Add sane fallback for fee estimation

- Always respect GetRequiredFee for wallet txs
- Add sane fallback for fee estimation
- SQUASHME: Fix rpc tests that assumed fallback to minRelayTxFee

Add new commandline option "-fallbackfee" to use when fee estimation does not have sufficient data.

Github-Pull: #7296
Rebased-From: 995b9f3 e420a1b bebe58b

1 files changed, 11 insertions, 0 deletions

diff --git a/src/init.cpp b/src/init.cpp
index 60b6194b3c..47d1271248 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -393,6 +393,8 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageGroup(_("Wallet options:"));
     strUsage += HelpMessageOpt("-disablewallet", _("Do not load the wallet and disable wallet RPC calls"));
     strUsage += HelpMessageOpt("-keypool=<n>", strprintf(_("Set key pool size to <n> (default: %u)"), DEFAULT_KEYPOOL_SIZE));
+    strUsage += HelpMessageOpt("-fallbackfee=<amt>", strprintf(_("A fee rate (in %s/kB) that will be used when fee estimation has insufficient data (default: %s)"),
+        CURRENCY_UNIT, FormatMoney(DEFAULT_FALLBACK_FEE)));
     strUsage += HelpMessageOpt("-mintxfee=<amt>", strprintf(_("Fees (in %s/kB) smaller than this are considered zero fee for transaction creation (default: %s)"),
             CURRENCY_UNIT, FormatMoney(DEFAULT_TRANSACTION_MINFEE)));
     strUsage += HelpMessageOpt("-paytxfee=<amt>", strprintf(_("Fee (in %s/kB) to add to transactions you send (default: %s)"),
@@ -949,6 +951,15 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
         else
             return InitError(strprintf(_("Invalid amount for -mintxfee=<amount>: '%s'"), mapArgs["-mintxfee"]));
     }
+    if (mapArgs.count("-fallbackfee"))
+    {
+        CAmount nFeePerK = 0;
+        if (!ParseMoney(mapArgs["-fallbackfee"], nFeePerK))
+            return InitError(strprintf(_("Invalid amount for -fallbackfee=<amount>: '%s'"), mapArgs["-fallbackfee"]));
+        if (nFeePerK > nHighTransactionFeeWarning)
+            InitWarning(_("-fallbackfee is set very high! This is the transaction fee you may pay when fee estimates are not available."));
+        CWallet::fallbackFee = CFeeRate(nFeePerK);
+    }
     if (mapArgs.count("-paytxfee"))
     {
         CAmount nFeePerK = 0;