feat: get all read-only values from cacheMap

Author: samvazquez

src/main/java/org/dataloader/CacheMap.java

@@ -19,6 +19,7 @@
 import org.dataloader.annotations.PublicSpi;
 import org.dataloader.impl.DefaultCacheMap;
 
+import java.util.Collection;
 import java.util.concurrent.CompletableFuture;
 
 /**
@@ -73,6 +74,12 @@ static <K, V> CacheMap<K, V> simpleMap() {
      */
     CompletableFuture<V> get(K key);
 
+    /**
+     * Gets a collection of CompletableFutures of the cache map.
+     * @return the collection of cached values
+     */
+    Collection<CompletableFuture<V>> getAll();
+
     /**
      * Creates a new cache map entry with the specified key and value, or updates the value if the key already exists.
      *

src/main/java/org/dataloader/DataLoader.java

@@ -25,10 +25,7 @@
 import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.Optional;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;
 
@@ -452,6 +449,13 @@ public Duration getTimeSinceDispatch() {
         return Duration.between(helper.getLastDispatchTime(), helper.now());
     }
 
+    /**
+     * This returns a read-only collection of CompletableFutures of the cache map.
+     * @return read-only collection of CompletableFutures
+     */
+    public Collection<CompletableFuture<V>> getCacheFutures() {
+        return helper.getCacheFutures();
+    }
 
     /**
      * Requests to load the data with the specified key asynchronously, and returns a future of the resulting value.

src/main/java/org/dataloader/DataLoaderHelper.java

@@ -7,13 +7,7 @@
 
 import java.time.Clock;
 import java.time.Instant;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.LinkedHashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.CompletionStage;
@@ -99,6 +93,10 @@ public Instant getLastDispatchTime() {
         return lastDispatchTime.get();
     }
 
+    public Collection<CompletableFuture<V>> getCacheFutures() {
+        return Collections.unmodifiableCollection(futureCache.getAll());
+    }
+
     Optional<CompletableFuture<V>> getIfPresent(K key) {
         synchronized (dataLoader) {
             boolean cachingEnabled = loaderOptions.cachingEnabled();

src/main/java/org/dataloader/impl/DefaultCacheMap.java

@@ -19,8 +19,7 @@
 import org.dataloader.CacheMap;
 import org.dataloader.annotations.Internal;
 
-import java.util.HashMap;
-import java.util.Map;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 
 /**
@@ -60,6 +59,14 @@ public CompletableFuture<V> get(K key) {
         return cache.get(key);
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public Collection<CompletableFuture<V>> getAll() {
+        return cache.values();
+    }
+
     /**
      * {@inheritDoc}
      */

src/test/java/ReadmeExamples.java

@@ -16,10 +16,7 @@
 import org.dataloader.stats.ThreadLocalStatisticsCollector;
 
 import java.time.Duration;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
 import java.util.stream.Collectors;
@@ -221,6 +218,11 @@ public CompletableFuture<Object> get(Object key) {
             return null;
         }
 
+        @Override
+        public Collection<CompletableFuture<Object>> getAll() {
+            return null;
+        }
+
         @Override
         public CacheMap set(Object key, CompletableFuture value) {
             return null;

src/test/java/org/dataloader/DataLoaderCacheMapTest.java

@@ -0,0 +1,60 @@
+package org.dataloader;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+
+import static org.dataloader.DataLoaderFactory.newDataLoader;
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for cacheMap functionality..
+ */
+public class DataLoaderCacheMapTest {
+
+    private <T> BatchLoader<T, T> keysAsValues() {
+        return CompletableFuture::completedFuture;
+    }
+
+    @Test
+    public void should_provide_all_futures_from_cache() {
+        DataLoader<Integer, Integer> dataLoader = newDataLoader(keysAsValues());
+
+        dataLoader.load(1);
+        dataLoader.load(2);
+        dataLoader.load(1);
+
+        Collection<CompletableFuture<Integer>> futures = dataLoader.getCacheFutures();
+        assertThat(futures.size(), equalTo(2));
+    }
+
+    @Test
+    public void should_access_to_future_dependants() {
+        DataLoader<Integer, Integer> dataLoader = newDataLoader(keysAsValues());
+
+        dataLoader.load(1).handle((v, t) -> t);
+        dataLoader.load(2).handle((v, t) -> t);
+        dataLoader.load(1).handle((v, t) -> t);
+
+        Collection<CompletableFuture<Integer>> futures = dataLoader.getCacheFutures();
+
+        List<CompletableFuture<Integer>> futuresList = new ArrayList<>(futures);
+        assertThat(futuresList.get(0).getNumberOfDependents(), equalTo(2));
+        assertThat(futuresList.get(1).getNumberOfDependents(), equalTo(1));
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void should_throw_exception__on_mutation_attempt() {
+        DataLoader<Integer, Integer> dataLoader = newDataLoader(keysAsValues());
+
+        dataLoader.load(1).handle((v, t) -> t);
+
+        Collection<CompletableFuture<Integer>> futures = dataLoader.getCacheFutures();
+
+        futures.add(CompletableFuture.completedFuture(2));
+    }
+}

src/test/java/org/dataloader/DataLoaderIfPresentTest.java

@@ -11,7 +11,6 @@
 import static org.hamcrest.Matchers.sameInstance;
 import static org.junit.Assert.assertThat;
 
-
 /**
  * Tests for IfPresent and IfCompleted functionality.
  */

src/test/java/org/dataloader/fixtures/CustomCacheMap.java

@@ -2,6 +2,7 @@
 
 import org.dataloader.CacheMap;
 
+import java.util.Collection;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
@@ -24,6 +25,11 @@ public CompletableFuture<Object> get(String key) {
         return stash.get(key);
     }
 
+    @Override
+    public Collection<CompletableFuture<Object>> getAll() {
+        return stash.values();
+    }
+
     @Override
     public CacheMap<String, Object> set(String key, CompletableFuture<Object> value) {
         stash.put(key, value);