116 lines
4.0 KiB
Nim
116 lines
4.0 KiB
Nim
# SPDX-FileCopyrightText: ☭ Emery Hemingway
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# SPDX-License-Identifier: Unlicense
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import std/[sets, times]
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import pkg/sys/[handles, ioqueue]
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import preserves
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import ../../syndicate, ../bags, ../protocols/[timer, dataspace]
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export timer
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type
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Observe = dataspace.Observe
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when defined(linux):
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import std/[oserrors, posix]
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type Time = posix.Time
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{.pragma: timerfd, importc, header: "<sys/timerfd.h>".}
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proc timerfd_create(clock_id: ClockId, flags: cint): cint {.timerfd.}
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proc timerfd_settime(ufd: cint, flags: cint,
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utmr: var Itimerspec, otmr: var Itimerspec): cint {.timerfd.}
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proc timerfd_gettime(ufd: cint, curr: var Itimerspec): cint {.timerfd.}
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var
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TFD_NONBLOCK {.timerfd.}: cint
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TFD_CLOEXEC {.timerfd.}: cint
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TFD_TIMER_ABSTIME {.timerfd.}: cint
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proc `<`(a, b: Timespec): bool =
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a.tv_sec.clong < b.tv_sec.clong or
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(a.tv_sec.clong == b.tv_sec.clong and a.tv_nsec < b.tv_nsec)
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proc `+`(a, b: Timespec): Timespec =
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result.tv_sec = Time a.tv_sec.clong + b.tv_sec.clong
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result.tv_nsec = a.tv_nsec + b.tv_nsec
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func toFloat(ts: Timespec): float =
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ts.tv_sec.float + ts.tv_nsec.float / 1_000_000_000
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func toTimespec(f: float): Timespec =
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result.tv_sec = Time(f)
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result.tv_nsec = clong(uint64(f * 1_000_000_000) mod 1_000_000_000)
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proc clock_realtime: Timespec =
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if clock_gettime(CLOCK_REALTIME, result) < 0:
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raiseOSError(osLastError(), "clock_gettime")
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type
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TimerDriver = ref object
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facet: Facet
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## Owning facet of driver.
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target: Cap
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## Destination for LaterThan assertions.
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deadlines: Bag[float]
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## Deadlines that other actors are observing.
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timers: HashSet[cint]
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# TODO: use a single timer descriptor
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proc spawnTimerDriver(facet: Facet; cap: Cap): TimerDriver =
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let driver = TimerDriver(facet: facet, target: cap)
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facet.onStop do (turn: var Turn):
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for fd in driver.timers:
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unregister(FD fd)
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discard close(fd)
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driver
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proc earliestFloat(driver: TimerDriver): float =
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assert driver.deadlines.len > 0
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result = high float
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for deadline in driver.deadlines:
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if deadline < result:
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result = deadline
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proc await(driver: TimerDriver; deadline: float) {.asyncio.} =
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## Run timer driver concurrently with actor.
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let fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK or TFD_CLOEXEC)
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if fd < 0:
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raiseOSError(osLastError(), "failed to acquire timer descriptor")
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var
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old: Itimerspec
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its = Itimerspec(it_value: deadline.toTimespec)
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if timerfd_settime(fd, TFD_TIMER_ABSTIME, its, old) < 0:
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raiseOSError(osLastError(), "failed to set timeout")
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driver.timers.incl(fd)
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while clock_realtime() < its.it_value:
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# Check if the timer is expired which
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# could happen before waiting.
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wait(FD fd, Read)
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if deadline in driver.deadlines:
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# Check if the deadline is still observed.
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proc turnWork(turn: var Turn) =
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discard publish(turn, driver.target, LaterThan(seconds: deadline))
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run(driver.facet, turnWork)
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discard close(fd)
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driver.timers.excl(fd)
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proc spawnTimerActor*(ds: Cap; turn: var Turn): Actor {.discardable.} =
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## Spawn a timer actor that responds to
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## dataspace observations of timeouts on `ds`.
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spawnActor("timers", turn) do (turn: var Turn):
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let driver = spawnTimerDriver(turn.facet, ds)
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let pat = inject(grab Observe(pattern: dropType LaterThan), {0: grabLit()})
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during(turn, ds, pat) do (deadline: float):
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if change(driver.deadlines, deadline, +1) == cdAbsentToPresent:
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discard trampoline(whelp await(driver, deadline))
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do:
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discard change(driver.deadlines, deadline, -1, clamp = true)
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# TODO: retract assertions that are unobserved.
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proc after*(turn: var Turn; ds: Cap; dur: Duration; act: TurnAction) =
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## Execute `act` after some duration of time.
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var later = clock_realtime().toFloat() + dur.inMilliseconds.float / 1_000.0
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onPublish(turn, ds, grab LaterThan(seconds: later)):
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act(turn)
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