/*
 * Copyright (C) 2015 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 "jni.h"

#include <iostream>

#include "art_method.h"
#include "base/casts.h"
#include "class_linker.h"
#include "jit/jit.h"
#include "linear_alloc-inl.h"
#include "nativehelper/ScopedUtfChars.h"
#include "runtime.h"
#include "scoped_thread_state_change-inl.h"
#include "thread-current-inl.h"

namespace art {
namespace {

class FindPointerAllocatorVisitor : public AllocatorVisitor {
 public:
  explicit FindPointerAllocatorVisitor(void* ptr) : is_found(false), ptr_(ptr) {}

  bool Visit(LinearAlloc* alloc)
      REQUIRES_SHARED(Locks::classlinker_classes_lock_, Locks::mutator_lock_) override {
    is_found = alloc->Contains(ptr_);
    return !is_found;
  }

  bool is_found;

 private:
  void* ptr_;
};

extern "C" JNIEXPORT jlong JNICALL Java_Main_getArtMethod(JNIEnv* env,
                                                          jclass,
                                                          jobject java_method) {
  ScopedObjectAccess soa(env);
  ArtMethod* method = ArtMethod::FromReflectedMethod(soa, java_method);
  return reinterpret_cast64<jlong>(method);
}

extern "C" JNIEXPORT void JNICALL Java_Main_reuseArenaOfMethod(JNIEnv*,
                                                               jclass,
                                                               jlong art_method) {
  void* ptr = reinterpret_cast64<void*>(art_method);

  ReaderMutexLock mu(Thread::Current(), *Locks::mutator_lock_);
  ReaderMutexLock mu2(Thread::Current(), *Locks::classlinker_classes_lock_);
  // Check if the arena was already implicitly reused by boot classloader.
  if (Runtime::Current()->GetLinearAlloc()->Contains(ptr)) {
    return;
  }

  // Check if the arena was already implicitly reused by some other classloader.
  FindPointerAllocatorVisitor visitor(ptr);
  Runtime::Current()->GetClassLinker()->VisitAllocators(&visitor);
  if (visitor.is_found) {
    return;
  }

  // The arena was not reused yet. Do it explicitly.
  // Create a new allocation and use it to request new arenas until one of them is
  // a reused one that covers the art_method pointer.
  std::unique_ptr<LinearAlloc> alloc(Runtime::Current()->CreateLinearAlloc());
  do {
    // Ask for a word - it's sufficient to get an arena.
    alloc->Alloc(Thread::Current(), sizeof(void*), LinearAllocKind::kNoGCRoots);
  } while (!alloc->Contains(ptr));
}

}  // namespace
}  // namespace art