beginning of the scheduler

taskmanager/CMakeLists.txt

@@ -5,12 +5,14 @@ set(HEADERS
     manager.h
     job.h
     route.h
+    scheduler.h
 )
 
 set(SOURCES
     manager.cpp
     job.cpp
     route.cpp
+    scheduler.cpp
 )
 
 target_sources(${PROJECT_NAME} PRIVATE ${SOURCES})

taskmanager/scheduler.cpp

@@ -0,0 +1,75 @@
+//SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
+//SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "scheduler.h"
+
+TM::Scheduler::Scheduler (std::weak_ptr<Manager> manager):
+    manager(manager),
+    queue(),
+    mutex(),
+    cond(),
+    thread(nullptr),
+    running(false)
+{}
+
+TM::Scheduler::~Scheduler () {
+    stop();
+}
+
+void TM::Scheduler::start () {
+    std::unique_lock lock(mutex);
+    if (running)
+        return;
+
+    running = true;
+    thread = std::make_unique<std::thread>(&Scheduler::loop, this);
+}
+
+void TM::Scheduler::stop () {
+    std::unique_lock lock(mutex);
+    if (!running)
+        return;
+
+    running = false;
+
+    lock.unlock();
+    cond.notify_all();
+    thread->join();
+
+    lock.lock();
+    thread.reset();
+}
+
+void TM::Scheduler::loop () {
+    while (running) {
+        std::unique_lock<std::mutex> lock(mutex);
+        if (queue.empty()) {
+            cond.wait(lock);
+            continue;
+        }
+
+        Time currentTime = std::chrono::steady_clock::now();
+        while (!queue.empty()) {
+            Time nextScheduledTime = queue.top().first;
+            if (nextScheduledTime > currentTime) {
+                cond.wait_until(lock, nextScheduledTime);
+                break;
+            }
+
+            Task task = queue.top().second;
+            queue.pop();
+            lock.unlock();
+            task();
+            lock.lock();
+        }
+    }
+}
+
+void TM::Scheduler::schedule (Task task, Delay delay) {
+    std::unique_lock lock(mutex);
+    Time time = std::chrono::steady_clock::now() + delay;
+    queue.emplace(time, task);
+
+    lock.unlock();
+    cond.notify_one();
+}

taskmanager/scheduler.h

@@ -0,0 +1,48 @@
+//SPDX-FileCopyrightText: 2023 Yury Gubich <blue@macaw.me>
+//SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <memory>
+#include <thread>
+#include <queue>
+#include <chrono>
+#include <functional>
+#include <mutex>
+#include <condition_variable>
+
+#include "manager.h"
+#include "utils/helpers.h"
+
+namespace TM {
+class Scheduler {
+public:
+    using Delay = std::chrono::milliseconds;
+    using Task = std::function<void()>;
+
+    Scheduler (std::weak_ptr<Manager> manager);
+    ~Scheduler ();
+
+    void start();
+    void stop();
+    void schedule(Task task, Delay delay);
+
+private:
+    void loop();
+
+private:
+    using Time = std::chrono::time_point<std::chrono::steady_clock>;
+    using Record = std::pair<Time, Task>;
+
+    std::weak_ptr<Manager> manager;
+    std::priority_queue<
+        Record,
+        std::vector<Record>,
+        FirstGreater<Record>
+    > queue;
+    std::mutex mutex;
+    std::condition_variable cond;
+    std::unique_ptr<std::thread> thread;
+    bool running;
+};
+}