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      1 /*
      2  * Copyright (C) 2013 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 #include <algorithm>
     18 #include <utility>
     19 #include "thread.h"
     20 #include "thread-inl.h"
     21 #include "base/mutex.h"
     22 #include "base/mutex-inl.h"
     23 #include "base/logging.h"
     24 #include "driver/compiler_driver.h"
     25 
     26 #include "dex_file_to_method_inliner_map.h"
     27 
     28 namespace art {
     29 
     30 DexFileToMethodInlinerMap::DexFileToMethodInlinerMap()
     31     : lock_("DexFileToMethodInlinerMap lock", kDexFileToMethodInlinerMapLock) {
     32 }
     33 
     34 DexFileToMethodInlinerMap::~DexFileToMethodInlinerMap() {
     35   for (auto& entry : inliners_) {
     36     delete entry.second;
     37   }
     38 }
     39 
     40 DexFileMethodInliner* DexFileToMethodInlinerMap::GetMethodInliner(const DexFile* dex_file) {
     41   Thread* self = Thread::Current();
     42   {
     43     ReaderMutexLock mu(self, lock_);
     44     auto it = inliners_.find(dex_file);
     45     if (it != inliners_.end()) {
     46       return it->second;
     47     }
     48   }
     49 
     50   // We need to acquire our lock_ to modify inliners_ but we want to release it
     51   // before we initialize the new inliner. However, we need to acquire the
     52   // new inliner's lock_ before we release our lock_ to prevent another thread
     53   // from using the uninitialized inliner. This requires explicit calls to
     54   // ExclusiveLock()/ExclusiveUnlock() on one of the locks, the other one
     55   // can use WriterMutexLock.
     56   DexFileMethodInliner* locked_inliner;
     57   {
     58     WriterMutexLock mu(self, lock_);
     59     DexFileMethodInliner** inliner = &inliners_[dex_file];  // inserts new entry if not found
     60     if (*inliner) {
     61       return *inliner;
     62     }
     63     *inliner = new DexFileMethodInliner;
     64     DCHECK(*inliner != nullptr);
     65     locked_inliner = *inliner;
     66     locked_inliner->lock_.ExclusiveLock(self);  // Acquire inliner's lock_ before releasing lock_.
     67   }
     68   locked_inliner->FindIntrinsics(dex_file);
     69   locked_inliner->lock_.ExclusiveUnlock(self);
     70   return locked_inliner;
     71 }
     72 
     73 }  // namespace art
     74