2 * Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.protocol.bgp.mode.impl.add;
10 import static com.google.common.base.Preconditions.checkArgument;
12 import com.google.common.cache.CacheBuilder;
13 import com.google.common.cache.CacheLoader;
14 import com.google.common.cache.LoadingCache;
15 import com.google.common.collect.ImmutableSet;
16 import com.google.common.collect.ImmutableSet.Builder;
17 import java.lang.reflect.Array;
18 import java.util.Arrays;
19 import java.util.Collections;
20 import java.util.Comparator;
22 import javax.annotation.Nonnull;
23 import org.slf4j.Logger;
24 import org.slf4j.LoggerFactory;
27 * A map of Router identifier to an offset. Used to maintain a simple
28 * offset-based lookup across multiple RouteEntry objects,
29 * which share either contributors or consumers.
30 * We also provide utility reformat methods, which provide access to
31 * array members and array management features.
33 final class OffsetMap {
34 private static final Logger LOG = LoggerFactory.getLogger(OffsetMap.class);
35 private static final String NEGATIVEOFFSET = "Invalid negative offset %s";
36 private static final String INVALIDOFFSET = "Invalid offset %s for %s router IDs";
37 private static final LoadingCache<Set<RouteKey>, OffsetMap> OFFSETMAPS = CacheBuilder.newBuilder().weakValues()
38 .build(new CacheLoader<Set<RouteKey>, OffsetMap>() {
40 public OffsetMap load(@Nonnull final Set<RouteKey> key) {
41 return new OffsetMap(key);
44 private static final Comparator<RouteKey> COMPARATOR = RouteKey::compareTo;
45 private static final RouteKey[] EMPTY_KEYS = new RouteKey[0];
46 static final OffsetMap EMPTY = new OffsetMap(Collections.emptySet());
48 private final RouteKey[] routeKeys;
50 private OffsetMap(final Set<RouteKey> routerIds) {
51 final RouteKey[] array = routerIds.toArray(EMPTY_KEYS);
52 Arrays.sort(array, COMPARATOR);
53 this.routeKeys = array;
56 int offsetOf(final RouteKey key) {
57 return Arrays.binarySearch(this.routeKeys, key, COMPARATOR);
61 return this.routeKeys.length;
64 OffsetMap with(final RouteKey key) {
65 // TODO: we could make this faster if we had an array-backed Set and requiring
66 // the caller to give us the result of offsetOf() -- as that indicates
67 // where to insert the new routerId while maintaining the sorted nature
69 final Builder<RouteKey> builder = ImmutableSet.builder();
70 builder.add(this.routeKeys);
73 return OFFSETMAPS.getUnchecked(builder.build());
76 OffsetMap without(final RouteKey key) {
77 final Builder<RouteKey> builder = ImmutableSet.builder();
78 final int index = indexOfRouterId(key);
80 LOG.trace("Router key {} not found", key);
82 builder.add(removeValue(this.routeKeys, index, EMPTY_KEYS));
84 return OFFSETMAPS.getUnchecked(builder.build());
87 private int indexOfRouterId(final RouteKey key) {
88 for (int i = 0; i < this.routeKeys.length; i++) {
89 if (key.equals(this.routeKeys[i])) {
96 RouteKey getKey(final int offset) {
97 return routeKeys[offset];
100 <T> T getValue(final T[] array, final int offset) {
101 checkArgument(offset >= 0, NEGATIVEOFFSET, offset);
102 checkArgument(offset < this.routeKeys.length, INVALIDOFFSET, offset, this.routeKeys.length);
103 return array[offset];
106 <T> void setValue(final T[] array, final int offset, final T value) {
107 checkArgument(offset >= 0, NEGATIVEOFFSET, offset);
108 checkArgument(offset < this.routeKeys.length, INVALIDOFFSET, offset, this.routeKeys.length);
109 array[offset] = value;
112 <T> T[] expand(final OffsetMap oldOffsets, final T[] oldArray, final int offset) {
113 @SuppressWarnings("unchecked")
114 final T[] ret = (T[]) Array.newInstance(oldArray.getClass().getComponentType(), this.routeKeys.length);
115 final int oldSize = oldOffsets.routeKeys.length;
117 System.arraycopy(oldArray, 0, ret, 0, offset);
118 System.arraycopy(oldArray, offset, ret, offset + 1, oldSize - offset);
123 <T> T[] removeValue(final T[] oldArray, final int offset, final T[] emptyArray) {
124 final int length = oldArray.length;
125 checkArgument(offset >= 0, NEGATIVEOFFSET, offset);
126 checkArgument(offset < this.routeKeys.length, INVALIDOFFSET, offset, length);
128 final int newLength = length - 1;
129 if (newLength == 0) {
130 checkArgument(emptyArray.length == 0);
134 final T[] ret = (T[]) Array.newInstance(oldArray.getClass().getComponentType(), newLength);
135 System.arraycopy(oldArray, 0, ret, 0, offset);
136 if (offset < newLength) {
137 System.arraycopy(oldArray, offset + 1, ret, offset, newLength - offset);
144 return this.size() == 0;