:       reqParent,
+			MinRelayParentNumber: 0,
+			ValidationCodeHash:   parachaintypes.ValidationCodeHash(common.Hash{0x03}),
+			MaxPoVSize:           3,
+		}
+
+		scope, err := newScopeWithAncestors(
+			relayChainBlockInfo{
+				Hash:        common.Hash{0x01},
+				StorageRoot: common.Hash{0x01},
+				Number:      2,
+			},
+			baseConstraints,
+			nil,
+			3,
+			[]relayChainBlockInfo{
+				{
+					Hash:        common.Hash{0x012},
+					StorageRoot: common.Hash{0x022},
+					Number:      1,
+				},
+			},
+		)
+
+		assert.NoError(t, err)
+
+		view := &view{
+			activeLeaves: map[common.Hash]bool{
+				{0x01}: true,
+			},
+			perRelayParent: map[common.Hash]*relayParentData{
+				{0x01}: {
+					fragmentChains: map[parachaintypes.ParaID]*fragmentChain{
+						parachaintypes.ParaID(1): newFragmentChain(scope, newCandidateStorage()),
+					},
+				},
+			},
+		}
+
+		// Create a prospective validation data request
+		request := ProspectiveValidationDataRequest{
+			ParaId:               parachaintypes.ParaID(1),
+			CandidateRelayParent: common.Hash{0x01},
+			ParentHeadData: ParentHeadDataWithHash{
+				Data: reqParent,
+				Hash: reqParentHash,
+			},
+		}
+
+		pp := &ProspectiveParachains{
+			View: view,
+		}
+
+		sender := make(chan *parachaintypes.PersistedValidationData, 1)
+
+		// Execute the method under test
+		pp.answerProspectiveValidationDataRequest(request, sender)
+
+		result := <-sender
+
+		assert.Equal(t, result.ParentHead, reqParent)
+		assert.Equal(t, result.RelayParentNumber, uint32(2))
+		assert.Equal(t, result.RelayParentStorageRoot, common.Hash{0x01})
+		assert.Equal(t, result.MaxPovSize, uint32(3))
+	})
+
+	t.Run("with_head_data_hash_doesnt_match", func(t *testing.T) {
+		reqParent := parachaintypes.HeadData{Data: []byte{0xc4}}
+
+		baseConstraints := &parachaintypes.Constraints{
+			RequiredParent:       reqParent,
+			MinRelayParentNumber: 0,
+			ValidationCodeHash:   parachaintypes.ValidationCodeHash(common.Hash{0x03}),
+			MaxPoVSize:           3,
+		}
+
+		scope, err := newScopeWithAncestors(
+			relayChainBlockInfo{
+				Hash:        common.Hash{0x01},
+				StorageRoot: common.Hash{0x01},
+				Number:      2,
+			},
+			baseConstraints,
+			nil,
+			3,
+			[]relayChainBlockInfo{
+				{
+					Hash:        common.Hash{0x012},
+					StorageRoot: common.Hash{0x022},
+					Number:      1,
+				},
+			},
+		)
+
+		assert.NoError(t, err)
+
+		view := &view{
+			activeLeaves: map[common.Hash]bool{
+				{0x01}: true,
+			},
+			perRelayParent: map[common.Hash]*relayParentData{
+				{0x01}: {
+					fragmentChains: map[parachaintypes.ParaID]*fragmentChain{
+						parachaintypes.ParaID(1): newFragmentChain(scope, newCandidateStorage()),
+					},
+				},
+			},
+		}
+
+		// Create a prospective validation data request
+		request := ProspectiveValidationDataRequest{
+			ParaId:               parachaintypes.ParaID(1),
+			CandidateRelayParent: common.Hash{0x01},
+			ParentHeadData: ParentHeadDataWithHash{
+				Data: reqParent,
+				Hash: common.Hash{0xc3},
+			},
+		}
+
+		pp := &ProspectiveParachains{
+			View: view,
+		}
+
+		sender := make(chan *parachaintypes.PersistedValidationData, 1)
+
+		// Execute the method under test
+		pp.answerProspectiveValidationDataRequest(request, sender)
+
+		result := <-sender
+
+		assert.NotEqual(t, result.ParentHead, common.Hash{0xc3})
+	})
+
+	// Close the channels
+	close(subsystemToOverseer)
+}