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src/hotspot/share/runtime/biasedLocking.cpp
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rev 54697 : imported patch 8221734-v2-merge
rev 54698 : imported patch 8221734-v2
*** 619,631 ****
event->set_disableBiasing(disabled_bias);
set_safepoint_id(event);
event->commit();
}
! BiasedLocking::Condition BiasedLocking::revoke_and_rebias(Handle obj, bool attempt_rebias, TRAPS) {
! assert(!SafepointSynchronize::is_at_safepoint(), "must not be called while at safepoint");
!
// We can revoke the biases of anonymously-biased objects
// efficiently enough that we should not cause these revocations to
// update the heuristics because doing so may cause unwanted bulk
// revocations (which are expensive) to occur.
markOop mark = obj->mark();
--- 619,629 ----
event->set_disableBiasing(disabled_bias);
set_safepoint_id(event);
event->commit();
}
! BiasedLocking::Condition fast_revoke(Handle obj, bool attempt_rebias, JavaThread* thread = NULL) {
// We can revoke the biases of anonymously-biased objects
// efficiently enough that we should not cause these revocations to
// update the heuristics because doing so may cause unwanted bulk
// revocations (which are expensive) to occur.
markOop mark = obj->mark();
*** 638,648 ****
// the bias of the object.
markOop biased_value = mark;
markOop unbiased_prototype = markOopDesc::prototype()->set_age(mark->age());
markOop res_mark = obj->cas_set_mark(unbiased_prototype, mark);
if (res_mark == biased_value) {
! return BIAS_REVOKED;
}
} else if (mark->has_bias_pattern()) {
Klass* k = obj->klass();
markOop prototype_header = k->prototype_header();
if (!prototype_header->has_bias_pattern()) {
--- 636,646 ----
// the bias of the object.
markOop biased_value = mark;
markOop unbiased_prototype = markOopDesc::prototype()->set_age(mark->age());
markOop res_mark = obj->cas_set_mark(unbiased_prototype, mark);
if (res_mark == biased_value) {
! return BiasedLocking::BIAS_REVOKED;
}
} else if (mark->has_bias_pattern()) {
Klass* k = obj->klass();
markOop prototype_header = k->prototype_header();
if (!prototype_header->has_bias_pattern()) {
*** 653,697 ****
// by another thread so we simply return and let the caller deal
// with it.
markOop biased_value = mark;
markOop res_mark = obj->cas_set_mark(prototype_header, mark);
assert(!obj->mark()->has_bias_pattern(), "even if we raced, should still be revoked");
! return BIAS_REVOKED;
} else if (prototype_header->bias_epoch() != mark->bias_epoch()) {
// The epoch of this biasing has expired indicating that the
// object is effectively unbiased. Depending on whether we need
// to rebias or revoke the bias of this object we can do it
// efficiently enough with a CAS that we shouldn't update the
// heuristics. This is normally done in the assembly code but we
// can reach this point due to various points in the runtime
// needing to revoke biases.
if (attempt_rebias) {
- assert(THREAD->is_Java_thread(), "");
markOop biased_value = mark;
! markOop rebiased_prototype = markOopDesc::encode((JavaThread*) THREAD, mark->age(), prototype_header->bias_epoch());
markOop res_mark = obj->cas_set_mark(rebiased_prototype, mark);
if (res_mark == biased_value) {
! return BIAS_REVOKED_AND_REBIASED;
}
} else {
markOop biased_value = mark;
markOop unbiased_prototype = markOopDesc::prototype()->set_age(mark->age());
markOop res_mark = obj->cas_set_mark(unbiased_prototype, mark);
if (res_mark == biased_value) {
! return BIAS_REVOKED;
}
}
}
}
HeuristicsResult heuristics = update_heuristics(obj(), attempt_rebias);
if (heuristics == HR_NOT_BIASED) {
return NOT_BIASED;
} else if (heuristics == HR_SINGLE_REVOKE) {
Klass *k = obj->klass();
markOop prototype_header = k->prototype_header();
! if (mark->biased_locker() == THREAD &&
prototype_header->bias_epoch() == mark->bias_epoch()) {
// A thread is trying to revoke the bias of an object biased
// toward it, again likely due to an identity hash code
// computation. We can again avoid a safepoint in this case
// since we are only going to walk our own stack. There are no
--- 651,738 ----
// by another thread so we simply return and let the caller deal
// with it.
markOop biased_value = mark;
markOop res_mark = obj->cas_set_mark(prototype_header, mark);
assert(!obj->mark()->has_bias_pattern(), "even if we raced, should still be revoked");
! return BiasedLocking::BIAS_REVOKED;
} else if (prototype_header->bias_epoch() != mark->bias_epoch()) {
// The epoch of this biasing has expired indicating that the
// object is effectively unbiased. Depending on whether we need
// to rebias or revoke the bias of this object we can do it
// efficiently enough with a CAS that we shouldn't update the
// heuristics. This is normally done in the assembly code but we
// can reach this point due to various points in the runtime
// needing to revoke biases.
if (attempt_rebias) {
markOop biased_value = mark;
! markOop rebiased_prototype = markOopDesc::encode(thread, mark->age(), prototype_header->bias_epoch());
markOop res_mark = obj->cas_set_mark(rebiased_prototype, mark);
if (res_mark == biased_value) {
! return BiasedLocking::BIAS_REVOKED_AND_REBIASED;
}
} else {
markOop biased_value = mark;
markOop unbiased_prototype = markOopDesc::prototype()->set_age(mark->age());
markOop res_mark = obj->cas_set_mark(unbiased_prototype, mark);
if (res_mark == biased_value) {
! return BiasedLocking::BIAS_REVOKED;
! }
! }
! }
! }
! return BiasedLocking::NOT_REVOKED;
! }
!
! BiasedLocking::Condition BiasedLocking::revoke_and_rebias_in_handshake(Handle obj, TRAPS) {
! BiasedLocking::Condition bc = fast_revoke(obj, false);
! if (bc != NOT_REVOKED) {
! return bc;
! }
!
! markOop mark = obj->mark();
! if (!mark->has_bias_pattern()) {
! return NOT_BIASED;
}
+
+ Klass *k = obj->klass();
+ markOop prototype_header = k->prototype_header();
+ if (mark->biased_locker() == THREAD && prototype_header->bias_epoch() == mark->bias_epoch()) {
+ ResourceMark rm;
+ log_info(biasedlocking)("Revoking bias by walking my own stack:");
+ EventBiasedLockSelfRevocation event;
+ BiasedLocking::Condition cond = revoke_bias(obj(), false, false, (JavaThread*) THREAD, NULL);
+ ((JavaThread*) THREAD)->set_cached_monitor_info(NULL);
+ assert(cond == BIAS_REVOKED, "why not?");
+ if (event.should_commit()) {
+ post_self_revocation_event(&event, k);
}
+ return cond;
}
+
+ ShouldNotReachHere();
+
+ return NOT_REVOKED;
+ }
+
+ BiasedLocking::Condition BiasedLocking::revoke_and_rebias(Handle obj, bool attempt_rebias, TRAPS) {
+ assert(!SafepointSynchronize::is_at_safepoint(), "must not be called while at safepoint");
+ assert(!attempt_rebias || THREAD->is_Java_thread(), "");
+
+ BiasedLocking::Condition bc = fast_revoke(obj, attempt_rebias, (JavaThread*) THREAD);
+ if (bc != NOT_REVOKED) {
+ return bc;
}
HeuristicsResult heuristics = update_heuristics(obj(), attempt_rebias);
if (heuristics == HR_NOT_BIASED) {
return NOT_BIASED;
} else if (heuristics == HR_SINGLE_REVOKE) {
+ markOop mark = obj->mark();
Klass *k = obj->klass();
markOop prototype_header = k->prototype_header();
! if (mark->has_bias_pattern() &&
! mark->biased_locker() == ((JavaThread*) THREAD) &&
prototype_header->bias_epoch() == mark->bias_epoch()) {
// A thread is trying to revoke the bias of an object biased
// toward it, again likely due to an identity hash code
// computation. We can again avoid a safepoint in this case
// since we are only going to walk our own stack. There are no
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