Change from MD5 to Checksum (Adler32) for json content dirty detection

ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanPropertyJsonMapper.java

@@ -7,7 +7,7 @@ import io.ebean.core.type.DataReader;
 import io.ebean.core.type.ScalarType;
 import io.ebean.text.TextException;
 import io.ebeaninternal.server.deploy.meta.DeployBeanProperty;
-import io.ebeaninternal.server.util.Md5;
+import io.ebeaninternal.server.util.Checksum;
 
 import javax.persistence.PersistenceException;
 import java.sql.SQLException;
@@ -66,10 +66,14 @@ public class BeanPropertyJsonMapper extends BeanProperty {
 
   private static class Md5MutableHash implements MutableHash {
 
-    private final String md5;
+    private final String hash;
 
     Md5MutableHash(String json) {
-      md5 = Md5.hash(json);
+      this.hash = hash(json);
+    }
+
+    private String hash(String json) {
+      return String.valueOf(Checksum.checksum(json));
     }
 
     @Override
@@ -79,7 +83,7 @@ public class BeanPropertyJsonMapper extends BeanProperty {
 
     @Override
     public boolean isEqualToJson(String json) {
-      return Md5.hash(json).equals(md5);
+      return hash(json).equals(hash);
     }
 
     @Override

ebean-core/src/main/java/io/ebeaninternal/server/util/Checksum.java

@@ -0,0 +1,20 @@
+package io.ebeaninternal.server.util;
+
+import java.nio.charset.StandardCharsets;
+import java.util.zip.Adler32;
+
+/**
+ * Compute a checksum for String content. Use when we desire cheaper option than MD5.
+ */
+public final class Checksum {
+
+  /**
+   * Return the checksum for the given String input.
+   */
+  public static long checksum(String input) {
+    Adler32 adler32 = new Adler32();
+    final byte[] bytes = input.getBytes(StandardCharsets.UTF_8);
+    adler32.update(bytes, 0, bytes.length);
+    return adler32.getValue();
+  }
+}

ebean-core/src/main/java/io/ebeaninternal/server/util/Md5.java

@@ -21,7 +21,6 @@ public final class Md5 {
    * Convert the digest into a hex value.
    */
   private static String digestToHex(byte[] digest) {
-
     StringBuilder sb = new StringBuilder();
     for (byte aDigest : digest) {
       sb.append(Integer.toString((aDigest & 0xff) + 0x100, 16).substring(1));