Examples with ToLongFunction java.util.function.ToLongFunction used on opensource projects

Example 1 with ToLongFunction

use of java.util.function.ToLongFunction in project lucene-solr by apache.

the class RamUsageTester method measureObjectSize.

/*
   * Non-recursive version of object descend. This consumes more memory than recursive in-depth
   * traversal but prevents stack overflows on long chains of objects
   * or complex graphs (a max. recursion depth on my machine was ~5000 objects linked in a chain
   * so not too much).
   */
private static long measureObjectSize(Object root, Accumulator accumulator) {
    // Objects seen so far.
    final Set<Object> seen = Collections.newSetFromMap(new IdentityHashMap<Object, Boolean>());
    // Class cache with reference Field and precalculated shallow size. 
    final IdentityHashMap<Class<?>, ClassCache> classCache = new IdentityHashMap<>();
    // Stack of objects pending traversal. Recursion caused stack overflows. 
    final ArrayList<Object> stack = new ArrayList<>();
    stack.add(root);
    long totalSize = 0;
    while (!stack.isEmpty()) {
        final Object ob = stack.remove(stack.size() - 1);
        if (ob == null || seen.contains(ob)) {
            continue;
        }
        seen.add(ob);
        final Class<?> obClazz = ob.getClass();
        assert obClazz != null : "jvm bug detected (Object.getClass() == null). please report this to your vendor";
        if (obClazz.isArray()) {
            /*
         * Consider an array, possibly of primitive types. Push any of its references to
         * the processing stack and accumulate this array's shallow size. 
         */
            final long shallowSize = RamUsageEstimator.shallowSizeOf(ob);
            final int len = Array.getLength(ob);
            final List<Object> values;
            Class<?> componentClazz = obClazz.getComponentType();
            if (componentClazz.isPrimitive()) {
                values = Collections.emptyList();
            } else {
                values = new AbstractList<Object>() {

                    @Override
                    public Object get(int index) {
                        return Array.get(ob, index);
                    }

                    @Override
                    public int size() {
                        return len;
                    }
                };
            }
            totalSize += accumulator.accumulateArray(ob, shallowSize, values, stack);
        } else {
            /*
         * Consider an object. Push any references it has to the processing stack
         * and accumulate this object's shallow size. 
         */
            try {
                ClassCache cachedInfo = classCache.get(obClazz);
                if (cachedInfo == null) {
                    classCache.put(obClazz, cachedInfo = createCacheEntry(obClazz));
                }
                boolean needsReflection = true;
                if (Constants.JRE_IS_MINIMUM_JAVA9 && obClazz.getName().startsWith("java.")) {
                    // Java 9: Best guess for some known types, as we cannot precisely look into runtime classes:
                    final ToLongFunction<Object> func = SIMPLE_TYPES.get(obClazz);
                    if (func != null) {
                        // some simple type like String where the size is easy to get from public properties
                        totalSize += accumulator.accumulateObject(ob, cachedInfo.alignedShallowInstanceSize + func.applyAsLong(ob), Collections.emptyMap(), stack);
                        needsReflection = false;
                    } else if (ob instanceof Iterable) {
                        final List<Object> values = StreamSupport.stream(((Iterable<?>) ob).spliterator(), false).collect(Collectors.toList());
                        totalSize += accumulator.accumulateArray(ob, cachedInfo.alignedShallowInstanceSize + RamUsageEstimator.NUM_BYTES_ARRAY_HEADER, values, stack);
                        needsReflection = false;
                    } else if (ob instanceof Map) {
                        final List<Object> values = ((Map<?, ?>) ob).entrySet().stream().flatMap(e -> Stream.of(e.getKey(), e.getValue())).collect(Collectors.toList());
                        totalSize += accumulator.accumulateArray(ob, cachedInfo.alignedShallowInstanceSize + RamUsageEstimator.NUM_BYTES_ARRAY_HEADER, values, stack);
                        totalSize += RamUsageEstimator.NUM_BYTES_ARRAY_HEADER;
                        needsReflection = false;
                    }
                }
                if (needsReflection) {
                    final Map<Field, Object> fieldValues = new HashMap<>();
                    for (Field f : cachedInfo.referenceFields) {
                        fieldValues.put(f, f.get(ob));
                    }
                    totalSize += accumulator.accumulateObject(ob, cachedInfo.alignedShallowInstanceSize, fieldValues, stack);
                }
            } catch (IllegalAccessException e) {
                // this should never happen as we enabled setAccessible().
                throw new RuntimeException("Reflective field access failed?", e);
            }
        }
    }
    // Help the GC (?).
    seen.clear();
    stack.clear();
    classCache.clear();
    return totalSize;
}