src/share/vm/runtime/mutex.hpp

rev 12096 : 8166970: Adapt mutex padding according to DEFAULT_CACHE_LINE_SIZE
Reviewed-by:

*** 79,93 ****
  // See orderAccess.hpp.  We assume throughout the VM that mutex lock and
  // try_lock do fence-lock-acquire, and that unlock does a release-unlock,
  // *in that order*.  If their implementations change such that these
  // assumptions are violated, a whole lot of code will break.
  
! // The default length of monitor name is chosen to be 64 to avoid false sharing.
! static const int MONITOR_NAME_LEN = 64;
! 
! class Monitor : public CHeapObj<mtInternal> {
! 
   public:
    // A special lock: Is a lock where you are guaranteed not to block while you are
    // holding it, i.e., no vm operation can happen, taking other locks, etc.
    // NOTE: It is critical that the rank 'special' be the lowest (earliest)
    // (except for "event"?) for the deadlock detection to work correctly.
--- 79,89 ----
  // See orderAccess.hpp.  We assume throughout the VM that mutex lock and
  // try_lock do fence-lock-acquire, and that unlock does a release-unlock,
  // *in that order*.  If their implementations change such that these
  // assumptions are violated, a whole lot of code will break.
  
! class MonitorBase : public CHeapObj<mtInternal> {
   public:
    // A special lock: Is a lock where you are guaranteed not to block while you are
    // holding it, i.e., no vm operation can happen, taking other locks, etc.
    // NOTE: It is critical that the rank 'special' be the lowest (earliest)
    // (except for "event"?) for the deadlock detection to work correctly.
*** 127,153 ****
    ParkEvent * volatile _OnDeck ;         // heir-presumptive
    volatile intptr_t _WaitLock [1] ;      // Protects _WaitSet
    ParkEvent * volatile  _WaitSet ;       // LL of ParkEvents
    volatile bool     _snuck;              // Used for sneaky locking (evil).
    int NotifyCount ;                      // diagnostic assist
-   char _name[MONITOR_NAME_LEN];          // Name of mutex
  
    // Debugging fields for naming, deadlock detection, etc. (some only used in debug mode)
  #ifndef PRODUCT
    bool      _allow_vm_block;
    debug_only(int _rank;)                 // rank (to avoid/detect potential deadlocks)
    debug_only(Monitor * _next;)           // Used by a Thread to link up owned locks
    debug_only(Thread* _last_owner;)       // the last thread to own the lock
-   debug_only(static bool contains(Monitor * locks, Monitor * lock);)
-   debug_only(static Monitor * get_least_ranked_lock(Monitor * locks);)
-   debug_only(Monitor * get_least_ranked_lock_besides_this(Monitor * locks);)
  #endif
  
-   void set_owner_implementation(Thread* owner)                        PRODUCT_RETURN;
-   void check_prelock_state     (Thread* thread)                       PRODUCT_RETURN;
-   void check_block_state       (Thread* thread)                       PRODUCT_RETURN;
- 
    // platform-dependent support code can go here (in os_<os_family>.cpp)
   public:
    enum {
      _no_safepoint_check_flag    = true,
      _allow_vm_block_flag        = true,
--- 123,141 ----
*** 175,184 ****
--- 163,194 ----
    enum WaitResults {
      CONDVAR_EVENT,         // Wait returned because of condition variable notification
      INTERRUPT_EVENT,       // Wait returned because waiting thread was interrupted
      NUMBER_WAIT_RESULTS
    };
+ };
+ 
+ class Monitor : public MonitorBase {
+  protected:
+   // The default length of monitor name is chosen to avoid false sharing.
+   enum {
+     CACHE_LINE_PADDING = DEFAULT_CACHE_LINE_SIZE - sizeof(MonitorBase),
+     MONITOR_NAME_LEN = CACHE_LINE_PADDING > 64 ? CACHE_LINE_PADDING : 64
+   };
+   char _name[MONITOR_NAME_LEN];          // Name of mutex
+   // Other fields should be declared in MonitorBase.
+ 
+  public:
+ #ifndef PRODUCT
+   debug_only(static bool contains(Monitor * locks, Monitor * lock);)
+   debug_only(static Monitor * get_least_ranked_lock(Monitor * locks);)
+   debug_only(Monitor * get_least_ranked_lock_besides_this(Monitor * locks);)
+ #endif
+ 
+   void set_owner_implementation(Thread* owner)                        PRODUCT_RETURN;
+   void check_prelock_state     (Thread* thread)                       PRODUCT_RETURN;
+   void check_block_state       (Thread* thread)                       PRODUCT_RETURN;
  
   private:
     int  TrySpin (Thread * Self) ;
     int  TryLock () ;
     int  TryFast () ;