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core.atomic
The atomic module provides basic support for lock-free
concurrent programming.
License:
Authors:
Sean Kelly, Alex Rønne Petersen, Manu Evans
Source core/atomic.d
- enum
MemoryOrder
: int; - Specifies the memory ordering semantics of an atomic operation.
raw
- Not sequenced. Corresponds to LLVM AtomicOrdering.Monotonic and C++11/C11 memory_order_relaxed.
acq
- Hoist-load + hoist-store barrier. Corresponds to LLVM AtomicOrdering.Acquire and C++11/C11 memory_order_acquire.
rel
- Sink-load + sink-store barrier. Corresponds to LLVM AtomicOrdering.Release and C++11/C11 memory_order_release.
acq_rel
- Acquire + release barrier. Corresponds to LLVM AtomicOrdering.AcquireRelease and C++11/C11 memory_order_acq_rel.
seq
- Fully sequenced (acquire + release). Corresponds to LLVM AtomicOrdering.SequentiallyConsistent and C++11/C11 memory_order_seq_cst.
- pure nothrow @nogc @trusted T
atomicLoad
(MemoryOrder ms = MemoryOrder.seq, T)(ref const Tval
)
if (!is(T == shared(U), U) && !is(T == shared(inout(U)), U) && !is(T == shared(const(U)), U));
pure nothrow @nogc @trusted TatomicLoad
(MemoryOrder ms = MemoryOrder.seq, T)(ref const shared Tval
)
if (!hasUnsharedIndirections!T);
pure nothrow @nogc @trusted TailShared!TatomicLoad
(MemoryOrder ms = MemoryOrder.seq, T)(ref const shared Tval
)
if (hasUnsharedIndirections!T); - Loads 'val' from memory and returns it. The memory barrier specified by 'ms' is applied to the operation, which is fully sequenced by default. Valid memory orders are MemoryOrder.raw, MemoryOrder.acq, and MemoryOrder.seq.Parameters:
T val
The target variable. Returns:The value of 'val'. - pure nothrow @nogc @trusted void
atomicStore
(MemoryOrder ms = MemoryOrder.seq, T, V)(ref Tval
, Vnewval
)
if (!is(T == shared) && !is(V == shared));
pure nothrow @nogc @trusted voidatomicStore
(MemoryOrder ms = MemoryOrder.seq, T, V)(ref shared Tval
, Vnewval
)
if (!is(T == class));
pure nothrow @nogc @trusted voidatomicStore
(MemoryOrder ms = MemoryOrder.seq, T, V)(ref shared Tval
, shared Vnewval
)
if (is(T == class)); - Writes 'newval' into 'val'. The memory barrier specified by 'ms' is applied to the operation, which is fully sequenced by default. Valid memory orders are MemoryOrder.raw, MemoryOrder.rel, and MemoryOrder.seq.Parameters:
T val
The target variable. V newval
The value to store. - pure nothrow @nogc @trusted T
atomicFetchAdd
(MemoryOrder ms = MemoryOrder.seq, T)(ref Tval
, size_tmod
)
if ((__traits(isIntegral, T) || is(T == U*, U)) && !is(T == shared));
pure nothrow @nogc @trusted TatomicFetchAdd
(MemoryOrder ms = MemoryOrder.seq, T)(ref shared Tval
, size_tmod
)
if (__traits(isIntegral, T) || is(T == U*, U)); - Atomically adds
mod
to the value referenced byval
and returns the valueval
held previously. This operation is both lock-free and atomic.Parameters:T val
Reference to the value to modify. size_t mod
The value to add. Returns:The value held previously byval
. - pure nothrow @nogc @trusted T
atomicFetchSub
(MemoryOrder ms = MemoryOrder.seq, T)(ref Tval
, size_tmod
)
if ((__traits(isIntegral, T) || is(T == U*, U)) && !is(T == shared));
pure nothrow @nogc @trusted TatomicFetchSub
(MemoryOrder ms = MemoryOrder.seq, T)(ref shared Tval
, size_tmod
)
if (__traits(isIntegral, T) || is(T == U*, U)); - Atomically subtracts
mod
from the value referenced byval
and returns the valueval
held previously. This operation is both lock-free and atomic.Parameters:T val
Reference to the value to modify. size_t mod
The value to subtract. Returns:The value held previously byval
. - pure nothrow @nogc @trusted T
atomicExchange
(MemoryOrder ms = MemoryOrder.seq, T, V)(T*here
, VexchangeWith
)
if (!is(T == shared) && !is(V == shared));
pure nothrow @nogc @trusted TailShared!TatomicExchange
(MemoryOrder ms = MemoryOrder.seq, T, V)(shared(T)*here
, VexchangeWith
)
if (!is(T == class) && !is(T == interface));
pure nothrow @nogc @trusted shared(T)atomicExchange
(MemoryOrder ms = MemoryOrder.seq, T, V)(shared(T)*here
, shared(V)exchangeWith
)
if (is(T == class) || is(T == interface)); - Exchange
exchangeWith
with the memory referenced byhere
. This operation is both lock-free and atomic.Parameters:T* here
The address of the destination variable. V exchangeWith
The value to exchange. Returns:The value held previously byhere
. - template
cas
(MemoryOrder succ = MemoryOrder.seq, MemoryOrder fail = MemoryOrder.seq) - Performs either compare-and-set or compare-and-swap (or exchange).There are two categories of overloads in this template: The first category does a simple compare-and-set. The comparison value (ifThis) is treated as an rvalue. The second category does a compare-and-swap (a.k.a. compare-and-exchange), and expects ifThis to be a pointer type, where the previous value of here will be written. This operation is both lock-free and atomic.Parameters:
T* here The address of the destination variable. V2 writeThis The value to store. V1 ifThis The comparison value. Returns:true if the store occurred, false if not.- pure nothrow @nogc @trusted bool
cas
(T, V1, V2)(T*here
, V1ifThis
, V2writeThis
)
if (!is(T == shared) && is(T : V1)); - Compare-and-set for non-shared values
- pure nothrow @nogc @trusted bool
cas
(T, V1, V2)(shared(T)*here
, V1ifThis
, V2writeThis
)
if (!is(T == class) && (is(T : V1) || is(shared(T) : V1))); - Compare-and-set for shared value type
- pure nothrow @nogc @trusted bool
cas
(T, V1, V2)(shared(T)*here
, shared(V1)ifThis
, shared(V2)writeThis
)
if (is(T == class)); - Compare-and-set for shared reference type (class)
- pure nothrow @nogc @trusted bool
cas
(T, V)(T*here
, T*ifThis
, VwriteThis
)
if (!is(T == shared) && !is(V == shared)); - Compare-and-exchange for non-shared types
- pure nothrow @nogc @trusted bool
cas
(T, V1, V2)(shared(T)*here
, V1*ifThis
, V2writeThis
)
if (!is(T == class) && (is(T : V1) || is(shared(T) : V1))); - Compare and exchange for mixed-sharedness types
- pure nothrow @nogc @trusted bool
cas
(T, V)(shared(T)*here
, shared(T)*ifThis
, shared(V)writeThis
)
if (is(T == class)); - Compare-and-exchange for class
- pure nothrow @nogc @trusted bool
casWeak
(MemoryOrder succ = MemoryOrder.seq, MemoryOrder fail = MemoryOrder.seq, T, V1, V2)(T*here
, V1ifThis
, V2writeThis
)
if (!is(T == shared) && is(T : V1));
pure nothrow @nogc @trusted boolcasWeak
(MemoryOrder succ = MemoryOrder.seq, MemoryOrder fail = MemoryOrder.seq, T, V1, V2)(shared(T)*here
, V1ifThis
, V2writeThis
)
if (!is(T == class) && (is(T : V1) || is(shared(T) : V1)));
pure nothrow @nogc @trusted boolcasWeak
(MemoryOrder succ = MemoryOrder.seq, MemoryOrder fail = MemoryOrder.seq, T, V1, V2)(shared(T)*here
, shared(V1)ifThis
, shared(V2)writeThis
)
if (is(T == class)); - Stores 'writeThis' to the memory referenced by 'here' if the value referenced by 'here' is equal to 'ifThis'. The 'weak' version of cas may spuriously fail. It is recommended to use
casWeak
only when cas would be used in a loop. This operation is both lock-free and atomic.Parameters:T* here
The address of the destination variable. V2 writeThis
The value to store. V1 ifThis
The comparison value. Returns:true if the store occurred, false if not. - pure nothrow @nogc @trusted bool
casWeak
(MemoryOrder succ = MemoryOrder.seq, MemoryOrder fail = MemoryOrder.seq, T, V)(T*here
, T*ifThis
, VwriteThis
)
if (!is(T == shared(S), S) && !is(V == shared(U), U));
pure nothrow @nogc @trusted boolcasWeak
(MemoryOrder succ = MemoryOrder.seq, MemoryOrder fail = MemoryOrder.seq, T, V1, V2)(shared(T)*here
, V1*ifThis
, V2writeThis
)
if (!is(T == class) && (is(T : V1) || is(shared(T) : V1)));
pure nothrow @nogc @trusted boolcasWeak
(MemoryOrder succ = MemoryOrder.seq, MemoryOrder fail = MemoryOrder.seq, T, V)(shared(T)*here
, shared(T)*ifThis
, shared(V)writeThis
)
if (is(T == class)); - Stores 'writeThis' to the memory referenced by 'here' if the value referenced by 'here' is equal to the value referenced by 'ifThis'. The prior value referenced by 'here' is written to
ifThis
and returned to the user. The 'weak' version of cas may spuriously fail. It is recommended to usecasWeak
only when cas would be used in a loop. This operation is both lock-free and atomic.Parameters:T* here
The address of the destination variable. V writeThis
The value to store. T* ifThis
The address of the value to compare, and receives the prior value of here
as output.Returns:true if the store occurred, false if not. - pure nothrow @nogc @safe void
atomicFence
(MemoryOrder order = MemoryOrder.seq)(); - Inserts a full load/store memory fence (on platforms that need it). This ensures that all loads and stores before a call to this function are executed before any loads and stores after the call.
- pure nothrow @nogc @safe void
pause
(); - Gives a hint to the processor that the calling thread is in a 'spin-wait' loop, allowing to more efficiently allocate resources.
- pure nothrow @nogc @safe TailShared!T
atomicOp
(string op, T, V1)(ref shared Tval
, V1mod
)
if (__traits(compiles, mixin("*cast(T*)&val
" ~ op ~ "mod
"))); - Performs the binary operation 'op' on val using 'mod' as the modifier.Parameters:
T val
The target variable. V1 mod
The modifier to apply. Returns:The result of the operation.
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