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diff --git a/resource-assignment/provider/src/main/java/org/openecomp/sdnc/rm/util/LimitUtil.java b/resource-assignment/provider/src/main/java/org/openecomp/sdnc/rm/util/LimitUtil.java
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+/*-
+ * ============LICENSE_START=======================================================
+ * openECOMP : SDN-C
+ * ================================================================================
+ * Copyright (C) 2017 AT&T Intellectual Property. All rights
+ *             reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.openecomp.sdnc.rm.util;
+
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import org.openecomp.sdnc.rm.data.AllocationItem;
+import org.openecomp.sdnc.rm.data.LimitAllocationItem;
+import org.openecomp.sdnc.rm.data.LimitAllocationRequest;
+import org.openecomp.sdnc.rm.data.LimitResource;
+import org.openecomp.sdnc.rm.data.ResourceKey;
+import org.openecomp.sdnc.rm.data.ResourceType;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class LimitUtil {
+
+	private static final Logger log = LoggerFactory.getLogger(LimitUtil.class);
+
+	public static boolean checkLimit(LimitResource l, LimitAllocationRequest req) {
+		if (req.checkCount <= 0)
+			return true;
+
+		long checkCount = req.checkCount;
+		long currentUsage = 0;
+		if (req.resourceSetId != null) {
+			LimitAllocationItem lai = (LimitAllocationItem) ResourceUtil.getAllocationItem(l, req.resourceSetId);
+			if (lai != null)
+				currentUsage = lai.used;
+		}
+		if (!req.replace)
+			checkCount += currentUsage;
+
+		long used = calculateLimitUsage(l, 0, null, null);
+		long wouldUse = calculateLimitUsage(l, checkCount, req.resourceUnionId, req.resourceShareGroupList);
+
+		// If usage is not increasing by this request, only check the limit if
+		// strictCheck is true.
+		if (wouldUse <= used && !req.strict)
+			return true;
+
+		return wouldUse <= req.checkLimit;
+	}
+
+	private static long calculateLimitUsage(
+	        LimitResource l,
+	        long checkCount,
+	        String resourceUnionId,
+	        Set<String> resourceShareGroupList) {
+		if ((l.allocationItems == null || l.allocationItems.isEmpty()) &&
+		        (resourceUnionId == null || resourceUnionId.length() == 0))
+			return 0;
+
+		long t1 = System.currentTimeMillis();
+		boolean logit = false;
+		String rn = "Resource: " + l.resourceKey.resourceName + " - " + l.resourceKey.assetId;
+
+		// In order to best utilize the resource, we need to take not the sum of all allocation items, but
+		// instead the maximum usage that could happen at any moment of time (given not all allocation items are active
+		// at the same time), also taking into account possible resource sharing.
+		// Thus we need to find all combinations of allocation items that can be active at the same time (allocation
+		// items with the same first union cannot be active at the same time), compute the usage for each (again,
+		// taking into account resource sharing), and take the maximum.
+		//
+		// Example:
+		// Let's have the following allocation items:
+		// ai1: sdid1, vrf1 - usage 5
+		// ai2: sdid2, vrf1 - usage 10
+		// ai3: sdid3, vrf2 - usage 15
+		// ai4: sdid1, vrf3 - usage 20
+		// ai5: sdid3, vrf1 - usage 25
+		// The following combinations of active allocation items are possible:
+		// 1) ai1, ai2, ai3
+		// 2) ai1, ai2, ai5
+		// 3) ai2, ai3, ai4
+		// 4) ai2, ai3, ai5
+		// Here is how we calculate the usage for combination 1:
+		// ai1 and ai2 contain the same resource union vrf1, so they share the resource - we take the max of usage,
+		// so we have:
+		// max(5, 10) + 15 = 25
+		// Similarly, we calculate the usage of the other combinations:
+		// 2) max(5, 10, 25) = 25
+		// 3) 10 + 15 + 20 = 45
+		// 4) max(10, 25) + 15 = 40
+		// So, the result in this case is:
+		// max(25, 25, 45, 40) = 45
+		//
+		// We might have a problem with this approach, if we have a lot of combinations. Assuming we have at most 2
+		// allocation items with the same resource union (sdid), the number of combinations would be
+		// 2 ^ n
+		// where n is the number of allocation items that have the same resource union (sdid). That would be
+		// the number of change orders currently in progress.
+		//
+		// Here is one optimization that we can do:
+		// If we have allocation items that have all resource unions the same, we don't need to generate combinations
+		// with each of them, we can just take the one of them with the maximum usage, as it is clear that the others
+		// will not lead to a bigger usage.
+		// For example, if we had the following allocation items:
+		// ai1: sdid1, vrf1 - usage 10
+		// ai2: sdid1, vrf1 - usage 20
+		// We only need to take the combinations with ai2, as they will always lead to bigger usage than the remaining
+		// combinations with ai1.
+
+		// First, group the allocation items by the first resource union, using the LimitUsage structure
+		int regularChangeCount = 0;
+		Map<String/* resourceUnionId */, List<LimitUsage>> limitUsageMap = new HashMap<String, List<LimitUsage>>();
+		if (l.allocationItems != null)
+			for (AllocationItem ai : l.allocationItems) {
+				LimitAllocationItem lai = (LimitAllocationItem) ai;
+				boolean regularChange =
+				        addLimitUsage(limitUsageMap, lai.resourceUnionId, lai.resourceShareGroupList, lai.used);
+				if (regularChange)
+					regularChangeCount++;
+			}
+		if (checkCount > 0 && resourceUnionId != null) {
+			boolean regularChange = addLimitUsage(limitUsageMap, resourceUnionId, resourceShareGroupList, checkCount);
+			if (regularChange)
+				regularChangeCount++;
+		}
+
+		// Generate all the combinations, containing one LimitUsage object for each firstResourceUnion
+		int significantChangeCount = 0;
+		List<List<LimitUsage>> allCombinations = new ArrayList<List<LimitUsage>>();
+		for (String firstResourceUnion : limitUsageMap.keySet()) {
+			List<LimitUsage> limitUsageList = limitUsageMap.get(firstResourceUnion);
+			if (limitUsageList.size() > 1)
+				significantChangeCount++;
+			if (allCombinations.isEmpty()) {
+				for (LimitUsage limitUsage : limitUsageList) {
+					List<LimitUsage> newCombination = new ArrayList<LimitUsage>();
+					newCombination.add(limitUsage);
+					allCombinations.add(newCombination);
+				}
+			} else {
+				if (limitUsageList.size() == 1) {
+					// No new combinations are generated - just add this one to all combinations we have until now
+					for (List<LimitUsage> combination : allCombinations)
+						combination.add(limitUsageList.get(0));
+				} else {
+					// We have to duplicate each of the current combinations for each element of limitUsageList
+					List<List<LimitUsage>> newAllCombinations = new ArrayList<List<LimitUsage>>();
+					for (List<LimitUsage> combination : allCombinations)
+						for (LimitUsage limitUsage : limitUsageList) {
+							List<LimitUsage> newCombination = new ArrayList<LimitUsage>(combination);
+							newCombination.add(limitUsage);
+							newAllCombinations.add(newCombination);
+						}
+					allCombinations = newAllCombinations;
+				}
+			}
+		}
+
+		// Now, go through all combinations and calculate its usage, get the maximum
+		long maxUsage = 0;
+		for (List<LimitUsage> combination : allCombinations) {
+			long usage = calculateUsage(combination);
+			if (usage > maxUsage)
+				maxUsage = usage;
+		}
+
+		long t2 = System.currentTimeMillis();
+		if (logit) {
+			log.debug(rn + ": Calculating usage completed:");
+			log.debug(rn + ":     Regular changes: " + regularChangeCount);
+			log.debug(rn + ":     Significant changes: " + significantChangeCount);
+			log.debug(rn + ":     Combinations: " + allCombinations.size());
+			log.debug(rn + ":     Usage: " + maxUsage);
+			log.debug(rn + ":     Time: " + (t2 - t1));
+		}
+
+		return maxUsage;
+	}
+
+	private static boolean addLimitUsage(
+	        Map<String/* resourceUnionId */, List<LimitUsage>> limitUsageMap,
+	        String resourceUnionId,
+	        Set<String> resourceShareGroupList,
+	        long used) {
+		List<LimitUsage> limitUsageList = limitUsageMap.get(resourceUnionId);
+		if (limitUsageList == null) {
+			limitUsageList = new ArrayList<LimitUsage>();
+			limitUsageMap.put(resourceUnionId, limitUsageList);
+		}
+		// See if we already have the same shareResourceUnionSet in the list. In such case just update the usage
+		// to the bigger value.
+		LimitUsage limitUsage = null;
+		for (LimitUsage limitUsage1 : limitUsageList) {
+			if ((limitUsage1.resourceShareGroupList == null || limitUsage1.resourceShareGroupList.isEmpty()) &&
+			        (resourceShareGroupList == null || resourceShareGroupList.isEmpty())) {
+				limitUsage = limitUsage1;
+				break;
+			}
+			if (limitUsage1.resourceShareGroupList != null &&
+			        limitUsage1.resourceShareGroupList.equals(resourceShareGroupList)) {
+				limitUsage = limitUsage1;
+				break;
+			}
+		}
+		if (limitUsage != null) {
+			if (limitUsage.usage < used)
+				limitUsage.usage = used;
+			return true;
+		}
+
+		limitUsage = new LimitUsage();
+		limitUsage.resourceUnion = resourceUnionId;
+		limitUsage.resourceShareGroupList = resourceShareGroupList;
+		limitUsage.usage = used;
+		limitUsageList.add(limitUsage);
+		return false;
+	}
+
+	private static class LimitUsage {
+
+		@SuppressWarnings("unused")
+		public String resourceUnion;
+		public Set<String> resourceShareGroupList;
+		public long usage;
+	}
+
+	private static boolean hasCommonSharedResource(LimitUsage limitUsage1, LimitUsage limitUsage2) {
+		if (limitUsage1.resourceShareGroupList == null || limitUsage1.resourceShareGroupList.isEmpty())
+			return false;
+		if (limitUsage2.resourceShareGroupList == null || limitUsage2.resourceShareGroupList.isEmpty())
+			return false;
+
+		for (String resourceUnion : limitUsage1.resourceShareGroupList)
+			if (limitUsage2.resourceShareGroupList.contains(resourceUnion))
+				return true;
+
+		return false;
+	}
+
+	private static long calculateUsage(List<LimitUsage> combination) {
+		// All LimitUsage objects that have a common value in their sharedResourceUnionSet reuse the resource, so
+		// split the combination in sets that have common value. Then the usage of each set will be the maximum of
+		// the usages of the LimitUsage objects in the set. The usage of the combination will be the sum of the usages
+		// of all sets.
+		List<List<LimitUsage>> sharedSets = new ArrayList<List<LimitUsage>>();
+		for (LimitUsage limitUsage : combination) {
+			// See if we can put limitUsage in any of the existing sets - is it has a common resource union with
+			// any of the LimitUsage objects in a set.
+			boolean found = false;
+			for (List<LimitUsage> sharedSet : sharedSets) {
+				for (LimitUsage limitUsage1 : sharedSet) {
+					if (hasCommonSharedResource(limitUsage, limitUsage1)) {
+						found = true;
+						break;
+					}
+				}
+				if (found) {
+					sharedSet.add(limitUsage);
+					break;
+				}
+			}
+			if (!found) {
+				// Start a new set
+				List<LimitUsage> newSharedSet = new ArrayList<LimitUsage>();
+				newSharedSet.add(limitUsage);
+				sharedSets.add(newSharedSet);
+			}
+		}
+
+		long sum = 0;
+		for (List<LimitUsage> sharedSet : sharedSets) {
+			float max = 0;
+			for (LimitUsage limitUsage : sharedSet)
+				if (max < limitUsage.usage)
+					max = limitUsage.usage;
+			sum += max;
+		}
+
+		return sum;
+	}
+
+	public static long allocateLimit(LimitResource l, LimitAllocationRequest req, String applicationId) {
+		if (req.allocateCount <= 0)
+			return 0;
+		long uu = l.used;
+
+		LimitAllocationItem lai = (LimitAllocationItem) ResourceUtil.getAllocationItem(l, req.resourceSetId);
+		if (lai == null) {
+			lai = new LimitAllocationItem();
+			lai.resourceType = ResourceType.Limit;
+			lai.resourceKey = new ResourceKey();
+			lai.resourceKey.assetId = req.assetId;
+			lai.resourceKey.resourceName = req.resourceName;
+			lai.applicationId = applicationId;
+			lai.resourceSetId = req.resourceSetId;
+			lai.resourceUnionId = req.resourceUnionId;
+			lai.resourceShareGroupList = req.resourceShareGroupList;
+			lai.used = req.allocateCount;
+
+			if (l.allocationItems == null)
+				l.allocationItems = new ArrayList<AllocationItem>();
+			l.allocationItems.add(lai);
+		} else
+			lai.used = req.replace ? req.allocateCount : lai.used + req.allocateCount;
+
+		lai.allocationTime = new Date();
+
+		recalculate(l);
+
+		return l.used - uu;
+	}
+
+	public static void recalculate(LimitResource l) {
+		l.used = calculateLimitUsage(l, 0, null, null);
+	}
+}