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

#ifndef _LTTNG_RING_BUFFER_FRONTEND_H
#define _LTTNG_RING_BUFFER_FRONTEND_H

/*
 * libringbuffer/frontend.h
 *
 * Ring Buffer Library Synchronization Header (API).
 *
 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 *
 * Author:
 *	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * See ring_buffer_frontend.c for more information on wait-free algorithms.
 */

#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, char **shm_path,
				int **wait_fd, char **wait_pipe_path,
				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, char **shm_path,
				int **wait_fd, char **wait_pipe_path,
				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 /* _LTTNG_RING_BUFFER_FRONTEND_H */
Commit	Line	Data
	1	#ifndef _LTTNG_RING_BUFFER_FRONTEND_H
	2	#define _LTTNG_RING_BUFFER_FRONTEND_H
	3
	4	/*
	5	* libringbuffer/frontend.h
	6	*
	7	* Ring Buffer Library Synchronization Header (API).
	8	*
	9	* Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	10	*
	11	* This library is free software; you can redistribute it and/or
	12	* modify it under the terms of the GNU Lesser General Public
	13	* License as published by the Free Software Foundation; only
	14	* version 2.1 of the License.
	15	*
	16	* This library is distributed in the hope that it will be useful,
	17	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	18	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	19	* Lesser General Public License for more details.
	20	*
	21	* You should have received a copy of the GNU Lesser General Public
	22	* License along with this library; if not, write to the Free Software
	23	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	24	*
	25	*
	26	* Author:
	27	* Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	28	*
	29	* See ring_buffer_frontend.c for more information on wait-free algorithms.
	30	*/
	31
	32	#include <urcu/compiler.h>
	33	#include <urcu/uatomic.h>
	34
	35	#include "smp.h"
	36	/* Internal helpers */
	37	#include "frontend_internal.h"
	38
	39	/* Buffer creation/removal and setup operations */
	40
	41	/*
	42	* switch_timer_interval is the time interval (in us) to fill sub-buffers with
	43	* padding to let readers get those sub-buffers. Used for live streaming.
	44	*
	45	* read_timer_interval is the time interval (in us) to wake up pending readers.
	46	*
	47	* buf_addr is a pointer the the beginning of the preallocated buffer contiguous
	48	* address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
	49	* be set to NULL for other backends.
	50	*
	51	* priv_data (output) is set to a pointer into a "priv_data_len"-sized
	52	* memory area for client-specific data. This memory is managed by lib
	53	* ring buffer. priv_data_align is the alignment required for the
	54	* private data area.
	55	*/
	56
	57	extern
	58	struct lttng_ust_shm_handle channel_create(const struct lttng_ust_lib_ring_buffer_config config,
	59	const char *name,
	60	void **priv_data,
	61	size_t priv_data_align,
	62	size_t priv_data_size,
	63	void *priv_data_init,
	64	void *buf_addr,
	65	size_t subbuf_size, size_t num_subbuf,
	66	unsigned int switch_timer_interval,
	67	unsigned int read_timer_interval,
	68	int shm_fd, char shm_path,
	69	int wait_fd, char wait_pipe_path,
	70	uint64_t **memory_map_size);
	71
	72	/* channel_handle_create - for consumer. */
	73	extern
	74	struct lttng_ust_shm_handle *channel_handle_create(int shm_fd, int wait_fd,
	75	uint64_t memory_map_size);
	76
	77	/* channel_handle_add_stream - for consumer. */
	78	extern
	79	int channel_handle_add_stream(struct lttng_ust_shm_handle *handle,
	80	int shm_fd, int wait_fd, uint64_t memory_map_size);
	81
	82	/*
	83	* channel_destroy finalizes all channel's buffers, waits for readers to
	84	* release all references, and destroys the channel.
	85	*/
	86	extern
	87	void channel_destroy(struct channel chan, struct lttng_ust_shm_handle handle,
	88	int shadow);
	89
	90
	91	/* Buffer read operations */
	92
	93	/*
	94	* Iteration on channel cpumask needs to issue a read barrier to match the write
	95	* barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
	96	* buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
	97	* only performed at channel destruction.
	98	*/
	99	#define for_each_channel_cpu(cpu, chan) \
	100	for_each_possible_cpu(cpu)
	101
	102	extern struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer(
	103	const struct lttng_ust_lib_ring_buffer_config *config,
	104	struct channel *chan, int cpu,
	105	struct lttng_ust_shm_handle *handle,
	106	int shm_fd, char shm_path,
	107	int wait_fd, char wait_pipe_path,
	108	uint64_t **memory_map_size);
	109	extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,
	110	struct lttng_ust_shm_handle *handle,
	111	int shadow);
	112	extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf,
	113	struct lttng_ust_shm_handle *handle,
	114	int shadow);
	115
	116	/*
	117	* Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
	118	*/
	119	extern int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer *buf,
	120	unsigned long *consumed,
	121	unsigned long *produced,
	122	struct lttng_ust_shm_handle *handle);
	123	extern void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer *buf,
	124	unsigned long consumed_new,
	125	struct lttng_ust_shm_handle *handle);
	126
	127	extern int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	128	unsigned long consumed,
	129	struct lttng_ust_shm_handle *handle);
	130	extern void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	131	struct lttng_ust_shm_handle *handle);
	132
	133	/*
	134	* lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
	135	* to read sub-buffers sequentially.
	136	*/
	137	static inline int lib_ring_buffer_get_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	138	struct lttng_ust_shm_handle *handle)
	139	{
	140	int ret;
	141
	142	ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
	143	&buf->prod_snapshot, handle);
	144	if (ret)
	145	return ret;
	146	ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot, handle);
	147	return ret;
	148	}
	149
	150	static inline
	151	void lib_ring_buffer_put_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	152	struct lttng_ust_shm_handle *handle)
	153	{
	154	lib_ring_buffer_put_subbuf(buf, handle);
	155	lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
	156	shmp(handle, buf->backend.chan)), handle);
	157	}
	158
	159	extern void channel_reset(struct channel *chan);
	160	extern void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf,
	161	struct lttng_ust_shm_handle *handle);
	162
	163	static inline
	164	unsigned long lib_ring_buffer_get_offset(const struct lttng_ust_lib_ring_buffer_config *config,
	165	struct lttng_ust_lib_ring_buffer *buf)
	166	{
	167	return v_read(config, &buf->offset);
	168	}
	169
	170	static inline
	171	unsigned long lib_ring_buffer_get_consumed(const struct lttng_ust_lib_ring_buffer_config *config,
	172	struct lttng_ust_lib_ring_buffer *buf)
	173	{
	174	return uatomic_read(&buf->consumed);
	175	}
	176
	177	/*
	178	* Must call lib_ring_buffer_is_finalized before reading counters (memory
	179	* ordering enforced with respect to trace teardown).
	180	*/
	181	static inline
	182	int lib_ring_buffer_is_finalized(const struct lttng_ust_lib_ring_buffer_config *config,
	183	struct lttng_ust_lib_ring_buffer *buf)
	184	{
	185	int finalized = CMM_ACCESS_ONCE(buf->finalized);
	186	/*
	187	* Read finalized before counters.
	188	*/
	189	cmm_smp_rmb();
	190	return finalized;
	191	}
	192
	193	static inline
	194	int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
	195	{
	196	return chan->finalized;
	197	}
	198
	199	static inline
	200	int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
	201	{
	202	return uatomic_read(&chan->record_disabled);
	203	}
	204
	205	static inline
	206	unsigned long lib_ring_buffer_get_read_data_size(
	207	const struct lttng_ust_lib_ring_buffer_config *config,
	208	struct lttng_ust_lib_ring_buffer *buf,
	209	struct lttng_ust_shm_handle *handle)
	210	{
	211	return subbuffer_get_read_data_size(config, &buf->backend, handle);
	212	}
	213
	214	static inline
	215	unsigned long lib_ring_buffer_get_records_count(
	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_count);
	220	}
	221
	222	static inline
	223	unsigned long lib_ring_buffer_get_records_overrun(
	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_overrun);
	228	}
	229
	230	static inline
	231	unsigned long lib_ring_buffer_get_records_lost_full(
	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_full);
	236	}
	237
	238	static inline
	239	unsigned long lib_ring_buffer_get_records_lost_wrap(
	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->records_lost_wrap);
	244	}
	245
	246	static inline
	247	unsigned long lib_ring_buffer_get_records_lost_big(
	248	const struct lttng_ust_lib_ring_buffer_config *config,
	249	struct lttng_ust_lib_ring_buffer *buf)
	250	{
	251	return v_read(config, &buf->records_lost_big);
	252	}
	253
	254	static inline
	255	unsigned long lib_ring_buffer_get_records_read(
	256	const struct lttng_ust_lib_ring_buffer_config *config,
	257	struct lttng_ust_lib_ring_buffer *buf)
	258	{
	259	return v_read(config, &buf->backend.records_read);
	260	}
	261
	262	#endif /* _LTTNG_RING_BUFFER_FRONTEND_H */