From 6a07c2282673562f67d12d31cd618be85d80f45a Mon Sep 17 00:00:00 2001
From: James Turner <zakalawe@mac.com>
Date: Sat, 7 Aug 2010 10:25:20 +0100
Subject: [PATCH] Catch subsystem update() exceptions in the manager, and
 permit a maximum number of exceptions before suspending the subsystem.

---
 simgear/structure/subsystem_mgr.cxx | 30 ++++++++++++++++++++++-------
 simgear/structure/subsystem_mgr.hxx |  1 +
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/simgear/structure/subsystem_mgr.cxx b/simgear/structure/subsystem_mgr.cxx
index 26f026cd..9488faea 100644
--- a/simgear/structure/subsystem_mgr.cxx
+++ b/simgear/structure/subsystem_mgr.cxx
@@ -8,7 +8,7 @@
 #include <simgear/math/SGMath.hxx>
 
 
-
+const int SG_MAX_SUBSYSTEM_EXCEPTIONS = 4;
 ////////////////////////////////////////////////////////////////////////
 // Implementation of SGSubsystem
 ////////////////////////////////////////////////////////////////////////
@@ -308,7 +308,8 @@ SGSubsystemGroup::Member::Member ()
       subsystem(0),
       min_step_sec(0),
       elapsed_sec(0),
-      collectTimeStats(false)
+      collectTimeStats(false),
+      exceptionCount(0)
 {
 }
 
@@ -326,11 +327,26 @@ void
 SGSubsystemGroup::Member::update (double delta_time_sec)
 {
     elapsed_sec += delta_time_sec;
-    if (elapsed_sec >= min_step_sec) {
-        if (!subsystem->is_suspended()) {
-            subsystem->update(elapsed_sec);
-            elapsed_sec = 0;
-        }
+    if (elapsed_sec < min_step_sec) {
+        return;
+    }
+    
+    if (subsystem->is_suspended()) {
+        return;
+    }
+    
+    try {
+      subsystem->update(elapsed_sec);
+      elapsed_sec = 0;
+    } catch (sg_exception& e) {
+      SG_LOG(SG_GENERAL, SG_ALERT, "caught exception processing subsystem:" << name
+        << "\nmessage:" << e.getMessage());
+      
+      if (++exceptionCount > SG_MAX_SUBSYSTEM_EXCEPTIONS) {
+        SG_LOG(SG_GENERAL, SG_ALERT, "(exceptionCount=" << exceptionCount <<
+          ", suspending)");
+        subsystem->suspend();
+      }
     }
 }
 
diff --git a/simgear/structure/subsystem_mgr.hxx b/simgear/structure/subsystem_mgr.hxx
index 02332056..5b449cca 100644
--- a/simgear/structure/subsystem_mgr.hxx
+++ b/simgear/structure/subsystem_mgr.hxx
@@ -344,6 +344,7 @@ private:
         double min_step_sec;
         double elapsed_sec;
         bool collectTimeStats;
+        int exceptionCount;
     };
 
     Member * get_member (const string &name, bool create = false);
-- 
2.39.5