[mempool] Persist unbroadcast set to mempool.dat

Ensure that the unbroadcast set will still be meaningful if the node is
restarted.

src/validation.cpp

@@ -4970,6 +4970,7 @@ bool LoadMempool(CTxMemPool& pool)
     int64_t expired = 0;
     int64_t failed = 0;
     int64_t already_there = 0;
+    int64_t unbroadcast = 0;
     int64_t nNow = GetTime();
 
     try {
@@ -5023,12 +5024,21 @@ bool LoadMempool(CTxMemPool& pool)
         for (const auto& i : mapDeltas) {
             pool.PrioritiseTransaction(i.first, i.second);
         }
+
+        std::set<uint256> unbroadcast_txids;
+        file >> unbroadcast_txids;
+        unbroadcast = unbroadcast_txids.size();
+
+        for (const auto& txid : unbroadcast_txids) {
+            pool.AddUnbroadcastTx(txid);
+        }
+
     } catch (const std::exception& e) {
         LogPrintf("Failed to deserialize mempool data on disk: %s. Continuing anyway.\n", e.what());
         return false;
     }
 
-    LogPrintf("Imported mempool transactions from disk: %i succeeded, %i failed, %i expired, %i already there\n", count, failed, expired, already_there);
+    LogPrintf("Imported mempool transactions from disk: %i succeeded, %i failed, %i expired, %i already there, %i waiting for initial broadcast\n", count, failed, expired, already_there, unbroadcast);
     return true;
 }
 
@@ -5038,6 +5048,7 @@ bool DumpMempool(const CTxMemPool& pool)
 
     std::map<uint256, CAmount> mapDeltas;
     std::vector<TxMempoolInfo> vinfo;
+    std::set<uint256> unbroadcast_txids;
 
     static Mutex dump_mutex;
     LOCK(dump_mutex);
@@ -5048,6 +5059,7 @@ bool DumpMempool(const CTxMemPool& pool)
             mapDeltas[i.first] = i.second;
         }
         vinfo = pool.infoAll();
+        unbroadcast_txids = pool.GetUnbroadcastTxs();
     }
 
     int64_t mid = GetTimeMicros();
@@ -5072,6 +5084,10 @@ bool DumpMempool(const CTxMemPool& pool)
         }
 
         file << mapDeltas;
+
+        LogPrintf("Writing %d unbroadcast transactions to disk.\n", unbroadcast_txids.size());
+        file << unbroadcast_txids;
+
         if (!FileCommit(file.Get()))
             throw std::runtime_error("FileCommit failed");
         file.fclose();

test/functional/mempool_persist.py

@@ -40,10 +40,13 @@ import os
 import time
 
 from test_framework.test_framework import BitcoinTestFramework
+from test_framework.mininode import P2PTxInvStore
 from test_framework.util import (
     assert_equal,
     assert_greater_than_or_equal,
     assert_raises_rpc_error,
+    connect_nodes,
+    disconnect_nodes,
     wait_until,
 )
 
@@ -80,6 +83,11 @@ class MempoolPersistTest(BitcoinTestFramework):
         assert_greater_than_or_equal(tx_creation_time, tx_creation_time_lower)
         assert_greater_than_or_equal(tx_creation_time_higher, tx_creation_time)
 
+        # disconnect nodes & make a txn that remains in the unbroadcast set.
+        disconnect_nodes(self.nodes[0], 2)
+        self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), Decimal("12"))
+        connect_nodes(self.nodes[0], 2)
+
         self.log.debug("Stop-start the nodes. Verify that node0 has the transactions in its mempool and node1 does not. Verify that node2 calculates its balance correctly after loading wallet transactions.")
         self.stop_nodes()
         # Give this node a head-start, so we can be "extra-sure" that it didn't load anything later
@@ -89,7 +97,7 @@ class MempoolPersistTest(BitcoinTestFramework):
         self.start_node(2)
         wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"], timeout=1)
         wait_until(lambda: self.nodes[2].getmempoolinfo()["loaded"], timeout=1)
-        assert_equal(len(self.nodes[0].getrawmempool()), 5)
+        assert_equal(len(self.nodes[0].getrawmempool()), 6)
         assert_equal(len(self.nodes[2].getrawmempool()), 5)
         # The others have loaded their mempool. If node_1 loaded anything, we'd probably notice by now:
         assert_equal(len(self.nodes[1].getrawmempool()), 0)
@@ -105,9 +113,10 @@ class MempoolPersistTest(BitcoinTestFramework):
         self.nodes[2].syncwithvalidationinterfacequeue()  # Flush mempool to wallet
         assert_equal(node2_balance, self.nodes[2].getbalance())
 
+        # start node0 with wallet disabled so wallet transactions don't get resubmitted
         self.log.debug("Stop-start node0 with -persistmempool=0. Verify that it doesn't load its mempool.dat file.")
         self.stop_nodes()
-        self.start_node(0, extra_args=["-persistmempool=0"])
+        self.start_node(0, extra_args=["-persistmempool=0", "-disablewallet"])
         wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"])
         assert_equal(len(self.nodes[0].getrawmempool()), 0)
 
@@ -115,7 +124,7 @@ class MempoolPersistTest(BitcoinTestFramework):
         self.stop_nodes()
         self.start_node(0)
         wait_until(lambda: self.nodes[0].getmempoolinfo()["loaded"])
-        assert_equal(len(self.nodes[0].getrawmempool()), 5)
+        assert_equal(len(self.nodes[0].getrawmempool()), 6)
 
         mempooldat0 = os.path.join(self.nodes[0].datadir, self.chain, 'mempool.dat')
         mempooldat1 = os.path.join(self.nodes[1].datadir, self.chain, 'mempool.dat')
@@ -124,12 +133,12 @@ class MempoolPersistTest(BitcoinTestFramework):
         self.nodes[0].savemempool()
         assert os.path.isfile(mempooldat0)
 
-        self.log.debug("Stop nodes, make node1 use mempool.dat from node0. Verify it has 5 transactions")
+        self.log.debug("Stop nodes, make node1 use mempool.dat from node0. Verify it has 6 transactions")
         os.rename(mempooldat0, mempooldat1)
         self.stop_nodes()
         self.start_node(1, extra_args=[])
         wait_until(lambda: self.nodes[1].getmempoolinfo()["loaded"])
-        assert_equal(len(self.nodes[1].getrawmempool()), 5)
+        assert_equal(len(self.nodes[1].getrawmempool()), 6)
 
         self.log.debug("Prevent bitcoind from writing mempool.dat to disk. Verify that `savemempool` fails")
         # to test the exception we are creating a tmp folder called mempool.dat.new
@@ -139,6 +148,27 @@ class MempoolPersistTest(BitcoinTestFramework):
         assert_raises_rpc_error(-1, "Unable to dump mempool to disk", self.nodes[1].savemempool)
         os.rmdir(mempooldotnew1)
 
+        self.test_persist_unbroadcast()
+
+    def test_persist_unbroadcast(self):
+        node0 = self.nodes[0]
+        self.start_node(0)
+
+        # clear out mempool
+        node0.generate(1)
+
+        # disconnect nodes to make a txn that remains in the unbroadcast set.
+        disconnect_nodes(node0, 1)
+        node0.sendtoaddress(self.nodes[1].getnewaddress(), Decimal("12"))
+
+        # shutdown, then startup with wallet disabled
+        self.stop_nodes()
+        self.start_node(0, extra_args=["-disablewallet"])
+
+        # check that txn gets broadcast due to unbroadcast logic
+        conn = node0.add_p2p_connection(P2PTxInvStore())
+        node0.mockscheduler(16*60) # 15 min + 1 for buffer
+        wait_until(lambda: len(conn.get_invs()) == 1)
 
 if __name__ == '__main__':
     MempoolPersistTest().main()

test/functional/mempool_unbroadcast.py

@@ -58,6 +58,9 @@ class MempoolUnbroadcastTest(BitcoinTestFramework):
         assert rpc_tx_hsh not in mempool
         assert wallet_tx_hsh not in mempool
 
+        # ensure that unbroadcast txs are persisted to mempool.dat
+        self.restart_node(0)
+
         self.log.info("Reconnect nodes & check if they are sent to node 1")
         connect_nodes(node, 1)