Reoragnize the startup procedure.

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/boot/AgentPackageNotFoundException.java

+/*
+ * Copyright 2017, OpenSkywalking Organization All rights reserved.
+ *
+ * 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.
+ *
+ * Project repository: https://github.com/OpenSkywalking/skywalking
+ */
+
+package org.skywalking.apm.agent.core.boot;
+
+/**
+ * @author wusheng
+ */
+public class AgentPackageNotFoundException extends Exception {
+    public AgentPackageNotFoundException(String message) {
+        super(message);
+    }
+}

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/boot/AgentPackagePath.java

+/*
+ * Copyright 2017, OpenSkywalking Organization All rights reserved.
+ *
+ * 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.
+ *
+ * Project repository: https://github.com/OpenSkywalking/skywalking
+ */
+
+package org.skywalking.apm.agent.core.boot;
+
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URL;
+import org.skywalking.apm.agent.core.logging.SystemOutWriter;
+import org.skywalking.apm.logging.ILog;
+import org.skywalking.apm.logging.LogManager;
+
+/**
+ * @author wusheng
+ */
+public class AgentPackagePath {
+    private static final ILog logger = LogManager.getLogger(AgentPackagePath.class);
+
+    private static File AGENT_PACKAGE_PATH;
+
+    public static File getPath() throws AgentPackageNotFoundException {
+        if (AGENT_PACKAGE_PATH == null) {
+            AGENT_PACKAGE_PATH = findPath();
+        }
+        return AGENT_PACKAGE_PATH;
+    }
+
+    private static File findPath() throws AgentPackageNotFoundException {
+        String classResourcePath = AgentPackagePath.class.getName().replaceAll("\\.", "/") + ".class";
+
+        URL resource = AgentPackagePath.class.getClassLoader().getSystemClassLoader().getResource(classResourcePath);
+        if (resource != null) {
+            String urlString = resource.toString();
+
+            SystemOutWriter.INSTANCE.write(urlString);
+            logger.debug(urlString);
+
+            urlString = urlString.substring(urlString.indexOf("file:"), urlString.indexOf('!'));
+            File agentJarFile = null;
+            try {
+                agentJarFile = new File(new URL(urlString).getFile());
+            } catch (MalformedURLException e) {
+                SystemOutWriter.INSTANCE.write("Can not locate agent jar file by url:" + urlString);
+                logger.error(e, "Can not locate agent jar file by url: {}", urlString);
+            }
+            if (agentJarFile.exists()) {
+                return agentJarFile.getParentFile();
+            }
+        }
+
+        SystemOutWriter.INSTANCE.write("Can not locate agent jar file.");
+        logger.info("Can not locate agent jar file.");
+        throw new AgentPackageNotFoundException("Can not locate agent jar file.");
+    }
+
+}

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/conf/ConfigNotFoundException.java

+/*
+ * Copyright 2017, OpenSkywalking Organization All rights reserved.
+ *
+ * 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.
+ *
+ * Project repository: https://github.com/OpenSkywalking/skywalking
+ */
+
+package org.skywalking.apm.agent.core.conf;
+
+/**
+ * @author wusheng
+ */
+public class ConfigNotFoundException extends Exception {
+    public ConfigNotFoundException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public ConfigNotFoundException(String message) {
+        super(message);
+    }
+}

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/conf/SnifferConfigInitializer.java

@@ -22,9 +22,9 @@ import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.InputStream;
-import java.net.MalformedURLException;
-import java.net.URL;
 import java.util.Properties;
+import org.skywalking.apm.agent.core.boot.AgentPackageNotFoundException;
+import org.skywalking.apm.agent.core.boot.AgentPackagePath;
 import org.skywalking.apm.logging.ILog;
 import org.skywalking.apm.logging.LogManager;
 import org.skywalking.apm.util.ConfigInitializer;
@@ -52,32 +52,17 @@ public class SnifferConfigInitializer {
      * 1. applicationCode. "-DapplicationCode=" or  {@link Config.Agent#APPLICATION_CODE}
      * 2. servers. "-Dservers=" or  {@link Config.Collector#SERVERS}
      */
-    public static void initialize() {
+    public static void initialize() throws ConfigNotFoundException, AgentPackageNotFoundException {
         InputStream configFileStream;
 
-        configFileStream = loadConfigBySystemProperty();
+        configFileStream = loadConfigFromAgentFolder();
 
-        if (configFileStream == null) {
-            configFileStream = SnifferConfigInitializer.class.getResourceAsStream(CONFIG_FILE_NAME);
-
-            if (configFileStream == null) {
-                logger.info("No config file found, according system property '-Dconfig'.");
-                configFileStream = loadConfigFromAgentFolder();
-            } else {
-                logger.info("{} file found in class path.", CONFIG_FILE_NAME);
-            }
-        }
-
-        if (configFileStream == null) {
-            logger.info("No {} found, sky-walking is going to run in default config.", CONFIG_FILE_NAME);
-        } else {
-            try {
-                Properties properties = new Properties();
-                properties.load(configFileStream);
-                ConfigInitializer.initialize(properties, Config.class);
-            } catch (Exception e) {
-                logger.error("Failed to read the config file, sky-walking is going to run in default config.", e);
-            }
+        try {
+            Properties properties = new Properties();
+            properties.load(configFileStream);
+            ConfigInitializer.initialize(properties, Config.class);
+        } catch (Exception e) {
+            logger.error("Failed to read the config file, sky-walking is going to run in default config.", e);
         }
 
         String applicationCode = System.getProperty("applicationCode");
@@ -131,50 +116,16 @@ public class SnifferConfigInitializer {
      *
      * @return the config file {@link InputStream}, or null if not needEnhance.
      */
-    private static InputStream loadConfigFromAgentFolder() {
-        String agentBasePath = initAgentBasePath();
-        if (!StringUtil.isEmpty(agentBasePath)) {
-            File configFile = new File(agentBasePath, CONFIG_FILE_NAME);
-            if (configFile.exists() && configFile.isFile()) {
-                try {
-                    logger.info("{} file found in agent folder.", CONFIG_FILE_NAME);
-                    return new FileInputStream(configFile);
-                } catch (FileNotFoundException e) {
-                    logger.error(e, "Fail to load {} in path {}, according auto-agent-folder mechanism.", CONFIG_FILE_NAME, agentBasePath);
-                }
-            }
-        }
-
-        logger.info("No {} file found in agent folder.", CONFIG_FILE_NAME);
-        return null;
-    }
-
-    /**
-     * Try to allocate the skywalking-agent.jar
-     * Some config files or output resources are from this path.
-     *
-     * @return he path, where the skywalking-agent.jar is
-     */
-    private static String initAgentBasePath() {
-        String classResourcePath = SnifferConfigInitializer.class.getName().replaceAll("\\.", "/") + ".class";
-
-        URL resource = SnifferConfigInitializer.class.getClassLoader().getSystemClassLoader().getResource(classResourcePath);
-        if (resource != null) {
-            String urlString = resource.toString();
-            logger.debug(urlString);
-            urlString = urlString.substring(urlString.indexOf("file:"), urlString.indexOf('!'));
-            File agentJarFile = null;
+    private static InputStream loadConfigFromAgentFolder() throws AgentPackageNotFoundException, ConfigNotFoundException {
+        File configFile = new File(AgentPackagePath.getPath(), CONFIG_FILE_NAME);
+        if (configFile.exists() && configFile.isFile()) {
             try {
-                agentJarFile = new File(new URL(urlString).getFile());
-            } catch (MalformedURLException e) {
-                logger.error(e, "Can not locate agent jar file by url:", urlString);
-            }
-            if (agentJarFile.exists()) {
-                return agentJarFile.getParentFile().getAbsolutePath();
+                logger.info("{} file found in agent folder.", CONFIG_FILE_NAME);
+                return new FileInputStream(configFile);
+            } catch (FileNotFoundException e) {
+                throw new ConfigNotFoundException("Fail to load agent.config", e);
             }
         }
-
-        logger.info("Can not locate agent jar file.");
-        return null;
+        throw new ConfigNotFoundException("Fail to load agent.config");
     }
 }

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/plugin/PluginBootstrap.java

@@ -21,6 +21,9 @@ package org.skywalking.apm.agent.core.plugin;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.List;
+import org.skywalking.apm.agent.core.boot.AgentPackageNotFoundException;
+import org.skywalking.apm.agent.core.boot.AgentPackagePath;
+import org.skywalking.apm.agent.core.plugin.loader.PluginClassLoader;
 import org.skywalking.apm.logging.ILog;
 import org.skywalking.apm.logging.LogManager;
 
@@ -39,7 +42,9 @@ public class PluginBootstrap {
      *
      * @return plugin definition list.
      */
-    public List<AbstractClassEnhancePluginDefine> loadPlugins() {
+    public List<AbstractClassEnhancePluginDefine> loadPlugins() throws AgentPackageNotFoundException {
+        PluginClassLoader.initAndGet(AgentPackagePath.getPath());
+
         PluginResourcesResolver resolver = new PluginResourcesResolver();
         List<URL> resources = resolver.getResources();
 

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/plugin/loader/PluginClassLoader.java

+/*
+ * Copyright 2017, OpenSkywalking Organization All rights reserved.
+ *
+ * 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.
+ *
+ * Project repository: https://github.com/OpenSkywalking/skywalking
+ */
+
+package org.skywalking.apm.agent.core.plugin.loader;
+
+import java.io.File;
+import java.io.FilenameFilter;
+import java.io.IOException;
+import java.net.URL;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.jar.JarFile;
+import org.skywalking.apm.logging.ILog;
+import org.skywalking.apm.logging.LogManager;
+
+/**
+ * The <code>PluginClassLoader</code> represents a classloader,
+ * which is in charge of finding plugins and interceptors.
+ *
+ * @author wusheng
+ */
+public class PluginClassLoader extends ClassLoader {
+    private static final ILog logger = LogManager.getLogger(PluginClassLoader.class);
+    private static PluginClassLoader LOADER;
+
+    private List<File> classpath;
+    private List<JarFile> allJars;
+    private ReentrantLock jarScanLock = new ReentrantLock();
+
+    public static PluginClassLoader get() {
+        return LOADER;
+    }
+
+    public static PluginClassLoader initAndGet(File agentDictionary) {
+        LOADER = new PluginClassLoader(agentDictionary);
+        return get();
+    }
+
+    private PluginClassLoader(File agentDictionary) {
+        super(PluginClassLoader.class.getClassLoader());
+        classpath = new LinkedList<File>();
+        classpath.add(new File(agentDictionary, "plugins"));
+        classpath.add(new File(agentDictionary, "activations"));
+    }
+
+    @Override
+    protected Class<?> findClass(String name) throws ClassNotFoundException {
+        throw new ClassNotFoundException(name);
+    }
+
+    @Override
+    protected URL findResource(String name) {
+        getAllJars();
+        throw new RuntimeException("");
+    }
+
+    private List<JarFile> getAllJars() {
+        if (allJars == null) {
+            jarScanLock.lock();
+            try {
+                if (allJars == null) {
+                    allJars = new LinkedList<JarFile>();
+                    for (File path : classpath) {
+                        if (path.exists() && path.isDirectory()) {
+                            String[] jarFileNames = path.list(new FilenameFilter() {
+                                @Override public boolean accept(File dir, String name) {
+                                    return name.endsWith(".jar");
+                                }
+                            });
+                            for (String fileName : jarFileNames) {
+                                try {
+                                    JarFile jar = new JarFile(fileName);
+                                    allJars.add(jar);
+                                } catch (IOException e) {
+                                    logger.error(e, "{} jar file can't be resolved", fileName);
+                                }
+                            }
+                        }
+                    }
+                }
+            } finally {
+                jarScanLock.unlock();
+            }
+        }
+
+        return allJars;
+    }
+}

apm-sniffer/apm-agent/src/main/java/org/skywalking/apm/agent/SkyWalkingAgent.java

@@ -58,11 +58,17 @@ public class SkyWalkingAgent {
      * @throws PluginException
      */
     public static void premain(String agentArgs, Instrumentation instrumentation) throws PluginException {
-        SnifferConfigInitializer.initialize();
+        final PluginFinder pluginFinder;
+        try {
+            SnifferConfigInitializer.initialize();
 
-        final PluginFinder pluginFinder = new PluginFinder(new PluginBootstrap().loadPlugins());
+            pluginFinder = new PluginFinder(new PluginBootstrap().loadPlugins());
 
-        ServiceManager.INSTANCE.boot();
+            ServiceManager.INSTANCE.boot();
+        } catch (Exception e) {
+            logger.error(e, "skywalking agent shutdown.");
+            return;
+        }
 
         Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
             @Override public void run() {