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      1 /*
      2  * Copyright (C) 2014 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_MONITOR_OBJECTS_STACK_VISITOR_H_
     18 #define ART_RUNTIME_MONITOR_OBJECTS_STACK_VISITOR_H_
     19 
     20 #include <android-base/logging.h>
     21 
     22 #include "art_method.h"
     23 #include "base/mutex.h"
     24 #include "monitor.h"
     25 #include "stack.h"
     26 #include "thread.h"
     27 #include "thread_state.h"
     28 
     29 namespace art {
     30 
     31 namespace mirror {
     32 class Object;
     33 }
     34 
     35 class Context;
     36 
     37 class MonitorObjectsStackVisitor : public StackVisitor {
     38  public:
     39   MonitorObjectsStackVisitor(Thread* thread_in,
     40                              Context* context,
     41                              bool check_suspended = true,
     42                              bool dump_locks_in = true)
     43       REQUIRES_SHARED(Locks::mutator_lock_)
     44       : StackVisitor(thread_in,
     45                      context,
     46                      StackVisitor::StackWalkKind::kIncludeInlinedFrames,
     47                      check_suspended),
     48         frame_count(0u),
     49         dump_locks(dump_locks_in) {}
     50 
     51   enum class VisitMethodResult {
     52     kContinueMethod,
     53     kSkipMethod,
     54     kEndStackWalk,
     55   };
     56 
     57   bool VisitFrame() FINAL REQUIRES_SHARED(Locks::mutator_lock_) {
     58     ArtMethod* m = GetMethod();
     59     if (m->IsRuntimeMethod()) {
     60       return true;
     61     }
     62 
     63     VisitMethodResult vmrEntry = StartMethod(m, frame_count);
     64     switch (vmrEntry) {
     65       case VisitMethodResult::kContinueMethod:
     66         break;
     67       case VisitMethodResult::kSkipMethod:
     68         return true;
     69       case VisitMethodResult::kEndStackWalk:
     70         return false;
     71     }
     72 
     73     if (frame_count == 0) {
     74       // Top frame, check for blocked state.
     75 
     76       mirror::Object* monitor_object;
     77       uint32_t lock_owner_tid;
     78       ThreadState state = Monitor::FetchState(GetThread(),
     79                                               &monitor_object,
     80                                               &lock_owner_tid);
     81       switch (state) {
     82         case kWaiting:
     83         case kTimedWaiting:
     84           VisitWaitingObject(monitor_object, state);
     85           break;
     86         case kSleeping:
     87           VisitSleepingObject(monitor_object);
     88           break;
     89 
     90         case kBlocked:
     91         case kWaitingForLockInflation:
     92           VisitBlockedOnObject(monitor_object, state, lock_owner_tid);
     93           break;
     94 
     95         default:
     96           break;
     97       }
     98     }
     99 
    100     if (dump_locks) {
    101       // Visit locks, but do not abort on errors. This could trigger a nested abort.
    102       // Skip visiting locks if dump_locks is false as it would cause a bad_mutexes_held in
    103       // RegTypeCache::RegTypeCache due to thread_list_lock.
    104       Monitor::VisitLocks(this, VisitLockedObject, this, false);
    105     }
    106 
    107     ++frame_count;
    108 
    109     VisitMethodResult vmrExit = EndMethod(m);
    110     switch (vmrExit) {
    111       case VisitMethodResult::kContinueMethod:
    112       case VisitMethodResult::kSkipMethod:
    113         return true;
    114 
    115       case VisitMethodResult::kEndStackWalk:
    116         return false;
    117     }
    118     LOG(FATAL) << "Unreachable";
    119     UNREACHABLE();
    120   }
    121 
    122  protected:
    123   virtual VisitMethodResult StartMethod(ArtMethod* m, size_t frame_nr)
    124       REQUIRES_SHARED(Locks::mutator_lock_) = 0;
    125   virtual VisitMethodResult EndMethod(ArtMethod* m)
    126       REQUIRES_SHARED(Locks::mutator_lock_) = 0;
    127 
    128   virtual void VisitWaitingObject(mirror::Object* obj, ThreadState state)
    129       REQUIRES_SHARED(Locks::mutator_lock_) = 0;
    130   virtual void VisitSleepingObject(mirror::Object* obj)
    131       REQUIRES_SHARED(Locks::mutator_lock_) = 0;
    132   virtual void VisitBlockedOnObject(mirror::Object* obj, ThreadState state, uint32_t owner_tid)
    133       REQUIRES_SHARED(Locks::mutator_lock_) = 0;
    134   virtual void VisitLockedObject(mirror::Object* obj)
    135       REQUIRES_SHARED(Locks::mutator_lock_) = 0;
    136 
    137   size_t frame_count;
    138 
    139  private:
    140   static void VisitLockedObject(mirror::Object* o, void* context)
    141       REQUIRES_SHARED(Locks::mutator_lock_) {
    142     MonitorObjectsStackVisitor* self = reinterpret_cast<MonitorObjectsStackVisitor*>(context);
    143     if (o != nullptr) {
    144       if (kUseReadBarrier && Thread::Current()->GetIsGcMarking()) {
    145         // We may call Thread::Dump() in the middle of the CC thread flip and this thread's stack
    146         // may have not been flipped yet and "o" may be a from-space (stale) ref, in which case the
    147         // IdentityHashCode call below will crash. So explicitly mark/forward it here.
    148         o = ReadBarrier::Mark(o);
    149       }
    150     }
    151     self->VisitLockedObject(o);
    152   }
    153 
    154   const bool dump_locks;
    155 };
    156 
    157 }  // namespace art
    158 
    159 #endif  // ART_RUNTIME_MONITOR_OBJECTS_STACK_VISITOR_H_
    160