be/src/io/fs/s3_common.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 <aws/core/utils/memory/stl/AWSStreamFwd.h>
#include <aws/core/utils/stream/PreallocatedStreamBuf.h>

namespace doris {

// A non-copying iostream.
// See https://stackoverflow.com/questions/35322033/aws-c-sdk-uploadpart-times-out
// https://stackoverflow.com/questions/13059091/creating-an-input-stream-from-constant-memory
class StringViewStream : Aws::Utils::Stream::PreallocatedStreamBuf, public std::iostream {
public:
    StringViewStream(const void* buf, int64_t nbytes)
            : Aws::Utils::Stream::PreallocatedStreamBuf(
                      reinterpret_cast<unsigned char*>(const_cast<void*>(buf)),
                      static_cast<size_t>(nbytes)),
              std::iostream(this) {}
};

// By default, the AWS SDK reads object data into an auto-growing StringStream.
// To avoid copies, read directly into our preallocated buffer instead.
// See https://github.com/aws/aws-sdk-cpp/issues/64 for an alternative but
// functionally similar recipe.
inline Aws::IOStreamFactory AwsWriteableStreamFactory(void* buf, int64_t nbytes) {
    return [=]() { return Aws::New<StringViewStream>("", buf, nbytes); };
}

} // namespace doris