Programming Challenge redislabs-training#7

Author: ThiernoAmirouDiallo

src/main/java/com/redislabs/university/RU102J/dao/RateLimiterSlidingDaoRedisImpl.java

@@ -1,24 +1,46 @@
 package com.redislabs.university.RU102J.dao;
 
+import com.redislabs.university.RU102J.core.KeyHelper;
+
+import java.time.ZonedDateTime;
+import java.util.UUID;
+
+import redis.clients.jedis.Jedis;
 import redis.clients.jedis.JedisPool;
+import redis.clients.jedis.Response;
+import redis.clients.jedis.Transaction;
 
 public class RateLimiterSlidingDaoRedisImpl implements RateLimiter {
 
-    private final JedisPool jedisPool;
-    private final long windowSizeMS;
-    private final long maxHits;
-
-    public RateLimiterSlidingDaoRedisImpl(JedisPool pool, long windowSizeMS,
-                                          long maxHits) {
-        this.jedisPool = pool;
-        this.windowSizeMS = windowSizeMS;
-        this.maxHits = maxHits;
-    }
-
-    // Challenge #7
-    @Override
-    public void hit(String name) throws RateLimitExceededException {
-        // START CHALLENGE #7
-        // END CHALLENGE #7
-    }
+	private final JedisPool jedisPool;
+	private final long windowSizeMS;
+	private final long maxHits;
+
+	public RateLimiterSlidingDaoRedisImpl( JedisPool pool, long windowSizeMS, long maxHits ) {
+		this.jedisPool = pool;
+		this.windowSizeMS = windowSizeMS;
+		this.maxHits = maxHits;
+	}
+
+	// Challenge #7
+	@Override
+	public void hit( String name ) throws RateLimitExceededException {
+		// START CHALLENGE #7
+		try ( Jedis jedis = jedisPool.getResource(); Transaction t = jedis.multi() ) {
+			long currentMs = ZonedDateTime.now().toInstant().toEpochMilli();
+
+			// make the member unique in order not to replace the score of another one
+			String member = String.format( "%s:%s", currentMs, UUID.randomUUID() );
+			String key = KeyHelper.getKey( String.format( "limiter:%s:%s:maxHits", windowSizeMS, name ) );
+			t.zadd( key, currentMs, member );
+			t.zremrangeByScore( key, 0, currentMs - windowSizeMS ); // remove hits before the current sliding window
+			Response<Long> hitCount = t.zcard( key );
+			t.exec();
+
+			if ( hitCount.get() > maxHits ) {
+				throw new RateLimitExceededException();
+			}
+		}
+		// END CHALLENGE #7
+	}
 }

src/test/java/com/redislabs/university/RU102J/dao/RateLimiterSlidingDaoRedisImplTest.java

@@ -47,7 +47,6 @@ public void flush() {
         keyManager.deleteKeys(jedis);
     }
 
-    @Ignore
     @Test
     public void hit() {
         int exceptionCount = 0;
@@ -64,7 +63,6 @@ public void hit() {
         assertThat(exceptionCount, is(0));
     }
 
-    @Ignore
     @Test
     public void hitOutsideLimit() {
         int exceptionCount = 0;
@@ -81,7 +79,6 @@ public void hitOutsideLimit() {
         assertThat(exceptionCount, is(2));
     }
 
-    @Ignore
     @Test
     public void hitOutsideWindow() throws InterruptedException {
         int exceptionCount = 0;