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