[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.
 *
 * priv_data (output) is set to a pointer into a "priv_data_len"-sized
 * memory area for client-specific data. This memory is managed by lib
 * ring buffer. priv_data_align is the alignment required for the
 * private data area.
 */

extern
struct lttng_ust_shm_handle *channel_create(const struct lttng_ust_lib_ring_buffer_config *config,
				const char *name,
				void **priv_data,
				size_t priv_data_align,
				size_t priv_data_size,
				void *priv_data_init,
				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 lttng_ust_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 lttng_ust_shm_handle *handle,
		int shm_fd, int wait_fd, uint64_t memory_map_size);

/*
 * channel_destroy finalizes all channel's buffers, waits for readers to
 * release all references, and destroys the channel.
 */
extern
void channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle,
		int shadow);


/* 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 lttng_ust_lib_ring_buffer *channel_get_ring_buffer(
				const struct lttng_ust_lib_ring_buffer_config *config,
				struct channel *chan, int cpu,
				struct lttng_ust_shm_handle *handle,
				int **shm_fd, int **wait_fd,
				uint64_t **memory_map_size);
extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,
				     struct lttng_ust_shm_handle *handle,
				     int shadow);
extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf,
					 struct lttng_ust_shm_handle *handle,
					 int shadow);

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

extern int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf,
				      unsigned long consumed,
				      struct lttng_ust_shm_handle *handle);
extern void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf,
				       struct lttng_ust_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 lttng_ust_lib_ring_buffer *buf,
						  struct lttng_ust_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 lttng_ust_lib_ring_buffer *buf,
				     struct lttng_ust_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 lttng_ust_lib_ring_buffer *buf,
				  struct lttng_ust_shm_handle *handle);

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

static inline
unsigned long lib_ring_buffer_get_consumed(const struct lttng_ust_lib_ring_buffer_config *config,
					   struct lttng_ust_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 lttng_ust_lib_ring_buffer_config *config,
				 struct lttng_ust_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 lttng_ust_lib_ring_buffer_config *config,
				struct lttng_ust_lib_ring_buffer *buf,
				struct lttng_ust_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 lttng_ust_lib_ring_buffer_config *config,
				struct lttng_ust_lib_ring_buffer *buf)
{
	return v_read(config, &buf->records_count);
}

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

static inline
unsigned long lib_ring_buffer_get_records_lost_full(
				const struct lttng_ust_lib_ring_buffer_config *config,
				struct lttng_ust_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 lttng_ust_lib_ring_buffer_config *config,
				struct lttng_ust_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 lttng_ust_lib_ring_buffer_config *config,
				struct lttng_ust_lib_ring_buffer *buf)
{
	return v_read(config, &buf->records_lost_big);
}

static inline
unsigned long lib_ring_buffer_get_records_read(
				const struct lttng_ust_lib_ring_buffer_config *config,
				struct lttng_ust_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	* priv_data (output) is set to a pointer into a "priv_data_len"-sized
	39	* memory area for client-specific data. This memory is managed by lib
	40	* ring buffer. priv_data_align is the alignment required for the
	41	* private data area.
	42	*/
	43
	44	extern
	45	struct lttng_ust_shm_handle channel_create(const struct lttng_ust_lib_ring_buffer_config config,
	46	const char *name,
	47	void **priv_data,
	48	size_t priv_data_align,
	49	size_t priv_data_size,
	50	void *priv_data_init,
	51	void *buf_addr,
	52	size_t subbuf_size, size_t num_subbuf,
	53	unsigned int switch_timer_interval,
	54	unsigned int read_timer_interval,
	55	int shm_fd, int wait_fd,
	56	uint64_t **memory_map_size);
	57
	58	/* channel_handle_create - for consumer. */
	59	extern
	60	struct lttng_ust_shm_handle *channel_handle_create(int shm_fd, int wait_fd,
	61	uint64_t memory_map_size);
	62
	63	/* channel_handle_add_stream - for consumer. */
	64	extern
	65	int channel_handle_add_stream(struct lttng_ust_shm_handle *handle,
	66	int shm_fd, int wait_fd, uint64_t memory_map_size);
	67
	68	/*
	69	* channel_destroy finalizes all channel's buffers, waits for readers to
	70	* release all references, and destroys the channel.
	71	*/
	72	extern
	73	void channel_destroy(struct channel chan, struct lttng_ust_shm_handle handle,
	74	int shadow);
	75
	76
	77	/* Buffer read operations */
	78
	79	/*
	80	* Iteration on channel cpumask needs to issue a read barrier to match the write
	81	* barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
	82	* buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
	83	* only performed at channel destruction.
	84	*/
	85	#define for_each_channel_cpu(cpu, chan) \
	86	for_each_possible_cpu(cpu)
	87
	88	extern struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer(
	89	const struct lttng_ust_lib_ring_buffer_config *config,
	90	struct channel *chan, int cpu,
	91	struct lttng_ust_shm_handle *handle,
	92	int shm_fd, int wait_fd,
	93	uint64_t **memory_map_size);
	94	extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,
	95	struct lttng_ust_shm_handle *handle,
	96	int shadow);
	97	extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf,
	98	struct lttng_ust_shm_handle *handle,
	99	int shadow);
	100
	101	/*
	102	* Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
	103	*/
	104	extern int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer *buf,
	105	unsigned long *consumed,
	106	unsigned long *produced,
	107	struct lttng_ust_shm_handle *handle);
	108	extern void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer *buf,
	109	unsigned long consumed_new,
	110	struct lttng_ust_shm_handle *handle);
	111
	112	extern int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	113	unsigned long consumed,
	114	struct lttng_ust_shm_handle *handle);
	115	extern void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	116	struct lttng_ust_shm_handle *handle);
	117
	118	/*
	119	* lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
	120	* to read sub-buffers sequentially.
	121	*/
	122	static inline int lib_ring_buffer_get_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	123	struct lttng_ust_shm_handle *handle)
	124	{
	125	int ret;
	126
	127	ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
	128	&buf->prod_snapshot, handle);
	129	if (ret)
	130	return ret;
	131	ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot, handle);
	132	return ret;
	133	}
	134
	135	static inline
	136	void lib_ring_buffer_put_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	137	struct lttng_ust_shm_handle *handle)
	138	{
	139	lib_ring_buffer_put_subbuf(buf, handle);
	140	lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
	141	shmp(handle, buf->backend.chan)), handle);
	142	}
	143
	144	extern void channel_reset(struct channel *chan);
	145	extern void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf,
	146	struct lttng_ust_shm_handle *handle);
	147
	148	static inline
	149	unsigned long lib_ring_buffer_get_offset(const struct lttng_ust_lib_ring_buffer_config *config,
	150	struct lttng_ust_lib_ring_buffer *buf)
	151	{
	152	return v_read(config, &buf->offset);
	153	}
	154
	155	static inline
	156	unsigned long lib_ring_buffer_get_consumed(const struct lttng_ust_lib_ring_buffer_config *config,
	157	struct lttng_ust_lib_ring_buffer *buf)
	158	{
	159	return uatomic_read(&buf->consumed);
	160	}
	161
	162	/*
	163	* Must call lib_ring_buffer_is_finalized before reading counters (memory
	164	* ordering enforced with respect to trace teardown).
	165	*/
	166	static inline
	167	int lib_ring_buffer_is_finalized(const struct lttng_ust_lib_ring_buffer_config *config,
	168	struct lttng_ust_lib_ring_buffer *buf)
	169	{
	170	int finalized = CMM_ACCESS_ONCE(buf->finalized);
	171	/*
	172	* Read finalized before counters.
	173	*/
	174	cmm_smp_rmb();
	175	return finalized;
	176	}
	177
	178	static inline
	179	int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
	180	{
	181	return chan->finalized;
	182	}
	183
	184	static inline
	185	int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
	186	{
	187	return uatomic_read(&chan->record_disabled);
	188	}
	189
	190	static inline
	191	unsigned long lib_ring_buffer_get_read_data_size(
	192	const struct lttng_ust_lib_ring_buffer_config *config,
	193	struct lttng_ust_lib_ring_buffer *buf,
	194	struct lttng_ust_shm_handle *handle)
	195	{
	196	return subbuffer_get_read_data_size(config, &buf->backend, handle);
	197	}
	198
	199	static inline
	200	unsigned long lib_ring_buffer_get_records_count(
	201	const struct lttng_ust_lib_ring_buffer_config *config,
	202	struct lttng_ust_lib_ring_buffer *buf)
	203	{
	204	return v_read(config, &buf->records_count);
	205	}
	206
	207	static inline
	208	unsigned long lib_ring_buffer_get_records_overrun(
	209	const struct lttng_ust_lib_ring_buffer_config *config,
	210	struct lttng_ust_lib_ring_buffer *buf)
	211	{
	212	return v_read(config, &buf->records_overrun);
	213	}
	214
	215	static inline
	216	unsigned long lib_ring_buffer_get_records_lost_full(
	217	const struct lttng_ust_lib_ring_buffer_config *config,
	218	struct lttng_ust_lib_ring_buffer *buf)
	219	{
	220	return v_read(config, &buf->records_lost_full);
	221	}
	222
	223	static inline
	224	unsigned long lib_ring_buffer_get_records_lost_wrap(
	225	const struct lttng_ust_lib_ring_buffer_config *config,
	226	struct lttng_ust_lib_ring_buffer *buf)
	227	{
	228	return v_read(config, &buf->records_lost_wrap);
	229	}
	230
	231	static inline
	232	unsigned long lib_ring_buffer_get_records_lost_big(
	233	const struct lttng_ust_lib_ring_buffer_config *config,
	234	struct lttng_ust_lib_ring_buffer *buf)
	235	{
	236	return v_read(config, &buf->records_lost_big);
	237	}
	238
	239	static inline
	240	unsigned long lib_ring_buffer_get_records_read(
	241	const struct lttng_ust_lib_ring_buffer_config *config,
	242	struct lttng_ust_lib_ring_buffer *buf)
	243	{
	244	return v_read(config, &buf->backend.records_read);
	245	}
	246
	247	#endif /* _LINUX_RING_BUFFER_FRONTEND_H */