Add sane fallback for fee estimation

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

1 files changed, 9 insertions, 0 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 244bc37e76..581c688fc7 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -47,6 +47,12 @@ bool fSendFreeTransactions = DEFAULT_SEND_FREE_TRANSACTIONS;
  * Override with -mintxfee
  */
 CFeeRate CWallet::minTxFee = CFeeRate(DEFAULT_TRANSACTION_MINFEE);
+/**
+ * If fee estimation does not have enough data to provide estimates, use this fee instead.
+ * Has no effect if not using fee estimation
+ * Override with -fallbackfee
+ */
+CFeeRate CWallet::fallbackFee = CFeeRate(DEFAULT_FALLBACK_FEE);
 
 /** @defgroup mapWallet
  *
@@ -2223,6 +2229,9 @@ CAmount CWallet::GetMinimumFee(unsigned int nTxBytes, unsigned int nConfirmTarge
     if (nFeeNeeded == 0) {
         int estimateFoundTarget = nConfirmTarget;
         nFeeNeeded = pool.estimateSmartFee(nConfirmTarget, &estimateFoundTarget).GetFee(nTxBytes);
+        // ... unless we don't have enough mempool data for estimatefee, then use fallbackFee
+        if (nFeeNeeded == 0)
+            nFeeNeeded = fallbackFee.GetFee(nTxBytes);
     }
     // prevent user from paying a fee below minRelayTxFee or minTxFee
     nFeeNeeded = std::max(nFeeNeeded, GetRequiredFee(nTxBytes));