[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);

/*
 * 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 consumer);


/* 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,
				int *wakeup_fd,
				uint64_t *memory_map_size);
extern
int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
			struct channel *chan,
			struct lttng_ust_shm_handle *handle);
extern
int ring_buffer_channel_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
			struct channel *chan,
			struct lttng_ust_shm_handle *handle);
extern
int ring_buffer_stream_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
		struct channel *chan,
		struct lttng_ust_shm_handle *handle,
		int cpu);
extern
int ring_buffer_stream_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
		struct channel *chan,
		struct lttng_ust_shm_handle *handle,
		int cpu);

extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,
				     struct lttng_ust_shm_handle *handle);
extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf,
					 struct lttng_ust_shm_handle *handle);

/*
 * Initialize signals for ring buffer. Should be called early e.g. by
 * main() in the program to affect all threads.
 */
void lib_ringbuffer_signal_init(void);

/*
 * 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
	69	/*
	70	* channel_destroy finalizes all channel's buffers, waits for readers to
	71	* release all references, and destroys the channel.
	72	*/
	73	extern
	74	void channel_destroy(struct channel chan, struct lttng_ust_shm_handle handle,
	75	int consumer);
	76
	77
	78	/* Buffer read operations */
	79
	80	/*
	81	* Iteration on channel cpumask needs to issue a read barrier to match the write
	82	* barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
	83	* buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
	84	* only performed at channel destruction.
	85	*/
	86	#define for_each_channel_cpu(cpu, chan) \
	87	for_each_possible_cpu(cpu)
	88
	89	extern struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer(
	90	const struct lttng_ust_lib_ring_buffer_config *config,
	91	struct channel *chan, int cpu,
	92	struct lttng_ust_shm_handle *handle,
	93	int shm_fd, int wait_fd,
	94	int *wakeup_fd,
	95	uint64_t *memory_map_size);
	96	extern
	97	int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
	98	struct channel *chan,
	99	struct lttng_ust_shm_handle *handle);
	100	extern
	101	int ring_buffer_channel_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
	102	struct channel *chan,
	103	struct lttng_ust_shm_handle *handle);
	104	extern
	105	int ring_buffer_stream_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
	106	struct channel *chan,
	107	struct lttng_ust_shm_handle *handle,
	108	int cpu);
	109	extern
	110	int ring_buffer_stream_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
	111	struct channel *chan,
	112	struct lttng_ust_shm_handle *handle,
	113	int cpu);
	114
	115	extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,
	116	struct lttng_ust_shm_handle *handle);
	117	extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf,
	118	struct lttng_ust_shm_handle *handle);
	119
	120	/*
	121	* Initialize signals for ring buffer. Should be called early e.g. by
	122	* main() in the program to affect all threads.
	123	*/
	124	void lib_ringbuffer_signal_init(void);
	125
	126	/*
	127	* Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
	128	*/
	129	extern int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer *buf,
	130	unsigned long *consumed,
	131	unsigned long *produced,
	132	struct lttng_ust_shm_handle *handle);
	133	extern void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer *buf,
	134	unsigned long consumed_new,
	135	struct lttng_ust_shm_handle *handle);
	136
	137	extern int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	138	unsigned long consumed,
	139	struct lttng_ust_shm_handle *handle);
	140	extern void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	141	struct lttng_ust_shm_handle *handle);
	142
	143	/*
	144	* lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
	145	* to read sub-buffers sequentially.
	146	*/
	147	static inline int lib_ring_buffer_get_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	148	struct lttng_ust_shm_handle *handle)
	149	{
	150	int ret;
	151
	152	ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
	153	&buf->prod_snapshot, handle);
	154	if (ret)
	155	return ret;
	156	ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot, handle);
	157	return ret;
	158	}
	159
	160	static inline
	161	void lib_ring_buffer_put_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
	162	struct lttng_ust_shm_handle *handle)
	163	{
	164	lib_ring_buffer_put_subbuf(buf, handle);
	165	lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
	166	shmp(handle, buf->backend.chan)), handle);
	167	}
	168
	169	extern void channel_reset(struct channel *chan);
	170	extern void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf,
	171	struct lttng_ust_shm_handle *handle);
	172
	173	static inline
	174	unsigned long lib_ring_buffer_get_offset(const struct lttng_ust_lib_ring_buffer_config *config,
	175	struct lttng_ust_lib_ring_buffer *buf)
	176	{
	177	return v_read(config, &buf->offset);
	178	}
	179
	180	static inline
	181	unsigned long lib_ring_buffer_get_consumed(const struct lttng_ust_lib_ring_buffer_config *config,
	182	struct lttng_ust_lib_ring_buffer *buf)
	183	{
	184	return uatomic_read(&buf->consumed);
	185	}
	186
	187	/*
	188	* Must call lib_ring_buffer_is_finalized before reading counters (memory
	189	* ordering enforced with respect to trace teardown).
	190	*/
	191	static inline
	192	int lib_ring_buffer_is_finalized(const struct lttng_ust_lib_ring_buffer_config *config,
	193	struct lttng_ust_lib_ring_buffer *buf)
	194	{
	195	int finalized = CMM_ACCESS_ONCE(buf->finalized);
	196	/*
	197	* Read finalized before counters.
	198	*/
	199	cmm_smp_rmb();
	200	return finalized;
	201	}
	202
	203	static inline
	204	int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
	205	{
	206	return chan->finalized;
	207	}
	208
	209	static inline
	210	int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
	211	{
	212	return uatomic_read(&chan->record_disabled);
	213	}
	214
	215	static inline
	216	unsigned long lib_ring_buffer_get_read_data_size(
	217	const struct lttng_ust_lib_ring_buffer_config *config,
	218	struct lttng_ust_lib_ring_buffer *buf,
	219	struct lttng_ust_shm_handle *handle)
	220	{
	221	return subbuffer_get_read_data_size(config, &buf->backend, handle);
	222	}
	223
	224	static inline
	225	unsigned long lib_ring_buffer_get_records_count(
	226	const struct lttng_ust_lib_ring_buffer_config *config,
	227	struct lttng_ust_lib_ring_buffer *buf)
	228	{
	229	return v_read(config, &buf->records_count);
	230	}
	231
	232	static inline
	233	unsigned long lib_ring_buffer_get_records_overrun(
	234	const struct lttng_ust_lib_ring_buffer_config *config,
	235	struct lttng_ust_lib_ring_buffer *buf)
	236	{
	237	return v_read(config, &buf->records_overrun);
	238	}
	239
	240	static inline
	241	unsigned long lib_ring_buffer_get_records_lost_full(
	242	const struct lttng_ust_lib_ring_buffer_config *config,
	243	struct lttng_ust_lib_ring_buffer *buf)
	244	{
	245	return v_read(config, &buf->records_lost_full);
	246	}
	247
	248	static inline
	249	unsigned long lib_ring_buffer_get_records_lost_wrap(
	250	const struct lttng_ust_lib_ring_buffer_config *config,
	251	struct lttng_ust_lib_ring_buffer *buf)
	252	{
	253	return v_read(config, &buf->records_lost_wrap);
	254	}
	255
	256	static inline
	257	unsigned long lib_ring_buffer_get_records_lost_big(
	258	const struct lttng_ust_lib_ring_buffer_config *config,
	259	struct lttng_ust_lib_ring_buffer *buf)
	260	{
	261	return v_read(config, &buf->records_lost_big);
	262	}
	263
	264	static inline
	265	unsigned long lib_ring_buffer_get_records_read(
	266	const struct lttng_ust_lib_ring_buffer_config *config,
	267	struct lttng_ust_lib_ring_buffer *buf)
	268	{
	269	return v_read(config, &buf->backend.records_read);
	270	}
	271
	272	#endif /* _LTTNG_RING_BUFFER_FRONTEND_H */