From 816aac82d5155ad7d644f424a2d5ce6f23105dd7 Mon Sep 17 00:00:00 2001
From: Raul Jordan <raul@prysmaticlabs.com>
Date: Wed, 28 Aug 2019 15:14:00 -0500
Subject: [PATCH] clone read access to head state and block (#3350)

---
 beacon-chain/blockchain/BUILD.bazel   | 1 +
 beacon-chain/blockchain/chain_info.go | 5 +++--
 beacon-chain/blockchain/service.go    | 1 -
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/beacon-chain/blockchain/BUILD.bazel b/beacon-chain/blockchain/BUILD.bazel
index f61c5ff22..bcac77f55 100644
--- a/beacon-chain/blockchain/BUILD.bazel
+++ b/beacon-chain/blockchain/BUILD.bazel
@@ -27,6 +27,7 @@ go_library(
         "//proto/eth/v1alpha1:go_default_library",
         "//shared/bytesutil:go_default_library",
         "//shared/event:go_default_library",
+        "@com_github_gogo_protobuf//proto:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
         "@com_github_prometheus_client_golang//prometheus:go_default_library",
         "@com_github_prometheus_client_golang//prometheus/promauto:go_default_library",
diff --git a/beacon-chain/blockchain/chain_info.go b/beacon-chain/blockchain/chain_info.go
index 4ba78690d..90ba04417 100644
--- a/beacon-chain/blockchain/chain_info.go
+++ b/beacon-chain/blockchain/chain_info.go
@@ -3,6 +3,7 @@ package blockchain
 import (
 	"time"
 
+	"github.com/gogo/protobuf/proto"
 	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
 	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
 )
@@ -57,12 +58,12 @@ func (c *ChainService) HeadRoot() []byte {
 
 // HeadBlock returns the head block of the chain.
 func (c *ChainService) HeadBlock() *ethpb.BeaconBlock {
-	return c.headBlock
+	return proto.Clone(c.headBlock).(*ethpb.BeaconBlock)
 }
 
 // HeadState returns the head state of the chain.
 func (c *ChainService) HeadState() *pb.BeaconState {
-	return c.headState
+	return proto.Clone(c.headState).(*pb.BeaconState)
 }
 
 // CanonicalRoot returns the canonical root of a given slot.
diff --git a/beacon-chain/blockchain/service.go b/beacon-chain/blockchain/service.go
index 860402f57..b9419e064 100644
--- a/beacon-chain/blockchain/service.go
+++ b/beacon-chain/blockchain/service.go
@@ -212,7 +212,6 @@ func (c *ChainService) saveHead(ctx context.Context, b *ethpb.BeaconBlock, r [32
 		"slots": b.Slot,
 		"root":  hex.EncodeToString(r[:]),
 	}).Debug("Saved head info")
-
 	return nil
 }