core.atomic

The atomic module provides basic support for lock-free concurrent programming.

Use the -preview=nosharedaccess compiler flag to detect unsafe individual read or write operations on shared data.

Members

Enums

MemoryOrder enum MemoryOrder: Specifies the memory ordering semantics of an atomic operation.

Functions

atomicExchange T atomicExchange(T* here, V exchangeWith)
TailShared!T atomicExchange(shared(T)* here, V exchangeWith)
shared(T) atomicExchange(shared(T)* here, shared(V) exchangeWith): Exchange exchangeWith with the memory referenced by here. This operation is both lock-free and atomic.
atomicFence void atomicFence(): 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.
atomicFetchAdd T atomicFetchAdd(T val, size_t mod): Atomically adds mod to the value referenced by val and returns the value val held previously. This operation is both lock-free and atomic.
atomicFetchSub T atomicFetchSub(T val, size_t mod): Atomically subtracts mod from the value referenced by val and returns the value val held previously. This operation is both lock-free and atomic.
atomicLoad T atomicLoad(T val)
TailShared!T atomicLoad(T val): 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.
atomicOp TailShared!T atomicOp(T val, V1 mod): Performs the binary operation 'op' on val using 'mod' as the modifier.
atomicStore void atomicStore(T val, V newval): 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.
casWeak bool casWeak(T* here, V1 ifThis, V2 writeThis)
bool casWeak(shared(T)* here, V1 ifThis, V2 writeThis)
bool casWeak(shared(T)* here, shared(V1) ifThis, shared(V2) writeThis): 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.
casWeak bool casWeak(T* here, T* ifThis, V writeThis)
bool casWeak(shared(T)* here, V1* ifThis, V2 writeThis)
bool casWeak(shared(T)* here, shared(T)* ifThis, shared(V) writeThis): 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 use casWeak only when cas would be used in a loop. This operation is both lock-free and atomic.
pause void pause(): Gives a hint to the processor that the calling thread is in a 'spin-wait' loop, allowing to more efficiently allocate resources.
testCAS void testCAS(T val): ///////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////
testLoadStore void testLoadStore(T val): ///////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////
testType void testType(T val): ///////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////
testXCHG void testXCHG(T val): ///////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////

Templates

cas template cas(MemoryOrder succ = MemoryOrder.seq, MemoryOrder fail = MemoryOrder.seq): Performs either compare-and-set or compare-and-swap (or exchange).

Examples

int y = 2;
shared int x = y; // OK

//x++; // read modify write error
x.atomicOp!"+="(1); // OK
//y = x; // read error with preview flag
y = x.atomicLoad(); // OK
assert(y == 3);
//x = 5; // write error with preview flag
x.atomicStore(5); // OK
assert(x.atomicLoad() == 5);

core.atomic

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