From 76d2f068a4cbd2bfe50c166fe0babfc5f17acaf4 Mon Sep 17 00:00:00 2001
From: Andrew Chow <achow101-github@achow101.com>
Date: Tue, 6 Mar 2018 14:24:15 -0500
Subject: [PATCH] Benchmark BnB in the worst case where it exhausts

---
 src/bench/coin_selection.cpp | 44 ++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/src/bench/coin_selection.cpp b/src/bench/coin_selection.cpp
index 605d9e3e66..4b2a0e72fe 100644
--- a/src/bench/coin_selection.cpp
+++ b/src/bench/coin_selection.cpp
@@ -4,6 +4,7 @@
 
 #include <bench/bench.h>
 #include <wallet/wallet.h>
+#include <wallet/coinselection.h>
 
 #include <set>
 
@@ -61,4 +62,47 @@ static void CoinSelection(benchmark::State& state)
     }
 }
 
+typedef std::set<CInputCoin> CoinSet;
+
+// Copied from src/wallet/test/coinselector_tests.cpp
+static void add_coin(const CAmount& nValue, int nInput, std::vector<CInputCoin>& set)
+{
+    CMutableTransaction tx;
+    tx.vout.resize(nInput + 1);
+    tx.vout[nInput].nValue = nValue;
+    set.emplace_back(MakeTransactionRef(tx), nInput);
+}
+// Copied from src/wallet/test/coinselector_tests.cpp
+static CAmount make_hard_case(int utxos, std::vector<CInputCoin>& utxo_pool)
+{
+    utxo_pool.clear();
+    CAmount target = 0;
+    for (int i = 0; i < utxos; ++i) {
+        target += (CAmount)1 << (utxos+i);
+        add_coin((CAmount)1 << (utxos+i), 2*i, utxo_pool);
+        add_coin(((CAmount)1 << (utxos+i)) + ((CAmount)1 << (utxos-1-i)), 2*i + 1, utxo_pool);
+    }
+    return target;
+}
+
+static void BnBExhaustion(benchmark::State& state)
+{
+    // Setup
+    std::vector<CInputCoin> utxo_pool;
+    CoinSet selection;
+    CAmount value_ret = 0;
+    CAmount not_input_fees = 0;
+
+    while (state.KeepRunning()) {
+        // Benchmark
+        CAmount target = make_hard_case(17, utxo_pool);
+        SelectCoinsBnB(utxo_pool, target, 0, selection, value_ret, not_input_fees); // Should exhaust
+
+        // Cleanup
+        utxo_pool.clear();
+        selection.clear();
+    }
+}
+
 BENCHMARK(CoinSelection, 650);
+BENCHMARK(BnBExhaustion, 650);