Reduce the toCharArray overhead

Both the PatternMatcher and JdbcParameterUtils use String.toCharArray for
processing. This will create a new char[] which needs to be collected. The
same code has been rewritten to use String.charAt to reduce the overhead.

Additionally unneeded object creation in the PatternMatcher has been removed
as well, to reduce further objects needed to be gc'ed.

Author: mdeinum

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/database/JdbcParameterUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@
  *
  * @author Thomas Risberg
  * @author Juergen Hoeller
+ * @author Marten Deinum
  * @since 2.0
  */
 public class JdbcParameterUtils {
@@ -53,30 +54,29 @@ public static int countParameterPlaceholders(String sql, List<String> namedParam
 			return 0;
 		}
 
-		char[] statement = sql.toCharArray();
 		boolean withinQuotes = false;
 		Map<String, StringBuilder> namedParameters = new HashMap<>();
 		char currentQuote = '-';
 		int parameterCount = 0;
 		int i = 0;
-		while (i < statement.length) {
+		while (i < sql.length()) {
 			if (withinQuotes) {
-				if (statement[i] == currentQuote) {
+				if (sql.charAt(i) == currentQuote) {
 					withinQuotes = false;
 					currentQuote = '-';
 				}
 			}
 			else {
-				if (statement[i] == '"' || statement[i] == '\'') {
+				if (sql.charAt(i) == '"' || sql.charAt(i) == '\'') {
 					withinQuotes = true;
-					currentQuote = statement[i];
+					currentQuote = sql.charAt(i);
 				}
 				else {
-					if (statement[i] == ':' || statement[i] == '&') {
+					if (sql.charAt(i) == ':' || sql.charAt(i) == '&') {
 						int j = i + 1;
 						StringBuilder parameter = new StringBuilder();
-						while (j < statement.length && parameterNameContinues(statement, j)) {
-							parameter.append(statement[j]);
+						while (j < sql.length() && parameterNameContinues(sql, j)) {
+							parameter.append(sql.charAt(j));
 							j++;
 						}
 						if (j - i > 1) {
@@ -88,7 +88,7 @@ public static int countParameterPlaceholders(String sql, List<String> namedParam
 						}
 					}
 					else {
-						if (statement[i] == '?') {
+						if (sql.charAt(i) == '?') {
 							parameterCount++;
 						}
 					}
@@ -108,10 +108,11 @@ public static int countParameterPlaceholders(String sql, List<String> namedParam
 	 * @param statement the SQL statement
 	 * @param pos the position within the statement
 	 */
-	private static boolean parameterNameContinues(char[] statement, int pos) {
-		return (statement[pos] != ' ' && statement[pos] != ',' && statement[pos] != ')' &&
-				statement[pos] != '"' && statement[pos] != '\'' && statement[pos] != '|' &&
-				statement[pos] != ';' && statement[pos] != '\n' && statement[pos] != '\r');
+	private static boolean parameterNameContinues(String statement, int pos) {
+		char character = statement.charAt(pos);
+		return (character != ' ' && character != ',' && character != ')' &&
+				character != '"' && character != '\'' && character != '|' &&
+				character != ';' && character != '\n' && character != '\r');
 	}
 
 }

spring-batch-infrastructure/src/main/java/org/springframework/batch/support/PatternMatcher.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2007 the original author or authors.
+ * Copyright 2006-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,9 +16,7 @@
 package org.springframework.batch.support;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.Comparator;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -27,11 +25,12 @@
 /**
  * @author Dave Syer
  * @author Dan Garrette
+ * @author Marten Deinum
  */
 public class PatternMatcher<S> {
 
-	private Map<String, S> map = new HashMap<>();
-	private List<String> sorted = new ArrayList<>();
+	private final Map<String, S> map;
+	private final List<String> sorted;
 
 	/**
 	 * Initialize a new {@link PatternMatcher} with a map of patterns to values
@@ -42,14 +41,7 @@ public PatternMatcher(Map<String, S> map) {
 		this.map = map;
 		// Sort keys to start with the most specific
 		sorted = new ArrayList<>(map.keySet());
-		Collections.sort(sorted, new Comparator<String>() {
-            @Override
-			public int compare(String o1, String o2) {
-				String s1 = o1; // .replace('?', '{');
-				String s2 = o2; // .replace('*', '}');
-				return s2.compareTo(s1);
-			}
-		});
+		sorted.sort(Comparator.reverseOrder());
 	}
 
 	/**
@@ -66,12 +58,10 @@ public int compare(String o1, String o2) {
 	 * <code>false</code> otherwise.
 	 */
 	public static boolean match(String pattern, String str) {
-		char[] patArr = pattern.toCharArray();
-		char[] strArr = str.toCharArray();
 		int patIdxStart = 0;
-		int patIdxEnd = patArr.length - 1;
+		int patIdxEnd = pattern.length() - 1;
 		int strIdxStart = 0;
-		int strIdxEnd = strArr.length - 1;
+		int strIdxEnd = str.length() - 1;
 		char ch;
 
 		boolean containsStar = pattern.contains("*");
@@ -82,9 +72,9 @@ public static boolean match(String pattern, String str) {
 				return false; // Pattern and string do not have the same size
 			}
 			for (int i = 0; i <= patIdxEnd; i++) {
-				ch = patArr[i];
+				ch = pattern.charAt(i);
 				if (ch != '?') {
-					if (ch != strArr[i]) {
+					if (ch != str.charAt(i)) {
 						return false;// Character mismatch
 					}
 				}
@@ -97,9 +87,9 @@ public static boolean match(String pattern, String str) {
 		}
 
 		// Process characters before first star
-		while ((ch = patArr[patIdxStart]) != '*' && strIdxStart <= strIdxEnd) {
+		while ((ch = pattern.charAt(patIdxStart)) != '*' && strIdxStart <= strIdxEnd) {
 			if (ch != '?') {
-				if (ch != strArr[strIdxStart]) {
+				if (ch != str.charAt(strIdxStart)) {
 					return false;// Character mismatch
 				}
 			}
@@ -110,17 +100,17 @@ public static boolean match(String pattern, String str) {
 			// All characters in the string are used. Check if only '*'s are
 			// left in the pattern. If so, we succeeded. Otherwise failure.
 			for (int i = patIdxStart; i <= patIdxEnd; i++) {
-				if (patArr[i] != '*') {
+				if (pattern.charAt(i) != '*') {
 					return false;
 				}
 			}
 			return true;
 		}
 
 		// Process characters after last star
-		while ((ch = patArr[patIdxEnd]) != '*' && strIdxStart <= strIdxEnd) {
+		while ((ch = pattern.charAt(patIdxEnd)) != '*' && strIdxStart <= strIdxEnd) {
 			if (ch != '?') {
-				if (ch != strArr[strIdxEnd]) {
+				if (ch != str.charAt(strIdxEnd)) {
 					return false;// Character mismatch
 				}
 			}
@@ -131,7 +121,7 @@ public static boolean match(String pattern, String str) {
 			// All characters in the string are used. Check if only '*'s are
 			// left in the pattern. If so, we succeeded. Otherwise failure.
 			for (int i = patIdxStart; i <= patIdxEnd; i++) {
-				if (patArr[i] != '*') {
+				if (pattern.charAt(i) != '*') {
 					return false;
 				}
 			}
@@ -143,7 +133,7 @@ public static boolean match(String pattern, String str) {
 		while (patIdxStart != patIdxEnd && strIdxStart <= strIdxEnd) {
 			int patIdxTmp = -1;
 			for (int i = patIdxStart + 1; i <= patIdxEnd; i++) {
-				if (patArr[i] == '*') {
+				if (pattern.charAt(i) == '*') {
 					patIdxTmp = i;
 					break;
 				}
@@ -160,9 +150,9 @@ public static boolean match(String pattern, String str) {
 			int foundIdx = -1;
 			strLoop: for (int i = 0; i <= strLength - patLength; i++) {
 				for (int j = 0; j < patLength; j++) {
-					ch = patArr[patIdxStart + j + 1];
+					ch = pattern.charAt(patIdxStart + j + 1);
 					if (ch != '?') {
-						if (ch != strArr[strIdxStart + i + j]) {
+						if (ch != str.charAt(strIdxStart + i + j)) {
 							continue strLoop;
 						}
 					}
@@ -183,7 +173,7 @@ public static boolean match(String pattern, String str) {
 		// All characters in the string are used. Check if only '*'s are left
 		// in the pattern. If so, we succeeded. Otherwise failure.
 		for (int i = patIdxStart; i <= patIdxEnd; i++) {
-			if (patArr[i] != '*') {
+			if (pattern.charAt(i) != '*') {
 				return false;
 			}
 		}