Merge bitcoin#30186: fuzz: increase txorphan harness stability

8defc18 scripted-diff: Replace nNextSweep with m_next_sweep (marcofleon)
0048680 increase txorphan harness stability (marcofleon)

Pull request description:

  This moves `nNextSweep` from being a static variable in `LimitOrphans` to being a member of the `TxOrphanage` class. This improves the stability of the `txorphan` fuzz harness, as each orphanage (created every iteration) now has its own value for `nNextSweep`.

ACKs for top commit:
  maflcko:
    utACK 8defc18
  dergoegge:
    Code review ACK 8defc18
  glozow:
    utACK 8defc18, I can rebase on this pretty easily

Tree-SHA512: 54d4a5074def764f6c895308b94e417662d2f21f157925421131745f22743907df59971f4ce545063658cd74ec133792cdd8df96ae3e69af8314e9b0ff899d48

src/txorphanage.cpp

@@ -119,9 +119,8 @@ void TxOrphanage::LimitOrphans(unsigned int max_orphans, FastRandomContext& rng)
     LOCK(m_mutex);
 
     unsigned int nEvicted = 0;
-    static NodeSeconds nNextSweep;
     auto nNow{Now<NodeSeconds>()};
-    if (nNextSweep <= nNow) {
+    if (m_next_sweep <= nNow) {
         // Sweep out expired orphan pool entries:
         int nErased = 0;
         auto nMinExpTime{nNow + ORPHAN_TX_EXPIRE_TIME - ORPHAN_TX_EXPIRE_INTERVAL};
@@ -136,7 +135,7 @@ void TxOrphanage::LimitOrphans(unsigned int max_orphans, FastRandomContext& rng)
             }
         }
         // Sweep again 5 minutes after the next entry that expires in order to batch the linear scan.
-        nNextSweep = nMinExpTime + ORPHAN_TX_EXPIRE_INTERVAL;
+        m_next_sweep = nMinExpTime + ORPHAN_TX_EXPIRE_INTERVAL;
         if (nErased > 0) LogPrint(BCLog::TXPACKAGES, "Erased %d orphan tx due to expiration\n", nErased);
     }
     while (m_orphans.size() > max_orphans)

src/txorphanage.h

@@ -105,6 +105,9 @@ class TxOrphanage {
 
     /** Erase an orphan by wtxid */
     int EraseTxNoLock(const Wtxid& wtxid) EXCLUSIVE_LOCKS_REQUIRED(m_mutex);
+
+    /** Timestamp for the next scheduled sweep of expired orphans */
+    NodeSeconds m_next_sweep GUARDED_BY(m_mutex){0s};
 };
 
 #endif // BITCOIN_TXORPHANAGE_H