void NetworkInterfaceASIO::_asyncRunCommand(AsyncOp* op, NetworkOpHandler handler) {
LOG(2) << "Starting asynchronous command " << op->request().id << " on host "
<< op->request().target.toString();
if (MONGO_FAIL_POINT(NetworkInterfaceASIOasyncRunCommandFail)) {
_validateAndRun(op, asio::error::basic_errors::network_unreachable, [] {});
return;
}
// We invert the following steps below to run a command:
// 1 - send the given command
// 2 - receive a header for the response
// 3 - validate and receive response body
// 4 - advance the state machine by calling handler()
auto cmd = op->command();
// Step 4
auto recvMessageCallback = [this, cmd, handler, op](std::error_code ec, size_t bytes) {
// We don't call _validateAndRun here as we assume the caller will.
handler(ec, bytes);
};
// Step 3
auto recvHeaderCallback = [this, cmd, handler, recvMessageCallback, op](std::error_code ec,
size_t bytes) {
// The operation could have been canceled after starting the command, but before
// receiving the header
_validateAndRun(op, ec, [this, op, recvMessageCallback, ec, bytes, cmd, handler] {
// validate response id
uint32_t expectedId = cmd->toSend().header().getId();
uint32_t actualId = cmd->header().constView().getResponseToMsgId();
if (actualId != expectedId) {
LOG(3) << "got wrong response:"
<< " expected response id: " << expectedId
<< ", got response id: " << actualId;
return handler(make_error_code(ErrorCodes::ProtocolError), bytes);
}
asyncRecvMessageBody(cmd->conn().stream(),
&cmd->header(),
&cmd->toRecv(),
std::move(recvMessageCallback));
});
};
// Step 2
auto sendMessageCallback = [this, cmd, handler, recvHeaderCallback, op](std::error_code ec,
size_t bytes) {
_validateAndRun(op, ec, [this, cmd, op, recvHeaderCallback] {
asyncRecvMessageHeader(
cmd->conn().stream(), &cmd->header(), std::move(recvHeaderCallback));
});
};
// Step 1
asyncSendMessage(cmd->conn().stream(), &cmd->toSend(), std::move(sendMessageCallback));
}
void NetworkInterfaceASIO::_asyncRunCommand(AsyncCommand* cmd, NetworkOpHandler handler) {
// We invert the following steps below to run a command:
// 1 - send the given command
// 2 - receive a header for the response
// 3 - validate and receive response body
// 4 - advance the state machine by calling handler()
// Step 4
auto recvMessageCallback =
[this, cmd, handler](std::error_code ec, size_t bytes) { handler(ec, bytes); };
// Step 3
auto recvHeaderCallback = [this, cmd, handler, recvMessageCallback](std::error_code ec,
size_t bytes) {
if (ec)
return handler(ec, bytes);
// validate response id
uint32_t expectedId = cmd->toSend().header().getId();
uint32_t actualId = cmd->header().constView().getResponseTo();
if (actualId != expectedId) {
LOG(3) << "got wrong response:"
<< " expected response id: " << expectedId << ", got response id: " << actualId;
// TODO: This error code should be more meaningful.
return handler(ec, bytes);
}
asyncRecvMessageBody(
cmd->conn().stream(), &cmd->header(), &cmd->toRecv(), std::move(recvMessageCallback));
};
// Step 2
auto sendMessageCallback = [this, cmd, handler, recvHeaderCallback](std::error_code ec,
size_t bytes) {
if (ec)
return handler(ec, bytes);
asyncRecvMessageHeader(cmd->conn().stream(), &cmd->header(), std::move(recvHeaderCallback));
};
// Step 1
asyncSendMessage(cmd->conn().stream(), &cmd->toSend(), std::move(sendMessageCallback));
}
