[FIXED HUDSON-2394] Improved error handling when Maven fails to start correctly in the m2 project type.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@15501 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/Proc.java

@@ -49,6 +49,11 @@ import java.util.logging.Logger;
 public abstract class Proc {
     private Proc() {}
 
+    /**
+     * Checks if the process is still alive.
+     */
+    public abstract boolean isAlive() throws IOException, InterruptedException;
+
     /**
      * Terminates the process.
      *
@@ -176,6 +181,16 @@ public abstract class Proc {
             }
         }
 
+        @Override
+        public boolean isAlive() throws IOException, InterruptedException {
+            try {
+                proc.exitValue();
+                return false;
+            } catch (IllegalThreadStateException e) {
+                return true;
+            }
+        }
+
         @Override
         public void kill() throws InterruptedException, IOException {
             destroy();
@@ -254,6 +269,11 @@ public abstract class Proc {
                 throw new IOException2("Failed to join the process",e);
             }
         }
+
+        @Override
+        public boolean isAlive() throws IOException, InterruptedException {
+            return !process.isDone();
+        }
     }
 
     private static final Logger LOGGER = Logger.getLogger(Proc.class.getName());