atomic_queue.c File Reference

Thread-safe queues. More...

#include <stdint.h>
#include <stdalign.h>
#include <inttypes.h>
#include <freeradius-devel/autoconf.h>
#include <freeradius-devel/io/atomic_queue.h>
#include <freeradius-devel/util/talloc.h>

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Data Structures
struct	fr_atomic_queue_entry_t
	Entry in the queue. More...
struct	fr_atomic_queue_s
	Structure to hold the atomic queue. More...

Macros
#define	CACHE_LINE_SIZE   64

Functions
fr_atomic_queue_t *	fr_atomic_queue_alloc (TALLOC_CTX *ctx, size_t size)
	Create fixed-size atomic queue. More...
void	fr_atomic_queue_debug (fr_atomic_queue_t *aq, FILE *fp)
	Dump an atomic queue. More...
void	fr_atomic_queue_free (fr_atomic_queue_t **aq)
	Free an atomic queue if it's not freed by ctx. More...
bool	fr_atomic_queue_pop (fr_atomic_queue_t *aq, void **p_data)
	Pop a pointer from the atomic queue. More...
bool	fr_atomic_queue_push (fr_atomic_queue_t *aq, void *data)
	Push a pointer into the atomic queue. More...
size_t	fr_atomic_queue_size (fr_atomic_queue_t *aq)

Detailed Description

Thread-safe queues.

Id

4c9b7eac8aec45848041939320b3ab29e966ff9f

Copyright

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

2016 Alister Winfield

Definition in file atomic_queue.c.

---

Data Structure Documentation

fr_atomic_queue_entry_t

struct fr_atomic_queue_entry_t

Entry in the queue.

Note

This structure is cache line aligned for modern AMD/Intel CPUs. This is to avoid contention when the producer and consumer are executing on different CPU cores.

Definition at line 44 of file atomic_queue.c.

Data Fields
void *	data
atomic_int64_t	seq	Must be seq then data to ensure seq is 64bit aligned for 32bit address spaces.

fr_atomic_queue_s

struct fr_atomic_queue_s

Structure to hold the atomic queue.

Definition at line 54 of file atomic_queue.c.

Collaboration diagram for fr_atomic_queue_s:

Data Fields
void *	chunk	To pass to free. The non-aligned address.
fr_atomic_queue_entry_t	entry[]	The entry array, also aligned to ensure it's not in the same cache line as tail and size.
atomic_int64_t	head	Head, aligned bytes to ensure it's in a different cache line to tail to reduce memory contention.
size_t	size
atomic_int64_t	tail

Macro Definition Documentation

CACHE_LINE_SIZE

#define CACHE_LINE_SIZE   64

Definition at line 36 of file atomic_queue.c.

Function Documentation

fr_atomic_queue_alloc()

fr_atomic_queue_t* fr_atomic_queue_alloc	(	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 80 of file atomic_queue.c.

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fr_atomic_queue_debug()

void fr_atomic_queue_debug	(	fr_atomic_queue_t *	aq,
		FILE *	fp
	)

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 301 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.

This function is needed because the atomic queue memory must be cache line aligned.

Definition at line 132 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 215 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 148 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 265 of file atomic_queue.c.

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