[#noissue] Optimize TagUtils

Author: emeroad

inspector-module/inspector-commons/src/main/java/com/navercorp/pinpoint/common/dao/pinot/MultiValueTagTypeHandler.java

@@ -17,11 +17,12 @@
 package com.navercorp.pinpoint.common.dao.pinot;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectReader;
 import com.navercorp.pinpoint.common.server.util.json.Jackson;
 import com.navercorp.pinpoint.metric.common.model.Tag;
 import com.navercorp.pinpoint.metric.common.util.TagUtils;
+import org.apache.commons.lang3.StringUtils;
 import org.apache.ibatis.type.JdbcType;
 import org.apache.ibatis.type.TypeHandler;
 
@@ -30,15 +31,13 @@
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.List;
-import java.util.stream.Collectors;
 
 /**
  * @author minwoo.jung
  */
 public class MultiValueTagTypeHandler implements TypeHandler<List<Tag>> {
 
-    private final static ObjectMapper MAPPER = getMapper();
-    private final static JavaType LISTSTRING_JavaType = MAPPER.getTypeFactory().constructCollectionType(List.class, String.class);
+    private final static ObjectReader READER = getMapper().readerForListOf(String.class);
 
     private static ObjectMapper getMapper() {
         return Jackson.newBuilder()
@@ -52,12 +51,13 @@ public void setParameter(PreparedStatement ps, int i, List<Tag> parameter, JdbcT
 
     @Override
     public List<Tag> getResult(ResultSet rs, String columnName) throws SQLException {
-        String json = rs.getString(columnName);
+        final String json = rs.getString(columnName);
+        if (StringUtils.isEmpty(json)) {
+            return List.of();
+        }
         try {
-            List<String> tags = MAPPER.readValue(json, LISTSTRING_JavaType);
-            return tags.stream()
-                    .map(TagUtils::parseTag)
-                    .collect(Collectors.toList());
+            List<String> tags = READER.readValue(json);
+            return TagUtils.parseTags(tags);
         } catch (JsonProcessingException e) {
             throw new SQLException(e);
         }

metric-module/metric-commons/src/main/java/com/navercorp/pinpoint/metric/common/util/TagUtils.java

@@ -24,8 +24,8 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.StringJoiner;
 import java.util.regex.Pattern;
-import java.util.stream.Collectors;
 
 /**
  * @author Hyunjoon Cho
@@ -40,10 +40,10 @@ private TagUtils() {
 
     public static List<Tag> parseTags(List<String> tags) {
         if (CollectionUtils.isEmpty(tags)) {
-            return new ArrayList<>();
+            return List.of();
         }
 
-        List<Tag> tagList = new ArrayList<>();
+        List<Tag> tagList = new ArrayList<>(tags.size());
         for (String tagString : tags) {
             Tag tag = parseTag(tagString);
             tagList.add(tag);
@@ -53,12 +53,12 @@ public static List<Tag> parseTags(List<String> tags) {
 
     public static List<Tag> parseTags(String tagStrings) {
         if (tagStrings == null || tagStrings.contains("null")) {
-            return new ArrayList<>();
+            return List.of();
         }
 
-        List<Tag> tagList = new ArrayList<>();
-
         String[] tagStrArray = parseMultiValueFieldList(tagStrings);
+
+        List<Tag> tagList = new ArrayList<>(tagStrArray.length);
         for (String tagString : tagStrArray) {
             Tag tag = parseTag(tagString);
             tagList.add(tag);
@@ -94,8 +94,10 @@ public static String toTagString(String jsonTagString) {
     }
 
     public static String toTagString(List<Tag> tagList) {
-        return tagList.stream()
-                .map(Tag::toString)
-                .collect(Collectors.joining(","));
+        StringJoiner joiner = new StringJoiner(",");
+        for (Tag tag : tagList) {
+            joiner.add(tag.toString());
+        }
+        return joiner.toString();
     }
 }