SelectCoinsMinConf: Prefer coins with fewer ancestors

5 files changed, 65 insertions, 42 deletions

diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 59afb2cf5a..a7056554ad 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -1134,3 +1134,10 @@ void CTxMemPool::TrimToSize(size_t sizelimit, std::vector<uint256>* pvNoSpendsRe
     if (maxFeeRateRemoved > CFeeRate(0))
         LogPrint("mempool", "Removed %u txn, rolling minimum fee bumped to %s\n", nTxnRemoved, maxFeeRateRemoved.ToString());
 }
+
+bool CTxMemPool::TransactionWithinChainLimit(const uint256& txid, size_t chainLimit) const {
+    LOCK(cs);
+    if (exists(txid) && std::max(mapTx.find(txid)->GetCountWithAncestors(), mapTx.find(txid)->GetCountWithDescendants()) >= chainLimit)
+        return false;
+    return true;
+}
diff --git a/src/txmempool.h b/src/txmempool.h
index afb328b5af..8129a05375 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -595,6 +595,9 @@ public:
     /** Expire all transaction (and their dependencies) in the mempool older than time. Return the number of removed transactions. */
     int Expire(int64_t time);
 
+    /** Returns false if the transaction is in the mempool and not within the chain limit specified. */
+    bool TransactionWithinChainLimit(const uint256& txid, size_t chainLimit) const;
+
     unsigned long size()
     {
         LOCK(cs);
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index c6c5058984..38637b2d5c 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -78,24 +78,24 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         empty_wallet();
 
         // with an empty wallet we can't even pay one cent
-        BOOST_CHECK(!wallet.SelectCoinsMinConf( 1 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK(!wallet.SelectCoinsMinConf( 1 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
 
         add_coin(1*CENT, 4);        // add a new 1 cent coin
 
         // with a new 1 cent coin, we still can't find a mature 1 cent
-        BOOST_CHECK(!wallet.SelectCoinsMinConf( 1 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK(!wallet.SelectCoinsMinConf( 1 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
 
         // but we can find a new 1 cent
-        BOOST_CHECK( wallet.SelectCoinsMinConf( 1 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf( 1 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 1 * CENT);
 
         add_coin(2*CENT);           // add a mature 2 cent coin
 
         // we can't make 3 cents of mature coins
-        BOOST_CHECK(!wallet.SelectCoinsMinConf( 3 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK(!wallet.SelectCoinsMinConf( 3 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
 
         // we can make 3 cents of new  coins
-        BOOST_CHECK( wallet.SelectCoinsMinConf( 3 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf( 3 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 3 * CENT);
 
         add_coin(5*CENT);           // add a mature 5 cent coin,
@@ -105,33 +105,33 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         // now we have new: 1+10=11 (of which 10 was self-sent), and mature: 2+5+20=27.  total = 38
 
         // we can't make 38 cents only if we disallow new coins:
-        BOOST_CHECK(!wallet.SelectCoinsMinConf(38 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK(!wallet.SelectCoinsMinConf(38 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
         // we can't even make 37 cents if we don't allow new coins even if they're from us
-        BOOST_CHECK(!wallet.SelectCoinsMinConf(38 * CENT, 6, 6, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK(!wallet.SelectCoinsMinConf(38 * CENT, 6, 6, 0, vCoins, setCoinsRet, nValueRet));
         // but we can make 37 cents if we accept new coins from ourself
-        BOOST_CHECK( wallet.SelectCoinsMinConf(37 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(37 * CENT, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 37 * CENT);
         // and we can make 38 cents if we accept all new coins
-        BOOST_CHECK( wallet.SelectCoinsMinConf(38 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(38 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 38 * CENT);
 
         // try making 34 cents from 1,2,5,10,20 - we can't do it exactly
-        BOOST_CHECK( wallet.SelectCoinsMinConf(34 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(34 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 35 * CENT);       // but 35 cents is closest
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);     // the best should be 20+10+5.  it's incredibly unlikely the 1 or 2 got included (but possible)
 
         // when we try making 7 cents, the smaller coins (1,2,5) are enough.  We should see just 2+5
-        BOOST_CHECK( wallet.SelectCoinsMinConf( 7 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf( 7 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 7 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
         // when we try making 8 cents, the smaller coins (1,2,5) are exactly enough.
-        BOOST_CHECK( wallet.SelectCoinsMinConf( 8 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf( 8 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK(nValueRet == 8 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
 
         // when we try making 9 cents, no subset of smaller coins is enough, and we get the next bigger coin (10)
-        BOOST_CHECK( wallet.SelectCoinsMinConf( 9 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf( 9 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 10 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -145,30 +145,30 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         add_coin(30*CENT); // now we have 6+7+8+20+30 = 71 cents total
 
         // check that we have 71 and not 72
-        BOOST_CHECK( wallet.SelectCoinsMinConf(71 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
-        BOOST_CHECK(!wallet.SelectCoinsMinConf(72 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(71 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK(!wallet.SelectCoinsMinConf(72 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
 
         // now try making 16 cents.  the best smaller coins can do is 6+7+8 = 21; not as good at the next biggest coin, 20
-        BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 20 * CENT); // we should get 20 in one coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
         add_coin( 5*CENT); // now we have 5+6+7+8+20+30 = 75 cents total
 
         // now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, better than the next biggest coin, 20
-        BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 18 * CENT); // we should get 18 in 3 coins
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
 
         add_coin( 18*CENT); // now we have 5+6+7+8+18+20+30
 
         // and now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, the same as the next biggest coin, 18
-        BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 18 * CENT);  // we should get 18 in 1 coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U); // because in the event of a tie, the biggest coin wins
 
         // now try making 11 cents.  we should get 5+6
-        BOOST_CHECK( wallet.SelectCoinsMinConf(11 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(11 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 11 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
@@ -177,11 +177,11 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         add_coin( 2*COIN);
         add_coin( 3*COIN);
         add_coin( 4*COIN); // now we have 5+6+7+8+18+20+30+100+200+300+400 = 1094 cents
-        BOOST_CHECK( wallet.SelectCoinsMinConf(95 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(95 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 1 * COIN);  // we should get 1 BTC in 1 coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
-        BOOST_CHECK( wallet.SelectCoinsMinConf(195 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(195 * CENT, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 2 * COIN);  // we should get 2 BTC in 1 coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -196,14 +196,14 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
 
         // try making 1 * MIN_CHANGE from the 1.5 * MIN_CHANGE
         // we'll get change smaller than MIN_CHANGE whatever happens, so can expect MIN_CHANGE exactly
-        BOOST_CHECK( wallet.SelectCoinsMinConf(MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);
 
         // but if we add a bigger coin, small change is avoided
         add_coin(1111*MIN_CHANGE);
 
         // try making 1 from 0.1 + 0.2 + 0.3 + 0.4 + 0.5 + 1111 = 1112.5
-        BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
 
         // if we add more small coins:
@@ -211,7 +211,7 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         add_coin(MIN_CHANGE * 7 / 10);
 
         // and try again to make 1.0 * MIN_CHANGE
-        BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
 
         // run the 'mtgox' test (see http://blockexplorer.com/tx/29a3efd3ef04f9153d47a990bd7b048a4b2d213daaa5fb8ed670fb85f13bdbcf)
@@ -220,7 +220,7 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         for (int i = 0; i < 20; i++)
             add_coin(50000 * COIN);
 
-        BOOST_CHECK( wallet.SelectCoinsMinConf(500000 * COIN, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(500000 * COIN, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 500000 * COIN); // we should get the exact amount
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 10U); // in ten coins
 
@@ -233,7 +233,7 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         add_coin(MIN_CHANGE * 6 / 10);
         add_coin(MIN_CHANGE * 7 / 10);
         add_coin(1111 * MIN_CHANGE);
-        BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 1111 * MIN_CHANGE); // we get the bigger coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -243,7 +243,7 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         add_coin(MIN_CHANGE * 6 / 10);
         add_coin(MIN_CHANGE * 8 / 10);
         add_coin(1111 * MIN_CHANGE);
-        BOOST_CHECK( wallet.SelectCoinsMinConf(MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK( wallet.SelectCoinsMinConf(MIN_CHANGE, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);   // we should get the exact amount
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U); // in two coins 0.4+0.6
 
@@ -254,12 +254,12 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
         add_coin(MIN_CHANGE * 100);
 
         // trying to make 100.01 from these three coins
-        BOOST_CHECK(wallet.SelectCoinsMinConf(MIN_CHANGE * 10001 / 100, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK(wallet.SelectCoinsMinConf(MIN_CHANGE * 10001 / 100, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE * 10105 / 100); // we should get all coins
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
 
         // but if we try to make 99.9, we should take the bigger of the two small coins to avoid small change
-        BOOST_CHECK(wallet.SelectCoinsMinConf(MIN_CHANGE * 9990 / 100, 1, 1, vCoins, setCoinsRet, nValueRet));
+        BOOST_CHECK(wallet.SelectCoinsMinConf(MIN_CHANGE * 9990 / 100, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
         BOOST_CHECK_EQUAL(nValueRet, 101 * MIN_CHANGE);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
@@ -269,7 +269,7 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
              // Create 676 inputs (= MAX_STANDARD_TX_SIZE / 148 bytes per input)
              for (uint16_t j = 0; j < 676; j++)
                  add_coin(amt);
-             BOOST_CHECK(wallet.SelectCoinsMinConf(2000, 1, 1, vCoins, setCoinsRet, nValueRet));
+             BOOST_CHECK(wallet.SelectCoinsMinConf(2000, 1, 1, 0, vCoins, setCoinsRet, nValueRet));
              if (amt - 2000 < MIN_CHANGE) {
                  // needs more than one input:
                  uint16_t returnSize = std::ceil((2000.0 + MIN_CHANGE)/amt);
@@ -291,8 +291,8 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
 
             // picking 50 from 100 coins doesn't depend on the shuffle,
             // but does depend on randomness in the stochastic approximation code
-            BOOST_CHECK(wallet.SelectCoinsMinConf(50 * COIN, 1, 6, vCoins, setCoinsRet , nValueRet));
-            BOOST_CHECK(wallet.SelectCoinsMinConf(50 * COIN, 1, 6, vCoins, setCoinsRet2, nValueRet));
+            BOOST_CHECK(wallet.SelectCoinsMinConf(50 * COIN, 1, 6, 0, vCoins, setCoinsRet , nValueRet));
+            BOOST_CHECK(wallet.SelectCoinsMinConf(50 * COIN, 1, 6, 0, vCoins, setCoinsRet2, nValueRet));
             BOOST_CHECK(!equal_sets(setCoinsRet, setCoinsRet2));
 
             int fails = 0;
@@ -300,8 +300,8 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
             {
                 // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
                 // run the test RANDOM_REPEATS times and only complain if all of them fail
-                BOOST_CHECK(wallet.SelectCoinsMinConf(COIN, 1, 6, vCoins, setCoinsRet , nValueRet));
-                BOOST_CHECK(wallet.SelectCoinsMinConf(COIN, 1, 6, vCoins, setCoinsRet2, nValueRet));
+                BOOST_CHECK(wallet.SelectCoinsMinConf(COIN, 1, 6, 0, vCoins, setCoinsRet , nValueRet));
+                BOOST_CHECK(wallet.SelectCoinsMinConf(COIN, 1, 6, 0, vCoins, setCoinsRet2, nValueRet));
                 if (equal_sets(setCoinsRet, setCoinsRet2))
                     fails++;
             }
@@ -321,8 +321,8 @@ BOOST_AUTO_TEST_CASE(coin_selection_tests)
             {
                 // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
                 // run the test RANDOM_REPEATS times and only complain if all of them fail
-                BOOST_CHECK(wallet.SelectCoinsMinConf(90*CENT, 1, 6, vCoins, setCoinsRet , nValueRet));
-                BOOST_CHECK(wallet.SelectCoinsMinConf(90*CENT, 1, 6, vCoins, setCoinsRet2, nValueRet));
+                BOOST_CHECK(wallet.SelectCoinsMinConf(90*CENT, 1, 6, 0, vCoins, setCoinsRet , nValueRet));
+                BOOST_CHECK(wallet.SelectCoinsMinConf(90*CENT, 1, 6, 0, vCoins, setCoinsRet2, nValueRet));
                 if (equal_sets(setCoinsRet, setCoinsRet2))
                     fails++;
             }
@@ -346,7 +346,7 @@ BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
         add_coin(1000 * COIN);
     add_coin(3 * COIN);
 
-    BOOST_CHECK(wallet.SelectCoinsMinConf(1003 * COIN, 1, 6, vCoins, setCoinsRet, nValueRet));
+    BOOST_CHECK(wallet.SelectCoinsMinConf(1003 * COIN, 1, 6, 0, vCoins, setCoinsRet, nValueRet));
     BOOST_CHECK_EQUAL(nValueRet, 1003 * COIN);
     BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 }
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 7f62402625..1a33744ce9 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1921,7 +1921,7 @@ static void ApproximateBestSubset(vector<pair<CAmount, pair<const CWalletTx*,uns
     }
 }
 
-bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, int nConfMine, int nConfTheirs, vector<COutput> vCoins,
+bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const int nConfMine, const int nConfTheirs, const uint64_t nMaxAncestors, vector<COutput> vCoins,
                                  set<pair<const CWalletTx*,unsigned int> >& setCoinsRet, CAmount& nValueRet) const
 {
     setCoinsRet.clear();
@@ -1946,6 +1946,9 @@ bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, int nConfMine, int
         if (output.nDepth < (pcoin->IsFromMe(ISMINE_ALL) ? nConfMine : nConfTheirs))
             continue;
 
+        if (!mempool.TransactionWithinChainLimit(pcoin->GetHash(), nMaxAncestors))
+            continue;
+
         int i = output.i;
         CAmount n = pcoin->vout[i].nValue;
 
@@ -2071,10 +2074,17 @@ bool CWallet::SelectCoins(const vector<COutput>& vAvailableCoins, const CAmount&
             ++it;
     }
 
+    size_t nMaxChainLength = std::min(GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT), GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT));
+    bool fRejectLongChains = GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS);
+
     bool res = nTargetValue <= nValueFromPresetInputs ||
-        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 1, 6, vCoins, setCoinsRet, nValueRet) ||
-        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 1, 1, vCoins, setCoinsRet, nValueRet) ||
-        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, vCoins, setCoinsRet, nValueRet));
+        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 1, 6, 0, vCoins, setCoinsRet, nValueRet) ||
+        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 1, 1, 0, vCoins, setCoinsRet, nValueRet) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, 2, vCoins, setCoinsRet, nValueRet)) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, std::min((size_t)4, nMaxChainLength/3), vCoins, setCoinsRet, nValueRet)) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, nMaxChainLength/2, vCoins, setCoinsRet, nValueRet)) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, nMaxChainLength, vCoins, setCoinsRet, nValueRet)) ||
+        (bSpendZeroConfChange && !fRejectLongChains && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, std::numeric_limits<uint64_t>::max(), vCoins, setCoinsRet, nValueRet));
 
     // because SelectCoinsMinConf clears the setCoinsRet, we now add the possible inputs to the coinset
     setCoinsRet.insert(setPresetCoins.begin(), setPresetCoins.end());
@@ -3263,6 +3273,7 @@ std::string CWallet::GetWalletHelpString(bool showDebug)
         strUsage += HelpMessageOpt("-dblogsize=<n>", strprintf("Flush wallet database activity from memory to disk log every <n> megabytes (default: %u)", DEFAULT_WALLET_DBLOGSIZE));
         strUsage += HelpMessageOpt("-flushwallet", strprintf("Run a thread to flush wallet periodically (default: %u)", DEFAULT_FLUSHWALLET));
         strUsage += HelpMessageOpt("-privdb", strprintf("Sets the DB_PRIVATE flag in the wallet db environment (default: %u)", DEFAULT_WALLET_PRIVDB));
+        strUsage += HelpMessageOpt("-walletrejectlongchains", strprintf(_("Wallet will not create transactions that violate mempool chain limits (default: %u"), DEFAULT_WALLET_REJECT_LONG_CHAINS));
     }
 
     return strUsage;
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 056dcc5daf..10f6ea8fed 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -51,6 +51,8 @@ static const CAmount MIN_CHANGE = CENT;
 static const bool DEFAULT_SPEND_ZEROCONF_CHANGE = true;
 //! Default for -sendfreetransactions
 static const bool DEFAULT_SEND_FREE_TRANSACTIONS = false;
+//! Default for -walletrejectlongchains
+static const bool DEFAULT_WALLET_REJECT_LONG_CHAINS = false;
 //! -txconfirmtarget default
 static const unsigned int DEFAULT_TX_CONFIRM_TARGET = 2;
 //! Largest (in bytes) free transaction we're willing to create
@@ -668,7 +670,7 @@ public:
      * completion the coin set and corresponding actual target value is
      * assembled
      */
-    bool SelectCoinsMinConf(const CAmount& nTargetValue, int nConfMine, int nConfTheirs, std::vector<COutput> vCoins, std::set<std::pair<const CWalletTx*,unsigned int> >& setCoinsRet, CAmount& nValueRet) const;
+    bool SelectCoinsMinConf(const CAmount& nTargetValue, int nConfMine, int nConfTheirs, uint64_t nMaxAncestors, std::vector<COutput> vCoins, std::set<std::pair<const CWalletTx*,unsigned int> >& setCoinsRet, CAmount& nValueRet) const;
 
     bool IsSpent(const uint256& hash, unsigned int n) const;