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-rw-r--r--runtime/monitor.cc108
1 files changed, 69 insertions, 39 deletions
diff --git a/runtime/monitor.cc b/runtime/monitor.cc
index 5ed8c7ded9..45a971d22d 100644
--- a/runtime/monitor.cc
+++ b/runtime/monitor.cc
@@ -165,7 +165,7 @@ bool Monitor::Install(Thread* self) {
return false;
}
}
- LockWord fat(this);
+ LockWord fat(this, lw.ReadBarrierState());
// Publish the updated lock word, which may race with other threads.
bool success = GetObject()->CasLockWordWeakSequentiallyConsistent(lw, fat);
// Lock profiling.
@@ -610,15 +610,22 @@ bool Monitor::Deflate(Thread* self, mirror::Object* obj) {
return false;
}
// Deflate to a thin lock.
- obj->SetLockWord(LockWord::FromThinLockId(owner->GetThreadId(), monitor->lock_count_), false);
+ LockWord new_lw = LockWord::FromThinLockId(owner->GetThreadId(), monitor->lock_count_,
+ lw.ReadBarrierState());
+ // Assume no concurrent read barrier state changes as mutators are suspended.
+ obj->SetLockWord(new_lw, false);
VLOG(monitor) << "Deflated " << obj << " to thin lock " << owner->GetTid() << " / "
<< monitor->lock_count_;
} else if (monitor->HasHashCode()) {
- obj->SetLockWord(LockWord::FromHashCode(monitor->GetHashCode()), false);
+ LockWord new_lw = LockWord::FromHashCode(monitor->GetHashCode(), lw.ReadBarrierState());
+ // Assume no concurrent read barrier state changes as mutators are suspended.
+ obj->SetLockWord(new_lw, false);
VLOG(monitor) << "Deflated " << obj << " to hash monitor " << monitor->GetHashCode();
} else {
// No lock and no hash, just put an empty lock word inside the object.
- obj->SetLockWord(LockWord(), false);
+ LockWord new_lw = LockWord::FromDefault(lw.ReadBarrierState());
+ // Assume no concurrent read barrier state changes as mutators are suspended.
+ obj->SetLockWord(new_lw, false);
VLOG(monitor) << "Deflated" << obj << " to empty lock word";
}
// The monitor is deflated, mark the object as nullptr so that we know to delete it during the
@@ -704,7 +711,7 @@ mirror::Object* Monitor::MonitorEnter(Thread* self, mirror::Object* obj) {
LockWord lock_word = h_obj->GetLockWord(true);
switch (lock_word.GetState()) {
case LockWord::kUnlocked: {
- LockWord thin_locked(LockWord::FromThinLockId(thread_id, 0));
+ LockWord thin_locked(LockWord::FromThinLockId(thread_id, 0, lock_word.ReadBarrierState()));
if (h_obj->CasLockWordWeakSequentiallyConsistent(lock_word, thin_locked)) {
// CasLockWord enforces more than the acquire ordering we need here.
return h_obj.Get(); // Success!
@@ -717,9 +724,18 @@ mirror::Object* Monitor::MonitorEnter(Thread* self, mirror::Object* obj) {
// We own the lock, increase the recursion count.
uint32_t new_count = lock_word.ThinLockCount() + 1;
if (LIKELY(new_count <= LockWord::kThinLockMaxCount)) {
- LockWord thin_locked(LockWord::FromThinLockId(thread_id, new_count));
- h_obj->SetLockWord(thin_locked, true);
- return h_obj.Get(); // Success!
+ LockWord thin_locked(LockWord::FromThinLockId(thread_id, new_count,
+ lock_word.ReadBarrierState()));
+ if (!kUseReadBarrier) {
+ h_obj->SetLockWord(thin_locked, true);
+ return h_obj.Get(); // Success!
+ } else {
+ // Use CAS to preserve the read barrier state.
+ if (h_obj->CasLockWordWeakSequentiallyConsistent(lock_word, thin_locked)) {
+ return h_obj.Get(); // Success!
+ }
+ }
+ continue; // Go again.
} else {
// We'd overflow the recursion count, so inflate the monitor.
InflateThinLocked(self, h_obj, lock_word, 0);
@@ -762,43 +778,57 @@ bool Monitor::MonitorExit(Thread* self, mirror::Object* obj) {
DCHECK(self != NULL);
DCHECK(obj != NULL);
obj = FakeUnlock(obj);
- LockWord lock_word = obj->GetLockWord(true);
StackHandleScope<1> hs(self);
Handle<mirror::Object> h_obj(hs.NewHandle(obj));
- switch (lock_word.GetState()) {
- case LockWord::kHashCode:
- // Fall-through.
- case LockWord::kUnlocked:
- FailedUnlock(h_obj.Get(), self, nullptr, nullptr);
- return false; // Failure.
- case LockWord::kThinLocked: {
- uint32_t thread_id = self->GetThreadId();
- uint32_t owner_thread_id = lock_word.ThinLockOwner();
- if (owner_thread_id != thread_id) {
- // TODO: there's a race here with the owner dying while we unlock.
- Thread* owner =
- Runtime::Current()->GetThreadList()->FindThreadByThreadId(lock_word.ThinLockOwner());
- FailedUnlock(h_obj.Get(), self, owner, nullptr);
+ while (true) {
+ LockWord lock_word = obj->GetLockWord(true);
+ switch (lock_word.GetState()) {
+ case LockWord::kHashCode:
+ // Fall-through.
+ case LockWord::kUnlocked:
+ FailedUnlock(h_obj.Get(), self, nullptr, nullptr);
return false; // Failure.
- } else {
- // We own the lock, decrease the recursion count.
- if (lock_word.ThinLockCount() != 0) {
- uint32_t new_count = lock_word.ThinLockCount() - 1;
- LockWord thin_locked(LockWord::FromThinLockId(thread_id, new_count));
- h_obj->SetLockWord(thin_locked, true);
+ case LockWord::kThinLocked: {
+ uint32_t thread_id = self->GetThreadId();
+ uint32_t owner_thread_id = lock_word.ThinLockOwner();
+ if (owner_thread_id != thread_id) {
+ // TODO: there's a race here with the owner dying while we unlock.
+ Thread* owner =
+ Runtime::Current()->GetThreadList()->FindThreadByThreadId(lock_word.ThinLockOwner());
+ FailedUnlock(h_obj.Get(), self, owner, nullptr);
+ return false; // Failure.
} else {
- h_obj->SetLockWord(LockWord(), true);
+ // We own the lock, decrease the recursion count.
+ LockWord new_lw = LockWord::Default();
+ if (lock_word.ThinLockCount() != 0) {
+ uint32_t new_count = lock_word.ThinLockCount() - 1;
+ new_lw = LockWord::FromThinLockId(thread_id, new_count, lock_word.ReadBarrierState());
+ } else {
+ new_lw = LockWord::FromDefault(lock_word.ReadBarrierState());
+ }
+ if (!kUseReadBarrier) {
+ DCHECK_EQ(new_lw.ReadBarrierState(), 0U);
+ h_obj->SetLockWord(new_lw, true);
+ // Success!
+ return true;
+ } else {
+ // Use CAS to preserve the read barrier state.
+ if (h_obj->CasLockWordWeakSequentiallyConsistent(lock_word, new_lw)) {
+ // Success!
+ return true;
+ }
+ }
+ continue; // Go again.
}
- return true; // Success!
}
- }
- case LockWord::kFatLocked: {
- Monitor* mon = lock_word.FatLockMonitor();
- return mon->Unlock(self);
- }
- default: {
- LOG(FATAL) << "Invalid monitor state " << lock_word.GetState();
- return false;
+ case LockWord::kFatLocked: {
+ Monitor* mon = lock_word.FatLockMonitor();
+ return mon->Unlock(self);
+ }
+ default: {
+ LOG(FATAL) << "Invalid monitor state " << lock_word.GetState();
+ return false;
+ }
}
}
}
generated by cgit v1.2.3-59-g8ed1b (git 2.39.0) at 2025-10-21 07:53:05 +0000