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ThiernoAmirouDialloThiernoAmirouDiallo
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Programming Challenge redislabs-training#3 
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‎src/main/java/com/redislabs/university/RU102J/api/SiteStats.java‎

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Original file line numberDiff line numberDiff line change
@@ -12,6 +12,7 @@ public class SiteStats {
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private Double minWhGenerated;
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private Double maxCapacity;
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/* These field names will be used by multiple classes, so we define
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them here to abide by DRY (don't repeat yourself). */
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public final static String reportingTimeField = "lastReportingTime";

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

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@@ -3,88 +3,98 @@
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import com.redislabs.university.RU102J.api.MeterReading;
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import com.redislabs.university.RU102J.api.SiteStats;
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import com.redislabs.university.RU102J.script.CompareAndUpdateScript;
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import redis.clients.jedis.Jedis;
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import redis.clients.jedis.JedisPool;
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import redis.clients.jedis.Transaction;
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import java.time.ZoneOffset;
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import java.time.ZonedDateTime;
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import java.util.Map;
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import redis.clients.jedis.Jedis;
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import redis.clients.jedis.JedisPool;
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import redis.clients.jedis.Transaction;
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public class SiteStatsDaoRedisImpl implements SiteStatsDao {
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private final int weekSeconds = 60 * 60 * 24 * 7;
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private final JedisPool jedisPool;
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private final CompareAndUpdateScript compareAndUpdateScript;
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public SiteStatsDaoRedisImpl(JedisPool jedisPool) {
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this.jedisPool = jedisPool;
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this.compareAndUpdateScript = new CompareAndUpdateScript(jedisPool);
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}
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// Returns the site stats for the current day
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@Override
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public SiteStats findById(long siteId) {
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return findById(siteId, ZonedDateTime.now());
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}
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@Override
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public SiteStats findById(long siteId, ZonedDateTime day) {
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try (Jedis jedis = jedisPool.getResource()) {
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String key = RedisSchema.getSiteStatsKey(siteId, day);
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Map<String, String> fields = jedis.hgetAll(key);
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if (fields == null || fields.isEmpty()) {
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return null;
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}
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return new SiteStats(fields);
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}
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}
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@Override
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public void update(MeterReading reading) {
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try (Jedis jedis = jedisPool.getResource()) {
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Long siteId = reading.getSiteId();
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ZonedDateTime day = reading.getDateTime();
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String key = RedisSchema.getSiteStatsKey(siteId, day);
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updateBasic(jedis, key, reading);
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}
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}
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// A naive implementation of update. This implementation has
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// potential race conditions and makes several round trips to Redis.
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private void updateBasic(Jedis jedis, String key, MeterReading reading) {
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String reportingTime = ZonedDateTime.now(ZoneOffset.UTC).toString();
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jedis.hset(key, SiteStats.reportingTimeField, reportingTime);
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jedis.hincrBy(key, SiteStats.countField, 1);
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jedis.expire(key, weekSeconds);
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String maxWh = jedis.hget(key, SiteStats.maxWhField);
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if (maxWh == null || reading.getWhGenerated() > Double.valueOf(maxWh)) {
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jedis.hset(key, SiteStats.maxWhField,
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String.valueOf(reading.getWhGenerated()));
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}
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String minWh = jedis.hget(key, SiteStats.minWhField);
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if (minWh == null || reading.getWhGenerated() < Double.valueOf(minWh)) {
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jedis.hset(key, SiteStats.minWhField,
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String.valueOf(reading.getWhGenerated()));
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}
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String maxCapacity = jedis.hget(key, SiteStats.maxCapacityField);
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if (maxCapacity == null || getCurrentCapacity(reading) > Double.valueOf(maxCapacity)) {
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jedis.hset(key, SiteStats.maxCapacityField,
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String.valueOf(getCurrentCapacity(reading)));
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}
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}
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// Challenge #3
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private void updateOptimized(Jedis jedis, String key, MeterReading reading) {
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// START Challenge #3
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// END Challenge #3
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}
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private Double getCurrentCapacity(MeterReading reading) {
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return reading.getWhGenerated() - reading.getWhUsed();
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}
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private final int weekSeconds = 60 * 60 * 24 * 7;
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private final JedisPool jedisPool;
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private final CompareAndUpdateScript compareAndUpdateScript;
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public SiteStatsDaoRedisImpl( JedisPool jedisPool ) {
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this.jedisPool = jedisPool;
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this.compareAndUpdateScript = new CompareAndUpdateScript( jedisPool );
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}
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// Returns the site stats for the current day
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@Override
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public SiteStats findById( long siteId ) {
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return findById( siteId, ZonedDateTime.now() );
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}
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@Override
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public SiteStats findById( long siteId, ZonedDateTime day ) {
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try ( Jedis jedis = jedisPool.getResource() ) {
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String key = RedisSchema.getSiteStatsKey( siteId, day );
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Map<String, String> fields = jedis.hgetAll( key );
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if ( fields == null || fields.isEmpty() ) {
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return null;
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}
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return new SiteStats( fields );
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}
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}
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@Override
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public void update( MeterReading reading ) {
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try ( Jedis jedis = jedisPool.getResource() ) {
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Long siteId = reading.getSiteId();
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ZonedDateTime day = reading.getDateTime();
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String key = RedisSchema.getSiteStatsKey( siteId, day );
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updateOptimized( jedis, key, reading );
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}
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}
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// A naive implementation of update. This implementation has
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// potential race conditions and makes several round trips to Redis.
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private void updateBasic( Jedis jedis, String key, MeterReading reading ) {
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String reportingTime = ZonedDateTime.now( ZoneOffset.UTC ).toString();
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jedis.hset( key, SiteStats.reportingTimeField, reportingTime );
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jedis.hincrBy( key, SiteStats.countField, 1 );
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jedis.expire( key, weekSeconds );
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String maxWh = jedis.hget( key, SiteStats.maxWhField );
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if ( maxWh == null || reading.getWhGenerated() > Double.valueOf( maxWh ) ) {
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jedis.hset( key, SiteStats.maxWhField, String.valueOf( reading.getWhGenerated() ) );
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}
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String minWh = jedis.hget( key, SiteStats.minWhField );
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if ( minWh == null || reading.getWhGenerated() < Double.valueOf( minWh ) ) {
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jedis.hset( key, SiteStats.minWhField, String.valueOf( reading.getWhGenerated() ) );
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}
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String maxCapacity = jedis.hget( key, SiteStats.maxCapacityField );
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if ( maxCapacity == null || getCurrentCapacity( reading ) > Double.valueOf( maxCapacity ) ) {
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jedis.hset( key, SiteStats.maxCapacityField, String.valueOf( getCurrentCapacity( reading ) ) );
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}
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}
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// Challenge #3
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private void updateOptimized( Jedis jedis, String key, MeterReading reading ) {
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String reportingTime = ZonedDateTime.now( ZoneOffset.UTC ).toString();
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jedis.hset( key, SiteStats.reportingTimeField, reportingTime );
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jedis.hincrBy( key, SiteStats.countField, 1 );
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jedis.expire( key, weekSeconds );
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Transaction transaction = jedis.multi();
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compareAndUpdateScript.updateIfGreater( transaction, key, SiteStats.maxWhField, reading.getWhGenerated() );
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compareAndUpdateScript.updateIfLess( transaction, key, SiteStats.minWhField, reading.getWhGenerated() );
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compareAndUpdateScript.updateIfGreater( transaction, key, SiteStats.maxCapacityField, getCurrentCapacity( reading ) );
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transaction.exec();
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transaction.close();
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}
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private Double getCurrentCapacity( MeterReading reading ) {
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return reading.getWhGenerated() - reading.getWhUsed();
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}
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}

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