[net processing] Default initialize m_recent_confirmed_transactions

Now that m_recent_confirmed_transactions is owned by PeerManagerImpl,
and PeerManagerImpl's lifetime is managed by the node context, we can
just default initialize m_recent_confirmed_transactions during object
initialization. We can also remove the unique_ptr indirection.

Author: jnewbery

src/net_processing.cpp

@@ -477,9 +477,19 @@ class PeerManagerImpl final : public PeerManager
      * Filter for transactions that have been recently confirmed.
      * We use this to avoid requesting transactions that have already been
      * confirnmed.
+     *
+     * Blocks don't typically have more than 4000 transactions, so this should
+     * be at least six blocks (~1 hr) worth of transactions that we can store,
+     * inserting both a txid and wtxid for every observed transaction.
+     * If the number of transactions appearing in a block goes up, or if we are
+     * seeing getdata requests more than an hour after initial announcement, we
+     * can increase this number.
+     * The false positive rate of 1/1M should come out to less than 1
+     * transaction per day that would be inadvertently ignored (which is the
+     * same probability that we have in the reject filter).
      */
     Mutex m_recent_confirmed_transactions_mutex;
-    std::unique_ptr<CRollingBloomFilter> m_recent_confirmed_transactions GUARDED_BY(m_recent_confirmed_transactions_mutex);
+    CRollingBloomFilter m_recent_confirmed_transactions GUARDED_BY(m_recent_confirmed_transactions_mutex){48'000, 0.000'001};
 
     /** Have we requested this block from a peer */
     bool IsBlockRequested(const uint256& hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
@@ -1396,17 +1406,6 @@ PeerManagerImpl::PeerManagerImpl(const CChainParams& chainparams, CConnman& conn
       m_mempool(pool),
       m_ignore_incoming_txs(ignore_incoming_txs)
 {
-    // Blocks don't typically have more than 4000 transactions, so this should
-    // be at least six blocks (~1 hr) worth of transactions that we can store,
-    // inserting both a txid and wtxid for every observed transaction.
-    // If the number of transactions appearing in a block goes up, or if we are
-    // seeing getdata requests more than an hour after initial announcement, we
-    // can increase this number.
-    // The false positive rate of 1/1M should come out to less than 1
-    // transaction per day that would be inadvertently ignored (which is the
-    // same probability that we have in the reject filter).
-    m_recent_confirmed_transactions.reset(new CRollingBloomFilter(48000, 0.000001));
-
     // Stale tip checking and peer eviction are on two different timers, but we
     // don't want them to get out of sync due to drift in the scheduler, so we
     // combine them in one function and schedule at the quicker (peer-eviction)
@@ -1432,9 +1431,9 @@ void PeerManagerImpl::BlockConnected(const std::shared_ptr<const CBlock>& pblock
     {
         LOCK(m_recent_confirmed_transactions_mutex);
         for (const auto& ptx : pblock->vtx) {
-            m_recent_confirmed_transactions->insert(ptx->GetHash());
+            m_recent_confirmed_transactions.insert(ptx->GetHash());
             if (ptx->GetHash() != ptx->GetWitnessHash()) {
-                m_recent_confirmed_transactions->insert(ptx->GetWitnessHash());
+                m_recent_confirmed_transactions.insert(ptx->GetWitnessHash());
             }
         }
     }
@@ -1458,7 +1457,7 @@ void PeerManagerImpl::BlockDisconnected(const std::shared_ptr<const CBlock> &blo
     // presumably the most common case of relaying a confirmed transaction
     // should be just after a new block containing it is found.
     LOCK(m_recent_confirmed_transactions_mutex);
-    m_recent_confirmed_transactions->reset();
+    m_recent_confirmed_transactions.reset();
 }
 
 // All of the following cache a recent block, and are protected by cs_most_recent_block
@@ -1613,7 +1612,7 @@ bool PeerManagerImpl::AlreadyHaveTx(const GenTxid& gtxid)
 
     {
         LOCK(m_recent_confirmed_transactions_mutex);
-        if (m_recent_confirmed_transactions->contains(hash)) return true;
+        if (m_recent_confirmed_transactions.contains(hash)) return true;
     }
 
     return m_recent_rejects.contains(hash) || m_mempool.exists(gtxid);