Implemented DifficultyService IpAddressMatcher cache

Author: tobiasholler

captchaservice-backend/src/main/java/de/muenchen/captchaservice/service/difficulty/DifficultyService.java

@@ -12,7 +12,9 @@
 import org.springframework.stereotype.Service;
 
 import java.time.Instant;
+import java.util.Map;
 import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
 
 @Service
 @Slf4j
@@ -22,6 +24,8 @@ public class DifficultyService {
 
     private final CaptchaRequestRepository captchaRequestRepository;
 
+    private final Map<String, IpAddressMatcher> matcherCache = new ConcurrentHashMap<>();
+
     @SuppressFBWarnings(value = { "EI_EXPOSE_REP2" }, justification = "Dependency Injection")
     public DifficultyService(final CaptchaProperties captchaProperties, final CaptchaRequestRepository captchaRequestRepository) {
         this.captchaProperties = captchaProperties;
@@ -65,7 +69,8 @@ public long getDifficultyForSourceAddress(final String siteKey, final SourceAddr
     public boolean isSourceAddressWhitelisted(final String siteKey, final SourceAddress sourceAddress) {
         final CaptchaSite captchaSite = captchaProperties.sites().get(siteKey);
         for (String subnet : captchaSite.whitelistedSourceAddresses()) {
-            if (new IpAddressMatcher(subnet).matches(sourceAddress.getSourceAddress())) return true;
+            IpAddressMatcher matcher = matcherCache.computeIfAbsent(subnet, IpAddressMatcher::new);
+            if (matcher.matches(sourceAddress.getSourceAddress())) return true;
         }
         return false;
     }