*/
package org.opendaylight.yangtools.util;
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Verify;
+import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
+import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMap.Builder;
+import com.google.common.collect.ImmutableSet;
+import java.lang.reflect.Array;
import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
import java.util.Map;
+import java.util.Set;
final class OffsetMapCache {
- private static final LoadingCache<Collection<?>, Map<Object, Integer>> CACHE =
- CacheBuilder.newBuilder().weakValues().build(new CacheLoader<Collection<?>, Map<Object, Integer>>() {
+ /*
+ * Cache for offsets where order matters. The key is a List, which defines the iteration order. Since we want
+ * to retain this order, it is okay to use a simple LoadingCache.
+ */
+ private static final LoadingCache<List<?>, Map<?, Integer>> ORDERED_CACHE =
+ CacheBuilder.newBuilder().weakValues().build(new CacheLoader<List<?>, Map<?, Integer>>() {
@Override
- public Map<Object, Integer> load(final Collection<?> key) {
- final Builder<Object, Integer> b = ImmutableMap.builder();
- int i = 0;
-
- for (Object arg : key) {
- b.put(arg, i++);
- }
-
- return b.build();
+ public Map<?, Integer> load(final List<?> key) {
+ return createMap(key);
}
});
+ /*
+ * Cache for offsets where order does not mapper. The key is a Set of elements. We use manual two-stage loading
+ * because of the nature of the objects we store as values, which is ImmutableMaps. An ImmutableMap, when queried
+ * for keys (as is done in ImmutableOffsetMap.keySet()), will instantiate an ImmutableSet to hold these keys. It
+ * would be wasteful to use one Set for lookup only to have the map have an exact copy.
+ *
+ * We perform the first look up using a Set (which may come from the user, for example via
+ * ImmutableOffsetMap.unorderedCopyOf()), hence potentially saving a copy operation. If we fail to find an entry,
+ * we construct the map and put it conditionally with Map.keySet() as the key. This will detect concurrent loading
+ * and also lead to the cache and the map sharing the same Set.
+ */
+ private static final Cache<Set<?>, Map<?, Integer>> UNORDERED_CACHE =
+ CacheBuilder.newBuilder().weakValues().build();
private OffsetMapCache() {
throw new UnsupportedOperationException();
}
+ @VisibleForTesting
+ static void invalidateCache() {
+ ORDERED_CACHE.invalidateAll();
+ UNORDERED_CACHE.invalidateAll();
+ }
+
+ @SuppressWarnings("unchecked")
+ static <T> Map<T, Integer> orderedOffsets(final Collection<T> args) {
+ if (args.size() == 1) {
+ return unorderedOffsets(args);
+ }
+
+ return (Map<T, Integer>) ORDERED_CACHE.getUnchecked(ImmutableList.copyOf(args));
+ }
+
+ static <T> Map<T, Integer> unorderedOffsets(final Collection<T> args) {
+ return unorderedOffsets(args instanceof Set ? (Set<T>)args : ImmutableSet.copyOf(args));
+ }
+
+ static <K, V> V[] adjustedArray(final Map<K, Integer> offsets, final List<K> keys, final V[] array) {
+ Verify.verify(offsets.size() == keys.size(), "Offsets %s do not match keys %s", offsets, keys);
+
+ // This relies on the fact that offsets has an ascending iterator
+ final Iterator<K> oi = offsets.keySet().iterator();
+ final Iterator<K> ki = keys.iterator();
+
+ while (oi.hasNext()) {
+ final K o = oi.next();
+ final K k = ki.next();
+ if (!k.equals(o)) {
+ return adjustArray(offsets, keys, array);
+ }
+ }
+
+ return array;
+ }
+
+ private static <T> Map<T, Integer> createMap(final Collection<T> keys) {
+ final Builder<T, Integer> b = ImmutableMap.builder();
+ int i = 0;
+
+ for (T arg : keys) {
+ b.put(arg, i++);
+ }
+
+ return b.build();
+ }
+
@SuppressWarnings("unchecked")
- static <T> Map<T, Integer> offsetsFor(final Collection<T> args) {
- return (Map<T, Integer>) CACHE.getUnchecked(args);
+ private static <T> Map<T, Integer> unorderedOffsets(final Set<T> args) {
+ final Map<T, Integer> existing = (Map<T, Integer>) UNORDERED_CACHE.getIfPresent(args);
+ if (existing != null) {
+ return existing;
+ }
+
+ final Map<T, Integer> newMap = createMap(args);
+ final Map<?, Integer> raced = UNORDERED_CACHE.asMap().putIfAbsent(newMap.keySet(), newMap);
+ return raced == null ? newMap : (Map<T, Integer>)raced;
+ }
+
+ private static <K, V> V[] adjustArray(final Map<K, Integer> offsets, final List<K> keys, final V[] array) {
+ @SuppressWarnings("unchecked")
+ final V[] ret = (V[]) Array.newInstance(array.getClass().getComponentType(), array.length);
+
+ int i = 0;
+ for (final K k : keys) {
+ final Integer o = Verify.verifyNotNull(offsets.get(k), "Key %s not present in offsets %s", k, offsets);
+ ret[o] = array[i++];
+ }
+
+ return ret;
}
}
Code Review / yangtools.git / blobdiff