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 #include "base/macros.h"
25 
26 namespace art HIDDEN {
27 
28 namespace mirror {
29 class Object;
30 }  // namespace mirror
31 
32 class Thread;
33 
34 // Counting locks by storing object pointers into a vector. Duplicate entries mark recursive locks.
35 // The vector will be visited with the ShadowFrame during GC (so all the locked-on objects are
36 // thread roots).
37 // Note: implementation is split so that the call sites may be optimized to no-ops in case no
38 //       lock counting is necessary. The actual implementation is in the cc file to avoid
39 //       dependencies.
40 class LockCountData {
41  public:
42   // Add the given object to the list of monitors, that is, objects that have been locked. This
43   // will not throw (but be skipped if there is an exception pending on entry).
44   void AddMonitor(Thread* self, mirror::Object* obj) REQUIRES_SHARED(Locks::mutator_lock_);
45 
46   // Try to remove the given object from the monitor list, indicating an unlock operation.
47   // This will throw an IllegalMonitorStateException (clearing any already pending exception), in
48   // case that there wasn't a lock recorded for the object.
49   void RemoveMonitorOrThrow(Thread* self,
50                             const mirror::Object* obj) REQUIRES_SHARED(Locks::mutator_lock_);
51 
52   // Check whether all acquired monitors have been released. This will potentially throw an
53   // IllegalMonitorStateException, clearing any already pending exception. Returns true if the
54   // check shows that everything is OK wrt/ lock counting, false otherwise.
55   bool CheckAllMonitorsReleasedOrThrow(Thread* self) REQUIRES_SHARED(Locks::mutator_lock_);
56 
57   template <typename T, typename... Args>
VisitMonitors(T visitor,Args &&...args)58   void VisitMonitors(T visitor, Args&&... args) REQUIRES_SHARED(Locks::mutator_lock_) {
59     if (monitors_ != nullptr) {
60       // Visitors may change the Object*. Be careful with the foreach loop.
61       for (mirror::Object*& obj : *monitors_) {
62         visitor(/* inout */ &obj, std::forward<Args>(args)...);
63       }
64     }
65   }
66 
67  private:
68   // Stores references to the locked-on objects. As noted, this should be visited during thread
69   // marking.
70   std::unique_ptr<std::vector<mirror::Object*>> monitors_;
71 };
72 
73 }  // namespace art
74 
75 #endif  // ART_RUNTIME_INTERPRETER_LOCK_COUNT_DATA_H_
76