X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=common%2Futil%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fyangtools%2Futil%2FOffsetMapCache.java;h=b18c218f2185e1920928e0a35a905b79da9e62ea;hb=6ba98a2fab390cafe7a98e466189ea8df09cdeb9;hp=0863e286f6c37be1cc4dc9d66261a9623a38f3dc;hpb=b5baf0c5df8e298a4c50197038c2dd2a6d71abb1;p=yangtools.git

diff --git a/common/util/src/main/java/org/opendaylight/yangtools/util/OffsetMapCache.java b/common/util/src/main/java/org/opendaylight/yangtools/util/OffsetMapCache.java
index 0863e286f6..b18c218f21 100644
--- a/common/util/src/main/java/org/opendaylight/yangtools/util/OffsetMapCache.java
+++ b/common/util/src/main/java/org/opendaylight/yangtools/util/OffsetMapCache.java
@@ -7,36 +7,123 @@
  */
 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;
     }
 }