Introduce support for asynchronous server-side methods (#12)

* Add preliminary changes for async server methods

* Refactor the Message concept and break it into distinctive types

* Continue working on async server methods (high-level API mainly)

* Continue developing support for async server

* Finishing async server methods

* Finishing async server methods (fixing tests & cleaning up)

* A little code cleaning

* Add unit tests for type traits of free functions

* Support for generating async server methods in stub headers

* Update ChangeLog for v0.3.0

* Update the tutorial with how to use async server-side methods

* Update the TOC in sdbus-c++ tutorial

* Update numbering in TOC

* Remove unnecessary code

* Final cleanups

test/Makefile.am

@@ -14,7 +14,7 @@ endif
 
 # Setting per-file flags
 AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_srcdir)/src
-AM_CXXFLAGS = @libsdbus_cpp_CFLAGS@ @SYSTEMD_CFLAGS@ -W -Wall -Werror -pedantic -pipe -std=c++14
+AM_CXXFLAGS = @libsdbus_cpp_CFLAGS@ @SYSTEMD_CFLAGS@ -W -Wall -Werror -pedantic -pipe -std=c++17
 AM_LDFLAGS = @libsdbus_cpp_LIBS@ @SYSTEMD_LIBS@
 
 CLEANFILES = *~ *.lo *.la

test/integrationtests/AdaptorAndProxy_test.cpp

@@ -40,9 +40,12 @@
 #include <string>
 #include <thread>
 #include <tuple>
+#include <chrono>
 
 using ::testing::Eq;
 using ::testing::Gt;
+using ::testing::ElementsAre;
+using namespace std::chrono_literals;
 
 namespace
 {
@@ -67,7 +70,7 @@ private:
     {
         m_adaptor = std::make_unique<TestingAdaptor>(m_connection);
         m_proxy = std::make_unique<TestingProxy>(INTERFACE_NAME, OBJECT_PATH);
-        usleep(50000); // Give time for the proxy to start listening to signals
+        std::this_thread::sleep_for(50ms); // Give time for the proxy to start listening to signals
     }
 
     void TearDown() override
@@ -197,6 +200,31 @@ TEST_F(SdbusTestObject, CallsMethodWithComplexTypeSuccesfully)
     ASSERT_THAT(resComplex.count(0), Eq(1));
 }
 
+TEST_F(SdbusTestObject, DoesServerSideAsynchoronousMethodInParallel)
+{
+    // Yeah, this is kinda timing-dependent test, but times should be safe...
+    std::mutex mtx;
+    std::vector<uint32_t> results;
+    std::atomic<bool> invoke{};
+    std::atomic<int> startedCount{};
+    auto call = [&](uint32_t param)
+    {
+        TestingProxy proxy{INTERFACE_NAME, OBJECT_PATH};
+        ++startedCount;
+        while (!invoke) ;
+        auto result = proxy.doOperationAsync(param);
+        std::lock_guard<std::mutex> guard(mtx);
+        results.push_back(result);
+    };
+
+    std::thread invocations[]{std::thread{call, 1500}, std::thread{call, 1000}, std::thread{call, 500}};
+    while (startedCount != 3) ;
+    invoke = true;
+    std::for_each(std::begin(invocations), std::end(invocations), [](auto& t){ t.join(); });
+
+    ASSERT_THAT(results, ElementsAre(500, 1000, 1500));
+}
+
 TEST_F(SdbusTestObject, FailsCallingNonexistentMethod)
 {
     ASSERT_THROW(m_proxy->callNonexistentMethod(), sdbus::Error);

test/integrationtests/TestingAdaptor.h

@@ -27,6 +27,8 @@
 #define SDBUS_CPP_INTEGRATIONTESTS_TESTINGADAPTOR_H_
 
 #include "adaptor-glue.h"
+#include <thread>
+#include <chrono>
 
 class TestingAdaptor : public sdbus::Interfaces<testing_adaptor>
 {
@@ -97,6 +99,22 @@ protected:
         return res;
     }
 
+    uint32_t doOperationSync(uint32_t param)
+    {
+        std::this_thread::sleep_for(std::chrono::milliseconds(param));
+        return param;
+    }
+
+    void doOperationAsync(uint32_t param, sdbus::Result<uint32_t> result)
+    {
+        // The same as doOperationSync, just written as an asynchronous method callback
+        std::thread([param, result = std::move(result)]()
+        {
+            std::this_thread::sleep_for(std::chrono::milliseconds(param));
+            result.returnResults(param);
+        }).detach();
+    }
+
     sdbus::Signature getSignature() const { return SIGNATURE_VALUE; }
     sdbus::ObjectPath getObjectPath() const { return OBJECT_PATH_VALUE; }
 

test/integrationtests/adaptor-glue.h

@@ -82,6 +82,16 @@ protected:
             return this->sumVectorItems(a, b);
         });
 
+        object_.registerMethod("doOperationSync").onInterface(INTERFACE_NAME).implementedAs([this](uint32_t param)
+        {
+            return this->doOperationSync(param);
+        });
+
+        object_.registerMethod("doOperationAsync").onInterface(INTERFACE_NAME).implementedAs([this](sdbus::Result<uint32_t> result, uint32_t param)
+        {
+            this->doOperationAsync(param, std::move(result));
+        });
+
         object_.registerMethod("getSignature").onInterface(INTERFACE_NAME).implementedAs([this](){ return this->getSignature(); });
         object_.registerMethod("getObjectPath").onInterface(INTERFACE_NAME).implementedAs([this](){ return this->getObjectPath(); });
 
@@ -139,6 +149,8 @@ protected:
     virtual sdbus::Struct<std::string, sdbus::Struct<std::map<int32_t, int32_t>>> getStructInStruct() const = 0;
     virtual int32_t sumStructItems(const sdbus::Struct<uint8_t, uint16_t>& a, const sdbus::Struct<int32_t, int64_t>& b) = 0;
     virtual uint32_t sumVectorItems(const std::vector<uint16_t>& a, const std::vector<uint64_t>& b) = 0;
+    virtual uint32_t doOperationSync(uint32_t param) = 0;
+    virtual void doOperationAsync(uint32_t param, sdbus::Result<uint32_t> result) = 0;
     virtual sdbus::Signature getSignature() const  = 0;
     virtual sdbus::ObjectPath getObjectPath() const = 0;
     virtual ComplexType getComplex() const = 0;

test/integrationtests/proxy-glue.h

@@ -120,6 +120,20 @@ public:
         return result;
     }
 
+    uint32_t doOperationSync(uint32_t param)
+    {
+        uint32_t result;
+        object_.callMethod("doOperationSync").onInterface(INTERFACE_NAME).withArguments(param).storeResultsTo(result);
+        return result;
+    }
+
+    uint32_t doOperationAsync(uint32_t param)
+    {
+        uint32_t result;
+        object_.callMethod("doOperationAsync").onInterface(INTERFACE_NAME).withArguments(param).storeResultsTo(result);
+        return result;
+    }
+
     sdbus::Signature getSignature()
     {
         sdbus::Signature result;

test/unittests/Message_test.cpp

@@ -110,13 +110,6 @@ TEST(AMessage, IsNotEmptyWhenContainsAValue)
     ASSERT_FALSE(msg.isEmpty());
 }
 
-TEST(AMessage, ReturnsItsTypeWhenAsked)
-{
-    sdbus::Message msg{sdbus::createPlainMessage()};
-
-    ASSERT_THAT(msg.getType(), Eq(sdbus::Message::Type::ePlainMessage));
-}
-
 TEST(AMessage, CanCarryASimpleInteger)
 {
     sdbus::Message msg{sdbus::createPlainMessage()};

test/unittests/TypeTraits_test.cpp

@@ -28,6 +28,7 @@
 #include <gtest/gtest.h>
 #include <gmock/gmock.h>
 #include <cstdint>
+#include <type_traits>
 
 using ::testing::Eq;
 
@@ -127,3 +128,42 @@ TYPED_TEST(Type2DBusTypeSignatureConversion, ConvertsTypeToProperDBusSignature)
 {
     ASSERT_THAT(sdbus::signature_of<TypeParam>::str(), Eq(this->dbusTypeSignature_));
 }
+
+TEST(FreeFunctionTypeTraits, DetectsTraitsOfTrivialSignatureFunction)
+{
+    void f();
+    using Fnc = decltype(f);
+
+    static_assert(!sdbus::is_async_method_v<Fnc>, "Free function incorrectly detected as async method");
+    static_assert(std::is_same<sdbus::function_arguments_t<Fnc>, std::tuple<>>::value, "Incorrectly detected free function parameters");
+    static_assert(std::is_same<sdbus::tuple_of_function_input_arg_types_t<Fnc>, std::tuple<>>::value, "Incorrectly detected tuple of free function parameters");
+    static_assert(std::is_same<sdbus::tuple_of_function_output_arg_types_t<Fnc>, void>::value, "Incorrectly detected tuple of free function return types");
+    static_assert(sdbus::function_argument_count_v<Fnc> == 0, "Incorrectly detected free function parameter count");
+    static_assert(std::is_void<sdbus::function_result_t<Fnc>>::value, "Incorrectly detected free function return type");
+}
+
+TEST(FreeFunctionTypeTraits, DetectsTraitsOfNontrivialSignatureFunction)
+{
+    std::tuple<char, int> f(double&, const char*, int);
+    using Fnc = decltype(f);
+
+    static_assert(!sdbus::is_async_method_v<Fnc>, "Free function incorrectly detected as async method");
+    static_assert(std::is_same<sdbus::function_arguments_t<Fnc>, std::tuple<double&, const char*, int>>::value, "Incorrectly detected free function parameters");
+    static_assert(std::is_same<sdbus::tuple_of_function_input_arg_types_t<Fnc>, std::tuple<double, const char*, int>>::value, "Incorrectly detected tuple of free function parameters");
+    static_assert(std::is_same<sdbus::tuple_of_function_output_arg_types_t<Fnc>, std::tuple<char, int>>::value, "Incorrectly detected tuple of free function return types");
+    static_assert(sdbus::function_argument_count_v<Fnc> == 3, "Incorrectly detected free function parameter count");
+    static_assert(std::is_same<sdbus::function_result_t<Fnc>, std::tuple<char, int>>::value, "Incorrectly detected free function return type");
+}
+
+TEST(FreeFunctionTypeTraits, DetectsTraitsOfAsyncFunction)
+{
+    void f(sdbus::Result<char, int>, double&, const char*, int);
+    using Fnc = decltype(f);
+
+    static_assert(sdbus::is_async_method_v<Fnc>, "Free async function incorrectly detected as sync method");
+    static_assert(std::is_same<sdbus::function_arguments_t<Fnc>, std::tuple<double&, const char*, int>>::value, "Incorrectly detected free function parameters");
+    static_assert(std::is_same<sdbus::tuple_of_function_input_arg_types_t<Fnc>, std::tuple<double, const char*, int>>::value, "Incorrectly detected tuple of free function parameters");
+    static_assert(std::is_same<sdbus::tuple_of_function_output_arg_types_t<Fnc>, std::tuple<char, int>>::value, "Incorrectly detected tuple of free function return types");
+    static_assert(sdbus::function_argument_count_v<Fnc> == 3, "Incorrectly detected free function parameter count");
+    static_assert(std::is_same<sdbus::function_result_t<Fnc>, std::tuple<char, int>>::value, "Incorrectly detected free function return type");
+}