mempool: Pass in -maxmempool instead of referencing gArgs

- Store the mempool size limit (-maxmempool) in CTxMemPool as a member.

- Remove the requirement to explicitly specify a mempool size limit for
  CTxMemPool::GetMinFee(...) and LimitMempoolSize(...), just use the
  stored mempool size limit where possible.

- Remove all now-unnecessary instances of:
    gArgs.GetIntArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE_MB) * 1000000

The code change in CChainState::GetCoinsCacheSizeState() is correct
since the coinscache should not repurpose "extra" mempool memory
headroom for itself if the mempool doesn't even exist.

2 files changed, 3 insertions, 4 deletions

diff --git a/src/rpc/fees.cpp b/src/rpc/fees.cpp
index e6e8324c27..dd1a6441a0 100644
--- a/src/rpc/fees.cpp
+++ b/src/rpc/fees.cpp
@@ -89,7 +89,7 @@ static RPCHelpMan estimatesmartfee()
             FeeCalculation feeCalc;
             CFeeRate feeRate{fee_estimator.estimateSmartFee(conf_target, &feeCalc, conservative)};
             if (feeRate != CFeeRate(0)) {
-                CFeeRate min_mempool_feerate{mempool.GetMinFee(gArgs.GetIntArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE_MB) * 1000000)};
+                CFeeRate min_mempool_feerate{mempool.GetMinFee()};
                 CFeeRate min_relay_feerate{::minRelayTxFee};
                 feeRate = std::max({feeRate, min_mempool_feerate, min_relay_feerate});
                 result.pushKV("feerate", ValueFromAmount(feeRate.GetFeePerK()));
diff --git a/src/rpc/mempool.cpp b/src/rpc/mempool.cpp
index 07b12bc047..2cdde14144 100644
--- a/src/rpc/mempool.cpp
+++ b/src/rpc/mempool.cpp
@@ -657,9 +657,8 @@ UniValue MempoolInfoToJSON(const CTxMemPool& pool)
     ret.pushKV("bytes", (int64_t)pool.GetTotalTxSize());
     ret.pushKV("usage", (int64_t)pool.DynamicMemoryUsage());
     ret.pushKV("total_fee", ValueFromAmount(pool.GetTotalFee()));
-    int64_t maxmempool{gArgs.GetIntArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE_MB) * 1000000};
-    ret.pushKV("maxmempool", maxmempool);
-    ret.pushKV("mempoolminfee", ValueFromAmount(std::max(pool.GetMinFee(maxmempool), ::minRelayTxFee).GetFeePerK()));
+    ret.pushKV("maxmempool", pool.m_max_size_bytes);
+    ret.pushKV("mempoolminfee", ValueFromAmount(std::max(pool.GetMinFee(), ::minRelayTxFee).GetFeePerK()));
     ret.pushKV("minrelaytxfee", ValueFromAmount(::minRelayTxFee.GetFeePerK()));
     ret.pushKV("unbroadcastcount", uint64_t{pool.GetUnbroadcastTxs().size()});
     return ret;