feat: Implement API for event loop and timers.

Ticket: MEN-6127
Changelog: None

Signed-off-by: Kristian Amlie <[email protected]>

.gitignore

@@ -37,7 +37,7 @@
 *.dirstamp
 
 # Test binaries
-*_test*
+*_test
 
 # Build artifacts
 /mender

.gitlab-ci.yml

@@ -21,7 +21,7 @@ test:
   stage: test
   image: debian:11
   before_script:
-    - apt update && apt install -yyq g++ cmake git make lcov pkg-config liblmdb++-dev
+    - apt update && apt install -yyq g++ cmake git make lcov pkg-config liblmdb++-dev libboost-dev
   script:
     - cmake .
     - make coverage

common/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(json_sources "$<$<STREQUAL:${PLATFORM},linux_x86>:nlohmann/nlohmann_json.cpp>")
 set(kv_db_sources "$<$<STREQUAL:${PLATFORM},linux_x86>:lmdb/lmdb_kv_db.cpp>")
+set(events_sources "$<$<STREQUAL:${PLATFORM},linux_x86>:boost/events.cpp>")
 
 add_library(common_json STATIC json/platform/${json_sources})
 target_include_directories(common_json PRIVATE ../)
@@ -23,3 +24,13 @@ if(${kv_db_sources} MATCHES ".*lmdb.*")
 	target_link_libraries(common_kv_db PUBLIC "${LMDB_LIB}")
   endif()
 endif()
+
+add_library(common_events STATIC events/platform/${events_sources})
+target_include_directories(common_events PRIVATE ../)
+target_compile_options(common_events PUBLIC -DMENDER_EVENTS_USE_BOOST=1)
+
+add_executable(events_test EXCLUDE_FROM_ALL events_test.cpp)
+target_link_libraries(events_test PUBLIC common_events GTest::gtest_main)
+target_include_directories(events_test PRIVATE ../)
+gtest_discover_tests(events_test)
+add_dependencies(check events_test)

common/events.hpp

@@ -0,0 +1,67 @@
+// Copyright 2023 Northern.tech AS
+//
+//    Licensed under the Apache License, Version 2.0 (the "License");
+//    you may not use this file except in compliance with the License.
+//    You may obtain a copy of the License at
+//
+//        http://www.apache.org/licenses/LICENSE-2.0
+//
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+
+#include <functional>
+#include <system_error>
+
+typedef std::function<void(std::error_code)> EventHandler;
+
+#ifdef MENDER_EVENTS_USE_BOOST
+#include <boost/asio.hpp>
+#endif // MENDER_EVENTS_USE_BOOST
+
+namespace mender::events {
+
+#ifdef MENDER_EVENTS_USE_BOOST
+namespace asio = boost::asio;
+#endif // MENDER_EVENTS_USE_BOOST
+
+class EventLoop {
+public:
+	void Run();
+	void Stop();
+
+private:
+#ifdef MENDER_EVENTS_USE_BOOST
+	asio::io_context ctx_;
+
+	friend class Timer;
+#endif // MENDER_EVENTS_USE_BOOST
+};
+
+class Timer {
+public:
+	Timer(EventLoop &loop);
+
+	template <typename Duration>
+	void Wait(Duration duration) {
+		timer_.expires_after(duration);
+		timer_.wait();
+	}
+
+	template <typename Duration>
+	void AsyncWait(Duration duration, EventHandler handler) {
+		timer_.expires_after(duration);
+		timer_.async_wait(handler);
+	}
+
+	void Cancel();
+
+private:
+#ifdef MENDER_EVENTS_USE_BOOST
+	asio::steady_timer timer_;
+#endif // MENDER_EVENTS_USE_BOOST
+};
+
+} // namespace mender::events

common/events/platform/boost/events.cpp

@@ -0,0 +1,39 @@
+// Copyright 2023 Northern.tech AS
+//
+//    Licensed under the Apache License, Version 2.0 (the "License");
+//    you may not use this file except in compliance with the License.
+//    You may obtain a copy of the License at
+//
+//        http://www.apache.org/licenses/LICENSE-2.0
+//
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+
+#include <common/events.hpp>
+
+#include <boost/asio.hpp>
+
+namespace asio = boost::asio;
+
+namespace mender::events {
+
+void EventLoop::Run() {
+	ctx_.run();
+}
+
+void EventLoop::Stop() {
+	ctx_.stop();
+}
+
+Timer::Timer(EventLoop &loop) :
+	timer_(loop.ctx_) {
+}
+
+void Timer::Cancel() {
+	timer_.cancel();
+}
+
+} // namespace mender::events

common/events_test.cpp

@@ -0,0 +1,111 @@
+// Copyright 2023 Northern.tech AS
+//
+//    Licensed under the Apache License, Version 2.0 (the "License");
+//    you may not use this file except in compliance with the License.
+//    You may obtain a copy of the License at
+//
+//        http://www.apache.org/licenses/LICENSE-2.0
+//
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+
+#include <common/events.hpp>
+
+#include <gtest/gtest.h>
+
+#include <thread>
+#include <array>
+
+namespace events = mender::events;
+
+TEST(Events, Timers) {
+	using std::chrono::seconds;
+	using std::chrono::steady_clock;
+
+	auto short_wait = seconds(1);
+	auto medium_wait = seconds(5);
+	auto long_wait = seconds(10);
+
+	// Since we'll be waiting quite a bit, run test cases in parallel.
+	std::thread test_threads[] = {
+		// Synchronous wait.
+		std::thread([&]() {
+			auto check_point = steady_clock::now();
+			events::EventLoop loop;
+			events::Timer timer(loop);
+
+			timer.Wait(short_wait);
+			EXPECT_GE(steady_clock::now(), check_point + short_wait);
+		}),
+
+		// Asynchronous wait.
+		std::thread([&]() {
+			auto check_point = steady_clock::now();
+			events::EventLoop loop;
+			events::Timer timer(loop);
+
+			timer.AsyncWait(short_wait, [](std::error_code ec) {});
+			loop.Run();
+			EXPECT_GE(steady_clock::now(), check_point + short_wait);
+		}),
+
+		// Asynchronous wait with cancel.
+		std::thread([&]() {
+			auto check_point = steady_clock::now();
+			events::EventLoop loop;
+			events::Timer timer(loop);
+
+			timer.AsyncWait(long_wait, [](std::error_code ec) {});
+			timer.Cancel();
+			loop.Run();
+			EXPECT_LT(steady_clock::now(), check_point + long_wait);
+		}),
+
+		// Two asynchronous waits.
+		std::thread([&]() {
+			auto check_point = steady_clock::now();
+			events::EventLoop loop;
+			events::Timer timer(loop);
+			events::Timer timer2(loop);
+
+			timer.AsyncWait(short_wait, [](std::error_code ec) {});
+			timer2.AsyncWait(medium_wait, [](std::error_code ec) {});
+			loop.Run();
+			EXPECT_GE(steady_clock::now(), check_point + medium_wait);
+		}),
+
+		// Two asynchronous waits with cancel.
+		std::thread([&]() {
+			auto check_point = steady_clock::now();
+			events::EventLoop loop;
+			events::Timer timer(loop);
+			events::Timer timer2(loop);
+
+			timer.AsyncWait(short_wait, [&timer2](std::error_code ec) { timer2.Cancel(); });
+			timer2.AsyncWait(long_wait, [](std::error_code ec) {});
+			loop.Run();
+			EXPECT_GE(steady_clock::now(), check_point + short_wait);
+			EXPECT_LT(steady_clock::now(), check_point + long_wait);
+		}),
+
+		// Stop event loop.
+		std::thread([&]() {
+			auto check_point = steady_clock::now();
+			events::EventLoop loop;
+			events::Timer timer(loop);
+			events::Timer timer2(loop);
+
+			timer.AsyncWait(short_wait, [&loop](std::error_code ec) { loop.Stop(); });
+			timer2.AsyncWait(long_wait, [](std::error_code ec) {});
+			loop.Run();
+			EXPECT_GE(steady_clock::now(), check_point + short_wait);
+			EXPECT_LT(steady_clock::now(), check_point + long_wait);
+		}),
+	};
+	for (auto &thr : test_threads) {
+		thr.join();
+	}
+}

tests/Dockerfile.daemon

@@ -3,7 +3,7 @@
 FROM ubuntu:20.04 AS build
 
 ENV DEBIAN_FRONTEND=noninteractive
-RUN apt update && apt install -y cmake make git build-essential jq curl pkg-config liblmdb++-dev
+RUN apt update && apt install -y cmake make git build-essential jq curl pkg-config liblmdb++-dev libboost-dev
 
 WORKDIR /cpp/src/github.com/mendersoftware/mender
 COPY ./ .