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