+1 to everything Nick said.
On 26 January 2014 16:40, Nick Williams <nicho...@nicholaswilliams.net>wrote:
> I would be OK with getting rid of the ordinal. It makes it less enum-like,
> but I agree that the ordinal really has little purpose now. The intLevel is
> more important.
>
> Here may be the best approach I can think of for calculating the
> StandardLevel-equivalent on instantiation:
>
> public static Level OFF = new Level("OFF", 0, StandardLevel.OFF) {};
> ...
> public static Level ALL = new Level("ALL", Integer.MAX_VALUE,
> StandardLevel.ALL);
>
> ...
>
> private Level(String name, int intLevel, StandardLevel standardLevel)
> { // this is the only c-tor standard levels use
> // same logic as current constructor
> this.standardLevel = standardLevel;
> }
>
> protected Level(String name, int intLevel) { // this is the only c-tor
> custom levels use
> this(name, intLevel, Level.calculateStandardLevel(intLevel));
> }
>
> public enum StandardLevel {
> OFF, FATAL, ERROR, WARN, INFO, DEBUG, TRACE, ALL
> }
>
> Thoughts?
>
> N
>
> On Jan 26, 2014, at 4:02 PM, Ralph Goers wrote:
>
> > I do have one other comment. You mention that the ordinal value isn’t
> guaranteed because the levels might be instantiated in a different order
> each time. An alternative wold be to just get rid of the ordinal. It
> isn’t used anywhere by anything and when custom values are added they will
> be added after the standard levels, which is correct but might not be what
> you would expect. Eliminating that would allow the static initialization
> to stay as it is and get rid of the need for synchronization in the
> constructor.
> >
> > Ralph
> >
> > On Jan 26, 2014, at 12:41 PM, Nick Williams <
> nicho...@nicholaswilliams.net> wrote:
> >
> >> Some (ok, a lot of) feedback:
> >>
> >> - `private static ConcurrentMap<String, Level> levels` should be final.
> >>
> >> - `private static Object constructorLock` should be final. In fact,
> code inspection flags this as a warning since code synchronizes on it.
> >>
> >> - The standard Level constants should be instantiated in a static
> initializer like in my original code. Otherwise the order they are
> instantiated in is unpredictable, and DEBUG (for example) may even have a
> different ordinal each time the JVM starts.
> >>
> >> - Level isn't abstract. However, you use `new Level("xxx", n) {}`
> (brackets) for Level.OFF, ExtendedLevels.NOTE, and ExtendedLevels.DETAIL,
> but you use `new Level("xxx", n)` (no brackets) for other levels. IMO,
> Level should be abstract (so that there's always exactly one instance of
> every class that extends Level, just like a real enum), and the levels
> should all use {} to construct. However, if we don't make Level abstract,
> then we should remove {} from OFF, NOTE, and DETAIL because it's
> unnecessary.
> >>
> >> - The way StdLevel appears in the middle of Level separates its static
> fields from its instance fields, constructor, and methods. It makes it
> difficult to read. I have to scroll pass StdLevel to see the rest of Level.
> Can we please move StdLevel to the bottom of Level?
> >>
> >> - This is more personal preference, but I don't like abbreviating
> things in class names. What is Std? We may know, but does everyone? To
> someone unfamiliar with English, Standard is easy to translate, but they
> have to first figure out that Std is short for Std. Can be please
> un-abbreviate this to StandardLevel?
> >>
> >> - I disagree with this approach:
> >>
> >> if (levels.containsKey(name)) {
> >> Level level = levels.get(name);
> >> if (level.intLevel() != intLevel) {
> >> throw new IllegalArgumentException("Level " + name +
> " has already been defined.");
> >> }
> >> ordinal = level.ordinal;
> >> }
> >>
> >> This allows multiple Levels with the same name/intLevel to be
> instantiated, which prevents equality testing (level == Level.OFF) from
> being 100% deterministic. It should really be this:
> >>
> >> if (levels.containsKey(name)) {
> >> throw new IllegalArgumentException("Level " + name + "
> has already been defined.");
> >> }
> >>
> >> - I think we should make all of the methods of Level final. Custom
> levels shouldn't be able to change their behavior, IMO. Alternatively, if
> we don't make Level abstract, we should make it final.
> >>
> >> - Level has no JavaDoc. The Level constants in Level have no JavaDoc.
> That needs to be fixed.
> >>
> >> - I'm still not convinced StdLevel/StandardLevel is necessary. It seems
> like an anti-pattern to me. From what I can tell (please let me know if I'm
> missing something), StdLevel's entire purpose is to allow us to still
> switch on the standard levels. I think that's a bad reason to create an
> enum whose constants mirror Level. The primary problem with the StdLevel is
> that the conversion from a Level to a StdLevel in many cases happens __on
> every logging event__. That's going to be hugely inefficient. Really, when
> a custom Level is created, it should be created with an equivalent standard
> Level (or StdLevel). There are several ways to accomplish this that are
> open to discussion, but I don't think the current StdLevel.getStdLevel is
> the right approach. One alternative:
> >>
> >> private final Level standardLevel;
> >>
> >> protected Level(String name, int level, Level mapToOtherFrameworksAs)
> {
> >> this(name, level);
> >> this.standardLevel = mapToOtherFrameworksAs;
> >> }
> >>
> >> private Level(String name, int level) {
> >> // same as now
> >> this.standardLevel = this;
> >> }
> >>
> >> public final Level getStandardLevel() {
> >> return this.standardLevel;
> >> }
> >>
> >> This does, admittedly, have some problems. Another alternative that I
> could also be happy with that keeps the StandardLevel enum:
> >>
> >> private final StandardLevel standardLevel;
> >>
> >> protected Level(String name, int level, StandardLevel
> mapToOtherFrameworksAs) {
> >> this(name, level);
> >> this.standardLevel = mapToOtherFrameworksAs;
> >> }
> >>
> >> private Level(String name, int level) {
> >> // same as now
> >> this.standardLevel = this;
> >> }
> >>
> >> public final StandardLevel getStandardLevel() {
> >> return this.standardLevel;
> >> }
> >>
> >> Nick
> >>
> >> On Jan 26, 2014, at 1:38 PM, Ralph Goers wrote:
> >>
> >>> I’ve committed the changes. Take a look at ExtendedLevels.java,
> ExtendedLevelTest.java and log4j-customLevel.xml in the log4j-core test
> directories to see how it works.
> >>>
> >>> Ralph
> >>>
> >>> On Jan 26, 2014, at 1:19 AM, Remko Popma <remko.po...@gmail.com>
> wrote:
> >>>
> >>>> I'm very curious! Can't wait to see it. Go for it!
> >>>>
> >>>> On Sunday, January 26, 2014, Ralph Goers <ralph.go...@dslextreme.com>
> wrote:
> >>>> I have completed the work on custom levels. It uses a variation of
> Nick’s “extensible enum” class. The major difference with what he proposed
> is that the custom enums must be declared in a class annotated with
> @Plugin(name=“xxxx” category=“Level”) for them to be usable during
> configuration.
> >>>>
> >>>> Are their any objections to me checking this in? I’ll be doing the
> commit at around noon Pacific Daylight Time if I don’t hear any.
> >>>>
> >>>> Ralph
> >>>>
> >>>>
> >>>>
> >>>> On Jan 25, 2014, at 7:08 AM, Ralph Goers <ralph.go...@dslextreme.com>
> wrote:
> >>>>
> >>>>> I am working on the implementation of custom levels now. I should
> have it done today.
> >>>>>
> >>>>> Ralph
> >>>>>
> >>>>> On Jan 24, 2014, at 7:07 PM, Remko Popma <remko.po...@gmail.com>
> wrote:
> >>>>>
> >>>>>> What is the best way to make progress on the custom levels
> implementation?
> >>>>>>
> >>>>>> Do we re-open LOG4J-41 or start a fresh Jira ticket? For
> implementation ideas, do we attach files to Jira, or create a branch?
> >>>>>>
> >>>>>> Remko
> >>>>>>
> >>>>>> On Saturday, January 25, 2014, Gary Gregory <garydgreg...@gmail.com>
> wrote:
> >>>>>> On Fri, Jan 24, 2014 at 11:48 AM, Remko Popma <
> remko.po...@gmail.com> wrote:
> >>>>>> Gary,
> >>>>>>
> >>>>>> The hard-coded levels were proposed because it seemed that the
> extensible enum idea raised by Nick was not going to be accepted.
> >>>>>> My original position was that Markers could fulfill the requirement
> but Nick and yourself made it clear that this was not satisfactory.
> >>>>>>
> >>>>>> With extensible enums and markers off the table it seemed that the
> hard-coded levels was the only alternative, and discussion ensued about
> what these levels should be called and what strength they should have.
> >>>>>>
> >>>>>> During this discussion, several people, including me, repeatedly
> expressed strong reservations about adding pre-defined levels, but by this
> time I think people were thinking there was no alternative.
> >>>>>>
> >>>>>> It looked like we were getting stuck, with half the group moving in
> one direction ("add pre-defined levels!") and the other half wanting to
> move in another direction ("don't add pre-defined levels!"). I asked that
> we re-reviewed our assumptions and try to reach a solution that would
> satisfy all users.
> >>>>>>
> >>>>>> We then decided to explore the option of using extensible enums
> again. This is still ongoing, but I haven't seen anyone arguing against
> this idea since we started this thread.
> >>>>>>
> >>>>>> Hard-coded levels and the extensible enum are different solutions
> to the same problem.
> >>>>>>
> >>>>>> Hello All:
> >>>>>>
> >>>>>> Absolutely not. See my DEFCON example.
> >>>>>> Talking about an "extensible enum" is mixing design and
> implementation, we are talking about 'custom' and/or 'extensible' levels.
> >>>>>> Custom/Extensible levels can be designed to serve one or all of:
> >>>>>>
> >>>>>> - Allow inserting custom levels between built-in levels.
> >>>>>> - Allow for domain specific levels outside of the concept of
> built-in levels, the DEFCON example.
> >>>>>> - Should the custom levels themselves be extensible?
> >>>>>>
> >>>>>> Gary
> >>>>>>
> >>>>>> The extensible enum solution satisfies all of us who are opposed to
> adding pre-defined levels, while also satisfying the original requirement
> raised by Nick and yourself. Frankly I don't understand why you would still
> want the pre-defined levels.
> >>>>>>
> >>>>>> Remko
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> On Sat, Jan 25, 2014 at 12:53 AM, Gary Gregory <
> garydgreg...@gmail.com> wrote:
> >>>>>> On Thu, Jan 23, 2014 at 10:45 PM, Remko Popma <
> remko.po...@gmail.com> wrote:
> >>>>>> Gary,
> >>>>>>
> >>>>>> I think that's a very cool idea!
> >>>>>> Much more flexible, powerful and elegant than pre-defined levels
> could ever be.
> >>>>>>
> >>>>>> As I wrote: "I am discussing custom levels here with the
> understanding that this is a separate topic from what the built-in levels
> are."
> >>>>>>
> >>>>>> I'm not sure why you want to make the features mutually exclusive.
> (Some) others agree that these are different features.
> >>>>>>
> >>>>>> I see two topics:
> >>>>>>
> >>>>>> - What are the default levels for a 21st century logging framework.
> Do we simply blindly copy Log4j 1? Or do we look at frameworks from
> different languages and platforms for inspiration?
> >>>>>> - How (not if, I think we all agree) should we allow for custom
> levels.
> >>>>>>
> >>>>>> Gary
> >>>>>>
> >>>>>> It definitely makes sense to design the extensible enum with this
> potential usage in mind.
> >>>>>>
> >>>>>> Remko
> >>>>>>
> >>>>>>
> >>>>>> On Friday, January 24, 2014, Gary Gregory <garydgreg...@gmail.com>
> wrote:
> >>>>>> I am discussing custom levels here with the understanding that this
> is a separate topic from what the built-in levels are. Here is how I
> convinced myself that custom levels are a “good thing”.
> >>>>>>
> >>>>>> No matter which built-in levels exits, I may want custom levels.
> For example, I want my app to use the following levels DEFCON1, DEFCON2,
> DEFCON3, DEFCON4, and DEFCON5. This might be for one part of my app or a
> whole subsystem, no matter, I want to use the built-in levels in addition
> to the DEFCON levels. It is worth mentioning that if I want that feature
> only as a user, I can “skin” levels in a layout and assign any label to the
> built-in levels. If I am also a developer, I want to use DEFCON levels in
> the source code.
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> At first, my code might look like:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> logger.log(DefconLevels.DEFCON5, “All is quiet”);
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> Let’s put aside for now the type of DefconLevels.DEFCON* objects. I
> am a user, and I care about my call sites.
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> What I really want of course is to write:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> defconLogger.defcon5(“All is quiet”)
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> Therefore, I argue that for any “serious” use of a custom level, I
> will wrap a Logger in a custom logger class providing call-site friendly
> methods like defcon5(String).
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> So now, as a developer, all I care about is DefConLogger. It might
> wrap (or subclass) the Log4J Logger, who knows. The implementation of
> DefConLogger is not important to the developer (all I care is that the
> class has ‘defconN’ method) but it is important to the configuration
> author. This tells me that as a developer I do not care how DefConLogger is
> implemented, with custom levels, markers, or elves. However, as
> configuration author, I also want to use DEFCON level just like the
> built-in levels.
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> The configuration code co
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> --
> >>>>>> E-Mail: garydgreg...@gmail.com | ggreg...@apache.org
> >>>>>> Java Persistence with Hibernate, Second Edition
> >>>>>> JUnit in Action, Second Edition
> >>>>>> Spring Batch in Action
> >>>>>> Blog: http://garygregory.wordpress.com
> >>>>>> Home: http://garygregory.com/
> >>>>>> Tweet! http://twitter.com/GaryGregory
> >>>>>
> >>>>
> >>>
> >>
> >>
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--
Matt Sicker <boa...@gmail.com>
