Add first version

[ric-plt/sdl.git] / src / eventfd.cpp

diff --git a/src/eventfd.cpp b/src/eventfd.cpp
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+++ b/src/eventfd.cpp
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+/*
+   Copyright (c) 2018-2019 Nokia.
+
+   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 "private/eventfd.hpp"
+#include <sys/eventfd.h>
+#include "private/abort.hpp"
+#include "private/engine.hpp"
+#include "private/system.hpp"
+
+using namespace shareddatalayer;
+
+namespace
+{
+    /*
+     * Simple wrapper for executing the given callback without expecting
+     * exceptions. If callback throws, we'll crash.
+     */
+    void execute(const EventFD::Callback& callback) noexcept
+    {
+        callback();
+    }
+}
+
+EventFD::EventFD(Engine& engine):
+    EventFD(System::getSystem(), engine)
+{
+}
+
+EventFD::EventFD(System& system, Engine& engine):
+    system(system),
+    fd(system, system.eventfd(0U, EFD_CLOEXEC | EFD_NONBLOCK))
+{
+    engine.addMonitoredFD(fd, Engine::EVENT_IN, std::bind(&EventFD::handleEvents, this));
+}
+
+EventFD::~EventFD()
+{
+}
+
+void EventFD::post(const Callback& callback)
+{
+    if (!callback)
+        SHAREDDATALAYER_ABORT("A null callback was provided");
+
+    atomicPushBack(callback);
+    static const uint64_t value(1U);
+    system.write(fd, &value, sizeof(value));
+}
+
+void EventFD::atomicPushBack(const Callback& callback)
+{
+    std::lock_guard<std::mutex> guard(callbacksMutex);
+    callbacks.push_back(callback);
+}
+
+EventFD::Callbacks EventFD::atomicPopAll()
+{
+    std::lock_guard<std::mutex> guard(callbacksMutex);
+    Callbacks extractedCallbacks;
+    std::swap(callbacks, extractedCallbacks);
+    return extractedCallbacks;
+}
+
+void EventFD::handleEvents()
+{
+    uint64_t value;
+    system.read(fd, &value, sizeof(value));
+    executeCallbacks();
+}
+
+void EventFD::executeCallbacks()
+{
+    Callbacks callbacks(atomicPopAll());
+    while (!callbacks.empty())
+        popAndExecuteFirstCallback(callbacks);
+}
+
+void EventFD::popAndExecuteFirstCallback(Callbacks& callbacks)
+{
+    const auto callback(callbacks.front());
+    callbacks.pop_front();
+    execute(callback);
+}