--- a/hotspot/src/share/vm/oops/instanceKlass.hpp	Wed Sep 16 15:42:46 2009 -0400
+++ b/hotspot/src/share/vm/oops/instanceKlass.hpp	Mon Sep 21 09:30:24 2009 -0600
@@ -465,6 +465,10 @@
   // RedefineClasses() support for previous versions:
   void add_previous_version(instanceKlassHandle ikh, BitMap *emcp_methods,
          int emcp_method_count);
+  // If the _previous_versions array is non-NULL, then this klass
+  // has been redefined at least once even if we aren't currently
+  // tracking a previous version.
+  bool has_been_redefined() const { return _previous_versions != NULL; }
   bool has_previous_version() const;
   void init_previous_versions() {
     _previous_versions = NULL;
@@ -506,9 +510,14 @@
   void set_bootstrap_method(oop mh)                   { oop_store(&_bootstrap_method, mh); }
 
   // jmethodID support
-  static jmethodID get_jmethod_id(instanceKlassHandle ik_h, size_t idnum,
-                                  jmethodID new_id, jmethodID* new_jmeths);
-  static jmethodID jmethod_id_for_impl(instanceKlassHandle ik_h, methodHandle method_h);
+  static jmethodID get_jmethod_id(instanceKlassHandle ik_h,
+                     methodHandle method_h);
+  static jmethodID get_jmethod_id_fetch_or_update(instanceKlassHandle ik_h,
+                     size_t idnum, jmethodID new_id, jmethodID* new_jmeths,
+                     jmethodID* to_dealloc_id_p,
+                     jmethodID** to_dealloc_jmeths_p);
+  static void get_jmethod_id_length_value(jmethodID* cache, size_t idnum,
+                size_t *length_p, jmethodID* id_p);
   jmethodID jmethod_id_or_null(methodOop method);
 
   // cached itable index support
@@ -754,6 +763,11 @@
   void set_init_thread(Thread *thread)  { _init_thread = thread; }
 
   u2 idnum_allocated_count() const      { return _idnum_allocated_count; }
+  // The RedefineClasses() API can cause new method idnums to be needed
+  // which will cause the caches to grow. Safety requires different
+  // cache management logic if the caches can grow instead of just
+  // going from NULL to non-NULL.
+  bool idnum_can_increment() const      { return has_been_redefined(); }
   jmethodID* methods_jmethod_ids_acquire() const
          { return (jmethodID*)OrderAccess::load_ptr_acquire(&_methods_jmethod_ids); }
   void release_set_methods_jmethod_ids(jmethodID* jmeths)