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