Use a compiled pattern instead of parsing it every time (#6107)

* Use a compiled pattern instead of parsing it every time

* Add changelog

Author: sugmanue

.changes/next-release/feature-AWSSDKforJavav2-b051142.json

@@ -0,0 +1,6 @@
+{
+    "category": "AWS SDK for Java v2", 
+    "contributor": "", 
+    "type": "feature", 
+    "description": "Small optimization for endpoint rules. Lazily compile the region pattern instead of parsing it every time. This will pay the penalty of parsing it just once at the cost of using a bit more of memory to keep the parsed pattern."
+}

codegen/src/main/resources/software/amazon/awssdk/codegen/rules/Partition.java.resource

@@ -1,5 +1,6 @@
 import java.util.HashMap;
 import java.util.Map;
+import java.util.regex.Pattern;
 import software.amazon.awssdk.annotations.SdkInternalApi;
 import software.amazon.awssdk.protocols.jsoncore.JsonNode;
 import software.amazon.awssdk.utils.ToString;
@@ -15,6 +16,7 @@ public class Partition {
     private final String regionRegex;
     private final Map<String, RegionOverride> regions;
     private final Outputs outputs;
+    private Pattern regionPattern;
 
     private Partition(Builder builder) {
         this.id = builder.id;
@@ -31,6 +33,13 @@ public class Partition {
         return regionRegex;
     }
 
+    public boolean regionMatches(String region) {
+        if (regionPattern == null) {
+            regionPattern = Pattern.compile(regionRegex);
+        }
+        return regionPattern.matcher(region).matches();
+    }
+
     public Map<String, RegionOverride> regions() {
         return regions;
     }

codegen/src/main/resources/software/amazon/awssdk/codegen/rules2/RulesFunctions.java.resource

@@ -90,8 +90,7 @@ public class RulesFunctions {
         if (matchedPartition == null) {
             // try matching on region name pattern
             for (Partition p : data.partitions) {
-                Pattern regex = Pattern.compile(p.regionRegex());
-                if (regex.matcher(regionName).matches()) {
+                if (p.regionMatches(regionName)) {
                     matchedPartition = p;
                     break;
                 }