Asynchronously writing data from streambuf while appending to it
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I like to implement a "fire and forget" kind of stream where I may asynchronously append data that is to be written during writing. Can asio::streambuf be safely used for that?
asio::streambuf send_buffer;
bool flushing = false;
asio::ip::tcp::socket socket;
// may be called by timers, read handlers, whatever
void new_data_handler(const char* data, size_t size) {
send_buffer.sputn(data, size);
flush();
}
void flush() {
if (flushing || send_buffer.size() == 0) return;
flushing = true;
asio::async_write(socket, send_buffer, [&](auto, auto) {
// error handling
// as per doc data is consumed from the buffer automatically
flushing = false;
flush(); // not sure if this even needs to be called
});
}
While the lifetime of the streambuf itself is clear, I am concerned that adding new data will invalidate any buffers that view into its memory. That would be find if this is isolated to within handlers, but I cannot find any documentation as to whether that is true or not.
It appears that
socket.async_write_some(send_buffer, (auto, auto){});
does not work at all, it would require send_buffer.data() - which would be invalidated by operations on send_buffer as is documented.
I have also considered asio::buffered_write_stream, but it seems that it does not provide a simple way to dump data in a guaranteed non-blocking way.
The underlying sockets are tcp and ssl sockets. All handlers are executed in the same strand.
c++ boost io boost-asio
asked Nov 23 '18 at 13:29
ZulanZulan
16k63373
add a comment |
I like to implement a "fire and forget" kind of stream where I may asynchronously append data that is to be written during writing. Can asio::streambuf be safely used for that?
asio::streambuf send_buffer;
bool flushing = false;
asio::ip::tcp::socket socket;
// may be called by timers, read handlers, whatever
void new_data_handler(const char* data, size_t size) {
send_buffer.sputn(data, size);
flush();
}
void flush() {
if (flushing || send_buffer.size() == 0) return;
flushing = true;
asio::async_write(socket, send_buffer, [&](auto, auto) {
// error handling
// as per doc data is consumed from the buffer automatically
flushing = false;
flush(); // not sure if this even needs to be called
});
}
While the lifetime of the streambuf itself is clear, I am concerned that adding new data will invalidate any buffers that view into its memory. That would be find if this is isolated to within handlers, but I cannot find any documentation as to whether that is true or not.
It appears that
socket.async_write_some(send_buffer, (auto, auto){});
does not work at all, it would require send_buffer.data() - which would be invalidated by operations on send_buffer as is documented.
I have also considered asio::buffered_write_stream, but it seems that it does not provide a simple way to dump data in a guaranteed non-blocking way.
The underlying sockets are tcp and ssl sockets. All handlers are executed in the same strand.
c++ boost io boost-asio
asked Nov 23 '18 at 13:29
ZulanZulan
16k63373
See stackoverflow.com/a/12801042/85371
– sehe
Nov 24 '18 at 15:46
add a comment |
I like to implement a "fire and forget" kind of stream where I may asynchronously append data that is to be written during writing. Can asio::streambuf be safely used for that?
asio::streambuf send_buffer;
bool flushing = false;
asio::ip::tcp::socket socket;
// may be called by timers, read handlers, whatever
void new_data_handler(const char* data, size_t size) {
send_buffer.sputn(data, size);
flush();
}
void flush() {
if (flushing || send_buffer.size() == 0) return;
flushing = true;
asio::async_write(socket, send_buffer, [&](auto, auto) {
// error handling
// as per doc data is consumed from the buffer automatically
flushing = false;
flush(); // not sure if this even needs to be called
});
}
While the lifetime of the streambuf itself is clear, I am concerned that adding new data will invalidate any buffers that view into its memory. That would be find if this is isolated to within handlers, but I cannot find any documentation as to whether that is true or not.
It appears that
socket.async_write_some(send_buffer, (auto, auto){});
does not work at all, it would require send_buffer.data() - which would be invalidated by operations on send_buffer as is documented.
I have also considered asio::buffered_write_stream, but it seems that it does not provide a simple way to dump data in a guaranteed non-blocking way.
The underlying sockets are tcp and ssl sockets. All handlers are executed in the same strand.
c++ boost io boost-asio
asked Nov 23 '18 at 13:29
ZulanZulan
16k63373
I like to implement a "fire and forget" kind of stream where I may asynchronously append data that is to be written during writing. Can asio::streambuf be safely used for that?
asio::streambuf send_buffer;
bool flushing = false;
asio::ip::tcp::socket socket;
// may be called by timers, read handlers, whatever
void new_data_handler(const char* data, size_t size) {
send_buffer.sputn(data, size);
flush();
}
void flush() {
if (flushing || send_buffer.size() == 0) return;
flushing = true;
asio::async_write(socket, send_buffer, [&](auto, auto) {
// error handling
// as per doc data is consumed from the buffer automatically
flushing = false;
flush(); // not sure if this even needs to be called
});
}
While the lifetime of the streambuf itself is clear, I am concerned that adding new data will invalidate any buffers that view into its memory. That would be find if this is isolated to within handlers, but I cannot find any documentation as to whether that is true or not.
It appears that
socket.async_write_some(send_buffer, (auto, auto){});
does not work at all, it would require send_buffer.data() - which would be invalidated by operations on send_buffer as is documented.
I have also considered asio::buffered_write_stream, but it seems that it does not provide a simple way to dump data in a guaranteed non-blocking way.
The underlying sockets are tcp and ssl sockets. All handlers are executed in the same strand.
c++ boost io boost-asio
c++ boost io boost-asio
asked Nov 23 '18 at 13:29
ZulanZulan
16k63373
asked Nov 23 '18 at 13:29
ZulanZulan
16k63373
asked Nov 23 '18 at 13:29
ZulanZulan
16k63373
asked Nov 23 '18 at 13:29
ZulanZulan
16k63373
asked Nov 23 '18 at 13:29
ZulanZulan
16k63373
16k63373
See stackoverflow.com/a/12801042/85371
– sehe
Nov 24 '18 at 15:46
add a comment |
See stackoverflow.com/a/12801042/85371
– sehe
Nov 24 '18 at 15:46
See stackoverflow.com/a/12801042/85371
– sehe
Nov 24 '18 at 15:46
See stackoverflow.com/a/12801042/85371
– sehe
Nov 24 '18 at 15:46
add a comment |
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See stackoverflow.com/a/12801042/85371
– sehe
Nov 24 '18 at 15:46