fixing SLF4J-515

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

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

@@ -26,6 +26,8 @@
 
 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;
@@ -159,6 +161,9 @@ public class SimpleLogger extends MarkerIgnoringBase {
     private static boolean INITIALIZED = false;
     static SimpleLoggerConfiguration CONFIG_PARAMS = null;
 
+    private static final long MAX_TRY_LOCK_DURATION = 200L;
+    static ReentrantLock lock = new ReentrantLock();
+
     static void lazyInit() {
         if (INITIALIZED) {
             return;
@@ -315,9 +320,15 @@ protected String renderLevel(int level) {
     void write(StringBuilder buf, Throwable t) {
         PrintStream targetStream = CONFIG_PARAMS.outputChoice.getTargetPrintStream();
 
-        targetStream.println(buf.toString());
-        writeThrowable(t, targetStream);
-        targetStream.flush();
+        try {
+            lock.tryLock(MAX_TRY_LOCK_DURATION, TimeUnit.MILLISECONDS);
+            targetStream.println(buf.toString());
+            writeThrowable(t, targetStream);
+            targetStream.flush();
+        } catch (InterruptedException e) {
+        } finally {
+            lock.unlock();
+        }
     }
 
     protected void writeThrowable(Throwable t, PrintStream targetStream) {

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

@@ -0,0 +1,129 @@
+/**
+ * Copyright (c) 2004-2021 QOS.ch
+ * All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to  deal in  the Software without  restriction, including
+ * without limitation  the rights to  use, copy, modify,  merge, publish,
+ * distribute,  sublicense, and/or sell  copies of  the Software,  and to
+ * permit persons to whom the Software  is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The  above  copyright  notice  and  this permission  notice  shall  be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
+ * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
+ * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+package org.slf4j.simple.multiThreadedExecution;
+
+import java.io.PrintStream;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Tests that output in multi-threaded environments is not mingled.
+ * 
+ * See also https://jira.qos.ch/browse/SLF4J-515
+ */
+public class MultithereadedExecutionTest {
+
+    private static int THREAD_COUNT = 2;
+    private Thread[] threads = new Thread[THREAD_COUNT];
+
+    private final PrintStream oldOut = System.out;
+    StateCheckingPrintStream scps = new StateCheckingPrintStream(oldOut);
+
+    volatile boolean signal = false;
+
+    @Before
+    public void setup() {
+        System.setErr(scps);
+        // System.setProperty(SimpleLogger.LOG_FILE_KEY, "System.err");
+        // LoggerFactoryFriend.reset();
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        // LoggerFactoryFriend.reset();
+        // System.clearProperty(SimpleLogger.LOG_FILE_KEY);
+        System.setErr(oldOut);
+    }
+
+    @Test
+    public void test() throws Throwable {
+        WithException withException = new WithException();
+        Other other = new Other();
+        threads[0] = new Thread(withException);
+        threads[1] = new Thread(other);
+        threads[0].start();
+        threads[1].start();
+        Thread.sleep(100);
+        signal = true;
+        threads[0].join();
+        threads[1].join();
+
+        if (withException.throwable != null) {
+            throw withException.throwable;
+        }
+
+        if (other.throwable != null) {
+            throw other.throwable;
+        }
+
+    }
+
+    class WithException implements Runnable {
+
+        Throwable throwable;
+        Logger logger = LoggerFactory.getLogger(WithException.class);
+
+        @Override
+        public void run() { // TODO Auto-generated method stub
+            int i = 0;
+
+            while (!signal) {
+                try {
+                    logger.info("Hello {}", i, new Throwable("i=" + i));
+                    i++;
+                } catch (Throwable t) {
+                    throwable = t;
+                    MultithereadedExecutionTest.this.signal = true;
+                    return;
+                }
+            }
+
+        }
+    }
+
+    class Other implements Runnable {
+        Throwable throwable;
+        Logger logger = LoggerFactory.getLogger(Other.class);
+
+        @Override
+        public void run() {
+            int i = 0;
+            while (!signal) {
+                try {
+                    logger.info("Other {}", i++);
+                } catch (Throwable t) {
+                    throwable = t;
+                    MultithereadedExecutionTest.this.signal = true;
+                    return;
+                }
+            }
+        }
+    }
+
+}

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

@@ -0,0 +1,144 @@
+/**
+ * Copyright (c) 2004-2021 QOS.ch
+ * All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to  deal in  the Software without  restriction, including
+ * without limitation  the rights to  use, copy, modify,  merge, publish,
+ * distribute,  sublicense, and/or sell  copies of  the Software,  and to
+ * permit persons to whom the Software  is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The  above  copyright  notice  and  this permission  notice  shall  be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
+ * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
+ * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+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;
+
+public class StateCheckingPrintStream extends PrintStream {
+
+    enum State {
+        INITIAL, UNKNOWN, HELLO, THROWABLE, AT1, AT2, OTHER;
+    }
+
+    PrintStream other;
+
+    List<String> stringList = Collections.synchronizedList(new ArrayList<String>());
+
+    State currentState = State.INITIAL;
+
+    public StateCheckingPrintStream(PrintStream ps) {
+        super(ps);
+    }
+
+    public void print(String s) {
+    }
+
+    public void println(String s) {
+
+        State next = computeState(s);
+        //System.out.println(next + " " + s);
+        switch (currentState) {
+        case INITIAL:
+            currentState = next;
+            break;
+
+        case UNKNOWN:
+            currentState = next;
+            break;
+
+        case OTHER:
+            if (next == State.UNKNOWN) {
+                currentState = State.UNKNOWN;
+                return;
+            }
+
+            if (next != State.OTHER && next != State.HELLO) {
+                throw badState(s, currentState, next);
+            }
+            currentState = next;
+            break;
+
+        case HELLO:
+            if (next != State.THROWABLE) {
+                throw badState(s, currentState, next);
+            } 
+            currentState = next;
+            break;
+        case THROWABLE:
+            if (next != State.AT1) {
+                throw badState(s, currentState, next);
+            }
+            currentState = next;
+            break;
+
+        case AT1:
+            if (next != State.AT2) {
+                throw badState(s, currentState, next);
+            }
+            currentState = next;
+            break;
+
+        case AT2:
+            currentState = next;
+            break;
+        default:
+            throw new IllegalStateException("Unreachable code");
+        }
+
+        stringList.add(s);
+    }
+
+    private IllegalStateException badState(String s, State currentState2, State next) {
+        return new IllegalStateException("Unexpected state " + next + " for current state " + currentState2 + " for " + s);
+
+    }
+
+    String OTHER_PATTERN_STR = ".*Other \\d{1,5}";
+    String HELLO_PATTERN_STR = ".*Hello \\d{1,5}";
+    String THROWABLE_PATTERN_STR = "java.lang.Throwable: i=\\d{1,5}";
+    String AT1_PATTERN_STR = "\\s*at " + this.getClass().getPackage().getName() + ".*";
+    String AT2_PATTERN_STR = "\\s*at " + ".*Thread.java.*";
+
+    Pattern PATTERN_OTHER = Pattern.compile(OTHER_PATTERN_STR);
+    Pattern PATTERN_HELLO = Pattern.compile(HELLO_PATTERN_STR);
+    Pattern PATTERN_THROWABLE = Pattern.compile(THROWABLE_PATTERN_STR);
+    Pattern PATTERN_AT1 = Pattern.compile(AT1_PATTERN_STR);
+    Pattern PATTERN_AT2 = Pattern.compile(AT2_PATTERN_STR);
+
+    private State computeState(String s) {
+
+        if (PATTERN_OTHER.matcher(s).matches()) {
+            return State.OTHER;
+        } else if (PATTERN_HELLO.matcher(s).matches()) {
+            return State.HELLO;
+        } else if (PATTERN_THROWABLE.matcher(s).matches()) {
+            return State.THROWABLE;
+        } else if (PATTERN_AT1.matcher(s).matches()) {
+            return State.AT1;
+        } else if (PATTERN_AT2.matcher(s).matches()) {
+            return State.AT2;
+        } else {
+            return State.UNKNOWN;
+        }
+    }
+
+    public void println(Object o) {
+        println(o.toString());
+    }
+}