From 1d0c81dea4bb6bcf68c2e4776eefbecabc9b9ab3 Mon Sep 17 00:00:00 2001
From: Peter Barnes <barnes26@llnl.gov>
Date: Mon, 20 Dec 2021 21:59:44 +0000
Subject: [PATCH] core: pre-event hook, to facilitate chaining SimulatorImpls

---
 src/core/model/default-simulator-impl.cc     | 8 ++++----
 src/core/model/default-simulator-impl.h      | 7 +++----
 src/core/model/realtime-simulator-impl.cc    | 4 ++++
 src/core/model/simulator-impl.h              | 7 +++++++
 src/mpi/model/distributed-simulator-impl.cc  | 3 +++
 src/mpi/model/null-message-simulator-impl.cc | 3 +++
 6 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/src/core/model/default-simulator-impl.cc b/src/core/model/default-simulator-impl.cc
index 2bb94d56a..c342c89e2 100644
--- a/src/core/model/default-simulator-impl.cc
+++ b/src/core/model/default-simulator-impl.cc
@@ -20,11 +20,8 @@
 
 #include "simulator.h"
 #include "default-simulator-impl.h"
-#include "scheduler.h"
-#include "event-impl.h"
 
-#include "ptr.h"
-#include "pointer.h"
+#include "scheduler.h"
 #include "assert.h"
 #include "log.h"
 
@@ -135,6 +132,9 @@ DefaultSimulatorImpl::ProcessOneEvent (void)
 {
   Scheduler::Event next = m_events->RemoveNext ();
 
+  PreEventHook (EventId (next.impl, next.key.m_ts, 
+                         next.key.m_context, next.key.m_uid));
+
   NS_ASSERT (next.key.m_ts >= m_currentTs);
   m_unscheduledEvents--;
   m_eventCount++;
diff --git a/src/core/model/default-simulator-impl.h b/src/core/model/default-simulator-impl.h
index d05284e69..473dac89b 100644
--- a/src/core/model/default-simulator-impl.h
+++ b/src/core/model/default-simulator-impl.h
@@ -22,13 +22,9 @@
 #define DEFAULT_SIMULATOR_IMPL_H
 
 #include "simulator-impl.h"
-#include "scheduler.h"
-#include "event-impl.h"
 #include "system-thread.h"
 #include "system-mutex.h"
 
-#include "ptr.h"
-
 #include <list>
 
 /**
@@ -39,6 +35,9 @@
 
 namespace ns3 {
 
+// Forward
+class Scheduler;
+
 /**
  * \ingroup simulator
  *
diff --git a/src/core/model/realtime-simulator-impl.cc b/src/core/model/realtime-simulator-impl.cc
index ab0f76912..e4bb08703 100644
--- a/src/core/model/realtime-simulator-impl.cc
+++ b/src/core/model/realtime-simulator-impl.cc
@@ -325,6 +325,10 @@ RealtimeSimulatorImpl::ProcessOneEvent (void)
     NS_ASSERT_MSG (m_events->IsEmpty () == false,
                    "RealtimeSimulatorImpl::ProcessOneEvent(): event queue is empty");
     next = m_events->RemoveNext ();
+
+    PreEventHook (EventId (next.impl, next.key.m_ts, 
+                           next.key.m_context, next.key.m_uid));
+
     m_unscheduledEvents--;
     m_eventCount++;
 
diff --git a/src/core/model/simulator-impl.h b/src/core/model/simulator-impl.h
index afde956bc..50f76a721 100644
--- a/src/core/model/simulator-impl.h
+++ b/src/core/model/simulator-impl.h
@@ -102,6 +102,13 @@ public:
   /** \copydoc Simulator::GetEventCount */
   virtual uint64_t GetEventCount (void) const = 0;
 
+  /** 
+   * Hook called before processing each event.
+   *
+   * \param [in] id The event about to be processed.
+   */
+  virtual void PreEventHook (const EventId & id) {};
+
 };
 
 } // namespace ns3
diff --git a/src/mpi/model/distributed-simulator-impl.cc b/src/mpi/model/distributed-simulator-impl.cc
index 91cda1957..b59700a87 100644
--- a/src/mpi/model/distributed-simulator-impl.cc
+++ b/src/mpi/model/distributed-simulator-impl.cc
@@ -309,6 +309,9 @@ DistributedSimulatorImpl::ProcessOneEvent (void)
 
   Scheduler::Event next = m_events->RemoveNext ();
 
+  PreEventHook (EventId (next.impl, next.key.m_ts, 
+                         next.key.m_context, next.key.m_uid));
+
   NS_ASSERT (next.key.m_ts >= m_currentTs);
   m_unscheduledEvents--;
   m_eventCount++;
diff --git a/src/mpi/model/null-message-simulator-impl.cc b/src/mpi/model/null-message-simulator-impl.cc
index 0d77baa5f..c4d2b1ab7 100644
--- a/src/mpi/model/null-message-simulator-impl.cc
+++ b/src/mpi/model/null-message-simulator-impl.cc
@@ -230,6 +230,9 @@ NullMessageSimulatorImpl::ProcessOneEvent (void)
 
   Scheduler::Event next = m_events->RemoveNext ();
 
+  PreEventHook (EventId (next.impl, next.key.m_ts, 
+                         next.key.m_context, next.key.m_uid));
+
   NS_ASSERT (next.key.m_ts >= m_currentTs);
   m_unscheduledEvents--;
   m_eventCount++;