Cache env and param pointers in InPlaceExecutionContext

Execute() called Simulation::GetActive()->GetEnvironment() and
GetParam() for every agent every step. These pointers are stable
within an agent-ops phase, so cache them once in SetupAgentOpsAll
and reuse the cached values in Execute. Eliminates two pointer
chases per agent per step.

Author: stanbot8

src/core/execution_context/in_place_exec_ctxt.cc

@@ -140,15 +140,26 @@ void InPlaceExecutionContext::TearDownIterationAll(
 }
 
 void InPlaceExecutionContext::SetupAgentOpsAll(
-    const std::vector<ExecutionContext*>& all_exec_ctxts) {}
+    const std::vector<ExecutionContext*>& all_exec_ctxts) {
+  auto* sim = Simulation::GetActive();
+  auto* env = sim->GetEnvironment();
+  auto* param = sim->GetParam();
+  for (auto* ec : all_exec_ctxts) {
+    auto* ctxt = bdm_static_cast<InPlaceExecutionContext*>(ec);
+    ctxt->cached_env_ = env;
+    ctxt->cached_param_ = param;
+  }
+}
 
 void InPlaceExecutionContext::TearDownAgentOpsAll(
     const std::vector<ExecutionContext*>& all_exec_ctxts) {}
 
 void InPlaceExecutionContext::Execute(
     Agent* agent, AgentHandle ah, const std::vector<Operation*>& operations) {
-  auto* env = Simulation::GetActive()->GetEnvironment();
-  auto* param = Simulation::GetActive()->GetParam();
+  auto* env =
+      cached_env_ ? cached_env_ : Simulation::GetActive()->GetEnvironment();
+  auto* param =
+      cached_param_ ? cached_param_ : Simulation::GetActive()->GetParam();
 
   if (param->thread_safety_mechanism ==
       Param::ThreadSafetyMechanism::kUserSpecified) {

src/core/execution_context/in_place_exec_ctxt.h

@@ -34,6 +34,9 @@
 
 namespace bdm {
 
+class Environment;
+struct Param;
+
 namespace in_place_exec_ctxt_detail {
 class InPlaceExecutionContext_NeighborCacheValidity_Test;
 }
@@ -157,6 +160,11 @@ class InPlaceExecutionContext : public ExecutionContext {
   /// Cache the value of Param::cache_neighbors
   bool cache_neighbors_ = false;
 
+  /// Cached pointers refreshed once per agent-ops phase in SetupAgentOpsAll,
+  /// so Execute avoids per-agent Simulation::GetActive() lookups.
+  Environment* cached_env_ = nullptr;
+  const Param* cached_param_ = nullptr;
+
   /// Check whether or not the neighbors in `neighbor_cache_` were queried with
   /// the same squared radius (`cached_squared_search_radius_`) as currently
   /// being queried with (`query_squared_radius_`)