[HER-1706] PersistLoadProcessor and PersistStoreProcessor can't share same BdbModule

* BdbModule.java
    allow Database instance reuse if BdbConfig is identical instance
* PersistProcessor.java
    convert shared BdbConfig for history db to static constant HISTORY_DB_CONFIG
* PersistOnlineProcessor.java
    use HISTORY_DB_CONFIG, don't close possibly-shared DB on stop()
* PrecedenceLoader.java, PreloadedUriPrecedencePolicy.java
    use HISTORY_DB_CONFIG

commons/src/main/java/org/archive/bdb/BdbModule.java

@@ -329,6 +329,12 @@ Serializable, Closeable {
                     "BdbModule not started; as a Lifecycle bean it must not be an inner bean.");
         }
         if (databases.containsKey(name)) {
+            DatabasePlusConfig dpc = databases.get(name);
+            if(dpc.config == config) {
+                // object-identical configs: OK to share DB
+                return dpc.database;
+            }
+            // unshared config object: might be name collision; error
             throw new IllegalStateException("Database already exists: " +name);
         }
         

engine/src/main/java/org/archive/crawler/frontier/precedence/PrecedenceLoader.java

@@ -110,7 +110,7 @@ public class PrecedenceLoader {
         Database historyDB = targetEnv.openDatabase(
                 null,
                 PersistProcessor.URI_HISTORY_DBNAME,
-                PersistProcessor.historyDatabaseConfig().toDatabaseConfig());
+                PersistProcessor.HISTORY_DB_CONFIG.toDatabaseConfig());
         StoredSortedMap historyMap = new StoredSortedMap(historyDB,
                 new StringBinding(), new SerialBinding(classCatalog,
                         Map.class), true);

engine/src/main/java/org/archive/crawler/frontier/precedence/PreloadedUriPrecedencePolicy.java

@@ -79,7 +79,7 @@ implements Lifecycle {
         StoredSortedMap historyMap;
         try {
             StoredClassCatalog classCatalog = bdb.getClassCatalog();
-            BdbModule.BdbConfig dbConfig = PersistProcessor.historyDatabaseConfig();
+            BdbModule.BdbConfig dbConfig = PersistProcessor.HISTORY_DB_CONFIG;
 
             historyDb = bdb.openManagedDatabase(dbName, dbConfig, true);
             historyMap = new StoredSortedMap(historyDb,

modules/src/main/java/org/archive/modules/recrawl/PersistOnlineProcessor.java

@@ -74,7 +74,7 @@ implements Lifecycle {
         StoredSortedMap<String,Map> historyMap;
         try {
             StoredClassCatalog classCatalog = bdb.getClassCatalog();
-            BdbModule.BdbConfig dbConfig = historyDatabaseConfig();
+            BdbModule.BdbConfig dbConfig = HISTORY_DB_CONFIG;
 
             historyDb = bdb.openManagedDatabase(getHistoryDbName(), dbConfig, true);
             historyMap = 
@@ -94,11 +94,10 @@ implements Lifecycle {
     }
 
     public void stop() {
-    	// TODO leave this cleanup to BdbModule?
         if (!isRunning()) {
             return;
         }
-        bdb.closeDatabase(historyDb);
+        // leave other cleanup to BdbModule
         historyDb = null;
     }
 

modules/src/main/java/org/archive/modules/recrawl/PersistProcessor.java

@@ -73,15 +73,13 @@ public abstract class PersistProcessor extends Processor {
     /** name of history Database */
     public static final String URI_HISTORY_DBNAME = "uri_history";
     
-    /**
-     * @return DatabaseConfig for history Database
-     */
-    public static BdbModule.BdbConfig historyDatabaseConfig() {
+    public static final BdbModule.BdbConfig HISTORY_DB_CONFIG;
+    static {
         BdbModule.BdbConfig dbConfig = new BdbModule.BdbConfig();
         dbConfig.setTransactional(false);
         dbConfig.setAllowCreate(true);
         dbConfig.setDeferredWrite(true);
-        return dbConfig;
+        HISTORY_DB_CONFIG = dbConfig;
     }
 
     public PersistProcessor() {
@@ -145,7 +143,7 @@ public abstract class PersistProcessor extends Processor {
         EnhancedEnvironment sourceEnv = setupEnvironment(sourceDir, true);
         StoredClassCatalog sourceClassCatalog = sourceEnv.getClassCatalog();
         Database sourceHistoryDB = sourceEnv.openDatabase(
-                null, URI_HISTORY_DBNAME, historyDatabaseConfig().toDatabaseConfig());
+                null, URI_HISTORY_DBNAME, HISTORY_DB_CONFIG.toDatabaseConfig());
         StoredSortedMap<String,Map> sourceHistoryMap = new StoredSortedMap<String,Map>(sourceHistoryDB,
                 new StringBinding(), new SerialBinding<Map>(sourceClassCatalog,
                         Map.class), true);
@@ -244,7 +242,7 @@ public abstract class PersistProcessor extends Processor {
             targetEnv = setupEnvironment(envFile);
             classCatalog = targetEnv.getClassCatalog();
             historyDB = targetEnv.openDatabase(null, URI_HISTORY_DBNAME, 
-                    historyDatabaseConfig().toDatabaseConfig());
+                    HISTORY_DB_CONFIG.toDatabaseConfig());
             historyMap = new StoredSortedMap<String,Map>(historyDB, 
                     new StringBinding(), new SerialBinding<Map>(classCatalog,
                         Map.class), true);