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 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 extern int lib_ring_buffer_open_read(struct lib_ring_buffer
*buf
);
71 extern void lib_ring_buffer_release_read(struct lib_ring_buffer
*buf
);
74 * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
76 extern int lib_ring_buffer_snapshot(struct lib_ring_buffer
*buf
,
77 unsigned long *consumed
,
78 unsigned long *produced
);
79 extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer
*buf
,
80 unsigned long consumed_new
);
82 extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer
*buf
,
83 unsigned long consumed
);
84 extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer
*buf
);
87 * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
88 * to read sub-buffers sequentially.
90 static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer
*buf
)
94 ret
= lib_ring_buffer_snapshot(buf
, &buf
->cons_snapshot
,
98 ret
= lib_ring_buffer_get_subbuf(buf
, buf
->cons_snapshot
);
102 static inline void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer
*buf
)
104 lib_ring_buffer_put_subbuf(buf
);
105 lib_ring_buffer_move_consumer(buf
, subbuf_align(buf
->cons_snapshot
,
106 shmp(buf
->backend
.chan
)));
109 extern void channel_reset(struct channel
*chan
);
110 extern void lib_ring_buffer_reset(struct lib_ring_buffer
*buf
);
113 unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config
*config
,
114 struct lib_ring_buffer
*buf
)
116 return v_read(config
, &buf
->offset
);
120 unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config
*config
,
121 struct lib_ring_buffer
*buf
)
123 return uatomic_read(&buf
->consumed
);
127 * Must call lib_ring_buffer_is_finalized before reading counters (memory
128 * ordering enforced with respect to trace teardown).
131 int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config
*config
,
132 struct lib_ring_buffer
*buf
)
134 int finalized
= CMM_ACCESS_ONCE(buf
->finalized
);
136 * Read finalized before counters.
143 int lib_ring_buffer_channel_is_finalized(const struct channel
*chan
)
145 return chan
->finalized
;
149 int lib_ring_buffer_channel_is_disabled(const struct channel
*chan
)
151 return uatomic_read(&chan
->record_disabled
);
155 unsigned long lib_ring_buffer_get_read_data_size(
156 const struct lib_ring_buffer_config
*config
,
157 struct lib_ring_buffer
*buf
)
159 return subbuffer_get_read_data_size(config
, &buf
->backend
);
163 unsigned long lib_ring_buffer_get_records_count(
164 const struct lib_ring_buffer_config
*config
,
165 struct lib_ring_buffer
*buf
)
167 return v_read(config
, &buf
->records_count
);
171 unsigned long lib_ring_buffer_get_records_overrun(
172 const struct lib_ring_buffer_config
*config
,
173 struct lib_ring_buffer
*buf
)
175 return v_read(config
, &buf
->records_overrun
);
179 unsigned long lib_ring_buffer_get_records_lost_full(
180 const struct lib_ring_buffer_config
*config
,
181 struct lib_ring_buffer
*buf
)
183 return v_read(config
, &buf
->records_lost_full
);
187 unsigned long lib_ring_buffer_get_records_lost_wrap(
188 const struct lib_ring_buffer_config
*config
,
189 struct lib_ring_buffer
*buf
)
191 return v_read(config
, &buf
->records_lost_wrap
);
195 unsigned long lib_ring_buffer_get_records_lost_big(
196 const struct lib_ring_buffer_config
*config
,
197 struct lib_ring_buffer
*buf
)
199 return v_read(config
, &buf
->records_lost_big
);
203 unsigned long lib_ring_buffer_get_records_read(
204 const struct lib_ring_buffer_config
*config
,
205 struct lib_ring_buffer
*buf
)
207 return v_read(config
, &buf
->backend
.records_read
);
210 #endif /* _LINUX_RING_BUFFER_FRONTEND_H */
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