Шишигин Степан

Main.java

@@ -0,0 +1,158 @@
+package org.example;
+
+import java.util.*;
+import java.util.concurrent.*;
+
+class Main {
+    public static void main(String[] args) throws InterruptedException {
+        var random = new Random();
+        var gs = new GradingSystem();
+        var students = new ArrayList<Student>(5);
+        for (var i = 0; i < 5; i++) {
+            students.add(new Student(gs, "student" + i));
+        }
+
+        var gsTread = new Thread(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    gs.startGrading();
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        });
+        gsTread.start();
+
+        ExecutorService studentExec = Executors.newFixedThreadPool(4);
+
+        while (true) {
+            var nextStudent = students.get(random.nextInt(0, 5));
+            studentExec.execute(nextStudent::doHW);
+        }
+
+    }
+}
+
+
+class Student {
+    public String name = "noname";
+    private final GradingSystem gs;
+
+    private Semaphore hwDoing = new Semaphore(1);
+
+    public Student(GradingSystem gs, String name) {
+        this.gs = gs;
+        this.name = name;
+    }
+
+    private static HomeWork getNewHW() {
+        var random = new Random();
+        return new HomeWork(random.nextInt(10000, 15000), random.nextInt(0, 150), random.nextInt(2000, 3000));
+    }
+
+    public void doHW() {
+        try {
+            hwDoing.acquire();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        var newHW = getNewHW();
+        try {
+            System.out.println(this.name + " is doing hw" + newHW.hwId());
+            Thread.sleep(newHW.msWorkTime());
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        var hwResult = new HomeWorkResult(newHW, this);
+        hwDoing.release();
+        gs.getHWFromStudent(hwResult);
+    }
+}
+
+class GradingSystem {
+    private final Stack<Grader> graders = new Stack<>();
+    private final PriorityBlockingQueue<HomeWorkResult> hwToGrade = new PriorityBlockingQueue<>(1000, Comparator.comparingInt(hw -> hw.hw().deadline()));
+
+    private final ExecutorService gradingExecutor = Executors.newFixedThreadPool(2);
+    public final List<HomeWorkGraded> gradedHWs = new ArrayList<>();
+
+    public GradingSystem() {
+        for (int i = 0; i < 14; i++) {
+            this.graders.push(
+                    new Grader(this, "grader" + 1)
+            );
+        }
+
+    }
+
+    public void getHWFromStudent(HomeWorkResult hw) {
+        hwToGrade.add(hw);
+    }
+
+
+    public void startGrading() throws InterruptedException {
+        while (true) {
+            if (this.hwToGrade.isEmpty()) continue;
+            Grader grader;
+            try {
+                grader = this.graders.pop();
+            } catch (EmptyStackException e) {
+                Thread.sleep(100);
+                System.out.println("Пока что нет свободных проверяющих, домашек в очереди на оценку:" + this.hwToGrade.size());
+                continue;
+            }
+            var hwToCheck = this.hwToGrade.poll();
+            if (hwToCheck == null) {
+                Thread.sleep(100);
+                System.out.println("Nothing to check");
+                continue;
+            }
+            gradingExecutor.execute(() -> {
+                try {
+                    grader.grade(hwToCheck);
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                }
+            });
+            this.graders.addLast(grader);
+        }
+    }
+}
+
+class Grader {
+    private static GradingSystem gs;
+    private String name = "noname";
+
+    public Grader(GradingSystem gs, String name) {
+        this.name = name;
+        this.gs = gs;
+    }
+
+    private final Semaphore gradingSemaphore = new Semaphore(1);
+    private final Random random = new Random();
+    final int timeToGrade = 1500;
+
+    public void grade(HomeWorkResult hw) throws InterruptedException {
+        this.gradingSemaphore.acquire();
+        System.out.println(this.name + " is grading hw" + hw.hw().hwId() + " by " + hw.student().name);
+        Thread.sleep(timeToGrade);
+        this.gradingSemaphore.release();
+        gs.gradedHWs.add(
+                new HomeWorkGraded(
+                        hw,
+                        random.nextInt(0, 5)
+                )
+        );
+    }
+
+}
+
+record HomeWork(int deadline, int hwId, int msWorkTime) {
+}
+
+record HomeWorkResult(HomeWork hw, Student student) {
+}
+
+record HomeWorkGraded(HomeWorkResult hw, int grade) {
+}