Use fee/priority estimates in wallet CreateTransaction

The wallet now uses the mempool fee estimator with a new
command-line option: -txconfirmtarget (default: 1) instead
of using hard-coded fees or priorities.

A new bitcoind that hasn't seen enough transactions to estimate
will fall back to the old hard-coded minimum priority or
transaction fee.

-paytxfee option overrides -txconfirmtarget.

Relaying and mining code isn't changed.

For Qt, the coin control dialog now uses priority estimates to
label transaction priority (instead of hard-coded constants);
unspent outputs were consistently labeled with a much higher
priority than is justified by the free transactions actually
being accepted into blocks.

I did not implement any GUI for setting -txconfirmtarget; I would
suggest getting rid of the "Pay transaction fee" GUI and replace
it with either "target number of confirmations" or maybe
a "faster confirmation <--> lower fee" slider or select box.

1 files changed, 4 insertions, 9 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 04d9523e26..6be1a29c6c 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -858,7 +858,7 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state)
     return true;
 }
 
-int64_t GetMinFee(const CTransaction& tx, unsigned int nBytes, bool fAllowFree, enum GetMinFee_mode mode)
+int64_t GetMinRelayFee(const CTransaction& tx, unsigned int nBytes, bool fAllowFree)
 {
     {
         LOCK(mempool.cs);
@@ -870,10 +870,7 @@ int64_t GetMinFee(const CTransaction& tx, unsigned int nBytes, bool fAllowFree,
             return 0;
     }
 
-    // Base fee is either minTxFee or minRelayTxFee
-    CFeeRate baseFeeRate = (mode == GMF_RELAY) ? tx.minRelayTxFee : tx.minTxFee;
-
-    int64_t nMinFee = baseFeeRate.GetFee(nBytes);
+    int64_t nMinFee = tx.minRelayTxFee.GetFee(nBytes);
 
     if (fAllowFree)
     {
@@ -881,9 +878,7 @@ int64_t GetMinFee(const CTransaction& tx, unsigned int nBytes, bool fAllowFree,
         // * If we are relaying we allow transactions up to DEFAULT_BLOCK_PRIORITY_SIZE - 1000
         //   to be considered to fall into this category. We don't want to encourage sending
         //   multiple transactions instead of one big transaction to avoid fees.
-        // * If we are creating a transaction we allow transactions up to 1,000 bytes
-        //   to be considered safe and assume they can likely make it into this section.
-        if (nBytes < (mode == GMF_SEND ? 1000 : (DEFAULT_BLOCK_PRIORITY_SIZE - 1000)))
+        if (nBytes < (DEFAULT_BLOCK_PRIORITY_SIZE - 1000))
             nMinFee = 0;
     }
 
@@ -1005,7 +1000,7 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
         unsigned int nSize = entry.GetTxSize();
 
         // Don't accept it if it can't get into a block
-        int64_t txMinFee = GetMinFee(tx, nSize, true, GMF_RELAY);
+        int64_t txMinFee = GetMinRelayFee(tx, nSize, true);
         if (fLimitFree && nFees < txMinFee)
             return state.DoS(0, error("AcceptToMemoryPool : not enough fees %s, %d < %d",
                                       hash.ToString(), nFees, txMinFee),