avoid some locking functions

Summary: This is a behavior-preserving change.

Reviewed By: thezhangwei

Differential Revision: D50439284

fbshipit-source-id: 0562ce35459fc959fe68bd7771becd13f9943c1f

libredex/ConcurrentContainers.h

@@ -1180,6 +1180,13 @@ class ConcurrentMap final
     return ptr->second;
   }
 
+  Value get_unsafe(const Key& key, Value default_value) const {
+    size_t slot = Hash()(key) % n_slots;
+    const auto& map = this->get_container(slot);
+    const auto* ptr = map.get(key);
+    return ptr ? ptr->second : default_value;
+  }
+
   /*
    * The Boolean return value denotes whether the insertion took place.
    * This operation is always thread-safe.

libredex/Reachability.cpp

@@ -2392,7 +2392,7 @@ void dump_graph(std::ostream& os, const ReachableObjectGraph& retainers_of) {
         if (!retainers_of.count(obj)) {
           return {};
         }
-        const auto& preds = retainers_of.at(obj);
+        const auto& preds = retainers_of.at_unsafe(obj);
         std::vector<ReachableObject> preds_vec(preds.begin(), preds.end());
         // Gotta sort the reachables or the output is nondeterministic.
         std::sort(preds_vec.begin(), preds_vec.end(), compare);

opt/optimize_enums/OptimizeEnums.cpp

@@ -499,8 +499,9 @@ class OptimizeEnums {
                      [](const auto& p) { return p.first; });
       std::sort(unsafe_types.begin(), unsafe_types.end(), compare_dextypes);
       for (auto* t : unsafe_types) {
-        ofs << show(t) << ":" << unsafe_enums.at(t) << "\n";
-        for (auto u : unsafe_enums.at(t)) {
+        const auto& unsafe_enums_at_t = unsafe_enums.at_unsafe(t);
+        ofs << show(t) << ":" << unsafe_enums_at_t << "\n";
+        for (auto u : unsafe_enums_at_t) {
           ++unsafe_counts[u];
         }
       }

opt/virtual_merging/VirtualMerging.cpp

@@ -667,7 +667,7 @@ VirtualMerging::compute_mergeable_pairs_by_virtual_scopes(
   walk::parallel::virtual_scopes(
       virtual_scopes, [&](const virt_scope::VirtualScope* virtual_scope) {
         MergePairsBuilder mpb(virtual_scope, ordering_provider, m_perf_config);
-        auto res = mpb.build(m_mergeable_scope_methods.at(virtual_scope),
+        auto res = mpb.build(m_mergeable_scope_methods.at_unsafe(virtual_scope),
                              m_xstores, m_xdexes, profiles, strategy);
         if (!res) {
           return;