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

   1 #ifndef CTF_NOTIF_ITER_H
   2 #define CTF_NOTIF_ITER_H
   3
   4 /*
   5  * Babeltrace - CTF notification 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/ctf-ir/trace.h>
  33 #include <babeltrace/ctf-ir/fields.h>
  34 #include <babeltrace/ctf-ir/event.h>
  35 #include <babeltrace/babeltrace-internal.h>
  36
  37 /**
  38  * @file ctf-notif-iter.h
  39  *
  40  * CTF notification iterator
  41  *     ¯¯¯¯¯        ¯¯¯¯
  42  * This is a common internal API used by CTF source plugins. It allows
  43  * one to get notifications from a user-provided medium.
  44  */
  45
  46 /**
  47  * Medium operations status codes.
  48  */
  49 enum bt_ctf_notif_iter_medium_status {
  50         /**
  51          * End of file.
  52          *
  53          * The medium function called by the notification iterator
  54          * function reached the end of the file.
  55          */
  56         BT_CTF_NOTIF_ITER_MEDIUM_STATUS_EOF =   -4,
  57
  58         /**
  59          * There is no data available right now, try again later.
  60          */
  61         BT_CTF_NOTIF_ITER_MEDIUM_STATUS_AGAIN = -3,
  62
  63         /** Invalid argument. */
  64         BT_CTF_NOTIF_ITER_MEDIUM_STATUS_INVAL = -2,
  65
  66         /** General error. */
  67         BT_CTF_NOTIF_ITER_MEDIUM_STATUS_ERROR = -1,
  68
  69         /** Everything okay. */
  70         BT_CTF_NOTIF_ITER_MEDIUM_STATUS_OK =            0,
  71 };
  72
  73 /**
  74  * CTF notification iterator API status code.
  75  */
  76 enum bt_ctf_notif_iter_status {
  77         /**
  78          * End of file.
  79          *
  80          * The medium function called by the notification iterator
  81          * function reached the end of the file.
  82          */
  83         BT_CTF_NOTIF_ITER_STATUS_EOF =  -4,
  84
  85         /**
  86          * There is no data available right now, try again later.
  87          *
  88          * Some condition resulted in the
  89          * bt_ctf_notif_iter_medium_ops::request_bytes() user function not
  90          * having access to any data now. You should retry calling the
  91          * last called notification iterator function once the situation
  92          * is resolved.
  93          */
  94         BT_CTF_NOTIF_ITER_STATUS_AGAIN =        -3,
  95
  96         /** Invalid argument. */
  97         BT_CTF_NOTIF_ITER_STATUS_INVAL =        -2,
  98
  99         /** General error. */
 100         BT_CTF_NOTIF_ITER_STATUS_ERROR =        -1,
 101
 102         /** Everything okay. */
 103         BT_CTF_NOTIF_ITER_STATUS_OK =   0,
 104 };
 105
 106 /**
 107  * Medium operations.
 108  *
 109  * Those user functions are called by the notification iterator
 110  * functions to request medium actions.
 111  */
 112 struct bt_ctf_notif_iter_medium_ops {
 113         /**
 114          * Returns the next byte buffer to be used by the binary file
 115          * reader to deserialize binary data.
 116          *
 117          * This function \em must be defined.
 118          *
 119          * The purpose of this function is to return a buffer of bytes
 120          * to the notification iterator, of a maximum of \p request_sz
 121          * bytes. If this function cannot return a buffer of at least
 122          * \p request_sz bytes, it may return a smaller buffer. In
 123          * either cases, \p buffer_sz must be set to the returned buffer
 124          * size (in bytes).
 125          *
 126          * The returned buffer's ownership remains the medium, in that
 127          * it won't be freed by the notification iterator functions. The
 128          * returned buffer won't be modified by the notification
 129          * iterator functions either.
 130          *
 131          * When this function is called for the first time for a given
 132          * file, the offset within the file is considered to be 0. The
 133          * next times this function is called, the returned buffer's
 134          * byte offset within the complete file must be the previous
 135          * offset plus the last returned value of \p buffer_sz by this
 136          * medium.
 137          *
 138          * This function must return one of the following statuses:
 139          *
 140          *   - <b>#BT_CTF_NOTIF_ITER_MEDIUM_STATUS_OK</b>: Everything
 141          *     is okay, i.e. \p buffer_sz is set to a positive value
 142          *     reflecting the number of available bytes in the buffer
 143          *     starting at the address written in \p buffer_addr.
 144          *   - <b>#BT_CTF_NOTIF_ITER_MEDIUM_STATUS_AGAIN</b>: No data is
 145          *     available right now. In this case, the notification
 146          *     iterator function called by the user returns
 147          *     #BT_CTF_NOTIF_ITER_STATUS_AGAIN, and it is the user's
 148          *     responsibility to make sure enough data becomes available
 149          *     before calling the \em same notification iterator
 150          *     function again to continue the decoding process.
 151          *   - <b>#BT_CTF_NOTIF_ITER_MEDIUM_STATUS_EOF</b>: The end of
 152          *     the file was reached, and no more data will ever be
 153          *     available for this file. In this case, the notification
 154          *     iterator function called by the user returns
 155          *     #BT_CTF_NOTIF_ITER_STATUS_EOF. This must \em not be
 156          *     returned when returning at least one byte of data to the
 157          *     caller, i.e. this must be returned when there's
 158          *     absolutely nothing left; should the request size be
 159          *     larger than what's left in the file, this function must
 160          *     return what's left, setting \p buffer_sz to the number of
 161          *     remaining bytes, and return
 162          *     #BT_CTF_NOTIF_ITER_MEDIUM_STATUS_EOF on the \em following
 163          *     call.
 164          *   - <b>#BT_CTF_NOTIF_ITER_MEDIUM_STATUS_ERROR</b>: A fatal
 165          *     error occured during this operation. In this case, the
 166          *     notification iterator function called by the user returns
 167          *     #BT_CTF_NOTIF_ITER_STATUS_ERROR.
 168          *
 169          * If #BT_CTF_NOTIF_ITER_MEDIUM_STATUS_OK is not returned, the
 170          * values of \p buffer_sz and \p buffer_addr are \em ignored by
 171          * the caller.
 172          *
 173          * @param request_sz    Requested buffer size (bytes)
 174          * @param buffer_addr   Returned buffer address
 175          * @param buffer_sz     Returned buffer's size (bytes)
 176          * @param data          User data
 177          * @returns             Status code (see description above)
 178          */
 179         enum bt_ctf_notif_iter_medium_status (* request_bytes)(
 180                         size_t request_sz, uint8_t **buffer_addr,
 181                         size_t *buffer_sz, void *data);
 182
 183         /**
 184          * Returns a stream instance (weak reference) for the given
 185          * stream class.
 186          *
 187          * This is called after a packet header is read, and the
 188          * corresponding stream class is found by the notification
 189          * iterator.
 190          *
 191          * @param stream_class  Stream class associated to the stream
 192          * @param data          User data
 193          * @returns             Stream instance (weak reference) or
 194          *                      \c NULL on error
 195          */
 196         struct bt_ctf_stream * (* get_stream)(
 197                         struct bt_ctf_stream_class *stream_class, void *data);
 198 };
 199
 200 /** CTF notification iterator. */
 201 struct bt_ctf_notif_iter;
 202
 203 // TODO: Replace by the real thing
 204 enum bt_ctf_notif_iter_notif_type {
 205         BT_CTF_NOTIF_ITER_NOTIF_NEW_PACKET,
 206         BT_CTF_NOTIF_ITER_NOTIF_END_OF_PACKET,
 207         BT_CTF_NOTIF_ITER_NOTIF_EVENT,
 208 };
 209
 210 struct bt_ctf_notif_iter_notif {
 211         enum bt_ctf_notif_iter_notif_type type;
 212 };
 213
 214 struct bt_ctf_notif_iter_notif_new_packet {
 215         struct bt_ctf_notif_iter_notif base;
 216         struct bt_ctf_packet *packet;
 217 };
 218
 219 struct bt_ctf_notif_iter_notif_end_of_packet {
 220         struct bt_ctf_notif_iter_notif base;
 221         struct bt_ctf_packet *packet;
 222 };
 223
 224 struct bt_ctf_notif_iter_notif_event {
 225         struct bt_ctf_notif_iter_notif base;
 226         struct bt_ctf_event *event;
 227 };
 228
 229 void bt_ctf_notif_iter_notif_destroy(void *notif);
 230
 231 /**
 232  * Creates a CTF notification iterator.
 233  *
 234  * Upon successful completion, the reference count of \p trace is
 235  * incremented.
 236  *
 237  * @param trace                 Trace to read
 238  * @param max_request_sz        Maximum buffer size, in bytes, to
 239  *                              request to
 240  *                              bt_ctf_notif_iter_medium_ops::request_bytes()
 241  *                              at a time
 242  * @param medops                Medium operations
 243  * @param medops_data           User data (passed to medium operations)
 244  * @param err_stream            Error stream (can be \c NULL to disable)
 245  * @returns                     New CTF notification iterator on
 246  *                              success, or \c NULL on error
 247  */
 248 struct bt_ctf_notif_iter *bt_ctf_notif_iter_create(struct bt_ctf_trace *trace,
 249         size_t max_request_sz, struct bt_ctf_notif_iter_medium_ops medops,
 250         void *medops_data, FILE *err_stream);
 251
 252 /**
 253  * Destroys a CTF notification iterator, freeing all internal resources.
 254  *
 255  * The registered trace's reference count is decremented.
 256  *
 257  * @param notif_iter            CTF notification iterator
 258  */
 259 void bt_ctf_notif_iter_destroy(struct bt_ctf_notif_iter *notif_iter);
 260
 261 /**
 262  * Resets the internal state of a CTF notification iterator.
 263  *
 264  * This function can be used when it is desired to seek to the beginning
 265  * of another packet. It is expected that the next call to
 266  * bt_ctf_notif_iter_medium_ops::request_bytes() made by this
 267  * notification iterator will return the \em first bytes of a \em
 268  * packet.
 269  *
 270  * @param notif_iter            CTF notification iterator
 271  */
 272 void bt_ctf_notif_iter_reset(struct bt_ctf_notif_iter *notif_iter);
 273
 274 /**
 275  * Returns the next notification from a CTF notification iterator.
 276  *
 277  * Upon successful completion, #BT_CTF_NOTIF_ITER_STATUS_OK is
 278  * returned, and the next notification is written to \p notif.
 279  * In this case, the caller is responsible for calling
 280  * bt_notification_put() on the returned notification.
 281  *
 282  * If this function returns #BT_CTF_NOTIF_ITER_STATUS_AGAIN, the caller
 283  * should make sure that data becomes available to its medium, and
 284  * call this function again, until another status is returned.
 285  *
 286  * @param notif_iter            CTF notification iterator
 287  * @param notification          Returned notification if the function's
 288  *                              return value is #BT_CTF_NOTIF_ITER_STATUS_OK
 289  * @returns                     One of #bt_ctf_notif_iter_status values
 290  */
 291 enum bt_ctf_notif_iter_status bt_ctf_notif_iter_get_next_notification(
 292                 struct bt_ctf_notif_iter *notif_iter,
 293                 struct bt_ctf_notif_iter_notif **notification);
 294
 295 #endif /* CTF_NOTIF_ITER_H */