From 0315a31dd285ff971c40786eb536f0dc35bb92e6 Mon Sep 17 00:00:00 2001
From: Ian Norden <iannordenn@gmail.com>
Date: Sat, 27 Feb 2021 12:39:16 -0600
Subject: [PATCH] add endpoints for fetching/writing statediff by blockhash

---
 pkg/service.go | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/pkg/service.go b/pkg/service.go
index bd6eace..db787cf 100644
--- a/pkg/service.go
+++ b/pkg/service.go
@@ -55,10 +55,14 @@ type IService interface {
 	Loop(wg *sync.WaitGroup)
 	// Method to get state diff object at specific block
 	StateDiffAt(blockNumber uint64, params sd.Params) (*sd.Payload, error)
+	// Method to get state diff object at specific block
+	StateDiffFor(blockHash common.Hash, params sd.Params) (*sd.Payload, error)
 	// Method to get state trie object at specific block
 	StateTrieAt(blockNumber uint64, params sd.Params) (*sd.Payload, error)
 	// Method to write state diff object directly to DB
 	WriteStateDiffAt(blockNumber uint64, params sd.Params) error
+	// Method to get state trie object at specific block
+	WriteStateDiffFor(blockHash common.Hash, params sd.Params) error
 }
 
 // Service is the underlying struct for the state diffing service
@@ -135,6 +139,24 @@ func (sds *Service) StateDiffAt(blockNumber uint64, params sd.Params) (*sd.Paylo
 	return sds.processStateDiff(currentBlock, parentBlock.Root(), params)
 }
 
+// StateDiffFor returns a state diff object payload for the specific blockhash
+// This operation cannot be performed back past the point of db pruning; it requires an archival node for historical data
+func (sds *Service) StateDiffFor(blockHash common.Hash, params sd.Params) (*sd.Payload, error) {
+	currentBlock, err := sds.lvlDBReader.GetBlockByHash(blockHash)
+	if err != nil {
+		return nil, err
+	}
+	logrus.Info(fmt.Sprintf("sending state diff at block %s", blockHash.Hex()))
+	if currentBlock.NumberU64() == 0 {
+		return sds.processStateDiff(currentBlock, common.Hash{}, params)
+	}
+	parentBlock, err := sds.lvlDBReader.GetBlockByHash(currentBlock.ParentHash())
+	if err != nil {
+		return nil, err
+	}
+	return sds.processStateDiff(currentBlock, parentBlock.Root(), params)
+}
+
 // processStateDiff method builds the state diff payload from the current block, parent state root, and provided params
 func (sds *Service) processStateDiff(currentBlock *types.Block, parentRoot common.Hash, params sd.Params) (*sd.Payload, error) {
 	stateDiff, err := sds.Builder.BuildStateDiffObject(sd.Args{
@@ -244,6 +266,26 @@ func (sds *Service) WriteStateDiffAt(blockNumber uint64, params sd.Params) error
 	return sds.writeStateDiff(currentBlock, parentRoot, params)
 }
 
+// WriteStateDiffFor writes a state diff for the specific blockHash directly to the database
+// This operation cannot be performed back past the point of db pruning; it requires an archival node
+// for historical data
+func (sds *Service) WriteStateDiffFor(blockHash common.Hash, params sd.Params) error {
+	logrus.Info(fmt.Sprintf("Writing state diff for block %s", blockHash.Hex()))
+	currentBlock, err := sds.lvlDBReader.GetBlockByHash(blockHash)
+	if err != nil {
+		return err
+	}
+	parentRoot := common.Hash{}
+	if currentBlock.NumberU64() != 0 {
+		parentBlock, err := sds.lvlDBReader.GetBlockByHash(currentBlock.ParentHash())
+		if err != nil {
+			return err
+		}
+		parentRoot = parentBlock.Root()
+	}
+	return sds.writeStateDiff(currentBlock, parentRoot, params)
+}
+
 // Writes a state diff from the current block, parent state root, and provided params
 func (sds *Service) writeStateDiff(block *types.Block, parentRoot common.Hash, params sd.Params) error {
 	var totalDifficulty *big.Int