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_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config
*config
,
99 struct lttng_ust_shm_handle
*handle
,
102 int ring_buffer_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config
*config
,
103 struct channel
*chan
,
104 struct lttng_ust_shm_handle
*handle
,
107 extern int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer
*buf
,
108 struct lttng_ust_shm_handle
*handle
);
109 extern void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer
*buf
,
110 struct lttng_ust_shm_handle
*handle
);
113 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
115 extern int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer
*buf
,
116 unsigned long *consumed
,
117 unsigned long *produced
,
118 struct lttng_ust_shm_handle
*handle
);
119 extern void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer
*buf
,
120 unsigned long consumed_new
,
121 struct lttng_ust_shm_handle
*handle
);
123 extern int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
124 unsigned long consumed
,
125 struct lttng_ust_shm_handle
*handle
);
126 extern void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
127 struct lttng_ust_shm_handle
*handle
);
130 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
131 * to read sub-buffers sequentially.
133 static inline int lib_ring_buffer_get_next_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
134 struct lttng_ust_shm_handle
*handle
)
138 ret
= lib_ring_buffer_snapshot(buf
, &buf
->cons_snapshot
,
139 &buf
->prod_snapshot
, handle
);
142 ret
= lib_ring_buffer_get_subbuf(buf
, buf
->cons_snapshot
, handle
);
147 void lib_ring_buffer_put_next_subbuf(struct lttng_ust_lib_ring_buffer
*buf
,
148 struct lttng_ust_shm_handle
*handle
)
150 lib_ring_buffer_put_subbuf(buf
, handle
);
151 lib_ring_buffer_move_consumer(buf
, subbuf_align(buf
->cons_snapshot
,
152 shmp(handle
, buf
->backend
.chan
)), handle
);
155 extern void channel_reset(struct channel
*chan
);
156 extern void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer
*buf
,
157 struct lttng_ust_shm_handle
*handle
);
160 unsigned long lib_ring_buffer_get_offset(const struct lttng_ust_lib_ring_buffer_config
*config
,
161 struct lttng_ust_lib_ring_buffer
*buf
)
163 return v_read(config
, &buf
->offset
);
167 unsigned long lib_ring_buffer_get_consumed(const struct lttng_ust_lib_ring_buffer_config
*config
,
168 struct lttng_ust_lib_ring_buffer
*buf
)
170 return uatomic_read(&buf
->consumed
);
174 * Must call lib_ring_buffer_is_finalized before reading counters (memory
175 * ordering enforced with respect to trace teardown).
178 int lib_ring_buffer_is_finalized(const struct lttng_ust_lib_ring_buffer_config
*config
,
179 struct lttng_ust_lib_ring_buffer
*buf
)
181 int finalized
= CMM_ACCESS_ONCE(buf
->finalized
);
183 * Read finalized before counters.
190 int lib_ring_buffer_channel_is_finalized(const struct channel
*chan
)
192 return chan
->finalized
;
196 int lib_ring_buffer_channel_is_disabled(const struct channel
*chan
)
198 return uatomic_read(&chan
->record_disabled
);
202 unsigned long lib_ring_buffer_get_read_data_size(
203 const struct lttng_ust_lib_ring_buffer_config
*config
,
204 struct lttng_ust_lib_ring_buffer
*buf
,
205 struct lttng_ust_shm_handle
*handle
)
207 return subbuffer_get_read_data_size(config
, &buf
->backend
, handle
);
211 unsigned long lib_ring_buffer_get_records_count(
212 const struct lttng_ust_lib_ring_buffer_config
*config
,
213 struct lttng_ust_lib_ring_buffer
*buf
)
215 return v_read(config
, &buf
->records_count
);
219 unsigned long lib_ring_buffer_get_records_overrun(
220 const struct lttng_ust_lib_ring_buffer_config
*config
,
221 struct lttng_ust_lib_ring_buffer
*buf
)
223 return v_read(config
, &buf
->records_overrun
);
227 unsigned long lib_ring_buffer_get_records_lost_full(
228 const struct lttng_ust_lib_ring_buffer_config
*config
,
229 struct lttng_ust_lib_ring_buffer
*buf
)
231 return v_read(config
, &buf
->records_lost_full
);
235 unsigned long lib_ring_buffer_get_records_lost_wrap(
236 const struct lttng_ust_lib_ring_buffer_config
*config
,
237 struct lttng_ust_lib_ring_buffer
*buf
)
239 return v_read(config
, &buf
->records_lost_wrap
);
243 unsigned long lib_ring_buffer_get_records_lost_big(
244 const struct lttng_ust_lib_ring_buffer_config
*config
,
245 struct lttng_ust_lib_ring_buffer
*buf
)
247 return v_read(config
, &buf
->records_lost_big
);
251 unsigned long lib_ring_buffer_get_records_read(
252 const struct lttng_ust_lib_ring_buffer_config
*config
,
253 struct lttng_ust_lib_ring_buffer
*buf
)
255 return v_read(config
, &buf
->backend
.records_read
);
258 #endif /* _LTTNG_RING_BUFFER_FRONTEND_H */