atomic_queue.h File Reference

Thread-safe queues. More...

#include <freeradius-devel/util/stdatomic.h>
#include <freeradius-devel/util/talloc.h>

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Typedefs
typedef struct fr_atomic_queue_s	fr_atomic_queue_t
typedef struct fr_atomic_ring_s	fr_atomic_ring_t
	Unbounded segmented single-producer / single-consumer queue.

Functions
void	fr_atomic_queue_debug (FILE *fp, fr_atomic_queue_t *aq)
	Dump an atomic queue.
void	fr_atomic_queue_free (fr_atomic_queue_t **aq)
	Free an atomic queue if it's not freed by ctx.
fr_atomic_queue_t *	fr_atomic_queue_malloc (TALLOC_CTX *ctx, size_t size)
	Create fixed-size atomic queue outside the talloc hierarchy, owned by a talloc context.
bool	fr_atomic_queue_pop (fr_atomic_queue_t *aq, void **p_data)
	Pop a pointer from the atomic queue.
bool	fr_atomic_queue_push (fr_atomic_queue_t *aq, void *data)
	Push a pointer into the atomic queue.
size_t	fr_atomic_queue_size (fr_atomic_queue_t *aq)
fr_atomic_queue_t *	fr_atomic_queue_talloc (TALLOC_CTX *ctx, size_t size)
	Create fixed-size atomic queue.
fr_atomic_ring_t *	fr_atomic_ring_alloc (TALLOC_CTX *ctx, size_t seg_size)
	Allocate an empty SPSC ring.
void	fr_atomic_ring_free (fr_atomic_ring_t **ring)
	Free the ring and all remaining segments.
bool	fr_atomic_ring_pop (fr_atomic_ring_t *ring, void **p_data)
	Pop a pointer from the ring, advancing past drained segments.
bool	fr_atomic_ring_push (fr_atomic_ring_t *ring, void *data)
	Push a pointer into the ring; allocate a new segment on overflow.

Detailed Description

Thread-safe queues.

Id

b98262973a8e27fcfcfee244045609af37750857

Copyright

2016 Alan DeKok (aland.nosp@m.@fre.nosp@m.eradi.nosp@m.us.o.nosp@m.rg)

Definition in file atomic_queue.h.

Typedef Documentation

fr_atomic_queue_t

typedef struct fr_atomic_queue_s fr_atomic_queue_t

Definition at line 40 of file atomic_queue.h.

fr_atomic_ring_t

typedef struct fr_atomic_ring_s fr_atomic_ring_t

Unbounded segmented single-producer / single-consumer queue.

Internally a linked list of fixed-size fr_atomic_queue_t segments. When the producer's current segment fills, a new segment is malloc'd and linked in; the consumer drains segments in order and frees them as it advances. Allocation on the producer side uses raw malloc (not talloc), so the producer thread is free to be one that cannot safely use talloc (e.g. a library-owned callback thread).

Exactly one producer and one consumer. Not safe for MPMC use.

Definition at line 60 of file atomic_queue.h.

Function Documentation

fr_atomic_queue_debug()

void fr_atomic_queue_debug	(	FILE *	fp,
		fr_atomic_queue_t *	aq
	)

Dump an atomic queue.

Absolutely NOT thread-safe.

Parameters

[in]	aq	The atomic queue to debug.
[in]	fp	where the debugging information will be printed.

Definition at line 841 of file atomic_queue.c.

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fr_atomic_queue_free()

void fr_atomic_queue_free

(

fr_atomic_queue_t **

aq

)

Free an atomic queue if it's not freed by ctx.

The queue memory must be cache line aligned, so it lives in one of three places: a talloc aligned array (chunk is the array), a raw allocation owned by a talloc handle (chunk is the handle, whose destructor frees the queue), or a raw allocation with no owner (chunk is NULL).

Definition at line 388 of file atomic_queue.c.

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fr_atomic_queue_malloc()

fr_atomic_queue_t * fr_atomic_queue_malloc	(	TALLOC_CTX *	ctx,
		size_t	size
	)

Create fixed-size atomic queue outside the talloc hierarchy, owned by a talloc context.

The queue itself is a raw posix_memalign allocation, so it can be pushed to and popped from by threads where talloc is not safe, and can later be placed in memory talloc does not manage. A small owner handle allocated in ctx frees the queue when ctx is freed, or when the caller calls fr_atomic_queue_free.

Parameters

[in]	ctx	The talloc ctx which owns the queue.
[in]	size	The number of entries in the queue.

Returns

• NULL on error.
• fr_atomic_queue_t *, a pointer to the allocated and initialized queue.

Definition at line 360 of file atomic_queue.c.

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fr_atomic_queue_pop()

bool fr_atomic_queue_pop	(	fr_atomic_queue_t *	aq,
		void **	p_data
	)

Pop a pointer from the atomic queue.

Parameters

[in]	aq	the atomic queue to retrieve data from.
[out]	p_data	where to write the data.

Returns

• true on successful pop
• false on queue empty

Definition at line 531 of file atomic_queue.c.

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fr_atomic_queue_push()

bool fr_atomic_queue_push	(	fr_atomic_queue_t *	aq,
		void *	data
	)

Push a pointer into the atomic queue.

Parameters

[in]	aq	The atomic queue to add data to.
[in]	data	to push.

Returns

• true on successful push
• false on queue full

Definition at line 408 of file atomic_queue.c.

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fr_atomic_queue_size()

size_t fr_atomic_queue_size

(

fr_atomic_queue_t *

aq

)

Definition at line 593 of file atomic_queue.c.

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fr_atomic_queue_talloc()

fr_atomic_queue_t * fr_atomic_queue_talloc	(	TALLOC_CTX *	ctx,
		size_t	size
	)

Create fixed-size atomic queue.

Note

the queue must be freed explicitly by the ctx being freed, or by using the fr_atomic_queue_free function.

Parameters

[in]	ctx	The talloc ctx to allocate the queue in.
[in]	size	The number of entries in the queue.

Returns

• NULL on error.
• fr_atomic_queue_t *, a pointer to the allocated and initialized queue.

Definition at line 270 of file atomic_queue.c.

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fr_atomic_ring_alloc()

fr_atomic_ring_t * fr_atomic_ring_alloc	(	TALLOC_CTX *	ctx,
		size_t	seg_size
	)

Allocate an empty SPSC ring.

Parameters

[in]	ctx	talloc ctx that owns the ring handle (segments live outside talloc; they are freed by the ring's destructor).
[in]	seg_size	Per-segment capacity. Rounded up to a power of 2.

Returns

• NULL on error.
• A ring containing one initial (empty) segment.

Definition at line 680 of file atomic_queue.c.

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fr_atomic_ring_free()

void fr_atomic_ring_free

(

fr_atomic_ring_t **

ring_p

)

Free the ring and all remaining segments.

Equivalent to talloc_free() on the ring, but nulls the caller's handle in the style of fr_atomic_queue_free.

Definition at line 709 of file atomic_queue.c.

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fr_atomic_ring_pop()

bool fr_atomic_ring_pop	(	fr_atomic_ring_t *	ring,
		void **	p_data
	)

Pop a pointer from the ring, advancing past drained segments.

Single-consumer only. Must not be called concurrently with itself.

Parameters

[in]	ring	Ring to pop from.
[out]	p_data	Where to write the popped value on success.

Returns

• true if a value was popped.
• false if the ring is currently empty.

Definition at line 775 of file atomic_queue.c.

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fr_atomic_ring_push()

bool fr_atomic_ring_push	(	fr_atomic_ring_t *	ring,
		void *	data
	)

Push a pointer into the ring; allocate a new segment on overflow.

Single-producer only. Must not be called concurrently with itself.

Parameters

[in]	ring	Ring to push into.
[in]	data	Value to push (must be non-NULL).

Returns

• true on success.
• false if both the current segment is full and a new segment could not be allocated.

Definition at line 748 of file atomic_queue.c.

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