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      1 /*
      2  * Copyright (C) 2012 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_NTH_CALLER_VISITOR_H_
     18 #define ART_RUNTIME_NTH_CALLER_VISITOR_H_
     19 
     20 #include "art_method.h"
     21 #include "base/mutex.h"
     22 #include "stack.h"
     23 
     24 namespace art {
     25 class Thread;
     26 
     27 // Walks up the stack 'n' callers, when used with Thread::WalkStack.
     28 struct NthCallerVisitor : public StackVisitor {
     29   NthCallerVisitor(Thread* thread, size_t n_in, bool include_runtime_and_upcalls = false)
     30       : StackVisitor(thread, nullptr, StackVisitor::StackWalkKind::kIncludeInlinedFrames),
     31         n(n_in),
     32         include_runtime_and_upcalls_(include_runtime_and_upcalls),
     33         count(0),
     34         caller(nullptr) {}
     35 
     36   bool VisitFrame() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     37     ArtMethod* m = GetMethod();
     38     bool do_count = false;
     39     if (m == nullptr || m->IsRuntimeMethod()) {
     40       // Upcall.
     41       do_count = include_runtime_and_upcalls_;
     42     } else {
     43       do_count = true;
     44     }
     45     if (do_count) {
     46       DCHECK(caller == nullptr);
     47       if (count == n) {
     48         caller = m;
     49         return false;
     50       }
     51       count++;
     52     }
     53     return true;
     54   }
     55 
     56   const size_t n;
     57   const bool include_runtime_and_upcalls_;
     58   size_t count;
     59   ArtMethod* caller;
     60 };
     61 
     62 }  // namespace art
     63 
     64 #endif  // ART_RUNTIME_NTH_CALLER_VISITOR_H_
     65