src/paimon/common/data/abstract_binary_writer.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

#pragma once

#include <cstdint>
#include <optional>
#include <string_view>

#include "paimon/common/data/binary_writer.h"
#include "paimon/common/memory/memory_segment.h"

namespace paimon {
class BinaryArray;
class BinaryRow;
class BinaryString;
class Bytes;
class Decimal;
class MemoryPool;
class Timestamp;

/// Use the special format to write data to a `MemorySegment` (its capacity grows
/// automatically). If write a format binary: 1. New a writer. 2. Write each field by `WriteXXX()`
/// or `SetNullAt()`. (Variable length fields can not be written repeatedly.) 3. Invoke
/// `Complete()`. If want to reuse this writer, please invoke `Reset()` first.
class AbstractBinaryWriter : public BinaryWriter {
 public:
    void WriteString(int32_t pos, const BinaryString& value) override;

    void WriteBinary(int32_t pos, const Bytes& bytes) override;

    void WriteDecimal(int32_t pos, const std::optional<Decimal>& value, int32_t precision) override;

    void WriteTimestamp(int32_t pos, const std::optional<Timestamp>& value,
                        int32_t precision) override;

    void WriteArray(int32_t pos, const BinaryArray& value) override;

    void WriteRow(int32_t pos, const BinaryRow& value) override;

    void WriteMap(int32_t pos, const BinaryMap& input) override;

    void WriteStringView(int32_t pos, const std::string_view& view) override;

    const MemorySegment& GetSegment() const {
        return segment_;
    }

 protected:
    static int32_t RoundNumberOfBytesToNearestWord(int32_t num_bytes);

    /// Set offset and size to fix len part.
    virtual void SetOffsetAndSize(int32_t pos, int32_t offset, int64_t size) = 0;

    /// Get field offset.
    virtual int32_t GetFieldOffset(int32_t pos) const = 0;

    /// After grow, need point to new memory.
    virtual void AfterGrow() = 0;

    virtual void SetNullBit(int32_t ordinal) = 0;

    void ZeroOutPaddingBytes(int32_t num_bytes);
    void EnsureCapacity(int32_t needed_size);

 private:
    /// Increases the capacity to ensure that it can hold at least the minimum capacity argument.
    void Grow(int32_t min_capacity);

    void WriteBytes(int32_t pos, const Bytes& bytes);

    template <typename T>
    void WriteBytesToVarLenPart(int32_t pos, const T& bytes, int32_t len);

    template <typename T>
    static void WriteBytesToFixLenPart(MemorySegment* segment, int32_t field_offset, const T& bytes,
                                       int32_t len);

    void WriteSegmentToVarLenPart(int32_t pos, const MemorySegment& segment, int32_t offset,
                                  int32_t size);

 protected:
    int32_t cursor_ = 0;
    MemoryPool* pool_ = nullptr;
    MemorySegment segment_;
};

}  // namespace paimon