plugins/ctf/common/msg-iter/msg-iter.h

   1 #ifndef CTF_MSG_ITER_H
   2 #define CTF_MSG_ITER_H
   3
   4 /*
   5  * Babeltrace - CTF message iterator
   6  *                  ¯¯¯¯¯        ¯¯¯¯
   7  * Copyright (c) 2015-2016 EfficiOS Inc. and Linux Foundation
   8  * Copyright (c) 2015-2016 Philippe Proulx <pproulx@efficios.com>
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  23  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  26  * SOFTWARE.
  27  */
  28
  29 #include <stdint.h>
  30 #include <stdio.h>
  31 #include <stddef.h>
  32 #include <babeltrace/babeltrace.h>
  33 #include <babeltrace/babeltrace-internal.h>
  34
  35 #include "../metadata/ctf-meta.h"
  36
  37 /**
  38  * @file ctf-msg-iter.h
  39  *
  40  * CTF message iterator
  41  *     ¯¯¯¯¯        ¯¯¯¯
  42  * This is a common internal API used by CTF source plugins. It allows
  43  * one to get messages from a user-provided medium.
  44  */
  45
  46 /**
  47  * Medium operations status codes.
  48  */
  49 enum bt_msg_iter_medium_status {
  50         /**
  51          * End of file.
  52          *
  53          * The medium function called by the message iterator
  54          * function reached the end of the file.
  55          */
  56         BT_MSG_ITER_MEDIUM_STATUS_EOF = 1,
  57
  58         /**
  59          * There is no data available right now, try again later.
  60          */
  61         BT_MSG_ITER_MEDIUM_STATUS_AGAIN = 11,
  62
  63         /** Unsupported operation. */
  64         BT_MSG_ITER_MEDIUM_STATUS_UNSUPPORTED = -3,
  65
  66         /** Invalid argument. */
  67         BT_MSG_ITER_MEDIUM_STATUS_INVAL = -2,
  68
  69         /** General error. */
  70         BT_MSG_ITER_MEDIUM_STATUS_ERROR = -1,
  71
  72         /** Everything okay. */
  73         BT_MSG_ITER_MEDIUM_STATUS_OK = 0,
  74 };
  75
  76 /**
  77  * CTF message iterator API status code.
  78  */
  79 enum bt_msg_iter_status {
  80         /**
  81          * End of file.
  82          *
  83          * The medium function called by the message iterator
  84          * function reached the end of the file.
  85          */
  86         BT_MSG_ITER_STATUS_EOF = BT_MSG_ITER_MEDIUM_STATUS_EOF,
  87
  88         /**
  89          * There is no data available right now, try again later.
  90          *
  91          * Some condition resulted in the
  92          * bt_msg_iter_medium_ops::request_bytes() user function not
  93          * having access to any data now. You should retry calling the
  94          * last called message iterator function once the situation
  95          * is resolved.
  96          */
  97         BT_MSG_ITER_STATUS_AGAIN = BT_MSG_ITER_MEDIUM_STATUS_AGAIN,
  98
  99         /** Invalid argument. */
 100         BT_MSG_ITER_STATUS_INVAL = BT_MSG_ITER_MEDIUM_STATUS_INVAL,
 101
 102         /** Unsupported operation. */
 103         BT_MSG_ITER_STATUS_UNSUPPORTED = BT_MSG_ITER_MEDIUM_STATUS_UNSUPPORTED,
 104
 105         /** General error. */
 106         BT_MSG_ITER_STATUS_ERROR = BT_MSG_ITER_MEDIUM_STATUS_ERROR,
 107
 108         /** Everything okay. */
 109         BT_MSG_ITER_STATUS_OK = 0,
 110 };
 111
 112 /**
 113  * CTF message iterator seek operation directives.
 114  */
 115 enum bt_msg_iter_seek_whence {
 116         /**
 117          * Set the iterator's position to an absolute offset in the underlying
 118          * medium.
 119          */
 120         BT_MSG_ITER_SEEK_WHENCE_SET,
 121 };
 122
 123 /**
 124  * Medium operations.
 125  *
 126  * Those user functions are called by the message iterator
 127  * functions to request medium actions.
 128  */
 129 struct bt_msg_iter_medium_ops {
 130         /**
 131          * Returns the next byte buffer to be used by the binary file
 132          * reader to deserialize binary data.
 133          *
 134          * This function \em must be defined.
 135          *
 136          * The purpose of this function is to return a buffer of bytes
 137          * to the message iterator, of a maximum of \p request_sz
 138          * bytes. If this function cannot return a buffer of at least
 139          * \p request_sz bytes, it may return a smaller buffer. In
 140          * either cases, \p buffer_sz must be set to the returned buffer
 141          * size (in bytes).
 142          *
 143          * The returned buffer's ownership remains the medium, in that
 144          * it won't be freed by the message iterator functions. The
 145          * returned buffer won't be modified by the message
 146          * iterator functions either.
 147          *
 148          * When this function is called for the first time for a given
 149          * file, the offset within the file is considered to be 0. The
 150          * next times this function is called, the returned buffer's
 151          * byte offset within the complete file must be the previous
 152          * offset plus the last returned value of \p buffer_sz by this
 153          * medium.
 154          *
 155          * This function must return one of the following statuses:
 156          *
 157          *   - <b>#BT_MSG_ITER_MEDIUM_STATUS_OK</b>: Everything
 158          *     is okay, i.e. \p buffer_sz is set to a positive value
 159          *     reflecting the number of available bytes in the buffer
 160          *     starting at the address written in \p buffer_addr.
 161          *   - <b>#BT_MSG_ITER_MEDIUM_STATUS_AGAIN</b>: No data is
 162          *     available right now. In this case, the message
 163          *     iterator function called by the user returns
 164          *     #BT_MSG_ITER_STATUS_AGAIN, and it is the user's
 165          *     responsibility to make sure enough data becomes available
 166          *     before calling the \em same message iterator
 167          *     function again to continue the decoding process.
 168          *   - <b>#BT_MSG_ITER_MEDIUM_STATUS_EOF</b>: The end of
 169          *     the file was reached, and no more data will ever be
 170          *     available for this file. In this case, the message
 171          *     iterator function called by the user returns
 172          *     #BT_MSG_ITER_STATUS_EOF. This must \em not be
 173          *     returned when returning at least one byte of data to the
 174          *     caller, i.e. this must be returned when there's
 175          *     absolutely nothing left; should the request size be
 176          *     larger than what's left in the file, this function must
 177          *     return what's left, setting \p buffer_sz to the number of
 178          *     remaining bytes, and return
 179          *     #BT_MSG_ITER_MEDIUM_STATUS_EOF on the \em following
 180          *     call.
 181          *   - <b>#BT_MSG_ITER_MEDIUM_STATUS_ERROR</b>: A fatal
 182          *     error occured during this operation. In this case, the
 183          *     message iterator function called by the user returns
 184          *     #BT_MSG_ITER_STATUS_ERROR.
 185          *
 186          * If #BT_MSG_ITER_MEDIUM_STATUS_OK is not returned, the
 187          * values of \p buffer_sz and \p buffer_addr are \em ignored by
 188          * the caller.
 189          *
 190          * @param request_sz    Requested buffer size (bytes)
 191          * @param buffer_addr   Returned buffer address
 192          * @param buffer_sz     Returned buffer's size (bytes)
 193          * @param data          User data
 194          * @returns             Status code (see description above)
 195          */
 196         enum bt_msg_iter_medium_status (* request_bytes)(
 197                         size_t request_sz, uint8_t **buffer_addr,
 198                         size_t *buffer_sz, void *data);
 199
 200         /**
 201          * Repositions the underlying stream's position.
 202          *
 203          * This *optional* method repositions the underlying stream
 204          * to a given absolute or relative position, as indicated by
 205          * the whence directive.
 206          *
 207          * @param whence        One of #bt_msg_iter_seek_whence values
 208          * @param offset        Offset to use for the given directive
 209          * @param data          User data
 210          * @returns             One of #bt_msg_iter_medium_status values
 211          */
 212         enum bt_msg_iter_medium_status (* seek)(
 213                         enum bt_msg_iter_seek_whence whence,
 214                         off_t offset, void *data);
 215
 216         /**
 217          * Returns a stream instance (weak reference) for the given
 218          * stream class.
 219          *
 220          * This is called after a packet header is read, and the
 221          * corresponding stream class is found by the message
 222          * iterator.
 223          *
 224          * @param stream_class  Stream class of the stream to get
 225          * @param stream_id     Stream (instance) ID of the stream
 226          *                      to get (-1ULL if not available)
 227          * @param data          User data
 228          * @returns             Stream instance (weak reference) or
 229          *                      \c NULL on error
 230          */
 231         bt_stream * (* borrow_stream)(
 232                         bt_stream_class *stream_class,
 233                         int64_t stream_id, void *data);
 234 };
 235
 236 /** CTF message iterator. */
 237 struct bt_msg_iter;
 238
 239 /**
 240  * Creates a CTF message iterator.
 241  *
 242  * Upon successful completion, the reference count of \p trace is
 243  * incremented.
 244  *
 245  * @param trace                 Trace to read
 246  * @param max_request_sz        Maximum buffer size, in bytes, to
 247  *                              request to
 248  *                              bt_msg_iter_medium_ops::request_bytes()
 249  *                              at a time
 250  * @param medops                Medium operations
 251  * @param medops_data           User data (passed to medium operations)
 252  * @returns                     New CTF message iterator on
 253  *                              success, or \c NULL on error
 254  */
 255 BT_HIDDEN
 256 struct bt_msg_iter *bt_msg_iter_create(struct ctf_trace_class *tc,
 257         size_t max_request_sz, struct bt_msg_iter_medium_ops medops,
 258         void *medops_data);
 259
 260 /**
 261  * Destroys a CTF message iterator, freeing all internal resources.
 262  *
 263  * The registered trace's reference count is decremented.
 264  *
 265  * @param msg_iter              CTF message iterator
 266  */
 267 BT_HIDDEN
 268 void bt_msg_iter_destroy(struct bt_msg_iter *msg_iter);
 269
 270 /**
 271  * Returns the next message from a CTF message iterator.
 272  *
 273  * Upon successful completion, #BT_MSG_ITER_STATUS_OK is
 274  * returned, and the next message is written to \p msg.
 275  * In this case, the caller is responsible for calling
 276  * bt_message_put() on the returned message.
 277  *
 278  * If this function returns #BT_MSG_ITER_STATUS_AGAIN, the caller
 279  * should make sure that data becomes available to its medium, and
 280  * call this function again, until another status is returned.
 281  *
 282  * @param msg_iter              CTF message iterator
 283  * @param message               Returned message if the function's
 284  *                              return value is #BT_MSG_ITER_STATUS_OK
 285  * @returns                     One of #bt_msg_iter_status values
 286  */
 287 BT_HIDDEN
 288 enum bt_msg_iter_status bt_msg_iter_get_next_message(
 289                 struct bt_msg_iter *notit,
 290                 bt_self_message_iterator *msg_iter,
 291                 bt_message **message);
 292
 293 struct bt_msg_iter_packet_properties {
 294         uint64_t exp_packet_total_size;
 295         uint64_t exp_packet_content_size;
 296         uint64_t stream_class_id;
 297         int64_t data_stream_id;
 298
 299         struct {
 300                 uint64_t discarded_events;
 301                 uint64_t packets;
 302                 uint64_t beginning_clock;
 303                 uint64_t end_clock;
 304         } snapshots;
 305 };
 306
 307 BT_HIDDEN
 308 enum bt_msg_iter_status bt_msg_iter_get_packet_properties(
 309                 struct bt_msg_iter *notit,
 310                 struct bt_msg_iter_packet_properties *props);
 311
 312 BT_HIDDEN
 313 void bt_msg_iter_set_medops_data(struct bt_msg_iter *notit,
 314                 void *medops_data);
 315
 316 BT_HIDDEN
 317 enum bt_msg_iter_status bt_msg_iter_seek(
 318                 struct bt_msg_iter *notit, off_t offset);
 319
 320 /*
 321  * Get the current packet's offset in bytes relative to the media's initial
 322  * position.
 323  */
 324 BT_HIDDEN
 325 off_t bt_msg_iter_get_current_packet_offset(
 326                 struct bt_msg_iter *notit);
 327
 328 /* Get the current packet's size (in bits). */
 329 BT_HIDDEN
 330 off_t bt_msg_iter_get_current_packet_size(
 331                 struct bt_msg_iter *notit);
 332
 333 /*
 334  * Resets the iterator so that the next requested medium bytes are
 335  * assumed to be the first bytes of a new stream. The first message
 336  * which this iterator emits after calling bt_msg_iter_reset() is a
 337  * BT_MESSAGE_TYPE_STREAM_BEGINNING one.
 338  */
 339 BT_HIDDEN
 340 void bt_msg_iter_reset(struct bt_msg_iter *notit);
 341
 342 /*
 343  * Notify the iterator that the trace class changed somehow (new
 344  * stream/event classes).
 345  */
 346 BT_HIDDEN
 347 void bt_msg_trace_class_changed(struct bt_msg_iter *notit);
 348
 349 static inline
 350 const char *bt_msg_iter_medium_status_string(
 351                 enum bt_msg_iter_medium_status status)
 352 {
 353         switch (status) {
 354         case BT_MSG_ITER_MEDIUM_STATUS_EOF:
 355                 return "BT_MSG_ITER_MEDIUM_STATUS_EOF";
 356         case BT_MSG_ITER_MEDIUM_STATUS_AGAIN:
 357                 return "BT_MSG_ITER_MEDIUM_STATUS_AGAIN";
 358         case BT_MSG_ITER_MEDIUM_STATUS_INVAL:
 359                 return "BT_MSG_ITER_MEDIUM_STATUS_INVAL";
 360         case BT_MSG_ITER_MEDIUM_STATUS_ERROR:
 361                 return "BT_MSG_ITER_MEDIUM_STATUS_ERROR";
 362         case BT_MSG_ITER_MEDIUM_STATUS_OK:
 363                 return "BT_MSG_ITER_MEDIUM_STATUS_OK";
 364         default:
 365                 return "(unknown)";
 366         }
 367 }
 368
 369 static inline
 370 const char *bt_msg_iter_status_string(
 371                 enum bt_msg_iter_status status)
 372 {
 373         switch (status) {
 374         case BT_MSG_ITER_STATUS_EOF:
 375                 return "BT_MSG_ITER_STATUS_EOF";
 376         case BT_MSG_ITER_STATUS_AGAIN:
 377                 return "BT_MSG_ITER_STATUS_AGAIN";
 378         case BT_MSG_ITER_STATUS_INVAL:
 379                 return "BT_MSG_ITER_STATUS_INVAL";
 380         case BT_MSG_ITER_STATUS_ERROR:
 381                 return "BT_MSG_ITER_STATUS_ERROR";
 382         case BT_MSG_ITER_STATUS_OK:
 383                 return "BT_MSG_ITER_STATUS_OK";
 384         default:
 385                 return "(unknown)";
 386         }
 387 }
 388
 389 #endif /* CTF_MSG_ITER_H */