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Move libcounter to 'src/common/'
[lttng-ust.git] / src / libringbuffer / frontend.h
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1/*
2 * SPDX-License-Identifier: LGPL-2.1-only
3 *
4 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
5 *
6 * Ring Buffer Library Synchronization Header (API).
7 *
8 * See ring_buffer_frontend.c for more information on wait-free algorithms.
9 */
10
11#ifndef _LTTNG_RING_BUFFER_FRONTEND_H
12#define _LTTNG_RING_BUFFER_FRONTEND_H
13
14#include <stddef.h>
15#include <stdint.h>
16
17#include <urcu/compiler.h>
18#include <urcu/uatomic.h>
19
20#include "smp.h"
21
22/* Internal helpers */
23#include "frontend_internal.h"
24
25/* Buffer creation/removal and setup operations */
26
27/*
28 * switch_timer_interval is the time interval (in us) to fill sub-buffers with
29 * padding to let readers get those sub-buffers. Used for live streaming.
30 *
31 * read_timer_interval is the time interval (in us) to wake up pending readers.
32 *
33 * buf_addr is a pointer the the beginning of the preallocated buffer contiguous
34 * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
35 * be set to NULL for other backends.
36 *
37 * private data is a memory area for configuration data. This memory is
38 * managed by lib ring buffer. priv_data_align is the alignment required
39 * for the private data area.
40 */
41
42extern
43struct lttng_ust_shm_handle *channel_create(const struct lttng_ust_lib_ring_buffer_config *config,
44 const char *name,
45 size_t priv_data_align,
46 size_t priv_data_size,
47 void *priv_data_init,
48 void *priv,
49 void *buf_addr,
50 size_t subbuf_size, size_t num_subbuf,
51 unsigned int switch_timer_interval,
52 unsigned int read_timer_interval,
53 const int *stream_fds, int nr_stream_fds,
54 int64_t blocking_timeout)
55 __attribute__((visibility("hidden")));
56
57/*
58 * channel_destroy finalizes all channel's buffers, waits for readers to
59 * release all references, and destroys the channel.
60 */
61void channel_destroy(struct lttng_ust_lib_ring_buffer_channel *chan,
62 struct lttng_ust_shm_handle *handle,
63 int consumer)
64 __attribute__((visibility("hidden")));
65
66
67/* Buffer read operations */
68
69/*
70 * Iteration on channel cpumask needs to issue a read barrier to match the write
71 * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
72 * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
73 * only performed at channel destruction.
74 */
75#define for_each_channel_cpu(cpu, chan) \
76 for_each_possible_cpu(cpu)
77
78extern struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer(
79 const struct lttng_ust_lib_ring_buffer_config *config,
80 struct lttng_ust_lib_ring_buffer_channel *chan, int cpu,
81 struct lttng_ust_shm_handle *handle,
82 int *shm_fd, int *wait_fd,
83 int *wakeup_fd,
84 uint64_t *memory_map_size)
85 __attribute__((visibility("hidden")));
86
87extern
88int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
89 struct lttng_ust_lib_ring_buffer_channel *chan,
90 struct lttng_ust_shm_handle *handle)
91 __attribute__((visibility("hidden")));
92
93extern
94int ring_buffer_channel_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
95 struct lttng_ust_lib_ring_buffer_channel *chan,
96 struct lttng_ust_shm_handle *handle)
97 __attribute__((visibility("hidden")));
98
99extern
100int ring_buffer_stream_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config,
101 struct lttng_ust_lib_ring_buffer_channel *chan,
102 struct lttng_ust_shm_handle *handle,
103 int cpu)
104 __attribute__((visibility("hidden")));
105
106extern
107int ring_buffer_stream_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config,
108 struct lttng_ust_lib_ring_buffer_channel *chan,
109 struct lttng_ust_shm_handle *handle,
110 int cpu)
111 __attribute__((visibility("hidden")));
112
113extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,
114 struct lttng_ust_shm_handle *handle)
115 __attribute__((visibility("hidden")));
116
117extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf,
118 struct lttng_ust_shm_handle *handle)
119 __attribute__((visibility("hidden")));
120
121/*
122 * Initialize signals for ring buffer. Should be called early e.g. by
123 * main() in the program to affect all threads.
124 */
125void lib_ringbuffer_signal_init(void)
126 __attribute__((visibility("hidden")));
127
128/*
129 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
130 */
131extern int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer *buf,
132 unsigned long *consumed,
133 unsigned long *produced,
134 struct lttng_ust_shm_handle *handle)
135 __attribute__((visibility("hidden")));
136
137extern int lib_ring_buffer_snapshot_sample_positions(
138 struct lttng_ust_lib_ring_buffer *buf,
139 unsigned long *consumed,
140 unsigned long *produced,
141 struct lttng_ust_shm_handle *handle)
142 __attribute__((visibility("hidden")));
143
144extern void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer *buf,
145 unsigned long consumed_new,
146 struct lttng_ust_shm_handle *handle)
147 __attribute__((visibility("hidden")));
148
149extern int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf,
150 unsigned long consumed,
151 struct lttng_ust_shm_handle *handle)
152 __attribute__((visibility("hidden")));
153
154extern void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf,
155 struct lttng_ust_shm_handle *handle)
156 __attribute__((visibility("hidden")));
157
158/*
159 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
160 * to read sub-buffers sequentially.
161 */
162static inline int lib_ring_buffer_get_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
163 struct lttng_ust_shm_handle *handle)
164{
165 int ret;
166
167 ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
168 &buf->prod_snapshot, handle);
169 if (ret)
170 return ret;
171 ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot, handle);
172 return ret;
173}
174
175static inline
176void lib_ring_buffer_put_next_subbuf(struct lttng_ust_lib_ring_buffer *buf,
177 struct lttng_ust_shm_handle *handle)
178{
179 struct lttng_ust_lib_ring_buffer_channel *chan;
180
181 chan = shmp(handle, buf->backend.chan);
182 if (!chan)
183 return;
184 lib_ring_buffer_put_subbuf(buf, handle);
185 lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot, chan),
186 handle);
187}
188
189extern void channel_reset(struct lttng_ust_lib_ring_buffer_channel *chan)
190 __attribute__((visibility("hidden")));
191
192extern void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf,
193 struct lttng_ust_shm_handle *handle)
194 __attribute__((visibility("hidden")));
195
196static inline
197unsigned long lib_ring_buffer_get_offset(const struct lttng_ust_lib_ring_buffer_config *config,
198 struct lttng_ust_lib_ring_buffer *buf)
199{
200 return v_read(config, &buf->offset);
201}
202
203static inline
204unsigned long lib_ring_buffer_get_consumed(
205 const struct lttng_ust_lib_ring_buffer_config *config __attribute__((unused)),
206 struct lttng_ust_lib_ring_buffer *buf)
207{
208 return uatomic_read(&buf->consumed);
209}
210
211/*
212 * Must call lib_ring_buffer_is_finalized before reading counters (memory
213 * ordering enforced with respect to trace teardown).
214 */
215static inline
216int lib_ring_buffer_is_finalized(
217 const struct lttng_ust_lib_ring_buffer_config *config __attribute__((unused)),
218 struct lttng_ust_lib_ring_buffer *buf)
219{
220 int finalized = CMM_ACCESS_ONCE(buf->finalized);
221 /*
222 * Read finalized before counters.
223 */
224 cmm_smp_rmb();
225 return finalized;
226}
227
228static inline
229int lib_ring_buffer_channel_is_finalized(const struct lttng_ust_lib_ring_buffer_channel *chan)
230{
231 return chan->finalized;
232}
233
234static inline
235int lib_ring_buffer_channel_is_disabled(const struct lttng_ust_lib_ring_buffer_channel *chan)
236{
237 return uatomic_read(&chan->record_disabled);
238}
239
240static inline
241unsigned long lib_ring_buffer_get_read_data_size(
242 const struct lttng_ust_lib_ring_buffer_config *config,
243 struct lttng_ust_lib_ring_buffer *buf,
244 struct lttng_ust_shm_handle *handle)
245{
246 return subbuffer_get_read_data_size(config, &buf->backend, handle);
247}
248
249static inline
250unsigned long lib_ring_buffer_get_records_count(
251 const struct lttng_ust_lib_ring_buffer_config *config,
252 struct lttng_ust_lib_ring_buffer *buf)
253{
254 return v_read(config, &buf->records_count);
255}
256
257static inline
258unsigned long lib_ring_buffer_get_records_overrun(
259 const struct lttng_ust_lib_ring_buffer_config *config,
260 struct lttng_ust_lib_ring_buffer *buf)
261{
262 return v_read(config, &buf->records_overrun);
263}
264
265static inline
266unsigned long lib_ring_buffer_get_records_lost_full(
267 const struct lttng_ust_lib_ring_buffer_config *config,
268 struct lttng_ust_lib_ring_buffer *buf)
269{
270 return v_read(config, &buf->records_lost_full);
271}
272
273static inline
274unsigned long lib_ring_buffer_get_records_lost_wrap(
275 const struct lttng_ust_lib_ring_buffer_config *config,
276 struct lttng_ust_lib_ring_buffer *buf)
277{
278 return v_read(config, &buf->records_lost_wrap);
279}
280
281static inline
282unsigned long lib_ring_buffer_get_records_lost_big(
283 const struct lttng_ust_lib_ring_buffer_config *config,
284 struct lttng_ust_lib_ring_buffer *buf)
285{
286 return v_read(config, &buf->records_lost_big);
287}
288
289static inline
290unsigned long lib_ring_buffer_get_records_read(
291 const struct lttng_ust_lib_ring_buffer_config *config,
292 struct lttng_ust_lib_ring_buffer *buf)
293{
294 return v_read(config, &buf->backend.records_read);
295}
296
297#endif /* _LTTNG_RING_BUFFER_FRONTEND_H */
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