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
);
70 * channel_destroy finalizes all channel's buffers, waits for readers to
71 * release all references, and destroys the channel.
74 void channel_destroy(struct channel
*chan
, struct lttng_ust_shm_handle
*handle
,
78 /* Buffer read operations */
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.
86 #define for_each_channel_cpu(cpu, chan) \
87 for_each_possible_cpu(cpu)
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
,
95 uint64_t *memory_map_size
);
97 int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config
*config
,
99 struct lttng_ust_shm_handle
*handle
);
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
);
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
,
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
,
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
);
121 * Initialize signals for ring buffer. Should be called early e.g. by
122 * main() in the program to affect all threads.
124 void lib_ringbuffer_signal_init(void);
127 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
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
);
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
);
144 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
145 * to read sub-buffers sequentially.
147 static inline int lib_ring_buffer_get_next_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
148 struct lttng_ust_shm_handle
*handle
)
152 ret
= lib_ring_buffer_snapshot(buf
, &buf
->cons_snapshot
,
153 &buf
->prod_snapshot
, handle
);
156 ret
= lib_ring_buffer_get_subbuf(buf
, buf
->cons_snapshot
, handle
);
161 void lib_ring_buffer_put_next_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
162 struct lttng_ust_shm_handle
*handle
)
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
);
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
);
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
)
177 return v_read(config
, &buf
->offset
);
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
)
184 return uatomic_read(&buf
->consumed
);
188 * Must call lib_ring_buffer_is_finalized before reading counters (memory
189 * ordering enforced with respect to trace teardown).
192 int lib_ring_buffer_is_finalized(const struct lttng_ust_lib_ring_buffer_config
*config
,
193 struct lttng_ust_lib_ring_buffer
*buf
)
195 int finalized
= CMM_ACCESS_ONCE(buf
->finalized
);
197 * Read finalized before counters.
204 int lib_ring_buffer_channel_is_finalized(const struct channel
*chan
)
206 return chan
->finalized
;
210 int lib_ring_buffer_channel_is_disabled(const struct channel
*chan
)
212 return uatomic_read(&chan
->record_disabled
);
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
)
221 return subbuffer_get_read_data_size(config
, &buf
->backend
, handle
);
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
)
229 return v_read(config
, &buf
->records_count
);
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
)
237 return v_read(config
, &buf
->records_overrun
);
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
)
245 return v_read(config
, &buf
->records_lost_full
);
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
)
253 return v_read(config
, &buf
->records_lost_wrap
);
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
)
261 return v_read(config
, &buf
->records_lost_big
);
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
)
269 return v_read(config
, &buf
->backend
.records_read
);
272 #endif /* _LTTNG_RING_BUFFER_FRONTEND_H */