From b897505f8584c0dae8e18b9a2315c379ab990ebe Mon Sep 17 00:00:00 2001
From: Alexander Block <ablock84@gmail.com>
Date: Fri, 5 Apr 2019 06:59:50 +0200
Subject: [PATCH] Remove the need for maintaining the last ChainLocked block in
 the DB

---
 src/llmq/quorums_instantsend.cpp | 34 ++++++--------------------------
 src/llmq/quorums_instantsend.h   |  3 ---
 2 files changed, 6 insertions(+), 31 deletions(-)

diff --git a/src/llmq/quorums_instantsend.cpp b/src/llmq/quorums_instantsend.cpp
index 172055e2248fc..7f9b054958778 100644
--- a/src/llmq/quorums_instantsend.cpp
+++ b/src/llmq/quorums_instantsend.cpp
@@ -201,18 +201,6 @@ CInstantSendLockPtr CInstantSendDb::GetInstantSendLockByInput(const COutPoint& o
     return GetInstantSendLockByHash(islockHash);
 }
 
-void CInstantSendDb::WriteLastChainLockBlock(const uint256& hash)
-{
-    db.Write(std::make_tuple(std::string("is_lcb")), hash);
-}
-
-uint256 CInstantSendDb::GetLastChainLockBlock()
-{
-    uint256 hashBlock;
-    db.Read(std::make_tuple(std::string("is_lcb")), hashBlock);
-    return hashBlock;
-}
-
 ////////////////
 
 CInstantSendManager::CInstantSendManager(CScheduler* _scheduler, CDBWrapper& _llmqDb) :
@@ -820,11 +808,6 @@ void CInstantSendManager::SyncTransaction(const CTransaction& tx, const CBlockIn
 
 void CInstantSendManager::NotifyChainLock(const CBlockIndex* pindexChainLock)
 {
-    {
-        LOCK(cs);
-        db.WriteLastChainLockBlock(pindexChainLock->GetBlockHash());
-    }
-
     HandleFullyConfirmedBlock(pindexChainLock);
 }
 
@@ -913,26 +896,21 @@ void CInstantSendManager::RetryLockTxs(const uint256& lockedParentTx)
         }
     }
 
-    uint256 lastChainLockBlock;
-    const CBlockIndex* pindexLastChainLockBlock = nullptr;
     const CBlockIndex* pindexWalk = nullptr;
-    {
-        LOCK(cs);
-        lastChainLockBlock = db.GetLastChainLockBlock();
-    }
     {
         LOCK(cs_main);
-        if (!lastChainLockBlock.IsNull()) {
-            pindexLastChainLockBlock = mapBlockIndex.at(lastChainLockBlock);
-            pindexWalk = chainActive.Tip();
-        }
+        pindexWalk = chainActive.Tip();
     }
 
     // scan blocks until we hit the last chainlocked block we know of. Also stop scanning after a depth of 6 to avoid
     // signing thousands of TXs at once. Also, after a depth of 6, blocks get eligible for ChainLocking even if unsafe
     // TXs are included, so there is no need to retroactively sign these.
     int depth = 0;
-    while (pindexWalk && pindexWalk != pindexLastChainLockBlock && depth < 6) {
+    while (pindexWalk && depth < 6) {
+        if (chainLocksHandler->HasChainLock(pindexWalk->nHeight, pindexWalk->GetBlockHash())) {
+            break;
+        }
+
         CBlock block;
         {
             LOCK(cs_main);
diff --git a/src/llmq/quorums_instantsend.h b/src/llmq/quorums_instantsend.h
index b4c2d009c1e4d..2355b984a9ebe 100644
--- a/src/llmq/quorums_instantsend.h
+++ b/src/llmq/quorums_instantsend.h
@@ -66,9 +66,6 @@ class CInstantSendDb
     uint256 GetInstantSendLockHashByTxid(const uint256& txid);
     CInstantSendLockPtr GetInstantSendLockByTxid(const uint256& txid);
     CInstantSendLockPtr GetInstantSendLockByInput(const COutPoint& outpoint);
-
-    void WriteLastChainLockBlock(const uint256& hashBlock);
-    uint256 GetLastChainLockBlock();
 };
 
 class CInstantSendManager : public CRecoveredSigsListener