Refactor CrossLink RPC (#2512)

* [README] Update required go version in README to 1.13.6

* [rpc] Refactor GetLastCrossLinks RPC

README.md

@@ -112,7 +112,7 @@ based library dependencies (`libbls` and `mcl`) setup correctly for you. You can
 versions easily, an example:
 
 ```
-$ eval $(gimme 1.12.6)
+$ eval $(gimme 1.13.6)
 ```
 
 Note that changing the go version might mean that dependencies won't work out right when trying to
@@ -129,7 +129,7 @@ brew install openssl
 
 ## Dev Environment Setup
 
-The required go version is: **go1.12**
+The required go version is: **go1.13.6**
 
 ```bash
 export GOPATH=$HOME/<path_of_your_choice>

core/types/crosslink.go

@@ -2,6 +2,7 @@ package types
 
 import (
 	"encoding/hex"
+	"encoding/json"
 	"math/big"
 	"sort"
 
@@ -24,16 +25,6 @@ type CrossLink struct {
 	EpochF       *big.Int
 }
 
-// RPCCrossLink is used for returning data to RPC calls, converting byte arrays to hex encoded strings
-type RPCCrossLink struct {
-	HashF        common.Hash `json:"parentHash"`
-	BlockNumberF *big.Int    `json:"blockNumber"`
-	SignatureF   string      `json:"signature"`
-	BitmapF      string      `json:"signatureBitmap"`
-	ShardIDF     uint32      `json:"shardId"`
-	EpochF       *big.Int    `json:"epochNumber"`
-}
-
 // NewCrossLink returns a new cross link object
 // epoch is the parentHeader's epoch
 func NewCrossLink(header *block.Header, epoch *big.Int) CrossLink {
@@ -80,16 +71,23 @@ func (cl CrossLink) Signature() [96]byte {
 	return cl.SignatureF
 }
 
-// ConvertForRPC converts CrossLink into RPCCrossLink
-func (cl CrossLink) ConvertForRPC() *RPCCrossLink {
-	return &RPCCrossLink{
-		HashF:        cl.HashF,
-		BlockNumberF: cl.BlockNumberF,
-		SignatureF:   hex.EncodeToString(cl.SignatureF[:]),
-		BitmapF:      hex.EncodeToString(cl.BitmapF),
-		ShardIDF:     cl.ShardIDF,
-		EpochF:       cl.EpochF,
-	}
+// MarshalJSON ..
+func (cl CrossLink) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Hash        common.Hash `json:"hash"`
+		BlockNumber *big.Int    `json:"block-number"`
+		Signature   string      `json:"signature"`
+		Bitmap      string      `json:"signature-bitmap"`
+		ShardID     uint32      `json:"shard-id"`
+		EpochNumber *big.Int    `json:"epoch-number"`
+	}{
+		cl.HashF,
+		cl.BlockNumberF,
+		hex.EncodeToString(cl.SignatureF[:]),
+		hex.EncodeToString(cl.BitmapF),
+		cl.ShardIDF,
+		cl.EpochF,
+	})
 }
 
 // Serialize returns bytes of cross link rlp-encoded content

hmy/api_backend.go

@@ -581,15 +581,15 @@ func (b *APIBackend) GetCurrentBadBlocks() []core.BadBlock {
 }
 
 // GetLastCrossLinks ..
-func (b *APIBackend) GetLastCrossLinks() ([]*types.RPCCrossLink, error) {
-	lastCrossLinks := []*types.RPCCrossLink{}
+func (b *APIBackend) GetLastCrossLinks() ([]*types.CrossLink, error) {
+	crossLinks := []*types.CrossLink{}
 	for i := uint32(1); i < shard.Schedule.InstanceForEpoch(b.CurrentBlock().Epoch()).NumShards(); i++ {
 		link, err := b.hmy.BlockChain().ReadShardLastCrossLink(i)
 		if err != nil {
 			return nil, err
 		}
-		lastCrossLinks = append(lastCrossLinks, link.ConvertForRPC())
+		crossLinks = append(crossLinks, link)
 	}
 
-	return lastCrossLinks, nil
+	return crossLinks, nil
 }

internal/hmyapi/apiv1/backend.go

@@ -87,5 +87,5 @@ type Backend interface {
 	GetSuperCommittees() (*quorum.Transition, error)
 	GetTotalStakingSnapshot() *big.Int
 	GetCurrentBadBlocks() []core.BadBlock
-	GetLastCrossLinks() ([]*types.RPCCrossLink, error)
+	GetLastCrossLinks() ([]*types.CrossLink, error)
 }

internal/hmyapi/apiv1/blockchain.go

@@ -848,6 +848,9 @@ func (s *PublicBlockChainAPI) GetStakingNetworkInfo(ctx context.Context) (*Staki
 }
 
 // GetLastCrossLinks ..
-func (s *PublicBlockChainAPI) GetLastCrossLinks() ([]*types.RPCCrossLink, error) {
-	return s.b.GetLastCrossLinks()
+func (s *PublicBlockChainAPI) GetLastCrossLinks() ([]*types.CrossLink, error) {
+	if s.b.GetShardID() == shard.BeaconChainShardID {
+		return s.b.GetLastCrossLinks()
+	}
+	return nil, errNotBeaconChainShard
 }

internal/hmyapi/apiv2/backend.go

@@ -87,5 +87,5 @@ type Backend interface {
 	GetSuperCommittees() (*quorum.Transition, error)
 	GetTotalStakingSnapshot() *big.Int
 	GetCurrentBadBlocks() []core.BadBlock
-	GetLastCrossLinks() ([]*types.RPCCrossLink, error)
+	GetLastCrossLinks() ([]*types.CrossLink, error)
 }

internal/hmyapi/apiv2/blockchain.go

@@ -813,6 +813,9 @@ func (s *PublicBlockChainAPI) GetStakingNetworkInfo(ctx context.Context) (*Staki
 }
 
 // GetLastCrossLinks ..
-func (s *PublicBlockChainAPI) GetLastCrossLinks() ([]*types.RPCCrossLink, error) {
-	return s.b.GetLastCrossLinks()
+func (s *PublicBlockChainAPI) GetLastCrossLinks() ([]*types.CrossLink, error) {
+	if s.b.GetShardID() == shard.BeaconChainShardID {
+		return s.b.GetLastCrossLinks()
+	}
+	return nil, errNotBeaconChainShard
 }

internal/hmyapi/backend.go

@@ -89,7 +89,7 @@ type Backend interface {
 	GetSuperCommittees() (*quorum.Transition, error)
 	GetTotalStakingSnapshot() *big.Int
 	GetCurrentBadBlocks() []core.BadBlock
-	GetLastCrossLinks() ([]*types.RPCCrossLink, error)
+	GetLastCrossLinks() ([]*types.CrossLink, error)
 }
 
 // GetAPIs returns all the APIs.