nim-chronos/chronos/threadsync.nim

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#
# Chronos multithreaded synchronization primitives
#
# (c) Copyright 2023-Present Status Research & Development GmbH
#
# Licensed under either of
# Apache License, version 2.0, (LICENSE-APACHEv2)
# MIT license (LICENSE-MIT)
## This module implements some core async thread synchronization primitives.
2023-11-13 09:56:19 +00:00
import results
import "."/[timer, asyncloop]
export results
{.push raises: [].}
const hasThreadSupport* = compileOption("threads")
when not(hasThreadSupport):
{.fatal: "Compile this program with threads enabled!".}
import "."/[osdefs, osutils, oserrno]
type
ThreadSignal* = object
when defined(windows):
event: HANDLE
elif defined(linux):
efd: AsyncFD
else:
rfd, wfd: AsyncFD
ThreadSignalPtr* = ptr ThreadSignal
proc new*(t: typedesc[ThreadSignalPtr]): Result[ThreadSignalPtr, string] =
## Create new ThreadSignal object.
let res = cast[ptr ThreadSignal](allocShared0(sizeof(ThreadSignal)))
when defined(windows):
var sa = getSecurityAttributes()
let event = osdefs.createEvent(addr sa, DWORD(0), DWORD(0), nil)
if event == HANDLE(0):
deallocShared(res)
return err(osErrorMsg(osLastError()))
res[] = ThreadSignal(event: event)
elif defined(linux):
let efd = eventfd(0, EFD_CLOEXEC or EFD_NONBLOCK)
if efd == -1:
deallocShared(res)
return err(osErrorMsg(osLastError()))
res[] = ThreadSignal(efd: AsyncFD(efd))
else:
var sockets: array[2, cint]
block:
let sres = socketpair(AF_UNIX, SOCK_DGRAM, 0, sockets)
if sres < 0:
deallocShared(res)
return err(osErrorMsg(osLastError()))
# MacOS do not have SOCK_NONBLOCK and SOCK_CLOEXEC, so we forced to use
# setDescriptorFlags() for every socket.
block:
let sres = setDescriptorFlags(sockets[0], true, true)
if sres.isErr():
discard closeFd(sockets[0])
discard closeFd(sockets[1])
deallocShared(res)
return err(osErrorMsg(sres.error))
block:
let sres = setDescriptorFlags(sockets[1], true, true)
if sres.isErr():
discard closeFd(sockets[0])
discard closeFd(sockets[1])
deallocShared(res)
return err(osErrorMsg(sres.error))
res[] = ThreadSignal(rfd: AsyncFD(sockets[0]), wfd: AsyncFD(sockets[1]))
ok(ThreadSignalPtr(res))
when not(defined(windows)):
type
WaitKind {.pure.} = enum
Read, Write
when defined(linux):
proc checkBusy(fd: cint): bool = false
else:
proc checkBusy(fd: cint): bool =
var data = 0'u64
let res = handleEintr(recv(SocketHandle(fd),
addr data, sizeof(uint64), MSG_PEEK))
if res == sizeof(uint64):
true
else:
false
func toTimeval(a: Duration): Timeval =
## Convert Duration ``a`` to ``Timeval`` object.
let nanos = a.nanoseconds
let m = nanos mod Second.nanoseconds()
Timeval(
tv_sec: Time(nanos div Second.nanoseconds()),
tv_usec: Suseconds(m div Microsecond.nanoseconds())
)
proc waitReady(fd: cint, kind: WaitKind,
timeout: Duration): Result[bool, OSErrorCode] =
var
tv: Timeval
fdset =
block:
var res: TFdSet
FD_ZERO(res)
FD_SET(SocketHandle(fd), res)
res
let
ptv =
if not(timeout.isInfinite()):
tv = timeout.toTimeval()
addr tv
else:
nil
nfd = cint(fd) + 1
res =
case kind
of WaitKind.Read:
handleEintr(select(nfd, addr fdset, nil, nil, ptv))
of WaitKind.Write:
handleEintr(select(nfd, nil, addr fdset, nil, ptv))
if res > 0:
ok(true)
elif res == 0:
ok(false)
else:
err(osLastError())
proc safeUnregisterAndCloseFd(fd: AsyncFD): Result[void, OSErrorCode] =
let loop = getThreadDispatcher()
if loop.contains(fd):
? unregister2(fd)
if closeFd(cint(fd)) != 0:
err(osLastError())
else:
ok()
proc close*(signal: ThreadSignalPtr): Result[void, string] =
## Close ThreadSignal object and free all the resources.
defer: deallocShared(signal)
when defined(windows):
# We do not need to perform unregistering on Windows, we can only close it.
if closeHandle(signal[].event) == 0'u32:
return err(osErrorMsg(osLastError()))
elif defined(linux):
let res = safeUnregisterAndCloseFd(signal[].efd)
if res.isErr():
return err(osErrorMsg(res.error))
else:
let res1 = safeUnregisterAndCloseFd(signal[].rfd)
let res2 = safeUnregisterAndCloseFd(signal[].wfd)
if res1.isErr(): return err(osErrorMsg(res1.error))
if res2.isErr(): return err(osErrorMsg(res2.error))
ok()
proc fireSync*(signal: ThreadSignalPtr,
timeout = InfiniteDuration): Result[bool, string] =
## Set state of ``signal`` to signaled state in blocking way.
##
## Returns ``false`` if signal was not signalled in time, and ``true``
## if operation was successful.
when defined(windows):
if setEvent(signal[].event) == 0'u32:
return err(osErrorMsg(osLastError()))
ok(true)
else:
let
eventFd =
when defined(linux):
cint(signal[].efd)
else:
cint(signal[].wfd)
checkFd =
when defined(linux):
cint(signal[].efd)
else:
cint(signal[].rfd)
if checkBusy(checkFd):
# Signal is already in signalled state
return ok(true)
var data = 1'u64
while true:
let res =
when defined(linux):
handleEintr(write(eventFd, addr data, sizeof(uint64)))
else:
handleEintr(send(SocketHandle(eventFd), addr data, sizeof(uint64),
MSG_NOSIGNAL))
if res < 0:
let errorCode = osLastError()
case errorCode
of EAGAIN:
let wres = waitReady(eventFd, WaitKind.Write, timeout)
if wres.isErr():
return err(osErrorMsg(wres.error))
if not(wres.get()):
return ok(false)
else:
return err(osErrorMsg(errorCode))
elif res != sizeof(data):
return err(osErrorMsg(EINVAL))
else:
return ok(true)
proc waitSync*(signal: ThreadSignalPtr,
timeout = InfiniteDuration): Result[bool, string] =
## Wait until the signal become signaled. This procedure is ``NOT`` async,
## so it blocks execution flow, but this procedure do not need asynchronous
## event loop to be present.
when defined(windows):
let
timeoutWin =
if timeout.isInfinite():
INFINITE
else:
DWORD(timeout.milliseconds())
handle = signal[].event
res = waitForSingleObject(handle, timeoutWin)
if res == WAIT_OBJECT_0:
ok(true)
elif res == WAIT_TIMEOUT:
ok(false)
elif res == WAIT_ABANDONED:
err("The wait operation has been abandoned")
else:
err("The wait operation has been failed")
else:
let eventFd =
when defined(linux):
cint(signal[].efd)
else:
cint(signal[].rfd)
var
data = 0'u64
timer = timeout
while true:
let wres =
block:
let
start = Moment.now()
res = waitReady(eventFd, WaitKind.Read, timer)
timer = timer - (Moment.now() - start)
res
if wres.isErr():
return err(osErrorMsg(wres.error))
if not(wres.get()):
return ok(false)
let res =
when defined(linux):
handleEintr(read(eventFd, addr data, sizeof(uint64)))
else:
handleEintr(recv(SocketHandle(eventFd), addr data, sizeof(uint64),
cint(0)))
if res < 0:
let errorCode = osLastError()
# If errorCode == EAGAIN it means that reading operation is already
# pending and so some other consumer reading eventfd or pipe end, in
# this case we going to ignore error and wait for another event.
if errorCode != EAGAIN:
return err(osErrorMsg(errorCode))
elif res != sizeof(data):
return err(osErrorMsg(EINVAL))
else:
return ok(true)
proc fire*(signal: ThreadSignalPtr): Future[void] =
## Set state of ``signal`` to signaled in asynchronous way.
var retFuture = newFuture[void]("asyncthreadsignal.fire")
when defined(windows):
if setEvent(signal[].event) == 0'u32:
retFuture.fail(newException(AsyncError, osErrorMsg(osLastError())))
else:
retFuture.complete()
else:
var data = 1'u64
let
eventFd =
when defined(linux):
cint(signal[].efd)
else:
cint(signal[].wfd)
checkFd =
when defined(linux):
cint(signal[].efd)
else:
cint(signal[].rfd)
proc continuation(udata: pointer) {.gcsafe, raises: [].} =
if not(retFuture.finished()):
let res =
when defined(linux):
handleEintr(write(eventFd, addr data, sizeof(uint64)))
else:
handleEintr(send(SocketHandle(eventFd), addr data, sizeof(uint64),
MSG_NOSIGNAL))
if res < 0:
let errorCode = osLastError()
discard removeWriter2(AsyncFD(eventFd))
retFuture.fail(newException(AsyncError, osErrorMsg(errorCode)))
elif res != sizeof(data):
discard removeWriter2(AsyncFD(eventFd))
retFuture.fail(newException(AsyncError, osErrorMsg(EINVAL)))
else:
let eres = removeWriter2(AsyncFD(eventFd))
if eres.isErr():
retFuture.fail(newException(AsyncError, osErrorMsg(eres.error)))
else:
retFuture.complete()
proc cancellation(udata: pointer) {.gcsafe, raises: [].} =
if not(retFuture.finished()):
discard removeWriter2(AsyncFD(eventFd))
if checkBusy(checkFd):
# Signal is already in signalled state
retFuture.complete()
return retFuture
let res =
when defined(linux):
handleEintr(write(eventFd, addr data, sizeof(uint64)))
else:
handleEintr(send(SocketHandle(eventFd), addr data, sizeof(uint64),
MSG_NOSIGNAL))
if res < 0:
let errorCode = osLastError()
case errorCode
of EAGAIN:
let loop = getThreadDispatcher()
if not(loop.contains(AsyncFD(eventFd))):
let rres = register2(AsyncFD(eventFd))
if rres.isErr():
retFuture.fail(newException(AsyncError, osErrorMsg(rres.error)))
return retFuture
let wres = addWriter2(AsyncFD(eventFd), continuation)
if wres.isErr():
retFuture.fail(newException(AsyncError, osErrorMsg(wres.error)))
else:
retFuture.cancelCallback = cancellation
else:
retFuture.fail(newException(AsyncError, osErrorMsg(errorCode)))
elif res != sizeof(data):
retFuture.fail(newException(AsyncError, osErrorMsg(EINVAL)))
else:
retFuture.complete()
retFuture
when defined(windows):
proc wait*(signal: ThreadSignalPtr) {.async.} =
let handle = signal[].event
let res = await waitForSingleObject(handle, InfiniteDuration)
# There should be no other response, because we use `InfiniteDuration`.
doAssert(res == WaitableResult.Ok)
else:
proc wait*(signal: ThreadSignalPtr): Future[void] =
var retFuture = newFuture[void]("asyncthreadsignal.wait")
var data = 1'u64
let eventFd =
when defined(linux):
cint(signal[].efd)
else:
cint(signal[].rfd)
proc continuation(udata: pointer) {.gcsafe, raises: [].} =
if not(retFuture.finished()):
let res =
when defined(linux):
handleEintr(read(eventFd, addr data, sizeof(uint64)))
else:
handleEintr(recv(SocketHandle(eventFd), addr data, sizeof(uint64),
cint(0)))
if res < 0:
let errorCode = osLastError()
# If errorCode == EAGAIN it means that reading operation is already
# pending and so some other consumer reading eventfd or pipe end, in
# this case we going to ignore error and wait for another event.
if errorCode != EAGAIN:
discard removeReader2(AsyncFD(eventFd))
retFuture.fail(newException(AsyncError, osErrorMsg(errorCode)))
elif res != sizeof(data):
discard removeReader2(AsyncFD(eventFd))
retFuture.fail(newException(AsyncError, osErrorMsg(EINVAL)))
else:
let eres = removeReader2(AsyncFD(eventFd))
if eres.isErr():
retFuture.fail(newException(AsyncError, osErrorMsg(eres.error)))
else:
retFuture.complete()
proc cancellation(udata: pointer) {.gcsafe, raises: [].} =
if not(retFuture.finished()):
# Future is already cancelled so we ignore errors.
discard removeReader2(AsyncFD(eventFd))
let loop = getThreadDispatcher()
if not(loop.contains(AsyncFD(eventFd))):
let res = register2(AsyncFD(eventFd))
if res.isErr():
retFuture.fail(newException(AsyncError, osErrorMsg(res.error)))
return retFuture
let res = addReader2(AsyncFD(eventFd), continuation)
if res.isErr():
retFuture.fail(newException(AsyncError, osErrorMsg(res.error)))
return retFuture
retFuture.cancelCallback = cancellation
retFuture