Minor refactoring and improving code styles

README.md

@@ -32,7 +32,7 @@ implementation:
 ```java
 public class MyCrawler extends WebCrawler {
 
-    private final static Pattern FILTERS = Pattern.compile(".*(\\.(css|js|gif|jpe?g"
+    private final static Pattern FILTERS = Pattern.compile(".*(\\.(css|js|gif|jpg"
                                                            + "|png|mp3|mp3|zip|gz))$");
 
     /**

src/main/java/edu/uci/ics/crawler4j/fetcher/PageFetcher.java

@@ -69,7 +69,6 @@
  * @author Yasser Ganjisaffar
  */
 public class PageFetcher extends Configurable {
-
   protected static final Logger logger = LoggerFactory.getLogger(PageFetcher.class);
 
   protected PoolingHttpClientConnectionManager connectionManager;
@@ -240,6 +239,15 @@ public PageFetchResult fetchPage(WebURL webUrl)
         // Checking maximum size
         if (fetchResult.getEntity() != null) {
           long size = fetchResult.getEntity().getContentLength();
+          if (size == -1) {
+            Header length = response.getLastHeader("Content-Length");
+            if (length == null) {
+              length = response.getLastHeader("Content-length");
+            }
+            if (length != null) {
+              size = Integer.parseInt(length.getValue());
+            }
+          }
           if (size > config.getMaxDownloadSize()) {
             throw new PageBiggerThanMaxSizeException(size);
           }

src/main/java/edu/uci/ics/crawler4j/frontier/Counters.java

@@ -95,7 +95,11 @@ public Counters(Environment env, CrawlConfig config) {
 
   public long getValue(String name) {
     synchronized (mutex) {
-      return (counterValues.get(name) == null) ? 0 : counterValues.get(name);
+      Long value = counterValues.get(name);
+      if (value == null) {
+        return 0;
+      }
+      return value;
     }
   }
 

src/main/java/edu/uci/ics/crawler4j/frontier/DocIDServer.java

@@ -36,31 +36,29 @@
  */
 
 public class DocIDServer extends Configurable {
+  private static final Logger logger = LoggerFactory.getLogger(DocIDServer.class);
 
+  private final Database docIDsDB;
   private static final String DATABASE_NAME = "DocIDs";
-  protected static final Logger logger = LoggerFactory.getLogger(DocIDServer.class);
 
-  protected Database docIDsDB = null;
+  private final Object mutex = new Object();
 
-  protected final Object mutex = new Object();
-
-  protected int lastDocID;
+  private int lastDocID;
 
   public DocIDServer(Environment env, CrawlConfig config) {
     super(config);
     DatabaseConfig dbConfig = new DatabaseConfig();
     dbConfig.setAllowCreate(true);
     dbConfig.setTransactional(config.isResumableCrawling());
     dbConfig.setDeferredWrite(!config.isResumableCrawling());
+    lastDocID = 0;
     docIDsDB = env.openDatabase(null, DATABASE_NAME, dbConfig);
     if (config.isResumableCrawling()) {
       int docCount = getDocCount();
       if (docCount > 0) {
         logger.info("Loaded {} URLs that had been detected in previous crawl.", docCount);
         lastDocID = docCount;
       }
-    } else {
-      lastDocID = 0;
     }
   }
 
@@ -72,46 +70,41 @@ public DocIDServer(Environment env, CrawlConfig config) {
    */
   public int getDocId(String url) {
     synchronized (mutex) {
-      int docID = -1;
-
-      if (docIDsDB != null) {
-        OperationStatus result = null;
-        DatabaseEntry value = new DatabaseEntry();
-        try {
-          DatabaseEntry key = new DatabaseEntry(url.getBytes());
-          result = docIDsDB.get(null, key, value, null);
+      OperationStatus result = null;
+      DatabaseEntry value = new DatabaseEntry();
+      try {
+        DatabaseEntry key = new DatabaseEntry(url.getBytes());
+        result = docIDsDB.get(null, key, value, null);
 
-        } catch (Exception e) {
-          logger.error("Exception thrown while getting DocID", e);
-        }
+      } catch (Exception e) {
+        logger.error("Exception thrown while getting DocID", e);
+        return -1;
+      }
 
-        if ((result != null) && (result == OperationStatus.SUCCESS) && (value.getData().length > 0)) {
-          docID = Util.byteArray2Int(value.getData());
-        }
+      if ((result == OperationStatus.SUCCESS) && (value.getData().length > 0)) {
+        return Util.byteArray2Int(value.getData());
       }
 
-      return docID;
+      return -1;
     }
   }
 
   public int getNewDocID(String url) {
-
     synchronized (mutex) {
-      int docID = -1;
       try {
         // Make sure that we have not already assigned a docid for this URL
-        docID = getDocId(url);
-
-        if (docID <= 0) {
-          lastDocID++;
-          docIDsDB.put(null, new DatabaseEntry(url.getBytes()), new DatabaseEntry(Util.int2ByteArray(lastDocID)));
-          docID = lastDocID;
+        int docID = getDocId(url);
+        if (docID > 0) {
+          return docID;
         }
+
+        ++lastDocID;
+        docIDsDB.put(null, new DatabaseEntry(url.getBytes()), new DatabaseEntry(Util.int2ByteArray(lastDocID)));
+        return lastDocID;
       } catch (Exception e) {
         logger.error("Exception thrown while getting new DocID", e);
+        return -1;
       }
-
-      return docID;
     }
   }
 
@@ -140,14 +133,12 @@ public boolean isSeenBefore(String url) {
   }
 
   public final int getDocCount() {
-    int count = -1;
-
     try {
-      count = (int) docIDsDB.count();
+      return (int) docIDsDB.count();
     } catch (DatabaseException e) {
       logger.error("Exception thrown while getting DOC Count", e);
+      return -1;
     }
-    return count;
   }
 
   public void close() {

src/main/java/edu/uci/ics/crawler4j/frontier/Frontier.java

@@ -34,8 +34,8 @@
  */
 
 public class Frontier extends Configurable {
-
   protected static final Logger logger = LoggerFactory.getLogger(Frontier.class);
+
   private static final String DATABASE_NAME = "PendingURLsDB";
   protected WorkQueues workQueues;
 

src/main/java/edu/uci/ics/crawler4j/frontier/InProcessPagesDB.java

@@ -23,7 +23,6 @@
 
 import com.sleepycat.je.Cursor;
 import com.sleepycat.je.DatabaseEntry;
-import com.sleepycat.je.DatabaseException;
 import com.sleepycat.je.Environment;
 import com.sleepycat.je.OperationStatus;
 import com.sleepycat.je.Transaction;
@@ -38,9 +37,10 @@
  * @author Yasser Ganjisaffar
  */
 public class InProcessPagesDB extends WorkQueues {
-
   private static final Logger logger = LoggerFactory.getLogger(InProcessPagesDB.class);
+
   private static final String DATABASE_NAME = "InProcessPagesDB";
+
   public InProcessPagesDB(Environment env) {
     super(env, DATABASE_NAME, true);
     long docCount = getLength();
@@ -51,37 +51,21 @@ public InProcessPagesDB(Environment env) {
 
   public boolean removeURL(WebURL webUrl) {
     synchronized (mutex) {
-      try {
-        DatabaseEntry key = getDatabaseEntryKey(webUrl);
-        Cursor cursor = null;
-        DatabaseEntry value = new DatabaseEntry();
-        Transaction txn = env.beginTransaction(null, null);
-        try {
-          cursor = urlsDB.openCursor(txn, null);
-          OperationStatus result = cursor.getSearchKey(key, value, null);
+      DatabaseEntry key = getDatabaseEntryKey(webUrl);
+      DatabaseEntry value = new DatabaseEntry();
+      Transaction txn = beginTransaction();
+      try (Cursor cursor = openCursor(txn)) {
+        OperationStatus result = cursor.getSearchKey(key, value, null);
 
+        if (result == OperationStatus.SUCCESS) {
+          result = cursor.delete();
           if (result == OperationStatus.SUCCESS) {
-            result = cursor.delete();
-            if (result == OperationStatus.SUCCESS) {
-              return true;
-            }
-          }
-        } catch (DatabaseException e) {
-          if (txn != null) {
-            txn.abort();
-            txn = null;
-          }
-          throw e;
-        } finally {
-          if (cursor != null) {
-            cursor.close();
-          }
-          if (txn != null) {
-            txn.commit();
+            return true;
           }
         }
-      } catch (Exception e) {
-        logger.error("Error while manipulating the DB of links from previous crawls", e);
+      }
+      if (txn != null) {
+        txn.commit();
       }
     }
     return false;