Tolstograeva_V_S_limiter

src/main/java/hse/java/lectures/lesson7/limiter/RateLimiter.java

@@ -12,15 +12,36 @@ public class RateLimiter {
      *                    (скользящее окно 1 секунда или 1 минута)
      * @param maxRequests максимум успешных {@link #check()} за окно (должно быть > 0)
      */
+
+    long[] times;
+    long window;
+    int maxRequests, head, size;
+
     public RateLimiter(ChronoUnit unit, int maxRequests) {
-        throw new UnsupportedOperationException("Not implemented");
+        if (maxRequests <= 0) throw new IllegalArgumentException();
+        if (unit != ChronoUnit.SECONDS && unit != ChronoUnit.MINUTES) throw new IllegalArgumentException();
+        this.maxRequests = maxRequests;
+        times = new long[maxRequests];
+        window = unit == ChronoUnit.MINUTES ? 60000L : 1000L;
     }
 
     /**
      * Регистрирует попытку и возвращает, разрешена ли она в пределах лимита.
      */
     public boolean check() {
-        throw new UnsupportedOperationException("Not implemented");
+        long now = System.currentTimeMillis();
+        while (size > 0 && now - times[head] >= window) {
+            if (++head == maxRequests) head = 0;
+            size -= 1;
+        }
+
+        if (size == maxRequests) return false;
+
+        int position = head + size;
+        if (position >= maxRequests) position -= maxRequests;
+        times[position] = now;
+        size += 1;
+        return true;
     }
 
 }

src/test/java/hse/java/lectures/lesson7/RateLimiterTest.java

@@ -0,0 +1,31 @@
+package hse.java.lectures.lesson7.limiter;
+
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import java.time.temporal.ChronoUnit;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+@Tag("limiter")
+public class RateLimiterTest {
+    @Test
+    void badArgs() {
+        assertThrows(IllegalArgumentException.class, () -> new RateLimiter(null, 1));
+        assertThrows(IllegalArgumentException.class, () -> new RateLimiter(ChronoUnit.HOURS, 1));
+        assertThrows(IllegalArgumentException.class, () -> new RateLimiter(ChronoUnit.SECONDS, 0));
+        assertThrows(IllegalArgumentException.class, () -> new RateLimiter(ChronoUnit.MINUTES, -1));
+    }
+
+    @Test
+    void floatingSecond() throws Exception {
+        RateLimiter limiter = new RateLimiter(ChronoUnit.SECONDS, 2);
+        assertTrue(limiter.check());
+        Thread.sleep(700);
+        assertTrue(limiter.check());
+        Thread.sleep(400);
+        assertTrue(limiter.check());
+        assertFalse(limiter.check());
+    }
+
+}