From 8780d5d47af33fc00bb5159c810c3e68827cd43a Mon Sep 17 00:00:00 2001
From: Florian Steurer <florian.steurer95@gmail.com>
Date: Wed, 20 Apr 2016 12:15:04 +0200
Subject: [PATCH] option for parallelization

---
 .../typeinference/unify/TypeUnify.java        | 56 ++++++++++++++-----
 1 file changed, 42 insertions(+), 14 deletions(-)

diff --git a/src/de/dhbwstuttgart/typeinference/unify/TypeUnify.java b/src/de/dhbwstuttgart/typeinference/unify/TypeUnify.java
index 60e775369..2e0d70fd1 100644
--- a/src/de/dhbwstuttgart/typeinference/unify/TypeUnify.java
+++ b/src/de/dhbwstuttgart/typeinference/unify/TypeUnify.java
@@ -3,6 +3,7 @@ package de.dhbwstuttgart.typeinference.unify;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.LinkedList;
@@ -10,6 +11,7 @@ import java.util.List;
 import java.util.Map.Entry;
 import java.util.Optional;
 import java.util.Set;
+import java.util.function.Function;
 import java.util.stream.Collectors;
 
 import de.dhbwstuttgart.typeinference.unify.interfaces.IFiniteClosure;
@@ -47,6 +49,8 @@ public class TypeUnify {
 	 */
 	protected IRuleSet rules = new RuleSet();
 	
+	protected boolean parallel = true;
+	
 	/**
 	 * Computes all principal type unifiers for a set of constraints.
 	 * @param eq The set of constraints
@@ -110,7 +114,7 @@ public class TypeUnify {
 		
 		// Sub cartesian products of the second level (pattern matched) sets
 		// "the big (x)"
-		// TODO Optimierungsmöglichkeit: Parallelisierung der Schleife möglich
+		// TODO Optimierungsmöglichkeit: Parallelisierung der Schleife möglich (scheint sich nicht zu lohnen)
 		for(Set<Set<Set<UnifyPair>>> secondLevelSet : secondLevelSets) {
 			List<Set<Set<UnifyPair>>> secondLevelSetList = new ArrayList<>(secondLevelSet);
 			Set<List<Set<UnifyPair>>> cartResult = setOps.cartesianProduct(secondLevelSetList);
@@ -133,7 +137,7 @@ public class TypeUnify {
 		//System.out.println(result);
 
 		// Flatten the cartesian product
-		// TODO parallelisierung möglich
+		// TODO parallelisierung möglich (scheint sich nicht zu lohnen)
 		Set<Set<UnifyPair>> eqPrimeSetFlat = new HashSet<>();
 		for(Set<Set<UnifyPair>> setToFlatten : eqPrimeSet) {
 			Set<UnifyPair> buffer = new HashSet<>();
@@ -148,15 +152,33 @@ public class TypeUnify {
 		Set<Set<UnifyPair>> restartSet = new HashSet<>();
 		Set<Set<UnifyPair>> eqPrimePrimeSet = new HashSet<>();
 		
-		for(Set<UnifyPair> eqPrime : eqPrimeSetFlat) {
-			Optional<Set<UnifyPair>> eqPrimePrime = rules.subst(eqPrime);
+		
+		if(parallel) {
+	        Set<Set<UnifyPair>> restartSetSync = Collections.synchronizedSet(restartSet);
+	        Set<Set<UnifyPair>> eqPrimePrimeSetSync = Collections.synchronizedSet(eqPrimePrimeSet);
 			
-			if (eqPrime.equals(eq))
-				eqPrimePrimeSet.add(eqPrime);
-			else if(eqPrimePrime.isPresent())
-				restartSet.add(eqPrimePrime.get());
-			else
-				restartSet.add(eqPrime);
+	        eqPrimeSetFlat.parallelStream().forEach(eqPrime -> {
+				Optional<Set<UnifyPair>> eqPrimePrime = rules.subst(eqPrime);
+				
+				if (eqPrime.equals(eq))
+					eqPrimePrimeSetSync.add(eqPrime);
+				else if(eqPrimePrime.isPresent())
+					restartSetSync.add(eqPrimePrime.get());
+				else
+					restartSetSync.add(eqPrime);
+			});
+		}
+		else {
+			for(Set<UnifyPair> eqPrime : eqPrimeSetFlat) {
+				Optional<Set<UnifyPair>> eqPrimePrime = rules.subst(eqPrime);
+				
+				if (eqPrime.equals(eq))
+					eqPrimePrimeSet.add(eqPrime);
+				else if(eqPrimePrime.isPresent())
+					restartSet.add(eqPrimePrime.get());
+				else
+					restartSet.add(eqPrime);
+			}
 		}
 
 		/*
@@ -164,10 +186,16 @@ public class TypeUnify {
 		 * 		  b) Build the union over everything
 		 */
 		// TODO parallelisierung möglich (lohnt sich vermutlich)
-		for(Set<UnifyPair> eqss : restartSet)
-			eqPrimePrimeSet.addAll(this.unify(eqss, fc));
-		/*restartSet.parallelStream().forEach( 
-				x -> eqPrimePrimeSet.addAll(unify(x, fc)));*/
+		
+		if(parallel) {
+	        Set<Set<UnifyPair>> eqPrimePrimeSetSync = Collections.synchronizedSet(eqPrimePrimeSet);
+			restartSet.parallelStream().forEach( x -> eqPrimePrimeSetSync.addAll(unify(x, fc)));
+		} 
+		else {
+			for(Set<UnifyPair> eqss : restartSet)
+				eqPrimePrimeSet.addAll(this.unify(eqss, fc));
+		}
+
 		 /*
 		  * Step 7: Filter empty sets;
 		  */