Java tutorial
/* * Copyright 2016-present Open Networking Laboratory * * 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. */ package org.onosproject.store.resource.impl; import com.google.common.collect.ImmutableList; import com.google.common.collect.Sets; import org.onosproject.net.resource.ContinuousResource; import org.onosproject.net.resource.ContinuousResourceId; import org.onosproject.net.resource.DiscreteResourceId; import org.onosproject.net.resource.ResourceAllocation; import org.onosproject.net.resource.ResourceConsumerId; import org.onosproject.store.service.TransactionContext; import org.onosproject.store.service.TransactionalMap; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.LinkedHashSet; import java.util.Optional; import java.util.Set; import java.util.stream.Collectors; import static com.google.common.base.Preconditions.checkArgument; import static org.onosproject.store.resource.impl.ConsistentResourceStore.SERIALIZER; class TransactionalContinuousResourceSubStore { private final Logger log = LoggerFactory.getLogger(getClass()); private final TransactionalMap<DiscreteResourceId, Set<ContinuousResource>> childMap; private final TransactionalMap<ContinuousResourceId, ContinuousResourceAllocation> consumers; TransactionalContinuousResourceSubStore(TransactionContext tx) { this.childMap = tx.getTransactionalMap(MapNames.CONTINUOUS_CHILD_MAP, SERIALIZER); this.consumers = tx.getTransactionalMap(MapNames.CONTINUOUS_CONSUMER_MAP, SERIALIZER); } // iterate over the values in the set: O(n) operation Optional<ContinuousResource> lookup(ContinuousResourceId id) { // continuous resource always has its parent checkArgument(id.parent().isPresent()); Set<ContinuousResource> values = childMap.get(id.parent().get()); if (values == null) { return Optional.empty(); } return values.stream().filter(x -> x.id().equals(id)).findFirst(); } boolean register(DiscreteResourceId parent, Set<ContinuousResource> resources) { // short-circuit: receiving empty resource is regarded as success if (resources.isEmpty()) { return true; } Set<ContinuousResource> oldValues = childMap.putIfAbsent(parent, resources); if (oldValues == null) { return true; } Set<ContinuousResource> addedValues = Sets.difference(resources, oldValues); // no new value, then no-op if (addedValues.isEmpty()) { // don't write to map because all values are already stored return true; } Set<ContinuousResourceId> addedIds = addedValues.stream().map(ContinuousResource::id) .collect(Collectors.toSet()); // if the value is not found but the same ID is found // (this happens only when being continuous resource) if (oldValues.stream().anyMatch(x -> addedIds.contains(x.id()))) { // no-op, but indicating failure (reject the request) return false; } Set<ContinuousResource> newValues = new LinkedHashSet<>(oldValues); newValues.addAll(addedValues); return childMap.replace(parent, oldValues, newValues); } boolean unregister(DiscreteResourceId parent, Set<ContinuousResource> resources) { // short-circuit: receiving empty resource is regarded as success if (resources.isEmpty()) { return true; } // even if one of the resources is allocated to a consumer, // all unregistrations are regarded as failure boolean allocated = resources.stream().anyMatch(x -> isAllocated(x.id())); if (allocated) { log.warn("Failed to unregister {}: allocation exists", parent); return false; } Set<ContinuousResource> oldValues = childMap.putIfAbsent(parent, new LinkedHashSet<>()); if (oldValues == null) { log.trace("No-Op removing values. key {} did not exist", parent); return true; } if (resources.stream().allMatch(x -> !oldValues.contains(x))) { // don't write map because none of the values are stored log.trace("No-Op removing values. key {} did not contain {}", parent, resources); return true; } LinkedHashSet<ContinuousResource> newValues = new LinkedHashSet<>(oldValues); newValues.removeAll(resources); return childMap.replace(parent, oldValues, newValues); } private boolean isAllocated(ContinuousResourceId id) { ContinuousResourceAllocation allocations = consumers.get(id); return allocations != null && !allocations.allocations().isEmpty(); } boolean allocate(ResourceConsumerId consumerId, ContinuousResource request) { // if the resource is not registered, then abort Optional<ContinuousResource> lookedUp = lookup(request.id()); if (!lookedUp.isPresent()) { return false; } // Down cast: this must be safe as ContinuousResource is associated with ContinuousResourceId ContinuousResource original = lookedUp.get(); ContinuousResourceAllocation allocations = consumers.get(request.id()); if (!Optional.ofNullable(allocations).orElse(ContinuousResourceAllocation.empty(original)) .hasEnoughResource(request)) { return false; } return appendValue(original, new ResourceAllocation(request, consumerId)); } // Appends the specified ResourceAllocation to the existing values stored in the map // computational complexity: O(n) where n is the number of the elements in the associated allocation private boolean appendValue(ContinuousResource original, ResourceAllocation value) { ContinuousResourceAllocation oldValue = consumers.putIfAbsent(original.id(), new ContinuousResourceAllocation(original, ImmutableList.of(value))); if (oldValue == null) { return true; } ContinuousResourceAllocation newValue = oldValue.allocate(value); return consumers.replace(original.id(), oldValue, newValue); } boolean release(ContinuousResource resource, ResourceConsumerId consumerId) { ContinuousResourceAllocation oldAllocation = consumers.get(resource.id()); ContinuousResourceAllocation newAllocation = oldAllocation.release(resource, consumerId); return consumers.replace(resource.id(), oldAllocation, newAllocation); } }