refactor: Add non-thread-safe CBlockPolicyEstimator::_removeTx helper

This changes removes recursion in the m_cs_fee_estimator locks.

Author: hebasto

src/policy/fees.cpp

@@ -473,6 +473,12 @@ void TxConfirmStats::removeTx(unsigned int entryHeight, unsigned int nBestSeenHe
 bool CBlockPolicyEstimator::removeTx(uint256 hash, bool inBlock)
 {
     LOCK(m_cs_fee_estimator);
+    return _removeTx(hash, inBlock);
+}
+
+bool CBlockPolicyEstimator::_removeTx(const uint256& hash, bool inBlock)
+{
+    AssertLockHeld(m_cs_fee_estimator);
     std::map<uint256, TxStatsInfo>::iterator pos = mapMemPoolTxs.find(hash);
     if (pos != mapMemPoolTxs.end()) {
         feeStats->removeTx(pos->second.blockHeight, nBestSeenHeight, pos->second.bucketIndex, inBlock);
@@ -556,7 +562,8 @@ void CBlockPolicyEstimator::processTransaction(const CTxMemPoolEntry& entry, boo
 
 bool CBlockPolicyEstimator::processBlockTx(unsigned int nBlockHeight, const CTxMemPoolEntry* entry)
 {
-    if (!removeTx(entry->GetTx().GetHash(), true)) {
+    AssertLockHeld(m_cs_fee_estimator);
+    if (!_removeTx(entry->GetTx().GetHash(), true)) {
         // This transaction wasn't being tracked for fee estimation
         return false;
     }
@@ -965,7 +972,7 @@ void CBlockPolicyEstimator::FlushUnconfirmed() {
     // Remove every entry in mapMemPoolTxs
     while (!mapMemPoolTxs.empty()) {
         auto mi = mapMemPoolTxs.begin();
-        removeTx(mi->first, false); // this calls erase() on mapMemPoolTxs
+        _removeTx(mi->first, false); // this calls erase() on mapMemPoolTxs
     }
     int64_t endclear = GetTimeMicros();
     LogPrint(BCLog::ESTIMATEFEE, "Recorded %u unconfirmed txs from mempool in %gs\n", num_entries, (endclear - startclear)*0.000001);

src/policy/fees.h

@@ -194,7 +194,8 @@ class CBlockPolicyEstimator
         EXCLUSIVE_LOCKS_REQUIRED(!m_cs_fee_estimator);
 
     /** Remove a transaction from the mempool tracking stats*/
-    bool removeTx(uint256 hash, bool inBlock);
+    bool removeTx(uint256 hash, bool inBlock)
+        EXCLUSIVE_LOCKS_REQUIRED(!m_cs_fee_estimator);
 
     /** DEPRECATED. Return a feerate estimate */
     CFeeRate estimateFee(int confTarget) const
@@ -278,6 +279,10 @@ class CBlockPolicyEstimator
     unsigned int HistoricalBlockSpan() const EXCLUSIVE_LOCKS_REQUIRED(m_cs_fee_estimator);
     /** Calculation of highest target that reasonable estimate can be provided for */
     unsigned int MaxUsableEstimate() const EXCLUSIVE_LOCKS_REQUIRED(m_cs_fee_estimator);
+
+    /** A non-thread-safe helper for the removeTx function */
+    bool _removeTx(const uint256& hash, bool inBlock)
+        EXCLUSIVE_LOCKS_REQUIRED(m_cs_fee_estimator);
 };
 
 class FeeFilterRounder