src/paimon/common/io/offset_input_stream.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 <functional>
#include <memory>
#include <string>

#include "paimon/fs/file_system.h"
#include "paimon/result.h"
#include "paimon/status.h"
#include "paimon/visibility.h"

namespace paimon {
/// An `InputStream` wrapping another `InputStream` with offset and length.
/// @note Not safe for concurrent or interleaved use with other views of the wrapped stream: Seek
/// and sequential Read share the wrapped stream's position and may read from the wrong offset.
class PAIMON_EXPORT OffsetInputStream : public InputStream {
 public:
    static Result<std::unique_ptr<OffsetInputStream>> Create(
        const std::shared_ptr<InputStream>& wrapped, int64_t length, int64_t offset);
    static Result<std::unique_ptr<OffsetInputStream>> Create(
        const std::shared_ptr<InputStream>& wrapped, int64_t length, int64_t offset,
        int64_t total_length);
    ~OffsetInputStream() override = default;

    Status Seek(int64_t offset, SeekOrigin origin) override;

    Result<int64_t> GetPos() const override;

    Result<int64_t> Read(char* buffer, int64_t size) override;

    Result<int64_t> Read(char* buffer, int64_t size, int64_t offset) override;

    void ReadAsync(char* buffer, int64_t size, int64_t offset,
                   std::function<void(Status)>&& callback) override;

    Result<int64_t> Length() const override;

    Status Close() override;

    Result<std::string> GetUri() const override;

 private:
    OffsetInputStream(const std::shared_ptr<InputStream>& wrapped, int64_t length, int64_t offset);
    Status AssertBoundary(int64_t inner_pos) const;

 private:
    std::shared_ptr<InputStream> wrapped_;
    const int64_t length_;
    const int64_t offset_;
    int64_t inner_position_ = 0;
};
}  // namespace paimon