[GitHub] merlimat commented on a change in pull request #826: DbLedgerStorage implementation

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merlimat commented on a change in pull request #826: DbLedgerStorage implementation
URL: https://github.com/apache/bookkeeper/pull/826#discussion_r155928539
 
 

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 File path: bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/ArrayUtil.java
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 @@ -0,0 +1,77 @@
+/**
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.bookkeeper.bookie.storage.ldb;
+
+// CHECKSTYLE.OFF: IllegalImport
+import io.netty.util.internal.PlatformDependent;
+// CHECKSTYLE.ON: IllegalImport
+
+import java.nio.ByteOrder;
+
+/**
+ * Utility to serialize/deserialize longs into byte arrays.
+ */
+class ArrayUtil {
+
+    private static final boolean UNALIGNED = PlatformDependent.isUnaligned();
+    private static final boolean HAS_UNSAFE = PlatformDependent.hasUnsafe();
+    private static final boolean BIG_ENDIAN_NATIVE_ORDER = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN;
+
+    public static long getLong(byte[] array, int index) {
+        if (HAS_UNSAFE && UNALIGNED) {
+            long v = PlatformDependent.getLong(array, index);
+            return BIG_ENDIAN_NATIVE_ORDER ? v : Long.reverseBytes(v);
+        }
+
+        return ((long) array[index] & 0xff) << 56 | //
+                ((long) array[index + 1] & 0xff) << 48 | //
+                ((long) array[index + 2] & 0xff) << 40 | //
+                ((long) array[index + 3] & 0xff) << 32 | //
+                ((long) array[index + 4] & 0xff) << 24 | //
+                ((long) array[index + 5] & 0xff) << 16 | //
+                ((long) array[index + 6] & 0xff) << 8 | //
+                (long) array[index + 7] & 0xff;
+    }
+
+    public static void setLong(byte[] array, int index, long value) {
+        if (HAS_UNSAFE && UNALIGNED) {
+            PlatformDependent.putLong(array, index, BIG_ENDIAN_NATIVE_ORDER ? value : Long.reverseBytes(value));
+        } else {
+            array[index] = (byte) (value >>> 56);
+            array[index + 1] = (byte) (value >>> 48);
+            array[index + 2] = (byte) (value >>> 40);
+            array[index + 3] = (byte) (value >>> 32);
+            array[index + 4] = (byte) (value >>> 24);
+            array[index + 5] = (byte) (value >>> 16);
+            array[index + 6] = (byte) (value >>> 8);
+            array[index + 7] = (byte) value;
+        }
+    }
+
+    public static final boolean isArrayAllZeros(final byte[] array) {
+        int sum = 0;
+        for (byte b : array) {
+            sum |= b;
 
 Review comment:
   The theory is that removing the branching should get the optimizer job much easier, since it can then unroll the loop. 
   
   This is only used to check for empty master key, so it won't be a long array in any case.

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