Merge pull request #23 from tls-attacker/fix-spotbugs-static-write

Fix ST_WRITE_TO_STATIC_FROM_INSTANCE_METHOD SpotBugs issue

Author: ic0ns

src/main/java/de/rub/nds/crawler/persistence/MongoPersistenceProvider.java

@@ -50,15 +50,18 @@ public class MongoPersistenceProvider implements IPersistenceProvider {
 
     private static final String BULK_SCAN_COLLECTION_NAME = "bulkScans";
 
-    private static boolean isInitialized = false;
     private static final Set<JsonSerializer<?>> serializers = new HashSet<>();
     private static final Set<Module> modules = new HashSet<>();
+    private static final Object registrationLock = new Object();
+    private static volatile boolean registrationClosed = false;
 
     public static void registerSerializer(JsonSerializer<?> serializer) {
-        if (isInitialized) {
-            throw new RuntimeException("Cannot register serializer after initialization");
+        synchronized (registrationLock) {
+            if (registrationClosed) {
+                throw new RuntimeException("Cannot register serializer after initialization");
+            }
+            serializers.add(serializer);
         }
-        serializers.add(serializer);
     }
 
     public static void registerSerializer(JsonSerializer<?>... serializers) {
@@ -68,10 +71,12 @@ public static void registerSerializer(JsonSerializer<?>... serializers) {
     }
 
     public static void registerModule(Module module) {
-        if (isInitialized) {
-            throw new RuntimeException("Cannot register module after initialization");
+        synchronized (registrationLock) {
+            if (registrationClosed) {
+                throw new RuntimeException("Cannot register module after initialization");
+            }
+            modules.add(module);
         }
-        modules.add(module);
     }
 
     public static void registerModule(Module... modules) {
@@ -148,7 +153,9 @@ private static ObjectMapper createMapper() {
      * @param mongoDbDelegate Mongodb command line configuration parameters
      */
     public MongoPersistenceProvider(MongoDbDelegate mongoDbDelegate) {
-        isInitialized = true;
+        synchronized (registrationLock) {
+            registrationClosed = true;
+        }
 
         mapper = createMapper();
         mongoClient = createMongoClient(mongoDbDelegate);