git.gag.com Git - debian/amanda/blob - device-src/xfer-source-recovery.c

   1 /*
   2  * Amanda, The Advanced Maryland Automatic Network Disk Archiver
   3  * Copyright (c) 2009, 2010 Zmanda, Inc.  All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published
   7  * by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  17  *
  18  * Contact information: Zmanda Inc., 465 S. Mathilda Ave., Suite 300
  19  * Sunnyvale, CA 94085, USA, or: http://www.zmanda.com
  20  */
  21
  22 #include "amanda.h"
  23 #include "amxfer.h"
  24 #include "device.h"
  25 #include "property.h"
  26 #include "xfer-device.h"
  27 #include "arglist.h"
  28 #include "conffile.h"
  29
  30 /*
  31  * Class declaration
  32  *
  33  * This declaration is entirely private; nothing but xfer_source_recovery() references
  34  * it directly.
  35  */
  36
  37 GType xfer_source_recovery_get_type(void);
  38 #define XFER_SOURCE_RECOVERY_TYPE (xfer_source_recovery_get_type())
  39 #define XFER_SOURCE_RECOVERY(obj) G_TYPE_CHECK_INSTANCE_CAST((obj), xfer_source_recovery_get_type(), XferSourceRecovery)
  40 #define XFER_SOURCE_RECOVERY_CONST(obj) G_TYPE_CHECK_INSTANCE_CAST((obj), xfer_source_recovery_get_type(), XferSourceRecovery const)
  41 #define XFER_SOURCE_RECOVERY_CLASS(klass) G_TYPE_CHECK_CLASS_CAST((klass), xfer_source_recovery_get_type(), XferSourceRecoveryClass)
  42 #define IS_XFER_SOURCE_RECOVERY(obj) G_TYPE_CHECK_INSTANCE_TYPE((obj), xfer_source_recovery_get_type ())
  43 #define XFER_SOURCE_RECOVERY_GET_CLASS(obj) G_TYPE_INSTANCE_GET_CLASS((obj), xfer_source_recovery_get_type(), XferSourceRecoveryClass)
  44
  45 static GObjectClass *parent_class = NULL;
  46
  47 /*
  48  * Main object structure
  49  */
  50
  51 typedef struct XferSourceRecovery {
  52     XferElement __parent__;
  53
  54     /* thread for monitoring directtcp transfers */
  55     GThread *thread;
  56
  57     /* this mutex in this condition variable governs all variables below */
  58     GCond *start_part_cond;
  59     GMutex *start_part_mutex;
  60
  61     /* is this device currently paused and awaiting a new part? */
  62     gboolean paused;
  63
  64     /* device to read from (refcounted) */
  65     Device *device;
  66
  67     /* TRUE if use_device found the device unsuitable; this makes start_part
  68      * a no-op, allowing the cancellation to be handled normally */
  69     gboolean device_bad;
  70
  71     /* directtcp connection (only valid after XMSG_READY) */
  72     DirectTCPConnection *conn;
  73     gboolean listen_ok;
  74
  75     /* and the block size for that device (reset to zero at the start of each
  76      * part) */
  77     size_t block_size;
  78
  79     /* part size (potentially including any zero-padding from the
  80      * device) */
  81     guint64 part_size;
  82
  83     /* timer for the duration; NULL while paused or cancelled */
  84     GTimer *part_timer;
  85
  86     gint64   size;
  87 } XferSourceRecovery;
  88
  89 /*
  90  * Class definition
  91  */
  92
  93 typedef struct {
  94     XferElementClass __parent__;
  95
  96     /* start reading the part at which DEVICE is positioned, sending an
  97      * XMSG_PART_DONE when the part has been read */
  98     void (*start_part)(XferSourceRecovery *self, Device *device);
  99
 100     /* use the given device, much like the same method for xfer-dest-taper */
 101     void (*use_device)(XferSourceRecovery *self, Device *device);
 102 } XferSourceRecoveryClass;
 103
 104 /*
 105  * Debug Logging
 106  */
 107
 108 #define DBG(LEVEL, ...) if (debug_recovery >= LEVEL) { _xsr_dbg(__VA_ARGS__); }
 109 static void
 110 _xsr_dbg(const char *fmt, ...)
 111 {
 112     va_list argp;
 113     char msg[1024];
 114
 115     arglist_start(argp, fmt);
 116     g_vsnprintf(msg, sizeof(msg), fmt, argp);
 117     arglist_end(argp);
 118     g_debug("XSR thd-%p: %s", g_thread_self(), msg);
 119 }
 120
 121 /*
 122  * Implementation
 123  */
 124
 125 /* common code for both directtcp_listen_thread and directtcp_connect_thread;
 126  * this is called after self->conn is filled in and carries out the data
 127  * transfer over that connection.  NOTE: start_part_mutex is HELD when this
 128  * function begins */
 129 static gpointer
 130 directtcp_common_thread(
 131         XferSourceRecovery *self)
 132 {
 133     XferElement *elt = XFER_ELEMENT(self);
 134     char *errmsg = NULL;
 135
 136     /* send XMSG_READY to indicate it's OK to call start_part now */
 137     DBG(2, "sending XMSG_READY");
 138     xfer_queue_message(elt->xfer, xmsg_new(elt, XMSG_READY, 0));
 139
 140     /* now we sit around waiting for signals to write a part */
 141     while (1) {
 142         guint64 actual_size;
 143         XMsg *msg;
 144
 145         while (self->paused && !elt->cancelled) {
 146             DBG(9, "waiting to be un-paused");
 147             g_cond_wait(self->start_part_cond, self->start_part_mutex);
 148         }
 149         DBG(9, "done waiting");
 150
 151         if (elt->cancelled) {
 152             g_mutex_unlock(self->start_part_mutex);
 153             goto close_conn_and_send_done;
 154         }
 155
 156         /* if the device is NULL, we're done */
 157         if (!self->device)
 158             break;
 159
 160         /* read the part */
 161         self->part_timer = g_timer_new();
 162
 163         while (1) {
 164             DBG(2, "reading part from %s", self->device->device_name);
 165             if (!device_read_to_connection(self->device, G_MAXUINT64, &actual_size)) {
 166                 xfer_cancel_with_error(elt, _("error reading from device: %s"),
 167                     device_error_or_status(self->device));
 168                 g_mutex_unlock(self->start_part_mutex);
 169                 goto close_conn_and_send_done;
 170             }
 171
 172             /* break on EOF; otherwise do another read_to_connection */
 173             if (self->device->is_eof) {
 174                 break;
 175             }
 176         }
 177         DBG(2, "done reading part; sending XMSG_PART_DONE");
 178
 179         /* the device has signalled EOF (really end-of-part), so clean up instance
 180          * variables and report the EOP to the caller in the form of an xmsg */
 181         msg = xmsg_new(XFER_ELEMENT(self), XMSG_PART_DONE, 0);
 182         msg->size = actual_size;
 183         msg->duration = g_timer_elapsed(self->part_timer, NULL);
 184         msg->partnum = 0;
 185         msg->fileno = self->device->file;
 186         msg->successful = TRUE;
 187         msg->eof = FALSE;
 188
 189         self->paused = TRUE;
 190         g_object_unref(self->device);
 191         self->device = NULL;
 192         self->part_size = 0;
 193         self->block_size = 0;
 194         g_timer_destroy(self->part_timer);
 195         self->part_timer = NULL;
 196
 197         xfer_queue_message(elt->xfer, msg);
 198     }
 199     g_mutex_unlock(self->start_part_mutex);
 200
 201 close_conn_and_send_done:
 202     if (self->conn) {
 203         errmsg = directtcp_connection_close(self->conn);
 204         g_object_unref(self->conn);
 205         self->conn = NULL;
 206         if (errmsg) {
 207             xfer_cancel_with_error(elt, _("error closing DirectTCP connection: %s"), errmsg);
 208             wait_until_xfer_cancelled(elt->xfer);
 209         }
 210     }
 211
 212     xfer_queue_message(elt->xfer, xmsg_new(elt, XMSG_DONE, 0));
 213
 214     return NULL;
 215 }
 216
 217 static gpointer
 218 directtcp_connect_thread(
 219         gpointer data)
 220 {
 221     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(data);
 222     XferElement *elt = XFER_ELEMENT(self);
 223
 224     DBG(1, "(this is directtcp_connect_thread)")
 225
 226     /* first, we need to accept the incoming connection; we do this while
 227      * holding the start_part_mutex, so that a part doesn't get started until
 228      * we're finished with the device */
 229     g_mutex_lock(self->start_part_mutex);
 230
 231     if (elt->cancelled) {
 232         g_mutex_unlock(self->start_part_mutex);
 233         goto send_done;
 234     }
 235
 236     g_assert(self->device != NULL); /* have a device */
 237     g_assert(elt->output_listen_addrs != NULL); /* listening on it */
 238     g_assert(self->listen_ok);
 239
 240     DBG(2, "accepting DirectTCP connection on device %s", self->device->device_name);
 241     if (!device_accept(self->device, &self->conn, NULL, NULL)) {
 242         xfer_cancel_with_error(elt,
 243             _("error accepting DirectTCP connection: %s"),
 244             device_error_or_status(self->device));
 245         g_mutex_unlock(self->start_part_mutex);
 246         wait_until_xfer_cancelled(elt->xfer);
 247         goto send_done;
 248     }
 249     DBG(2, "DirectTCP connection accepted");
 250
 251     return directtcp_common_thread(self);
 252
 253 send_done:
 254     xfer_queue_message(elt->xfer, xmsg_new(elt, XMSG_DONE, 0));
 255     return NULL;
 256 }
 257
 258 static gpointer
 259 directtcp_listen_thread(
 260         gpointer data)
 261 {
 262     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(data);
 263     XferElement *elt = XFER_ELEMENT(self);
 264
 265     DBG(1, "(this is directtcp_listen_thread)");
 266
 267     /* we need to make an outgoing connection to downstream; we do this while
 268      * holding the start_part_mutex, so that a part doesn't get started until
 269      * we're finished with the device */
 270     g_mutex_lock(self->start_part_mutex);
 271
 272     if (elt->cancelled) {
 273         g_mutex_unlock(self->start_part_mutex);
 274         goto send_done;
 275     }
 276
 277     g_assert(self->device != NULL); /* have a device */
 278     g_assert(elt->downstream->input_listen_addrs != NULL); /* downstream listening */
 279
 280     DBG(2, "making DirectTCP connection on device %s", self->device->device_name);
 281     if (!device_connect(self->device, FALSE, elt->downstream->input_listen_addrs,
 282                         &self->conn, NULL, NULL)) {
 283         xfer_cancel_with_error(elt,
 284             _("error making DirectTCP connection: %s"),
 285             device_error_or_status(self->device));
 286         g_mutex_unlock(self->start_part_mutex);
 287         wait_until_xfer_cancelled(elt->xfer);
 288         goto send_done;
 289     }
 290     DBG(2, "DirectTCP connect succeeded");
 291
 292     return directtcp_common_thread(self);
 293
 294 send_done:
 295     xfer_queue_message(elt->xfer, xmsg_new(elt, XMSG_DONE, 0));
 296     return NULL;
 297 }
 298
 299 static gboolean
 300 setup_impl(
 301     XferElement *elt)
 302 {
 303     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(elt);
 304
 305     if (elt->output_mech == XFER_MECH_DIRECTTCP_CONNECT) {
 306         g_assert(self->device != NULL);
 307         DBG(2, "listening for DirectTCP connection on device %s", self->device->device_name);
 308         if (!device_listen(self->device, FALSE, &elt->output_listen_addrs)) {
 309             xfer_cancel_with_error(elt,
 310                 _("error listening for DirectTCP connection: %s"),
 311                 device_error_or_status(self->device));
 312             return FALSE;
 313         }
 314         self->listen_ok = TRUE;
 315     } else {
 316         /* no output_listen_addrs for either XFER_MECH_DIRECTTCP_LISTEN or
 317          * XFER_MECH_PULL_BUFFER */
 318         elt->output_listen_addrs = NULL;
 319     }
 320
 321     return TRUE;
 322 }
 323
 324 static gboolean
 325 start_impl(
 326     XferElement *elt)
 327 {
 328     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(elt);
 329
 330     if (elt->output_mech == XFER_MECH_DIRECTTCP_CONNECT) {
 331         g_assert(elt->output_listen_addrs != NULL);
 332         self->thread = g_thread_create(directtcp_connect_thread, (gpointer)self, FALSE, NULL);
 333         return TRUE; /* we'll send XMSG_DONE */
 334     } else if (elt->output_mech == XFER_MECH_DIRECTTCP_LISTEN) {
 335         g_assert(elt->output_listen_addrs == NULL);
 336         self->thread = g_thread_create(directtcp_listen_thread, (gpointer)self, FALSE, NULL);
 337         return TRUE; /* we'll send XMSG_DONE */
 338     } else {
 339         /* nothing to prepare for - we're ready already! */
 340         DBG(2, "not using DirectTCP: sending XMSG_READY immediately");
 341         xfer_queue_message(elt->xfer, xmsg_new(elt, XMSG_READY, 0));
 342
 343         return FALSE; /* we won't send XMSG_DONE */
 344     }
 345 }
 346
 347 static gpointer
 348 pull_buffer_impl(
 349     XferElement *elt,
 350     size_t *size)
 351 {
 352     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(elt);
 353     gpointer buf = NULL;
 354     int result;
 355     int devsize;
 356     XMsg *msg;
 357
 358     g_assert(elt->output_mech == XFER_MECH_PULL_BUFFER);
 359     g_mutex_lock(self->start_part_mutex);
 360
 361     while (1) {
 362         /* make sure we have a device */
 363         while (self->paused && !elt->cancelled)
 364             g_cond_wait(self->start_part_cond, self->start_part_mutex);
 365
 366         /* indicate EOF on an cancel or when there are no more parts */
 367         if (elt->cancelled || !self->device) {
 368             goto error;
 369         }
 370
 371         /* start the timer if this is the first pull_buffer of this part */
 372         if (!self->part_timer) {
 373             DBG(2, "first pull_buffer of new part");
 374             self->part_timer = g_timer_new();
 375         }
 376
 377         /* loop until we read a full block, in case the blocks are larger than
 378          * expected */
 379         if (self->block_size == 0)
 380             self->block_size = (size_t)self->device->block_size;
 381
 382         do {
 383             buf = g_malloc(self->block_size);
 384             devsize = (int)self->block_size;
 385             result = device_read_block(self->device, buf, &devsize);
 386             *size = devsize;
 387
 388             if (result == 0) {
 389                 g_assert(*size > self->block_size);
 390                 self->block_size = devsize;
 391                 amfree(buf);
 392             }
 393         } while (result == 0);
 394
 395         /* if this block was successful, return it */
 396         if (result > 0) {
 397             self->part_size += *size;
 398             break;
 399         }
 400
 401         if (result < 0) {
 402             amfree(buf);
 403
 404             /* if we're not at EOF, it's an error */
 405             if (!self->device->is_eof) {
 406                 xfer_cancel_with_error(elt,
 407                     _("error reading from %s: %s"),
 408                     self->device->device_name,
 409                     device_error_or_status(self->device));
 410                 wait_until_xfer_cancelled(elt->xfer);
 411                 goto error;
 412             }
 413
 414             /* the device has signalled EOF (really end-of-part), so clean up instance
 415              * variables and report the EOP to the caller in the form of an xmsg */
 416             DBG(2, "pull_buffer hit EOF; sending XMSG_PART_DONE");
 417             msg = xmsg_new(XFER_ELEMENT(self), XMSG_PART_DONE, 0);
 418             msg->size = self->part_size;
 419             msg->duration = g_timer_elapsed(self->part_timer, NULL);
 420             msg->partnum = 0;
 421             msg->fileno = self->device->file;
 422             msg->successful = TRUE;
 423             msg->eof = FALSE;
 424
 425             self->paused = TRUE;
 426             g_object_unref(self->device);
 427             self->device = NULL;
 428             self->part_size = 0;
 429             self->block_size = 0;
 430             if (self->part_timer) {
 431                 g_timer_destroy(self->part_timer);
 432                 self->part_timer = NULL;
 433             }
 434
 435             /* don't queue the XMSG_PART_DONE until we've adjusted all of our
 436              * instance variables appropriately */
 437             xfer_queue_message(elt->xfer, msg);
 438         }
 439     }
 440
 441     g_mutex_unlock(self->start_part_mutex);
 442
 443     if (elt->size > 0) {
 444         /* initialize on first pass */
 445         if (self->size == 0)
 446             self->size = elt->size;
 447
 448         if (self->size == -1) {
 449             *size = 0;
 450             amfree(buf);
 451             return NULL;
 452         }
 453
 454         if (*size > (guint64)self->size) {
 455             /* return only self->size bytes */
 456             *size = self->size;
 457             self->size = -1;
 458         } else {
 459             self->size -= *size;
 460         }
 461     }
 462
 463     return buf;
 464 error:
 465     g_mutex_unlock(self->start_part_mutex);
 466     *size = 0;
 467     return NULL;
 468 }
 469
 470 static gboolean
 471 cancel_impl(
 472     XferElement *elt,
 473     gboolean expect_eof G_GNUC_UNUSED)
 474 {
 475     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(elt);
 476     elt->cancelled = TRUE;
 477
 478     /* trigger the condition variable, in case the thread is waiting on it */
 479     g_mutex_lock(self->start_part_mutex);
 480     g_cond_broadcast(self->start_part_cond);
 481     g_mutex_unlock(self->start_part_mutex);
 482
 483     return TRUE;
 484 }
 485
 486 static void
 487 start_part_impl(
 488     XferSourceRecovery *self,
 489     Device *device)
 490 {
 491     g_assert(!device || device->in_file);
 492
 493     DBG(2, "start_part called");
 494
 495     if (self->device_bad) {
 496         /* use_device didn't like the device it got, but the xfer cancellation
 497          * has not completed yet, so do nothing */
 498         return;
 499     }
 500
 501     g_mutex_lock(self->start_part_mutex);
 502
 503     /* make sure we're ready to go */
 504     g_assert(self->paused);
 505     if (XFER_ELEMENT(self)->output_mech == XFER_MECH_DIRECTTCP_CONNECT
 506      || XFER_ELEMENT(self)->output_mech == XFER_MECH_DIRECTTCP_LISTEN) {
 507         g_assert(self->conn != NULL);
 508     }
 509
 510     /* if we already have a device, it should have been given to use_device */
 511     if (device && self->device)
 512         g_assert(self->device == device);
 513
 514     if (self->device)
 515         g_object_unref(self->device);
 516     if (device)
 517         g_object_ref(device);
 518     self->device = device;
 519
 520     self->paused = FALSE;
 521
 522     DBG(2, "triggering condition variable");
 523     g_cond_broadcast(self->start_part_cond);
 524     g_mutex_unlock(self->start_part_mutex);
 525 }
 526
 527 static void
 528 use_device_impl(
 529     XferSourceRecovery *xdtself,
 530     Device *device)
 531 {
 532     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(xdtself);
 533
 534     g_assert(self->paused);
 535
 536     /* short-circuit if nothing is changing */
 537     if (self->device == device)
 538         return;
 539
 540     if (self->device)
 541         g_object_unref(self->device);
 542     self->device = NULL;
 543
 544     /* if we already have a connection, then make this device use it */
 545     if (self->conn) {
 546         if (!device_use_connection(device, self->conn)) {
 547             /* queue up an error for later, and set device_bad.
 548              * start_part will see this and fail silently */
 549             self->device_bad = TRUE;
 550             xfer_cancel_with_error(XFER_ELEMENT(self),
 551                 _("Cannot continue onto new volume: %s"),
 552                 device_error_or_status(device));
 553             return;
 554         }
 555     }
 556
 557     self->device = device;
 558     g_object_ref(device);
 559 }
 560
 561 static xfer_element_mech_pair_t *
 562 get_mech_pairs_impl(
 563     XferElement *elt)
 564 {
 565     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(elt);
 566     static xfer_element_mech_pair_t basic_mech_pairs[] = {
 567         { XFER_MECH_NONE, XFER_MECH_PULL_BUFFER, 1, 0},
 568         { XFER_MECH_NONE, XFER_MECH_NONE, 0, 0},
 569     };
 570     static xfer_element_mech_pair_t directtcp_mech_pairs[] = {
 571         { XFER_MECH_NONE, XFER_MECH_DIRECTTCP_CONNECT, 0, 1},
 572         { XFER_MECH_NONE, XFER_MECH_DIRECTTCP_LISTEN, 0, 1},
 573         /* devices which support DirectTCP are usually not very efficient
 574          * at delivering data via device_read_block, so this counts an extra
 575          * byte operation in the cost metrics (2 here vs. 1 in basic_mech_pairs).
 576          * This is a hack, but it will do for now. */
 577         { XFER_MECH_NONE, XFER_MECH_PULL_BUFFER, 2, 0},
 578         { XFER_MECH_NONE, XFER_MECH_NONE, 0, 0},
 579     };
 580
 581     return device_directtcp_supported(self->device)?
 582         directtcp_mech_pairs : basic_mech_pairs;
 583 }
 584
 585 static void
 586 finalize_impl(
 587     GObject * obj_self)
 588 {
 589     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(obj_self);
 590
 591     if (self->conn)
 592         g_object_unref(self->conn);
 593     if (self->device)
 594         g_object_unref(self->device);
 595
 596     g_cond_free(self->start_part_cond);
 597     g_mutex_free(self->start_part_mutex);
 598 }
 599
 600 static void
 601 instance_init(
 602     XferElement *elt)
 603 {
 604     XferSourceRecovery *self = XFER_SOURCE_RECOVERY(elt);
 605
 606     self->paused = TRUE;
 607     self->start_part_cond = g_cond_new();
 608     self->start_part_mutex = g_mutex_new();
 609 }
 610
 611 static void
 612 class_init(
 613     XferSourceRecoveryClass * xsr_klass)
 614 {
 615     XferElementClass *klass = XFER_ELEMENT_CLASS(xsr_klass);
 616     GObjectClass *gobject_klass = G_OBJECT_CLASS(xsr_klass);
 617
 618     klass->pull_buffer = pull_buffer_impl;
 619     klass->cancel = cancel_impl;
 620     klass->start = start_impl;
 621     klass->setup = setup_impl;
 622     klass->get_mech_pairs = get_mech_pairs_impl;
 623
 624     klass->perl_class = "Amanda::Xfer::Source::Recovery";
 625     klass->mech_pairs = NULL; /* see get_mech_pairs_impl, above */
 626
 627     xsr_klass->start_part = start_part_impl;
 628     xsr_klass->use_device = use_device_impl;
 629
 630     gobject_klass->finalize = finalize_impl;
 631
 632     parent_class = g_type_class_peek_parent(xsr_klass);
 633 }
 634
 635 GType
 636 xfer_source_recovery_get_type (void)
 637 {
 638     static GType type = 0;
 639
 640     if G_UNLIKELY(type == 0) {
 641         static const GTypeInfo info = {
 642             sizeof (XferSourceRecoveryClass),
 643             (GBaseInitFunc) NULL,
 644             (GBaseFinalizeFunc) NULL,
 645             (GClassInitFunc) class_init,
 646             (GClassFinalizeFunc) NULL,
 647             NULL /* class_data */,
 648             sizeof (XferSourceRecovery),
 649             0 /* n_preallocs */,
 650             (GInstanceInitFunc) instance_init,
 651             NULL
 652         };
 653
 654         type = g_type_register_static (XFER_ELEMENT_TYPE, "XferSourceRecovery", &info, 0);
 655     }
 656
 657     return type;
 658 }
 659
 660 /*
 661  * Public methods and stubs
 662  */
 663
 664 void
 665 xfer_source_recovery_start_part(
 666     XferElement *elt,
 667     Device *device)
 668 {
 669     XferSourceRecoveryClass *klass;
 670     g_assert(IS_XFER_SOURCE_RECOVERY(elt));
 671
 672     klass = XFER_SOURCE_RECOVERY_GET_CLASS(elt);
 673     klass->start_part(XFER_SOURCE_RECOVERY(elt), device);
 674 }
 675
 676 /* create an element of this class; prototype is in xfer-device.h */
 677 XferElement *
 678 xfer_source_recovery(Device *first_device)
 679 {
 680     XferSourceRecovery *self = (XferSourceRecovery *)g_object_new(XFER_SOURCE_RECOVERY_TYPE, NULL);
 681     XferElement *elt = XFER_ELEMENT(self);
 682
 683     g_assert(first_device != NULL);
 684     g_object_ref(first_device);
 685     self->device = first_device;
 686
 687     return elt;
 688 }
 689
 690 void
 691 xfer_source_recovery_use_device(
 692     XferElement *elt,
 693     Device *device)
 694 {
 695     XferSourceRecoveryClass *klass;
 696     g_assert(IS_XFER_SOURCE_RECOVERY(elt));
 697
 698     klass = XFER_SOURCE_RECOVERY_GET_CLASS(elt);
 699     klass->use_device(XFER_SOURCE_RECOVERY(elt), device);
 700 }