ClickHouse/dbms/IO/ReadBufferFromS3.cpp

#include <Common/config.h>

#if USE_AWS_S3

#    include <IO/ReadBufferFromIStream.h>
#    include <IO/ReadBufferFromS3.h>

#    include <aws/s3/S3Client.h>
#    include <aws/s3/model/GetObjectRequest.h>
#    include <common/logger_useful.h>

#    include <utility>

namespace DB
{
namespace ErrorCodes
{
    extern const int S3_ERROR;
    extern const int CANNOT_SEEK_THROUGH_FILE;
    extern const int SEEK_POSITION_OUT_OF_BOUND;
}


ReadBufferFromS3::ReadBufferFromS3(
    std::shared_ptr<Aws::S3::S3Client> client_ptr_, const String & bucket_, const String & key_, size_t buffer_size_)
    : SeekableReadBuffer(nullptr, 0), client_ptr(std::move(client_ptr_)), bucket(bucket_), key(key_), buffer_size(buffer_size_)
{
}

bool ReadBufferFromS3::nextImpl()
{
    if (!initialized)
    {
        impl = initialize();
        initialized = true;
    }

    if (!impl->next())
        return false;
    internal_buffer = impl->buffer();
    working_buffer = internal_buffer;
    return true;
}

off_t ReadBufferFromS3::seek(off_t offset_, int whence)
{
    if (initialized)
        throw Exception("Seek is allowed only before first read attempt from the buffer.", ErrorCodes::CANNOT_SEEK_THROUGH_FILE);

    if (whence != SEEK_SET)
        throw Exception("Only SEEK_SET mode is allowed.", ErrorCodes::CANNOT_SEEK_THROUGH_FILE);

    if (offset_ < 0)
        throw Exception("Seek position is out of bounds. Offset: " + std::to_string(offset_), ErrorCodes::SEEK_POSITION_OUT_OF_BOUND);

    offset = offset_;

    return offset;
}


off_t ReadBufferFromS3::getPosition()
{
    return offset + count();
}

std::unique_ptr<ReadBuffer> ReadBufferFromS3::initialize()
{
    LOG_TRACE(log, "Read S3 object. Bucket: " + bucket + ", Key: " + key + ", Offset: " + std::to_string(offset));

    Aws::S3::Model::GetObjectRequest req;
    req.SetBucket(bucket);
    req.SetKey(key);
    if (offset != 0)
        req.SetRange("bytes=" + std::to_string(offset) + "-");

    Aws::S3::Model::GetObjectOutcome outcome = client_ptr->GetObject(req);

    if (outcome.IsSuccess())
    {
        read_result = outcome.GetResultWithOwnership();
        return std::make_unique<ReadBufferFromIStream>(read_result.GetBody(), buffer_size);
    }
    else
        throw Exception(outcome.GetError().GetMessage(), ErrorCodes::S3_ERROR);
}

}

#endif