src/plugins/ctf/common/src/msg-iter/msg-iter.hpp

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (c) 2015-2016 EfficiOS Inc. and Linux Foundation
   5  * Copyright (c) 2015-2016 Philippe Proulx <pproulx@efficios.com>
   6  *
   7  * Babeltrace - CTF message iterator
   8  */
   9
  10 #ifndef CTF_MSG_ITER_H
  11 #define CTF_MSG_ITER_H
  12
  13 #include <stddef.h>
  14 #include <stdint.h>
  15 #include <stdio.h>
  16
  17 #include <babeltrace2/babeltrace.h>
  18
  19 #include "../metadata/tsdl/ctf-meta.hpp"
  20
  21 namespace bt2c {
  22
  23 class Logger;
  24
  25 } /* namespace bt2c */
  26
  27 /**
  28  * @file ctf-msg-iter.h
  29  *
  30  * CTF message iterator
  31  *
  32  * This is a common internal API used by CTF source plugins. It allows
  33  * one to get messages from a user-provided medium.
  34  */
  35
  36 /**
  37  * Medium operations status codes.  These use the same values as
  38  * libbabeltrace2.
  39  */
  40 enum ctf_msg_iter_medium_status
  41 {
  42     /**
  43      * End of file.
  44      *
  45      * The medium function called by the message iterator
  46      * function reached the end of the file.
  47      */
  48     CTF_MSG_ITER_MEDIUM_STATUS_EOF = 1,
  49
  50     /**
  51      * There is no data available right now, try again later.
  52      */
  53     CTF_MSG_ITER_MEDIUM_STATUS_AGAIN = 11,
  54
  55     /** General error. */
  56     CTF_MSG_ITER_MEDIUM_STATUS_ERROR = -1,
  57
  58     /** Memory error. */
  59     CTF_MSG_ITER_MEDIUM_STATUS_MEMORY_ERROR = -12,
  60
  61     /** Everything okay. */
  62     CTF_MSG_ITER_MEDIUM_STATUS_OK = 0,
  63 };
  64
  65 inline const char *format_as(const ctf_msg_iter_medium_status status) noexcept
  66 {
  67     switch (status) {
  68     case CTF_MSG_ITER_MEDIUM_STATUS_EOF:
  69         return "EOF";
  70
  71     case CTF_MSG_ITER_MEDIUM_STATUS_AGAIN:
  72         return "AGAIN";
  73
  74     case CTF_MSG_ITER_MEDIUM_STATUS_ERROR:
  75         return "ERROR";
  76
  77     case CTF_MSG_ITER_MEDIUM_STATUS_MEMORY_ERROR:
  78         return "MEMORY_ERROR";
  79
  80     case CTF_MSG_ITER_MEDIUM_STATUS_OK:
  81         return "OK";
  82     }
  83
  84     bt_common_abort();
  85 }
  86
  87 /**
  88  * CTF message iterator API status code.
  89  */
  90 enum ctf_msg_iter_status
  91 {
  92     /**
  93      * End of file.
  94      *
  95      * The medium function called by the message iterator
  96      * function reached the end of the file.
  97      */
  98     CTF_MSG_ITER_STATUS_EOF = CTF_MSG_ITER_MEDIUM_STATUS_EOF,
  99
 100     /**
 101      * There is no data available right now, try again later.
 102      *
 103      * Some condition resulted in the
 104      * ctf_msg_iter_medium_ops::request_bytes() user function not
 105      * having access to any data now. You should retry calling the
 106      * last called message iterator function once the situation
 107      * is resolved.
 108      */
 109     CTF_MSG_ITER_STATUS_AGAIN = CTF_MSG_ITER_MEDIUM_STATUS_AGAIN,
 110
 111     /** General error. */
 112     CTF_MSG_ITER_STATUS_ERROR = CTF_MSG_ITER_MEDIUM_STATUS_ERROR,
 113
 114     /** Memory error. */
 115     CTF_MSG_ITER_STATUS_MEMORY_ERROR = CTF_MSG_ITER_MEDIUM_STATUS_MEMORY_ERROR,
 116
 117     /** Everything okay. */
 118     CTF_MSG_ITER_STATUS_OK = CTF_MSG_ITER_MEDIUM_STATUS_OK,
 119 };
 120
 121 inline const char *format_as(ctf_msg_iter_status status) noexcept
 122 {
 123     switch (status) {
 124     case CTF_MSG_ITER_STATUS_EOF:
 125         return "EOF";
 126
 127     case CTF_MSG_ITER_STATUS_AGAIN:
 128         return "AGAIN";
 129
 130     case CTF_MSG_ITER_STATUS_ERROR:
 131         return "ERROR";
 132
 133     case CTF_MSG_ITER_STATUS_MEMORY_ERROR:
 134         return "MEMORY_ERROR";
 135
 136     case CTF_MSG_ITER_STATUS_OK:
 137         return "OK";
 138     }
 139
 140     bt_common_abort();
 141 }
 142
 143 /**
 144  * Medium operations.
 145  *
 146  * Those user functions are called by the message iterator
 147  * functions to request medium actions.
 148  */
 149 struct ctf_msg_iter_medium_ops
 150 {
 151     /**
 152      * Returns the next byte buffer to be used by the binary file
 153      * reader to deserialize binary data.
 154      *
 155      * This function \em must be defined.
 156      *
 157      * The purpose of this function is to return a buffer of bytes
 158      * to the message iterator, of a maximum of \p request_sz
 159      * bytes. If this function cannot return a buffer of at least
 160      * \p request_sz bytes, it may return a smaller buffer. In
 161      * either cases, \p buffer_sz must be set to the returned buffer
 162      * size (in bytes).
 163      *
 164      * The returned buffer's ownership remains the medium, in that
 165      * it won't be freed by the message iterator functions. The
 166      * returned buffer won't be modified by the message
 167      * iterator functions either.
 168      *
 169      * When this function is called for the first time for a given
 170      * file, the offset within the file is considered to be 0. The
 171      * next times this function is called, the returned buffer's
 172      * byte offset within the complete file must be the previous
 173      * offset plus the last returned value of \p buffer_sz by this
 174      * medium.
 175      *
 176      * This function must return one of the following statuses:
 177      *
 178      *   - <b>#CTF_MSG_ITER_MEDIUM_STATUS_OK</b>: Everything
 179      *     is okay, i.e. \p buffer_sz is set to a positive value
 180      *     reflecting the number of available bytes in the buffer
 181      *     starting at the address written in \p buffer_addr.
 182      *   - <b>#CTF_MSG_ITER_MEDIUM_STATUS_AGAIN</b>: No data is
 183      *     available right now. In this case, the message
 184      *     iterator function called by the user returns
 185      *     #CTF_MSG_ITER_STATUS_AGAIN, and it is the user's
 186      *     responsibility to make sure enough data becomes available
 187      *     before calling the \em same message iterator
 188      *     function again to continue the decoding process.
 189      *   - <b>#CTF_MSG_ITER_MEDIUM_STATUS_EOF</b>: The end of
 190      *     the file was reached, and no more data will ever be
 191      *     available for this file. In this case, the message
 192      *     iterator function called by the user returns
 193      *     #CTF_MSG_ITER_STATUS_EOF. This must \em not be
 194      *     returned when returning at least one byte of data to the
 195      *     caller, i.e. this must be returned when there's
 196      *     absolutely nothing left; should the request size be
 197      *     larger than what's left in the file, this function must
 198      *     return what's left, setting \p buffer_sz to the number of
 199      *     remaining bytes, and return
 200      *     #CTF_MSG_ITER_MEDIUM_STATUS_EOF on the \em following
 201      *     call.
 202      *   - <b>#CTF_MSG_ITER_MEDIUM_STATUS_ERROR</b>: A fatal
 203      *     error occurred during this operation. In this case, the
 204      *     message iterator function called by the user returns
 205      *     #CTF_MSG_ITER_STATUS_ERROR.
 206      *
 207      * If #CTF_MSG_ITER_MEDIUM_STATUS_OK is not returned, the
 208      * values of \p buffer_sz and \p buffer_addr are \em ignored by
 209      * the caller.
 210      *
 211      * @param request_sz        Requested buffer size (bytes)
 212      * @param buffer_addr       Returned buffer address
 213      * @param buffer_sz Returned buffer's size (bytes)
 214      * @param data              User data
 215      * @returns         Status code (see description above)
 216      */
 217     enum ctf_msg_iter_medium_status (*request_bytes)(size_t request_sz, uint8_t **buffer_addr,
 218                                                      size_t *buffer_sz, void *data);
 219
 220     /**
 221      * Repositions the underlying stream's position.
 222      *
 223      * This *optional* method repositions the underlying stream
 224      * to a given absolute position in the medium.
 225      *
 226      * @param offset    Offset to use for the given directive
 227      * @param data              User data
 228      * @returns         One of #ctf_msg_iter_medium_status values
 229      */
 230     enum ctf_msg_iter_medium_status (*seek)(off_t offset, void *data);
 231
 232     /**
 233      * Called when the message iterator wishes to inform the medium that it
 234      * is about to start a new packet.
 235      *
 236      * After the iterator has called switch_packet, the following call to
 237      * request_bytes must return the content at the start of the next
 238      * packet.   */
 239     enum ctf_msg_iter_medium_status (*switch_packet)(void *data);
 240
 241     /**
 242      * Returns a stream instance (weak reference) for the given
 243      * stream class.
 244      *
 245      * This is called after a packet header is read, and the
 246      * corresponding stream class is found by the message
 247      * iterator.
 248      *
 249      * @param stream_class      Stream class of the stream to get
 250      * @param stream_id Stream (instance) ID of the stream
 251      *                  to get (-1ULL if not available)
 252      * @param data              User data
 253      * @returns         Stream instance (weak reference) or
 254      *                  \c NULL on error
 255      */
 256     bt_stream *(*borrow_stream)(bt_stream_class *stream_class, int64_t stream_id, void *data);
 257 };
 258
 259 /** CTF message iterator. */
 260 struct ctf_msg_iter;
 261
 262 struct ctf_msg_iter_deleter
 263 {
 264     void operator()(ctf_msg_iter *iter) noexcept;
 265 };
 266
 267 using ctf_msg_iter_up = std::unique_ptr<ctf_msg_iter, ctf_msg_iter_deleter>;
 268
 269 /**
 270  * Creates a CTF message iterator.
 271  *
 272  * Upon successful completion, the reference count of \p trace is
 273  * incremented.
 274  *
 275  * @param trace                 Trace to read
 276  * @param max_request_sz        Maximum buffer size, in bytes, to
 277  *                              request to
 278  *                              ctf_msg_iter_medium_ops::request_bytes()
 279  *                              at a time
 280  * @param medops                Medium operations
 281  * @param medops_data           User data (passed to medium operations)
 282  * @returns                     New CTF message iterator on
 283  *                              success, or \c NULL on error
 284  */
 285 ctf_msg_iter_up ctf_msg_iter_create(struct ctf_trace_class *tc, size_t max_request_sz,
 286                                     struct ctf_msg_iter_medium_ops medops, void *medops_data,
 287                                     bt_self_message_iterator *self_msg_iter,
 288                                     const bt2c::Logger& logger);
 289
 290 /**
 291  * Destroys a CTF message iterator, freeing all internal resources.
 292  *
 293  * The registered trace's reference count is decremented.
 294  *
 295  * @param msg_iter              CTF message iterator
 296  */
 297 void ctf_msg_iter_destroy(struct ctf_msg_iter *msg_iter);
 298
 299 /**
 300  * Returns the next message from a CTF message iterator.
 301  *
 302  * Upon successful completion, #CTF_MSG_ITER_STATUS_OK is
 303  * returned, and the next message is written to \p msg.
 304  * In this case, the caller is responsible for calling
 305  * bt_message_put() on the returned message.
 306  *
 307  * If this function returns #CTF_MSG_ITER_STATUS_AGAIN, the caller
 308  * should make sure that data becomes available to its medium, and
 309  * call this function again, until another status is returned.
 310  *
 311  * @param msg_iter              CTF message iterator
 312  * @param message               Returned message if the function's
 313  *                              return value is #CTF_MSG_ITER_STATUS_OK
 314  * @returns                     One of #ctf_msg_iter_status values
 315  */
 316 enum ctf_msg_iter_status ctf_msg_iter_get_next_message(struct ctf_msg_iter *msg_it,
 317                                                        const bt_message **message);
 318
 319 struct ctf_msg_iter_packet_properties
 320 {
 321     int64_t exp_packet_total_size;
 322     int64_t exp_packet_content_size;
 323     uint64_t stream_class_id;
 324     int64_t data_stream_id;
 325
 326     struct
 327     {
 328         uint64_t discarded_events;
 329         uint64_t packets;
 330         uint64_t beginning_clock;
 331         uint64_t end_clock;
 332     } snapshots;
 333 };
 334
 335 enum ctf_msg_iter_status
 336 ctf_msg_iter_get_packet_properties(struct ctf_msg_iter *msg_it,
 337                                    struct ctf_msg_iter_packet_properties *props);
 338
 339 enum ctf_msg_iter_status
 340 ctf_msg_iter_curr_packet_first_event_clock_snapshot(struct ctf_msg_iter *msg_it,
 341                                                     uint64_t *first_event_cs);
 342
 343 enum ctf_msg_iter_status
 344 ctf_msg_iter_curr_packet_last_event_clock_snapshot(struct ctf_msg_iter *msg_it,
 345                                                    uint64_t *last_event_cs);
 346
 347 enum ctf_msg_iter_status ctf_msg_iter_seek(struct ctf_msg_iter *msg_it, off_t offset);
 348
 349 /*
 350  * Resets the iterator so that the next requested medium bytes are
 351  * assumed to be the first bytes of a new stream. Depending on
 352  * ctf_msg_iter_set_emit_stream_beginning_message(), the first message
 353  * which this iterator emits after calling ctf_msg_iter_reset() is of
 354  * type `CTF_MESSAGE_TYPE_STREAM_BEGINNING`.
 355  */
 356 void ctf_msg_iter_reset(struct ctf_msg_iter *msg_it);
 357
 358 /*
 359  * Like ctf_msg_iter_reset(), but preserves stream-dependent state.
 360  */
 361 void ctf_msg_iter_reset_for_next_stream_file(struct ctf_msg_iter *msg_it);
 362
 363 void ctf_msg_iter_set_dry_run(struct ctf_msg_iter *msg_it, bool val);
 364
 365 #endif /* CTF_MSG_ITER_H */