Carmelo Cascone | efc0a92 | 2016-06-14 14:32:33 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2016-present Open Networking Laboratory |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.onosproject.bmv2.demo.app.wcmp; |
| 18 | |
| 19 | import com.google.common.collect.ImmutableList; |
| 20 | import com.google.common.collect.Lists; |
| 21 | import com.google.common.collect.Maps; |
| 22 | import org.onlab.util.ImmutableByteSequence; |
| 23 | import org.onosproject.bmv2.api.runtime.Bmv2Action; |
| 24 | import org.onosproject.bmv2.api.runtime.Bmv2ExtensionTreatment; |
| 25 | import org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils; |
| 26 | import org.onosproject.net.DeviceId; |
| 27 | import org.onosproject.net.PortNumber; |
| 28 | import org.onosproject.net.flow.instructions.ExtensionTreatment; |
| 29 | |
| 30 | import java.util.Collections; |
| 31 | import java.util.List; |
| 32 | import java.util.Map; |
| 33 | |
| 34 | import static com.google.common.base.Preconditions.checkArgument; |
| 35 | import static java.util.stream.Collectors.toList; |
| 36 | import static org.onosproject.bmv2.api.utils.Bmv2TranslatorUtils.fitByteSequence; |
| 37 | import static org.onosproject.bmv2.demo.app.wcmp.WcmpFabricApp.WCMP_CONTEXT; |
| 38 | import static org.onosproject.bmv2.demo.app.wcmp.WcmpInterpreter.*; |
| 39 | |
| 40 | /** |
| 41 | * Builder of WCMP extension treatment. |
| 42 | */ |
| 43 | public final class WcmpGroupTreatmentBuilder { |
| 44 | |
| 45 | private static final double MAX_ERROR = 0.0001; |
| 46 | |
| 47 | private static final Map<DeviceId, Map<Map<PortNumber, Double>, Integer>> DEVICE_GROUP_ID_MAP = Maps.newHashMap(); |
| 48 | |
| 49 | private int groupId; |
| 50 | |
| 51 | /** |
| 52 | * Sets the WCMP group ID. |
| 53 | * |
| 54 | * @param groupId an integer value |
| 55 | * @return this |
| 56 | */ |
| 57 | public WcmpGroupTreatmentBuilder withGroupId(int groupId) { |
| 58 | this.groupId = groupId; |
| 59 | return this; |
| 60 | } |
| 61 | |
| 62 | /** |
| 63 | * Returns a new extension treatment. |
| 64 | * |
| 65 | * @return an extension treatment |
| 66 | */ |
| 67 | public ExtensionTreatment build() { |
| 68 | checkArgument(groupId >= 0, "group id must be a non-zero positive integer"); |
| 69 | ImmutableByteSequence groupIdBs = ImmutableByteSequence.copyFrom(groupId); |
| 70 | final int groupIdBitWidth = WCMP_CONTEXT.configuration().headerType(WCMP_META_T).field(GROUP_ID).bitWidth(); |
| 71 | try { |
| 72 | groupIdBs = fitByteSequence(groupIdBs, groupIdBitWidth); |
| 73 | return new Bmv2ExtensionTreatment( |
| 74 | Bmv2Action.builder() |
| 75 | .withName(WCMP_GROUP) |
| 76 | .addParameter(groupIdBs) |
| 77 | .build()); |
| 78 | } catch (Bmv2TranslatorUtils.ByteSequenceFitException e) { |
| 79 | throw new RuntimeException(e); |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | public static int groupIdOf(DeviceId did, Map<PortNumber, Double> weightedPorts) { |
| 84 | DEVICE_GROUP_ID_MAP.putIfAbsent(did, Maps.newHashMap()); |
| 85 | // Counts the number of unique portNumber sets for each device ID. |
| 86 | // Each distinct set of portNumbers will have a unique ID. |
| 87 | return DEVICE_GROUP_ID_MAP.get(did).computeIfAbsent(weightedPorts, |
| 88 | (pp) -> DEVICE_GROUP_ID_MAP.get(did).size() + 1); |
| 89 | } |
| 90 | |
| 91 | public static List<Integer> toPrefixLengths(List<Double> weigths) throws WcmpGroupException { |
| 92 | |
| 93 | double weightSum = weigths.stream() |
| 94 | .mapToDouble(Double::doubleValue) |
| 95 | .map(WcmpGroupTreatmentBuilder::roundDouble) |
| 96 | .sum(); |
| 97 | |
| 98 | if (Math.abs(weightSum - 1) > MAX_ERROR) { |
| 99 | throw new WcmpGroupException("weights sum is expected to be 1, found was " + weightSum); |
| 100 | } |
| 101 | |
| 102 | final int selectorBitWidth = WCMP_CONTEXT.configuration().headerType(WCMP_META_T).field(SELECTOR).bitWidth(); |
| 103 | final int availableBits = selectorBitWidth - 1; |
| 104 | |
| 105 | List<Long> prefixDiffs = weigths.stream().map(w -> Math.round(w * availableBits)).collect(toList()); |
| 106 | |
| 107 | final long bitSum = prefixDiffs.stream().mapToLong(Long::longValue).sum(); |
| 108 | final long error = availableBits - bitSum; |
| 109 | |
| 110 | if (error != 0) { |
| 111 | // Lazy intuition here is that the error can be absorbed by the longest prefixDiff with the minor impact. |
| 112 | Long maxDiff = Collections.max(prefixDiffs); |
| 113 | int idx = prefixDiffs.indexOf(maxDiff); |
| 114 | prefixDiffs.remove(idx); |
| 115 | prefixDiffs.add(idx, maxDiff + error); |
| 116 | } |
| 117 | List<Integer> prefixLengths = Lists.newArrayList(); |
| 118 | |
| 119 | int prefix = 1; |
| 120 | for (Long p : prefixDiffs) { |
| 121 | prefixLengths.add(prefix); |
| 122 | prefix += p; |
| 123 | } |
| 124 | return ImmutableList.copyOf(prefixLengths); |
| 125 | } |
| 126 | |
| 127 | private static double roundDouble(double n) { |
| 128 | // 5 digits precision. |
| 129 | return (double) Math.round(n * 100000d) / 100000d; |
| 130 | } |
| 131 | |
| 132 | public static class WcmpGroupException extends Exception { |
| 133 | public WcmpGroupException(String s) { |
| 134 | } |
| 135 | } |
| 136 | } |