8230003: Make Monitor inherit from Mutex

Reverse inheritance that makes more sense.

Reviewed-by: dholmes, rehn, pchilanomate

src/hotspot/share/compiler/compileBroker.cpp

@@ -2674,8 +2674,8 @@ void CompileBroker::print_heapinfo(outputStream* out, const char* function, size
   // for the entire duration of aggregation and printing. That makes sure
   // we see a consistent picture and do not run into issues caused by
   // the CodeHeap being altered concurrently.
-  Monitor* global_lock   = allFun ? CodeCache_lock : NULL;
-  Monitor* function_lock = allFun ? NULL : CodeCache_lock;
+  Mutex* global_lock   = allFun ? CodeCache_lock : NULL;
+  Mutex* function_lock = allFun ? NULL : CodeCache_lock;
   ts_global.update(); // record starting point
   MutexLocker mu2(global_lock, Mutex::_no_safepoint_check_flag);
   if (global_lock != NULL) {

src/hotspot/share/jfr/recorder/repository/jfrEmergencyDump.cpp

@@ -356,9 +356,9 @@ static void prepare_for_emergency_dump(Thread* thread) {
   }
 
 #ifdef ASSERT
-  Monitor* owned_lock = thread->owned_locks();
+  Mutex* owned_lock = thread->owned_locks();
   while (owned_lock != NULL) {
-    Monitor* next = owned_lock->next();
+    Mutex* next = owned_lock->next();
     owned_lock->unlock();
     owned_lock = next;
   }

src/hotspot/share/logging/logTag.hpp

@@ -171,7 +171,7 @@
   LOG_TAG(mirror) \
   LOG_TAG(verification) \
   LOG_TAG(verify) \
-  LOG_TAG(vmmonitor) \
+  LOG_TAG(vmmutex) \
   LOG_TAG(vmoperation) \
   LOG_TAG(vmthread) \
   LOG_TAG(vtables) \

src/hotspot/share/runtime/interfaceSupport.inline.hpp

@@ -254,30 +254,30 @@ class ThreadBlockInVM : public ThreadStateTransition {
 };
 
 // Unlike ThreadBlockInVM, this class is designed to avoid certain deadlock scenarios while making
-// transitions inside class Monitor in cases where we need to block for a safepoint or handshake. It
-// receives an extra argument compared to ThreadBlockInVM, the address of a pointer to the monitor we
-// are trying to acquire. This will be used to access and release the monitor if needed to avoid
+// transitions inside class Mutex in cases where we need to block for a safepoint or handshake. It
+// receives an extra argument compared to ThreadBlockInVM, the address of a pointer to the mutex we
+// are trying to acquire. This will be used to access and release the mutex if needed to avoid
 // said deadlocks.
 // It works like ThreadBlockInVM but differs from it in two ways:
 // - When transitioning in (constructor), it checks for safepoints without blocking, i.e., calls
 //   back if needed to allow a pending safepoint to continue but does not block in it.
 // - When transitioning back (destructor), if there is a pending safepoint or handshake it releases
-//   the monitor that is only partially acquired.
+//   the mutex that is only partially acquired.
 class ThreadBlockInVMWithDeadlockCheck : public ThreadStateTransition {
  private:
-  Monitor** _in_flight_monitor_adr;
-
-  void release_monitor() {
-    assert(_in_flight_monitor_adr != NULL, "_in_flight_monitor_adr should have been set on constructor");
-    Monitor* in_flight_monitor = *_in_flight_monitor_adr;
-    if (in_flight_monitor != NULL) {
-      in_flight_monitor->release_for_safepoint();
-      *_in_flight_monitor_adr = NULL;
+  Mutex** _in_flight_mutex_addr;
+
+  void release_mutex() {
+    assert(_in_flight_mutex_addr != NULL, "_in_flight_mutex_addr should have been set on constructor");
+    Mutex* in_flight_mutex = *_in_flight_mutex_addr;
+    if (in_flight_mutex != NULL) {
+      in_flight_mutex->release_for_safepoint();
+      *_in_flight_mutex_addr = NULL;
     }
   }
  public:
-  ThreadBlockInVMWithDeadlockCheck(JavaThread* thread, Monitor** in_flight_monitor_adr)
-  : ThreadStateTransition(thread), _in_flight_monitor_adr(in_flight_monitor_adr) {
+  ThreadBlockInVMWithDeadlockCheck(JavaThread* thread, Mutex** in_flight_mutex_addr)
+  : ThreadStateTransition(thread), _in_flight_mutex_addr(in_flight_mutex_addr) {
     // Once we are blocked vm expects stack to be walkable
     thread->frame_anchor()->make_walkable(thread);
 
@@ -293,7 +293,7 @@ class ThreadBlockInVMWithDeadlockCheck : public ThreadStateTransition {
     _thread->set_thread_state_fence((JavaThreadState)(_thread_blocked_trans));
 
     if (SafepointMechanism::should_block(_thread)) {
-      release_monitor();
+      release_mutex();
       SafepointMechanism::block_if_requested(_thread);
     }
 

src/hotspot/share/runtime/mutex.cpp

@@ -33,27 +33,27 @@
 #include "utilities/macros.hpp"
 
 #ifdef ASSERT
-void Monitor::check_safepoint_state(Thread* thread, bool do_safepoint_check) {
+void Mutex::check_safepoint_state(Thread* thread, bool do_safepoint_check) {
   // If the JavaThread checks for safepoint, verify that the lock wasn't created with safepoint_check_never.
-  SafepointCheckRequired not_allowed = do_safepoint_check ?  Monitor::_safepoint_check_never :
-                                                             Monitor::_safepoint_check_always;
+  SafepointCheckRequired not_allowed = do_safepoint_check ?  Mutex::_safepoint_check_never :
+                                                             Mutex::_safepoint_check_always;
   assert(!thread->is_active_Java_thread() || _safepoint_check_required != not_allowed,
          "This lock should %s have a safepoint check for Java threads: %s",
          _safepoint_check_required ? "always" : "never", name());
 
   // If defined with safepoint_check_never, a NonJavaThread should never ask to safepoint check either.
-  assert(thread->is_Java_thread() || !do_safepoint_check || _safepoint_check_required != Monitor::_safepoint_check_never,
+  assert(thread->is_Java_thread() || !do_safepoint_check || _safepoint_check_required != Mutex::_safepoint_check_never,
          "NonJavaThread should not check for safepoint");
 }
 #endif // ASSERT
 
-void Monitor::lock(Thread * self) {
+void Mutex::lock(Thread * self) {
   check_safepoint_state(self, true);
 
   DEBUG_ONLY(check_prelock_state(self, true));
   assert(_owner != self, "invariant");
 
-  Monitor* in_flight_monitor = NULL;
+  Mutex* in_flight_mutex = NULL;
   DEBUG_ONLY(int retry_cnt = 0;)
   bool is_active_Java_thread = self->is_active_Java_thread();
   while (!_lock.try_lock()) {
@@ -62,18 +62,18 @@ void Monitor::lock(Thread * self) {
   #ifdef ASSERT
     check_block_state(self);
     if (retry_cnt++ > 3) {
-      log_trace(vmmonitor)("JavaThread " INTPTR_FORMAT " on %d attempt trying to acquire vmmonitor %s", p2i(self), retry_cnt, _name);
+      log_trace(vmmutex)("JavaThread " INTPTR_FORMAT " on %d attempt trying to acquire vmmutex %s", p2i(self), retry_cnt, _name);
     }
   #endif // ASSERT
 
     // Is it a JavaThread participating in the safepoint protocol.
     if (is_active_Java_thread) {
       assert(rank() > Mutex::special, "Potential deadlock with special or lesser rank mutex");
-      { ThreadBlockInVMWithDeadlockCheck tbivmdc((JavaThread *) self, &in_flight_monitor);
-        in_flight_monitor = this;  // save for ~ThreadBlockInVMWithDeadlockCheck
+      { ThreadBlockInVMWithDeadlockCheck tbivmdc((JavaThread *) self, &in_flight_mutex);
+        in_flight_mutex = this;  // save for ~ThreadBlockInVMWithDeadlockCheck
         _lock.lock();
       }
-      if (in_flight_monitor != NULL) {
+      if (in_flight_mutex != NULL) {
         // Not unlocked by ~ThreadBlockInVMWithDeadlockCheck
         break;
       }
@@ -87,7 +87,7 @@ void Monitor::lock(Thread * self) {
   set_owner(self);
 }
 
-void Monitor::lock() {
+void Mutex::lock() {
   this->lock(Thread::current());
 }
 
@@ -97,22 +97,22 @@ void Monitor::lock() {
 // safepoint-safe and so will prevent a safepoint from being reached. If used
 // in the wrong way this can lead to a deadlock with the safepoint code.
 
-void Monitor::lock_without_safepoint_check(Thread * self) {
+void Mutex::lock_without_safepoint_check(Thread * self) {
   check_safepoint_state(self, false);
   assert(_owner != self, "invariant");
   _lock.lock();
   assert_owner(NULL);
   set_owner(self);
 }
 
-void Monitor::lock_without_safepoint_check() {
+void Mutex::lock_without_safepoint_check() {
   lock_without_safepoint_check(Thread::current());
 }
 
 
 // Returns true if thread succeeds in grabbing the lock, otherwise false.
 
-bool Monitor::try_lock() {
+bool Mutex::try_lock() {
   Thread * const self = Thread::current();
   DEBUG_ONLY(check_prelock_state(self, false);)
 
@@ -124,12 +124,12 @@ bool Monitor::try_lock() {
   return false;
 }
 
-void Monitor::release_for_safepoint() {
+void Mutex::release_for_safepoint() {
   assert_owner(NULL);
   _lock.unlock();
 }
 
-void Monitor::unlock() {
+void Mutex::unlock() {
   assert_owner(Thread::current());
   set_owner(NULL);
   _lock.unlock();
@@ -147,7 +147,7 @@ void Monitor::notify_all() {
 
 #ifdef ASSERT
 void Monitor::assert_wait_lock_state(Thread* self) {
-  Monitor* least = get_least_ranked_lock_besides_this(self->owned_locks());
+  Mutex* least = get_least_ranked_lock_besides_this(self->owned_locks());
   assert(least != this, "Specification of get_least_... call above");
   if (least != NULL && least->rank() <= special) {
     ::tty->print("Attempting to wait on monitor %s/%d while holding"
@@ -194,10 +194,10 @@ bool Monitor::wait(long timeout, bool as_suspend_equivalent) {
   // abdicating the lock in wait
   set_owner(NULL);
   JavaThread *jt = (JavaThread *)self;
-  Monitor* in_flight_monitor = NULL;
+  Mutex* in_flight_mutex = NULL;
 
   {
-    ThreadBlockInVMWithDeadlockCheck tbivmdc(jt, &in_flight_monitor);
+    ThreadBlockInVMWithDeadlockCheck tbivmdc(jt, &in_flight_mutex);
     OSThreadWaitState osts(self->osthread(), false /* not Object.wait() */);
     if (as_suspend_equivalent) {
       jt->set_suspend_equivalent();
@@ -206,7 +206,7 @@ bool Monitor::wait(long timeout, bool as_suspend_equivalent) {
     }
 
     wait_status = _lock.wait(timeout);
-    in_flight_monitor = this;  // save for ~ThreadBlockInVMWithDeadlockCheck
+    in_flight_mutex = this;  // save for ~ThreadBlockInVMWithDeadlockCheck
 
     // were we externally suspended while we were waiting?
     if (as_suspend_equivalent && jt->handle_special_suspend_equivalent_condition()) {
@@ -220,7 +220,7 @@ bool Monitor::wait(long timeout, bool as_suspend_equivalent) {
     }
   }
 
-  if (in_flight_monitor != NULL) {
+  if (in_flight_mutex != NULL) {
     // Not unlocked by ~ThreadBlockInVMWithDeadlockCheck
     assert_owner(NULL);
     // Conceptually reestablish ownership of the lock.
@@ -232,7 +232,7 @@ bool Monitor::wait(long timeout, bool as_suspend_equivalent) {
   return wait_status != 0;          // return true IFF timeout
 }
 
-Monitor::~Monitor() {
+Mutex::~Mutex() {
   assert_owner(NULL);
 }
 
@@ -241,34 +241,34 @@ bool is_sometimes_ok(const char* name) {
   return (strcmp(name, "Threads_lock") == 0 || strcmp(name, "Heap_lock") == 0 || strcmp(name, "SR_lock") == 0);
 }
 
-Monitor::Monitor(int Rank, const char * name, bool allow_vm_block,
-                 SafepointCheckRequired safepoint_check_required) : _owner(NULL) {
+Mutex::Mutex(int Rank, const char * name, bool allow_vm_block,
+             SafepointCheckRequired safepoint_check_required) : _owner(NULL) {
   assert(os::mutex_init_done(), "Too early!");
   if (name == NULL) {
     strcpy(_name, "UNKNOWN");
   } else {
-    strncpy(_name, name, MONITOR_NAME_LEN - 1);
-    _name[MONITOR_NAME_LEN - 1] = '\0';
+    strncpy(_name, name, MUTEX_NAME_LEN - 1);
+    _name[MUTEX_NAME_LEN - 1] = '\0';
   }
 #ifdef ASSERT
   _allow_vm_block  = allow_vm_block;
   _rank            = Rank;
   _safepoint_check_required = safepoint_check_required;
 
-  assert(_safepoint_check_required != Monitor::_safepoint_check_sometimes || is_sometimes_ok(name),
+  assert(_safepoint_check_required != Mutex::_safepoint_check_sometimes || is_sometimes_ok(name),
          "Lock has _safepoint_check_sometimes %s", name);
 #endif
 }
 
-Mutex::Mutex(int Rank, const char * name, bool allow_vm_block,
+Monitor::Monitor(int Rank, const char * name, bool allow_vm_block,
              SafepointCheckRequired safepoint_check_required) :
-  Monitor(Rank, name, allow_vm_block, safepoint_check_required) {}
+  Mutex(Rank, name, allow_vm_block, safepoint_check_required) {}
 
-bool Monitor::owned_by_self() const {
+bool Mutex::owned_by_self() const {
   return _owner == Thread::current();
 }
 
-void Monitor::print_on_error(outputStream* st) const {
+void Mutex::print_on_error(outputStream* st) const {
   st->print("[" PTR_FORMAT, p2i(this));
   st->print("] %s", _name);
   st->print(" - owner thread: " PTR_FORMAT, p2i(_owner));
@@ -278,7 +278,7 @@ void Monitor::print_on_error(outputStream* st) const {
 // Non-product code
 
 #ifndef PRODUCT
-void Monitor::print_on(outputStream* st) const {
+void Mutex::print_on(outputStream* st) const {
   st->print_cr("Mutex: [" PTR_FORMAT "] %s - owner: " PTR_FORMAT,
                p2i(this), _name, p2i(_owner));
 }
@@ -287,7 +287,7 @@ void Monitor::print_on(outputStream* st) const {
 #ifndef PRODUCT
 #ifdef ASSERT
 
-void Monitor::assert_owner(Thread * expected) {
+void Mutex::assert_owner(Thread * expected) {
   const char* msg = "invalid owner";
   if (expected == NULL) {
     msg = "should be un-owned";
@@ -300,8 +300,8 @@ void Monitor::assert_owner(Thread * expected) {
          msg, p2i(_owner), p2i(expected));
 }
 
-Monitor * Monitor::get_least_ranked_lock(Monitor * locks) {
-  Monitor *res, *tmp;
+Mutex* Mutex::get_least_ranked_lock(Mutex* locks) {
+  Mutex *res, *tmp;
   for (res = tmp = locks; tmp != NULL; tmp = tmp->next()) {
     if (tmp->rank() < res->rank()) {
       res = tmp;
@@ -320,8 +320,8 @@ Monitor * Monitor::get_least_ranked_lock(Monitor * locks) {
   return res;
 }
 
-Monitor* Monitor::get_least_ranked_lock_besides_this(Monitor* locks) {
-  Monitor *res, *tmp;
+Mutex* Mutex::get_least_ranked_lock_besides_this(Mutex* locks) {
+  Mutex *res, *tmp;
   for (res = NULL, tmp = locks; tmp != NULL; tmp = tmp->next()) {
     if (tmp != this && (res == NULL || tmp->rank() < res->rank())) {
       res = tmp;
@@ -341,7 +341,7 @@ Monitor* Monitor::get_least_ranked_lock_besides_this(Monitor* locks) {
 }
 
 
-bool Monitor::contains(Monitor* locks, Monitor * lock) {
+bool Mutex::contains(Mutex* locks, Mutex* lock) {
   for (; locks != NULL; locks = locks->next()) {
     if (locks == lock) {
       return true;
@@ -356,7 +356,7 @@ bool Monitor::contains(Monitor* locks, Monitor * lock) {
 // might indicate exposure to deadlock.
 // Rather like an EventListener for _owner (:>).
 
-void Monitor::set_owner_implementation(Thread *new_owner) {
+void Mutex::set_owner_implementation(Thread *new_owner) {
   // This function is solely responsible for maintaining
   // and checking the invariant that threads and locks
   // are in a 1/N relation, with some some locks unowned.
@@ -377,7 +377,7 @@ void Monitor::set_owner_implementation(Thread *new_owner) {
     // link "this" into the owned locks list
 
 #ifdef ASSERT  // Thread::_owned_locks is under the same ifdef
-    Monitor* locks = get_least_ranked_lock(new_owner->owned_locks());
+    Mutex* locks = get_least_ranked_lock(new_owner->owned_locks());
     // Mutex::set_owner_implementation is a friend of Thread
 
     assert(this->rank() >= 0, "bad lock rank");
@@ -415,11 +415,11 @@ void Monitor::set_owner_implementation(Thread *new_owner) {
     _owner = NULL; // set the owner
 
 #ifdef ASSERT
-    Monitor *locks = old_owner->owned_locks();
+    Mutex* locks = old_owner->owned_locks();
 
     // remove "this" from the owned locks list
 
-    Monitor *prev = NULL;
+    Mutex* prev = NULL;
     bool found = false;
     for (; locks != NULL; prev = locks, locks = locks->next()) {
       if (locks == this) {
@@ -440,7 +440,7 @@ void Monitor::set_owner_implementation(Thread *new_owner) {
 
 
 // Factored out common sanity checks for locking mutex'es. Used by lock() and try_lock()
-void Monitor::check_prelock_state(Thread *thread, bool safepoint_check) {
+void Mutex::check_prelock_state(Thread *thread, bool safepoint_check) {
   if (safepoint_check) {
     assert((!thread->is_active_Java_thread() || ((JavaThread *)thread)->thread_state() == _thread_in_vm)
            || rank() == Mutex::special, "wrong thread state for using locks");
@@ -454,13 +454,13 @@ void Monitor::check_prelock_state(Thread *thread, bool safepoint_check) {
          "locking not allowed when crash protection is set");
 }
 
-void Monitor::check_block_state(Thread *thread) {
+void Mutex::check_block_state(Thread *thread) {
   if (!_allow_vm_block && thread->is_VM_thread()) {
     warning("VM thread blocked on lock");
     print();
     BREAKPOINT;
   }
-  assert(_owner != thread, "deadlock: blocking on monitor owned by current thread");
+  assert(_owner != thread, "deadlock: blocking on mutex owned by current thread");
 }
 
 #endif // PRODUCT