fix ringbuffer size decrease

diff --git a/pdns/statbag.cc b/pdns/statbag.cc
index 83421ff75f6217f7cb39576dfc4401e9ee0dca95..430c04829959e86e2dcd5277dce7ff90ba91c227 100644 (file)
--- a/pdns/statbag.cc
+++ b/pdns/statbag.cc
@@ -189,26 +189,28 @@ void StatRing::resize(unsigned int newsize)
     return;
   Lock l(d_lock);
 
-  if(newsize>d_size) {
-    d_size=newsize;
-    d_items.resize(d_size);
-    return;
-  }
-
   // this is the hard part, shrink
-  int startpos=d_pos-newsize;
-  int rpos;
-  vector<string>newring;
-  for(unsigned int i=startpos;i<d_pos;++i) {
-    rpos= i;
+  if(newsize<d_size) {
+    unsigned int startpos=0;
+    if (d_pos>newsize)
+      startpos=d_pos-newsize;
+
+    vector<string>newring;
+    for(unsigned int i=startpos;i<d_pos;++i) {
+      newring.push_back(d_items[i%d_size]);
+    }
 
-    newring.push_back(d_items[rpos%d_size]);
+    d_items=newring;
+    d_size=newring.size();
+    d_pos=min(d_pos,newsize);
   }
-  d_items=newring;
-  d_size=newsize;
-  d_pos=d_size-1;
 
+  if(newsize>d_size) {
+    d_size=newsize;
+    d_items.resize(d_size);
+  }
 }
+
 StatRing::~StatRing()
 {
   // do not clean up d_lock, it is shared