src/common/ust-consumer/ust-consumer.c

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <assert.h>
  21 #include <poll.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/mman.h>
  26 #include <sys/socket.h>
  27 #include <sys/stat.h>
  28 #include <sys/types.h>
  29 #include <unistd.h>
  30 #include <lttng/ust-ctl.h>
  31
  32 #include <common/common.h>
  33 #include <common/sessiond-comm/sessiond-comm.h>
  34 #include <common/compat/fcntl.h>
  35
  36 #include "ust-consumer.h"
  37
  38 extern struct lttng_consumer_global_data consumer_data;
  39 extern int consumer_poll_timeout;
  40 extern volatile int consumer_quit;
  41
  42 /*
  43  * Mmap the ring buffer, read it and write the data to the tracefile.
  44  *
  45  * Returns the number of bytes written, else negative value on error.
  46  */
  47 ssize_t lttng_ustconsumer_on_read_subbuffer_mmap(
  48                 struct lttng_consumer_local_data *ctx,
  49                 struct lttng_consumer_stream *stream, unsigned long len)
  50 {
  51         unsigned long mmap_offset;
  52         long ret = 0;
  53         off_t orig_offset = stream->out_fd_offset;
  54         int outfd = stream->out_fd;
  55
  56         /* get the offset inside the fd to mmap */
  57         ret = ustctl_get_mmap_read_offset(stream->chan->handle,
  58                 stream->buf, &mmap_offset);
  59         if (ret != 0) {
  60                 errno = -ret;
  61                 PERROR("ustctl_get_mmap_read_offset");
  62                 goto end;
  63         }
  64         while (len > 0) {
  65                 ret = write(outfd, stream->mmap_base + mmap_offset, len);
  66                 if (ret >= len) {
  67                         len = 0;
  68                 } else if (ret < 0) {
  69                         errno = -ret;
  70                         PERROR("Error in file write");
  71                         goto end;
  72                 }
  73                 /* This won't block, but will start writeout asynchronously */
  74                 lttng_sync_file_range(outfd, stream->out_fd_offset, ret,
  75                                 SYNC_FILE_RANGE_WRITE);
  76                 stream->out_fd_offset += ret;
  77         }
  78
  79         lttng_consumer_sync_trace_file(stream, orig_offset);
  80
  81         goto end;
  82
  83 end:
  84         return ret;
  85 }
  86
  87 /*
  88  * Splice the data from the ring buffer to the tracefile.
  89  *
  90  * Returns the number of bytes spliced.
  91  */
  92 ssize_t lttng_ustconsumer_on_read_subbuffer_splice(
  93                 struct lttng_consumer_local_data *ctx,
  94                 struct lttng_consumer_stream *stream, unsigned long len)
  95 {
  96         return -ENOSYS;
  97 }
  98
  99 /*
 100  * Take a snapshot for a specific fd
 101  *
 102  * Returns 0 on success, < 0 on error
 103  */
 104 int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 105                 struct lttng_consumer_stream *stream)
 106 {
 107         int ret = 0;
 108
 109         ret = ustctl_snapshot(stream->chan->handle, stream->buf);
 110         if (ret != 0) {
 111                 errno = -ret;
 112                 PERROR("Getting sub-buffer snapshot.");
 113         }
 114
 115         return ret;
 116 }
 117
 118 /*
 119  * Get the produced position
 120  *
 121  * Returns 0 on success, < 0 on error
 122  */
 123 int lttng_ustconsumer_get_produced_snapshot(
 124                 struct lttng_consumer_local_data *ctx,
 125                 struct lttng_consumer_stream *stream,
 126                 unsigned long *pos)
 127 {
 128         int ret;
 129
 130         ret = ustctl_snapshot_get_produced(stream->chan->handle,
 131                         stream->buf, pos);
 132         if (ret != 0) {
 133                 errno = -ret;
 134                 PERROR("kernctl_snapshot_get_produced");
 135         }
 136
 137         return ret;
 138 }
 139
 140 int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 141                 int sock, struct pollfd *consumer_sockpoll)
 142 {
 143         ssize_t ret;
 144         struct lttcomm_consumer_msg msg;
 145
 146         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 147         if (ret != sizeof(msg)) {
 148                 lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 149                 return ret;
 150         }
 151         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 152                 return -ENOENT;
 153         }
 154
 155         switch (msg.cmd_type) {
 156         case LTTNG_CONSUMER_ADD_CHANNEL:
 157         {
 158                 struct lttng_consumer_channel *new_channel;
 159                 int fds[1];
 160                 size_t nb_fd = 1;
 161
 162                 /* block */
 163                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 164                         return -EINTR;
 165                 }
 166                 ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
 167                 if (ret != sizeof(fds)) {
 168                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 169                         return ret;
 170                 }
 171
 172                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 173
 174                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 175                                 fds[0], -1,
 176                                 msg.u.channel.mmap_len,
 177                                 msg.u.channel.max_sb_size);
 178                 if (new_channel == NULL) {
 179                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 180                         goto end_nosignal;
 181                 }
 182                 if (ctx->on_recv_channel != NULL) {
 183                         ret = ctx->on_recv_channel(new_channel);
 184                         if (ret == 0) {
 185                                 consumer_add_channel(new_channel);
 186                         } else if (ret < 0) {
 187                                 goto end_nosignal;
 188                         }
 189                 } else {
 190                         consumer_add_channel(new_channel);
 191                 }
 192                 goto end_nosignal;
 193         }
 194         case LTTNG_CONSUMER_ADD_STREAM:
 195         {
 196                 struct lttng_consumer_stream *new_stream;
 197                 int fds[2];
 198                 size_t nb_fd = 2;
 199
 200                 /* block */
 201                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 202                         return -EINTR;
 203                 }
 204                 ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
 205                 if (ret != sizeof(fds)) {
 206                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 207                         return ret;
 208                 }
 209
 210                 DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
 211                         fds[0], fds[1]);
 212                 assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
 213                 new_stream = consumer_allocate_stream(msg.u.channel.channel_key,
 214                                 msg.u.stream.stream_key,
 215                                 fds[0], fds[1],
 216                                 msg.u.stream.state,
 217                                 msg.u.stream.mmap_len,
 218                                 msg.u.stream.output,
 219                                 msg.u.stream.path_name,
 220                                 msg.u.stream.uid,
 221                                 msg.u.stream.gid);
 222                 if (new_stream == NULL) {
 223                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 224                         goto end;
 225                 }
 226                 if (ctx->on_recv_stream != NULL) {
 227                         ret = ctx->on_recv_stream(new_stream);
 228                         if (ret == 0) {
 229                                 consumer_add_stream(new_stream);
 230                         } else if (ret < 0) {
 231                                 goto end;
 232                         }
 233                 } else {
 234                         consumer_add_stream(new_stream);
 235                 }
 236                 break;
 237         }
 238         case LTTNG_CONSUMER_UPDATE_STREAM:
 239         {
 240                 return -ENOSYS;
 241 #if 0
 242                 if (ctx->on_update_stream != NULL) {
 243                         ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
 244                         if (ret == 0) {
 245                                 consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
 246                         } else if (ret < 0) {
 247                                 goto end;
 248                         }
 249                 } else {
 250                         consumer_change_stream_state(msg.u.stream.stream_key,
 251                                 msg.u.stream.state);
 252                 }
 253 #endif
 254                 break;
 255         }
 256         default:
 257                 break;
 258         }
 259 end:
 260         /*
 261          * Wake-up the other end by writing a null byte in the pipe
 262          * (non-blocking). Important note: Because writing into the
 263          * pipe is non-blocking (and therefore we allow dropping wakeup
 264          * data, as long as there is wakeup data present in the pipe
 265          * buffer to wake up the other end), the other end should
 266          * perform the following sequence for waiting:
 267          * 1) empty the pipe (reads).
 268          * 2) perform update operation.
 269          * 3) wait on the pipe (poll).
 270          */
 271         do {
 272                 ret = write(ctx->consumer_poll_pipe[1], "", 1);
 273         } while (ret == -1UL && errno == EINTR);
 274 end_nosignal:
 275         return 0;
 276 }
 277
 278 int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
 279 {
 280         struct lttng_ust_object_data obj;
 281
 282         obj.handle = -1;
 283         obj.shm_fd = chan->shm_fd;
 284         obj.wait_fd = chan->wait_fd;
 285         obj.memory_map_size = chan->mmap_len;
 286         chan->handle = ustctl_map_channel(&obj);
 287         if (!chan->handle) {
 288                 return -ENOMEM;
 289         }
 290         chan->wait_fd_is_copy = 1;
 291         chan->shm_fd = -1;
 292
 293         return 0;
 294 }
 295
 296 void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
 297 {
 298         ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
 299         stream->hangup_flush_done = 1;
 300 }
 301
 302 void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
 303 {
 304         ustctl_unmap_channel(chan->handle);
 305 }
 306
 307 int lttng_ustconsumer_allocate_stream(struct lttng_consumer_stream *stream)
 308 {
 309         struct lttng_ust_object_data obj;
 310         int ret;
 311
 312         obj.handle = -1;
 313         obj.shm_fd = stream->shm_fd;
 314         obj.wait_fd = stream->wait_fd;
 315         obj.memory_map_size = stream->mmap_len;
 316         ret = ustctl_add_stream(stream->chan->handle, &obj);
 317         if (ret)
 318                 return ret;
 319         stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
 320         if (!stream->buf)
 321                 return -EBUSY;
 322         /* ustctl_open_stream_read has closed the shm fd. */
 323         stream->wait_fd_is_copy = 1;
 324         stream->shm_fd = -1;
 325
 326         stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
 327         if (!stream->mmap_base) {
 328                 return -EINVAL;
 329         }
 330
 331         return 0;
 332 }
 333
 334 void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
 335 {
 336         ustctl_close_stream_read(stream->chan->handle, stream->buf);
 337 }
 338
 339
 340 int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 341                 struct lttng_consumer_local_data *ctx)
 342 {
 343         unsigned long len;
 344         int err;
 345         long ret = 0;
 346         struct lttng_ust_shm_handle *handle;
 347         struct lttng_ust_lib_ring_buffer *buf;
 348         char dummy;
 349         ssize_t readlen;
 350
 351         DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
 352                 stream->wait_fd, stream->key);
 353
 354         /* We can consume the 1 byte written into the wait_fd by UST */
 355         if (!stream->hangup_flush_done) {
 356                 do {
 357                         readlen = read(stream->wait_fd, &dummy, 1);
 358                 } while (readlen == -1 && errno == EINTR);
 359                 if (readlen == -1) {
 360                         ret = readlen;
 361                         goto end;
 362                 }
 363         }
 364
 365         buf = stream->buf;
 366         handle = stream->chan->handle;
 367         /* Get the next subbuffer */
 368         err = ustctl_get_next_subbuf(handle, buf);
 369         if (err != 0) {
 370                 ret = -ret;     /* ustctl_get_next_subbuf returns negative, caller expect positive. */
 371                 /*
 372                  * This is a debug message even for single-threaded consumer,
 373                  * because poll() have more relaxed criterions than get subbuf,
 374                  * so get_subbuf may fail for short race windows where poll()
 375                  * would issue wakeups.
 376                  */
 377                 DBG("Reserving sub buffer failed (everything is normal, "
 378                                 "it is due to concurrency)");
 379                 goto end;
 380         }
 381         assert(stream->output == LTTNG_EVENT_MMAP);
 382         /* read the used subbuffer size */
 383         err = ustctl_get_padded_subbuf_size(handle, buf, &len);
 384         assert(err == 0);
 385         /* write the subbuffer to the tracefile */
 386         ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
 387         if (ret < 0) {
 388                 /*
 389                  * display the error but continue processing to try
 390                  * to release the subbuffer
 391                  */
 392                 ERR("Error writing to tracefile");
 393         }
 394         err = ustctl_put_next_subbuf(handle, buf);
 395         assert(err == 0);
 396 end:
 397         return ret;
 398 }
 399
 400 int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 401 {
 402         int ret;
 403
 404         /* Opening the tracefile in write mode */
 405         if (stream->path_name != NULL) {
 406                 ret = run_as_open(stream->path_name,
 407                                 O_WRONLY|O_CREAT|O_TRUNC,
 408                                 S_IRWXU|S_IRWXG|S_IRWXO,
 409                                 stream->uid, stream->gid);
 410                 if (ret < 0) {
 411                         ERR("Opening %s", stream->path_name);
 412                         PERROR("open");
 413                         goto error;
 414                 }
 415                 stream->out_fd = ret;
 416         }
 417
 418         /* we return 0 to let the library handle the FD internally */
 419         return 0;
 420
 421 error:
 422         return ret;
 423 }