Use ConcurrentMap and Collections.unmodifiableMap()

Author: kcooney

core/src/main/java/com/team2813/lib2813/preferences/PersistedConfiguration.java

@@ -27,9 +27,12 @@
 import edu.wpi.first.wpilibj.DriverStation;
 import edu.wpi.first.wpilibj.Preferences;
 import java.lang.reflect.*;
+import java.util.Collections;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
@@ -401,34 +404,40 @@ Object getValue(
         ListenerRegistry listenerRegistry);
   }
 
-  private static final Map<Type, PreferenceFetcher> TYPE_TO_FETCHER = new HashMap<>();
+  private static final Map<Type, PreferenceFetcher> TYPE_TO_FETCHER = createTypeToFetcherMap();
 
   /**
    * Registers a preference fetcher with a type.
    *
+   * @param typeToFetcher The map to update.
    * @param type The type to register.
-   * @param simpleFetcher The fetcher that should be used to create values of the given type.
+   * @param genericFetcher The fetcher that should be used to create values of the given type.
    */
   @SuppressWarnings("unchecked")
-  private static <T> void register(Class<T> type, GenericPreferenceFetcher<T> simpleFetcher) {
+  private static <T> void register(
+      Map<Type, PreferenceFetcher> typeToFetcher,
+      Class<T> type,
+      GenericPreferenceFetcher<T> genericFetcher) {
     PreferenceFetcher fetcher =
         (component, key, defaultValue, initializePreference, listenerConsumers) ->
-            simpleFetcher.getValue(
+            genericFetcher.getValue(
                 component, key, (T) defaultValue, initializePreference, listenerConsumers);
-    TYPE_TO_FETCHER.put(type, fetcher);
+    typeToFetcher.put(type, fetcher);
   }
 
-  static {
-    register(Boolean.TYPE, PersistedConfiguration::booleanFetcher);
-    register(BooleanSupplier.class, PersistedConfiguration::booleanSupplierFetcher);
-    register(Integer.TYPE, PersistedConfiguration::intFetcher);
-    register(IntSupplier.class, PersistedConfiguration::intSupplierFetcher);
-    register(Long.TYPE, PersistedConfiguration::longFetcher);
-    register(LongSupplier.class, PersistedConfiguration::longSupplierFetcher);
-    register(Double.TYPE, PersistedConfiguration::doubleFetcher);
-    register(DoubleSupplier.class, PersistedConfiguration::doubleSupplierFetcher);
-    register(String.class, PersistedConfiguration::stringFetcher);
-    register(Supplier.class, PersistedConfiguration::supplierFetcher);
+  private static Map<Type, PreferenceFetcher> createTypeToFetcherMap() {
+    Map<Type, PreferenceFetcher> map = new HashMap<>();
+    register(map, Boolean.TYPE, PersistedConfiguration::booleanFetcher);
+    register(map, BooleanSupplier.class, PersistedConfiguration::booleanSupplierFetcher);
+    register(map, Integer.TYPE, PersistedConfiguration::intFetcher);
+    register(map, IntSupplier.class, PersistedConfiguration::intSupplierFetcher);
+    register(map, Long.TYPE, PersistedConfiguration::longFetcher);
+    register(map, LongSupplier.class, PersistedConfiguration::longSupplierFetcher);
+    register(map, Double.TYPE, PersistedConfiguration::doubleFetcher);
+    register(map, DoubleSupplier.class, PersistedConfiguration::doubleSupplierFetcher);
+    register(map, String.class, PersistedConfiguration::stringFetcher);
+    register(map, Supplier.class, PersistedConfiguration::supplierFetcher);
+    return Collections.unmodifiableMap(map);
   }
 
   /** Gets a boolean value from Preferences for the given component. */
@@ -721,7 +730,8 @@ private PersistedConfiguration() {
   /** Registry that supports adding Preference value listeners. */
   private static class ListenerRegistry {
     private static final String PREFERENCE_TABLE_NAME = "Preferences";
-    private final Map<Integer, Consumer<NetworkTableValue>> topicToConsumer = new HashMap<>();
+    private final ConcurrentMap<Integer, Consumer<NetworkTableValue>> topicToConsumer =
+        new ConcurrentHashMap<>();
     private final NetworkTable preferencesTable;
 
     ListenerRegistry(NetworkTableInstance ntInstance, String preferenceName) {