Create ApplicationPid and remove SystemUtils

Create a new ApplicationPid class to remove the need for SystemUtils
and refactor existing calls.

Author: Phillip Webb

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/system/ApplicationPidListener.java

@@ -17,106 +17,76 @@
 package org.springframework.boot.actuate.system;
 
 import java.io.File;
-import java.io.FileNotFoundException;
-import java.io.FileOutputStream;
-import java.io.IOException;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.springframework.boot.ApplicationPid;
 import org.springframework.boot.context.event.ApplicationStartedEvent;
-import org.springframework.boot.util.SystemUtils;
 import org.springframework.context.ApplicationListener;
 import org.springframework.core.Ordered;
+import org.springframework.util.Assert;
 
 /**
  * An {@link org.springframework.context.ApplicationListener} that saves application PID
- * into file
+ * into file. This application listener will be triggered exactly once per JVM.
  * 
- * @since 1.0.2
- *
  * @author Jakub Kubrynski
  * @author Dave Syer
+ * @author Phillip Webb
+ * @since 1.0.2
  */
 public class ApplicationPidListener implements
 		ApplicationListener<ApplicationStartedEvent>, Ordered {
 
-	private static final String DEFAULT_PID_FILE_NAME = "application.pid";
+	private static final Log logger = LogFactory.getLog(ApplicationPidListener.class);
 
-	private static final AtomicBoolean pidFileCreated = new AtomicBoolean(false);
+	private static final String DEFAULT_FILE_NAME = "application.pid";
+
+	private static final AtomicBoolean created = new AtomicBoolean(false);
 
 	private int order = Ordered.HIGHEST_PRECEDENCE + 13;
 
-	private static final Log logger = LogFactory.getLog(ApplicationPidListener.class);
+	private final File file;
 
-	private String pidFileName = DEFAULT_PID_FILE_NAME;
+	/**
+	 * Create a new {@link ApplicationPidListener} instance using the filename
+	 * 'application.pid'.
+	 */
+	public ApplicationPidListener() {
+		this.file = new File(DEFAULT_FILE_NAME);
+	}
 
 	/**
-	 * Sets the pid file name. This file will contain current process id.
-	 *
-	 * @param pidFileName the name of file containing pid
+	 * Create a new {@link ApplicationPidListener} instance with a specified filename.
+	 * @param filename the name of file containing pid
 	 */
-	public ApplicationPidListener(String pidFileName) {
-		this.pidFileName = pidFileName;
+	public ApplicationPidListener(String filename) {
+		Assert.notNull(filename, "Filename must not be null");
+		this.file = new File(filename);
 	}
 
-	public ApplicationPidListener() {
+	/**
+	 * Create a new {@link ApplicationPidListener} instance with a specified file.
+	 * @param file the file containing pid
+	 */
+	public ApplicationPidListener(File file) {
+		Assert.notNull(file, "File must not be null");
+		this.file = file;
 	}
 
 	@Override
 	public void onApplicationEvent(ApplicationStartedEvent event) {
-		if (pidFileCreated.get()) {
-			return;
-		}
-
-		String applicationPid;
-		try {
-			applicationPid = SystemUtils.getApplicationPid();
-		}
-		catch (IllegalStateException ignore) {
-			return;
-		}
-
-		if (pidFileCreated.compareAndSet(false, true)) {
-			File file = new File(this.pidFileName);
-			FileOutputStream fileOutputStream = null;
+		if (created.compareAndSet(false, true)) {
 			try {
-				File parent = file.getParentFile();
-				if (parent != null) {
-					parent.mkdirs();
-				}
-				fileOutputStream = new FileOutputStream(file);
-				fileOutputStream.write(applicationPid.getBytes());
+				new ApplicationPid().write(this.file);
 			}
-			catch (FileNotFoundException e) {
-				logger.warn(String
-						.format("Cannot create pid file %s !", this.pidFileName));
-			}
-			catch (Exception e) {
-				logger.warn(String.format("Cannot write to pid file %s!",
-						this.pidFileName));
-			}
-			finally {
-				if (fileOutputStream != null) {
-					try {
-						fileOutputStream.close();
-					}
-					catch (IOException e) {
-						logger.warn(String.format("Cannot close pid file %s!",
-								this.pidFileName));
-					}
-				}
+			catch (Exception ex) {
+				logger.warn(String.format("Cannot create pid file %s", this.file));
 			}
 		}
 	}
 
-	/**
-	 * Allow pid file to be re-written
-	 */
-	public static void reset() {
-		pidFileCreated.set(false);
-	}
-
 	public void setOrder(int order) {
 		this.order = order;
 	}
@@ -126,4 +96,10 @@ public int getOrder() {
 		return this.order;
 	}
 
+	/**
+	 * Reset the created flag for testing purposes.
+	 */
+	static void reset() {
+		created.set(false);
+	}
 }

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/system/ApplicationPidListenerTest.java

@@ -17,57 +17,47 @@
 package org.springframework.boot.actuate.system;
 
 import java.io.File;
+import java.io.FileReader;
 
 import org.junit.After;
+import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.context.event.ApplicationStartedEvent;
+import org.springframework.util.FileCopyUtils;
 
-import static org.junit.Assert.assertTrue;
+import static org.hamcrest.Matchers.isEmptyString;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertThat;
 
 /**
+ * Tests fpr {@link ApplicationPidListener}.
+ * 
  * @author Jakub Kubrynski
  * @author Dave Syer
  */
 public class ApplicationPidListenerTest {
 
-	private static final String[] NO_ARGS = {};
+	private static final ApplicationStartedEvent EVENT = new ApplicationStartedEvent(
+			new SpringApplication(), new String[] {});
 
+	@Rule
+	public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+	@Before
 	@After
-	public void init() {
+	public void resetListener() {
 		ApplicationPidListener.reset();
 	}
 
 	@Test
-	public void shouldCreatePidFile() {
-		// given
-		String pidFileName = "test.pid";
-		ApplicationPidListener sut = new ApplicationPidListener(pidFileName);
-
-		// when
-		sut.onApplicationEvent(new ApplicationStartedEvent(new SpringApplication(),
-				NO_ARGS));
-
-		// then
-		File pidFile = new File(pidFileName);
-		assertTrue(pidFile.exists());
-		pidFile.delete();
-	}
-
-	@Test
-	public void shouldCreatePidFileParentDirectory() {
-		// given
-		String pidFileName = "target/pid/test.pid";
-		ApplicationPidListener sut = new ApplicationPidListener(pidFileName);
-
-		// when
-		sut.onApplicationEvent(new ApplicationStartedEvent(new SpringApplication(),
-				NO_ARGS));
-
-		// then
-		File pidFile = new File(pidFileName);
-		assertTrue(pidFile.exists());
-		pidFile.delete();
+	public void createPidFile() throws Exception {
+		File file = this.temporaryFolder.newFile();
+		ApplicationPidListener listener = new ApplicationPidListener(file);
+		listener.onApplicationEvent(EVENT);
+		assertThat(FileCopyUtils.copyToString(new FileReader(file)), not(isEmptyString()));
 	}
 
 }

spring-boot/src/main/java/org/springframework/boot/ApplicationPid.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2012-2014 the original author or authors.
+ *
+ * Licensed 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.springframework.boot;
+
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+
+import org.springframework.util.Assert;
+import org.springframework.util.ObjectUtils;
+
+/**
+ * An application process ID.
+ * 
+ * @author Phillip Webb
+ */
+public class ApplicationPid {
+
+	private final String pid;
+
+	public ApplicationPid() {
+		this.pid = getPid();
+	}
+
+	protected ApplicationPid(String pid) {
+		this.pid = pid;
+	}
+
+	private String getPid() {
+		try {
+			String jvmName = ManagementFactory.getRuntimeMXBean().getName();
+			return jvmName.split("@")[0];
+		}
+		catch (Throwable ex) {
+			return null;
+		}
+	}
+
+	@Override
+	public String toString() {
+		return (this.pid == null ? "???" : this.pid);
+	}
+
+	@Override
+	public int hashCode() {
+		return ObjectUtils.nullSafeHashCode(this.pid);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (obj == this) {
+			return true;
+		}
+		if (obj != null && obj instanceof ApplicationPid) {
+			return ObjectUtils.nullSafeEquals(this.pid, ((ApplicationPid) obj).pid);
+		}
+		return false;
+	}
+
+	/**
+	 * Write the PID to the specified file.
+	 * @throws IllegalStateException if no PID is available.
+	 * @throws IOException if the file cannot be written
+	 */
+	public void write(File file) throws IOException {
+		Assert.state(this.pid != null, "No PID available");
+		createParentFolder(file);
+		FileWriter writer = new FileWriter(file);
+		try {
+			writer.append(this.pid);
+		}
+		finally {
+			writer.close();
+		}
+	}
+
+	private void createParentFolder(File file) {
+		File parent = file.getParentFile();
+		if (parent != null) {
+			parent.mkdirs();
+		}
+	}
+
+}

spring-boot/src/main/java/org/springframework/boot/logging/LoggingApplicationListener.java

@@ -16,12 +16,16 @@
 
 package org.springframework.boot.logging;
 
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.springframework.boot.ApplicationPid;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.context.event.ApplicationEnvironmentPreparedEvent;
 import org.springframework.boot.context.event.ApplicationStartedEvent;
-import org.springframework.boot.util.SystemUtils;
 import org.springframework.context.ApplicationEvent;
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.event.SmartApplicationListener;
@@ -33,10 +37,6 @@
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.ResourceUtils;
 
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
 /**
  * An {@link ApplicationListener} that configures a logging framework depending on what it
  * finds on the classpath and in the {@link Environment}. If the environment contains a
@@ -124,13 +124,7 @@ public void onApplicationEvent(ApplicationEvent event) {
 		}
 		else {
 			if (System.getProperty(PID_KEY) == null) {
-				String applicationPid;
-				try {
-					applicationPid = SystemUtils.getApplicationPid();
-				} catch (IllegalStateException e) {
-					applicationPid = "????";
-				}
-				System.setProperty(PID_KEY, applicationPid);
+				System.setProperty(PID_KEY, new ApplicationPid().toString());
 			}
 			LoggingSystem loggingSystem = LoggingSystem.get(ClassUtils
 					.getDefaultClassLoader());