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src/main/java/com/oracle/avatar/js/log/LogQueue.java

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+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.oracle.avatar.js.log;
+
+import java.io.IOException;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import com.oracle.avatar.js.eventloop.DaemonThreadFactory;
+
+public class LogQueue {
+
+    private final BlockingQueue<LogEvent> logQueue = new LinkedBlockingQueue<>();
+
+    private final ThreadFactory logThreadFactory = new DaemonThreadFactory("avatar-js.log");
+
+    private final AtomicBoolean logThreadStarted = new AtomicBoolean(false);
+
+    private final Thread logThread = logThreadFactory.newThread(() -> {
+        while (true) {
+            try {
+                logQueue.take().write();
+            } catch (final IOException | InterruptedException ignore) {
+                return;
+            }
+        }
+    });
+
+    private final AtomicBoolean logThreadStopped = new AtomicBoolean(false);
+
+    public void log(final LogEvent event) {
+        logQueue.add(event);
+
+        // start log thread lazily on the very first log event
+        if (logThreadStarted.compareAndSet(false, true)) {
+            logThread.start();
+        }
+    }
+
+    public void shutdown() {
+        if (logThreadStopped.compareAndSet(false, true)) {
+            logThread.interrupt();
+        }
+    }
+}