* move `Future[T]` into its own module along with some basic accessors
* mark all fields internal, exposing only read-only versions under the
old names
* introduce `init`/`completed`/etc as a way of creating a future (vs
newFuture)
* introduce `LocationKind` for `SrcLoc` access
* don't expose `FutureList` unless future tracking is enabled
* introduce `chronosStrictFutureAccess` which controls a number of
additional `Defect` being raised when accessing Future fields in the
wrong state - this will become true in a future version
In this version, `Future[T]` backwards compatibility code remains in
`asyncfutures2` meaning that if only `chronos/futures` is imported, only
"new" API is available.
This branch is a refinement / less invasive / minimal version of
https://github.com/status-im/nim-chronos/pull/373.
* Avoid `FutureContinue` bloat by moving type punning into iterator
(which is typed anyway)
* clear closure iterator from future when iteration is done also on
cancellation / exception
* remove some redundant local variables in `await`
* document `futureContinue` flow
* FutureState.Finished -> FutureState.Completed (to avoid name clash
with `proc finished` which means not-pending)
* deprecate `done` - to avoid additional confusion over completed vs
finished
* remove ad leftovers in stack trace formatting
* avoid some generic bloat
* avoid unnecessary allocations in `race`/`one`
This PR moves all compile-time configuration to a single module,
simplifying documentation and access to these features.
Upcomfing features may be enabled either individually, or through a new
`chronosPreviewV4` catch-all designed to allow code to be prepared for
increased strictness in future chronos releases.
`-d:chronosDebug` may be used to enable the existing debugging helpers
together.
* Change Future identifier type from `int` to `uint64`.
* Fix compilation error and tests.
* Add integer overflow test, to avoid confusion with next Nim versions, we expect that unsigned integers do not raise any exceptions if overflow happens.
* Switch from `uint64` to `uint` type.
* Add `uint` overflow tests.
* exception tracking
This PR adds minimal exception tracking to chronos, moving the goalpost
one step further.
In particular, it becomes invalid to raise exceptions from `callSoon`
callbacks: this is critical for writing correct error handling because
there's no reasonable way that a user of chronos can possibly _reason_
about exceptions coming out of there: the event loop will be in an
indeterminite state when the loop is executing an _random_ callback.
As expected, there are several issues in the error handling of chronos:
in particular, it will end up in an inconsistent internal state whenever
the selector loop operations fail, because the internal state update
functions are not written in an exception-safe way. This PR turns this
into a Defect, which probably is not the optimal way of handling things
- expect more work to be done here.
Some API have no way of reporting back errors to callers - for example,
when something fails in the accept loop, there's not much it can do, and
no way to report it back to the user of the API - this has been fixed
with the new accept flow - the old one should be deprecated.
Finally, there is information loss in the API: in composite operations
like `poll` and `waitFor` there's no way to differentiate internal
errors from user-level errors originating from callbacks.
* store `CatchableError` in future
* annotate proc's with correct raises information
* `selectors2` to avoid non-CatchableError IOSelectorsException
* `$` should never raise
* remove unnecessary gcsafe annotations
* fix exceptions leaking out of timer waits
* fix some imports
* functions must signal raising the union of all exceptions across all
platforms to enable cross-platform code
* switch to unittest2
* add `selectors2` which supercedes the std library version and fixes
several exception handling issues in there
* fixes
* docs, platform-independent eh specifiers for some functions
* add feature flag for strict exception mode
also bump version to 3.0.0 - _most_ existing code should be compatible
with this version of exception handling but some things might need
fixing - callbacks, existing raises specifications etc.
* fix AsyncCheck for non-void T
it seems that due to a naming conflict from asyncdispatch, callSoon is
deduced to raise exceptions even if it doesn't in modules that import
both, even indirectly - this patch randomly works around the issue with
some more overloads
* Fix cancellation behavior.
Fix some compilation warnings.
* Fix cancelAndWait() and add proper documentation.
* Add completed(Future) and done(Future) calls to check if Future[T] completed without an error.
* Add stepsAsync() and tests.
* Fix comments.
* Fix new primitive comment, to avoid usage for task switches.
* release callback memory early
this fixes a memory leak where a deleted callback may keep references
alive until the future is finished.
In particular, when using helpers like `or` which try to remove
themselves from the callback list when a dependent future is completed,
create a reference chain between all futures in the expression - in the
pathological case where one of the futures is completes only rarely (for
example a timeout or a cancellation task), the buildup will be
significant.
* Removing unnecessary asserts, and place comments instead.
This reverts commit e45ef32b5b.
Metrics implemented this way, with a lock inside the otherwise tight
event loop are not consistent with the chronos architecture that for
good or bad uses thread local variables to avoid them - the solution
does not have rough consensus behind it, and other avenues should be
explored for this generally useful functionality.
This reverts commit d0a17d551f.
Moving CancelledError outside of the established Nim hierarchy is
not a solution that has rough consensus and has an unknown impact
on compatibility with otherwise correctly implemented cancellation
code (for example when `CatchableError` is caught, cleanup is done,
then the exception is reraised). Further, this breaks the established
convention in the Nim community that Exception should not be inherited
from, complicating compatibility with future Nim versions that may
enforce this more strongly.
This reverts commit baf33f04ea.
This change hides exceptions that should be handled explicitly -
asyncCheck is a debugging tool that should only be used in
exception-free situations (indeed, to fail when the operation
unexpectedly raises). There is no rough consensus behind this
change.
The cancellation process has a very complicated control flow, split over
different files and hidden by macros. These comments should help shed a
light on this madness.
* Make Future tracking optional via -d:chronosDutureTracking compilation flag.
* Stack traces is now optional, use -d:chronosStackTraces.
* Fix mistypes and add test for chronosStackTrace option.
Jacek Sieka
Eugene Kabanov
Tanguy
Ștefan Talpalaru
Zahary Karadjov
Yuriy Glukhov