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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_BUFFER_WITH_EXTENDABLE_BUFFER_H
#define LATINIME_BUFFER_WITH_EXTENDABLE_BUFFER_H
#include <cstddef>
#include <cstdint>
#include <vector>
#include "defines.h"
#include "dictionary/utils/byte_array_utils.h"
#include "utils/byte_array_view.h"
namespace latinime {
// This is used as a buffer that can be extended for updatable dictionaries.
// To optimize performance, raw pointer is directly used for reading buffer. The position has to be
// adjusted to access additional buffer. On the other hand, this class does not provide writable
// raw pointer but provides several methods that handle boundary checking for writing data.
class BufferWithExtendableBuffer {
public:
static const size_t DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE;
BufferWithExtendableBuffer(const ReadWriteByteArrayView originalBuffer,
const int maxAdditionalBufferSize)
: mOriginalBuffer(originalBuffer), mAdditionalBuffer(), mUsedAdditionalBufferSize(0),
mMaxAdditionalBufferSize(maxAdditionalBufferSize) {}
// Without original buffer.
BufferWithExtendableBuffer(const int maxAdditionalBufferSize)
: mOriginalBuffer(), mAdditionalBuffer(), mUsedAdditionalBufferSize(0),
mMaxAdditionalBufferSize(maxAdditionalBufferSize) {}
AK_FORCE_INLINE int getTailPosition() const {
return mOriginalBuffer.size() + mUsedAdditionalBufferSize;
}
AK_FORCE_INLINE int getUsedAdditionalBufferSize() const {
return mUsedAdditionalBufferSize;
}
/**
* For reading.
*/
AK_FORCE_INLINE bool isInAdditionalBuffer(const int position) const {
return position >= static_cast<int>(mOriginalBuffer.size());
}
// TODO: Resolve the issue that the address can be changed when the vector is resized.
// CAVEAT!: Be careful about array out of bound access with buffers
AK_FORCE_INLINE const uint8_t *getBuffer(const bool usesAdditionalBuffer) const {
if (usesAdditionalBuffer) {
return mAdditionalBuffer.data();
} else {
return mOriginalBuffer.data();
}
}
uint32_t readUint(const int size, const int pos) const;
uint32_t readUintAndAdvancePosition(const int size, int *const pos) const;
void readCodePointsAndAdvancePosition(const int maxCodePointCount,
int *const outCodePoints, int *outCodePointCount, int *const pos) const;
AK_FORCE_INLINE int getOriginalBufferSize() const {
return mOriginalBuffer.size();
}
AK_FORCE_INLINE bool isNearSizeLimit() const {
return mAdditionalBuffer.size() >= ((mMaxAdditionalBufferSize
* NEAR_BUFFER_LIMIT_THRESHOLD_PERCENTILE) / 100);
}
bool extend(const int size);
/**
* For writing.
*
* Writing is allowed for original buffer, already written region of additional buffer and the
* tail of additional buffer.
*/
bool writeUint(const uint32_t data, const int size, const int pos);
bool writeUintAndAdvancePosition(const uint32_t data, const int size, int *const pos);
bool writeCodePointsAndAdvancePosition(const int *const codePoints, const int codePointCount,
const bool writesTerminator, int *const pos);
bool copy(const BufferWithExtendableBuffer *const sourceBuffer);
private:
DISALLOW_COPY_AND_ASSIGN(BufferWithExtendableBuffer);
static const int NEAR_BUFFER_LIMIT_THRESHOLD_PERCENTILE;
static const size_t EXTEND_ADDITIONAL_BUFFER_SIZE_STEP;
const ReadWriteByteArrayView mOriginalBuffer;
std::vector<uint8_t> mAdditionalBuffer;
int mUsedAdditionalBufferSize;
const size_t mMaxAdditionalBufferSize;
// Return if the buffer is successfully extended or not.
bool extendBuffer(const size_t size);
// Returns if it is possible to write size-bytes from pos. When pos is at the tail position of
// the additional buffer, try extending the buffer.
bool checkAndPrepareWriting(const int pos, const int size);
};
}
#endif /* LATINIME_BUFFER_WITH_EXTENDABLE_BUFFER_H */
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