[Gnash-commit] /srv/bzr/gnash/trunk r11698: Change default THREASHOLD from 50 to 64 (nicer number).

[Sandro Santilli]

------------------------------------------------------------
revno: 11698
committer: Sandro Santilli <address@hidden>
branch nick: trunk
timestamp: Wed 2009-12-16 00:54:32 +0100
message:
  Change default THREASHOLD from 50 to 64 (nicer number).
  Cleanup debugging prints so it gives better informations for stats.
  Add some documentation in the ::collect method as a starting point to try at 
improving the heuristic used to skip collection cycles.
  Use typeName rather than typeid.
modified:
  libbase/GC.cpp
  libbase/GC.h

=== modified file 'libbase/GC.cpp'
--- a/libbase/GC.cpp    2009-12-15 22:49:29 +0000
+++ b/libbase/GC.cpp    2009-12-15 23:54:32 +0000
@@ -33,7 +33,7 @@
 namespace gnash {
 
 GC* GC::_singleton = NULL;
-unsigned int GC::maxNewCollectablesCount = 50;
+unsigned int GC::maxNewCollectablesCount = 64;
 
 GC&
 GC::init(GcRoot& root)
@@ -67,7 +67,7 @@
 GC::~GC()
 {
 #ifdef GNASH_GC_DEBUG 
-       log_debug(_("GC %p deleted, deleting all managed resources - collector 
run %d times"), (void*)this, _collectorRuns);
+       log_debug(_("GC deleted, deleting all managed resources - collector run 
%d times"), _collectorRuns);
 #endif
 
 #if 1
@@ -84,7 +84,7 @@
        size_t deleted = 0;
 
 #if (GNASH_GC_DEBUG > 1)
-       log_debug(_("GC %p: SWEEP SCAN"), (void*)this);
+       log_debug(_("GC: sweep scan started"));
 #endif
 
        for (ResList::iterator i=_resList.begin(), e=_resList.end(); i!=e; )
@@ -93,8 +93,8 @@
                if ( ! res->isReachable() )
                {
 #if GNASH_GC_DEBUG > 1
-                       log_debug(_("GC %p: cleanUnreachable deleting object %p 
(%s)"),
-                                       (void*)this, (void*)res, 
typeName(*res).c_str());
+                       log_debug(_("GC: recycling object %p (%s)"),
+                                       res, typeName(*res).c_str());
 #endif
                        ++deleted;
                        delete res;
@@ -113,22 +113,54 @@
 void 
 GC::collect()
 {
-       size_t curResSize = _resList.size(); // this is O(n) on GNU stdc++ lib !
-       if ( curResSize <  _lastResCount + maxNewCollectablesCount )
+       // Heuristic to decide wheter or not to run the collection cycle
+       //
+       //
+       // Things to consider:
+       //
+       //  - Cost 
+       //      - Depends on the number of reachable collectables
+       //      - Depends on the frequency of runs
+       //
+       //  - Advantages 
+       //      - Depends on the number of unreachable collectables
+       //
+       //  - Cheaply computable informations
+       //      - Number of collectables (currently O(n) but can be optimized)
+       //      - Total heap-allocated memory (currently unavailable)
+       //
+       // Current heuristic:
+       //
+       //  - We run the cycle again if X new collectables were allocated
+       //    since last cycle run. X defaults to maxNewCollectablesCount
+       //    and can be changed by user (GNASH_GC_TRIGGER_THRESHOLD env
+       //    variable).
+       //
+       // Possible improvements:
+       //
+       //  - Adapt X (maxNewCollectablesCount) based on cost/advantage
+       //    runtime analisys
+       //
+
+       size_t curResCount = _resList.size(); // this is O(n) on GNU stdc++ lib 
!
+       if ( curResCount <  _lastResCount + maxNewCollectablesCount )
        {
 #if GNASH_GC_DEBUG  > 1
-               log_debug(_("Garbage collection skipped since number of 
collectables added since last run is too low (%d)"),
-                              curResSize - _lastResCount);
+               log_debug(_("GC: collection cycle skipped - %d/%d new resources 
allocated since last run (from %d to %d)"), curResCount-_lastResCount, 
maxNewCollectablesCount, _lastResCount, curResCount);
 #endif // GNASH_GC_DEBUG
                return;
        }
 
+       //
+       // Collection cycle
+       //
+
 #ifdef GNASH_GC_DEBUG 
        ++_collectorRuns;
 #endif
 
 #ifdef GNASH_GC_DEBUG 
-       log_debug(_("GC %p Starting collector: %d collectables (from %d of last 
run)"), (void *)this, curResSize, _lastResCount);
+       log_debug(_("GC: collection cycle started - %d/%d new resources 
allocated since last run (from %d to %d)"), curResCount-_lastResCount, 
maxNewCollectablesCount, _lastResCount, curResCount);
 #endif // GNASH_GC_DEBUG
 
 #ifndef NDEBUG
@@ -142,15 +174,15 @@
        // clean unreachable resources, and mark the others as reachable again
        size_t deleted = cleanUnreachable();
 
-       _lastResCount = curResSize - deleted;
+       _lastResCount = curResCount - deleted;
 
 #ifdef GNASH_GC_DEBUG 
-       log_debug(_("GC %p: cleanUnreachable deleted %d unreachable resources, "
-            "leaving %d alive"),
-                       (void*)this, deleted, _lastResCount);
-       assert(_lastResCount == _resList.size()); // again O(n)...
+       log_debug(_("GC: recycled %d unreachable resources - %d left"),
+                       deleted, _lastResCount);
 #endif
 
+       //assert(_lastResCount == _resList.size()); // again O(n)...
+
 }
 
 void

=== modified file 'libbase/GC.h'
--- a/libbase/GC.h      2009-06-07 22:10:39 +0000
+++ b/libbase/GC.h      2009-12-15 23:54:32 +0000
@@ -45,6 +45,7 @@
 
 #ifdef GNASH_GC_DEBUG
 # include "log.h"
+# include "utility.h"
 # include <typeinfo>
 #endif
 
@@ -112,7 +113,7 @@
                {
 #if GNASH_GC_DEBUG > 2
                        log_debug(_("Instance %p of class %s already reachable, 
setReachable doing nothing"),
-                                       (void*)this, typeid(*this).name());
+                                       (void*)this, typeName(*this));
 #endif
                        return;
                }