From cb491e82b5ce3dcb7e3c41973a46cb7dcbaa9008 Mon Sep 17 00:00:00 2001
From: "github-classroom[bot]"
 <66690702+github-classroom[bot]@users.noreply.github.com>
Date: Sun, 10 Dec 2023 19:07:21 +0000
Subject: Initial commit

---
 mapreduce/MapReduce.java | 84 ++++++++++++++++++++++++++++++++++++++++++++++++
 mapreduce/Mapper.java    | 22 +++++++++++++
 mapreduce/Reducer.java   | 26 +++++++++++++++
 3 files changed, 132 insertions(+)
 create mode 100644 mapreduce/MapReduce.java
 create mode 100644 mapreduce/Mapper.java
 create mode 100644 mapreduce/Reducer.java

(limited to 'mapreduce')

diff --git a/mapreduce/MapReduce.java b/mapreduce/MapReduce.java
new file mode 100644
index 0000000..f993f09
--- /dev/null
+++ b/mapreduce/MapReduce.java
@@ -0,0 +1,84 @@
+package mapreduce;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ForkJoinPool;
+import java.util.function.Supplier;
+
+/**
+ *
+ * @author mph
+ * @param <IN>  input type
+ * @param <K>   key type
+ * @param <V>   value type
+ * @param <OUT> output type
+ */
+public class MapReduce<IN, K, V, OUT>
+    implements Callable<Map<K, OUT>> {
+
+  private List<IN> inputList;
+  private Supplier<Mapper<IN, K, V>> mapperSupplier;
+  private Supplier<Reducer<K, V, OUT>> reducerSupplier;
+  private static ForkJoinPool pool;
+
+  /**
+   *
+   */
+  public MapReduce() {
+    pool = new ForkJoinPool();
+    mapperSupplier = () -> {
+      throw new UnsupportedOperationException("No mapper supplier");
+    };
+    reducerSupplier = () -> {
+      throw new UnsupportedOperationException("No reducer supplier");
+    };
+  }
+
+  @Override
+  public Map<K, OUT> call() {
+    Set<Mapper<IN, K, V>> mappers = new HashSet<>();
+    // TODO: for each element in inputList, create a mapper thread, set its input, and execute it
+    // helpful methods: Supplier.get() ForkJoinPool.execute()
+    
+    Map<K, List<V>> mapResults = new HashMap<>();
+    // TODO: for each mapper thread, join and merge the results
+    // helpful methods: ForkJoinTask.join()
+
+    Map<K, Reducer<K, V, OUT>> reducers = new HashMap<>();
+    // TODO: for each key in the mappers'results, create a reducer thread, set its input, and execute it
+    // helpful methods: Supplier.get() ForkJoinPool.execute()
+
+    Map<K, OUT> result = new HashMap<>();
+    // TODO: for each reducer thread, join and merge the result to the final result
+    // helpful methods: ForkJoinTask.join()
+    
+    throw new UnsupportedOperationException("MapReduce.call() not implemented yet.");
+  }
+
+  /**
+   * @param aMapperSupplier construct mapper thread
+   */
+  public void setMapperSupplier(Supplier<Mapper<IN, K, V>> aMapperSupplier) {
+    mapperSupplier = aMapperSupplier;
+  }
+
+  /**
+   * @param aReducerSupplier construct reducer thread
+   */
+  public void setReducerSupplier(Supplier<Reducer<K, V, OUT>> aReducerSupplier) {
+    reducerSupplier = aReducerSupplier;
+  }
+
+  /**
+   * @param anInput the task's set of inputs
+   */
+  public void setInput(List<IN> anInput) {
+    inputList = anInput;
+  }
+
+}
diff --git a/mapreduce/Mapper.java b/mapreduce/Mapper.java
new file mode 100644
index 0000000..c2da326
--- /dev/null
+++ b/mapreduce/Mapper.java
@@ -0,0 +1,22 @@
+package mapreduce;
+
+import java.util.Map;
+import java.util.concurrent.RecursiveTask;
+
+/**
+ *
+ * @author mph
+ * @param <IN> input type
+ * @param <K>  key type
+ * @param <V>  accumulator type
+ */
+public abstract class Mapper<IN, K, V> extends RecursiveTask<Map<K, V>> {
+  protected IN input;
+
+  /**
+   * @param anInput list of input items
+   */
+  public void setInput(IN anInput) {
+    input = anInput;
+  }
+}
diff --git a/mapreduce/Reducer.java b/mapreduce/Reducer.java
new file mode 100644
index 0000000..982ddfc
--- /dev/null
+++ b/mapreduce/Reducer.java
@@ -0,0 +1,26 @@
+package mapreduce;
+
+import java.util.List;
+import java.util.concurrent.RecursiveTask;
+
+/**
+ *
+ * @author mph
+ * @param <K>   key
+ * @param <V>   valueListumulator
+ * @param <OUT> output value
+ */
+public abstract class Reducer<K, V, OUT> extends RecursiveTask<OUT> {
+
+  protected K key;
+  protected List<V> valueList;
+
+  /**
+   * @param aKey  key for this reducer
+   * @param aList list of values
+   */
+  public void setInput(K aKey, List<V> aList) {
+    key = aKey;
+    valueList = aList;
+  }
+};
-- 
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