167 lines
6.9 KiB
Nim
167 lines
6.9 KiB
Nim
## Compile-time configuration options for chronos that control the availability
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## of various strictness and debuggability options. In general, debug helpers
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## are enabled when `debug` is defined while strictness options are introduced
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## in transition periods leading up to a breaking release that starts enforcing
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## them and removes the option.
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##
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## `chronosPreviewV4` is a preview flag to enable v4 semantics - in particular,
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## it enables strict exception checking and disables parts of the deprecated
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## API and other changes being prepared for the upcoming release
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##
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## `chronosDebug` can be defined to enable several debugging helpers that come
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## with a runtime cost - it is recommeneded to not enable these in production
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## code.
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##
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## In this file we also declare feature flags starting with `chronosHas...` -
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## these constants are declared when a feature exists in a particular release -
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## each flag is declared as an integer starting at 0 during experimental
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## development, 1 when feature complete and higher numbers when significant
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## functionality has been added. If a feature ends up being removed (or changed
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## in a backwards-incompatible way), the feature flag will be removed or renamed
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## also - you can use `when declared(chronosHasXxx): when chronosHasXxx >= N:`
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## to require a particular version.
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const
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chronosHandleException* {.booldefine.}: bool = false
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## Remap `Exception` to `AsyncExceptionError` for all `async` functions.
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##
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## This modes provides backwards compatibility when using functions with
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## inaccurate `{.raises.}` effects such as unannotated forward declarations,
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## methods and `proc` types - it is recommened to annotate such code
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## explicitly as the `Exception` handling mode may introduce surprising
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## behavior in exception handlers, should `Exception` actually be raised.
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##
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## The setting provides the default for the per-function-based
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## `handleException` parameter which has precedence over this global setting.
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##
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## `Exception` handling may be removed in future chronos versions.
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chronosStrictFutureAccess* {.booldefine.}: bool = defined(chronosPreviewV4)
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chronosStackTrace* {.booldefine.}: bool = defined(chronosDebug)
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## Include stack traces in futures for creation and completion points
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chronosFutureId* {.booldefine.}: bool = defined(chronosDebug)
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## Generate a unique `id` for every future - when disabled, the address of
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## the future will be used instead
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chronosFutureTracking* {.booldefine.}: bool = defined(chronosDebug)
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## Keep track of all pending futures and allow iterating over them -
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## useful for detecting hung tasks
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chronosDumpAsync* {.booldefine.}: bool = defined(nimDumpAsync)
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## Print code generated by {.async.} transformation
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chronosProcShell* {.strdefine.}: string =
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when defined(windows):
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"cmd.exe"
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else:
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when defined(android):
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"/system/bin/sh"
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else:
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"/bin/sh"
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## Default shell binary path.
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##
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## The shell is used as command for command line when process started
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## using `AsyncProcessOption.EvalCommand` and API calls such as
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## ``execCommand(command)`` and ``execCommandEx(command)``.
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chronosEventsCount* {.intdefine.} = 64
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## Number of OS poll events retrieved by syscall (epoll, kqueue, poll).
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chronosInitialSize* {.intdefine.} = 64
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## Initial size of Selector[T]'s array of file descriptors.
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chronosEventEngine* {.strdefine.}: string =
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when defined(nimdoc):
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""
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elif defined(linux) and not(defined(android) or defined(emscripten)):
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"epoll"
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elif defined(macosx) or defined(macos) or defined(ios) or
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defined(freebsd) or defined(netbsd) or defined(openbsd) or
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defined(dragonfly):
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"kqueue"
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elif defined(android) or defined(emscripten):
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"poll"
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elif defined(posix):
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"poll"
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else:
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""
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## OS polling engine type which is going to be used by chronos.
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chronosHasRaises* = 0
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## raises effect support via `async: (raises: [])`
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chronosTransportDefaultBufferSize* {.intdefine.} = 16384
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## Default size of chronos transport internal buffer.
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chronosStreamDefaultBufferSize* {.intdefine.} = 16384
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## Default size of chronos async stream internal buffer.
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chronosTLSSessionCacheBufferSize* {.intdefine.} = 4096
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## Default size of chronos TLS Session cache's internal buffer.
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when defined(chronosStrictException):
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{.warning: "-d:chronosStrictException has been deprecated in favor of handleException".}
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# In chronos v3, this setting was used as the opposite of
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# `chronosHandleException` - the setting is deprecated to encourage
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# migration to the new mode.
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when defined(debug) or defined(chronosConfig):
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import std/macros
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static:
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hint("Chronos configuration:")
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template printOption(name: string, value: untyped) =
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hint(name & ": " & $value)
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printOption("chronosHandleException", chronosHandleException)
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printOption("chronosStackTrace", chronosStackTrace)
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printOption("chronosFutureId", chronosFutureId)
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printOption("chronosFutureTracking", chronosFutureTracking)
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printOption("chronosDumpAsync", chronosDumpAsync)
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printOption("chronosProcShell", chronosProcShell)
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printOption("chronosEventEngine", chronosEventEngine)
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printOption("chronosEventsCount", chronosEventsCount)
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printOption("chronosInitialSize", chronosInitialSize)
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printOption("chronosTransportDefaultBufferSize",
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chronosTransportDefaultBufferSize)
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printOption("chronosStreamDefaultBufferSize",
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chronosStreamDefaultBufferSize)
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printOption("chronosTLSSessionCacheBufferSize",
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chronosTLSSessionCacheBufferSize)
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# In nim 1.6, `sink` + local variable + `move` generates the best code for
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# moving a proc parameter into a closure - this only works for closure
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# procedures however - in closure iterators, the parameter is always copied
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# into the closure (!) meaning that non-raw `{.async.}` functions always carry
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# this overhead, sink or no. See usages of chronosMoveSink for examples.
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# In addition, we need to work around https://github.com/nim-lang/Nim/issues/22175
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# which has not been backported to 1.6.
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# Long story short, the workaround is not needed in non-raw {.async.} because
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# a copy of the literal is always made.
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# TODO review the above for 2.0 / 2.0+refc
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type
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SeqHeader = object
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length, reserved: int
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proc isLiteral(s: string): bool {.inline.} =
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when defined(gcOrc) or defined(gcArc):
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false
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else:
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s.len > 0 and (cast[ptr SeqHeader](s).reserved and (1 shl (sizeof(int) * 8 - 2))) != 0
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proc isLiteral[T](s: seq[T]): bool {.inline.} =
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when defined(gcOrc) or defined(gcArc):
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false
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else:
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s.len > 0 and (cast[ptr SeqHeader](s).reserved and (1 shl (sizeof(int) * 8 - 2))) != 0
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template chronosMoveSink*(val: auto): untyped =
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bind isLiteral
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when not (defined(gcOrc) or defined(gcArc)) and val is seq|string:
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if isLiteral(val):
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val
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else:
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move(val)
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else:
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move(val)
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