Bug 392873. Add debugging code to help track down a crash in the bfcache-expiry code. r+sr=bzbarsky,a=damon

git-svn-id: svn://10.0.0.236/trunk@236961 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/docshell/shistory/src/nsSHEntry.cpp

@@ -160,6 +160,14 @@ nsSHEntry::~nsSHEntry()
   if (viewer) {
     viewer->Destroy();
   }
+
+#ifdef DEBUG
+  nsExpirationTracker<nsSHEntry,3>::Iterator iterator(gHistoryTracker);
+  nsSHEntry* elem;
+  while ((elem = iterator.Next()) != nsnull) {
+    NS_ASSERTION(elem != this, "Found dead entry still in the tracker!");
+  }
+#endif
 }
 
 //*****************************************************************************

mozilla/xpcom/ds/nsExpirationTracker.h

@@ -234,6 +234,29 @@ template <class T, PRUint32 K> class nsExpirationTracker {
         AgeOneGeneration();
       }
     }
+    
+    class Iterator {
+    private:
+      nsExpirationTracker<T,K>* mTracker;
+      PRUint32                  mGeneration;
+      PRUint32                  mIndex;
+    public:
+      Iterator(nsExpirationTracker<T,K>* aTracker)
+        : mTracker(aTracker), mGeneration(0), mIndex(0) {}
+      T* Next() {
+        while (mGeneration < K) {
+          nsTArray<T*>* generation = &mTracker->mGenerations[mGeneration];
+          if (mIndex < generation->Length()) {
+            ++mIndex;
+            return (*generation)[mIndex - 1];
+          }
+          ++mGeneration;
+        }
+        return nsnull;
+      }
+    };
+    
+    friend class Iterator;
 
   protected:
     /**