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Flushing channels on destroy #78

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Flushing channels on destroy #78

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16f5c8d
add channel flushing on destroy, add tryRecv with Option[T] result
darkestpigeon Oct 17, 2024
1410787
removed tryRecv with Option[T]
darkestpigeon Oct 17, 2024
2d1f860
fixed a bug (flushing was done without checking the refcount)
darkestpigeon Oct 22, 2024
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23 changes: 22 additions & 1 deletion threading/channels.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,7 @@ runnableExamples("--threads:on --gc:orc"):
when not (defined(gcArc) or defined(gcOrc) or defined(gcAtomicArc) or defined(nimdoc)):
{.error: "This module requires one of --mm:arc / --mm:atomicArc / --mm:orc compilation flags".}

import std/[locks, isolation, atomics]
import std/[locks, isolation, atomics, options]
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@Araq Araq Oct 17, 2024

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Nah. I don't like options and nothing about this new API is hardly any better than the old one:

var x: T
if tryRecv(chan, x): ...

vs:

let x = tryRecv(chan) 
if x.isSome: ...

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@darkestpigeon darkestpigeon Oct 17, 2024

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fair enough


# Channel
# ------------------------------------------------------------------------------
Expand Down Expand Up @@ -256,10 +256,15 @@ type
Chan*[T] = object ## Typed channel
d: ChannelRaw

proc tryRecv*[T](c: Chan[T]): Option[T] {.inline, raises: [].}

template frees(c) =
if c.d != nil:
# this `fetchSub` returns current val then subs
# so count == 0 means we're the last
while true:
if c.tryRecv().isNone:
break
if c.d.atomicCounter.fetchSub(1, moAcquireRelease) == 0:
freeChannel(c.d)

Expand Down Expand Up @@ -343,6 +348,22 @@ proc tryRecv*[T](c: Chan[T], dst: var T): bool {.inline.} =
## Returns `false` and does not change `dist` if no message was received.
channelReceive(c.d, dst.addr, sizeof(T), false)

proc tryRecv*[T](c: Chan[T]): Option[T] {.inline.} =
## Tries to receive a message from the channel `c`.
##
## Doesn't block waiting for messages in the channel to become available.
## Instead returns after an attempt to receive a message was made.
##
## .. warning:: In high-concurrency situations, consider using an exponential
## backoff strategy to reduce contention and improve the success rate of
## operations.
var dst: T
let dataAvailable = tryRecv(c, dst)
if dataAvailable:
result = some(dst)
else:
result = none(T)

proc send*[T](c: Chan[T], src: sink Isolated[T]) {.inline.} =
## Sends the message `src` to the channel `c`.
## This blocks the sending thread until `src` was successfully sent.
Expand Down