From ef62affc6d31f42456673b04558460baffaa8dd2 Mon Sep 17 00:00:00 2001
From: Gareth Rees <gdr@ravenbrook.com>
Date: Thu, 3 Sep 2015 15:35:38 +0100
Subject: [PATCH] Move the clearing of the emergency flag down into
 tracedestroy{init,finish}.

Copied from Perforce
 Change: 188216
 ServerID: perforce.ravenbrook.com
---
 mps/code/policy.c   |  3 ---
 mps/code/trace.c    | 15 +++++++--------
 mps/code/traceanc.c |  7 +++----
 3 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/mps/code/policy.c b/mps/code/policy.c
index ff570e4899b..3cba467a2c7 100644
--- a/mps/code/policy.c
+++ b/mps/code/policy.c
@@ -259,9 +259,6 @@ Bool PolicyStartTrace(Trace *traceReturn, Arena arena)
 
 failCondemn:
   TraceDestroyInit(trace);
-  /* This is an unlikely case, but clear the emergency flag so the next attempt
-     starts normally. */
-  ArenaSetEmergency(arena, FALSE);
 failStart:
   return FALSE;
 }
diff --git a/mps/code/trace.c b/mps/code/trace.c
index d34d953bf40..5786c677a51 100644
--- a/mps/code/trace.c
+++ b/mps/code/trace.c
@@ -771,6 +771,9 @@ void TraceDestroyInit(Trace trace)
 
   trace->sig = SigInvalid;
   trace->arena->busyTraces = TraceSetDel(trace->arena->busyTraces, trace);
+
+  /* Clear the emergency flag so the next trace starts normally. */
+  ArenaSetEmergency(trace->arena, FALSE);
 }
 
 
@@ -828,6 +831,9 @@ void TraceDestroyFinished(Trace trace)
   trace->sig = SigInvalid;
   trace->arena->busyTraces = TraceSetDel(trace->arena->busyTraces, trace);
   trace->arena->flippedTraces = TraceSetDel(trace->arena->flippedTraces, trace);
+
+  /* Hopefully the trace reclaimed some memory, so clear any emergency. */
+  ArenaSetEmergency(trace->arena, FALSE);
 }
 
 
@@ -1833,9 +1839,6 @@ failStart:
   NOTREACHED;
 failCondemn:
   TraceDestroyInit(trace);
-  /* We don't know how long it'll be before another collection.  Make sure
-     the next one starts in normal mode. */
-  ArenaSetEmergency(arena, FALSE);
   return res;
 }
 
@@ -1873,12 +1876,8 @@ Work TracePoll(Globals globals)
   newWork = traceWork(trace);
   AVER(newWork >= oldWork);
   work = newWork - oldWork;
-  if (trace->state == TraceFINISHED) {
+  if (trace->state == TraceFINISHED)
     TraceDestroyFinished(trace);
-    /* A trace finished, and hopefully reclaimed some memory, so clear any
-     * emergency. */
-    ArenaSetEmergency(arena, FALSE);
-  }
   return work;
 }
 
diff --git a/mps/code/traceanc.c b/mps/code/traceanc.c
index c3743b6dc29..e60f8ffcdb3 100644
--- a/mps/code/traceanc.c
+++ b/mps/code/traceanc.c
@@ -591,10 +591,9 @@ void ArenaPark(Globals globals)
   }
 
   ArenaAccumulateTime(arena, start);
-  
-  /* Clear any emergency flag so that the next collection starts normally.
-     Any traces that have been finished may have reclaimed memory. */
-  ArenaSetEmergency(arena, FALSE);
+
+  /* All traces have finished so there must not be an emergency. */
+  AVER(!ArenaEmergency(arena));
 }
 
 /* ArenaStartCollect -- start a collection of everything in the