more rapidly release refs for finished CrawlURIs

* UriProcessingFormatter, Preformatter, GenerationFileHandler
    improve preformat-outside-synchronized optimization so that the LogRecord/CrawlURI doesn't linger until next displaces it
* CrawlURI
    (processingCleanup) null more of last-processing-run collected values

engine/src/main/java/org/archive/crawler/io/Preformatter.java

@@ -0,0 +1,32 @@
+/*
+ *  This file is part of the Heritrix web crawler (crawler.archive.org).
+ *
+ *  Licensed to the Internet Archive (IA) by one or more individual 
+ *  contributors. 
+ *
+ *  The IA licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.archive.crawler.io;
+
+import java.util.logging.LogRecord;
+
+/**
+ * Interface indicating a logging Formatter can preformat a record (outside
+ * the standard-implementation synchronized block) and cache it, returning it
+ * for the next request for formatting from the same thread. 
+ * @contributor gojomo
+ */
+public interface Preformatter {
+    public void preformat(LogRecord record); 
+    public void clear(); 
+}

engine/src/main/java/org/archive/crawler/io/UriProcessingFormatter.java

@@ -34,7 +34,7 @@ import org.archive.util.MimetypeUtils;
  * @author gojomo
  */
 public class UriProcessingFormatter
-extends Formatter implements CoreAttributeConstants {
+extends Formatter implements Preformatter, CoreAttributeConstants {
     private final static String NA = "-";
     /**
      * Guess at line length (URIs are assumed avg. of 128 bytes).
@@ -57,7 +57,6 @@ extends Formatter implements CoreAttributeConstants {
             }
     };
     
-    protected final ThreadLocal<LogRecord> cachedRecord = new ThreadLocal<LogRecord>(); 
     protected final ThreadLocal<String> cachedFormat = new ThreadLocal<String>();
     protected boolean logExtraInfo; 
     
@@ -66,7 +65,7 @@ extends Formatter implements CoreAttributeConstants {
     }
 
     public String format(LogRecord lr) {
-        if(lr==cachedRecord.get()) {
+        if(cachedFormat.get()!=null) {
             return cachedFormat.get();
         }
         CrawlURI curi = (CrawlURI)lr.getParameters()[0];
@@ -153,10 +152,7 @@ extends Formatter implements CoreAttributeConstants {
         }
         
         buffer.append("\n");
-        cachedRecord.set(lr); 
-        String formatted = buffer.toString(); 
-        cachedFormat.set(formatted);
-        return formatted;
+        return buffer.toString(); 
     }
 
     /**
@@ -166,6 +162,16 @@ extends Formatter implements CoreAttributeConstants {
     protected String checkForNull(String str) {
         return (str == null || str.length() <= 0)? NA: str;
     }
+
+    @Override
+    public void clear() {
+        cachedFormat.set(null); 
+    }
+
+    @Override
+    public void preformat(LogRecord record) {
+        cachedFormat.set(format(record));
+    }
 }