From 3dd263a9b9cb6fbff8ce0b7e5347c572b019fe26 Mon Sep 17 00:00:00 2001
From: "James C. Owens" <jamesowens@optonline.net>
Date: Thu, 30 Nov 2023 14:07:50 -0500
Subject: [PATCH] Implement lock for GridcoinConnectBlock to queued txindex
 write.

---
 src/gridcoin/voting/result.cpp | 17 ++++++++++---
 src/main.cpp                   |  1 +
 src/main.h                     |  1 +
 src/validation.cpp             | 45 ++++++++++++++++++++--------------
 4 files changed, 43 insertions(+), 21 deletions(-)

diff --git a/src/gridcoin/voting/result.cpp b/src/gridcoin/voting/result.cpp
index ef523a2cd3..51047e546a 100644
--- a/src/gridcoin/voting/result.cpp
+++ b/src/gridcoin/voting/result.cpp
@@ -864,6 +864,7 @@ class VoteCounter
     {
         CTransaction tx;
 
+        /*
         bool read_tx_success = false;
 
         // This is very ugly. In testing for implement poll expiration reminders PR2716, there is an issue with ReadDiskTx
@@ -884,11 +885,21 @@ class VoteCounter
             }
         }
 
-        if (!read_tx_success) {
-            LogPrintf("WARN: %s: failed to read vote tx after 10 tries", __func__);
-            throw InvalidVoteError();
+         if (!read_tx_success) {
+             LogPrintf("WARN: %s: failed to read vote tx after 10 tries", __func__);
+             throw InvalidVoteError();
+         }
+         */
+
+        {
+            LOCK(cs_tx_val_commit_to_disk);
+
+            if (!m_txdb.ReadDiskTx(txid, tx)) {
+                LogPrintf("WARN: %s: failed to read vote tx.", __func__);
+            }
         }
 
+
         if (tx.nTime < m_poll.m_timestamp) {
             LogPrintf("WARN: %s: tx earlier than poll", __func__);
             throw InvalidVoteError();
diff --git a/src/main.cpp b/src/main.cpp
index 4fbe0e2740..137a345a12 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -62,6 +62,7 @@ CCriticalSection cs_setpwalletRegistered;
 set<CWallet*> setpwalletRegistered;
 
 CCriticalSection cs_main;
+CCriticalSection cs_tx_val_commit_to_disk;
 
 CTxMemPool mempool;
 
diff --git a/src/main.h b/src/main.h
index 336333f4a3..5af4e3e47a 100644
--- a/src/main.h
+++ b/src/main.h
@@ -75,6 +75,7 @@ typedef std::unordered_map<uint256, CBlockIndex*, BlockHasher> BlockMap;
 
 extern CScript COINBASE_FLAGS;
 extern CCriticalSection cs_main;
+extern CCriticalSection cs_tx_val_commit_to_disk;
 extern BlockMap mapBlockIndex;
 extern CBlockIndex* pindexGenesisBlock;
 extern unsigned int nStakeMinAge;
diff --git a/src/validation.cpp b/src/validation.cpp
index d9b12eb165..e397f59962 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1641,30 +1641,39 @@ bool ConnectBlock(CBlock& block, CTxDB& txdb, CBlockIndex* pindex, bool fJustChe
         mapQueuedChanges[hashTx] = CTxIndex(posThisTx, tx.vout.size());
     }
 
-    if (IsResearchAgeEnabled(pindex->nHeight)
-        && !GridcoinConnectBlock(block, pindex, txdb, stake_value_in, nStakeReward, nFees))
     {
-        return false;
-    }
+        // This lock protects the time period between the GridcoinConnectBlock, which also connects validated transaction contracts
+        // and causes contract handlers to fire, and the committing of the txindex changes to disk below. Any contract handlers that
+        // generate signals whose downstream handlers make use of transaction data on disk via leveldb (txdb) on another thread need
+        // to take this lock to ensure that the write to leveldb and the access of the transaction data by the signal handlers is
+        // appropriately serialized.
+        LOCK(cs_tx_val_commit_to_disk);
+
+        if (IsResearchAgeEnabled(pindex->nHeight)
+            && !GridcoinConnectBlock(block, pindex, txdb, stake_value_in, nStakeReward, nFees))
+        {
+            return false;
+        }
 
-    pindex->nMoneySupply = ReturnCurrentMoneySupply(pindex) + nValueOut - nValueIn;
+        pindex->nMoneySupply = ReturnCurrentMoneySupply(pindex) + nValueOut - nValueIn;
 
-    if (!txdb.WriteBlockIndex(CDiskBlockIndex(pindex)))
-        return error("%s: WriteBlockIndex for pindex failed", __func__);
+        if (!txdb.WriteBlockIndex(CDiskBlockIndex(pindex)))
+            return error("%s: WriteBlockIndex for pindex failed", __func__);
 
-    if (!OutOfSyncByAge())
-    {
-        fColdBoot = false;
-    }
+        if (!OutOfSyncByAge())
+        {
+            fColdBoot = false;
+        }
 
-    if (fJustCheck)
-        return true;
+        if (fJustCheck)
+            return true;
 
-    // Write queued txindex changes
-    for (const auto& [hash, index] : mapQueuedChanges)
-    {
-        if (!txdb.UpdateTxIndex(hash, index))
-            return error("%s: UpdateTxIndex failed", __func__);
+        // Write queued txindex changes
+        for (const auto& [hash, index] : mapQueuedChanges)
+        {
+            if (!txdb.UpdateTxIndex(hash, index))
+                return error("%s: UpdateTxIndex failed", __func__);
+        }
     }
 
     // Update block index on disk without changing it in memory.