use ExpiringMap for Pattern Cache

core/pom.xml

@@ -46,6 +46,12 @@
             <version>1.0-SNAPSHOT</version>
             <scope>compile</scope>
         </dependency>
+        <dependency>
+            <groupId>net.jodah</groupId>
+            <artifactId>expiringmap</artifactId>
+            <version>0.5.8</version>
+            <scope>compile</scope>
+        </dependency>
     </dependencies>
     <build>
         <plugins>
@@ -70,6 +76,10 @@
                             <pattern>co.aikar.locales</pattern>
                             <shadedPattern>co.aikar.commands.locales</shadedPattern>
                         </relocation>
+                        <relocation>
+                            <pattern>net.jodah.expiringmap</pattern>
+                            <shadedPattern>co.aikar.commands.lib.expiringmap</shadedPattern>
+                        </relocation>
                     </relocations>
                 </configuration>
             </plugin>

core/src/main/java/co/aikar/commands/ACFPatterns.java

@@ -24,8 +24,11 @@
 package co.aikar.commands;
 
 import com.google.common.collect.Maps;
+import net.jodah.expiringmap.ExpirationPolicy;
+import net.jodah.expiringmap.ExpiringMap;
 
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
 import java.util.regex.Pattern;
 
 @SuppressWarnings("WeakerAccess")
@@ -51,7 +54,12 @@ final class ACFPatterns {
 
     private ACFPatterns() {}
     @SuppressWarnings("Convert2MethodRef")
-    static final Map<String, Pattern> patternCache = Maps.newHashMap();
+    static final Map<String, Pattern> patternCache = ExpiringMap.builder()
+            .maxSize(200)
+            .expiration(1, TimeUnit.HOURS)
+            .expirationPolicy(ExpirationPolicy.ACCESSED)
+            .build();
+
     public static Pattern getPattern(String pattern) {
         return patternCache.computeIfAbsent(pattern, s -> Pattern.compile(pattern));
     }