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package sun.jvmstat.monitor;


Utility class proving concenience methods for extracting various
information from an MonitoredVm object.

Author:Brian Doherty
Since:1.5
/**
 * Utility class proving concenience methods for extracting various
 * information from an MonitoredVm object.
 *
 * @author Brian Doherty
 * @since 1.5
 */
public class MonitoredVmUtil {

    
Private constructor - prevent instantiation.

/**
     * Private constructor - prevent instantiation.
     */
    private MonitoredVmUtil() { }

    
Return the Java Virtual Machine Version.

Params:
  • vm – the target MonitoredVm
Returns:String - contains the version of the target JVM or the
                 the string "Unknown" if the version cannot be
                 determined.
/**
     * Return the Java Virtual Machine Version.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the version of the target JVM or the
     *                  the string "Unknown" if the version cannot be
     *                  determined.
     */
    public static String vmVersion(MonitoredVm vm) throws MonitorException {
        StringMonitor ver =
               (StringMonitor)vm.findByName("java.property.java.vm.version");
        return (ver == null) ? "Unknown" : ver.stringValue();
    }

    
Return the command line for the target Java application.

Params:
  • vm – the target MonitoredVm
Returns:String - contains the command line of the target Java
                 application or the the string "Unknown" if the
                 command line cannot be determined.
/**
     * Return the command line for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the command line of the target Java
     *                  application or the the string "Unknown" if the
     *                  command line cannot be determined.
     */
    public static String commandLine(MonitoredVm vm) throws MonitorException {
        StringMonitor cmd = (StringMonitor)vm.findByName("sun.rt.javaCommand");
        return (cmd == null) ? "Unknown" : cmd.stringValue();
    }

    
Return the arguments to the main class for the target Java application.
Returns the arguments to the main class. If the arguments can't be
found, the string "Unknown" is returned.

Params:
  • vm – the target MonitoredVm
Returns:String - contains the arguments to the main class for the
                 target Java application or the the string "Unknown"
                 if the command line cannot be determined.
/**
     * Return the arguments to the main class for the target Java application.
     * Returns the arguments to the main class. If the arguments can't be
     * found, the string "Unknown" is returned.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the arguments to the main class for the
     *                  target Java application or the the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String mainArgs(MonitoredVm vm) throws MonitorException {
        String commandLine = commandLine(vm);

        int firstSpace = commandLine.indexOf(' ');
        if (firstSpace > 0) {
            return commandLine.substring(firstSpace + 1);
        } else if (commandLine.compareTo("Unknown") == 0) {
            return commandLine;
        } else {
            return null;
        }
    }

    
Return the main class for the target Java application.
Returns the main class or the name of the jar file if the application
was started with the -jar option.

Params:
  • vm – the target MonitoredVm
  • fullPath – include the full path to Jar file, where applicable
Returns:String - contains the main class of the target Java
                 application or the the string "Unknown" if the
                 command line cannot be determined.
/**
     * Return the main class for the target Java application.
     * Returns the main class or the name of the jar file if the application
     * was started with the <em>-jar</em> option.
     *
     * @param vm the target MonitoredVm
     * @param fullPath include the full path to Jar file, where applicable
     * @return String - contains the main class of the target Java
     *                  application or the the string "Unknown" if the
     *                  command line cannot be determined.
     */
    public static String mainClass(MonitoredVm vm, boolean fullPath)
                         throws MonitorException {
        String commandLine = commandLine(vm);
        String arg0 = commandLine;

        int firstSpace = commandLine.indexOf(' ');
        if (firstSpace > 0) {
            arg0 = commandLine.substring(0, firstSpace);
        }
        if (!fullPath) {
            /*
             * can't use File.separator() here because the separator
             * for the target jvm may be different than the separator
             * for the monitoring jvm.
             */
            int lastFileSeparator = arg0.lastIndexOf('/');
            if (lastFileSeparator > 0) {
                 return arg0.substring(lastFileSeparator + 1);
            }

            lastFileSeparator = arg0.lastIndexOf('\\');
            if (lastFileSeparator > 0) {
                 return arg0.substring(lastFileSeparator + 1);
            }

            int lastPackageSeparator = arg0.lastIndexOf('.');
            if (lastPackageSeparator > 0) {
                 return arg0.substring(lastPackageSeparator + 1);
            }
        }
        return arg0;
    }

    
Return the JVM arguments for the target Java application.

Params:
  • vm – the target MonitoredVm
Returns:String - contains the arguments passed to the JVM for the
                 target Java application or the the string "Unknown"
                 if the command line cannot be determined.
/**
     * Return the JVM arguments for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the arguments passed to the JVM for the
     *                  target Java application or the the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String jvmArgs(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmArgs = (StringMonitor)vm.findByName("java.rt.vmArgs");
        return (jvmArgs == null) ? "Unknown" : jvmArgs.stringValue();
    }

    
Return the JVM flags for the target Java application.

Params:
  • vm – the target MonitoredVm
Returns:String - contains the flags passed to the JVM for the
                 target Java application or the the string "Unknown"
                 if the command line cannot be determined.
/**
     * Return the JVM flags for the target Java application.
     *
     * @param vm the target MonitoredVm
     * @return String - contains the flags passed to the JVM for the
     *                  target Java application or the the string "Unknown"
     *                  if the command line cannot be determined.
     */
    public static String jvmFlags(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmFlags =
               (StringMonitor)vm.findByName("java.rt.vmFlags");
        return (jvmFlags == null) ? "Unknown" : jvmFlags.stringValue();
    }

    // Index of the sun.rt.jvmCapabilities counter
    private static int IS_ATTACHABLE = 0;
    private static int IS_KERNEL_VM  = 1;

    
Returns true if the VM supports attach-on-demand.

Params:
  • vm – the target MonitoredVm
/**
     * Returns true if the VM supports attach-on-demand.
     *
     * @param vm the target MonitoredVm
     */
    public static boolean isAttachable(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmCapabilities =
               (StringMonitor)vm.findByName("sun.rt.jvmCapabilities");
        if (jvmCapabilities == null) {
             return false;
        } else {
             return jvmCapabilities.stringValue().charAt(IS_ATTACHABLE) == '1';
        }
    }

    
Returns true if the target VM is a kernel VM

Params:
  • vm – the target MonitoredVm
/**
     * Returns true if the target VM is a kernel VM
     *
     * @param vm the target MonitoredVm
     */
    public static boolean isKernelVM(MonitoredVm vm) throws MonitorException {
        StringMonitor jvmCapabilities =
               (StringMonitor)vm.findByName("sun.rt.jvmCapabilities");
        if (jvmCapabilities == null) {
             return false;
        } else {
             return jvmCapabilities.stringValue().charAt(IS_KERNEL_VM) == '1';
        }
    }
}