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/*
* 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.
*/
#ifndef LATINIME_EXCLUSIVE_OWNERSHIP_POINTER_H
#define LATINIME_EXCLUSIVE_OWNERSHIP_POINTER_H
#include "defines.h"
namespace latinime {
template<class T>
class ExclusiveOwnershipPointer {
public:
// This instance become an owner of the raw pointer.
ExclusiveOwnershipPointer(T *const rawPointer)
: mPointer(rawPointer),
mSharedOwnerPtr(new (ExclusiveOwnershipPointer<T> *)(this)) {}
// Move the ownership.
ExclusiveOwnershipPointer(const ExclusiveOwnershipPointer<T> &pointer)
: mPointer(pointer.mPointer), mSharedOwnerPtr(pointer.mSharedOwnerPtr) {
transferOwnership(&pointer);
}
~ExclusiveOwnershipPointer() {
deletePointersIfHavingOwnership();
}
// Move the ownership.
ExclusiveOwnershipPointer<T> &operator=(const ExclusiveOwnershipPointer<T> &pointer) {
// Delete pointers when this is an owner of another pointer.
deletePointersIfHavingOwnership();
mPointer = pointer.mPointer;
mSharedOwnerPtr = pointer.mSharedOwnerPtr;
transferOwnership(pointer);
return *this;
}
T *get() const {
return mPointer;
}
private:
// This class allows to copy and assign and ensures only one instance has the ownership of the
// managed pointer.
ExclusiveOwnershipPointer() : mPointer(0), mSharedOwnerPtr(0) {}
void transferOwnership(const ExclusiveOwnershipPointer<T> *const src) {
if (*mSharedOwnerPtr != src) {
AKLOGE("Failed to transfer the ownership because src is not the current owner."
"src: %p, owner: %p", src, *mSharedOwnerPtr);
ASSERT(false);
return;
}
// Transfer the ownership from src to this instance.
*mSharedOwnerPtr = this;
}
void deletePointersIfHavingOwnership() {
if (mSharedOwnerPtr && *mSharedOwnerPtr == this) {
if (mPointer) {
if (DEBUG_DICT) {
AKLOGI("Releasing pointer: %p", mPointer);
}
delete mPointer;
}
delete mSharedOwnerPtr;
}
}
T *mPointer;
// mSharedOwnerPtr points a shared memory space where the instance which has the ownership is
// stored.
ExclusiveOwnershipPointer<T> **mSharedOwnerPtr;
};
} // namespace latinime
#endif /* LATINIME_EXCLUSIVE_OWNERSHIP_POINTER_H */
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