mempool: Pass in -mempoolexpiry instead of referencing gArgs

- Store the mempool expiry (-mempoolexpiry) in CTxMemPool as a
  std::chrono::seconds member.

- Remove the requirement to explicitly specify a mempool expiry for
  LimitMempoolSize(...), just use the newly-introduced member.

- Remove all now-unnecessary instances of:
    std::chrono::hours{gArgs.GetIntArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY)}

src/kernel/mempool_options.h

@@ -4,12 +4,15 @@
 #ifndef BITCOIN_KERNEL_MEMPOOL_OPTIONS_H
 #define BITCOIN_KERNEL_MEMPOOL_OPTIONS_H
 
+#include <chrono>
 #include <cstdint>
 
 class CBlockPolicyEstimator;
 
 /** Default for -maxmempool, maximum megabytes of mempool memory usage */
 static constexpr unsigned int DEFAULT_MAX_MEMPOOL_SIZE_MB{300};
+/** Default for -mempoolexpiry, expiration time for mempool transactions in hours */
+static constexpr unsigned int DEFAULT_MEMPOOL_EXPIRY{336};
 
 namespace kernel {
 /**
@@ -25,6 +28,7 @@ struct MemPoolOptions {
     /* The ratio used to determine how often sanity checks will run.  */
     int check_ratio{0};
     int64_t max_size_bytes{DEFAULT_MAX_MEMPOOL_SIZE_MB * 1'000'000};
+    std::chrono::seconds expiry{std::chrono::hours{DEFAULT_MEMPOOL_EXPIRY}};
 };
 } // namespace kernel
 

src/mempool_args.cpp

@@ -15,4 +15,6 @@ void ApplyArgsManOptions(const ArgsManager& argsman, MemPoolOptions& mempool_opt
     mempool_opts.check_ratio = argsman.GetIntArg("-checkmempool", mempool_opts.check_ratio);
 
     if (auto mb = argsman.GetIntArg("-maxmempool")) mempool_opts.max_size_bytes = *mb * 1'000'000;
+
+    if (auto hours = argsman.GetIntArg("-mempoolexpiry")) mempool_opts.expiry = std::chrono::hours{*hours};
 }

src/txmempool.cpp

@@ -454,7 +454,8 @@ void CTxMemPoolEntry::UpdateAncestorState(int64_t modifySize, CAmount modifyFee,
 CTxMemPool::CTxMemPool(const Options& opts)
     : m_check_ratio{opts.check_ratio},
       minerPolicyEstimator{opts.estimator},
-      m_max_size_bytes{opts.max_size_bytes}
+      m_max_size_bytes{opts.max_size_bytes},
+      m_expiry{opts.expiry}
 {
     _clear(); //lock free clear
 }

src/txmempool.h

@@ -567,6 +567,7 @@ public:
     using Options = kernel::MemPoolOptions;
 
     const int64_t m_max_size_bytes;
+    const std::chrono::seconds m_expiry;
 
     /** Create a new CTxMemPool.
      * Sanity checks will be off by default for performance, because otherwise

src/validation.cpp

@@ -255,12 +255,12 @@ bool CheckSequenceLocksAtTip(CBlockIndex* tip,
 // Returns the script flags which should be checked for a given block
 static unsigned int GetBlockScriptFlags(const CBlockIndex& block_index, const ChainstateManager& chainman);
 
-static void LimitMempoolSize(CTxMemPool& pool, CCoinsViewCache& coins_cache, std::chrono::seconds age)
+static void LimitMempoolSize(CTxMemPool& pool, CCoinsViewCache& coins_cache)
     EXCLUSIVE_LOCKS_REQUIRED(::cs_main, pool.cs)
 {
     AssertLockHeld(::cs_main);
     AssertLockHeld(pool.cs);
-    int expired = pool.Expire(GetTime<std::chrono::seconds>() - age);
+    int expired = pool.Expire(GetTime<std::chrono::seconds>() - pool.m_expiry);
     if (expired != 0) {
         LogPrint(BCLog::MEMPOOL, "Expired %i transactions from the memory pool\n", expired);
     }
@@ -374,10 +374,7 @@ void CChainState::MaybeUpdateMempoolForReorg(
     // We also need to remove any now-immature transactions
     m_mempool->removeForReorg(m_chain, filter_final_and_mature);
     // Re-limit mempool size, in case we added any transactions
-    LimitMempoolSize(
-        *m_mempool,
-        this->CoinsTip(),
-        std::chrono::hours{gArgs.GetIntArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY)});
+    LimitMempoolSize(*m_mempool, this->CoinsTip());
 }
 
 /**
@@ -1081,7 +1078,7 @@ bool MemPoolAccept::Finalize(const ATMPArgs& args, Workspace& ws)
     // in the package. LimitMempoolSize() should be called at the very end to make sure the mempool
     // is still within limits and package submission happens atomically.
     if (!args.m_package_submission && !bypass_limits) {
-        LimitMempoolSize(m_pool, m_active_chainstate.CoinsTip(), std::chrono::hours{gArgs.GetIntArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY)});
+        LimitMempoolSize(m_pool, m_active_chainstate.CoinsTip());
         if (!m_pool.exists(GenTxid::Txid(hash)))
             return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "mempool full");
     }
@@ -1146,8 +1143,7 @@ bool MemPoolAccept::SubmitPackage(const ATMPArgs& args, std::vector<Workspace>&
 
     // It may or may not be the case that all the transactions made it into the mempool. Regardless,
     // make sure we haven't exceeded max mempool size.
-    LimitMempoolSize(m_pool, m_active_chainstate.CoinsTip(),
-                     std::chrono::hours{gArgs.GetIntArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY)});
+    LimitMempoolSize(m_pool, m_active_chainstate.CoinsTip());
 
     // Find the wtxids of the transactions that made it into the mempool. Allow partial submission,
     // but don't report success unless they all made it into the mempool.
@@ -4645,7 +4641,7 @@ static const uint64_t MEMPOOL_DUMP_VERSION = 1;
 
 bool LoadMempool(CTxMemPool& pool, CChainState& active_chainstate, FopenFn mockable_fopen_function)
 {
-    int64_t nExpiryTimeout = gArgs.GetIntArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60;
+    int64_t nExpiryTimeout = std::chrono::seconds{pool.m_expiry}.count();
     FILE* filestr{mockable_fopen_function(gArgs.GetDataDirNet() / "mempool.dat", "rb")};
     CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
     if (file.IsNull()) {

src/validation.h

@@ -59,8 +59,6 @@ namespace Consensus {
 struct Params;
 } // namespace Consensus
 
-/** Default for -mempoolexpiry, expiration time for mempool transactions in hours */
-static const unsigned int DEFAULT_MEMPOOL_EXPIRY = 336;
 /** Maximum number of dedicated script-checking threads allowed */
 static const int MAX_SCRIPTCHECK_THREADS = 15;
 /** -par default (number of script-checking threads, 0 = auto) */