src/hotspot/share/runtime/objectMonitor.hpp

rev 54415 : 8222295: more baseline cleanups from Async Monitor Deflation project

@@ -161,13 +161,13 @@
   Thread * volatile _Responsible;
 
   volatile int _Spinner;            // for exit->spinner handoff optimization
   volatile int _SpinDuration;
 
-  volatile jint  _count;            // reference count to prevent reclamation/deflation
-                                    // at stop-the-world time. See ObjectSynchronizer::deflate_monitor().
-                                    // _count is approximately |_WaitSet| + |_EntryList|
+  volatile jint  _contentions;      // Number of active contentions in enter(). It is used by is_busy()
+                                    // along with other fields to determine if an ObjectMonitor can be
+                                    // deflated. See ObjectSynchronizer::deflate_monitor().
  protected:
   ObjectWaiter * volatile _WaitSet; // LL of threads wait()ing on the monitor
   volatile jint  _waiters;          // number of waiting threads
  private:
   volatile int _WaitSetLock;        // protects Wait Queue - simple spinlock

@@ -205,11 +205,10 @@
   // TODO-FIXME: the "offset" routines should return a type of off_t instead of int ...
   // ByteSize would also be an appropriate type.
   static int header_offset_in_bytes()      { return offset_of(ObjectMonitor, _header); }
   static int object_offset_in_bytes()      { return offset_of(ObjectMonitor, _object); }
   static int owner_offset_in_bytes()       { return offset_of(ObjectMonitor, _owner); }
-  static int count_offset_in_bytes()       { return offset_of(ObjectMonitor, _count); }
   static int recursions_offset_in_bytes()  { return offset_of(ObjectMonitor, _recursions); }
   static int cxq_offset_in_bytes()         { return offset_of(ObjectMonitor, _cxq); }
   static int succ_offset_in_bytes()        { return offset_of(ObjectMonitor, _succ); }
   static int EntryList_offset_in_bytes()   { return offset_of(ObjectMonitor, _EntryList); }
 

@@ -230,25 +229,21 @@
   markOop   header() const;
   volatile markOop* header_addr();
   void      set_header(markOop hdr);
 
   intptr_t is_busy() const {
-    // TODO-FIXME: merge _count and _waiters.
     // TODO-FIXME: assert _owner == null implies _recursions = 0
-    // TODO-FIXME: assert _WaitSet != null implies _count > 0
-    return _count|_waiters|intptr_t(_owner)|intptr_t(_cxq)|intptr_t(_EntryList);
+    return _contentions|_waiters|intptr_t(_owner)|intptr_t(_cxq)|intptr_t(_EntryList);
   }
 
   intptr_t  is_entered(Thread* current) const;
 
   void*     owner() const;
   void      set_owner(void* owner);
 
   jint      waiters() const;
 
-  jint      count() const;
-  void      set_count(jint count);
   jint      contentions() const;
   intptr_t  recursions() const                                         { return _recursions; }
 
   // JVM/TI GetObjectMonitorUsage() needs this:
   ObjectWaiter* first_waiter()                                         { return _WaitSet; }

@@ -261,18 +256,18 @@
   ObjectMonitor() { ::memset((void *)this, 0, sizeof(*this)); }
 
   ~ObjectMonitor() {
     // TODO: Add asserts ...
     // _cxq == 0 _succ == NULL _owner == NULL _waiters == 0
-    // _count == 0 _EntryList  == NULL etc
+    // _contentions == 0 _EntryList  == NULL etc
   }
 
  private:
   void Recycle() {
     // TODO: add stronger asserts ...
     // _cxq == 0 _succ == NULL _owner == NULL _waiters == 0
-    // _count == 0 EntryList  == NULL
+    // _contentions == 0 EntryList  == NULL
     // _recursions == 0 _WaitSet == NULL
     assert(((is_busy()|_recursions) == 0), "freeing inuse monitor");
     _succ          = NULL;
     _EntryList     = NULL;
     _cxq           = NULL;