* Logging:

- Limit buffer size; block and wakeup writer when full
      - Limit errors written to system log
      - Add method to force a log below the current level

core/java/src/net/i2p/util/Log.java

@@ -117,6 +117,17 @@ public class Log {
         }
     }
 
+    /**
+     *  Always log this messge with the given priority, ignoring current minimum priority level.
+     *  This allows an INFO message about changing port numbers, for example, to always be logged.
+     *  @since 0.8.2
+     */
+    public void logAlways(int priority, String msg) {
+            _manager.addRecord(new LogRecord(_class, _name, 
+                                             Thread.currentThread().getName(), priority,
+                                             msg, null));
+    }
+
     public void debug(String msg) {
         log(DEBUG, msg);
     }

core/java/src/net/i2p/util/LogManager.java

@@ -23,6 +23,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
+import java.util.Queue;
 import java.util.Set;
 import java.util.TimeZone;
 import java.util.TreeMap;
@@ -78,6 +79,9 @@ public class LogManager {
 
     /** the config file */
     private File _locationFile;
+
+    /** max to LogRecords to buffer in memory before we start blocking */
+    private static final int MAX_BUFFER = 1024;
     /** Ordered list of LogRecord elements that have not been written out yet */
     private final LinkedBlockingQueue<LogRecord> _records;
     /** List of explicit overrides of log levels (LogLimit objects) */
@@ -119,7 +123,7 @@ public class LogManager {
     public LogManager(I2PAppContext context) {
         _displayOnScreen = true;
         _alreadyNoticedMissingConfig = false;
-        _records = new LinkedBlockingQueue();
+        _records = new LinkedBlockingQueue(MAX_BUFFER);
         _limits = new ConcurrentHashSet();
         _logs = new ConcurrentHashMap(128);
         _defaultLimit = Log.ERROR;
@@ -221,25 +225,26 @@ public class LogManager {
     }
 
     /**
-     * Used by Log to add records to the queue
-     *
+     * Used by Log to add records to the queue.
+     * This is generally nonblocking and unsyncrhonized but may block when under
+     * massive logging load as a way of throttling logging threads.
      */
     void addRecord(LogRecord record) {
         if ((!_context.isRouterContext()) && _writer == null)
             startLogWriter();
 
-        _records.offer(record);
-      /**** don't burden the logging thread with counting
-        int numRecords = _records.size();
-        
-        if (numRecords > 100) {
+        boolean success = _records.offer(record);
+        if (!success) {
             // the writer waits 10 seconds *or* until we tell them to wake up
             // before rereading the config and writing out any log messages
             synchronized (_writer) {
                 _writer.notifyAll();
             }
+            // block as a way of slowing down out-of-control loggers (a little)
+            try {
+                _records.put(record);
+            } catch (InterruptedException ie) {}
         }
-       ****/
     }
     
     /**
@@ -605,10 +610,13 @@ public class LogManager {
         return buf.toString();
     }
 
-    List<LogRecord> _removeAll() {
-        List<LogRecord> vals = new LinkedList();
-        _records.drainTo(vals);
-        return vals;
+    /**
+     *  Zero-copy.
+     *  For the LogWriter
+     *  @since 0.8.2
+     */
+    Queue<LogRecord> getQueue() {
+        return _records;
     }
 
     public char[] getFormat() {

core/java/src/net/i2p/util/LogWriter.java

@@ -15,7 +15,7 @@ import java.io.IOException;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.Writer;
-import java.util.List;
+import java.util.Queue;
 
 import net.i2p.I2PAppContext;
 
@@ -38,6 +38,8 @@ class LogWriter implements Runnable {
     private LogManager _manager;
 
     private boolean _write;
+    private static final int MAX_DISKFULL_MESSAGES = 8;
+    private int _diskFullMessageCount;
     
     private LogWriter() { // nop
     }
@@ -61,7 +63,7 @@ class LogWriter implements Runnable {
             }
             //System.err.println("Done writing");
         } catch (Exception e) {
-            System.err.println("Error writing the logs: " + e.getMessage());
+            System.err.println("Error writing the log: " + e);
             e.printStackTrace();
         }
         closeFile();
@@ -70,16 +72,19 @@ class LogWriter implements Runnable {
     public void flushRecords() { flushRecords(true); }
     public void flushRecords(boolean shouldWait) {
         try {
-            List<LogRecord> records = _manager._removeAll();
+            // zero copy, drain the manager queue directly
+            Queue<LogRecord> records = _manager.getQueue();
             if (records == null) return;
             if (!records.isEmpty()) {
-                for (LogRecord rec : records) {
+                LogRecord rec;
+                while ((rec = records.poll()) != null) {
                     writeRecord(rec);
                 }
                 try {
                     _currentOut.flush();
                 } catch (IOException ioe) {
-                    System.err.println("Error writing the router log");
+                    if (++_diskFullMessageCount < MAX_DISKFULL_MESSAGES)
+                        System.err.println("Error writing the router log - disk full? " + ioe);
                 }
             }
         } catch (Throwable t) {
@@ -138,6 +143,7 @@ class LogWriter implements Runnable {
         } catch (Throwable t) {
             if (!_write)
                 return;
+            if (++_diskFullMessageCount < MAX_DISKFULL_MESSAGES)
                 System.err.println("Error writing log, disk full? " + t);
             //t.printStackTrace();
         }