[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);

/*
 * 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
852c2936 MD	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
14641deb MD	19	#include <urcu/compiler.h>
	20	#include <urcu/uatomic.h>
	21
a6352fd4	22	#include "smp.h"
852c2936	23	/* Internal helpers */
4931a13e	24	#include "frontend_internal.h"
852c2936 MD	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
431d5cf0 MD	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);
852c2936 MD	46
	47	/*
	48	* channel_destroy returns the private data pointer. It finalizes all channel's
	49	* buffers, waits for readers to release all references, and destroys the
	50	* channel.
	51	*/
	52	extern
1d498196	53	void channel_destroy(struct channel chan, struct shm_handle *handle);
852c2936 MD	54
	55
	56	/* Buffer read operations */
	57
	58	/*
	59	* Iteration on channel cpumask needs to issue a read barrier to match the write
	60	* barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
	61	* buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
	62	* only performed at channel destruction.
	63	*/
	64	#define for_each_channel_cpu(cpu, chan) \
a6352fd4	65	for_each_possible_cpu(cpu)
852c2936 MD	66
	67	extern struct lib_ring_buffer *channel_get_ring_buffer(
	68	const struct lib_ring_buffer_config *config,
1d498196	69	struct channel *chan, int cpu,
381c0f1e MD	70	struct shm_handle *handle,
	71	int shm_fd, int wait_fd,
	72	uint64_t *memory_map_size);
1d498196 MD	73	extern int lib_ring_buffer_open_read(struct lib_ring_buffer *buf,
	74	struct shm_handle *handle);
	75	extern void lib_ring_buffer_release_read(struct lib_ring_buffer *buf,
	76	struct shm_handle *handle);
852c2936 MD	77
	78	/*
	79	* Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
	80	*/
	81	extern int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf,
	82	unsigned long *consumed,
1d498196 MD	83	unsigned long *produced,
1d498196 MD	84	struct shm_handle *handle);
852c2936	85	extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
1d498196 MD	86	unsigned long consumed_new,
1d498196 MD	87	struct shm_handle *handle);
852c2936 MD	88
852c2936 MD	89	extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf,
1d498196 MD	90	unsigned long consumed,
	91	struct shm_handle *handle);
	92	extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf,
	93	struct shm_handle *handle);
852c2936 MD	94
	95	/*
	96	* lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
	97	* to read sub-buffers sequentially.
	98	*/
1d498196 MD	99	static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer *buf,
1d498196 MD	100	struct shm_handle *handle)
852c2936 MD	101	{
	102	int ret;
	103
	104	ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
1d498196	105	&buf->prod_snapshot, handle);
852c2936 MD	106	if (ret)
852c2936 MD	107	return ret;
1d498196	108	ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot, handle);
852c2936 MD	109	return ret;
	110	}
	111
1d498196 MD	112	static inline
	113	void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer *buf,
	114	struct shm_handle *handle)
852c2936	115	{
1d498196	116	lib_ring_buffer_put_subbuf(buf, handle);
852c2936	117	lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
1d498196	118	shmp(handle, buf->backend.chan)), handle);
852c2936 MD	119	}
	120
	121	extern void channel_reset(struct channel *chan);
1d498196 MD	122	extern void lib_ring_buffer_reset(struct lib_ring_buffer *buf,
1d498196 MD	123	struct shm_handle *handle);
852c2936 MD	124
	125	static inline
	126	unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config *config,
	127	struct lib_ring_buffer *buf)
	128	{
	129	return v_read(config, &buf->offset);
	130	}
	131
	132	static inline
	133	unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config *config,
	134	struct lib_ring_buffer *buf)
	135	{
14641deb	136	return uatomic_read(&buf->consumed);
852c2936 MD	137	}
	138
	139	/*
	140	* Must call lib_ring_buffer_is_finalized before reading counters (memory
	141	* ordering enforced with respect to trace teardown).
	142	*/
	143	static inline
	144	int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config *config,
	145	struct lib_ring_buffer *buf)
	146	{
14641deb	147	int finalized = CMM_ACCESS_ONCE(buf->finalized);
852c2936 MD	148	/*
	149	* Read finalized before counters.
	150	*/
14641deb	151	cmm_smp_rmb();
852c2936 MD	152	return finalized;
	153	}
	154
	155	static inline
	156	int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
	157	{
	158	return chan->finalized;
	159	}
	160
	161	static inline
	162	int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
	163	{
14641deb	164	return uatomic_read(&chan->record_disabled);
852c2936 MD	165	}
	166
	167	static inline
	168	unsigned long lib_ring_buffer_get_read_data_size(
	169	const struct lib_ring_buffer_config *config,
1d498196 MD	170	struct lib_ring_buffer *buf,
1d498196 MD	171	struct shm_handle *handle)
852c2936	172	{
1d498196	173	return subbuffer_get_read_data_size(config, &buf->backend, handle);
852c2936 MD	174	}
	175
	176	static inline
	177	unsigned long lib_ring_buffer_get_records_count(
	178	const struct lib_ring_buffer_config *config,
	179	struct lib_ring_buffer *buf)
	180	{
	181	return v_read(config, &buf->records_count);
	182	}
	183
	184	static inline
	185	unsigned long lib_ring_buffer_get_records_overrun(
	186	const struct lib_ring_buffer_config *config,
	187	struct lib_ring_buffer *buf)
	188	{
	189	return v_read(config, &buf->records_overrun);
	190	}
	191
	192	static inline
	193	unsigned long lib_ring_buffer_get_records_lost_full(
	194	const struct lib_ring_buffer_config *config,
	195	struct lib_ring_buffer *buf)
	196	{
	197	return v_read(config, &buf->records_lost_full);
	198	}
	199
	200	static inline
	201	unsigned long lib_ring_buffer_get_records_lost_wrap(
	202	const struct lib_ring_buffer_config *config,
	203	struct lib_ring_buffer *buf)
	204	{
	205	return v_read(config, &buf->records_lost_wrap);
	206	}
	207
	208	static inline
	209	unsigned long lib_ring_buffer_get_records_lost_big(
	210	const struct lib_ring_buffer_config *config,
	211	struct lib_ring_buffer *buf)
	212	{
	213	return v_read(config, &buf->records_lost_big);
	214	}
	215
	216	static inline
	217	unsigned long lib_ring_buffer_get_records_read(
	218	const struct lib_ring_buffer_config *config,
	219	struct lib_ring_buffer *buf)
	220	{
	221	return v_read(config, &buf->backend.records_read);
	222	}
	223
	224	#endif /* _LINUX_RING_BUFFER_FRONTEND_H */