improvements to SLF4J-515

Signed-off-by: Ceki Gulcu <ceki@qos.ch>

slf4j-simple/src/main/java/org/slf4j/impl/SimpleLogger.java

@@ -26,8 +26,6 @@
 
 import java.io.PrintStream;
 import java.util.Date;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.locks.ReentrantLock;
 
 import org.slf4j.Logger;
 import org.slf4j.event.LoggingEvent;
@@ -314,6 +312,13 @@ protected String renderLevel(int level) {
         throw new IllegalStateException("Unrecognized level [" + level + "]");
     }
 
+    /**
+     * To avoid intermingling of log messages and associated stack traces, the two
+     * operations are done in a synchronized block.
+     * 
+     * @param buf
+     * @param t
+     */
     void write(StringBuilder buf, Throwable t) {
         PrintStream targetStream = CONFIG_PARAMS.outputChoice.getTargetPrintStream();
 

slf4j-simple/src/test/java/org/slf4j/simple/multiThreadedExecution/MultithereadedExecutionTest.java

@@ -40,6 +40,8 @@
 public class MultithereadedExecutionTest {
 
     private static int THREAD_COUNT = 2;
+    private static long TEST_DURATION_IN_MILLIS = 100;
+
     private Thread[] threads = new Thread[THREAD_COUNT];
 
     private final PrintStream oldOut = System.out;
@@ -69,7 +71,7 @@ public void test() throws Throwable {
         threads[1] = new Thread(other);
         threads[0].start();
         threads[1].start();
-        Thread.sleep(100);
+        Thread.sleep(TEST_DURATION_IN_MILLIS);
         signal = true;
         threads[0].join();
         threads[1].join();
@@ -86,10 +88,9 @@ public void test() throws Throwable {
 
     class WithException implements Runnable {
 
-        Throwable throwable;
+        volatile Throwable throwable;
         Logger logger = LoggerFactory.getLogger(WithException.class);
 
-        @Override
         public void run() { 
             int i = 0;
 
@@ -108,10 +109,9 @@ public void run() {
     }
 
     class Other implements Runnable {
-        Throwable throwable;
+        volatile Throwable throwable;
         Logger logger = LoggerFactory.getLogger(Other.class);
 
-        @Override
         public void run() {
             int i = 0;
             while (!signal) {
@@ -125,5 +125,4 @@ public void run() {
             }
         }
     }
-
 }

slf4j-simple/src/test/java/org/slf4j/simple/multiThreadedExecution/StateCheckingPrintStream.java

@@ -25,20 +25,20 @@
 package org.slf4j.simple.multiThreadedExecution;
 
 import java.io.PrintStream;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
 import java.util.regex.Pattern;
 
+/**
+ * This PrintStream checks that output lines are in an expected order.
+ * 
+ * @author ceki
+ */
 public class StateCheckingPrintStream extends PrintStream {
 
     enum State {
         INITIAL, UNKNOWN, HELLO, THROWABLE, AT1, AT2, OTHER;
     }
 
-    List<String> stringList = Collections.synchronizedList(new ArrayList<String>());
-
-    State currentState = State.INITIAL;
+    volatile State currentState = State.INITIAL;
 
     public StateCheckingPrintStream(PrintStream ps) {
         super(ps);
@@ -57,6 +57,7 @@ public void println(String s) {
             break;
 
         case UNKNOWN:
+            // ignore garbage
             currentState = next;
             break;
 
@@ -98,8 +99,6 @@ public void println(String s) {
         default:
             throw new IllegalStateException("Unreachable code");
         }
-
-        stringList.add(s);
     }
 
     private IllegalStateException badState(String s, State currentState2, State next) {