//
// Copyright 2017 Ettus Research, a National Instruments Company
// Copyright 2019 Ettus Research, A National Instruments Brand
//
// SPDX-License-Identifier: GPL-3.0-or-later
//
#pragma once
#include <uhd/exception.hpp>
#include <uhd/utils/log.hpp>
#include <rpc/client.h>
#include <rpc/rpc_error.h>
#include <boost/format.hpp>
#include <chrono>
#include <memory>
#include <mutex>
#include <string>
#include <thread>
namespace {
constexpr uint64_t DEFAULT_RPC_TIMEOUT_MS = 2000;
bool await_rpc_connected_state(
std::shared_ptr<rpc::client> client, std::chrono::milliseconds timeout)
{
const auto timeout_time = std::chrono::steady_clock::now() + timeout;
rpc::client::connection_state state = client->get_connection_state();
while (state == rpc::client::connection_state::initial
and std::chrono::steady_clock::now() < timeout_time) {
std::this_thread::sleep_for(std::chrono::milliseconds(1));
state = client->get_connection_state();
}
// guarantee at least one check at the end of timeout
if (state == rpc::client::connection_state::initial) {
state = client->get_connection_state();
}
return state == rpc::client::connection_state::connected;
}
} // namespace
namespace uhd {
/*! Abstraction for RPC client
*
* Purpose of this class is to wrap the underlying RPC implementation.
* This class holds a connection to an RPC server (the connection is severed on
* destruction).
*/
class rpc_client
{
public:
using sptr = std::shared_ptr<rpc_client>;
static sptr make(const std::string& addr,
const uint16_t port,
const uint64_t timeout_ms = DEFAULT_RPC_TIMEOUT_MS,
const std::string& get_last_error_cmd = "")
{
return std::make_shared<rpc_client>(addr, port, timeout_ms, get_last_error_cmd);
}
/*!
* \param addr An IP address to connect to
* \param port Port to connect to
* \param get_last_error_cmd A command that queries an error string from
* the RPC server. If set, the RPC client will
* try and use this command to fetch information
* about what went wrong on the client side.
*/
rpc_client(const std::string& addr,
const uint16_t port,
const uint64_t timeout_ms = DEFAULT_RPC_TIMEOUT_MS,
std::string const& get_last_error_cmd = "")
: _get_last_error_cmd(get_last_error_cmd), _default_timeout_ms(timeout_ms)
{
_client = std::make_shared<rpc::client>(addr, port);
// wait for asynchronous creation to finish
if (!await_rpc_connected_state(
_client, std::chrono::milliseconds(DEFAULT_RPC_TIMEOUT_MS))) {
throw uhd::runtime_error(str(
boost::format(
"Unknown error during attempt to establish RPC connection at %s:%d")
% addr % port));
}
_client->set_timeout(_default_timeout_ms);
}
/*! Perform an RPC request.
*
* Thread safe (locked). This function blocks until it receives a valid
* response from the server.
*
* \param func_name The function name that is called via RPC
* \param args All these arguments are passed to the RPC call
*
* \throws uhd::runtime_error in case of failure
*/
template <typename return_type, typename... Args>
return_type request(std::string const& func_name, Args&&... args)
{
std::lock_guard<std::mutex> lock(_mutex);
try {
return _client->call(func_name, std::forward<Args>(args)...)
.template as<return_type>();
} catch (const ::rpc::rpc_error& ex) {
const std::string error = _get_last_error_safe();
if (not error.empty()) {
UHD_LOG_ERROR("RPC", error);
}
throw uhd::runtime_error(
str(boost::format("Error during RPC call to `%s'. Error message: %s")
% func_name % (error.empty() ? ex.what() : error)));
} catch (const std::bad_cast& ex) {
throw uhd::runtime_error(
str(boost::format("Error during RPC call to `%s'. Error message: %s")
% func_name % ex.what()));
}
};
/*! Perform an RPC request.
*
* Thread safe (locked). This function blocks until it receives a valid
* response from the server.
*
* \param timeout_ms is time limit for this RPC call.
* \param func_name The function name that is called via RPC
* \param args All these arguments are passed to the RPC call
*
* \throws uhd::runtime_error in case of failure
*/
template <typename return_type, typename... Args>
return_type request(uint64_t timeout_ms, std::string const& func_name, Args&&... args)
{
std::lock_guard<std::mutex> lock(_mutex);
auto holder = rpcc_timeout_holder(_client, timeout_ms, _default_timeout_ms);
try {
return _client->call(func_name, std::forward<Args>(args)...)
.template as<return_type>();
} catch (const ::rpc::rpc_error& ex) {
const std::string error = _get_last_error_safe();
if (not error.empty()) {
UHD_LOG_ERROR("RPC", error);
}
throw uhd::runtime_error(
str(boost::format("Error during RPC call to `%s'. Error message: %s")
% func_name % (error.empty() ? ex.what() : error)));
} catch (const std::bad_cast& ex) {
throw uhd::runtime_error(
str(boost::format("Error during RPC call to `%s'. Error message: %s")
% func_name % ex.what()));
}
};
/*! Perform an RPC notification.
*
* Thread safe (locked). This function does not require a response from the
* server, although the underlying implementation may provide one.
*
* \param timeout_ms is time limit for this RPC call.
* \param func_name The function name that is called via RPC
* \param args All these arguments are passed to the RPC call
*
* \throws uhd::runtime_error in case of failure
*/
template <typename... Args>
void notify(uint64_t timeout_ms, std::string const& func_name, Args&&... args)
{
std::lock_guard<std::mutex> lock(_mutex);
auto holder = rpcc_timeout_holder(_client, timeout_ms, _default_timeout_ms);
try {
_client->call(func_name, std::forward<Args>(args)...);
} catch (const ::rpc::rpc_error& ex) {
const std::string error = _get_last_error_safe();
if (not error.empty()) {
UHD_LOG_ERROR("RPC", error);
}
throw uhd::runtime_error(
str(boost::format("Error during RPC call to `%s'. Error message: %s")
% func_name % (error.empty() ? ex.what() : error)));
} catch (const std::bad_cast& ex) {
throw uhd::runtime_error(
str(boost::format("Error during RPC call to `%s'. Error message: %s")
% func_name % ex.what()));
}
};
/*! Perform an RPC notification.
*
* Thread safe (locked). This function does not require a response from the
* server, although the underlying implementation may provide one.
*
* \param func_name The function name that is called via RPC
* \param args All these arguments are passed to the RPC call
*
* \throws uhd::runtime_error in case of failure
*/
template <typename... Args>
void notify(std::string const& func_name, Args&&... args)
{
std::lock_guard<std::mutex> lock(_mutex);
try {
_client->call(func_name, std::forward<Args>(args)...);
} catch (const ::rpc::rpc_error& ex) {
const std::string error = _get_last_error_safe();
if (not error.empty()) {
UHD_LOG_ERROR("RPC", error);
}
throw uhd::runtime_error(
str(boost::format("Error during RPC call to `%s'. Error message: %s")
% func_name % (error.empty() ? ex.what() : error)));
} catch (const std::bad_cast& ex) {
throw uhd::runtime_error(
str(boost::format("Error during RPC call to `%s'. Error message: %s")
% func_name % ex.what()));
}
};
/*! Like request(), also provides a token.
*
* This is a convenience wrapper to directly call a function that requires
* a token without having to have a copy of the token.
*/
template <typename return_type, typename... Args>
return_type request_with_token(std::string const& func_name, Args&&... args)
{
return request<return_type>(func_name, _token, std::forward<Args>(args)...);
};
/*! Like request_with_token(), but it can be specified different timeout than default.
*/
template <typename return_type, typename... Args>
return_type request_with_token(
uint64_t timeout_ms, std::string const& func_name, Args&&... args)
{
return request<return_type>(
timeout_ms, func_name, _token, std::forward<Args>(args)...);
};
/*! Like notify(), also provides a token.
*
* This is a convenience wrapper to directly call a function that requires
* a token without having to have a copy of the token.
*/
template <typename... Args>
void notify_with_token(std::string const& func_name, Args&&... args)
{
notify(func_name, _token, std::forward<Args>(args)...);
};
/*! Like notify_with_token() but it can be specified different timeout than default.
*/
template <typename... Args>
void notify_with_token(
uint64_t timeout_ms, std::string const& func_name, Args&&... args)
{
notify(timeout_ms, func_name, _token, std::forward<Args>(args)...);
};
/*! Sets the token value. This is used by the `_with_token` methods.
*/
void set_token(const std::string& token)
{
_token = token;
}
private:
/*! This is internal object to hold timeout of the rpc client
* it is used as an RAII in code block.
*/
class rpcc_timeout_holder
{
public:
rpcc_timeout_holder(std::shared_ptr<rpc::client> client,
uint64_t set_timeout,
uint64_t resume_timeout)
: _rpcc(client), _save_timeout(resume_timeout)
{
_rpcc->set_timeout(set_timeout);
}
~rpcc_timeout_holder()
{
_rpcc->set_timeout(_save_timeout);
}
private:
std::shared_ptr<rpc::client> _rpcc;
uint64_t _save_timeout;
};
/*! Pull the last error out of the RPC server. Not thread-safe, meant to
* be called from notify() or request().
*
* This function will do its best not to get in anyone's way. If it can't
* get an error string, it'll return an empty string.
*/
std::string _get_last_error_safe()
{
if (_get_last_error_cmd.empty()) {
return "";
}
try {
return _client->call(_get_last_error_cmd).as<std::string>();
} catch (const ::rpc::rpc_error&) {
// nop
} catch (const std::bad_cast&) {
// nop
} catch (...) {
// nop
}
return "";
}
//! Reference the actual RPC client
std::shared_ptr<rpc::client> _client;
//! If set, this is the command that will retrieve an error
const std::string _get_last_error_cmd;
uint64_t _default_timeout_ms;
std::string _token;
std::mutex _mutex;
};
} /* namespace uhd */