Adding JMCR-Stable version

[Benchmarks_CSolver.git] / JMCR-Stable / real-world application / derby-10.3.2.1 / java / drda / org / apache / derby / impl / drda / ConsistencyToken.java

diff --git a/JMCR-Stable/real-world application/derby-10.3.2.1/java/drda/org/apache/derby/impl/drda/ConsistencyToken.java b/JMCR-Stable/real-world application/derby-10.3.2.1/java/drda/org/apache/derby/impl/drda/ConsistencyToken.java
new file mode 100644 (file)
index 0000000..eaaf4e9
--- /dev/null
+++ b/JMCR-Stable/real-world application/derby-10.3.2.1/java/drda/org/apache/derby/impl/drda/ConsistencyToken.java
@@ -0,0 +1,102 @@
+/*\r
+ * Derby - class org.apache.derby.impl.drda.ConsistencyToken\r
+ *\r
+ * Licensed to the Apache Software Foundation (ASF) under one or more\r
+ * contributor license agreements.  See the NOTICE file distributed with\r
+ * this work for additional information regarding copyright ownership.\r
+ * The ASF licenses this file to You under the Apache License, Version 2.0\r
+ * (the "License"); you may not use this file except in compliance with\r
+ * the License.  You may obtain a copy of the License at\r
+ *\r
+ *   http://www.apache.org/licenses/LICENSE-2.0\r
+ *\r
+ * Unless required by applicable law or agreed to in writing, software\r
+ * distributed under the License is distributed on an "AS IS" BASIS,\r
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or\r
+ * implied. See the License for the specific language governing\r
+ * permissions and limitations under the License.\r
+ *\r
+ */\r
+\r
+package org.apache.derby.impl.drda;\r
+\r
+/**\r
+ * Class which represents an RDB Package Consistency Token.\r
+ */\r
+final class ConsistencyToken {\r
+    /** Byte array representation of the token. */\r
+    private final byte[] bytes;\r
+    /** Cached hash code. */\r
+    private int hash = 0;\r
+\r
+    /**\r
+     * Create a new <code>ConsistencyToken</code> instance.\r
+     *\r
+     * @param bytes byte array representing the token\r
+     */\r
+    ConsistencyToken(byte[] bytes) {\r
+        this.bytes = bytes;\r
+    }\r
+\r
+    /**\r
+     * Get the byte array representation of the consistency token.\r
+     *\r
+     * @return a <code>byte[]</code> value\r
+     */\r
+    public byte[] getBytes() {\r
+        return bytes;\r
+    }\r
+\r
+    /**\r
+     * Check whether this object is equal to another object.\r
+     *\r
+     * @param o another object\r
+     * @return true if the objects are equal\r
+     */\r
+    public boolean equals(Object o) {\r
+        if (!(o instanceof ConsistencyToken)) return false;\r
+        ConsistencyToken ct = (ConsistencyToken) o;\r
+        int len = bytes.length;\r
+        if (len != ct.bytes.length) return false;\r
+        for (int i = 0; i < len; ++i) {\r
+            if (bytes[i] != ct.bytes[i]) return false;\r
+        }\r
+        return true;\r
+    }\r
+\r
+    /**\r
+     * Calculate the hash code.\r
+     *\r
+     * @return hash code\r
+     */\r
+    public int hashCode() {\r
+        // ConsistencyToken objects might be kept for a long time and are\r
+        // frequently used as keys in hash tables. Therefore, it is a good idea\r
+        // to cache their hash codes.\r
+        int h = hash;\r
+        if (h == 0) {\r
+            // The hash code has not been calculated yet (or perhaps the hash\r
+            // code actually is 0). Calculate a new one and cache it. No\r
+            // synchronization is needed since reads and writes of 32-bit\r
+            // primitive values are guaranteed to be atomic. See The\r
+            // "Double-Checked Locking is Broken" Declaration for details.\r
+            int len = bytes.length;\r
+            for (int i = 0; i < len; ++i) {\r
+                h ^= bytes[i];\r
+            }\r
+            hash = h;\r
+        }\r
+        return h;\r
+    }\r
+\r
+    /**\r
+     * Return a string representation of the consistency token by\r
+     * converting it to a <code>BigInteger</code> value. (For\r
+     * debugging only.)\r
+     *\r
+     * @return a <code>String</code> value\r
+     */\r
+    public String toString() {\r
+        return new java.math.BigInteger(bytes).toString();\r
+    }\r
+}\r