Write a program which processed data output from ssh request, data from request returns in real time ~1024 bytes per second and i want to process it in real time (drawing a graphics). But ssh_channel_poll function return non zero only when 4096 bytes or when end of output. Channel and session setting up like non-blocking.
bool SSHConnection::execute_process(const std::string &command) {
try {
if (!connect())
throw std::string("Connection error");
if (this->is_processed)
throw std::string("Process already going");
this->process_channel = ssh_channel_new(this->connection);
if (this->process_channel == nullptr)
throw std::string("Channel create error");
int rc = ssh_channel_open_session(this->process_channel);
if (rc != SSH_OK) {
ssh_channel_free(this->process_channel);
throw std::string("Channel open error");
}
rc = ssh_channel_request_exec(this->process_channel, command.c_str());
if (rc != SSH_OK) {
ssh_channel_free(this->process_channel);
throw std::string("Execute command error");
}
ssh_set_blocking(this->connection, 0);
ssh_channel_set_blocking(this->process_channel, 0);
this->is_processed = true;
this->process_thread = new std::thread(&SSHConnection::process, this);
} catch (const std::string &err_msg) {
std::cerr << err_msg << std::endl;
emit Error(QString::fromStdString(err_msg));
return false;
}
return true;
}
void SSHConnection::process() {
std::string output;
char buffer[256];
int nbytes;
while (!ssh_channel_is_eof(this->process_channel) && this->is_processed) {
if (ssh_channel_poll(this->process_channel, 0) > 0) {
nbytes =
ssh_channel_read_nonblocking(this->process_channel, buffer, sizeof(buffer), 0);
output.clear();
output.append(buffer, nbytes);
emit DataReady(QString::fromStdString(output));
}
}
this->is_processed = false;
ssh_channel_send_eof(this->process_channel);
ssh_channel_close(this->process_channel);
ssh_channel_free(this->process_channel);
disconnect();
emit DataEnd();
}
How to change polling trigger from 4096 to lower?
