From 22c75605ee3c014fd5399ccfcde980cfff3242de Mon Sep 17 00:00:00 2001
From: Jack Robison <jackrobison@lbry.io>
Date: Thu, 22 Jul 2021 16:09:18 -0400
Subject: [PATCH] fix getting block hash during reorg

---
 lbry/wallet/server/block_processor.py | 8 ++------
 lbry/wallet/server/leveldb.py         | 8 ++++----
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/lbry/wallet/server/block_processor.py b/lbry/wallet/server/block_processor.py
index 5801ddb1e..336b1972d 100644
--- a/lbry/wallet/server/block_processor.py
+++ b/lbry/wallet/server/block_processor.py
@@ -201,7 +201,6 @@ class BlockProcessor:
         self.touched = set()
 
         # Caches of unflushed items.
-        self.block_hashes = []
         self.block_txs = []
         self.undo_infos = []
 
@@ -336,7 +335,7 @@ class BlockProcessor:
             for height, block_hash in zip(
                     reversed(range(min_start_height, min_start_height + self.coin.REORG_LIMIT)),
                     reversed(block_hashes_from_lbrycrd)):
-                if self.block_hashes[height][::-1].hex() == block_hash:
+                if self.db.get_block_hash(height)[::-1].hex() == block_hash:
                     break
                 count += 1
             self.logger.warning(f"blockchain reorg detected at {self.height}, unwinding last {count} blocks")
@@ -373,8 +372,7 @@ class BlockProcessor:
     def flush_data(self):
         """The data for a flush.  The lock must be taken."""
         assert self.state_lock.locked()
-        return FlushData(self.height, self.tx_count, self.block_hashes,
-                         self.block_txs, self.db_op_stack, self.tip)
+        return FlushData(self.height, self.tx_count, self.block_txs, self.db_op_stack, self.tip)
 
     async def flush(self):
         def flush():
@@ -1137,7 +1135,6 @@ class BlockProcessor:
         txs: List[Tuple[Tx, bytes]] = block.transactions
         block_hash = self.coin.header_hash(block.header)
 
-        self.block_hashes.append(block_hash)
         self.db_op_stack.append(RevertablePut(*Prefixes.block_hash.pack_item(height, block_hash)))
 
         tx_count = self.tx_count
@@ -1298,7 +1295,6 @@ class BlockProcessor:
         self.removed_claims_to_send_es.update(touched_and_deleted.deleted_claims)
 
         self.db.headers.pop()
-        self.block_hashes.pop()
         self.db.tx_counts.pop()
         self.tip = self.coin.header_hash(self.db.headers[-1])
         while len(self.db.total_transactions) > self.db.tx_counts[-1]:
diff --git a/lbry/wallet/server/leveldb.py b/lbry/wallet/server/leveldb.py
index 1c02208fb..49ed95a1d 100644
--- a/lbry/wallet/server/leveldb.py
+++ b/lbry/wallet/server/leveldb.py
@@ -65,7 +65,6 @@ TXO_STRUCT_pack = TXO_STRUCT.pack
 class FlushData:
     height = attr.ib()
     tx_count = attr.ib()
-    block_hashes = attr.ib()
     block_txs = attr.ib()
     put_and_delete_ops = attr.ib()
     tip = attr.ib()
@@ -382,8 +381,11 @@ class LevelDB:
 
     def get_claim_txo_amount(self, claim_hash: bytes) -> Optional[int]:
         v = self.db.get(Prefixes.claim_to_txo.pack_key(claim_hash))
+
+    def get_block_hash(self, height: int) -> Optional[bytes]:
+        v = self.db.get(Prefixes.block_hash.pack_key(height))
         if v:
-            return Prefixes.claim_to_txo.unpack_value(v).amount
+            return Prefixes.block_hash.unpack_value(v).block_hash
 
     def get_support_txo_amount(self, claim_hash: bytes, tx_num: int, position: int) -> Optional[int]:
         v = self.db.get(Prefixes.claim_to_support.pack_key(claim_hash, tx_num, position))
@@ -790,7 +792,6 @@ class LevelDB:
         assert flush_data.tx_count == self.fs_tx_count == self.db_tx_count
         assert flush_data.height == self.fs_height == self.db_height
         assert flush_data.tip == self.db_tip
-        assert not flush_data.block_txs
         assert not len(flush_data.put_and_delete_ops)
 
     def flush_dbs(self, flush_data: FlushData):
@@ -840,7 +841,6 @@ class LevelDB:
             self.write_db_state(batch)
 
     def flush_backup(self, flush_data):
-        assert not flush_data.block_txs
         assert flush_data.height < self.db_height
         assert not self.hist_unflushed