+ kamon-autoweave: this new module allow attach the AspectJ loadtime weaving agent to a JVM after it has started (you don't need to use -javaagent). This offers extra flexibility but obviously any classes loaded before attachment will not be woven.

2 files changed, 187 insertions, 0 deletions

diff --git a/kamon-autoweave/src/main/scala/kamon/autoweave/Autoweave.scala b/kamon-autoweave/src/main/scala/kamon/autoweave/Autoweave.scala
new file mode 100644
index 00000000..29c4254a
--- /dev/null
+++ b/kamon-autoweave/src/main/scala/kamon/autoweave/Autoweave.scala
@@ -0,0 +1,32 @@
+/* =========================================================================================
+ * Copyright © 2013-2015 the kamon project <http://kamon.io/>
+ *
+ * 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 kamon.autoweave
+
+import kamon.Kamon
+import kamon.autoweave.loader.AgentLoader
+import org.aspectj.weaver.loadtime.Agent
+
+
+object Autoweave {
+    val config = Kamon.config.getConfig("kamon.autowave.options")
+    val verbose = config.getBoolean("verbose")
+    val showWeaveInfo = config.getBoolean("showWeaveInfo")
+
+    System.setProperty("aj.weaving.verbose", verbose.toString)
+    System.setProperty("org.aspectj.weaver.showWeaveInfo", showWeaveInfo.toString)
+
+    AgentLoader.attachAgentToJVM(classOf[Agent])
+  }
diff --git a/kamon-autoweave/src/main/scala/kamon/autoweave/loader/AgentLoader.scala b/kamon-autoweave/src/main/scala/kamon/autoweave/loader/AgentLoader.scala
new file mode 100644
index 00000000..d4efdb85
--- /dev/null
+++ b/kamon-autoweave/src/main/scala/kamon/autoweave/loader/AgentLoader.scala
@@ -0,0 +1,155 @@
+/* =========================================================================================
+ * Copyright © 2013-2015 the kamon project <http://kamon.io/>
+ *
+ * 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 kamon.autoweave.loader
+
+import java.io.{File, FileOutputStream, InputStream}
+import java.lang.management.ManagementFactory
+import java.util
+import java.util.jar.Attributes.Name
+import java.util.jar.{JarEntry, JarOutputStream, Manifest}
+
+import com.sun.tools.attach.spi.AttachProvider
+import com.sun.tools.attach.{VirtualMachine, VirtualMachineDescriptor}
+import sun.tools.attach._
+
+import scala.util.control.NoStackTrace
+import scala.util.{Failure, Success, Try}
+
+object AgentLoader {
+
+  /**
+   * Gets the current JVM PID
+   *
+   * @return Returns the PID
+   */
+
+  private def getPidFromRuntimeMBean: String = {
+    val jvm = ManagementFactory.getRuntimeMXBean.getName
+    val pid = jvm.substring(0, jvm.indexOf('@'))
+    pid
+  }
+
+  /**
+   * Loads an agent into a JVM.
+   *
+   * @param agent The main agent class.
+   * @param resources Array of classes to be included with agent.
+   */
+  def attachAgentToJVM(agent: Class[_], resources: Seq[Class[_]] = Seq.empty): Unit = {
+    val vm = attachToRunningJVM()
+    vm.loadAgent(generateAgentJar(agent, resources).getAbsolutePath)
+    vm.detach()
+  }
+
+  /**
+   * Java variant
+   *
+   * @param agent
+   */
+  def attachAgentToJVM(agent: Class[_]): Unit = attachAgentToJVM(agent, Seq.empty)
+
+  /**
+   * Generates a temporary agent file to be loaded.
+   *
+   * @param agent     The main agent class.
+   * @param resources Array of classes to be included with agent.
+   * @return Returns a temporary jar file with the specified classes included.
+   */
+  private def generateAgentJar(agent: Class[_], resources: Seq[Class[_]]): File = {
+    val jarFile = File.createTempFile("agent", ".jar")
+    jarFile.deleteOnExit()
+
+    val manifest = new Manifest()
+    val mainAttributes = manifest.getMainAttributes
+    // Create manifest stating that agent is allowed to transform classes
+    mainAttributes.put(Name.MANIFEST_VERSION, "1.0")
+    mainAttributes.put(new Name("Agent-Class"), agent.getName)
+    mainAttributes.put(new Name("Can-Retransform-Classes"), "true")
+    mainAttributes.put(new Name("Can-Redefine-Classes"), "true")
+
+    val jos = new JarOutputStream(new FileOutputStream(jarFile), manifest)
+
+    jos.putNextEntry(new JarEntry(agent.getName.replace('.', '/') + ".class"))
+
+    jos.write(getBytesFromStream(agent.getClassLoader.getResourceAsStream(unqualify(agent))))
+    jos.closeEntry()
+
+    for (clazz ← resources) {
+      val name = unqualify(clazz)
+      jos.putNextEntry(new JarEntry(name))
+      jos.write(getBytesFromStream(clazz.getClassLoader.getResourceAsStream(name)))
+      jos.closeEntry()
+    }
+
+    jos.close()
+    jarFile
+  }
+
+  /**
+   * Gets bytes from InputStream.
+   *
+   * @param stream
+   * The InputStream.
+   * @return
+   * Returns a byte[] representation of given stream.
+   */
+  private def getBytesFromStream(stream: InputStream): Array[Byte] = {
+    Stream.continually(stream.read).takeWhile(_ != -1).map(_.toByte).toArray
+  }
+
+  private def unqualify(clazz: Class[_]): String = clazz.getName.replace('.', '/') + ".class"
+
+  /**
+    * Gets the current HotSpotVirtualMachine implementation otherwise a failure.
+    *
+    * @return
+    * Returns the HotSpotVirtualMachine implementation of the running JVM.
+    */
+  private def findVirtualMachineImplementation(): Try[Class[_ <: HotSpotVirtualMachine]] = System.getProperty("os.name") match  {
+    case os if os.startsWith("Windows")  => Success(classOf[WindowsVirtualMachine])
+    case os if os.startsWith("Mac OS X") => Success(classOf[BsdVirtualMachine])
+    case os if os.startsWith("Solaris") => Success(classOf[SolarisVirtualMachine])
+    case os if os.startsWith("Linux") || os.startsWith("LINUX") => Success(classOf[LinuxVirtualMachine])
+    case other => Failure(new RuntimeException(s"Cannot use Attach API on unknown OS: $other") with NoStackTrace)
+  }
+
+  /**
+    * Attach to the running JVM.
+    *
+    * @return
+    * Returns the attached VirtualMachine
+    */
+  private def attachToRunningJVM(): VirtualMachine = {
+    val AttachProvider = new AttachProvider() {
+      override def name(): String = null
+      override def `type`(): String = null
+      override def attachVirtualMachine(id: String): VirtualMachine = null
+      override def listVirtualMachines(): util.List[VirtualMachineDescriptor] = null
+    }
+
+    findVirtualMachineImplementation() match {
+      case Success(vmClass) =>
+        val pid = getPidFromRuntimeMBean
+        // This is only done with Reflection to avoid the JVM pre-loading all the XyzVirtualMachine classes.
+        val vmConstructor = vmClass.getConstructor(classOf[AttachProvider], classOf[String])
+        val newVM = vmConstructor.newInstance(AttachProvider, pid)
+        newVM.asInstanceOf[VirtualMachine]
+      case Failure(reason) => throw reason
+    }
+  }
+}
+
+