Please review -XshowSettings a java launcher option.

[Kumar Srinivasan]

Hi David,

Good idea, but  I did not use that method  because of all the String
concatenation  PrintStream.print has  to perform, if so then we can
simply use a String.

So my thinking was to use the StringBuilder to assemble the String and
print it out in one shot.

ostream(INDENT + INDENT);

or instead:
ostream.print(INDENT);
ostream.print(INDENT);
...
....

that would mean more io calls.

I have a time pressure to get this in, I can fix/address this later as a bug
if need be.

Thanks for your review.

Kumar

> 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
>>>>
>>>>
>>>>