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