sharding: collation header hash and shard receiver methods

Former-commit-id: 4cbacc539c2ef7c273c926d989449def39bf7b9a [formerly 7930332c151ad370317590556169411f875c84f9]
Former-commit-id: 7533fcba8e6c6739ccb8ade408654e2b18e50c83

sharding/collation.go

@@ -4,6 +4,8 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/rlp"
 )
 
 type Collation struct {
@@ -19,6 +21,14 @@ type CollationHeader struct {
 	proposerSignature []byte          //the proposer's signature for calculating collation hash
 }
 
+// Hash takes the keccak256 of the collation header's contents.
+func (h *CollationHeader) Hash() (hash common.Hash) {
+	hw := sha3.NewKeccak256()
+	rlp.Encode(hw, h)
+	hw.Sum(hash[:0])
+	return hash
+}
+
 func (c *Collation) Header() *CollationHeader         { return c.header }
 func (c *Collation) ShardID() *big.Int                { return c.header.shardID }
 func (c *Collation) Period() *big.Int                 { return c.header.period }

sharding/db.go

@@ -1,21 +1,29 @@
 package sharding
 
-import "github.com/ethereum/go-ethereum/common"
+import (
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/common"
+)
 
 type shardBackend struct {
-	kv map[*common.Hash][]byte
+	kv map[common.Hash][]byte
 }
 
-func (sb *shardBackend) Get(k *common.Hash) []byte {
+func (sb *shardBackend) Get(k common.Hash) ([]byte, error) {
-	return sb.kv[k]
+	v := sb.kv[k]
+	if v == nil {
+		return nil, fmt.Errorf("Key Not Found")
+	}
+	return v, nil
 }
 
-func (sb *shardBackend) Put(k *common.Hash, v []byte) {
+func (sb *shardBackend) Put(k common.Hash, v []byte) {
 	sb.kv[k] = v
 	return
 }
 
-func (sb *shardBackend) Delete(k *common.Hash) {
+func (sb *shardBackend) Delete(k common.Hash) {
 	delete(sb.kv, k)
 	return
 }

sharding/shard.go

@@ -22,28 +22,39 @@ func (s *Shard) ValidateShardID(h *CollationHeader) error {
 	return nil
 }
 
+// SetHeader adds the collation header to shardDB
+func (s *Shard) SetHeader(h *CollationHeader) error {
+	if err := s.ValidateShardID(h); err != nil {
+		return err
+	}
+	encoded, err := rlp.EncodeToBytes(h)
+	if err != nil {
+		return fmt.Errorf("Error: Cannot Encode Header")
+	}
+	s.shardDB.Put(h.Hash(), encoded)
+	return nil
+}
+
 // GetHeaderByHash of collation.
-func (s *Shard) GetHeaderByHash(hash *common.Hash) (*CollationHeader, error) {
+func (s *Shard) GetHeaderByHash(hash common.Hash) (*CollationHeader, error) {
-	encoded := s.shardDB.Get(hash)
+	encoded, err := s.shardDB.Get(hash)
+	if err != nil {
+		return nil, fmt.Errorf("Error: Header Not Found")
+	}
 	var header CollationHeader
 	if err := rlp.DecodeBytes(encoded, &header); err != nil {
-		return nil, fmt.Errorf("Error Decoding Header: %v", err)
+		return nil, fmt.Errorf("Error: Problem Decoding Header: %v", err)
 	}
 	return &header, nil
 }
 
-// GetHeaderByPeriod the header was added.
-func (s *Shard) GetHeaderByPeriod(period *big.Int) *CollationHeader {
-	return nil
-}
-
 // GetCollationByHash fetches full collation.
-func (s *Shard) GetCollationByHash(hash *common.Hash) (*Collation, error) {
+func (s *Shard) GetCollationByHash(hash common.Hash) (*Collation, error) {
 	header, err := s.GetHeaderByHash(hash)
 	if err != nil {
 		return nil, err
 	}
-	body, err := s.GetBodyByChunkRoot(header.chunkRoot)
+	body, err := s.GetBodyByChunkRoot(*header.chunkRoot)
 	if err != nil {
 		return nil, err
 	}
@@ -51,9 +62,9 @@ func (s *Shard) GetCollationByHash(hash *common.Hash) (*Collation, error) {
 }
 
 // GetBodyByChunkRoot fetches a collation body
-func (s *Shard) GetBodyByChunkRoot(chunkRoot *common.Hash) ([]byte, error) {
+func (s *Shard) GetBodyByChunkRoot(chunkRoot common.Hash) ([]byte, error) {
-	body := s.shardDB.Get(chunkRoot)
+	body, err := s.shardDB.Get(chunkRoot)
-	if body == nil {
+	if err != nil {
 		return nil, fmt.Errorf("Error: No Corresponding Body With Chunk Root Found")
 	}
 	return body, nil
@@ -68,11 +79,3 @@ func (s *Shard) CheckAvailability(header *CollationHeader) bool {
 func (s *Shard) SetUnavailable(header *CollationHeader) error {
 	return nil
 }
-
-// SetCanonical is called after >= 2/3 notaries vote on header and period ends.
-func (s *Shard) SetCanonical(header *CollationHeader) error {
-	return nil
-}
-
-// Set Header and Set Body Methods
-// TODO: error in Get from the kv store