Please review -XshowSettings a java launcher option.

[David Schlosnagle]

Kumar,

Do you need all of the StringBuilder/StringBuffer to buffer the output
prior to writing to the PrintStream? Using the PrintStream directly
would also allow it to handle the newlines. I was envisaging something
like this:

private static void printVmSettings(PrintStream ostream, long maxHeapSize,
        long stackSize, boolean isServer) {

    String maxHeapSizeString = scaleValue((maxHeapSize == 0)
            ? Runtime.getRuntime().maxMemory()
            : maxHeapSize);

    String stackSizeString = (stackSize == 0)
            ? "OS default"
            : scaleValue(stackSize);

    ostream.println();
    ostream.println(VM_SETTINGS);
    ostream.print(INDENT + "Stack Size (-Xss): ");
    ostream.println(stackSizeString);
    ostream.print(INDENT + "Max. Heap Size (-Xmx): ");
    ostream.println(maxHeapSizeString);
    ostream.print(INDENT + "Ergonomics Class (server or client): ");
    ostream.println((isServer) ? "server" : "client");
    ostream.print(INDENT + "Using VM: ");
    ostream.println(System.getProperty("java.vm.name"));
}

private static boolean isPath(String key) {
    return key.endsWith(".dirs") || key.endsWith(".path");
}

private static void prettyPrintValue(PrintStream ostream, String key,
String value) {
    ostream.print(INDENT);
    ostream.print(key);
    ostream.print(" = ");

    if (!isPath(key)) {
        ostream.println(value);
        return;
    }

    // pretty print the path values as a list
    String pathsep = System.getProperty("path.separator");
    String[] values = value.split(pathsep);
    int len = values.length;
    int lastline = len - 1;
    for (int i = 0 ; i < len ; i++) {
        if (i == 0) { // first line treated specially
            ostream.print(values[i]);
            ostream.println(pathsep);
        } else { // following lines prefix with indents
            ostream.print(INDENT + INDENT);
            ostream.print(values[i]);
            if (i != lastline) { // if not the last line suffix the pathsep
                ostream.print(pathsep);
            }
            ostream.println();
        }
    }
}

private static void printProperties(PrintStream ostream) {
    Properties p = System.getProperties();
    List<String> sortedPropertyKeys = new ArrayList<>();
    sortedPropertyKeys.addAll(p.stringPropertyNames());
    Collections.sort(sortedPropertyKeys);
    ostream.println();
    ostream.println(PROP_SETTINGS);
    for (String x : sortedPropertyKeys) {
        prettyPrintValue(ostream, x, p.getProperty(x));
    }
}

private static void prettyPrintLocales(PrintStream ostream) {
    ostream.println();
    ostream.print(INDENT + "available locales = ");
    Locale[] locales = Locale.getAvailableLocales();
    int len = locales.length;
    int lastline = len - 1 ;
    for (int i = 0 ; i < len ; i++) {
        ostream.print(locales[i]);
        if (i != lastline) {
            ostream.print(",");
        }
        // print columns of 8
        if ((i + 1) % 8 == 0) {
            ostream.println();
            ostream.print(INDENT + INDENT);
        } else {
            ostream.print(" ");
        }
    }
}

private static void printLocale(PrintStream ostream) {
    Locale locale = Locale.getDefault();
    ostream.println();
    ostream.println(LOCALE_SETTINGS);
    ostream.print(INDENT+"default locale: ");
    ostream.print(locale.getDisplayLanguage());
    prettyPrintLocales(ostream);
    ostream.println();
}

- Dave

On Thu, Nov 11, 2010 at 7:42 PM, Kumar Srinivasan
<kumar.x.srinivasan at oracle.com> wrote:
>
> Hi Mandy,
>
>>
>> java.c
>> line 1031: this doesn't catch invalid option if it has the -XshowSettings prefix e.g. -XshowSettingsJunk.
>
> Will fix it.
>
>> line 1032: Perhaps you could store the suboption ("all", "vm", etc) rather than the entire option string.
>
> I want to keep all the parsing logic as much as possible  in java.
>
>> line 1507-1511: should these lines align with the argument "env"  to CallStaticVoidMethod method in line 1506?
>
> Fixed.
>>
>> LauncherHelper.java
>> line 106-109: if optionFlag is just the suboption to -XshowSettings, these lines can be removed.
>> line 150-152: Runtime.maxMemory() is not equivalent to -Xmx value.  Perhaps -XshowSettings always prints Runtime.maxMemory() and print -Xmx if set in the command line?
>
> That is exactly what is happening ie. if the launcher has been given the -Xmx flag
> then that is displayed, if not LauncherHelper will use some means to display any
> value it can get from Java libraries so for now we use Runtime.maxMemory().
>
>
>>
>> line 176, 188, 190-191, 195, and other lines in printPrintLocales and printLocale methods:
>> - the assignment to the buf and out variable to itself (returned from StringBuffer.append() method) is not necessary.
>
> Yes fixed, I missed these.
>
>>
>> line 174: would it be better to pass the StringBuilder to the printPrintValue method so that it can avoid creating a new StringBuilder instance for each property?
>
> We have to create the StringBuilder somewhere it is either in the prettyPrintValue or the calling
> method, I will convert it to StringBuilder and pass it into prettyPrintValue.
>
>>
>> line 213-214: same comment as the above.   And should it use StringBuilder instead?
>
> Yes.
>
> Thanks for the review.!
>
> Kumar
>
>>
>> Mandy
>>>
>>> This will print all the known settings/properties/locales
>>> supported and known  to Java, this has  been a long standing request.
>>>
>>> A sample output attached below.
>>>
>>> Note: the -X option specifically is being used so we can evolve this option
>>> and add more useful information, in future versions of java.
>>>
>>> Thanks
>>> Kumar
>>>
>>>
>>>
>>
>