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From Павлухин Иван <vololo...@gmail.com>
Subject Re: Coding guidelines. Useless JavaDoc comments.
Date Thu, 08 Aug 2019 14:24:28 GMT
Maxim,

My main concern here is a human factor. Humans are usually not so good
in keeping documentation always in sync with a code. Examples from an
actual PR:
/**
* @param nodeId The remote node id.
* @param channel The channel to notify listeners with.
*/
private void onChannelOpened0(UUID nodeId, GridIoMessage initMsg,
Channel channel)

First, there is a mismatch between number of parameters in javadoc and
code. Second, e.g. nodeId name can be made self-descriptive rmtNodeId
name.

Mandatory javadocs do not imply good javadocs. Good javadocs do not
imply javadocs for every method and field. For me, mandatory and good
javadocs are like communism. Sounds quite nice in theory, but not
feasible in practice.

чт, 8 авг. 2019 г. в 16:55, Denis Garus <garus.d.g@gmail.com>:
>
> Thank you, Maxim.
>
> >>On what we are trying to save by making Javadoc optional?
>
> Space and time.
>
> I doubt that we need a verbal description of what private method make.
> Why we need it if we just can read the code?
>
> Bright examples:
>
> /**
> * @param helper Helper to attach to kernal context.
> */
> private void addHelper(Object helper) {
>     ctx.addHelper(helper);
> }
>
> /**
> * Gets "on" or "off" string for given boolean value.
> *
> * @param b Boolean value to convert.
> * @return Result string.
> */
> private String onOff(boolean b) {
>     return b ? "on" : "off";
> }
>
> You have to support both code of method and their JavaDoc description, but
> it doesn't get any sake.
>
> >>Let's just help them to read the source code.
>
> But at the same time, public method IgniteKernal#start doesn't have any
> description except enumeration of attributes with apparent notes.
> Maybe to give it a verbal description needs one or two pages of the screen.
> Does it make sense?
>
> чт, 8 авг. 2019 г. в 15:41, Maxim Muzafarov <maxmuzaf@gmail.com>:
>
> > Igniters,
> >
> > I'm -1 with making Javadoc optional (except tests).
> >
> > Here is my patch [1] with PR [2] which fixes all the Javadoc comments
> > for the IgniteKernal class mentioned above. Please, take a look. The
> > review is very appreciated.
> >
> > On what we are trying to save by making Javadoc optional? In my humble
> > opinion - Javadoc comments are mostly concern users who debug the
> > Ignite when they have faced with some unhandled exception or related
> > to the community members with an average involvement (produces a few
> > small patches during the year) but not to the experienced one. Let's
> > just help them to read the source code.
> >
> > [1] https://issues.apache.org/jira/browse/IGNITE-12051
> > [2] https://github.com/apache/ignite/pull/6760
> >
> >
> >
> > On Wed, 7 Aug 2019 at 13:54, Andrey Kuznetsov <stkuzma@gmail.com> wrote:
> > >
> > > +1 for making javadoc comments optional.
> > >
> > > - Empty and tautological comments are kind of garbage that reduce
> > > readability.
> > > - It's better to leave the entity undocumented, than write
> > > unexpressive/misleading comment.
> > > - Even classes may not require javadocs, e.g. simple DTOs.
> > >
> > > ср, 7 авг. 2019 г., 13:39 Denis Garus <garus.d.g@gmail.com>:
> > >
> > > > Thx for feedback!
> > > >
> > > > >> we have to write proper javadoc for all production classes,
> > including
> > > > internal.
> > > >
> > > > Nikolay, I cannot agree with it.
> > > >
> > > > What should be the best comment for the next fields?
> > > > /** */
> > > > private static final long serialVersionUID = 0L;
> > > > or
> > > > /** */
> > > > @LoggerResource
> > > > private IgniteLogger log;
> > > >
> > > > There are more than 8000 lines of /** */ only at the ignite-core
> > module (do
> > > > not include tests).
> > > >
> > > > Any comments will be redundant and just noise. Obvious comment learns
> > > > readers skip all comments.
> > > >
> > > >
> > > > >> identical distance/padding/margin between fields in a class -
is
> > really
> > > > cool
> > > >
> > > > Vyacheslav, but we have a blank line between fields. Why is one blank
> > line
> > > > not enough?
> > > >
> > > > ср, 7 авг. 2019 г. в 12:58, Павлухин Иван <vololo100@gmail.com>:
> > > >
> > > > > Hi,
> > > > >
> > > > > Denis, thank you for starting this discussion!
> > > > >
> > > > > My opinion here is that having a good javadoc for every class and
> > > > > method is not feasible in the real world. I am quite curious to see
a
> > > > > non-trivial project which follows it. Also, all comments and javadocs
> > > > > are prone to become misleading when code changes (human factor).
In
> > my
> > > > > experience good method and variable names and clear code organization
> > > > > often are more helpful than javadocs.
> > > > >
> > > > > ср, 7 авг. 2019 г. в 12:49, Vyacheslav Daradur <daradurvs@gmail.com
> > >:
> > > > > >
> > > > > > I agree that useless comments look weird in the codebase.
> > > > > >
> > > > > > But, identical distance/padding/margin between fields in a class
-
> > is
> > > > > > really cool, and helps read the class very fast.
> > > > > >
> > > > > > On Wed, Aug 7, 2019 at 12:26 PM Nikolay Izhikov <
> > nizhikov@apache.org>
> > > > > wrote:
> > > > > > >
> > > > > > > Hello, Denis.
> > > > > > >
> > > > > > > Thanks for starting this discussion.
> > > > > > >
> > > > > > > I think we have to write proper javadoc for all production
> > classes,
> > > > > including internal.
> > > > > > > We should fix useless javadoc you provide.
> > > > > > > We should not accept patches without good javadocs.
> > > > > > >
> > > > > > > As for the tests, seems, we can make javadoc optional.
> > > > > > >
> > > > > > > What do you think?
> > > > > > >
> > > > > > >
> > > > > > > В Ср, 07/08/2019 в 11:41 +0300, Denis Garus пишет:
> > > > > > > > Igniters!
> > > > > > > >
> > > > > > > > I think it's time to change coding guidelines in part
of
> > JavaDoc
> > > > > comments
> > > > > > > > [1]:
> > > > > > > > > > Every method, field or initializer public,
private or
> > protected
> > > > > in
> > > > > > > >
> > > > > > > > top-level,
> > > > > > > > > > inner or anonymous type should have at least
minimal
> > Javadoc
> > > > > comments
> > > > > > > >
> > > > > > > > including
> > > > > > > > > > description and description of parameters
using @param,
> > @return
> > > > > and
> > > > > > > >
> > > > > > > > @throws Javadoc tags,
> > > > > > > > > > where applicable.
> > > > > > > >
> > > > > > > > Let's look at JavaDoc comments in the IgniteKernal
class:
> > > > > > > >
> > > > > > > > Why?
> > > > > > > >
> > > > > > > > /** */ - 15 matches.
> > > > > > > >
> > > > > > > > What can you get new from these comments?
> > > > > > > >
> > > > > > > > /** Periodic starvation check interval. */
> > > > > > > > private static final long PERIODIC_STARVATION_CHECK_FREQ
=
> > 1000 *
> > > > 30;
> > > > > > > >
> > > > > > > > /** Long jvm pause detector. */
> > > > > > > > private LongJVMPauseDetector longJVMPauseDetector;
> > > > > > > >
> > > > > > > > /** Scheduler. */
> > > > > > > >     private IgniteScheduler scheduler;
> > > > > > > >
> > > > > > > > /** Stop guard. */
> > > > > > > >     private final AtomicBoolean stopGuard = new
> > AtomicBoolean();
> > > > > > > >
> > > > > > > > /**
> > > > > > > >      * @param cfg Configuration to use.
> > > > > > > >      * @param utilityCachePool Utility cache pool.
> > > > > > > >      * @param execSvc Executor service.
> > > > > > > >      * @param sysExecSvc System executor service.
> > > > > > > >      * @param stripedExecSvc Striped executor.
> > > > > > > >      * @param p2pExecSvc P2P executor service.
> > > > > > > >      * @param mgmtExecSvc Management executor service.
> > > > > > > >      * @param igfsExecSvc IGFS executor service.
> > > > > > > >      * @param dataStreamExecSvc data stream executor
service.
> > > > > > > >      * @param restExecSvc Reset executor service.
> > > > > > > >      * @param affExecSvc Affinity executor service.
> > > > > > > >      * @param idxExecSvc Indexing executor service.
> > > > > > > >      * @param callbackExecSvc Callback executor service.
> > > > > > > >      * @param qryExecSvc Query executor service.
> > > > > > > >      * @param schemaExecSvc Schema executor service.
> > > > > > > >      * @param customExecSvcs Custom named executors.
> > > > > > > >      * @param errHnd Error handler to use for notification
> > about
> > > > > startup
> > > > > > > > problems.
> > > > > > > >      * @param workerRegistry Worker registry.
> > > > > > > >      * @param hnd Default uncaught exception handler
used by
> > thread
> > > > > pools.
> > > > > > > >      * @throws IgniteCheckedException Thrown in case
of any
> > errors.
> > > > > > > >      */
> > > > > > > >     public void start(
> > > > > > > >         final IgniteConfiguration cfg,
> > > > > > > >         ExecutorService utilityCachePool,
> > > > > > > >         final ExecutorService execSvc,
> > > > > > > >         final ExecutorService svcExecSvc,
> > > > > > > >         final ExecutorService sysExecSvc,
> > > > > > > >         final StripedExecutor stripedExecSvc,
> > > > > > > >         ExecutorService p2pExecSvc,
> > > > > > > >         ExecutorService mgmtExecSvc,
> > > > > > > >         ExecutorService igfsExecSvc,
> > > > > > > >         StripedExecutor dataStreamExecSvc,
> > > > > > > >         ExecutorService restExecSvc,
> > > > > > > >         ExecutorService affExecSvc,
> > > > > > > >         @Nullable ExecutorService idxExecSvc,
> > > > > > > >         IgniteStripedThreadPoolExecutor callbackExecSvc,
> > > > > > > >         ExecutorService qryExecSvc,
> > > > > > > >         ExecutorService schemaExecSvc,
> > > > > > > >         @Nullable final Map<String, ? extends ExecutorService>
> > > > > > > > customExecSvcs,
> > > > > > > >         GridAbsClosure errHnd,
> > > > > > > >         WorkersRegistry workerRegistry,
> > > > > > > >         Thread.UncaughtExceptionHandler hnd,
> > > > > > > >         TimeBag startTimer
> > > > > > > >     )
> > > > > > > >
> > > > > > > > These comments look ugly and useless, and that is
the main
> > class of
> > > > > core.
> > > > > > > > Why do they need us?
> > > > > > > > Let us change the coding guidelines in part of JavaDoc
> > comments:
> > > > > > > > Every method public API should have at least minimal
Javadoc
> > > > > comments,
> > > > > > > > including description and description of parameters
using
> > @param,
> > > > > @return,
> > > > > > > > and @throws Javadoc tags,
> > > > > > > > where applicable.
> > > > > > > > For internal API, JavaDoc comments should be optional.
It's up
> > to a
> > > > > > > > contributor or reviewer.
> > > > > > > >
> > > > > > > > What are you think?
> > > > > > > >
> > > > > > > > 1.
> > > > > > > >
> > > > >
> > > >
> > https://cwiki.apache.org/confluence/display/IGNITE/Coding+Guidelines#CodingGuidelines-JavadocComments
> > > > > >
> > > > > >
> > > > > >
> > > > > > --
> > > > > > Best Regards, Vyacheslav D.
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Best regards,
> > > > > Ivan Pavlukhin
> > > > >
> > > >
> >



-- 
Best regards,
Ivan Pavlukhin

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