Scan and remove old entries in addMutations

Bench.cpp

@@ -7,6 +7,8 @@ void monotonicallyIncreasing() {
   ankerl::nanobench::Bench bench;
   Facade facade{0};
 
+  bench.minEpochIterations(1000);
+
   bench.warmup(kWindow).run("monotonically increasing", [&] {
     const int64_t remove = __builtin_bswap64(facade.getVersion() - kWindow);
     const int64_t next = __builtin_bswap64(facade.getVersion());
@@ -18,6 +20,8 @@ void monotonicallyIncreasing() {
     };
     facade.addMutations(mutations, sizeof(mutations) / sizeof(mutations[0]),
                         facade.getVersion() + 1);
+    facade.setOldestVersion(
+        std::max<int64_t>(0, facade.getVersion() - kWindow));
   });
 
   const auto v = facade.getVersion() - kWindow / 2;
@@ -25,7 +29,6 @@ void monotonicallyIncreasing() {
   const auto end = facade.versioned.end(v);
   auto iter = begin;
 
-  // Slow because all the clears from old versions are still around.
   bench.run("scan", [&] {
     for (iter = begin; iter != end; ++iter) {
     }