[lttng-ust.git] / libringbuffer / frontend.h

#ifndef _LINUX_RING_BUFFER_FRONTEND_H
#define _LINUX_RING_BUFFER_FRONTEND_H

/*
 * linux/ringbuffer/frontend.h
 *
 * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * Ring Buffer Library Synchronization Header (API).
 *
 * Author:
 *	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * See ring_buffer_frontend.c for more information on wait-free algorithms.
 *
 * Dual LGPL v2.1/GPL v2 license.
 */

#include <urcu/compiler.h>
#include <urcu/uatomic.h>

#include "smp.h"
/* Internal helpers */
#include "frontend_internal.h"

/* Buffer creation/removal and setup operations */

/*
 * switch_timer_interval is the time interval (in us) to fill sub-buffers with
 * padding to let readers get those sub-buffers.  Used for live streaming.
 *
 * read_timer_interval is the time interval (in us) to wake up pending readers.
 *
 * buf_addr is a pointer the the beginning of the preallocated buffer contiguous
 * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
 * be set to NULL for other backends.
 */

extern
struct shm_handle *channel_create(const struct lib_ring_buffer_config *config,
				const char *name, void *priv,
				void *buf_addr,
				size_t subbuf_size, size_t num_subbuf,
				unsigned int switch_timer_interval,
				unsigned int read_timer_interval,
				int *shm_fd, int *wait_fd,
				uint64_t *memory_map_size);

/* channel_handle_create - for consumer. */
extern
struct shm_handle *channel_handle_create(int shm_fd, int wait_fd,
					uint64_t memory_map_size);

/* channel_handle_add_stream - for consumer. */
extern
int channel_handle_add_stream(struct shm_handle *handle,
		int shm_fd, int wait_fd, uint64_t memory_map_size);

/*
 * channel_destroy returns the private data pointer. It finalizes all channel's
 * buffers, waits for readers to release all references, and destroys the
 * channel.
 */
extern
void *channel_destroy(struct channel *chan, struct shm_handle *handle);


/* Buffer read operations */

/*
 * Iteration on channel cpumask needs to issue a read barrier to match the write
 * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
 * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
 * only performed at channel destruction.
 */
#define for_each_channel_cpu(cpu, chan)					\
	for_each_possible_cpu(cpu)

extern struct lib_ring_buffer *channel_get_ring_buffer(
				const struct lib_ring_buffer_config *config,
				struct channel *chan, int cpu,
				struct shm_handle *handle,
				int *shm_fd, int *wait_fd,
				uint64_t *memory_map_size);
extern int lib_ring_buffer_open_read(struct lib_ring_buffer *buf,
				     struct shm_handle *handle);
extern void lib_ring_buffer_release_read(struct lib_ring_buffer *buf,
					 struct shm_handle *handle);

/*
 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
 */
extern int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf,
				    unsigned long *consumed,
				    unsigned long *produced,
				    struct shm_handle *handle);
extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
					  unsigned long consumed_new,
					  struct shm_handle *handle);

extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf,
				      unsigned long consumed,
				      struct shm_handle *handle);
extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf,
				       struct shm_handle *handle);

/*
 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
 * to read sub-buffers sequentially.
 */
static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer *buf,
						  struct shm_handle *handle)
{
	int ret;

	ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
				       &buf->prod_snapshot, handle);
	if (ret)
		return ret;
	ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot, handle);
	return ret;
}

static inline
void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer *buf,
				     struct shm_handle *handle)
{
	lib_ring_buffer_put_subbuf(buf, handle);
	lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
							shmp(handle, buf->backend.chan)), handle);
}

extern void channel_reset(struct channel *chan);
extern void lib_ring_buffer_reset(struct lib_ring_buffer *buf,
				  struct shm_handle *handle);

static inline
unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config *config,
					 struct lib_ring_buffer *buf)
{
	return v_read(config, &buf->offset);
}

static inline
unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config *config,
					   struct lib_ring_buffer *buf)
{
	return uatomic_read(&buf->consumed);
}

/*
 * Must call lib_ring_buffer_is_finalized before reading counters (memory
 * ordering enforced with respect to trace teardown).
 */
static inline
int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config *config,
				 struct lib_ring_buffer *buf)
{
	int finalized = CMM_ACCESS_ONCE(buf->finalized);
	/*
	 * Read finalized before counters.
	 */
	cmm_smp_rmb();
	return finalized;
}

static inline
int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
{
	return chan->finalized;
}

static inline
int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
{
	return uatomic_read(&chan->record_disabled);
}

static inline
unsigned long lib_ring_buffer_get_read_data_size(
				const struct lib_ring_buffer_config *config,
				struct lib_ring_buffer *buf,
				struct shm_handle *handle)
{
	return subbuffer_get_read_data_size(config, &buf->backend, handle);
}

static inline
unsigned long lib_ring_buffer_get_records_count(
				const struct lib_ring_buffer_config *config,
				struct lib_ring_buffer *buf)
{
	return v_read(config, &buf->records_count);
}

static inline
unsigned long lib_ring_buffer_get_records_overrun(
				const struct lib_ring_buffer_config *config,
				struct lib_ring_buffer *buf)
{
	return v_read(config, &buf->records_overrun);
}

static inline
unsigned long lib_ring_buffer_get_records_lost_full(
				const struct lib_ring_buffer_config *config,
				struct lib_ring_buffer *buf)
{
	return v_read(config, &buf->records_lost_full);
}

static inline
unsigned long lib_ring_buffer_get_records_lost_wrap(
				const struct lib_ring_buffer_config *config,
				struct lib_ring_buffer *buf)
{
	return v_read(config, &buf->records_lost_wrap);
}

static inline
unsigned long lib_ring_buffer_get_records_lost_big(
				const struct lib_ring_buffer_config *config,
				struct lib_ring_buffer *buf)
{
	return v_read(config, &buf->records_lost_big);
}

static inline
unsigned long lib_ring_buffer_get_records_read(
				const struct lib_ring_buffer_config *config,
				struct lib_ring_buffer *buf)
{
	return v_read(config, &buf->backend.records_read);
}

#endif /* _LINUX_RING_BUFFER_FRONTEND_H */
Commit	Line	Data
	1	#ifndef _LINUX_RING_BUFFER_FRONTEND_H
	2	#define _LINUX_RING_BUFFER_FRONTEND_H
	3
	4	/*
	5	* linux/ringbuffer/frontend.h
	6	*
	7	* (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*
	9	* Ring Buffer Library Synchronization Header (API).
	10	*
	11	* Author:
	12	* Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	13	*
	14	* See ring_buffer_frontend.c for more information on wait-free algorithms.
	15	*
	16	* Dual LGPL v2.1/GPL v2 license.
	17	*/
	18
	19	#include <urcu/compiler.h>
	20	#include <urcu/uatomic.h>
	21
	22	#include "smp.h"
	23	/* Internal helpers */
	24	#include "frontend_internal.h"
	25
	26	/* Buffer creation/removal and setup operations */
	27
	28	/*
	29	* switch_timer_interval is the time interval (in us) to fill sub-buffers with
	30	* padding to let readers get those sub-buffers. Used for live streaming.
	31	*
	32	* read_timer_interval is the time interval (in us) to wake up pending readers.
	33	*
	34	* buf_addr is a pointer the the beginning of the preallocated buffer contiguous
	35	* address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
	36	* be set to NULL for other backends.
	37	*/
	38
	39	extern
	40	struct shm_handle channel_create(const struct lib_ring_buffer_config config,
	41	const char name, void priv,
	42	void *buf_addr,
	43	size_t subbuf_size, size_t num_subbuf,
	44	unsigned int switch_timer_interval,
	45	unsigned int read_timer_interval,
	46	int shm_fd, int wait_fd,
	47	uint64_t *memory_map_size);
	48
	49	/* channel_handle_create - for consumer. */
	50	extern
	51	struct shm_handle *channel_handle_create(int shm_fd, int wait_fd,
	52	uint64_t memory_map_size);
	53
	54	/* channel_handle_add_stream - for consumer. */
	55	extern
	56	int channel_handle_add_stream(struct shm_handle *handle,
	57	int shm_fd, int wait_fd, uint64_t memory_map_size);
	58
	59	/*
	60	* channel_destroy returns the private data pointer. It finalizes all channel's
	61	* buffers, waits for readers to release all references, and destroys the
	62	* channel.
	63	*/
	64	extern
	65	void channel_destroy(struct channel chan, struct shm_handle *handle);
	66
	67
	68	/* Buffer read operations */
	69
	70	/*
	71	* Iteration on channel cpumask needs to issue a read barrier to match the write
	72	* barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
	73	* buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
	74	* only performed at channel destruction.
	75	*/
	76	#define for_each_channel_cpu(cpu, chan) \
	77	for_each_possible_cpu(cpu)
	78
	79	extern struct lib_ring_buffer *channel_get_ring_buffer(
	80	const struct lib_ring_buffer_config *config,
	81	struct channel *chan, int cpu,
	82	struct shm_handle *handle,
	83	int shm_fd, int wait_fd,
	84	uint64_t *memory_map_size);
	85	extern int lib_ring_buffer_open_read(struct lib_ring_buffer *buf,
	86	struct shm_handle *handle);
	87	extern void lib_ring_buffer_release_read(struct lib_ring_buffer *buf,
	88	struct shm_handle *handle);
	89
	90	/*
	91	* Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
	92	*/
	93	extern int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf,
	94	unsigned long *consumed,
	95	unsigned long *produced,
	96	struct shm_handle *handle);
	97	extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
	98	unsigned long consumed_new,
	99	struct shm_handle *handle);
	100
	101	extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf,
	102	unsigned long consumed,
	103	struct shm_handle *handle);
	104	extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf,
	105	struct shm_handle *handle);
	106
	107	/*
	108	* lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
	109	* to read sub-buffers sequentially.
	110	*/
	111	static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer *buf,
	112	struct shm_handle *handle)
	113	{
	114	int ret;
	115
	116	ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
	117	&buf->prod_snapshot, handle);
	118	if (ret)
	119	return ret;
	120	ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot, handle);
	121	return ret;
	122	}
	123
	124	static inline
	125	void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer *buf,
	126	struct shm_handle *handle)
	127	{
	128	lib_ring_buffer_put_subbuf(buf, handle);
	129	lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
	130	shmp(handle, buf->backend.chan)), handle);
	131	}
	132
	133	extern void channel_reset(struct channel *chan);
	134	extern void lib_ring_buffer_reset(struct lib_ring_buffer *buf,
	135	struct shm_handle *handle);
	136
	137	static inline
	138	unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config *config,
	139	struct lib_ring_buffer *buf)
	140	{
	141	return v_read(config, &buf->offset);
	142	}
	143
	144	static inline
	145	unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config *config,
	146	struct lib_ring_buffer *buf)
	147	{
	148	return uatomic_read(&buf->consumed);
	149	}
	150
	151	/*
	152	* Must call lib_ring_buffer_is_finalized before reading counters (memory
	153	* ordering enforced with respect to trace teardown).
	154	*/
	155	static inline
	156	int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config *config,
	157	struct lib_ring_buffer *buf)
	158	{
	159	int finalized = CMM_ACCESS_ONCE(buf->finalized);
	160	/*
	161	* Read finalized before counters.
	162	*/
	163	cmm_smp_rmb();
	164	return finalized;
	165	}
	166
	167	static inline
	168	int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
	169	{
	170	return chan->finalized;
	171	}
	172
	173	static inline
	174	int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
	175	{
	176	return uatomic_read(&chan->record_disabled);
	177	}
	178
	179	static inline
	180	unsigned long lib_ring_buffer_get_read_data_size(
	181	const struct lib_ring_buffer_config *config,
	182	struct lib_ring_buffer *buf,
	183	struct shm_handle *handle)
	184	{
	185	return subbuffer_get_read_data_size(config, &buf->backend, handle);
	186	}
	187
	188	static inline
	189	unsigned long lib_ring_buffer_get_records_count(
	190	const struct lib_ring_buffer_config *config,
	191	struct lib_ring_buffer *buf)
	192	{
	193	return v_read(config, &buf->records_count);
	194	}
	195
	196	static inline
	197	unsigned long lib_ring_buffer_get_records_overrun(
	198	const struct lib_ring_buffer_config *config,
	199	struct lib_ring_buffer *buf)
	200	{
	201	return v_read(config, &buf->records_overrun);
	202	}
	203
	204	static inline
	205	unsigned long lib_ring_buffer_get_records_lost_full(
	206	const struct lib_ring_buffer_config *config,
	207	struct lib_ring_buffer *buf)
	208	{
	209	return v_read(config, &buf->records_lost_full);
	210	}
	211
	212	static inline
	213	unsigned long lib_ring_buffer_get_records_lost_wrap(
	214	const struct lib_ring_buffer_config *config,
	215	struct lib_ring_buffer *buf)
	216	{
	217	return v_read(config, &buf->records_lost_wrap);
	218	}
	219
	220	static inline
	221	unsigned long lib_ring_buffer_get_records_lost_big(
	222	const struct lib_ring_buffer_config *config,
	223	struct lib_ring_buffer *buf)
	224	{
	225	return v_read(config, &buf->records_lost_big);
	226	}
	227
	228	static inline
	229	unsigned long lib_ring_buffer_get_records_read(
	230	const struct lib_ring_buffer_config *config,
	231	struct lib_ring_buffer *buf)
	232	{
	233	return v_read(config, &buf->backend.records_read);
	234	}
	235
	236	#endif /* _LINUX_RING_BUFFER_FRONTEND_H */