src/hotspot/share/runtime/objectMonitor.inline.hpp

rev 54110 : Checkpoint latest preliminary review patches for full OpenJDK review.

*** 51,74 ****
  
  inline jint ObjectMonitor::waiters() const {
    return _waiters;
  }
  
  inline void* ObjectMonitor::owner() const {
!   return _owner;
  }
  
  inline void ObjectMonitor::clear() {
-   assert(_header != NULL, "Fatal logic error in ObjectMonitor header!");
    assert(_count == 0, "Fatal logic error in ObjectMonitor count!");
    assert(_waiters == 0, "Fatal logic error in ObjectMonitor waiters!");
    assert(_recursions == 0, "Fatal logic error in ObjectMonitor recursions!");
    assert(_object != NULL, "Fatal logic error in ObjectMonitor object!");
!   assert(_owner == NULL, "Fatal logic error in ObjectMonitor owner!");
  
    _header = NULL;
    _object = NULL;
  }
  
  inline void* ObjectMonitor::object() const {
    return _object;
  }
--- 51,94 ----
  
  inline jint ObjectMonitor::waiters() const {
    return _waiters;
  }
  
+ // Returns NULL if DEFLATER_MARKER is observed.
  inline void* ObjectMonitor::owner() const {
!   void* owner = _owner;
!   return owner != DEFLATER_MARKER ? owner : NULL;
  }
  
  inline void ObjectMonitor::clear() {
    assert(_count == 0, "Fatal logic error in ObjectMonitor count!");
+   assert(_owner == NULL, "Fatal logic error in ObjectMonitor owner!");
+ 
+   clear_using_JT();
+ }
+ 
+ inline void ObjectMonitor::clear_using_JT() {
+   // When clearing using a JavaThread, we leave _owner == DEFLATER_MARKER
+   // and _count < 0 to force any racing threads to retry. Unlike other
+   // *_using_JT() functions, we cannot assert AsyncDeflateIdleMonitors
+   // or Thread::current()->is_Java_thread() because clear() calls this
+   // function for the rest of its checks.
+ 
+   assert(_header != NULL, "Fatal logic error in ObjectMonitor header!");
    assert(_waiters == 0, "Fatal logic error in ObjectMonitor waiters!");
    assert(_recursions == 0, "Fatal logic error in ObjectMonitor recursions!");
    assert(_object != NULL, "Fatal logic error in ObjectMonitor object!");
!   // Do not assert _ref_count == 0 here because a racing thread could
!   // increment _ref_count, observe _owner == DEFLATER_MARKER and then
!   // decrement _ref_count.
  
+   set_allocation_state(Free);
    _header = NULL;
    _object = NULL;
+   // Do not clear _ref_count here because _ref_count is for indicating
+   // that the ObjectMonitor* is in use which is orthogonal to whether
+   // the ObjectMonitor itself is in use for a locking operation.
  }
  
  inline void* ObjectMonitor::object() const {
    return _object;
  }
*** 105,110 ****
--- 125,185 ----
  inline void ObjectMonitor::set_owner(void* owner) {
    _owner = owner;
    _recursions = 0;
  }
  
+ inline void ObjectMonitor::set_allocation_state(ObjectMonitor::AllocationState s) {
+   _allocation_state = s;
+ }
+ 
+ inline ObjectMonitor::AllocationState ObjectMonitor::allocation_state() const {
+   return _allocation_state;
+ }
+ 
+ inline bool ObjectMonitor::is_free() const {
+   return _allocation_state == Free;
+ }
+ 
+ inline bool ObjectMonitor::is_active() const {
+   return !is_free();
+ }
+ 
+ inline bool ObjectMonitor::is_old() const {
+   return _allocation_state == Old;
+ }
+ 
+ inline bool ObjectMonitor::is_new() const {
+   return _allocation_state == New;
+ }
+ 
+ inline void ObjectMonitor::dec_ref_count() {
+   // The decrement needs to be MO_ACQ_REL. At the moment, the Atomic::dec
+   // backend on PPC does not yet conform to these requirements. Therefore
+   // the decrement is simulated with an Atomic::sub(1, &addr). Without
+   // this MO_ACQ_REL Atomic::dec simulation, AsyncDeflateIdleMonitors is
+   // not safe.
+   Atomic::sub((jint)1, &_ref_count);
+   guarantee(_ref_count >= 0, "sanity check: ref_count=%d", _ref_count);
+ }
+ 
+ inline void ObjectMonitor::inc_ref_count() {
+   // The increment needs to be MO_SEQ_CST. At the moment, the Atomic::inc
+   // backend on PPC does not yet conform to these requirements. Therefore
+   // the increment is simulated with a load phi; cas phi + 1; loop.
+   // Without this MO_SEQ_CST Atomic::inc simulation, AsyncDeflateIdleMonitors
+   // is not safe.
+   for (;;) {
+     jint sample = OrderAccess::load_acquire(&_ref_count);
+     guarantee(sample >= 0, "sanity check: sample=%d", (int)sample);
+     if (Atomic::cmpxchg(sample + 1, &_ref_count, sample) == sample) {
+       // Incremented _ref_count without interference.
+       return;
+     }
+     // Implied else: Saw interference so loop and try again.
+   }
+ }
+ 
+ inline jint ObjectMonitor::ref_count() const {
+   return OrderAccess::load_acquire(&_ref_count);
+ }
+ 
  #endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP