[GitHub] [ignite-3] AMashenkov commented on a change in pull request #105: IGNITE-14407 introduced in-memory vault implementation

[GitBox <gi...@apache.org>]

AMashenkov commented on a change in pull request #105:
URL: https://github.com/apache/ignite-3/pull/105#discussion_r619275184



##########
File path: modules/core/src/main/java/org/apache/ignite/lang/ByteArray.java
##########
@@ -0,0 +1,98 @@
+/*
+ * 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.ignite.lang;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A class for handling byte array.
+ */
+public final class ByteArray implements Comparable<ByteArray> {
+    /** Byte-wise representation of the {@code ByteArray}. */
+    @NotNull
+    private final byte[] arr;
+
+    /**
+     * Constructs {@code ByteArray} instance from the given byte array. <em>Note:</em> copy of the given byte array will not be
+     * created in order to avoid redundant memory consumption.
+     *
+     * @param arr Byte array. Can't be {@code null}.
+     */
+    public ByteArray(@NotNull byte[] arr) {
+        this.arr = arr;
+    }
+
+    /**
+     * Constructs {@code ByteArray} instance from the given string.
+     *
+     * @param s The string {@code ByteArray} representation. Can't be {@code null}.
+     */
+    public static ByteArray fromString(@NotNull String s) {
+        return new ByteArray(s.getBytes(StandardCharsets.UTF_8));
+    }
+
+    /**
+     * Returns the {@code ByteArray} as byte array.
+     *
+     * @return Bytes of the {@code ByteArray}.
+     */
+    public byte[] bytes() {
+        return arr;
+    }
+
+    /** {@inheritDoc} */
+    @Override public boolean equals(Object o) {
+        if (this == o) return true;
+
+        if (o == null || getClass() != o.getClass()) return false;
+
+        ByteArray byteArray = (ByteArray)o;
+
+        return Arrays.equals(arr, byteArray.arr);
+    }
+
+    /** {@inheritDoc} */
+    @Override public int hashCode() {
+        return Arrays.hashCode(arr);

Review comment:
       Arrays.hashcode uses `hash += 31*hash + a[i]`  in a loop.
   Does anyone know if JVMs can unroll the loop and vectorize this well?
   I've read discussions about that and manual unrolling gives ~1.5-2x boost.
   
   int i = 0
   for (;I<= a.length-4; i+=4) {
     hash += 31*31*31*31 * a[i];
     hash += 31*31*31 * a[i+1];
     hash += 31* a[i + 2];
     hash += a[i + 3];
   }
   for (;I<= a.length; i++) 
     hash += 31* a[i];
   




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