[Mempool] Fix mempool limiting and replace-by-fee for PrioritiseTransaction

1) Fix mempool limiting for PrioritiseTransaction

Redo the feerate index to be based on mining score, rather than fee.

Update mempool_packages.py to test prioritisetransaction's effect on
package scores.

2) Update replace-by-fee logic to use fee deltas

3) Use fee deltas for determining mempool acceptance

4) Remove GetMinRelayFee

One test in AcceptToMemoryPool was to compare a transaction's fee
agains the value returned by GetMinRelayFee. This value was zero for
all small transactions.  For larger transactions (between
DEFAULT_BLOCK_PRIORITY_SIZE and MAX_STANDARD_TX_SIZE), this function
was preventing low fee transactions from ever being accepted.

With this function removed, we will now allow transactions in that range
with fees (including modifications via PrioritiseTransaction) below
the minRelayTxFee, provided that they have sufficient priority.

Github-Pull: #7062
Rebased-From: eb306664e786ae43d539fde66f0fbe2a3e89d910 9ef2a25603c9ec4e44c4f45c6a5d4e4386ec86d3 27fae3484cdb21b0d24face833b966fce5926be5 901b01d674031f9aca717deeb372bafa160a24af

1 files changed, 24 insertions, 0 deletions

diff --git a/qa/rpc-tests/mempool_packages.py b/qa/rpc-tests/mempool_packages.py
index 34b316a6a3..063308d394 100755
--- a/qa/rpc-tests/mempool_packages.py
+++ b/qa/rpc-tests/mempool_packages.py
@@ -64,17 +64,41 @@ class MempoolPackagesTest(BitcoinTestFramework):
         for x in reversed(chain):
             assert_equal(mempool[x]['descendantcount'], descendant_count)
             descendant_fees += mempool[x]['fee']
+            assert_equal(mempool[x]['modifiedfee'], mempool[x]['fee'])
             assert_equal(mempool[x]['descendantfees'], SATOSHIS*descendant_fees)
             descendant_size += mempool[x]['size']
             assert_equal(mempool[x]['descendantsize'], descendant_size)
             descendant_count += 1
 
+        # Check that descendant modified fees includes fee deltas from
+        # prioritisetransaction
+        self.nodes[0].prioritisetransaction(chain[-1], 0, 1000)
+        mempool = self.nodes[0].getrawmempool(True)
+
+        descendant_fees = 0
+        for x in reversed(chain):
+            descendant_fees += mempool[x]['fee']
+            assert_equal(mempool[x]['descendantfees'], SATOSHIS*descendant_fees+1000)
+
         # Adding one more transaction on to the chain should fail.
         try:
             self.chain_transaction(self.nodes[0], txid, vout, value, fee, 1)
         except JSONRPCException as e:
             print "too-long-ancestor-chain successfully rejected"
 
+        # Check that prioritising a tx before it's added to the mempool works
+        self.nodes[0].generate(1)
+        self.nodes[0].prioritisetransaction(chain[-1], 0, 2000)
+        self.nodes[0].invalidateblock(self.nodes[0].getbestblockhash())
+        mempool = self.nodes[0].getrawmempool(True)
+
+        descendant_fees = 0
+        for x in reversed(chain):
+            descendant_fees += mempool[x]['fee']
+            if (x == chain[-1]):
+                assert_equal(mempool[x]['modifiedfee'], mempool[x]['fee']+satoshi_round(0.00002))
+            assert_equal(mempool[x]['descendantfees'], SATOSHIS*descendant_fees+2000)
+
         # TODO: check that node1's mempool is as expected
 
         # TODO: test ancestor size limits