From 72a392327a933b45fa59ec6ef54ceba09991781c Mon Sep 17 00:00:00 2001
From: Caleb Metz <135133572+cmetz100@users.noreply.github.com>
Date: Thu, 27 Jul 2023 15:14:54 -0400
Subject: [PATCH] Update management agent logic and comments for java 7 vs 8 vs
 9 (#457)

* restructured loadjmxagent

* added version log msg

* reverted to maven target 1.7

* updated comments

* updated formatting

* updated format

* updated more formatting
---
 .../datadog/jmxfetch/AttachApiConnection.java | 41 ++++++++++---------
 .../datadog/jmxfetch/ConnectionFactory.java   |  2 +
 2 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/src/main/java/org/datadog/jmxfetch/AttachApiConnection.java b/src/main/java/org/datadog/jmxfetch/AttachApiConnection.java
index 6b975ccb9..db05d4c94 100644
--- a/src/main/java/org/datadog/jmxfetch/AttachApiConnection.java
+++ b/src/main/java/org/datadog/jmxfetch/AttachApiConnection.java
@@ -59,31 +59,32 @@ private String getJmxUrlForProcessRegex(String processRegex)
     }
 
     // management-agent.jar has been removed in java 8+
-    // Once JMXFetch drops java7 support, this should be simplified to simply invoke
-    // vm.startLocalManagementAgent
+    // Once JMXFetch drops java 7 support, this should be simplified to simply invoke 
+    // vm.startLocalManagementAgent which is accessible in java 8 if tools.jar is added 
+    // to the classpath and java 9+ by default 
     // ref https://bugs.openjdk.org/browse/JDK-8179063
     private void loadJmxAgent(com.sun.tools.attach.VirtualMachine vm) throws IOException {
-        String agent =
-                vm.getSystemProperties().getProperty("java.home")
-                        + File.separator
-                        + "lib"
-                        + File.separator
-                        + "management-agent.jar";
         try {
-            vm.loadAgent(agent);
-        } catch (Exception e) {
-            log.warn("Error initializing JMX agent from management-agent.jar", e);
-
+            Method method = com.sun.tools.attach.VirtualMachine
+                .class.getMethod("startLocalManagementAgent");
+            log.info("Found startLocalManagementAgent API, attempting to use it.");
+            method.invoke(vm);
+        } catch (NoSuchMethodException noMethodE) {
+            log.warn("startLocalManagementAgent method not found, must be on java 7", noMethodE);
+            String agent = vm.getSystemProperties().getProperty("java.home")
+                + File.separator
+                + "lib"
+                + File.separator
+                + "management-agent.jar";
             try {
-                Method method = com.sun.tools.attach.VirtualMachine
-                    .class.getMethod("startLocalManagementAgent");
-                log.info("Found startLocalManagementAgent API, attempting to use it.");
-                method.invoke(vm);
-            } catch (NoSuchMethodException noMethodE) {
-                log.warn("startLocalManagementAgent method not found, must be on java7", noMethodE);
-            } catch (Exception reflectionE) {
-                log.warn("Error invoking the startLocalManagementAgent method", reflectionE);
+                vm.loadAgent(agent);
+            } catch (Exception e) {
+                log.warn("Error initializing JMX agent from management-agent.jar", e);
             }
+        } catch (Exception reflectionE) {
+            log.warn("Error invoking the startLocalManagementAgent method", reflectionE);
         }
+        
+        
     }
 }
diff --git a/src/main/java/org/datadog/jmxfetch/ConnectionFactory.java b/src/main/java/org/datadog/jmxfetch/ConnectionFactory.java
index 61b7e32db..8855e42a6 100644
--- a/src/main/java/org/datadog/jmxfetch/ConnectionFactory.java
+++ b/src/main/java/org/datadog/jmxfetch/ConnectionFactory.java
@@ -24,6 +24,8 @@ public static Connection createConnection(Map<String, Object> connectionParams)
 
         if (connectionParams.get(PROCESS_NAME_REGEX) != null) {
             try {
+                // AttachNotSupportedException is accessible in java 7 and 8 through tools.jar 
+                // and java 9+ by default
                 Class.forName("com.sun.tools.attach.AttachNotSupportedException");
             } catch (ClassNotFoundException e) {
                 throw new IOException(