1 #ifndef _LTTNG_RING_BUFFER_FRONTEND_H
2 #define _LTTNG_RING_BUFFER_FRONTEND_H
5 * libringbuffer/frontend.h
7 * Ring Buffer Library Synchronization Header (API).
9 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
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.
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
27 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
29 * See ring_buffer_frontend.c for more information on wait-free algorithms.
32 #include <urcu/compiler.h>
33 #include <urcu/uatomic.h>
36 /* Internal helpers */
37 #include "frontend_internal.h"
39 /* Buffer creation/removal and setup operations */
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.
45 * read_timer_interval is the time interval (in us) to wake up pending readers.
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.
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
58 struct lttng_ust_shm_handle
*channel_create(const struct lttng_ust_lib_ring_buffer_config
*config
,
61 size_t priv_data_align
,
62 size_t priv_data_size
,
65 size_t subbuf_size
, size_t num_subbuf
,
66 unsigned int switch_timer_interval
,
67 unsigned int read_timer_interval
,
68 const int *stream_fds
, int nr_stream_fds
);
71 * channel_destroy finalizes all channel's buffers, waits for readers to
72 * release all references, and destroys the channel.
75 void channel_destroy(struct channel
*chan
, struct lttng_ust_shm_handle
*handle
,
79 /* Buffer read operations */
82 * Iteration on channel cpumask needs to issue a read barrier to match the write
83 * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
84 * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
85 * only performed at channel destruction.
87 #define for_each_channel_cpu(cpu, chan) \
88 for_each_possible_cpu(cpu)
90 extern struct lttng_ust_lib_ring_buffer
*channel_get_ring_buffer(
91 const struct lttng_ust_lib_ring_buffer_config
*config
,
92 struct channel
*chan
, int cpu
,
93 struct lttng_ust_shm_handle
*handle
,
94 int *shm_fd
, int *wait_fd
,
96 uint64_t *memory_map_size
);
98 int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config
*config
,
100 struct lttng_ust_shm_handle
*handle
);
102 int ring_buffer_channel_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config
*config
,
103 struct channel
*chan
,
104 struct lttng_ust_shm_handle
*handle
);
106 int ring_buffer_stream_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config
*config
,
107 struct channel
*chan
,
108 struct lttng_ust_shm_handle
*handle
,
111 int ring_buffer_stream_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config
*config
,
112 struct channel
*chan
,
113 struct lttng_ust_shm_handle
*handle
,
116 extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer
*buf
,
117 struct lttng_ust_shm_handle
*handle
);
118 extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer
*buf
,
119 struct lttng_ust_shm_handle
*handle
);
122 * Initialize signals for ring buffer. Should be called early e.g. by
123 * main() in the program to affect all threads.
125 void lib_ringbuffer_signal_init(void);
128 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
130 extern int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer
*buf
,
131 unsigned long *consumed
,
132 unsigned long *produced
,
133 struct lttng_ust_shm_handle
*handle
);
134 extern int lib_ring_buffer_snapshot_sample_positions(
135 struct lttng_ust_lib_ring_buffer
*buf
,
136 unsigned long *consumed
,
137 unsigned long *produced
,
138 struct lttng_ust_shm_handle
*handle
);
139 extern void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer
*buf
,
140 unsigned long consumed_new
,
141 struct lttng_ust_shm_handle
*handle
);
143 extern int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
144 unsigned long consumed
,
145 struct lttng_ust_shm_handle
*handle
);
146 extern void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
147 struct lttng_ust_shm_handle
*handle
);
150 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
151 * to read sub-buffers sequentially.
153 static inline int lib_ring_buffer_get_next_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
154 struct lttng_ust_shm_handle
*handle
)
158 ret
= lib_ring_buffer_snapshot(buf
, &buf
->cons_snapshot
,
159 &buf
->prod_snapshot
, handle
);
162 ret
= lib_ring_buffer_get_subbuf(buf
, buf
->cons_snapshot
, handle
);
167 void lib_ring_buffer_put_next_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
168 struct lttng_ust_shm_handle
*handle
)
170 struct channel
*chan
;
172 chan
= shmp(handle
, buf
->backend
.chan
);
175 lib_ring_buffer_put_subbuf(buf
, handle
);
176 lib_ring_buffer_move_consumer(buf
, subbuf_align(buf
->cons_snapshot
, chan
),
180 extern void channel_reset(struct channel
*chan
);
181 extern void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer
*buf
,
182 struct lttng_ust_shm_handle
*handle
);
185 unsigned long lib_ring_buffer_get_offset(const struct lttng_ust_lib_ring_buffer_config
*config
,
186 struct lttng_ust_lib_ring_buffer
*buf
)
188 return v_read(config
, &buf
->offset
);
192 unsigned long lib_ring_buffer_get_consumed(const struct lttng_ust_lib_ring_buffer_config
*config
,
193 struct lttng_ust_lib_ring_buffer
*buf
)
195 return uatomic_read(&buf
->consumed
);
199 * Must call lib_ring_buffer_is_finalized before reading counters (memory
200 * ordering enforced with respect to trace teardown).
203 int lib_ring_buffer_is_finalized(const struct lttng_ust_lib_ring_buffer_config
*config
,
204 struct lttng_ust_lib_ring_buffer
*buf
)
206 int finalized
= CMM_ACCESS_ONCE(buf
->finalized
);
208 * Read finalized before counters.
215 int lib_ring_buffer_channel_is_finalized(const struct channel
*chan
)
217 return chan
->finalized
;
221 int lib_ring_buffer_channel_is_disabled(const struct channel
*chan
)
223 return uatomic_read(&chan
->record_disabled
);
227 unsigned long lib_ring_buffer_get_read_data_size(
228 const struct lttng_ust_lib_ring_buffer_config
*config
,
229 struct lttng_ust_lib_ring_buffer
*buf
,
230 struct lttng_ust_shm_handle
*handle
)
232 return subbuffer_get_read_data_size(config
, &buf
->backend
, handle
);
236 unsigned long lib_ring_buffer_get_records_count(
237 const struct lttng_ust_lib_ring_buffer_config
*config
,
238 struct lttng_ust_lib_ring_buffer
*buf
)
240 return v_read(config
, &buf
->records_count
);
244 unsigned long lib_ring_buffer_get_records_overrun(
245 const struct lttng_ust_lib_ring_buffer_config
*config
,
246 struct lttng_ust_lib_ring_buffer
*buf
)
248 return v_read(config
, &buf
->records_overrun
);
252 unsigned long lib_ring_buffer_get_records_lost_full(
253 const struct lttng_ust_lib_ring_buffer_config
*config
,
254 struct lttng_ust_lib_ring_buffer
*buf
)
256 return v_read(config
, &buf
->records_lost_full
);
260 unsigned long lib_ring_buffer_get_records_lost_wrap(
261 const struct lttng_ust_lib_ring_buffer_config
*config
,
262 struct lttng_ust_lib_ring_buffer
*buf
)
264 return v_read(config
, &buf
->records_lost_wrap
);
268 unsigned long lib_ring_buffer_get_records_lost_big(
269 const struct lttng_ust_lib_ring_buffer_config
*config
,
270 struct lttng_ust_lib_ring_buffer
*buf
)
272 return v_read(config
, &buf
->records_lost_big
);
276 unsigned long lib_ring_buffer_get_records_read(
277 const struct lttng_ust_lib_ring_buffer_config
*config
,
278 struct lttng_ust_lib_ring_buffer
*buf
)
280 return v_read(config
, &buf
->backend
.records_read
);
283 #endif /* _LTTNG_RING_BUFFER_FRONTEND_H */