compiler/dex/quick/dex_file_to_method_inliner_map.cc

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <algorithm>
#include <utility>
#include "thread.h"
#include "thread-inl.h"
#include "base/mutex.h"
#include "base/mutex-inl.h"
#include "base/logging.h"
#include "driver/compiler_driver.h"

#include "dex_file_to_method_inliner_map.h"

namespace art {

DexFileToMethodInlinerMap::DexFileToMethodInlinerMap()
    : lock_("DexFileToMethodInlinerMap lock", kDexFileToMethodInlinerMapLock) {
}

DexFileToMethodInlinerMap::~DexFileToMethodInlinerMap() {
  for (auto& entry : inliners_) {
    delete entry.second;
  }
}

DexFileMethodInliner* DexFileToMethodInlinerMap::GetMethodInliner(const DexFile* dex_file) {
  Thread* self = Thread::Current();
  {
    ReaderMutexLock mu(self, lock_);
    auto it = inliners_.find(dex_file);
    if (it != inliners_.end()) {
      return it->second;
    }
  }

  // We need to acquire our lock_ to modify inliners_ but we want to release it
  // before we initialize the new inliner. However, we need to acquire the
  // new inliner's lock_ before we release our lock_ to prevent another thread
  // from using the uninitialized inliner. This requires explicit calls to
  // ExclusiveLock()/ExclusiveUnlock() on one of the locks, the other one
  // can use WriterMutexLock.
  DexFileMethodInliner* locked_inliner;
  {
    WriterMutexLock mu(self, lock_);
    DexFileMethodInliner** inliner = &inliners_[dex_file];  // inserts new entry if not found
    if (*inliner) {
      return *inliner;
    }
    *inliner = new DexFileMethodInliner;
    DCHECK(*inliner != nullptr);
    locked_inliner = *inliner;
    locked_inliner->lock_.ExclusiveLock(self);  // Acquire inliner's lock_ before releasing lock_.
  }
  locked_inliner->FindIntrinsics(dex_file);
  locked_inliner->lock_.ExclusiveUnlock(self);
  return locked_inliner;
}

}  // namespace art