liblttng-kconsumer/lttng-kconsumer.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
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; only version 2
   8  * of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18  */
  19
  20 #define _GNU_SOURCE
  21 #include <assert.h>
  22 #include <fcntl.h>
  23 #include <poll.h>
  24 #include <pthread.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/mman.h>
  28 #include <sys/socket.h>
  29 #include <sys/types.h>
  30 #include <unistd.h>
  31
  32 #include <lttng-kernel-ctl.h>
  33 #include <lttng-sessiond-comm.h>
  34 #include <lttng/lttng-kconsumer.h>
  35 #include <lttngerr.h>
  36
  37 extern struct lttng_consumer_global_data consumer_data;
  38 extern int consumer_poll_timeout;
  39 extern volatile int consumer_quit;
  40
  41 /*
  42  * Mmap the ring buffer, read it and write the data to the tracefile.
  43  *
  44  * Returns the number of bytes written
  45  */
  46 int lttng_kconsumer_on_read_subbuffer_mmap(
  47                 struct lttng_consumer_local_data *ctx,
  48                 struct lttng_consumer_stream *stream, unsigned long len)
  49 {
  50         unsigned long mmap_offset;
  51         long ret = 0;
  52         off_t orig_offset = stream->out_fd_offset;
  53         int fd = stream->wait_fd;
  54         int outfd = stream->out_fd;
  55
  56         /* get the offset inside the fd to mmap */
  57         ret = kernctl_get_mmap_read_offset(fd, &mmap_offset);
  58         if (ret != 0) {
  59                 ret = -errno;
  60                 perror("kernctl_get_mmap_read_offset");
  61                 goto end;
  62         }
  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                         ret = -errno;
  70                         perror("Error in file write");
  71                         goto end;
  72                 }
  73                 /* This won't block, but will start writeout asynchronously */
  74                 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 int lttng_kconsumer_on_read_subbuffer_splice(
  93                 struct lttng_consumer_local_data *ctx,
  94                 struct lttng_consumer_stream *stream, unsigned long len)
  95 {
  96         long ret = 0;
  97         loff_t offset = 0;
  98         off_t orig_offset = stream->out_fd_offset;
  99         int fd = stream->wait_fd;
 100         int outfd = stream->out_fd;
 101
 102         while (len > 0) {
 103                 DBG("splice chan to pipe offset %lu (fd : %d)",
 104                                 (unsigned long)offset, fd);
 105                 ret = splice(fd, &offset, ctx->consumer_thread_pipe[1], NULL, len,
 106                                 SPLICE_F_MOVE | SPLICE_F_MORE);
 107                 DBG("splice chan to pipe ret %ld", ret);
 108                 if (ret < 0) {
 109                         ret = errno;
 110                         perror("Error in relay splice");
 111                         goto splice_error;
 112                 }
 113
 114                 ret = splice(ctx->consumer_thread_pipe[0], NULL, outfd, NULL, ret,
 115                                 SPLICE_F_MOVE | SPLICE_F_MORE);
 116                 DBG("splice pipe to file %ld", ret);
 117                 if (ret < 0) {
 118                         ret = errno;
 119                         perror("Error in file splice");
 120                         goto splice_error;
 121                 }
 122                 len -= ret;
 123                 /* This won't block, but will start writeout asynchronously */
 124                 sync_file_range(outfd, stream->out_fd_offset, ret,
 125                                 SYNC_FILE_RANGE_WRITE);
 126                 stream->out_fd_offset += ret;
 127         }
 128         lttng_consumer_sync_trace_file(stream, orig_offset);
 129
 130         goto end;
 131
 132 splice_error:
 133         /* send the appropriate error description to sessiond */
 134         switch(ret) {
 135         case EBADF:
 136                 lttng_consumer_send_error(ctx, CONSUMERD_SPLICE_EBADF);
 137                 break;
 138         case EINVAL:
 139                 lttng_consumer_send_error(ctx, CONSUMERD_SPLICE_EINVAL);
 140                 break;
 141         case ENOMEM:
 142                 lttng_consumer_send_error(ctx, CONSUMERD_SPLICE_ENOMEM);
 143                 break;
 144         case ESPIPE:
 145                 lttng_consumer_send_error(ctx, CONSUMERD_SPLICE_ESPIPE);
 146                 break;
 147         }
 148
 149 end:
 150         return ret;
 151 }
 152
 153 /*
 154  * Take a snapshot for a specific fd
 155  *
 156  * Returns 0 on success, < 0 on error
 157  */
 158 int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 159                 struct lttng_consumer_stream *stream)
 160 {
 161         int ret = 0;
 162         int infd = stream->wait_fd;
 163
 164         ret = kernctl_snapshot(infd);
 165         if (ret != 0) {
 166                 ret = errno;
 167                 perror("Getting sub-buffer snapshot.");
 168         }
 169
 170         return ret;
 171 }
 172
 173 /*
 174  * Get the produced position
 175  *
 176  * Returns 0 on success, < 0 on error
 177  */
 178 int lttng_kconsumer_get_produced_snapshot(
 179                 struct lttng_consumer_local_data *ctx,
 180                 struct lttng_consumer_stream *stream,
 181                 unsigned long *pos)
 182 {
 183         int ret;
 184         int infd = stream->wait_fd;
 185
 186         ret = kernctl_snapshot_get_produced(infd, pos);
 187         if (ret != 0) {
 188                 ret = errno;
 189                 perror("kernctl_snapshot_get_produced");
 190         }
 191
 192         return ret;
 193 }
 194
 195 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 196                 int sock, struct pollfd *consumer_sockpoll)
 197 {
 198         ssize_t ret;
 199         struct lttcomm_consumer_msg msg;
 200
 201         ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 202         if (ret != sizeof(msg)) {
 203                 lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 204                 return ret;
 205         }
 206         if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
 207                 return -ENOENT;
 208         }
 209
 210         switch (msg.cmd_type) {
 211         case LTTNG_CONSUMER_ADD_CHANNEL:
 212         {
 213                 struct lttng_consumer_channel *new_channel;
 214
 215                 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
 216                 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
 217                                 -1, -1,
 218                                 msg.u.channel.mmap_len,
 219                                 msg.u.channel.max_sb_size);
 220                 if (new_channel == NULL) {
 221                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 222                         goto end_nosignal;
 223                 }
 224                 if (ctx->on_recv_channel != NULL) {
 225                         ret = ctx->on_recv_channel(new_channel);
 226                         if (ret == 0) {
 227                                 consumer_add_channel(new_channel);
 228                         } else if (ret < 0) {
 229                                 goto end_nosignal;
 230                         }
 231                 } else {
 232                         consumer_add_channel(new_channel);
 233                 }
 234                 goto end_nosignal;
 235         }
 236         case LTTNG_CONSUMER_ADD_STREAM:
 237         {
 238                 struct lttng_consumer_stream *new_stream;
 239                 int fds[1];
 240                 size_t nb_fd = 1;
 241
 242                 /* block */
 243                 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 244                         return -EINTR;
 245                 }
 246                 ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
 247                 if (ret != sizeof(fds)) {
 248                         lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
 249                         return ret;
 250                 }
 251                 if (nb_fd < 2)
 252                         fds[1] = fds[0];        /* duplicate same fd if recv only one */
 253
 254                 DBG("consumer_add_stream %s (%d,%d)", msg.u.stream.path_name,
 255                         fds[0], fds[1]);
 256                 new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
 257                                 msg.u.stream.stream_key,
 258                                 fds[0], fds[1],
 259                                 msg.u.stream.state,
 260                                 msg.u.stream.mmap_len,
 261                                 msg.u.stream.output,
 262                                 msg.u.stream.path_name);
 263                 if (new_stream == NULL) {
 264                         lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
 265                         goto end;
 266                 }
 267                 if (ctx->on_recv_stream != NULL) {
 268                         ret = ctx->on_recv_stream(new_stream);
 269                         if (ret == 0) {
 270                                 consumer_add_stream(new_stream);
 271                         } else if (ret < 0) {
 272                                 goto end;
 273                         }
 274                 } else {
 275                         consumer_add_stream(new_stream);
 276                 }
 277                 break;
 278         }
 279         case LTTNG_CONSUMER_UPDATE_STREAM:
 280         {
 281                 if (ctx->on_update_stream != NULL) {
 282                         ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
 283                         if (ret == 0) {
 284                                 consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
 285                         } else if (ret < 0) {
 286                                 goto end;
 287                         }
 288                 } else {
 289                         consumer_change_stream_state(msg.u.stream.stream_key,
 290                                 msg.u.stream.state);
 291                 }
 292                 break;
 293         }
 294         default:
 295                 break;
 296         }
 297 end:
 298         /* signal the poll thread */
 299         ret = write(ctx->consumer_poll_pipe[1], "4", 1);
 300         if (ret < 0) {
 301                 perror("write consumer poll");
 302         }
 303 end_nosignal:
 304         return 0;
 305 }