cpu usage reduced on TbNodeUtils

@@ -39,12 +39,8 @@ public class TbNodeUtils {
 
     private static final ObjectMapper mapper = new ObjectMapper();
 
-    private static final String METADATA_VARIABLE_TEMPLATE = "${%s}";
-
     private static final Pattern DATA_PATTERN = Pattern.compile("(\\$\\[)(.*?)(])");
 
-    private static final String DATA_VARIABLE_TEMPLATE = "$[%s]";
-
     public static <T> T convert(TbNodeConfiguration configuration, Class<T> clazz) throws TbNodeException {
         try {
             return mapper.treeToValue(configuration.getData(), clazz);
@@ -80,7 +76,7 @@ public class TbNodeUtils {
                     }
 
                     if (jsonNode != null && jsonNode.isValueNode()) {
-                        result = result.replace(String.format(DATA_VARIABLE_TEMPLATE, group), jsonNode.asText());
+                        result = result.replace(formatDataVarTemplate(group), jsonNode.asText());
                     }
                 }
             }
@@ -106,8 +102,14 @@ public class TbNodeUtils {
     }
 
     private static String processVar(String pattern, String key, String val) {
-        String varPattern = String.format(METADATA_VARIABLE_TEMPLATE, key);
-        return pattern.replace(varPattern, val);
+        return pattern.replace(formatMetadataVarTemplate(key), val);
     }
 
+    static String formatDataVarTemplate(String key) {
+        return "$[" + key + ']';
+    }
+
+    static String formatMetadataVarTemplate(String key) {
+        return "${" + key + '}';
+    }
 }

@@ -16,6 +16,7 @@
 package org.thingsboard.rule.engine.api.util;
 
 import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.hamcrest.CoreMatchers;
 import org.junit.Assert;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -25,9 +26,15 @@ import org.thingsboard.server.common.msg.TbMsg;
 import org.thingsboard.server.common.msg.TbMsgMetaData;
 import org.thingsboard.common.util.JacksonUtil;
 
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+
 @RunWith(MockitoJUnitRunner.class)
 public class TbNodeUtilsTest {
 
+    private static final String DATA_VARIABLE_TEMPLATE = "$[%s]";
+    private static final String METADATA_VARIABLE_TEMPLATE = "${%s}";
+
     @Test
     public void testSimpleReplacement() {
         String pattern = "ABC ${metadata_key} $[data_key]";
@@ -112,4 +119,27 @@ public class TbNodeUtilsTest {
         Assert.assertEquals("ABC metadata_value $[key1.key2[0].key3]", result);
     }
 
+    @Test
+    public void givenKey_whenFormatDataVarTemplate_thenReturnTheSameStringAsFormat() {
+        assertThat(TbNodeUtils.formatDataVarTemplate("key"), is("$[key]"));
+        assertThat(TbNodeUtils.formatDataVarTemplate("key"), is(String.format(DATA_VARIABLE_TEMPLATE, "key")));
+
+        assertThat(TbNodeUtils.formatDataVarTemplate(""), is("$[]"));
+        assertThat(TbNodeUtils.formatDataVarTemplate(""), is(String.format(DATA_VARIABLE_TEMPLATE, "")));
+
+        assertThat(TbNodeUtils.formatDataVarTemplate(null), is("$[null]"));
+        assertThat(TbNodeUtils.formatDataVarTemplate(null), is(String.format(DATA_VARIABLE_TEMPLATE, (String) null)));
+    }
+
+    @Test
+    public void givenKey_whenFormatMetadataVarTemplate_thenReturnTheSameStringAsFormat() {
+        assertThat(TbNodeUtils.formatMetadataVarTemplate("key"), is("${key}"));
+        assertThat(TbNodeUtils.formatMetadataVarTemplate("key"), is(String.format(METADATA_VARIABLE_TEMPLATE, "key")));
+
+        assertThat(TbNodeUtils.formatMetadataVarTemplate(""), is("${}"));
+        assertThat(TbNodeUtils.formatMetadataVarTemplate(""), is(String.format(METADATA_VARIABLE_TEMPLATE, "")));
+
+        assertThat(TbNodeUtils.formatMetadataVarTemplate(null), is("${null}"));
+        assertThat(TbNodeUtils.formatMetadataVarTemplate(null), is(String.format(METADATA_VARIABLE_TEMPLATE, (String) null)));
+    }
 }