1 #ifndef _LINUX_RING_BUFFER_FRONTEND_H
2 #define _LINUX_RING_BUFFER_FRONTEND_H
5 * linux/ringbuffer/frontend.h
7 * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 * Ring Buffer Library Synchronization Header (API).
12 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
14 * See ring_buffer_frontend.c for more information on wait-free algorithms.
16 * Dual LGPL v2.1/GPL v2 license.
19 #include <urcu/compiler.h>
20 #include <urcu/uatomic.h>
23 /* Internal helpers */
24 #include "frontend_internal.h"
26 /* Buffer creation/removal and setup operations */
29 * switch_timer_interval is the time interval (in us) to fill sub-buffers with
30 * padding to let readers get those sub-buffers. Used for live streaming.
32 * read_timer_interval is the time interval (in us) to wake up pending readers.
34 * buf_addr is a pointer the the beginning of the preallocated buffer contiguous
35 * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
36 * be set to NULL for other backends.
40 struct shm_handle
*channel_create(const struct lib_ring_buffer_config
*config
,
41 const char *name
, void *priv
,
43 size_t subbuf_size
, size_t num_subbuf
,
44 unsigned int switch_timer_interval
,
45 unsigned int read_timer_interval
);
48 * channel_destroy returns the private data pointer. It finalizes all channel's
49 * buffers, waits for readers to release all references, and destroys the
53 void *channel_destroy(struct channel
*chan
, struct shm_handle
*handle
);
56 /* Buffer read operations */
59 * Iteration on channel cpumask needs to issue a read barrier to match the write
60 * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
61 * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
62 * only performed at channel destruction.
64 #define for_each_channel_cpu(cpu, chan) \
65 for_each_possible_cpu(cpu)
67 extern struct lib_ring_buffer
*channel_get_ring_buffer(
68 const struct lib_ring_buffer_config
*config
,
69 struct channel
*chan
, int cpu
,
70 struct shm_handle
*handle
,
71 int *shm_fd
, int *wait_fd
,
72 uint64_t *memory_map_size
);
73 extern int lib_ring_buffer_open_read(struct lib_ring_buffer
*buf
,
74 struct shm_handle
*handle
);
75 extern void lib_ring_buffer_release_read(struct lib_ring_buffer
*buf
,
76 struct shm_handle
*handle
);
79 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
81 extern int lib_ring_buffer_snapshot(struct lib_ring_buffer
*buf
,
82 unsigned long *consumed
,
83 unsigned long *produced
,
84 struct shm_handle
*handle
);
85 extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer
*buf
,
86 unsigned long consumed_new
,
87 struct shm_handle
*handle
);
89 extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer
*buf
,
90 unsigned long consumed
,
91 struct shm_handle
*handle
);
92 extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer
*buf
,
93 struct shm_handle
*handle
);
96 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
97 * to read sub-buffers sequentially.
99 static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer
*buf
,
100 struct shm_handle
*handle
)
104 ret
= lib_ring_buffer_snapshot(buf
, &buf
->cons_snapshot
,
105 &buf
->prod_snapshot
, handle
);
108 ret
= lib_ring_buffer_get_subbuf(buf
, buf
->cons_snapshot
, handle
);
113 void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer
*buf
,
114 struct shm_handle
*handle
)
116 lib_ring_buffer_put_subbuf(buf
, handle
);
117 lib_ring_buffer_move_consumer(buf
, subbuf_align(buf
->cons_snapshot
,
118 shmp(handle
, buf
->backend
.chan
)), handle
);
121 extern void channel_reset(struct channel
*chan
);
122 extern void lib_ring_buffer_reset(struct lib_ring_buffer
*buf
,
123 struct shm_handle
*handle
);
126 unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config
*config
,
127 struct lib_ring_buffer
*buf
)
129 return v_read(config
, &buf
->offset
);
133 unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config
*config
,
134 struct lib_ring_buffer
*buf
)
136 return uatomic_read(&buf
->consumed
);
140 * Must call lib_ring_buffer_is_finalized before reading counters (memory
141 * ordering enforced with respect to trace teardown).
144 int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config
*config
,
145 struct lib_ring_buffer
*buf
)
147 int finalized
= CMM_ACCESS_ONCE(buf
->finalized
);
149 * Read finalized before counters.
156 int lib_ring_buffer_channel_is_finalized(const struct channel
*chan
)
158 return chan
->finalized
;
162 int lib_ring_buffer_channel_is_disabled(const struct channel
*chan
)
164 return uatomic_read(&chan
->record_disabled
);
168 unsigned long lib_ring_buffer_get_read_data_size(
169 const struct lib_ring_buffer_config
*config
,
170 struct lib_ring_buffer
*buf
,
171 struct shm_handle
*handle
)
173 return subbuffer_get_read_data_size(config
, &buf
->backend
, handle
);
177 unsigned long lib_ring_buffer_get_records_count(
178 const struct lib_ring_buffer_config
*config
,
179 struct lib_ring_buffer
*buf
)
181 return v_read(config
, &buf
->records_count
);
185 unsigned long lib_ring_buffer_get_records_overrun(
186 const struct lib_ring_buffer_config
*config
,
187 struct lib_ring_buffer
*buf
)
189 return v_read(config
, &buf
->records_overrun
);
193 unsigned long lib_ring_buffer_get_records_lost_full(
194 const struct lib_ring_buffer_config
*config
,
195 struct lib_ring_buffer
*buf
)
197 return v_read(config
, &buf
->records_lost_full
);
201 unsigned long lib_ring_buffer_get_records_lost_wrap(
202 const struct lib_ring_buffer_config
*config
,
203 struct lib_ring_buffer
*buf
)
205 return v_read(config
, &buf
->records_lost_wrap
);
209 unsigned long lib_ring_buffer_get_records_lost_big(
210 const struct lib_ring_buffer_config
*config
,
211 struct lib_ring_buffer
*buf
)
213 return v_read(config
, &buf
->records_lost_big
);
217 unsigned long lib_ring_buffer_get_records_read(
218 const struct lib_ring_buffer_config
*config
,
219 struct lib_ring_buffer
*buf
)
221 return v_read(config
, &buf
->backend
.records_read
);
224 #endif /* _LINUX_RING_BUFFER_FRONTEND_H */
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