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