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sdbus-cpp/include/sdbus-c++/IProxy.h
Stanislav Angelovic b65461c404 refactor: add nodiscard attribute for some functions
2024-04-24 20:20:29 +02:00

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/**
* (C) 2016 - 2021 KISTLER INSTRUMENTE AG, Winterthur, Switzerland
* (C) 2016 - 2024 Stanislav Angelovic <stanislav.angelovic@protonmail.com>
*
* @file IProxy.h
*
* Created on: Nov 8, 2016
* Project: sdbus-c++
* Description: High-level D-Bus IPC C++ library based on sd-bus
*
* This file is part of sdbus-c++.
*
* sdbus-c++ is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 2.1 of the License, or
* (at your option) any later version.
*
* sdbus-c++ is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with sdbus-c++. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef SDBUS_CXX_IPROXY_H_
#define SDBUS_CXX_IPROXY_H_
#include <sdbus-c++/ConvenienceApiClasses.h>
#include <sdbus-c++/TypeTraits.h>
#include <string>
#include <memory>
#include <functional>
#include <chrono>
#include <future>
// Forward declarations
namespace sdbus {
class MethodCall;
class MethodReply;
class IConnection;
class PendingAsyncCall;
namespace internal {
class Proxy;
}
}
namespace sdbus {
/********************************************//**
* @class IProxy
*
* IProxy class represents a proxy object, which is a convenient local object created
* to represent a remote D-Bus object in another process.
* The proxy enables calling methods on remote objects, receiving signals from remote
* objects, and getting/setting properties of remote objects.
*
* All IProxy member methods throw @c sdbus::Error in case of D-Bus or sdbus-c++ error.
* The IProxy class has been designed as thread-aware. However, the operation of
* creating and sending method calls (both synchronously and asynchronously) is
* thread-safe by design.
*
***********************************************/
class IProxy
{
public:
virtual ~IProxy() = default;
/*!
* @brief Creates a method call message
*
* @param[in] interfaceName Name of an interface that provides a given method
* @param[in] methodName Name of the method
* @return A method call message
*
* Serialize method arguments into the returned message and invoke the method by passing
* the message with serialized arguments to the @c callMethod function.
* Alternatively, use higher-level API @c callMethod(const std::string& methodName) defined below.
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] virtual MethodCall createMethodCall(const std::string& interfaceName, const std::string& methodName) = 0;
/*!
* @brief Calls method on the remote D-Bus object
*
* @param[in] message Message representing a method call
* @param[in] timeout Timeout for dbus call in microseconds
* @return A method reply message
*
* The call does not block if the method call has dont-expect-reply flag set. In that case,
* the call returns immediately and the return value is an empty, invalid method reply.
*
* The call blocks otherwise, waiting for the remote peer to send back a reply or an error,
* or until the call times out.
*
* While blocking, other concurrent operations (in other threads) on the underlying bus
* connection are stalled until the call returns. This is not an issue in vast majority of
* (simple, single-threaded) applications. In asynchronous, multi-threaded designs involving
* shared bus connections, this may be an issue. It is advised to instead use an asynchronous
* callMethod() function overload, which does not block the bus connection, or do the synchronous
* call from another Proxy instance created just before the call and then destroyed (which is
* anyway quite a typical approach in D-Bus implementations). Such proxy instance must have
* its own bus connection. So-called light-weight proxies (ones created with `dont_run_event_loop_thread`
* tag are designed for exactly that purpose.
*
* Note: To avoid messing with messages, use API on a higher level of abstraction defined below.
*
* @throws sdbus::Error in case of failure (also in case the remote function returned an error)
*/
virtual MethodReply callMethod(const MethodCall& message, uint64_t timeout = 0) = 0;
/*!
* @copydoc IProxy::callMethod(const MethodCall&,uint64_t)
*/
template <typename _Rep, typename _Period>
MethodReply callMethod(const MethodCall& message, const std::chrono::duration<_Rep, _Period>& timeout);
/*!
* @brief Calls method on the D-Bus object asynchronously
*
* @param[in] message Message representing an async method call
* @param[in] asyncReplyCallback Handler for the async reply
* @param[in] timeout Timeout for dbus call in microseconds
* @return Cookie for the the pending asynchronous call
*
* This is a callback-based way of asynchronously calling a remote D-Bus method.
*
* The call itself is non-blocking. It doesn't wait for the reply. Once the reply arrives,
* the provided async reply handler will get invoked from the context of the bus
* connection I/O event loop thread.
*
* Note: To avoid messing with messages, use API on a higher level of abstraction defined below.
*
* @throws sdbus::Error in case of failure
*/
virtual PendingAsyncCall callMethod(const MethodCall& message, async_reply_handler asyncReplyCallback, uint64_t timeout = 0) = 0;
/*!
* @copydoc IProxy::callMethod(const MethodCall&,async_reply_handler,uint64_t)
*/
template <typename _Rep, typename _Period>
PendingAsyncCall callMethod(const MethodCall& message, async_reply_handler asyncReplyCallback, const std::chrono::duration<_Rep, _Period>& timeout);
/*!
* @brief Calls method on the D-Bus object asynchronously
*
* @param[in] message Message representing an async method call
* @param[in] Tag denoting a std::future-based overload
* @return Future object providing access to the future method reply message
*
* This is a std::future-based way of asynchronously calling a remote D-Bus method.
*
* The call itself is non-blocking. It doesn't wait for the reply. Once the reply arrives,
* the provided future object will be set to contain the reply (or sdbus::Error
* in case the remote method threw an exception).
*
* Note: To avoid messing with messages, use higher-level API defined below.
*
* @throws sdbus::Error in case of failure
*/
virtual std::future<MethodReply> callMethod(const MethodCall& message, with_future_t) = 0;
/*!
* @brief Calls method on the D-Bus object asynchronously, with custom timeout
*
* @param[in] message Message representing an async method call
* @param[in] timeout Method call timeout
* @param[in] Tag denoting a std::future-based overload
* @return Future object providing access to the future method reply message
*
* This is a std::future-based way of asynchronously calling a remote D-Bus method.
*
* The call itself is non-blocking. It doesn't wait for the reply. Once the reply arrives,
* the provided future object will be set to contain the reply (or sdbus::Error
* in case the remote method threw an exception, or the call timed out).
*
* Note: To avoid messing with messages, use higher-level API defined below.
*
* @throws sdbus::Error in case of failure
*/
virtual std::future<MethodReply> callMethod(const MethodCall& message, uint64_t timeout, with_future_t) = 0;
/*!
* @copydoc IProxy::callMethod(const MethodCall&,uint64_t,with_future_t)
*/
template <typename _Rep, typename _Period>
std::future<MethodReply> callMethod( const MethodCall& message
, const std::chrono::duration<_Rep, _Period>& timeout
, with_future_t );
/*!
* @brief Registers a handler for the desired signal emitted by the D-Bus object
*
* @param[in] interfaceName Name of an interface that the signal belongs to
* @param[in] signalName Name of the signal
* @param[in] signalHandler Callback that implements the body of the signal handler
*
* A signal can be subscribed to and unsubscribed from at any time during proxy
* lifetime. The subscription is active immediately after the call.
*
* @throws sdbus::Error in case of failure
*/
virtual void registerSignalHandler( const std::string& interfaceName
, const std::string& signalName
, signal_handler signalHandler ) = 0;
/*!
* @brief Registers a handler for the desired signal emitted by the D-Bus object
*
* @param[in] interfaceName Name of an interface that the signal belongs to
* @param[in] signalName Name of the signal
* @param[in] signalHandler Callback that implements the body of the signal handler
*
* @return RAII-style slot handle representing the ownership of the subscription
*
* A signal can be subscribed to and unsubscribed from at any time during proxy
* lifetime. The subscription is active immediately after the call. The subscription
* is unregistered when the client destroys the returned slot object.
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] virtual Slot registerSignalHandler( const std::string& interfaceName
, const std::string& signalName
, signal_handler signalHandler
, return_slot_t ) = 0;
/*!
* @brief Unregisters proxy's signal handlers and stops receiving replies to pending async calls
*
* Unregistration is done automatically also in proxy's destructor. This method makes
* sense if, in the process of proxy removal, we need to make sure that callbacks
* are unregistered explicitly before the final destruction of the proxy instance.
*
* @throws sdbus::Error in case of failure
*/
virtual void unregister() = 0;
/*!
* @brief Calls method on the D-Bus object
*
* @param[in] methodName Name of the method
* @return A helper object for convenient invocation of the method
*
* This is a high-level, convenience way of calling D-Bus methods that abstracts
* from the D-Bus message concept. Method arguments/return value are automatically (de)serialized
* in a message and D-Bus signatures automatically deduced from the provided native arguments
* and return values.
*
* Example of use:
* @code
* int result, a = ..., b = ...;
* object_.callMethod("multiply").onInterface(INTERFACE_NAME).withArguments(a, b).storeResultsTo(result);
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] MethodInvoker callMethod(const std::string& methodName);
/*!
* @brief Calls method on the D-Bus object asynchronously
*
* @param[in] methodName Name of the method
* @return A helper object for convenient asynchronous invocation of the method
*
* This is a high-level, convenience way of calling D-Bus methods that abstracts
* from the D-Bus message concept. Method arguments/return value are automatically (de)serialized
* in a message and D-Bus signatures automatically deduced from the provided native arguments
* and return values.
*
* Example of use:
* @code
* int a = ..., b = ...;
* object_.callMethodAsync("multiply").onInterface(INTERFACE_NAME).withArguments(a, b).uponReplyInvoke([](int result)
* {
* std::cout << "Got result of multiplying " << a << " and " << b << ": " << result << std::endl;
* });
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] AsyncMethodInvoker callMethodAsync(const std::string& methodName);
/*!
* @brief Registers signal handler for a given signal of the D-Bus object
*
* @param[in] signalName Name of the signal
* @return A helper object for convenient registration of the signal handler
*
* This is a high-level, convenience way of registering to D-Bus signals that abstracts
* from the D-Bus message concept. Signal arguments are automatically serialized
* in a message and D-Bus signatures automatically deduced from the parameters
* of the provided native signal callback.
*
* A signal can be subscribed to and unsubscribed from at any time during proxy
* lifetime. The subscription is active immediately after the call.
*
* Example of use:
* @code
* object_.uponSignal("fooSignal").onInterface("com.kistler.foo").call([this](int arg1, double arg2){ this->onFooSignal(arg1, arg2); });
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] SignalSubscriber uponSignal(const std::string& signalName);
/*!
* @brief Gets value of a property of the D-Bus object
*
* @param[in] propertyName Name of the property
* @return A helper object for convenient getting of property value
*
* This is a high-level, convenience way of reading D-Bus property values that abstracts
* from the D-Bus message concept. sdbus::Variant is returned which shall then be converted
* to the real property type (implicit conversion is supported).
*
* Example of use:
* @code
* int state = object.getProperty("state").onInterface("com.kistler.foo");
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] PropertyGetter getProperty(const std::string& propertyName);
/*!
* @brief Gets value of a property of the D-Bus object asynchronously
*
* @param[in] propertyName Name of the property
* @return A helper object for convenient asynchronous getting of property value
*
* This is a high-level, convenience way of reading D-Bus property values that abstracts
* from the D-Bus message concept.
*
* Example of use:
* @code
* std::future<sdbus::Variant> state = object.getPropertyAsync("state").onInterface("com.kistler.foo").getResultAsFuture();
* auto callback = [](const sdbus::Error* err, const sdbus::Variant& value){ ... };
* object.getPropertyAsync("state").onInterface("com.kistler.foo").uponReplyInvoke(std::move(callback));
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] AsyncPropertyGetter getPropertyAsync(const std::string& propertyName);
/*!
* @brief Sets value of a property of the D-Bus object
*
* @param[in] propertyName Name of the property
* @return A helper object for convenient setting of property value
*
* This is a high-level, convenience way of writing D-Bus property values that abstracts
* from the D-Bus message concept.
* Setting property value with NoReply flag is also supported.
*
* Example of use:
* @code
* int state = ...;
* object_.setProperty("state").onInterface("com.kistler.foo").toValue(state);
* // Or we can just send the set message call without waiting for the reply
* object_.setProperty("state").onInterface("com.kistler.foo").toValue(state, dont_expect_reply);
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] PropertySetter setProperty(const std::string& propertyName);
/*!
* @brief Sets value of a property of the D-Bus object asynchronously
*
* @param[in] propertyName Name of the property
* @return A helper object for convenient asynchronous setting of property value
*
* This is a high-level, convenience way of writing D-Bus property values that abstracts
* from the D-Bus message concept.
*
* Example of use:
* @code
* int state = ...;
* // We can wait until the set operation finishes by waiting on the future
* std::future<void> res = object_.setPropertyAsync("state").onInterface("com.kistler.foo").toValue(state).getResultAsFuture();
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] AsyncPropertySetter setPropertyAsync(const std::string& propertyName);
/*!
* @brief Gets values of all properties of the D-Bus object
*
* @return A helper object for convenient getting of properties' values
*
* This is a high-level, convenience way of reading D-Bus properties' values that abstracts
* from the D-Bus message concept.
*
* Example of use:
* @code
* auto props = object.getAllProperties().onInterface("com.kistler.foo");
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] AllPropertiesGetter getAllProperties();
/*!
* @brief Gets values of all properties of the D-Bus object asynchronously
*
* @return A helper object for convenient asynchronous getting of properties' values
*
* This is a high-level, convenience way of reading D-Bus properties' values that abstracts
* from the D-Bus message concept.
*
* Example of use:
* @code
* auto callback = [](const sdbus::Error* err, const std::map<std::string, Variant>>& properties){ ... };
* auto props = object.getAllPropertiesAsync().onInterface("com.kistler.foo").uponReplyInvoke(std::move(callback));
* @endcode
*
* @throws sdbus::Error in case of failure
*/
[[nodiscard]] AsyncAllPropertiesGetter getAllPropertiesAsync();
/*!
* @brief Provides D-Bus connection used by the proxy
*
* @return Reference to the D-Bus connection
*/
[[nodiscard]] virtual sdbus::IConnection& getConnection() const = 0;
/*!
* @brief Returns object path of the underlying DBus object
*/
[[nodiscard]] virtual const std::string& getObjectPath() const = 0;
/*!
* @brief Provides access to the currently processed D-Bus message
*
* This method provides access to the currently processed incoming D-Bus message.
* "Currently processed" means that the registered callback handler(s) for that message
* are being invoked. This method is meant to be called from within a callback handler
* (e.g. from a D-Bus signal handler, or async method reply handler, etc.). In such a case it is
* guaranteed to return a valid D-Bus message instance for which the handler is called.
* If called from other contexts/threads, it may return a valid or invalid message, depending
* on whether a message was processed or not at the time of the call.
*
* @return Currently processed D-Bus message
*/
[[nodiscard]] virtual Message getCurrentlyProcessedMessage() const = 0;
};
/********************************************//**
* @class PendingAsyncCall
*
* PendingAsyncCall represents a simple handle type to cancel the delivery
* of the asynchronous D-Bus call result to the application.
*
* The handle is lifetime-independent from the originating Proxy object.
* It's safe to call its methods even after the Proxy has gone.
*
***********************************************/
class PendingAsyncCall
{
public:
PendingAsyncCall() = default;
/*!
* @brief Cancels the delivery of the pending asynchronous call result
*
* This function effectively removes the callback handler registered to the
* async D-Bus method call result delivery. Does nothing if the call was
* completed already, or if the originating Proxy object has gone meanwhile.
*/
void cancel();
/*!
* @brief Answers whether the asynchronous call is still pending
*
* @return True if the call is pending, false if the call has been fully completed
*
* Pending call in this context means a call whose results have not arrived, or
* have arrived and are currently being processed by the callback handler.
*/
bool isPending() const;
private:
friend internal::Proxy;
PendingAsyncCall(std::weak_ptr<void> callData);
private:
std::weak_ptr<void> callData_;
};
// Out-of-line member definitions
template <typename _Rep, typename _Period>
inline MethodReply IProxy::callMethod(const MethodCall& message, const std::chrono::duration<_Rep, _Period>& timeout)
{
auto microsecs = std::chrono::duration_cast<std::chrono::microseconds>(timeout);
return callMethod(message, microsecs.count());
}
template <typename _Rep, typename _Period>
inline PendingAsyncCall IProxy::callMethod(const MethodCall& message, async_reply_handler asyncReplyCallback, const std::chrono::duration<_Rep, _Period>& timeout)
{
auto microsecs = std::chrono::duration_cast<std::chrono::microseconds>(timeout);
return callMethod(message, std::move(asyncReplyCallback), microsecs.count());
}
template <typename _Rep, typename _Period>
inline std::future<MethodReply> IProxy::callMethod( const MethodCall& message
, const std::chrono::duration<_Rep, _Period>& timeout
, with_future_t )
{
auto microsecs = std::chrono::duration_cast<std::chrono::microseconds>(timeout);
return callMethod(message, microsecs.count(), with_future);
}
inline MethodInvoker IProxy::callMethod(const std::string& methodName)
{
return MethodInvoker(*this, methodName);
}
inline AsyncMethodInvoker IProxy::callMethodAsync(const std::string& methodName)
{
return AsyncMethodInvoker(*this, methodName);
}
inline SignalSubscriber IProxy::uponSignal(const std::string& signalName)
{
return SignalSubscriber(*this, signalName);
}
inline PropertyGetter IProxy::getProperty(const std::string& propertyName)
{
return PropertyGetter(*this, propertyName);
}
inline AsyncPropertyGetter IProxy::getPropertyAsync(const std::string& propertyName)
{
return AsyncPropertyGetter(*this, propertyName);
}
inline PropertySetter IProxy::setProperty(const std::string& propertyName)
{
return PropertySetter(*this, propertyName);
}
inline AsyncPropertySetter IProxy::setPropertyAsync(const std::string& propertyName)
{
return AsyncPropertySetter(*this, propertyName);
}
inline AllPropertiesGetter IProxy::getAllProperties()
{
return AllPropertiesGetter(*this);
}
inline AsyncAllPropertiesGetter IProxy::getAllPropertiesAsync()
{
return AsyncAllPropertiesGetter(*this);
}
/*!
* @brief Creates a proxy object for a specific remote D-Bus object
*
* @param[in] connection D-Bus connection to be used by the proxy object
* @param[in] destination Bus name that provides the remote D-Bus object
* @param[in] objectPath Path of the remote D-Bus object
* @return Pointer to the proxy object instance
*
* The provided connection will be used by the proxy to issue calls against the object,
* and signals, if any, will be subscribed to on this connection. The caller still
* remains the owner of the connection (the proxy just keeps a reference to it), and
* should make sure that an I/O event loop is running on that connection, so the proxy
* may receive incoming signals and asynchronous method replies.
*
* The destination parameter may be an empty string (useful e.g. in case of direct
* D-Bus connections to a custom server bus).
*
* Code example:
* @code
* auto proxy = sdbus::createProxy(connection, "com.kistler.foo", "/com/kistler/foo");
* @endcode
*/
[[nodiscard]] std::unique_ptr<sdbus::IProxy> createProxy( sdbus::IConnection& connection
, std::string destination
, std::string objectPath );
/*!
* @brief Creates a proxy object for a specific remote D-Bus object
*
* @param[in] connection D-Bus connection to be used by the proxy object
* @param[in] destination Bus name that provides the remote D-Bus object
* @param[in] objectPath Path of the remote D-Bus object
* @return Pointer to the object proxy instance
*
* The provided connection will be used by the proxy to issue calls against the object,
* and signals, if any, will be subscribed to on this connection. The Object proxy becomes
* an exclusive owner of this connection, and will automatically start a procesing loop
* upon that connection in a separate internal thread. Handlers for incoming signals and
* asynchronous method replies will be executed in the context of that thread.
*
* The destination parameter may be an empty string (useful e.g. in case of direct
* D-Bus connections to a custom server bus).
*
* Code example:
* @code
* auto proxy = sdbus::createProxy(std::move(connection), "com.kistler.foo", "/com/kistler/foo");
* @endcode
*/
[[nodiscard]] std::unique_ptr<sdbus::IProxy> createProxy( std::unique_ptr<sdbus::IConnection>&& connection
, std::string destination
, std::string objectPath );
/*!
* @brief Creates a proxy object for a specific remote D-Bus object
*
* @param[in] connection D-Bus connection to be used by the proxy object
* @param[in] destination Bus name that provides the remote D-Bus object
* @param[in] objectPath Path of the remote D-Bus object
* @return Pointer to the object proxy instance
*
* The provided connection will be used by the proxy to issue calls against the object.
* The Object proxy becomes an exclusive owner of this connection, but will not start
* an event loop thread on this connection. This is cheap construction and is suitable
* for short-lived proxies created just to execute simple synchronous D-Bus calls and
* then destroyed. Such blocking request-reply calls will work without an event loop
* (but signals, async calls, etc. won't).
*
* The destination parameter may be an empty string (useful e.g. in case of direct
* D-Bus connections to a custom server bus).
*
* Code example:
* @code
* auto proxy = sdbus::createProxy(std::move(connection), "com.kistler.foo", "/com/kistler/foo", sdbus::dont_run_event_loop_thread);
* @endcode
*/
[[nodiscard]] std::unique_ptr<sdbus::IProxy> createProxy( std::unique_ptr<sdbus::IConnection>&& connection
, std::string destination
, std::string objectPath
, dont_run_event_loop_thread_t );
/*!
* @brief Creates a proxy object for a specific remote D-Bus object
*
* @param[in] destination Bus name that provides the remote D-Bus object
* @param[in] objectPath Path of the remote D-Bus object
* @return Pointer to the object proxy instance
*
* No D-Bus connection is provided here, so the object proxy will create and manage
* his own connection, and will automatically start an event loop upon that connection
* in a separate internal thread. Handlers for incoming signals and asynchronous
* method replies will be executed in the context of that thread.
*
* Code example:
* @code
* auto proxy = sdbus::createProxy("com.kistler.foo", "/com/kistler/foo");
* @endcode
*/
[[nodiscard]] std::unique_ptr<sdbus::IProxy> createProxy( std::string destination
, std::string objectPath );
/*!
* @brief Creates a proxy object for a specific remote D-Bus object
*
* @param[in] destination Bus name that provides the remote D-Bus object
* @param[in] objectPath Path of the remote D-Bus object
* @return Pointer to the object proxy instance
*
* No D-Bus connection is provided here, so the object proxy will create and manage
* his own connection, but it will not start an event loop thread. This is cheap
* construction and is suitable for short-lived proxies created just to execute simple
* synchronous D-Bus calls and then destroyed. Such blocking request-reply calls
* will work without an event loop (but signals, async calls, etc. won't).
*
* Code example:
* @code
* auto proxy = sdbus::createProxy("com.kistler.foo", "/com/kistler/foo", sdbus::dont_run_event_loop_thread );
* @endcode
*/
[[nodiscard]] std::unique_ptr<sdbus::IProxy> createProxy( std::string destination
, std::string objectPath
, dont_run_event_loop_thread_t );
}
#include <sdbus-c++/ConvenienceApiClasses.inl>
#endif /* SDBUS_CXX_IPROXY_H_ */
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