From 935c29e3ddba5b19951e54f6685c70ed45d9cbe5 Mon Sep 17 00:00:00 2001
From: Sam Brannen <sam@sambrannen.com>
Date: Fri, 17 Mar 2023 12:12:22 +0100
Subject: [PATCH] Increase scope of regex pattern cache for the SpEL `matches`
 operator

Prior to this commit, the pattern cache for the SpEL `matches` operator
only applied to expressions such as the following where the same
`matches` operator is invoked multiple times with different input:

  "map.keySet().?[#this matches '.+xyz']"

The pattern cache did not apply to expressions such as the following
where the same pattern ('.+xyz') is used in multiple `matches`
operations:

  "foo matches '.+xyz' AND bar matches '.+xyz'"

This commit addresses this by moving the instance of the pattern cache
map from OperatorMatches to InternalSpelExpressionParser so that the
cache can be reused for all `matches` operations for the given parser.

Closes gh-30140
---
 .../expression/spel/ast/OperatorMatches.java  | 21 ++++++++++++++++---
 .../InternalSpelExpressionParser.java         | 10 +++++++--
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OperatorMatches.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OperatorMatches.java
index 6c9bfbaf3ed5..6c219ba03640 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/OperatorMatches.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/OperatorMatches.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -43,13 +43,28 @@ public class OperatorMatches extends Operator {
 
 	private static final int PATTERN_ACCESS_THRESHOLD = 1000000;
 
-	private final ConcurrentMap<String, Pattern> patternCache = new ConcurrentHashMap<>();
+	private final ConcurrentMap<String, Pattern> patternCache;
 
 
+	/**
+	 * Create a new {@link OperatorMatches} instance.
+	 * @deprecated as of Spring Framework 5.3.26 in favor of invoking
+	 * {@link #OperatorMatches(ConcurrentMap, int, int, SpelNodeImpl...)}
+	 * with a shared pattern cache instead
+	 */
+	@Deprecated(since = "5.3.26")
 	public OperatorMatches(int startPos, int endPos, SpelNodeImpl... operands) {
-		super("matches", startPos, endPos, operands);
+		this(new ConcurrentHashMap<>(), startPos, endPos, operands);
 	}
 
+	/**
+	 * Create a new {@link OperatorMatches} instance with a shared pattern cache.
+	 * @since 5.3.26
+	 */
+	public OperatorMatches(ConcurrentMap<String, Pattern> patternCache, int startPos, int endPos, SpelNodeImpl... operands) {
+		super("matches", startPos, endPos, operands);
+		this.patternCache = patternCache;
+	}
 
 	/**
 	 * Check the first operand matches the regex specified as the second operand.
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java b/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
index 33c4d9db4eb3..748f8e6bd524 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -21,6 +21,8 @@
 import java.util.Collections;
 import java.util.Deque;
 import java.util.List;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 import java.util.regex.Pattern;
 
 import org.springframework.expression.ParseException;
@@ -83,6 +85,7 @@
  * @author Andy Clement
  * @author Juergen Hoeller
  * @author Phillip Webb
+ * @author Sam Brannen
  * @since 3.0
  */
 class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
@@ -95,6 +98,9 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 	// For rules that build nodes, they are stacked here for return
 	private final Deque<SpelNodeImpl> constructedNodes = new ArrayDeque<>();
 
+	// Shared cache for compiled regex patterns
+	private final ConcurrentMap<String, Pattern> patternCache = new ConcurrentHashMap<>();
+
 	// The expression being parsed
 	private String expressionString = "";
 
@@ -248,7 +254,7 @@ private SpelNodeImpl eatRelationalExpression() {
 			}
 
 			if (tk == TokenKind.MATCHES) {
-				return new OperatorMatches(t.startPos, t.endPos, expr, rhExpr);
+				return new OperatorMatches(this.patternCache, t.startPos, t.endPos, expr, rhExpr);
 			}
 
 			Assert.isTrue(tk == TokenKind.BETWEEN, "Between token expected");