unconditionally pass through std/atomics and deprecate shim/atomics (#196)

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when (NimMajor,NimMinor,NimPatch) >= (0,20,0):
import std/concurrency/atomics
export atomics
else:
# Backport of Nim 0.20 atomics to earlier versions
#
#
# Nim's Runtime Library
# (c) Copyright 2018 Jörg Wollenschläger
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## Types and operations for atomic operations and lockless algorithms.
when defined(cpp) or defined(nimdoc):
# For the C++ backend, types and operations map directly to C++11 atomics.
{.push, header: "<atomic>".}
type
MemoryOrder* {.importcpp: "std::memory_order".} = enum
## Specifies how non-atomic operations can be reordered around atomic
## operations.
moRelaxed
## No ordering constraints. Only the atomicity and ordering against
## other atomic operations is guaranteed.
moConsume
## This ordering is currently discouraged as it's semantics are
## being revised. Acquire operations should be preferred.
moAcquire
## When applied to a load operation, no reads or writes in the
## current thread can be reordered before this operation.
moRelease
## When applied to a store operation, no reads or writes in the
## current thread can be reorderd after this operation.
moAcquireRelease
## When applied to a read-modify-write operation, this behaves like
## both an acquire and a release operation.
moSequentiallyConsistent
## Behaves like Acquire when applied to load, like Release when
## applied to a store and like AcquireRelease when applied to a
## read-modify-write operation.
## Also garantees that all threads observe the same total ordering
## with other moSequentiallyConsistent operations.
type
Atomic* {.importcpp: "std::atomic".} [T] = object
## An atomic object with underlying type `T`.
AtomicFlag* {.importcpp: "std::atomic_flag".} = object
## An atomic boolean state.
# Access operations
proc load*[T](location: var Atomic[T]; order: MemoryOrder = moSequentiallyConsistent): T {.importcpp: "#.load(@)".}
## Atomically obtains the value of the atomic object.
proc store*[T](location: var Atomic[T]; desired: T; order: MemoryOrder = moSequentiallyConsistent) {.importcpp: "#.store(@)".}
## Atomically replaces the value of the atomic object with the `desired`
## value.
proc exchange*[T](location: var Atomic[T]; desired: T; order: MemoryOrder = moSequentiallyConsistent): T {.importcpp: "#.exchange(@)".}
## Atomically replaces the value of the atomic object with the `desired`
## value and returns the old value.
proc compareExchange*[T](location: var Atomic[T]; expected: var T; desired: T; order: MemoryOrder = moSequentiallyConsistent): bool {.importcpp: "#.compare_exchange_strong(@)".}
## Atomically compares the value of the atomic object with the `expected`
## value and performs exchange with the `desired` one if equal or load if
## not. Returns true if the exchange was successful.
proc compareExchange*[T](location: var Atomic[T]; expected: var T; desired: T; success, failure: MemoryOrder): bool {.importcpp: "#.compare_exchange_strong(@)".}
## Same as above, but allows for different memory orders for success and
## failure.
proc compareExchangeWeak*[T](location: var Atomic[T]; expected: var T; desired: T; order: MemoryOrder = moSequentiallyConsistent): bool {.importcpp: "#.compare_exchange_weak(@)".}
## Same as above, but is allowed to fail spuriously.
proc compareExchangeWeak*[T](location: var Atomic[T]; expected: var T; desired: T; success, failure: MemoryOrder): bool {.importcpp: "#.compare_exchange_weak(@)".}
## Same as above, but allows for different memory orders for success and
## failure.
# Numerical operations
proc fetchAdd*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importcpp: "#.fetch_add(@)".}
## Atomically adds a `value` to the atomic integer and returns the
## original value.
proc fetchSub*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importcpp: "#.fetch_sub(@)".}
## Atomically subtracts a `value` to the atomic integer and returns the
## original value.
proc fetchAnd*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importcpp: "#.fetch_and(@)".}
## Atomically replaces the atomic integer with it's bitwise AND
## with the specified `value` and returns the original value.
proc fetchOr*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importcpp: "#.fetch_or(@)".}
## Atomically replaces the atomic integer with it's bitwise OR
## with the specified `value` and returns the original value.
proc fetchXor*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importcpp: "#.fetch_xor(@)".}
## Atomically replaces the atomic integer with it's bitwise XOR
## with the specified `value` and returns the original value.
# Flag operations
proc testAndSet*(location: var AtomicFlag; order: MemoryOrder = moSequentiallyConsistent): bool {.importcpp: "#.test_and_set(@)".}
## Atomically sets the atomic flag to true and returns the original value.
proc clear*(location: var AtomicFlag; order: MemoryOrder = moSequentiallyConsistent) {.importcpp: "#.clear(@)".}
## Atomically sets the value of the atomic flag to false.
proc fence*(order: MemoryOrder) {.importcpp: "std::atomic_thread_fence(@)".}
## Ensures memory ordering without using atomic operations.
proc signalFence*(order: MemoryOrder) {.importcpp: "std::atomic_signal_fence(@)".}
## Prevents reordering of accesses by the compiler as would fence, but
## inserts no CPU instructions for memory ordering.
{.pop.}
else:
# For the C backend, atomics map to C11 built-ins on GCC and Clang for
# trivial Nim types. Other types are implemented using spin locks.
# This could be overcome by supporting advanced importc-patterns.
# Since MSVC does not implement C11, we fall back to MS intrinsics
# where available.
type
Trivial = SomeNumber | bool | ptr | pointer
# A type that is known to be atomic and whose size is known at
# compile time to be 8 bytes or less
template nonAtomicType*(T: typedesc[Trivial]): untyped =
# Maps types to integers of the same size
when sizeof(T) == 1: int8
elif sizeof(T) == 2: int16
elif sizeof(T) == 4: int32
elif sizeof(T) == 8: int64
when defined(vcc):
# TODO: Trivial types should be volatile and use VC's special volatile
# semantics for store and loads.
type
MemoryOrder* = enum
moRelaxed
moConsume
moAcquire
moRelease
moAcquireRelease
moSequentiallyConsistent
Atomic*[T] = object
when T is Trivial:
value: T.nonAtomicType
else:
nonAtomicValue: T
guard: AtomicFlag
AtomicFlag* = distinct int8
{.push header: "<intrin.h>".}
# MSVC intrinsics
proc interlockedExchange(location: pointer; desired: int8): int8 {.importc: "_InterlockedExchange8".}
proc interlockedExchange(location: pointer; desired: int16): int16 {.importc: "_InterlockedExchange".}
proc interlockedExchange(location: pointer; desired: int32): int32 {.importc: "_InterlockedExchange16".}
proc interlockedExchange(location: pointer; desired: int64): int64 {.importc: "_InterlockedExchange64".}
proc interlockedCompareExchange(location: pointer; desired, expected: int8): int8 {.importc: "_InterlockedCompareExchange8".}
proc interlockedCompareExchange(location: pointer; desired, expected: int16): int16 {.importc: "_InterlockedCompareExchange16".}
proc interlockedCompareExchange(location: pointer; desired, expected: int32): int32 {.importc: "_InterlockedCompareExchange".}
proc interlockedCompareExchange(location: pointer; desired, expected: int64): int64 {.importc: "_InterlockedCompareExchange64".}
proc interlockedAnd(location: pointer; value: int8): int8 {.importc: "_InterlockedAnd8".}
proc interlockedAnd(location: pointer; value: int16): int16 {.importc: "_InterlockedAnd16".}
proc interlockedAnd(location: pointer; value: int32): int32 {.importc: "_InterlockedAnd".}
proc interlockedAnd(location: pointer; value: int64): int64 {.importc: "_InterlockedAnd64".}
proc interlockedOr(location: pointer; value: int8): int8 {.importc: "_InterlockedOr8".}
proc interlockedOr(location: pointer; value: int16): int16 {.importc: "_InterlockedOr16".}
proc interlockedOr(location: pointer; value: int32): int32 {.importc: "_InterlockedOr".}
proc interlockedOr(location: pointer; value: int64): int64 {.importc: "_InterlockedOr64".}
proc interlockedXor(location: pointer; value: int8): int8 {.importc: "_InterlockedXor8".}
proc interlockedXor(location: pointer; value: int16): int16 {.importc: "_InterlockedXor16".}
proc interlockedXor(location: pointer; value: int32): int32 {.importc: "_InterlockedXor".}
proc interlockedXor(location: pointer; value: int64): int64 {.importc: "_InterlockedXor64".}
proc fence(order: MemoryOrder): int64 {.importc: "_ReadWriteBarrier()".}
proc signalFence(order: MemoryOrder): int64 {.importc: "_ReadWriteBarrier()".}
{.pop.}
proc testAndSet*(location: var AtomicFlag; order: MemoryOrder = moSequentiallyConsistent): bool =
interlockedOr(addr(location), 1'i8) == 1'i8
proc clear*(location: var AtomicFlag; order: MemoryOrder = moSequentiallyConsistent) =
discard interlockedAnd(addr(location), 0'i8)
proc load*[T: Trivial](location: var Atomic[T]; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](interlockedOr(addr(location.value), (nonAtomicType(T))0))
proc store*[T: Trivial](location: var Atomic[T]; desired: T; order: MemoryOrder = moSequentiallyConsistent) {.inline.} =
discard interlockedExchange(addr(location.value), cast[nonAtomicType(T)](desired))
proc exchange*[T: Trivial](location: var Atomic[T]; desired: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](interlockedExchange(addr(location.value), cast[int64](desired)))
proc compareExchange*[T: Trivial](location: var Atomic[T]; expected: var T; desired: T; success, failure: MemoryOrder): bool {.inline.} =
cast[T](interlockedCompareExchange(addr(location.value), cast[nonAtomicType(T)](desired), cast[nonAtomicType(T)](expected))) == expected
proc compareExchange*[T: Trivial](location: var Atomic[T]; expected: var T; desired: T; order: MemoryOrder = moSequentiallyConsistent): bool {.inline.} =
compareExchange(location, expected, desired, order, order)
proc compareExchangeWeak*[T: Trivial](location: var Atomic[T]; expected: var T; desired: T; success, failure: MemoryOrder): bool {.inline.} =
compareExchange(location, expected, desired, success, failure)
proc compareExchangeWeak*[T: Trivial](location: var Atomic[T]; expected: var T; desired: T; order: MemoryOrder = moSequentiallyConsistent): bool {.inline.} =
compareExchangeWeak(location, expected, desired, order, order)
proc fetchAdd*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
var currentValue = location.load()
while not compareExchangeWeak(location, currentValue, currentValue + value): discard
proc fetchSub*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
fetchAdd(location, -value, order)
proc fetchAnd*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](interlockedAnd(addr(location.value), cast[nonAtomicType(T)](value)))
proc fetchOr*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](interlockedOr(addr(location.value), cast[nonAtomicType(T)](value)))
proc fetchXor*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](interlockedXor(addr(location.value), cast[nonAtomicType(T)](value)))
else:
{.push, header: "<stdatomic.h>".}
type
MemoryOrder* {.importc: "memory_order".} = enum
moRelaxed
moConsume
moAcquire
moRelease
moAcquireRelease
moSequentiallyConsistent
type
# Atomic* {.importcpp: "_Atomic('0)".} [T] = object
AtomicInt8 {.importc: "_Atomic NI8".} = object
AtomicInt16 {.importc: "_Atomic NI16".} = object
AtomicInt32 {.importc: "_Atomic NI32".} = object
AtomicInt64 {.importc: "_Atomic NI64".} = object
template atomicType*(T: typedesc[Trivial]): untyped =
# Maps the size of a trivial type to it's internal atomic type
when sizeof(T) == 1: AtomicInt8
elif sizeof(T) == 2: AtomicInt16
elif sizeof(T) == 4: AtomicInt32
elif sizeof(T) == 8: AtomicInt64
type
AtomicFlag* {.importc: "atomic_flag".} = object
Atomic*[T] = object
when T is Trivial:
value: T.atomicType
else:
nonAtomicValue: T
guard: AtomicFlag
#proc init*[T](location: var Atomic[T]; value: T): T {.importcpp: "atomic_init(@)".}
proc atomic_load_explicit[T, A](location: ptr A; order: MemoryOrder): T {.importc.}
proc atomic_store_explicit[T, A](location: ptr A; desired: T; order: MemoryOrder = moSequentiallyConsistent) {.importc.}
proc atomic_exchange_explicit[T, A](location: ptr A; desired: T; order: MemoryOrder = moSequentiallyConsistent): T {.importc.}
proc atomic_compare_exchange_strong_explicit[T, A](location: ptr A; expected: ptr T; desired: T; success, failure: MemoryOrder): bool {.importc.}
proc atomic_compare_exchange_weak_explicit[T, A](location: ptr A; expected: ptr T; desired: T; success, failure: MemoryOrder): bool {.importc.}
# Numerical operations
proc atomic_fetch_add_explicit[T, A](location: ptr A; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importc.}
proc atomic_fetch_sub_explicit[T, A](location: ptr A; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importc.}
proc atomic_fetch_and_explicit[T, A](location: ptr A; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importc.}
proc atomic_fetch_or_explicit[T, A](location: ptr A; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importc.}
proc atomic_fetch_xor_explicit[T, A](location: ptr A; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.importc.}
# Flag operations
# var ATOMIC_FLAG_INIT {.importc, nodecl.}: AtomicFlag
# proc init*(location: var AtomicFlag) {.inline.} = location = ATOMIC_FLAG_INIT
proc testAndSet*(location: var AtomicFlag; order: MemoryOrder = moSequentiallyConsistent): bool {.importc: "atomic_flag_test_and_set_explicit".}
proc clear*(location: var AtomicFlag; order: MemoryOrder = moSequentiallyConsistent) {.importc: "atomic_flag_clear_explicit".}
proc fence*(order: MemoryOrder) {.importc: "atomic_thread_fence".}
proc signalFence*(order: MemoryOrder) {.importc: "atomic_signal_fence".}
{.pop.}
proc load*[T: Trivial](location: var Atomic[T]; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](atomic_load_explicit[nonAtomicType(T), type(location.value)](addr(location.value), order))
proc store*[T: Trivial](location: var Atomic[T]; desired: T; order: MemoryOrder = moSequentiallyConsistent) {.inline.} =
atomic_store_explicit(addr(location.value), cast[nonAtomicType(T)](desired), order)
proc exchange*[T: Trivial](location: var Atomic[T]; desired: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](atomic_exchange_explicit(addr(location.value), cast[nonAtomicType(T)](desired), order))
proc compareExchange*[T: Trivial](location: var Atomic[T]; expected: var T; desired: T; success, failure: MemoryOrder): bool {.inline.} =
atomic_compare_exchange_strong_explicit(addr(location.value), cast[ptr nonAtomicType(T)](addr(expected)), cast[nonAtomicType(T)](desired), success, failure)
proc compareExchange*[T: Trivial](location: var Atomic[T]; expected: var T; desired: T; order: MemoryOrder = moSequentiallyConsistent): bool {.inline.} =
compareExchange(location, expected, desired, order, order)
proc compareExchangeWeak*[T: Trivial](location: var Atomic[T]; expected: var T; desired: T; success, failure: MemoryOrder): bool {.inline.} =
atomic_compare_exchange_weak_explicit(addr(location.value), cast[ptr nonAtomicType(T)](addr(expected)), cast[nonAtomicType(T)](desired), success, failure)
proc compareExchangeWeak*[T: Trivial](location: var Atomic[T]; expected: var T; desired: T; order: MemoryOrder = moSequentiallyConsistent): bool {.inline.} =
compareExchangeWeak(location, expected, desired, order, order)
# Numerical operations
proc fetchAdd*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](atomic_fetch_add_explicit(addr(location.value), cast[nonAtomicType(T)](value), order))
proc fetchSub*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](atomic_fetch_sub_explicit(addr(location.value), cast[nonAtomicType(T)](value), order))
proc fetchAnd*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](atomic_fetch_and_explicit(addr(location.value), cast[nonAtomicType(T)](value), order))
proc fetchOr*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](atomic_fetch_or_explicit(addr(location.value), cast[nonAtomicType(T)](value), order))
proc fetchXor*[T: SomeInteger](location: var Atomic[T]; value: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
cast[T](atomic_fetch_xor_explicit(addr(location.value), cast[nonAtomicType(T)](value), order))
template withLock[T: not Trivial](location: var Atomic[T]; order: MemoryOrder; body: untyped): untyped =
while location.guard.testAndSet(moAcquire): discard
body
location.guard.clear(moRelease)
proc load*[T: not Trivial](location: var Atomic[T]; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
withLock(location, order):
result = location.nonAtomicValue
proc store*[T: not Trivial](location: var Atomic[T]; desired: T; order: MemoryOrder = moSequentiallyConsistent) {.inline.} =
withLock(location, order):
location.nonAtomicValue = desired
proc exchange*[T: not Trivial](location: var Atomic[T]; desired: T; order: MemoryOrder = moSequentiallyConsistent): T {.inline.} =
withLock(location, order):
result = location.nonAtomicValue
location.nonAtomicValue = desired
proc compareExchange*[T: not Trivial](location: var Atomic[T]; expected: var T; desired: T; success, failure: MemoryOrder): bool {.inline.} =
withLock(location, success):
if location.nonAtomicValue != expected:
return false
swap(location.nonAtomicValue, expected)
return true
proc compareExchangeWeak*[T: not Trivial](location: var Atomic[T]; expected: var T; desired: T; success, failure: MemoryOrder): bool {.inline.} =
withLock(location, success):
if location.nonAtomicValue != expected:
return false
swap(location.nonAtomicValue, expected)
return true
proc compareExchange*[T: not Trivial](location: var Atomic[T]; expected: var T; desired: T; order: MemoryOrder = moSequentiallyConsistent): bool {.inline.} =
compareExchange(location, expected, desired, order, order)
proc compareExchangeWeak*[T: not Trivial](location: var Atomic[T]; expected: var T; desired: T; order: MemoryOrder = moSequentiallyConsistent): bool {.inline.} =
compareExchangeWeak(location, expected, desired, order, order)
proc atomicInc*[T: SomeInteger](location: var Atomic[T]; value: T = 1) {.inline.} =
## Atomically increments the atomic integer by some `value`.
discard location.fetchAdd(value)
proc atomicDec*[T: SomeInteger](location: var Atomic[T]; value: T = 1) {.inline.} =
## Atomically decrements the atomic integer by some `value`.
discard location.fetchSub(value)
proc `+=`*[T: SomeInteger](location: var Atomic[T]; value: T) {.inline.} =
## Atomically increments the atomic integer by some `value`.
discard location.fetchAdd(value)
proc `-=`*[T: SomeInteger](location: var Atomic[T]; value: T) {.inline.} =
## Atomically decrements the atomic integer by some `value`.
discard location.fetchSub(value)
{.deprecated: "use std/atomics".}
import std/concurrency/atomics
export atomics