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From Pavel Kovalenko <jokse...@gmail.com>
Subject Re: Coding guidelines. Useless JavaDoc comments.
Date Thu, 08 Aug 2019 15:34:02 GMT
I can agree that some part of javadocs we have is useless. It relates to
DTOs, getters/setters without side-effects, short self-descriptive methods.
In an ideal world, proper modularization of architecture, leading to
KISS/SOLID/DRY/etc. principles, writing self-documented code should result
in javadocs disappearing, as they become not needed.
We live in a not ideal world. We don't have good architecture and can't
always lead to mentioned principles, because we need sometimes sacrifice
readability for optimization, fixing a critical bug, etc.
I think that API of our core internal things like PageMemory, WAL, all
existing managers and processors should be as well documented as possible.
If a developer uses some module / manager / processor without looking
inside, reading the only description of public methods, it's a good sign
that this part of the functionality is well documented.
Internal implementation should be also clear for a developer who likes to
make a change inside it. Every optimization, avoiding race-condition, not
obvious thing and especially crutch must be documented as detailed as
possible.
Documentation should be a result of a proper code review. If a reviewer has
questions regarding any code line it should be either refactored to make
this thing obvious or well documented.
If a class or method is self-documented and obvious there is no need to
document it anyway.
if each person takes the code review as seriously as possible,
documentation and code will be better automatically.
Mandatory documentation in places where it's really not needed looks like a
burden. A developer will avoid write it properly everywhere or do it "just
for check" and this will influence on documentation with the negative side.
Flexible approach with mandatory / optional javadocs with good code review
will result in readability improvement overall.


чт, 8 авг. 2019 г. в 17:52, Maxim Muzafarov <maxmuzaf@gmail.com>:

> Ivan,
>
> It is not a problem to check Javadocs at the moment code syle checking
> performed, but do we really need this? And the human-factor you
> mentioned above is also related to the `self-descriptive` names. I
> assume, that someone now is desiring to use single-letter variables
> and single-letter class names to save space an time. We will always
> have such an opinion race.
>
> I'd prefer to leave the current situation with Javadoc as it is and
> just to ask to apply the patch [1][2]. Can you? :-)
>
> [1] https://issues.apache.org/jira/browse/IGNITE-12051
> [2] https://github.com/apache/ignite/pull/6760
>
> On Thu, 8 Aug 2019 at 17:24, Павлухин Иван <vololo100@gmail.com> wrote:
> >
> > 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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