c++ - Azure C++ 库 : "Invalid streambuf object"

Question

我正在尝试使用 C++ Azure 客户端库下载一个可能巨大的 Azure block blob。它不起作用，因为我不知道如何使用缓冲区大小初始化 concurrency::streams::streambuf 对象。我的代码如下所示:

 // Assume blockBlob has been created correctly.
 concurrency::streams::istream blobStream = blockBlob.open_read();
 // I don't know how to initialize this streambuf:         
 concurrency::streams::streambuf<uint8_t> dlStreamBuf;
 size_t nBytesReturned = 0, nBytesToRead = 65536;
 do {
    // This gets the exception "Invalid streambuf object": 
    concurrency::task<size_t> returnedTask = blobStream.read(dlStreamBuf, nBytesToRead);
    nBytesReturned = returnedTask.get();
    bytesSoFar += nBytesReturned;
    // Process the data in dlStreamBuf here...
 } while(nBytesReturned > 0);
 blobStream.close();

请注意，不要将上述 Streambuf 与标准 C++ Streambuf 混淆。

任何人都可以告诉我如何正确构造和初始化 concurrency::streams::streambuf 吗？

谢谢。

Answer 1

streambuf 似乎是一个模板类。试试这个:

    concurrency::streams::container_buffer<std::vector<uint8_t>> output_buffer;
    size_t nBytesReturned = 0, nBytesToRead = 65536;
    do {
        // This gets the exception "Invalid streambuf object": 
        concurrency::task<size_t> returnedTask = stream.read(output_buffer, nBytesToRead);
        nBytesReturned = returnedTask.get();
        bytesSoFar += nBytesReturned;
        // Process the data in dlStreamBuf here...
    } while (nBytesReturned > 0);
    stream.close();

示例代码在这里:https://github.com/Azure/azure-storage-cpp/blob/76cb553249ede1e6f05456d936c9a36753cc1597/Microsoft.WindowsAzure.Storage/tests/blob_streams_test.cpp#L192