#include "vl_atomic.h"

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Data Structures
struct	vl_tagged_ptr
	A Tagged Pointer structure for use with Atomic, lock-free algorithms. More...

Macros
#define	vlAtomicPtrInit(atPtr, valPtr) vlAtomicInit((atPtr), valPtr);

#define	vlAtomicPtrCompareExchangeStrong(atPtr, atPtrExpected, valPtr) vlAtomicPtrCompareExchangeStrongExplicit(atPtr, atPtrExpected, valPtr, VL_MEMORY_ORDER_SEQ_CST, VL_MEMORY_ORDER_SEQ_CST)
	Convenience macro for strong atomic tagged pointer CAS with sequential consistency.

#define	vlAtomicPtrCompareExchangeWeak(atPtr, atPtrExpected, valPtr) vlAtomicPtrCompareExchangeWeakExplicit(atPtr, atPtrExpected, valPtr, VL_MEMORY_ORDER_SEQ_CST, VL_MEMORY_ORDER_SEQ_CST)
	Convenience macro for weak atomic tagged pointer CAS with sequential consistency.

Typedefs
typedef VL_ATOMIC vl_tagged_ptr	vl_atomic_ptr
	Atomic variant of vl_tagged_ptr.

Variables
const vl_tagged_ptr	VL_TAGPTR_NULL
	Default initialization value for tagged/atomic pointers.

Data Structure Documentation

◆ vl_tagged_ptr

struct vl_tagged_ptr

A Tagged Pointer structure for use with Atomic, lock-free algorithms.

Using extra state, a tagged pointer helps to distinguish atomic changes to memory to eliminate the ABA problem. The pointer tag is a counter that is incremented with write operation. The tag occupies as many bytes as the native system pointer type.

See also: https://en.wikipedia.org/wiki/ABA_problem

This structure may depend on 128-bit Compare-and-swap on modern platforms to achieve proper atomicity. (Double-width compare-and-swap, aka DWCAS, hardware instruction or similar). Depending on the platform and compiler, it may require an implicit lock.

Collaboration diagram for vl_tagged_ptr:

Data Fields
vl_uintptr_t	ptr
vl_ularge_t	tag

Macro Definition Documentation

◆ vlAtomicPtrCompareExchangeStrong

#define vlAtomicPtrCompareExchangeStrong	(	atPtr,
		atPtrExpected,
		valPtr ) vlAtomicPtrCompareExchangeStrongExplicit(atPtr, atPtrExpected, valPtr, VL_MEMORY_ORDER_SEQ_CST, VL_MEMORY_ORDER_SEQ_CST)

Convenience macro for strong atomic tagged pointer CAS with sequential consistency.

Parameters

atPtr	Pointer to atomic tagged pointer.
atPtrExpected	Expected pointer/tag (updated on failure).
valPtr	New pointer value.

Returns: VL_TRUE if successful, VL_FALSE otherwise.

See also: vlAtomicPtrCompareExchangeStrongExplicit

◆ vlAtomicPtrCompareExchangeWeak

#define vlAtomicPtrCompareExchangeWeak	(	atPtr,
		atPtrExpected,
		valPtr ) vlAtomicPtrCompareExchangeWeakExplicit(atPtr, atPtrExpected, valPtr, VL_MEMORY_ORDER_SEQ_CST, VL_MEMORY_ORDER_SEQ_CST)

Convenience macro for weak atomic tagged pointer CAS with sequential consistency.

Parameters

atPtr	Pointer to atomic tagged pointer.
atPtrExpected	Expected pointer/tag (updated on failure).
valPtr	New pointer value.

Returns: VL_TRUE if successful, VL_FALSE otherwise.

See also: vlAtomicPtrCompareExchangeWeakExplicit

◆ vlAtomicPtrInit

#define vlAtomicPtrInit	(		atPtr,
			valPtr ) vlAtomicInit((atPtr), valPtr);

Typedef Documentation

◆ vl_atomic_ptr

typedef VL_ATOMIC vl_tagged_ptr vl_atomic_ptr

Atomic variant of vl_tagged_ptr.

A Tagged Pointer structure for use with Atomic, lock-free algorithms.

Using extra state, a tagged pointer helps to distinguish atomic changes to memory to eliminate the ABA problem. The pointer tag is a counter that is incremented with write operation. The tag occupies as many bytes as the native system pointer type.

See also: https://en.wikipedia.org/wiki/ABA_problem

This structure may depend on 128-bit Compare-and-swap on modern platforms to achieve proper atomicity. (Double-width compare-and-swap, aka DWCAS, hardware instruction or similar). Depending on the platform and compiler, it may require an implicit lock.

Variable Documentation

◆ VL_TAGPTR_NULL

const vl_tagged_ptr VL_TAGPTR_NULL

extern

Default initialization value for tagged/atomic pointers.

ptr = NULL;

tag = 0;

Data Structures

Macros

Typedefs

Variables