Migrate Recycler API to log4j-api

log4j-1.2-api/src/main/java/org/apache/log4j/layout/Log4j1SyslogLayout.java

@@ -166,32 +166,36 @@ public String toSerializable(final LogEvent event) {
         // so we generate the message first
         final String message = messageLayout != null ? messageLayout.toSerializable(event)
                 : event.getMessage().getFormattedMessage();
-        final StringBuilder buf = getStringBuilder();
-
-        buf.append('<');
-        buf.append(Priority.getPriority(facility, event.getLevel()));
-        buf.append('>');
-
-        if (header) {
-            final int index = buf.length() + 4;
-            dateConverter.format(event, buf);
-            // RFC 3164 says leading space, not leading zero on days 1-9
-            if (buf.charAt(index) == '0') {
-                buf.setCharAt(index, Chars.SPACE);
+        final StringBuilder buf = acquireStringBuilder();
+
+        try {
+            buf.append('<');
+            buf.append(Priority.getPriority(facility, event.getLevel()));
+            buf.append('>');
+
+            if (header) {
+                final int index = buf.length() + 4;
+                dateConverter.format(event, buf);
+                // RFC 3164 says leading space, not leading zero on days 1-9
+                if (buf.charAt(index) == '0') {
+                    buf.setCharAt(index, Chars.SPACE);
+                }
+
+                buf.append(Chars.SPACE);
+                buf.append(localHostname);
+                buf.append(Chars.SPACE);
             }
 
-            buf.append(Chars.SPACE);
-            buf.append(localHostname);
-            buf.append(Chars.SPACE);
-        }
+            if (facilityPrinting) {
+                buf.append(facility != null ? facility.name().toLowerCase() : "user").append(':');
+            }
 
-        if (facilityPrinting) {
-            buf.append(facility != null ? facility.name().toLowerCase() : "user").append(':');
+            buf.append(message);
+            // TODO: splitting message into 1024 byte chunks?
+            return buf.toString();
+        } finally {
+            releaseStringBuilder(buf);
         }
-
-        buf.append(message);
-        // TODO: splitting message into 1024 byte chunks?
-        return buf.toString();
     }
 
     /**

log4j-1.2-api/src/main/java/org/apache/log4j/layout/Log4j1XmlLayout.java

@@ -16,6 +16,12 @@
  */
 package org.apache.log4j.layout;
 
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.Objects;
+
 import org.apache.logging.log4j.core.Layout;
 import org.apache.logging.log4j.core.LogEvent;
 import org.apache.logging.log4j.core.layout.AbstractStringLayout;
@@ -28,12 +34,6 @@
 import org.apache.logging.log4j.util.ReadOnlyStringMap;
 import org.apache.logging.log4j.util.Strings;
 
-import java.io.PrintWriter;
-import java.io.StringWriter;
-import java.nio.charset.StandardCharsets;
-import java.util.List;
-import java.util.Objects;
-
 /**
  * Port of XMLLayout in Log4j 1.x. Provided for compatibility with existing Log4j 1 configurations.
  *
@@ -75,16 +75,24 @@ public boolean isProperties() {
 
     @Override
     public void encode(final LogEvent event, final ByteBufferDestination destination) {
-        final StringBuilder text = getStringBuilder();
-        formatTo(event, text);
-        getStringBuilderEncoder().encode(text, destination);
+        final StringBuilder text = acquireStringBuilder();
+        try {
+            formatTo(event, text);
+            getStringBuilderEncoder().encode(text, destination);
+        } finally {
+            releaseStringBuilder(text);
+        }
     }
 
     @Override
     public String toSerializable(final LogEvent event) {
-        final StringBuilder text = getStringBuilder();
-        formatTo(event, text);
-        return text.toString();
+        final StringBuilder text = acquireStringBuilder();
+        try {
+            formatTo(event, text);
+            return text.toString();
+        } finally {
+            releaseStringBuilder(text);
+        }
     }
 
     private void formatTo(final LogEvent event, final StringBuilder buf) {

log4j-api-test/src/test/java/org/apache/logging/log4j/message/ReusableMessageFactoryTest.java

@@ -16,6 +16,8 @@
  */
 package org.apache.logging.log4j.message;
 
+import org.apache.logging.log4j.spi.ThreadLocalRecyclerFactory;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -25,35 +27,39 @@
  */
 public class ReusableMessageFactoryTest {
 
+    private ReusableMessageFactory factory;
+
+    @BeforeEach
+    void setUp() {
+        factory = new ReusableMessageFactory(ThreadLocalRecyclerFactory.getInstance());
+    }
+
     @Test
     public void testCreateEventReturnsDifferentInstanceIfNotReleased() throws Exception {
-        final ReusableMessageFactory factory = new ReusableMessageFactory();
         final Message message1 = factory.newMessage("text, p0={} p1={} p2={} p3={}", 1, 2, 3, 4);
         final Message message2 = factory.newMessage("text, p0={} p1={} p2={} p3={}", 9, 8, 7, 6);
         assertNotSame(message1, message2);
-        ReusableMessageFactory.release(message1);
-        ReusableMessageFactory.release(message2);
+        factory.recycle(message1);
+        factory.recycle(message2);
     }
 
     @Test
     public void testCreateEventReturnsSameInstance() throws Exception {
-        final ReusableMessageFactory factory = new ReusableMessageFactory();
         final Message message1 = factory.newMessage("text, p0={} p1={} p2={} p3={}", 1, 2, 3, 4);
 
-        ReusableMessageFactory.release(message1);
+        factory.recycle(message1);
         final Message message2 = factory.newMessage("text, p0={} p1={} p2={} p3={}", 9, 8, 7, 6);
         assertSame(message1, message2);
 
-        ReusableMessageFactory.release(message2);
+        factory.recycle(message2);
         final Message message3 = factory.newMessage("text, AAA={} BBB={} p2={} p3={}", 9, 8, 7, 6);
         assertSame(message2, message3);
-        ReusableMessageFactory.release(message3);
+        factory.recycle(message3);
     }
 
     private void assertReusableParameterizeMessage(final Message message, final String txt, final Object[] params) {
         assertTrue(message instanceof ReusableParameterizedMessage);
         final ReusableParameterizedMessage msg = (ReusableParameterizedMessage) message;
-        assertTrue(msg.reserved, "reserved");
 
         assertEquals(txt, msg.getFormat());
         assertEquals(msg.getParameterCount(), params.length, "count");
@@ -65,7 +71,6 @@ private void assertReusableParameterizeMessage(final Message message, final Stri
 
     @Test
     public void testCreateEventOverwritesFields() throws Exception {
-        final ReusableMessageFactory factory = new ReusableMessageFactory();
         final Message message1 = factory.newMessage("text, p0={} p1={} p2={} p3={}", 1, 2, 3, 4);
         assertReusableParameterizeMessage(message1, "text, p0={} p1={} p2={} p3={}", new Object[]{
                 new Integer(1), //
@@ -74,7 +79,7 @@ public void testCreateEventOverwritesFields() throws Exception {
                 new Integer(4), //
         });
 
-        ReusableMessageFactory.release(message1);
+        factory.recycle(message1);
         final Message message2 = factory.newMessage("other, A={} B={} C={} D={}", 1, 2, 3, 4);
         assertReusableParameterizeMessage(message1, "other, A={} B={} C={} D={}", new Object[]{
                 new Integer(1), //
@@ -83,12 +88,11 @@ public void testCreateEventOverwritesFields() throws Exception {
                 new Integer(4), //
         });
         assertSame(message1, message2);
-        ReusableMessageFactory.release(message2);
+        factory.recycle(message2);
     }
 
     @Test
     public void testCreateEventReturnsThreadLocalInstance() throws Exception {
-        final ReusableMessageFactory factory = new ReusableMessageFactory();
         final Message[] message1 = new Message[1];
         final Message[] message2 = new Message[1];
         final Thread t1 = new Thread("THREAD 1") {
@@ -123,8 +127,8 @@ public void run() {
                 new Integer(3), //
                 new Integer(4), //
         });
-        ReusableMessageFactory.release(message1[0]);
-        ReusableMessageFactory.release(message2[0]);
+        factory.recycle(message1[0]);
+        factory.recycle(message2[0]);
     }
 
 }

log4j-api-test/src/test/java/org/apache/logging/log4j/spi/ThreadLocalRecyclerFactoryTest.java

@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF 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.apache.logging.log4j.spi;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class ThreadLocalRecyclerFactoryTest {
+    @Test
+    void nestedAcquiresDoNotInterfere() {
+        final Recycler<AtomicInteger> r = ThreadLocalRecyclerFactory.getInstance()
+                .create(AtomicInteger::new, i -> i.set(0));
+        final var recycler = (ThreadLocalRecyclerFactory.ThreadLocalRecycler<AtomicInteger>) r;
+
+        assertThat(recycler.getQueue()).isEmpty();
+        final AtomicInteger first = recycler.acquire();
+        assertThat(recycler.getQueue()).isEmpty();
+        final AtomicInteger second = recycler.acquire();
+        assertThat(recycler.getQueue()).isEmpty();
+        first.set(1);
+        second.set(2);
+        final AtomicInteger third = recycler.acquire();
+        assertThat(recycler.getQueue()).isEmpty();
+        assertThat(third.get()).isEqualTo(0);
+        assertThat(first.get()).isEqualTo(1);
+        assertThat(second.get()).isEqualTo(2);
+        recycler.release(first);
+        assertThat(recycler.getQueue()).hasSize(1);
+        recycler.release(second);
+        assertThat(recycler.getQueue()).hasSize(2);
+        recycler.release(third);
+        assertThat(recycler.getQueue()).hasSize(3);
+    }
+}

log4j-api/pom.xml

@@ -43,6 +43,11 @@
       <artifactId>org.osgi.resource</artifactId>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>org.jctools</groupId>
+      <artifactId>jctools-core</artifactId>
+      <optional>true</optional>
+    </dependency>
   </dependencies>
   <build>
     <plugins>
@@ -52,10 +57,6 @@
         <configuration>
           <instructions>
             <Export-Package>org.apache.logging.log4j.*</Export-Package>
-            <Import-Package>
-              sun.reflect;resolution:=optional,
-              *
-            </Import-Package>
             <Bundle-Activator>org.apache.logging.log4j.util.Activator</Bundle-Activator>
             <_fixupmessages>"Classes found in the wrong directory";is:=warning</_fixupmessages>
           </instructions>

log4j-api/src/main/java/module-info.java

@@ -38,8 +38,12 @@
     exports org.apache.logging.log4j.status;
     exports org.apache.logging.log4j.util;
 
+    // optional support for formatting SQL date/time classes in messages properly
     requires static java.sql;
+    // optional support for running in an OSGi environment
     requires static org.osgi.framework;
+    // optional support for using JCTools in a Recycler
+    requires static org.jctools.core;
     uses org.apache.logging.log4j.spi.Provider;
     uses PropertySource;
     uses org.apache.logging.log4j.message.ThreadDumpMessage.ThreadInfoFactory;

log4j-api/src/main/java/org/apache/logging/log4j/message/MessageFactory.java

@@ -18,6 +18,8 @@
 
 /**
  * Creates messages. Implementations can provide different message format syntaxes.
+ * If messages created by an implementation are reusable, then the {@link #recycle(Message)} method must
+ * be implemented and consistently used for returning objects to be reused.
  *
  * @see ParameterizedMessageFactory
  * @see StringFormatterMessageFactory
@@ -236,4 +238,16 @@ default Message newMessage(final String message, final Object p0, final Object p
                                final Object p6, final Object p7, final Object p8, final Object p9) {
         return newMessage(message, new Object[] { p0, p1, p2, p3, p4, p5, p6, p7, p8, p9 });
     }
+
+    /**
+     * Recycles a message back for potential reuse or cleanup.
+     *
+     * @since 3.0.0
+     * @see org.apache.logging.log4j.spi.Recycler
+     */
+    default void recycle(Message message) {
+        if (message instanceof ReusableMessage) {
+            ((ReusableMessage) message).clear();
+        }
+    }
 }