Merge remote-tracking branch 'upstream/master'

core-java-arrays/src/main/java/com/baeldung/arrays/ParallelPrefixBenchmark.java

@@ -0,0 +1,44 @@
+package com.baeldung.arrays;
+
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.infra.Blackhole;
+
+import java.util.Arrays;
+
+public class ParallelPrefixBenchmark {
+  private static final int ARRAY_SIZE = 200_000_000;
+
+  @State(Scope.Benchmark)
+  public static class BigArray {
+
+    int[] data;
+
+    @Setup(Level.Iteration)
+    public void prepare() {
+      data = new int[ARRAY_SIZE];
+      for(int j = 0; j< ARRAY_SIZE; j++) {
+        data[j] = 1;
+      }
+    }
+
+    @TearDown(Level.Iteration)
+    public void destroy() {
+      data = null;
+    }
+
+  }
+
+  @Benchmark
+  public void largeArrayLoopSum(BigArray bigArray, Blackhole blackhole) {
+    for (int i = 0; i < ARRAY_SIZE - 1; i++) {
+      bigArray.data[i + 1] += bigArray.data[i];
+    }
+    blackhole.consume(bigArray.data);
+  }
+
+  @Benchmark
+  public void largeArrayParallelPrefixSum(BigArray bigArray, Blackhole blackhole) {
+    Arrays.parallelPrefix(bigArray.data, (left, right) -> left + right);
+    blackhole.consume(bigArray.data);
+  }
+}

core-java-arrays/src/test/java/com/baeldung/arrays/ArraysUnitTest.java

@@ -1,5 +1,7 @@
 package com.baeldung.arrays;
 
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.*;
 
 import org.junit.Before;
@@ -9,6 +11,7 @@ import org.junit.rules.ExpectedException;
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.Random;
 import java.util.stream.Stream;
 
 public class ArraysUnitTest {
@@ -150,4 +153,52 @@ public class ArraysUnitTest {
         exception.expect(UnsupportedOperationException.class);
         rets.add("the");
     }
+
+    @Test
+    public void givenIntArray_whenPrefixAdd_thenAllAccumulated() {
+        int[] arri = new int[] { 1, 2, 3, 4};
+        Arrays.parallelPrefix(arri, (left, right) -> left + right);
+        assertThat(arri, is(new int[] { 1, 3, 6, 10}));
+    }
+
+    @Test
+    public void givenStringArray_whenPrefixConcat_thenAllMerged() {
+        String[] arrs = new String[] { "1", "2", "3" };
+        Arrays.parallelPrefix(arrs, (left, right) -> left + right);
+        assertThat(arrs, is(new String[] { "1", "12", "123" }));
+    }
+
+    @Test
+    public void whenPrefixAddWithRange_thenRangeAdded() {
+        int[] arri = new int[] { 1, 2, 3, 4, 5 };
+        Arrays.parallelPrefix(arri, 1, 4, (left, right) -> left + right);
+        assertThat(arri, is(new int[] { 1, 2, 5, 9, 5 }));
+    }
+
+    @Test
+    public void whenPrefixNonAssociative_thenError() {
+        boolean consistent = true;
+        Random r = new Random();
+        for (int k = 0; k < 100_000; k++) {
+            int[] arrA = r.ints(100, 1, 5).toArray();
+            int[] arrB = Arrays.copyOf(arrA, arrA.length);
+
+            Arrays.parallelPrefix(arrA, this::nonassociativeFunc);
+
+            for (int i = 1; i < arrB.length; i++) {
+                arrB[i] = nonassociativeFunc(arrB[i - 1], arrB[i]);
+            }
+            consistent = Arrays.equals(arrA, arrB);
+            if(!consistent) break;
+        }
+        assertFalse(consistent);
+    }
+
+    /**
+     * non-associative int binary operator
+     */
+    private int nonassociativeFunc(int left, int right) {
+        return left + right*left;
+    }
+
 }

spring-ehcache/src/main/java/com/baeldung/cachetest/config/CacheConfig.java

@@ -1,57 +1,10 @@
 package com.baeldung.cachetest.config;
 
-import java.math.BigDecimal;
-import java.time.Duration;
-
-import javax.cache.CacheManager;
-
-import org.ehcache.config.CacheConfiguration;
-import org.ehcache.config.ResourcePools;
-import org.ehcache.config.builders.CacheConfigurationBuilder;
-import org.ehcache.config.builders.CacheEventListenerConfigurationBuilder;
-import org.ehcache.config.builders.ExpiryPolicyBuilder;
-import org.ehcache.config.builders.ResourcePoolsBuilder;
-import org.ehcache.config.units.EntryUnit;
-import org.ehcache.config.units.MemoryUnit;
-import org.ehcache.event.EventType;
-import org.ehcache.jsr107.Eh107Configuration;
-import org.springframework.boot.autoconfigure.cache.JCacheManagerCustomizer;
 import org.springframework.cache.annotation.EnableCaching;
-import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
 @Configuration
 @EnableCaching
 public class CacheConfig {
-
+ 
-	private static final int ON_HEAP_CACHE_SIZE_ENTRIES = 2;
-	private static final int OFF_HEAP_CACHE_SIZE_MB = 10;
-	private static final int CACHE_EXPIRY_SECONDS = 30;
-
-	@Bean
-	public JCacheManagerCustomizer jcacheManagerCustomizer() {
-		return new JCacheManagerCustomizer() {
-
-			@Override
-			public void customize(CacheManager cacheManager) {
-				ResourcePools resourcePools = ResourcePoolsBuilder.newResourcePoolsBuilder()
-						.heap(ON_HEAP_CACHE_SIZE_ENTRIES, EntryUnit.ENTRIES)
-						.offheap(OFF_HEAP_CACHE_SIZE_MB, MemoryUnit.MB).build();
-
-				CacheEventListenerConfigurationBuilder eventLoggerConfig = CacheEventListenerConfigurationBuilder
-						.newEventListenerConfiguration(new CacheEventLogger(), EventType.CREATED, EventType.EXPIRED)
-						.unordered().asynchronous();
-
-				CacheConfiguration<?, ?> cacheConfiguration = CacheConfigurationBuilder
-						.newCacheConfigurationBuilder(Long.class, BigDecimal.class, resourcePools)
-						.withExpiry(ExpiryPolicyBuilder.timeToLiveExpiration(Duration.ofSeconds(CACHE_EXPIRY_SECONDS)))
-						.add(eventLoggerConfig).build();
-
-				cacheManager.createCache("squareCache",
-						Eh107Configuration.fromEhcacheCacheConfiguration(cacheConfiguration));
-
-			}
-		};
-	}
-
 }

spring-ehcache/src/main/java/com/baeldung/cachetest/config/CacheEventLogger.java

@@ -7,12 +7,11 @@ import org.slf4j.LoggerFactory;
 
 public class CacheEventLogger implements CacheEventListener<Object, Object> {
 
-	private static final Logger log = LoggerFactory.getLogger(CacheEventLogger.class);
+    private static final Logger log = LoggerFactory.getLogger(CacheEventLogger.class);
 
-	@Override
+    @Override
-	public void onEvent(CacheEvent<? extends Object, ? extends Object> cacheEvent) {
+    public void onEvent(CacheEvent<? extends Object, ? extends Object> cacheEvent) {
-		log.info("Cache event {} for item with key {}. Old value = {}, New value = {}", cacheEvent.getType(),
+        log.info("Cache event {} for item with key {}. Old value = {}, New value = {}", cacheEvent.getType(), cacheEvent.getKey(), cacheEvent.getOldValue(), cacheEvent.getNewValue());
-				cacheEvent.getKey(), cacheEvent.getOldValue(), cacheEvent.getNewValue());
+    }
-	}
 
 }

spring-ehcache/src/main/java/com/baeldung/cachetest/rest/NumberController.java

@@ -15,15 +15,15 @@ import com.baeldung.cachetest.service.NumberService;
 @RequestMapping(path = "/number", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
 public class NumberController {
 
-	private final static Logger log = LoggerFactory.getLogger(NumberController.class);
+    private final static Logger log = LoggerFactory.getLogger(NumberController.class);
 
-	@Autowired
+    @Autowired
-	private NumberService numberService;
+    private NumberService numberService;
 
-	@GetMapping(path = "/square/{number}")
+    @GetMapping(path = "/square/{number}")
-	public String getThing(@PathVariable Long number) {
+    public String getThing(@PathVariable Long number) {
-		log.info("call numberService to square {}", number);
+        log.info("call numberService to square {}", number);
-		return String.format("{\"square\": %s}", numberService.square(number));
+        return String.format("{\"square\": %s}", numberService.square(number));
-	}
+    }
 
 }

spring-ehcache/src/main/java/com/baeldung/cachetest/service/NumberService.java

@@ -10,13 +10,14 @@ import org.springframework.stereotype.Service;
 @Service
 public class NumberService {
 
-	private final static Logger log = LoggerFactory.getLogger(NumberService.class);
+    private final static Logger log = LoggerFactory.getLogger(NumberService.class);
 
-	@Cacheable(value = "squareCache", key = "#number", condition = "#number>10")
+    @Cacheable(value = "squareCache", key = "#number", condition = "#number>10")
-	public BigDecimal square(Long number) {
+    public BigDecimal square(Long number) {
-		BigDecimal square = BigDecimal.valueOf(number).multiply(BigDecimal.valueOf(number));
+        BigDecimal square = BigDecimal.valueOf(number)
-		log.info("square of {} is {}", number, square);
+            .multiply(BigDecimal.valueOf(number));
-		return square;
+        log.info("square of {} is {}", number, square);
-	}
+        return square;
+    }
 
 }

spring-ehcache/src/main/resources/application.properties

@@ -0,0 +1 @@
+spring.cache.jcache.config=classpath:ehcache.xml

spring-ehcache/src/main/resources/ehcache.xml

@@ -0,0 +1,31 @@
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="http://www.ehcache.org/v3"
+    xmlns:jsr107="http://www.ehcache.org/v3/jsr107"
+    xsi:schemaLocation="
+            http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.0.xsd
+            http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.0.xsd">
+
+    <cache alias="squareCache">
+        <key-type>java.lang.Long</key-type>
+        <value-type>java.math.BigDecimal</value-type>
+        <expiry>
+            <ttl unit="seconds">30</ttl>
+        </expiry>
+
+        <listeners>
+            <listener>
+                <class>com.baeldung.cachetest.config.CacheEventLogger</class>
+                <event-firing-mode>ASYNCHRONOUS</event-firing-mode>
+                <event-ordering-mode>UNORDERED</event-ordering-mode>
+                <events-to-fire-on>CREATED</events-to-fire-on>
+                <events-to-fire-on>EXPIRED</events-to-fire-on>
+            </listener>
+        </listeners>
+
+        <resources>
+            <heap unit="entries">2</heap>
+            <offheap unit="MB">10</offheap>
+        </resources>
+    </cache>
+
+</config>