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, written = 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                 written = ret;
  63                 goto end;
  64         }
  65         while (len > 0) {
  66                 ret = write(outfd, stream->mmap_base + mmap_offset, len);
  67                 if (ret < 0) {
  68                         if (errno == EINTR) {
  69                                 /* restart the interrupted system call */
  70                                 continue;
  71                         } else {
  72                                 PERROR("Error in file write");
  73                                 if (written == 0) {
  74                                         written = ret;
  75                                 }
  76                                 goto end;
  77                         }
  78                 } else if (ret > len) {
  79                         PERROR("Error in file write");
  80                         written += ret;
  81                         goto end;
  82                 } else {
  83                         len -= ret;
  84                         mmap_offset += ret;
  85                 }
  86                 /* This won't block, but will start writeout asynchronously */
  87                 lttng_sync_file_range(outfd, stream->out_fd_offset, ret,
  88                                 SYNC_FILE_RANGE_WRITE);
  89                 stream->out_fd_offset += ret;
  90                 written += ret;
  91         }
  92         lttng_consumer_sync_trace_file(stream, orig_offset);
  93 end:
  94         return written;
  95 }
  96
  97 /*
  98  * Splice the data from the ring buffer to the tracefile.
  99  *
 100  * Returns the number of bytes spliced.
 101  */
 102 ssize_t lttng_ustconsumer_on_read_subbuffer_splice(
 103                 struct lttng_consumer_local_data *ctx,
 104                 struct lttng_consumer_stream *stream, unsigned long len)
 105 {
 106         return -ENOSYS;
 107 }
 108
 109 /*
 110  * Take a snapshot for a specific fd
 111  *
 112  * Returns 0 on success, < 0 on error
 113  */
 114 int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 115                 struct lttng_consumer_stream *stream)
 116 {
 117         int ret = 0;
 118
 119         ret = ustctl_snapshot(stream->chan->handle, stream->buf);
 120         if (ret != 0) {
 121                 errno = -ret;
 122                 PERROR("Getting sub-buffer snapshot.");
 123         }
 124
 125         return ret;
 126 }
 127
 128 /*
 129  * Get the produced position
 130  *
 131  * Returns 0 on success, < 0 on error
 132  */
 133 int lttng_ustconsumer_get_produced_snapshot(
 134                 struct lttng_consumer_local_data *ctx,
 135                 struct lttng_consumer_stream *stream,
 136                 unsigned long *pos)
 137 {
 138         int ret;
 139
 140         ret = ustctl_snapshot_get_produced(stream->chan->handle,
 141                         stream->buf, pos);
 142         if (ret != 0) {
 143                 errno = -ret;
 144                 PERROR("kernctl_snapshot_get_produced");
 145         }
 146
 147         return ret;
 148 }
 149
 150 int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 151                 int sock, struct pollfd *consumer_sockpoll)
 152 {
 153         ssize_t ret;
 154         struct lttcomm_consumer_msg msg;
 155
 156         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 157         if (ret != sizeof(msg)) {
 158                 lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 159                 return ret;
 160         }
 161         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 162                 return -ENOENT;
 163         }
 164
 165         switch (msg.cmd_type) {
 166         case LTTNG_CONSUMER_ADD_CHANNEL:
 167         {
 168                 struct lttng_consumer_channel *new_channel;
 169                 int fds[1];
 170                 size_t nb_fd = 1;
 171
 172                 /* block */
 173                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 174                         return -EINTR;
 175                 }
 176                 ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
 177                 if (ret != sizeof(fds)) {
 178                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 179                         return ret;
 180                 }
 181
 182                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 183
 184                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 185                                 fds[0], -1,
 186                                 msg.u.channel.mmap_len,
 187                                 msg.u.channel.max_sb_size);
 188                 if (new_channel == NULL) {
 189                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 190                         goto end_nosignal;
 191                 }
 192                 if (ctx->on_recv_channel != NULL) {
 193                         ret = ctx->on_recv_channel(new_channel);
 194                         if (ret == 0) {
 195                                 consumer_add_channel(new_channel);
 196                         } else if (ret < 0) {
 197                                 goto end_nosignal;
 198                         }
 199                 } else {
 200                         consumer_add_channel(new_channel);
 201                 }
 202                 goto end_nosignal;
 203         }
 204         case LTTNG_CONSUMER_ADD_STREAM:
 205         {
 206                 struct lttng_consumer_stream *new_stream;
 207                 int fds[2];
 208                 size_t nb_fd = 2;
 209
 210                 /* block */
 211                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 212                         return -EINTR;
 213                 }
 214                 ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
 215                 if (ret != sizeof(fds)) {
 216                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 217                         return ret;
 218                 }
 219
 220                 DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
 221                         fds[0], fds[1]);
 222                 assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
 223                 new_stream = consumer_allocate_stream(msg.u.channel.channel_key,
 224                                 msg.u.stream.stream_key,
 225                                 fds[0], fds[1],
 226                                 msg.u.stream.state,
 227                                 msg.u.stream.mmap_len,
 228                                 msg.u.stream.output,
 229                                 msg.u.stream.path_name,
 230                                 msg.u.stream.uid,
 231                                 msg.u.stream.gid);
 232                 if (new_stream == NULL) {
 233                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 234                         goto end;
 235                 }
 236                 if (ctx->on_recv_stream != NULL) {
 237                         ret = ctx->on_recv_stream(new_stream);
 238                         if (ret == 0) {
 239                                 consumer_add_stream(new_stream);
 240                         } else if (ret < 0) {
 241                                 goto end;
 242                         }
 243                 } else {
 244                         consumer_add_stream(new_stream);
 245                 }
 246                 break;
 247         }
 248         case LTTNG_CONSUMER_UPDATE_STREAM:
 249         {
 250                 return -ENOSYS;
 251 #if 0
 252                 if (ctx->on_update_stream != NULL) {
 253                         ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
 254                         if (ret == 0) {
 255                                 consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
 256                         } else if (ret < 0) {
 257                                 goto end;
 258                         }
 259                 } else {
 260                         consumer_change_stream_state(msg.u.stream.stream_key,
 261                                 msg.u.stream.state);
 262                 }
 263 #endif
 264                 break;
 265         }
 266         default:
 267                 break;
 268         }
 269 end:
 270         /*
 271          * Wake-up the other end by writing a null byte in the pipe
 272          * (non-blocking). Important note: Because writing into the
 273          * pipe is non-blocking (and therefore we allow dropping wakeup
 274          * data, as long as there is wakeup data present in the pipe
 275          * buffer to wake up the other end), the other end should
 276          * perform the following sequence for waiting:
 277          * 1) empty the pipe (reads).
 278          * 2) perform update operation.
 279          * 3) wait on the pipe (poll).
 280          */
 281         do {
 282                 ret = write(ctx->consumer_poll_pipe[1], "", 1);
 283         } while (ret == -1UL && errno == EINTR);
 284 end_nosignal:
 285         return 0;
 286 }
 287
 288 int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
 289 {
 290         struct lttng_ust_object_data obj;
 291
 292         obj.handle = -1;
 293         obj.shm_fd = chan->shm_fd;
 294         obj.wait_fd = chan->wait_fd;
 295         obj.memory_map_size = chan->mmap_len;
 296         chan->handle = ustctl_map_channel(&obj);
 297         if (!chan->handle) {
 298                 return -ENOMEM;
 299         }
 300         chan->wait_fd_is_copy = 1;
 301         chan->shm_fd = -1;
 302
 303         return 0;
 304 }
 305
 306 void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
 307 {
 308         ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
 309         stream->hangup_flush_done = 1;
 310 }
 311
 312 void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
 313 {
 314         ustctl_unmap_channel(chan->handle);
 315 }
 316
 317 int lttng_ustconsumer_allocate_stream(struct lttng_consumer_stream *stream)
 318 {
 319         struct lttng_ust_object_data obj;
 320         int ret;
 321
 322         obj.handle = -1;
 323         obj.shm_fd = stream->shm_fd;
 324         obj.wait_fd = stream->wait_fd;
 325         obj.memory_map_size = stream->mmap_len;
 326         ret = ustctl_add_stream(stream->chan->handle, &obj);
 327         if (ret)
 328                 return ret;
 329         stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
 330         if (!stream->buf)
 331                 return -EBUSY;
 332         /* ustctl_open_stream_read has closed the shm fd. */
 333         stream->wait_fd_is_copy = 1;
 334         stream->shm_fd = -1;
 335
 336         stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
 337         if (!stream->mmap_base) {
 338                 return -EINVAL;
 339         }
 340
 341         return 0;
 342 }
 343
 344 void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
 345 {
 346         ustctl_close_stream_read(stream->chan->handle, stream->buf);
 347 }
 348
 349
 350 int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 351                 struct lttng_consumer_local_data *ctx)
 352 {
 353         unsigned long len;
 354         int err;
 355         long ret = 0;
 356         struct lttng_ust_shm_handle *handle;
 357         struct lttng_ust_lib_ring_buffer *buf;
 358         char dummy;
 359         ssize_t readlen;
 360
 361         DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
 362                 stream->wait_fd, stream->key);
 363
 364         /* We can consume the 1 byte written into the wait_fd by UST */
 365         if (!stream->hangup_flush_done) {
 366                 do {
 367                         readlen = read(stream->wait_fd, &dummy, 1);
 368                 } while (readlen == -1 && errno == EINTR);
 369                 if (readlen == -1) {
 370                         ret = readlen;
 371                         goto end;
 372                 }
 373         }
 374
 375         buf = stream->buf;
 376         handle = stream->chan->handle;
 377         /* Get the next subbuffer */
 378         err = ustctl_get_next_subbuf(handle, buf);
 379         if (err != 0) {
 380                 ret = -ret;     /* ustctl_get_next_subbuf returns negative, caller expect positive. */
 381                 /*
 382                  * This is a debug message even for single-threaded consumer,
 383                  * because poll() have more relaxed criterions than get subbuf,
 384                  * so get_subbuf may fail for short race windows where poll()
 385                  * would issue wakeups.
 386                  */
 387                 DBG("Reserving sub buffer failed (everything is normal, "
 388                                 "it is due to concurrency)");
 389                 goto end;
 390         }
 391         assert(stream->output == LTTNG_EVENT_MMAP);
 392         /* read the used subbuffer size */
 393         err = ustctl_get_padded_subbuf_size(handle, buf, &len);
 394         assert(err == 0);
 395         /* write the subbuffer to the tracefile */
 396         ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
 397         if (ret != len) {
 398                 /*
 399                  * display the error but continue processing to try
 400                  * to release the subbuffer
 401                  */
 402                 ERR("Error writing to tracefile");
 403         }
 404         err = ustctl_put_next_subbuf(handle, buf);
 405         assert(err == 0);
 406 end:
 407         return ret;
 408 }
 409
 410 int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 411 {
 412         int ret;
 413
 414         /* Opening the tracefile in write mode */
 415         if (stream->path_name != NULL) {
 416                 ret = run_as_open(stream->path_name,
 417                                 O_WRONLY|O_CREAT|O_TRUNC,
 418                                 S_IRWXU|S_IRWXG|S_IRWXO,
 419                                 stream->uid, stream->gid);
 420                 if (ret < 0) {
 421                         ERR("Opening %s", stream->path_name);
 422                         PERROR("open");
 423                         goto error;
 424                 }
 425                 stream->out_fd = ret;
 426         }
 427
 428         /* we return 0 to let the library handle the FD internally */
 429         return 0;
 430
 431 error:
 432         return ret;
 433 }