From 6bf5132b68881aadb4f52da98f723e196dc7c4d3 Mon Sep 17 00:00:00 2001
From: Jeffrey Phillips Freeman <jeffrey.freeman@syncleus.com>
Date: Thu, 29 Dec 2016 07:43:31 -0500
Subject: [PATCH] Added a map-reduce example.
---
src/main/java/com/aparapi/examples/All.java | 4 +
.../com/aparapi/examples/mapreduce/Main.java | 87 +++++++++++++++++++
2 files changed, 91 insertions(+)
create mode 100644 src/main/java/com/aparapi/examples/mapreduce/Main.java
diff --git a/src/main/java/com/aparapi/examples/All.java b/src/main/java/com/aparapi/examples/All.java
index 035ca41c..b27b601a 100644
--- a/src/main/java/com/aparapi/examples/All.java
+++ b/src/main/java/com/aparapi/examples/All.java
@@ -66,6 +66,7 @@ public class All {
System.out.println(" 32) NBody - Local");
System.out.println(" 33) NBody - Sequential");
System.out.println(" 34) OOPN Body");
+ System.out.println(" 35) Map-reduce");
System.out.println();
Scanner in = new Scanner(System.in);
@@ -198,6 +199,9 @@ public class All {
case "34":
com.aparapi.examples.oopnbody.Main.main(args);
break;
+ case "35":
+ com.aparapi.examples.mapreduce.Main.main(args);
+ break;
default:
System.out.println("Invalid selection.");
}
diff --git a/src/main/java/com/aparapi/examples/mapreduce/Main.java b/src/main/java/com/aparapi/examples/mapreduce/Main.java
new file mode 100644
index 00000000..5b8034d7
--- /dev/null
+++ b/src/main/java/com/aparapi/examples/mapreduce/Main.java
@@ -0,0 +1,87 @@
+/**
+ * This product currently only contains code developed by authors
+ * of specific components, as identified by the source code files.
+ *
+ * Since product implements StAX API, it has dependencies to StAX API
+ * classes.
+ *
+ * For additional credits (generally to people who reported problems)
+ * see CREDITS file.
+ */
+
+package com.aparapi.examples.mapreduce;
+
+import com.aparapi.Kernel;
+import com.aparapi.Range;
+
+import java.util.Arrays;
+
+public class Main {
+ public static void main(String[] args) {
+ int size = 1048576;
+ final int count = 3;
+ final int[] V = new int[size];
+
+ //lets fill in V randomly...
+ for (int i = 0; i < size; i++) {
+ //random number either 0, 1, or 2
+ V[i] = (int) (Math.random() * 3);
+ }
+
+ //this will hold our values between the phases.
+ int[][] totals = new int[count][size];
+
+ ///////////////
+ // MAP PHASE //
+ ///////////////
+ final int[][] kernelTotals = totals;
+ Kernel mapKernel = new Kernel() {
+ @Override
+ public void run() {
+ int gid = getGlobalId();
+ int value = V[gid];
+ for(int index = 0; index < count; index++) {
+ if (value == index)
+ kernelTotals[index][gid] = 1;
+ }
+ }
+ };
+ mapKernel.execute(Range.create(size));
+ mapKernel.dispose();
+ totals = kernelTotals;
+
+ //////////////////
+ // REDUCE PHASE //
+ //////////////////
+ while (size > 1) {
+ int nextSize = size / 2;
+ final int[][] currentTotals = totals;
+ final int[][] nextTotals = new int[count][nextSize];
+ Kernel reduceKernel = new Kernel() {
+ @Override
+ public void run() {
+ int gid = getGlobalId();
+ for(int index = 0; index < count; index++) {
+ nextTotals[index][gid] = currentTotals[index][gid * 2] + currentTotals[index][gid * 2 + 1];
+ }
+ }
+ };
+ reduceKernel.execute(Range.create(nextSize));
+ reduceKernel.dispose();
+
+ totals = nextTotals;
+ size = nextSize;
+ }
+ assert size == 1;
+
+ /////////////////////////////
+ // Done, just print it out //
+ /////////////////////////////
+ int[] results = new int[3];
+ results[0] = totals[0][0];
+ results[1] = totals[1][0];
+ results[2] = totals[2][0];
+
+ System.out.println(Arrays.toString(results));
+ }
+}
--
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