Revert "[refactor] rewrite vTxHashes as a vector of CTransactionRef"

This reverts commit a03aef9.

Author: ajtowns

src/blockencodings.cpp

@@ -114,12 +114,12 @@ ReadStatus PartiallyDownloadedBlock::InitData(const CBlockHeaderAndShortTxIDs& c
     std::vector<bool> have_txn(txn_available.size());
     {
     LOCK(pool->cs);
-    for (const auto& tx : pool->txns_randomized) {
-        uint64_t shortid = cmpctblock.GetShortID(tx->GetWitnessHash());
+    for (const auto& [wtxid, txit] : pool->txns_randomized) {
+        uint64_t shortid = cmpctblock.GetShortID(wtxid);
         std::unordered_map<uint64_t, uint16_t>::iterator idit = shorttxids.find(shortid);
         if (idit != shorttxids.end()) {
             if (!have_txn[idit->second]) {
-                txn_available[idit->second] = tx;
+                txn_available[idit->second] = txit->GetSharedTx();
                 have_txn[idit->second]  = true;
                 mempool_count++;
             } else {

src/test/blockencodings_tests.cpp

@@ -56,8 +56,8 @@ static CBlock BuildBlockTestCase(FastRandomContext& ctx) {
 }
 
 // Number of shared use_counts we expect for a tx we haven't touched
-// (block + mempool entry + mempool txns_randomized + our copy from the GetSharedTx call)
-constexpr long SHARED_TX_OFFSET{4};
+// (block + mempool entry + our copy from the GetSharedTx call)
+constexpr long SHARED_TX_OFFSET{3};
 
 BOOST_AUTO_TEST_CASE(SimpleRoundTripTest)
 {

src/txmempool.cpp

@@ -507,7 +507,7 @@ void CTxMemPool::addNewTransaction(CTxMemPool::txiter newit, CTxMemPool::setEntr
     totalTxSize += entry.GetTxSize();
     m_total_fee += entry.GetFee();
 
-    txns_randomized.emplace_back(newit->GetSharedTx());
+    txns_randomized.emplace_back(tx.GetWitnessHash(), newit);
     newit->idx_randomized = txns_randomized.size() - 1;
 
     TRACEPOINT(mempool, added,
@@ -544,15 +544,16 @@ void CTxMemPool::removeUnchecked(txiter it, MemPoolRemovalReason reason)
     RemoveUnbroadcastTx(it->GetTx().GetHash(), true /* add logging because unchecked */);
 
     if (txns_randomized.size() > 1) {
-        // Update idx_randomized of the to-be-moved entry.
-        Assert(GetEntry(txns_randomized.back()->GetHash()))->idx_randomized = it->idx_randomized;
         // Remove entry from txns_randomized by replacing it with the back and deleting the back.
         txns_randomized[it->idx_randomized] = std::move(txns_randomized.back());
+        txns_randomized[it->idx_randomized].second->idx_randomized = it->idx_randomized;
         txns_randomized.pop_back();
-        if (txns_randomized.size() * 2 < txns_randomized.capacity())
+        if (txns_randomized.size() * 2 < txns_randomized.capacity()) {
             txns_randomized.shrink_to_fit();
-    } else
+        }
+    } else {
         txns_randomized.clear();
+    }
 
     totalTxSize -= it->GetTxSize();
     m_total_fee -= it->GetFee();

src/txmempool.h

@@ -368,7 +368,7 @@ class CTxMemPool
     indexed_transaction_set mapTx GUARDED_BY(cs);
 
     using txiter = indexed_transaction_set::nth_index<0>::type::const_iterator;
-    std::vector<CTransactionRef> txns_randomized GUARDED_BY(cs); //!< All transactions in mapTx, in random order
+    std::vector<std::pair<Wtxid, txiter>> txns_randomized GUARDED_BY(cs); //!< All transactions in mapTx with their wtxids, in arbitrary order
 
     typedef std::set<txiter, CompareIteratorByHash> setEntries;