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src/hotspot/share/runtime/objectMonitor.inline.hpp
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rev 59077 : 8153224.v2.09b.patch combined with 8153224.v2.10.patch; merge with jdk-15+21.
rev 59078 : eosterlund v2.10 CR: reorganize deflate_monitor_using_JT() to use "early exit" style; dcubed - clarify/fix/rearrange a few comments in deflate_monitor_using_JT(); eosterlund v2.10 CR: simplify install_displaced_markword_in_object() and save_om_ptr(); save_om_ptr()'s call to install_displaced_markword_in_object() can race with the deflater thread's clearing of the object field so handle that; fold 8153224.OMHandle_experiment into 8153224.v2.11.patch; merge with jdk-15+21.
@@ -50,23 +50,59 @@
inline jint ObjectMonitor::waiters() const {
return _waiters;
}
+// Returns NULL if DEFLATER_MARKER is observed.
inline void* ObjectMonitor::owner() const {
- return _owner;
+ void* owner = _owner;
+ return owner != DEFLATER_MARKER ? owner : NULL;
+}
+
+// Returns true if owner field == DEFLATER_MARKER and false otherwise.
+// This accessor is called when we really need to know if the owner
+// field == DEFLATER_MARKER and any non-NULL value won't do the trick.
+inline bool ObjectMonitor::owner_is_DEFLATER_MARKER() {
+ return _owner == DEFLATER_MARKER;
+}
+
+// Returns true if 'this' is being async deflated and false otherwise.
+inline bool ObjectMonitor::is_being_async_deflated() {
+ return owner_is_DEFLATER_MARKER() && contentions() < 0;
}
inline void ObjectMonitor::clear() {
assert(Atomic::load(&_header).value() != 0, "must be non-zero");
- assert(_contentions == 0, "must be 0: contentions=%d", _contentions);
+ assert(_owner == NULL, "must be NULL: owner=" INTPTR_FORMAT, p2i(_owner));
+
+ Atomic::store(&_header, markWord::zero());
+
+ clear_using_JT();
+}
+
+inline void ObjectMonitor::clear_using_JT() {
+ // 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.
+
+ if (AsyncDeflateIdleMonitors) {
+ // Async deflation protocol uses the header, owner and contentions
+ // fields. While the ObjectMonitor being deflated is on the global free
+ // list, we leave those three fields alone; owner == DEFLATER_MARKER
+ // and contentions < 0 will force any racing threads to retry. The
+ // header field is used by install_displaced_markword_in_object()
+ // to restore the object's header so we cannot check its value here.
+ guarantee(_owner == NULL || _owner == DEFLATER_MARKER,
+ "must be NULL or DEFLATER_MARKER: owner=" INTPTR_FORMAT,
+ p2i(_owner));
+ }
+ assert(contentions() <= 0, "must not be positive: contentions=%d", contentions());
assert(_waiters == 0, "must be 0: waiters=%d", _waiters);
assert(_recursions == 0, "must be 0: recursions=" INTX_FORMAT, _recursions);
assert(_object != NULL, "must be non-NULL");
- assert(_owner == NULL, "must be NULL: owner=" INTPTR_FORMAT, p2i(_owner));
- Atomic::store(&_header, markWord::zero());
+ set_allocation_state(Free);
_object = NULL;
}
inline void* ObjectMonitor::object() const {
return _object;
@@ -78,43 +114,60 @@
inline void ObjectMonitor::set_object(void* obj) {
_object = obj;
}
-// return number of threads contending for this monitor
+// Return number of threads contending for this monitor.
inline jint ObjectMonitor::contentions() const {
- return _contentions;
+ return Atomic::load(&_contentions);
}
// Clear _owner field; current value must match old_value.
inline void ObjectMonitor::release_clear_owner(void* old_value) {
- DEBUG_ONLY(void* prev = Atomic::load(&_owner);)
- assert(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
+ void* prev = Atomic::load(&_owner);
+ ADIM_guarantee(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
Atomic::release_store(&_owner, (void*)NULL);
log_trace(monitorinflation, owner)("release_clear_owner(): mid="
INTPTR_FORMAT ", old_value=" INTPTR_FORMAT,
p2i(this), p2i(old_value));
}
// Simply set _owner field to new_value; current value must match old_value.
// (Simple means no memory sync needed.)
inline void ObjectMonitor::set_owner_from(void* old_value, void* new_value) {
- DEBUG_ONLY(void* prev = Atomic::load(&_owner);)
- assert(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
+ void* prev = Atomic::load(&_owner);
+ ADIM_guarantee(prev == old_value, "unexpected prev owner=" INTPTR_FORMAT
", expected=" INTPTR_FORMAT, p2i(prev), p2i(old_value));
Atomic::store(&_owner, new_value);
log_trace(monitorinflation, owner)("set_owner_from(): mid="
INTPTR_FORMAT ", old_value=" INTPTR_FORMAT
", new_value=" INTPTR_FORMAT, p2i(this),
p2i(old_value), p2i(new_value));
}
+// Simply set _owner field to new_value; current value must match old_value1 or old_value2.
+// (Simple means no memory sync needed.)
+inline void ObjectMonitor::set_owner_from(void* old_value1, void* old_value2, void* new_value) {
+ void* prev = Atomic::load(&_owner);
+ ADIM_guarantee(prev == old_value1 || prev == old_value2,
+ "unexpected prev owner=" INTPTR_FORMAT ", expected1="
+ INTPTR_FORMAT " or expected2=" INTPTR_FORMAT, p2i(prev),
+ p2i(old_value1), p2i(old_value2));
+ _owner = new_value;
+ log_trace(monitorinflation, owner)("set_owner_from(old1=" INTPTR_FORMAT
+ ", old2=" INTPTR_FORMAT "): mid="
+ INTPTR_FORMAT ", prev=" INTPTR_FORMAT
+ ", new=" INTPTR_FORMAT, p2i(old_value1),
+ p2i(old_value2), p2i(this), p2i(prev),
+ p2i(new_value));
+}
+
// Simply set _owner field to self; current value must match basic_lock_p.
inline void ObjectMonitor::set_owner_from_BasicLock(void* basic_lock_p, Thread* self) {
- DEBUG_ONLY(void* prev = Atomic::load(&_owner);)
- assert(prev == basic_lock_p, "unexpected prev owner=" INTPTR_FORMAT
+ void* prev = Atomic::load(&_owner);
+ ADIM_guarantee(prev == basic_lock_p, "unexpected prev owner=" INTPTR_FORMAT
", expected=" INTPTR_FORMAT, p2i(prev), p2i(basic_lock_p));
// Non-null owner field to non-null owner field is safe without
// cmpxchg() as long as all readers can tolerate either flavor.
Atomic::store(&_owner, self);
log_trace(monitorinflation, owner)("set_owner_from_BasicLock(): mid="
@@ -135,10 +188,30 @@
p2i(prev), p2i(new_value));
}
return prev;
}
+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_old() const {
+ return _allocation_state == Old;
+}
+
+inline bool ObjectMonitor::is_new() const {
+ return _allocation_state == New;
+}
+
// The _next_om field can be concurrently read and modified so we
// use Atomic operations to disable compiler optimizations that
// might try to elide loading and/or storing this field.
inline ObjectMonitor* ObjectMonitor::next_om() const {
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