I've create the ticket for implementing this [1]
[1] https://issues.apache.org/jira/browse/IGNITE-14611
пт, 16 апр. 2021 г. в 16:30, Alexei Scherbakov <alexey.scherbak...@gmail.com
>:
>
>
> чт, 15 апр. 2021 г. в 18:21, Andrey Mashenkov <andrey.mashen...@gmail.com
> >:
>
>> Hi Alexey,
>> I like the idea.
>>
>> 1.
>>
>> > TBL-0001 is a *string representation* of the error. It is built from 2
>> > byte scope id (mapped to name TBL) and 2 byte number (0001). Both
>> > internally packed in int. No any kind of parsing will be necessary to
>> read
>> > scope/category.
>>
>> I think Alexey mean if it will be possible to make smth like that
>>
>> catch (IgniteException e) {
>> if (e.getScope() == "TBL" && e.getCode() == 1234)
>> continue; // E.g. retry my TX
>> }
>>
>> It looks useful to me.
>>
>
> I have in mind something like this:
>
> public class IgniteException extends RuntimeException {
> private int errorCode;
>
> public IgniteException(ErrorScope scope, int code, String message,
> Throwable cause) {
> super(message, cause);
> this.errorCode = make(scope, code);
> }
>
> public boolean matches(ErrorScope scope, int code) {
> return errorCode == make(scope, code);
> }
>
> private int make(ErrorScope scope, int code) {
> return ((scope.ordinal() << 16) | code);
> }
>
> public ErrorScope scope() {
> return ErrorScope.values()[errorCode >> 16];
> }
>
> public int code() {
> return 0xFFFF & errorCode;
> }
>
> public static void main(String[] args) {
> IgniteException e = new IgniteException(ErrorScope.RAFT, 1,
> "test", null);
>
> System.out.println(e.matches(ErrorScope.RAFT, 2));
> System.out.println(e.scope());
> System.out.println(e.code());
>
> try {
> throw e;
> }
> catch (IgniteException ee) {
> System.out.println(ee.matches(ErrorScope.RAFT, 1));
> }
> }
> }
>
>
>>
>> 2. How you see a cross-module exception throwing?
>> Assume, user call -> module A, which recursively call -> module B, which
>> fails.
>> So, module A component calls a module B component and got an Exception
>> with
>> "B-1234" exception.
>> Module A do not expect any exception here and doesn't take care of "B-xxx"
>> error codes, but only "A-yyyy.
>> Should it rethrow exception with "A-unknown" (maybe "UNK-0001") code
>> or reuse "B-xxxx" code with the own message, pointing original exception
>> as
>> a cause for both cases?
>>
>> The first approach may looks confusing, while the second one produces too
>> many "UNK-" codes.
>> What code should get the user in that case?
>>
>>
>>
> The method should always report root cause, in your example it will be
> B-xxxx, no matter which module API is called.
>
>
>>
>>
>>
>> On Thu, Apr 15, 2021 at 5:36 PM Alexei Scherbakov <
>> alexey.scherbak...@gmail.com> wrote:
>>
>> > чт, 15 апр. 2021 г. в 14:26, Ilya Kasnacheev <ilya.kasnach...@gmail.com
>> >:
>> >
>> > > Hello!
>> > >
>> > > > All public methods throw only unchecked
>> > > org.apache.ignite.lang.IgniteException containing aforementioned
>> fields.
>> > > > Each public method must have a section in the javadoc with a list of
>> > all
>> > > possible error codes for this method.
>> > >
>> > > I don't think this is feasible at all.
>> > > Imagine javadoc for cache.get() method featuring three pages of
>> possible
>> > > error codes thrown by this method.
>> > >
>> >
>> > Of course there is no need to write 3 pages of error codes, this makes
>> no
>> > sense.
>> > I think we can use error ranges here, or, probably, document most
>> important
>> > error scenarios.
>> > The point here is to try to document errors as much as possible.
>> >
>> >
>> > > Also, updated every two weeks to account for changes in
>> > > underlying mechanisms.
>> > >
>> > > There is still a confusion between "error code for any error in logs"
>> and
>> > > "error code for any pair of method & exception". Which one are we
>> > > discussing really?
>> > >
>> > > This is impossible to track or test, but is susceptible for common
>> > > error-hiding antipattern where all exceptions are caught in
>> cache.get()
>> > and
>> > > discarded, and instead a brand new CH-0001 "error in cache.get()" is
>> > thrown
>> > > to the user.
>> > >
>> > > Which is certainly not something that anybody wants.
>> > >
>> >
>> > Certainly not. We are talking here about root cause - what is exactly
>> the
>> > reason for method call failure.
>> >
>> >
>> > >
>> > > Regards,
>> > > --
>> > > Ilya Kasnacheev
>> > >
>> > >
>> > > чт, 15 апр. 2021 г. в 13:03, Vladislav Pyatkov <vldpyat...@gmail.com
>> >:
>> > >
>> > > > Hi Alexei,
>> > > >
>> > > > > Each public method *must *have a section in the javadoc with a
>> list
>> > of
>> > > > all possible error codes for this method.
>> > > >
>> > > > I consider it is redundant, because any public exception can be
>> thrown
>> > > from
>> > > > public API.
>> > > > If it not happens today, it may change tomorrow: one will be
>> removed,
>> > > > another one will be added.
>> > > >
>> > > > >Nested exceptions are not forbidden to use. They can provide
>> > additional
>> > > > details on the error for debug purposes
>> > > >
>> > > > I see another issue, which is in the Ignite 2.x, but not attend
>> here.
>> > We
>> > > > can have a deep nested exception and use it for handling.
>> > > > In the result, all time when we are handling an exception we use
>> > > > pattern like this:
>> > > > try{
>> > > > ...
>> > > > }
>> > > > catch (Exception e) {
>> > > > if (X.hasCause(e, TimeoutException.class))
>> > > > throw e;
>> > > >
>> > > > if (X.hasCause(e, ConnectException.class, EOFException.class))
>> > > > continue;
>> > > >
>> > > > if (X.hasCause(e, InterruptedException.class))
>> > > > return false;
>> > > > }
>> > > >
>> > > > If we have a pant to make only one exception to the client side, we
>> can
>> > > > also do it for an internal exception.
>> > > >
>> > > > On Wed, Apr 14, 2021 at 11:42 AM Alexei Scherbakov <
>> > > > alexey.scherbak...@gmail.com> wrote:
>> > > >
>> > > > > Alexey,
>> > > > >
>> > > > > ср, 14 апр. 2021 г. в 01:52, Alexey Kukushkin <
>> > > kukushkinale...@gmail.com
>> > > > >:
>> > > > >
>> > > > > > Just some points looking questionable to me, although I realize
>> the
>> > > > error
>> > > > > > handling style may be very opinionated:
>> > > > > >
>> > > > > > - Would it make sense splitting the proposed composite error
>> > code
>> > > > > > (TBL-0001) into separate numeric code (0001) and
>> scope/category
>> > > > > ("TBL")
>> > > > > > to
>> > > > > > avoid parsing the code when an error handler needs to analyze
>> > only
>> > > > the
>> > > > > > category or the code?
>> > > > > >
>> > > > >
>> > > > > TBL-0001 is a *string representation* of the error. It is built
>> > from
>> > > 2
>> > > > > byte scope id (mapped to name TBL) and 2 byte number (0001). Both
>> > > > > internally packed in int. No any kind of parsing will be
>> necessary to
>> > > > read
>> > > > > scope/category.
>> > > > >
>> > > > >
>> > > > > > - "*The cause - short string description of an issue,
>> readable
>> > by
>> > > > > > user.*".
>> > > > > > This terminology sounds confusing to me since that "cause"
>> > sounds
>> > > > like
>> > > > > > Java
>> > > > > > Throwable's Message to me and the "Cause" is a lower level
>> > > > exception.
>> > > > > >
>> > > > >
>> > > > > The string describes the cause of error, so the name. I'm ok to
>> > rename
>> > > it
>> > > > > to a message. It will be stored in IgniteException.message field
>> > > anyway.
>> > > > >
>> > > > >
>> > > > > > - "*The action - steps for a user to resolve error...*". The
>> > > action
>> > > > is
>> > > > > > very important but do we want to make it part of the
>> > > > IgniteException?
>> > > > > I
>> > > > > > do
>> > > > > > not think the recovery action text should be part of the
>> > > exception.
>> > > > > > IgniteException may include a URL pointing to the
>> corresponding
>> > > > > > documentation - this is discussable.
>> > > > > >
>> > > > >
>> > > > > This will not be the part of the exception. A user should visit
>> the
>> > > > > documentation page and read the action section by corresponding
>> error
>> > > > code.
>> > > > >
>> > > > >
>> > > > > > - "*All public methods throw only unchecked
>> IgniteException*" -
>> > I
>> > > > > assume
>> > > > > > we still respect JCache specification and prefer using
>> standard
>> > > Java
>> > > > > > exception to signal about invalid parameters.
>> > > > > >
>> > > > >
>> > > > > Using standard java exceptions whenever possible makes sense.
>> > > > >
>> > > > >
>> > > > > > - Why we do not follow the "classic" structured exception
>> > handling
>> > > > > > practices in Ignite:
>> > > > > >
>> > > > >
>> > > > > Ignite 3 will be multi language, and other languages use other
>> error
>> > > > > processing models. SQL for example uses error codes.
>> > > > > The single exception approach simplifies and unifies error
>> handling
>> > > > across
>> > > > > platforms for me.
>> > > > >
>> > > > >
>> > > > > > - Why do we not allow using checked exceptions? It seems
>> to
>> > me
>> > > > > > sometimes forcing the user to handle an error serves as a
>> > hint
>> > > > and
>> > > > > > thus
>> > > > > > improves usability. For example, handling an
>> > > > optimistic/pessimistic
>> > > > > > transaction conflict/deadlock. Or handling a timeout for
>> > > > operations
>> > > > > > with
>> > > > > > timeouts.
>> > > > > >
>> > > > >
>> > > > > A valid point. Checked exceptions must be used for whose methods,
>> > where
>> > > > > error handling is enforced, for example tx optimistic failure.
>> > > > > Such errors will also have corresponding error codes.
>> > > > >
>> > > > >
>> > > > > > - Why single public IgniteException and no exception
>> > hierarchy?
>> > > > > Java
>> > > > > > is optimized for structured exception handling instead of
>> > using
>> > > > > > IF-ELSE to
>> > > > > > analyze the codes.
>> > > > > >
>> > > > >
>> > > > > Exception hierarchy is not required when using error codes and
>> > > applicable
>> > > > > only to java API, so I would avoid spending efforts on it.
>> > > > >
>> > > > >
>> > > > > > - Why no nested exceptions? Sometimes an error handler is
>> > > > > interested
>> > > > > > only in high level exceptions (like Invalid Configuration)
>> > and
>> > > > > > sometimes
>> > > > > > details are needed (like specific configuration parser
>> > > > exceptions).
>> > > > > >
>> > > > >
>> > > > > Nested exceptions are not forbidden to use. They can provide
>> > additional
>> > > > > details on the error for debug purposes, but not strictly
>> required,
>> > > > because
>> > > > > error code + message should provide enough information to the
>> user.
>> > > > >
>> > > > >
>> > > > > > - For async methods returning a Future we may have a
>> universal
>> > > rule
>> > > > on
>> > > > > > how to handle exceptions. For example, we may specify that
>> any
>> > > async
>> > > > > > method
>> > > > > > can throw only invalid argument exceptions. All other errors
>> are
>> > > > > > reported
>> > > > > > via the exceptionally(IgniteException -> {}) callback even if
>> > the
>> > > > > async
>> > > > > > method was executed synchronously.
>> > > > > >
>> > > > >
>> > > > > This is ok to me.
>> > > > >
>> > > > >
>> > > > > >
>> > > > > >
>> > > > > > вт, 13 апр. 2021 г. в 12:08, Alexei Scherbakov <
>> > > > > > alexey.scherbak...@gmail.com
>> > > > > > >:
>> > > > > >
>> > > > > > > Igniters,
>> > > > > > >
>> > > > > > > I would like to start the discussion about error handling in
>> > > Ignite 3
>> > > > > and
>> > > > > > > how we can improve it compared to Ignite 2.
>> > > > > > >
>> > > > > > > The error handling in Ignite 2 was not very good because of
>> > generic
>> > > > > > > CacheException thrown on almost any occasion, having deeply
>> > nested
>> > > > root
>> > > > > > > cause and often containing no useful information on further
>> steps
>> > > to
>> > > > > fix
>> > > > > > > the issue.
>> > > > > > >
>> > > > > > > I aim to fix it by introducing some rules on error handling.
>> > > > > > >
>> > > > > > > *Public exception structure.*
>> > > > > > >
>> > > > > > > A public exception must have an error code, a cause, and an
>> > action.
>> > > > > > >
>> > > > > > > * The code - the combination of 2 byte scope id and 2 byte
>> error
>> > > > number
>> > > > > > > within the module. This allows up to 2^16 errors for each
>> scope,
>> > > > which
>> > > > > > > should be enough. The error code string representation can
>> look
>> > > like
>> > > > > > > RFT-0001 or TBL-0001
>> > > > > > > * The cause - short string description of an issue, readable
>> by
>> > > user.
>> > > > > > This
>> > > > > > > can have dynamic parameters depending on the error type for
>> > better
>> > > > user
>> > > > > > > experience, like "Can't write a snapshot, no space left on
>> device
>> > > > {0}"
>> > > > > > > * The action - steps for a user to resolve error situation
>> > > described
>> > > > in
>> > > > > > the
>> > > > > > > documentation in the corresponding error section, for example
>> > > "Clean
>> > > > up
>> > > > > > > disk space and retry the operation".
>> > > > > > >
>> > > > > > > Common errors should have their own scope, for example
>> IGN-0001
>> > > > > > >
>> > > > > > > All public methods throw only unchecked
>> > > > > > > org.apache.ignite.lang.IgniteException containing
>> aforementioned
>> > > > > fields.
>> > > > > > > Each public method must have a section in the javadoc with a
>> list
>> > > of
>> > > > > all
>> > > > > > > possible error codes for this method.
>> > > > > > >
>> > > > > > > A good example with similar structure can be found here [1]
>> > > > > > >
>> > > > > > > *Async timeouts.*
>> > > > > > >
>> > > > > > > Because almost all API methods in Ignite 3 are async, they all
>> > will
>> > > > > have
>> > > > > > a
>> > > > > > > configurable default timeout and can complete with timeout
>> error
>> > > if a
>> > > > > > > computation is not finished in time, for example if a response
>> > has
>> > > > not
>> > > > > > been
>> > > > > > > yet received.
>> > > > > > > I suggest to complete the async op future with
>> TimeoutException
>> > in
>> > > > this
>> > > > > > > case to make it on par with synchronous execution using
>> > future.get,
>> > > > > which
>> > > > > > > will throw java.util.concurrent.TimeoutException on timeout.
>> > > > > > > For reference, see
>> > java.util.concurrent.CompletableFuture#orTimeout
>> > > > > > > No special error code should be used for this scenario.
>> > > > > > >
>> > > > > > > *Internal exceptions hierarchy.*
>> > > > > > >
>> > > > > > > All internal exceptions should extend
>> > > > > > > org.apache.ignite.internal.lang.IgniteInternalException for
>> > checked
>> > > > > > > exceptions and
>> > > > > > > org.apache.ignite.internal.lang.IgniteInternalCheckedException
>> > for
>> > > > > > > unchecked exceptions.
>> > > > > > >
>> > > > > > > Thoughts ?
>> > > > > > >
>> > > > > > > [1]
>> > > > https://docs.oracle.com/cd/B10501_01/server.920/a96525/preface.htm
>> > > > > > >
>> > > > > > > --
>> > > > > > >
>> > > > > > > Best regards,
>> > > > > > > Alexei Scherbakov
>> > > > > > >
>> > > > > >
>> > > > > >
>> > > > > > --
>> > > > > > Best regards,
>> > > > > > Alexey
>> > > > > >
>> > > > >
>> > > > >
>> > > > > --
>> > > > >
>> > > > > Best regards,
>> > > > > Alexei Scherbakov
>> > > > >
>> > > >
>> > > >
>> > > > --
>> > > > Vladislav Pyatkov
>> > > >
>> > >
>> >
>> >
>> > --
>> >
>> > Best regards,
>> > Alexei Scherbakov
>> >
>>
>>
>> --
>> Best regards,
>> Andrey V. Mashenkov
>>
>
>
> --
>
> Best regards,
> Alexei Scherbakov
>
--
Best regards,
Alexei Scherbakov
