[JENKINS-54566] finalize vs. flush

src/main/java/org/jenkinsci/plugins/workflow/log/BufferedBuildListener.java

@@ -74,7 +74,7 @@ private static final class Replacement implements SerializableOnlyOverRemoting {
         }
 
         private Object readResolve() throws IOException {
-            return new BufferedBuildListener(new DelayBufferedOutputStream(ros, tuning));
+            return new BufferedBuildListener(new GCFlushedOutputStream(new DelayBufferedOutputStream(ros, tuning)));
         }
 
     }

src/main/java/org/jenkinsci/plugins/workflow/log/DelayBufferedOutputStream.java

@@ -95,11 +95,8 @@ void flushAndReschedule() {
         reschedule();
     }
 
-    @SuppressWarnings("FinalizeDeclaration") // not ideal, but PhantomReference is more of a hassle
-    @Override protected void finalize() throws Throwable {
-        super.finalize();
-        // Odd that this is not the default behavior for BufferedOutputStream.
-        flush();
+    @Override public String toString() {
+        return "DelayBufferedOutputStream[" + out + "]";
     }
 
     private static final class Flush implements Runnable {
@@ -143,6 +140,10 @@ private static final class FlushControlledOutputStream extends FilterOutputStrea
             }
         }
 
+        @Override public String toString() {
+            return "FlushControlledOutputStream[" + out + "]";
+        }
+
     }
 
 }

src/main/java/org/jenkinsci/plugins/workflow/log/FileLogStorage.java

@@ -85,7 +85,7 @@ private FileLogStorage(File log) {
     private synchronized void open() throws IOException {
         if (os == null) {
             os = new FileOutputStream(log, true);
-            bos = new DelayBufferedOutputStream(os);
+            bos = new GCFlushedOutputStream(new DelayBufferedOutputStream(os));
             if (index.isFile()) {
                 try (BufferedReader r = Files.newBufferedReader(index.toPath(), StandardCharsets.UTF_8)) {
                     // TODO would be faster to scan the file backwards for the penultimate \n, then convert the byte sequence from there to EOF to UTF-8 and set lastId accordingly

src/main/java/org/jenkinsci/plugins/workflow/log/GCFlushedOutputStream.java

@@ -0,0 +1,98 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2018 CloudBees, Inc.
+ *
+ * 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.jenkinsci.plugins.workflow.log;
+
+import java.io.BufferedOutputStream;
+import java.io.FilterOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.lang.ref.PhantomReference;
+import java.lang.ref.ReferenceQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import jenkins.util.Timer;
+
+/**
+ * A stream which will be flushed before garbage collection.
+ * {@link BufferedOutputStream} does not do this automatically.
+ */
+final class GCFlushedOutputStream extends FilterOutputStream {
+
+    private static final Logger LOGGER = Logger.getLogger(GCFlushedOutputStream.class.getName());
+
+    GCFlushedOutputStream(OutputStream out) {
+        super(out);
+        FlushRef.register(this, out);
+    }
+
+    @Override public void write(byte[] b, int off, int len) throws IOException {
+        out.write(b, off, len); // super method is surprising
+    }
+
+    @Override public String toString() {
+        return "GCFlushedOutputStream[" + out + "]";
+    }
+
+    /**
+     * Flushes streams prior to garbage collection.
+     * ({@link BufferedOutputStream} does not do this automatically.)
+     * TODO Java 9+ could use java.util.Cleaner
+     */
+    private static final class FlushRef extends PhantomReference<GCFlushedOutputStream> {
+
+        private static final ReferenceQueue<GCFlushedOutputStream> rq = new ReferenceQueue<>();
+
+        static {
+            Timer.get().scheduleWithFixedDelay(() -> {
+                while (true) {
+                    FlushRef ref = (FlushRef) rq.poll();
+                    if (ref == null) {
+                        break;
+                    }
+                    LOGGER.log(Level.FINE, "flushing {0}", ref.out);
+                    try {
+                        ref.out.flush();
+                    } catch (IOException x) {
+                        LOGGER.log(Level.WARNING, null, x);
+                    }
+                }
+            }, 0, 10, TimeUnit.SECONDS);
+        }
+
+        static void register(GCFlushedOutputStream fos, OutputStream out) {
+            new FlushRef(fos, out, rq).enqueue();
+        }
+
+        private final OutputStream out;
+
+        private FlushRef(GCFlushedOutputStream fos, OutputStream out, ReferenceQueue<GCFlushedOutputStream> rq) {
+            super(fos, rq);
+            this.out = out;
+        }
+
+    }
+
+}

src/test/java/org/jenkinsci/plugins/workflow/log/LogStorageTestBase.java

@@ -27,7 +27,9 @@
 import hudson.console.AnnotatedLargeText;
 import hudson.console.HyperlinkNote;
 import hudson.model.TaskListener;
+import hudson.remoting.Channel;
 import hudson.remoting.VirtualChannel;
+import hudson.util.StreamTaskListener;
 import java.io.EOFException;
 import java.io.PrintWriter;
 import java.io.StringWriter;
@@ -37,11 +39,18 @@
 import java.util.Random;
 import java.util.concurrent.Callable;
 import java.util.function.BiFunction;
+import java.util.logging.Formatter;
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.LogRecord;
+import java.util.logging.Logger;
+import java.util.logging.SimpleFormatter;
 import jenkins.security.MasterToSlaveCallable;
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.output.NullOutputStream;
 import org.apache.commons.io.output.NullWriter;
 import org.apache.commons.io.output.WriterOutputStream;
+import static org.hamcrest.Matchers.*;
 import org.jenkinsci.plugins.workflow.cps.CpsFlowDefinition;
 import org.jenkinsci.plugins.workflow.graph.FlowNode;
 import org.jenkinsci.plugins.workflow.job.WorkflowJob;
@@ -51,6 +60,7 @@
 import org.junit.ClassRule;
 import org.junit.Test;
 import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.LoggerRule;
 
 /**
  * Foundation for compliance tests of {@link LogStorage} implementations.
@@ -63,6 +73,8 @@ public abstract class LogStorageTestBase {
 
     @ClassRule public static JenkinsRule r = new JenkinsRule();
 
+    @ClassRule public static LoggerRule logging = new LoggerRule();
+
     /** Create a new storage implementation, but potentially reusing any data initialized in the last {@link Before} setup. */
     protected abstract LogStorage createStorage() throws Exception;
 
@@ -142,6 +154,7 @@ protected static void close(TaskListener listener) throws Exception {
     }
 
     @Test public void remoting() throws Exception {
+        logging.capture(100).record(Channel.class, Level.WARNING);
         LogStorage ls = createStorage();
         TaskListener overall = ls.overallListener();
         overall.getLogger().println("overall from master");
@@ -150,12 +163,15 @@ protected static void close(TaskListener listener) throws Exception {
         long overallPos = assertOverallLog(0, "overall from master\n<span class=\"pipeline-node-1\">step from master\n</span>", true);
         long stepPos = assertStepLog("1", 0, "step from master\n", true);
         VirtualChannel channel = r.createOnlineSlave().getChannel();
+        channel.call(new RemoteLogDumper("agent"));
         channel.call(new RemotePrint("overall from agent", overall));
         channel.call(new RemotePrint("step from agent", step));
+        channel.call(new GC());
         overallPos = assertOverallLog(overallPos, "overall from agent\n<span class=\"pipeline-node-1\">step from agent\n</span>", true);
         stepPos = assertStepLog("1", stepPos, "step from agent\n", true);
         assertEquals(overallPos, assertOverallLog(overallPos, "", true));
         assertEquals(stepPos, assertStepLog("1", stepPos, "", true));
+        assertThat(logging.getMessages(), empty());
     }
     private static final class RemotePrint extends MasterToSlaveCallable<Void, Exception> {
         static {
@@ -173,6 +189,39 @@ private static final class RemotePrint extends MasterToSlaveCallable<Void, Excep
             return null;
         }
     }
+    /** Checking behavior of {@link DelayBufferedOutputStream} garbage collection. */
+    private static final class GC extends MasterToSlaveCallable<Void, Exception> {
+        @Override public Void call() throws Exception {
+            System.gc();
+            System.runFinalization();
+            return null;
+        }
+    }
+    // TODO copied from pipeline-log-cloudwatch; consider whether this should be moved into LoggerRule
+    private static final class RemoteLogDumper extends MasterToSlaveCallable<Void, RuntimeException> {
+        private final String name;
+        private final TaskListener stderr = StreamTaskListener.fromStderr();
+        RemoteLogDumper(String name) {
+            this.name = name;
+        }
+        @Override public Void call() throws RuntimeException {
+            Handler handler = new Handler() {
+                final Formatter formatter = new SimpleFormatter();
+                @Override public void publish(LogRecord record) {
+                    if (isLoggable(record)) {
+                        stderr.getLogger().print(formatter.format(record).replaceAll("(?m)^", "[" + name + "] "));
+                    }
+                }
+                @Override public void flush() {}
+                @Override public void close() throws SecurityException {}
+            };
+            handler.setLevel(Level.ALL);
+            Logger logger = Logger.getLogger(LogStorageTestBase.class.getPackage().getName());
+            logger.setLevel(Level.FINER);
+            logger.addHandler(handler);
+            return null;
+        }
+    }
 
     /**
      * Checks what happens when code using {@link TaskListener#getLogger} prints a line with inadequate synchronization.