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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ART_RUNTIME_INTERPRETER_LOCK_COUNT_DATA_H_
     18 #define ART_RUNTIME_INTERPRETER_LOCK_COUNT_DATA_H_
     19 
     20 #include <memory>
     21 #include <vector>
     22 
     23 #include "base/locks.h"
     24 
     25 namespace art {
     26 
     27 namespace mirror {
     28 class Object;
     29 }  // namespace mirror
     30 
     31 class Thread;
     32 
     33 // Counting locks by storing object pointers into a vector. Duplicate entries mark recursive locks.
     34 // The vector will be visited with the ShadowFrame during GC (so all the locked-on objects are
     35 // thread roots).
     36 // Note: implementation is split so that the call sites may be optimized to no-ops in case no
     37 //       lock counting is necessary. The actual implementation is in the cc file to avoid
     38 //       dependencies.
     39 class LockCountData {
     40  public:
     41   // Add the given object to the list of monitors, that is, objects that have been locked. This
     42   // will not throw (but be skipped if there is an exception pending on entry).
     43   void AddMonitor(Thread* self, mirror::Object* obj) REQUIRES_SHARED(Locks::mutator_lock_);
     44 
     45   // Try to remove the given object from the monitor list, indicating an unlock operation.
     46   // This will throw an IllegalMonitorStateException (clearing any already pending exception), in
     47   // case that there wasn't a lock recorded for the object.
     48   void RemoveMonitorOrThrow(Thread* self,
     49                             const mirror::Object* obj) REQUIRES_SHARED(Locks::mutator_lock_);
     50 
     51   // Check whether all acquired monitors have been released. This will potentially throw an
     52   // IllegalMonitorStateException, clearing any already pending exception. Returns true if the
     53   // check shows that everything is OK wrt/ lock counting, false otherwise.
     54   bool CheckAllMonitorsReleasedOrThrow(Thread* self) REQUIRES_SHARED(Locks::mutator_lock_);
     55 
     56   template <typename T, typename... Args>
     57   void VisitMonitors(T visitor, Args&&... args) REQUIRES_SHARED(Locks::mutator_lock_) {
     58     if (monitors_ != nullptr) {
     59       // Visitors may change the Object*. Be careful with the foreach loop.
     60       for (mirror::Object*& obj : *monitors_) {
     61         visitor(/* inout */ &obj, std::forward<Args>(args)...);
     62       }
     63     }
     64   }
     65 
     66  private:
     67   // Stores references to the locked-on objects. As noted, this should be visited during thread
     68   // marking.
     69   std::unique_ptr<std::vector<mirror::Object*>> monitors_;
     70 };
     71 
     72 }  // namespace art
     73 
     74 #endif  // ART_RUNTIME_INTERPRETER_LOCK_COUNT_DATA_H_
     75