Recently I have found an annoying problem with boost:asio::async_read.
When I transfer large amounts of data, say a file of about 9GB, boost:asio::async_read works well in most of the time, but sometimes the completion of async_read is executed with bytes_transferred=0 and ec=0! And sometimes the completion of async_read is executed with bytes_transferred!=sp_recv_data->size() and ec still equal to 0.
My code just like below:
void CNetProactorClientImpl::async_recv()
{
auto sp_vec_buf = make_shared<std::vector<unsigned char>>(1 * 1024 * 1024);
/*
boost::asio::async_read
this function is used to asynchronously read a certain number of bytes of data from a stream.
the function call always returns immediately. the asynchronous operation will continue until one of the following conditions is true:
*the supplied buffers are full. that is, the bytes transferred is equal to the sum of the buffer sizes.
*an error occurred.
*/
boost::asio::async_read(*sp_socket,
boost::asio::buffer(sp_vec_buf),
bind(&CNetProactorClientImpl::async_recv_complete_handler, this,
sp_vec_buf,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
}
void CNetProactorClientImpl::async_recv_complete_handler(shared_ptr<std::vector<unsigned char>> sp_recv_data, const boost::system::error_code& ec, size_t bytes_transferred)
{
if (!ec)
{
//no error
if (bytes_transferred == 0)
{
//Sometimes it trigger here, ec is 0 but also bytes_transferred! Why???
assert(bytes_transferred == sp_recv_data->size());
}
if (bytes_transferred != sp_recv_data->size())
{
/*
Sometimes it trigger here, it is also a strange behavior that bytes_transferred NOT equal to sp_recv_data->size() because the Boost document say:
The asynchronous operation will continue until one of the following conditions is true:
*The supplied buffers are full. That is, the bytes transferred is equal to the sum of the buffer sizes.
*An error occurred.
*/
assert(bytes_transferred == sp_recv_data->size());
}
//do normal action
}
else
{
//error handling
disconnect();
}
}
My boost version is 1.61. Testing environment: win10 pro +VS2015 Update3.
