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src/hotspot/share/runtime/objectMonitor.hpp
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rev 54572 : Checkpoint latest preliminary review patches for full OpenJDK review; merge with 8222295.patch.
rev 54573 : imported patch dcubed.monitor_deflate_conc.v2.01
@@ -134,10 +134,11 @@
OM_INTERRUPTED, // Thread.interrupt()
OM_TIMED_OUT // Object.wait() timed out
};
private:
+ friend class ObjectMonitorHandle;
friend class ObjectSynchronizer;
friend class ObjectWaiter;
friend class VMStructs;
volatile markOop _header; // displaced object header word - mark
@@ -147,10 +148,12 @@
private:
DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE,
sizeof(volatile markOop) + sizeof(void * volatile) +
sizeof(ObjectMonitor *));
protected: // protected for JvmtiRawMonitor
+ // Used by async deflation as a marker in the _owner field:
+ #define DEFLATER_MARKER reinterpret_cast<void*>(-1)
void * volatile _owner; // pointer to owning thread OR BasicLock
volatile jlong _previous_owner_tid; // thread id of the previous owner of the monitor
volatile intptr_t _recursions; // recursion count, 0 for first entry
ObjectWaiter * volatile _EntryList; // Threads blocked on entry or reentry.
// The list is actually composed of WaitNodes,
@@ -169,10 +172,17 @@
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
+ volatile jint _ref_count; // ref count for ObjectMonitor*
+ typedef enum {
+ Free = 0, // Free must be 0 for monitor to be free after memset(..,0,..).
+ New,
+ Old
+ } AllocationState;
+ AllocationState _allocation_state;
public:
static void Initialize();
// Only perform a PerfData operation if the PerfData object has been
@@ -230,16 +240,37 @@
volatile markOop* header_addr();
void set_header(markOop hdr);
intptr_t is_busy() const {
// TODO-FIXME: assert _owner == null implies _recursions = 0
+ // We do not include _ref_count in the is_busy() check 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.
return _contentions|_waiters|intptr_t(_owner)|intptr_t(_cxq)|intptr_t(_EntryList);
}
+ // Version of is_busy() that accounts for special values in
+ // _contentions and _owner when AsyncDeflateIdleMonitors is enabled.
+ intptr_t is_busy_async() const {
+ intptr_t ret_code = _waiters | intptr_t(_cxq) | intptr_t(_EntryList);
+ if (!AsyncDeflateIdleMonitors) {
+ ret_code |= _contentions | intptr_t(_owner);
+ } else {
+ if (_contentions > 0) {
+ ret_code |= _contentions;
+ }
+ if (_owner != DEFLATER_MARKER) {
+ ret_code |= intptr_t(_owner);
+ }
+ }
+ return ret_code;
+ }
+
intptr_t is_entered(Thread* current) const;
- void* owner() const;
+ void* owner() const; // Returns NULL if DEFLATER_MARKER is observed.
void set_owner(void* owner);
jint waiters() const;
jint contentions() const;
@@ -278,24 +309,34 @@
public:
void* object() const;
void* object_addr();
void set_object(void* obj);
+ void set_allocation_state(AllocationState s);
+ AllocationState allocation_state() const;
+ bool is_free() const;
+ bool is_active() const;
+ bool is_old() const;
+ bool is_new() const;
+ void dec_ref_count();
+ void inc_ref_count();
+ jint ref_count() const;
bool check(TRAPS); // true if the thread owns the monitor.
void check_slow(TRAPS);
void clear();
+ void clear_using_JT();
- void enter(TRAPS);
+ bool enter(TRAPS); // Returns false if monitor is being async deflated and caller should retry locking the object.
void exit(bool not_suspended, TRAPS);
void wait(jlong millis, bool interruptable, TRAPS);
void notify(TRAPS);
void notifyAll(TRAPS);
// Use the following at your own risk
intptr_t complete_exit(TRAPS);
- void reenter(intptr_t recursions, TRAPS);
+ bool reenter(intptr_t recursions, TRAPS); // Returns false if monitor is being async deflated and caller should retry locking the object.
private:
void AddWaiter(ObjectWaiter * waiter);
void INotify(Thread * Self);
ObjectWaiter * DequeueWaiter();
@@ -306,8 +347,40 @@
int TryLock(Thread * Self);
int NotRunnable(Thread * Self, Thread * Owner);
int TrySpin(Thread * Self);
void ExitEpilog(Thread * Self, ObjectWaiter * Wakee);
bool ExitSuspendEquivalent(JavaThread * Self);
+ void install_displaced_markword_in_object(const oop obj);
+};
+
+// A helper object for managing an ObjectMonitor*'s ref_count. There
+// are special safety considerations when async deflation is used.
+class ObjectMonitorHandle : public StackObj {
+ private:
+ ObjectMonitor * _om_ptr;
+ public:
+ ObjectMonitorHandle() { _om_ptr = NULL; }
+ ~ObjectMonitorHandle();
+
+ ObjectMonitor * om_ptr() const { return _om_ptr; }
+ // Save the ObjectMonitor* associated with the specified markOop and
+ // increment the ref_count.
+ bool save_om_ptr(oop object, markOop mark);
+
+ // For internal used by ObjectSynchronizer::monitors_iterate().
+ ObjectMonitorHandle(ObjectMonitor * _om_ptr);
+ // For internal use by ObjectSynchronizer::inflate().
+ void set_om_ptr(ObjectMonitor * om_ptr);
};
+// Macro to use guarantee() for more strict AsyncDeflateIdleMonitors
+// checks and assert() otherwise.
+#define ADIM_guarantee(p, ...) \
+ do { \
+ if (AsyncDeflateIdleMonitors) { \
+ guarantee(p, __VA_ARGS__); \
+ } else { \
+ assert(p, __VA_ARGS__); \
+ } \
+ } while (0)
+
#endif // SHARE_RUNTIME_OBJECTMONITOR_HPP
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