aboutsummaryrefslogtreecommitdiffstats
path: root/mail/mail-threads.c
blob: 6e17761b2febd1ec4cb2ac4da55988f4b08ea198 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */

/*
 * Author :
 *  Peter Williams (peterw@helixcode.com)
 *
 *  Copyright 2000, Helix Code, Inc. (http://www.helixcode.com)
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Street #330, Boston, MA 02111-1307, USA.
 *
 */

#include <config.h>

#include <string.h>
#include <glib.h>

#include "folder-browser-factory.h"

#include "camel/camel-object.h"
#include "mail.h"
#include "mail-threads.h"

#define DEBUG(p) g_print p

/**
 * A function and its userdata
 **/

typedef struct closure_s
{
    gpointer in_data;
    gboolean free_in_data;
    gpointer op_data;
    const mail_operation_spec *spec;
    CamelException *ex;
    gchar *infinitive;
    gchar *gerund;
}
closure_t;

/**
 * A command issued through the compipe
 **/

typedef struct com_msg_s
{
    enum com_msg_type_e { 
        STARTING, 

#if 0
        PERCENTAGE, 
        HIDE_PBAR, 
        SHOW_PBAR, 
#endif

        MESSAGE, 
        PASSWORD,
        ERROR, 
        FORWARD_EVENT,
        FINISHED
    } type;

    gfloat percentage;
    gchar *message;

    closure_t *clur;

    /* Password stuff */
    gchar **reply;
    gboolean secret;
    gboolean *success;

    /* Event stuff */
    CamelObjectEventHookFunc event_hook;
    CamelObject *event_obj;
    gpointer event_event_data;
    gpointer event_user_data;
}
com_msg_t;

/**
 * Stuff needed for blocking
 **/

typedef struct block_info_s {
    GMutex *mutex;
    GCond *cond;
    gboolean val;
} block_info_t;

#define BLOCK_INFO_INIT { NULL, NULL, FALSE }

/**
 * @dispatch_thread_started: gboolean that tells us whether
 * the dispatch thread has been launched.
 **/

static gboolean dispatch_thread_started = FALSE;

/** 
 * @queue_len : the number of operations pending
 * and being executed.
 *
 * Because camel is not thread-safe we work
 * with the restriction that more than one mailbox
 * cannot be accessed at once. Thus we cannot
 * concurrently check mail and move messages, etc.
 **/

static gint queue_len = 0;

/**
 * @main_compipe: The pipe through which the dispatcher communicates
 * with the main thread for GTK+ calls
 *
 * @chan_reader: the GIOChannel that reads our pipe
 *
 * @MAIN_READER: the fd in our main pipe that.... reads!
 * @MAIN_WRITER: the fd in our main pipe that.... writes!
 */

#define MAIN_READER main_compipe[0]
#define MAIN_WRITER main_compipe[1]
#define DISPATCH_READER dispatch_compipe[0]
#define DISPATCH_WRITER dispatch_compipe[1]

static int main_compipe[2] = { -1, -1 };
static int dispatch_compipe[2] = { -1, -1 };

GIOChannel *chan_reader = NULL;

/**
 * @modal_block: a condition maintained so that the
 * calling thread (the dispatch thread) blocks correctly
 * until the user has responded to some kind of modal
 * dialog boxy thing.
 */

static block_info_t modal_block = BLOCK_INFO_INIT;

/**
 * @finish_block: A condition so that the dispatch thread
 * blocks until the main thread has finished the cleanup.
 **/

static block_info_t finish_block = BLOCK_INFO_INIT;

/**
 * @current_message: The current message for the status bar.
 * @busy_status: Whether we are currently busy doing some async operation,
 * for status bar purposes.
 */

static char *current_message = NULL;
static gboolean busy = FALSE;

/**
 * Static prototypes
 **/

static void ui_set_busy (void);
static void ui_unset_busy (void);
static void ui_set_message (const char *message);
static void ui_unset_message (void);

static void block_prepare (block_info_t *info);
static void block_wait (block_info_t *info);
static void block_hold (block_info_t *info);
static void block_release (block_info_t *info);

static void *dispatch (void * data);
static void check_dispatcher (void);
static void check_compipes (void);
static gboolean read_msg (GIOChannel * source, GIOCondition condition,
              gpointer userdata);

static void show_error (com_msg_t * msg);

static void get_password (com_msg_t * msg);
static void get_password_cb (gchar * string, gpointer data);

static void cleanup_op (com_msg_t * msg);

static closure_t *new_closure (const mail_operation_spec * spec, gpointer input,
                   gboolean free_in_data);
static void free_closure (closure_t *clur);

/* Pthread code */
/* FIXME: support other thread types!!!! */

#ifdef G_THREADS_IMPL_POSIX

#include <pthread.h>

/**
 * @dispatch_thread: the pthread_t (when using pthreads, of
 * course) representing our dispatcher routine. Never used
 * except to make pthread_create happy
 **/

static pthread_t dispatch_thread;

/* FIXME: do we need to set any attributes for our thread? 
 * If so, we need to create a pthread_attr structure and
 * fill it in somewhere. But the defaults should be good
 * enough.
 */

#elif defined( G_THREADS_IMPL_SOLARIS )

#include <thread.h>

static thread_t dispatch_thread;

#else /* no supported thread impl */
void
f (void)
{
    Error_No_supported_thread_implementation_recognized ();
    choke on this;
}
#endif

/**
 * mail_operation_queue:
 * @spec: describes the operation to be performed
 * @input: input data for the operation.
 *
 * Runs a mail operation asynchronously. If no other operation is running,
 * we start another thread and call the callback in that thread. The function
 * can then use the mail_op_ functions to perform limited UI returns, while
 * the main UI is completely unlocked.
 *
 * If an async operation is going on when this function is called again, 
 * it waits for the currently executing operation to finish, then
 * executes the callback function in another thread.
 *
 * Returns TRUE on success, FALSE on some sort of queueing error.
 **/

gboolean
mail_operation_queue (const mail_operation_spec * spec, gpointer input,
              gboolean free_in_data)
{
    closure_t *clur;

    g_assert (spec);

    clur = new_closure (spec, input, free_in_data);

    if (spec->setup)
        (spec->setup) (clur->in_data, clur->op_data, clur->ex);

    if (camel_exception_is_set (clur->ex)) {
        if (clur->ex->id != CAMEL_EXCEPTION_USER_CANCEL) {
            GtkWidget *err_dialog;
            gchar *msg;

            msg =
                g_strdup_printf
                ("Error while preparing to %s:\n" "%s",
                 clur->infinitive,
                 camel_exception_get_description (clur->ex));
            err_dialog = gnome_error_dialog (msg);
            g_free (msg);
            gnome_dialog_set_close (GNOME_DIALOG (err_dialog),
                        TRUE);
            GDK_THREADS_ENTER ();
            gnome_dialog_run_and_close (GNOME_DIALOG (err_dialog));
            GDK_THREADS_LEAVE ();
            /*gtk_widget_destroy (err_dialog); */
            /*gtk_widget_show (GTK_WIDGET (err_dialog));*/

            g_warning ("Setup failed for `%s': %s",
                   clur->infinitive,
                   camel_exception_get_description (clur->
                                    ex));
        }

        free_closure (clur);
        return FALSE;
    }

    if (queue_len == 0) {
        check_compipes ();
        check_dispatcher ();
    } /* else add self to queue */

    write (DISPATCH_WRITER, clur, sizeof (closure_t));
    queue_len++;
    return TRUE;
}

#if 0
/**
 * mail_op_set_percentage:
 * @percentage: the percentage that will be displayed in the progress bar
 *
 * Set the percentage of the progress bar for the currently executing operation.
 * Threadsafe for, nay, intended to be called by, the dispatching thread.
 **/

void
mail_op_set_percentage (gfloat percentage)
{
    com_msg_t msg;

    msg.type = PERCENTAGE;
    msg.percentage = percentage;
    write (MAIN_WRITER, &msg, sizeof (msg));
}

/**
 * mail_op_hide_progressbar:
 *
 * Hide the progress bar in the status box
 * Threadsafe for, nay, intended to be called by, the dispatching thread.
 **/

void
mail_op_hide_progressbar (void)
{
    com_msg_t msg;

    msg.type = HIDE_PBAR;
    write (MAIN_WRITER, &msg, sizeof (msg));
}

/**
 * mail_op_show_progressbar:
 *
 * Show the progress bar in the status box
 * Threadsafe for, nay, intended to be called by, the dispatching thread.
 **/

void
mail_op_show_progressbar (void)
{
    com_msg_t msg;

    msg.type = SHOW_PBAR;
    write (MAIN_WRITER, &msg, sizeof (msg));
}

#endif

/**
 * mail_op_set_message:
 * @fmt: printf-style format string for the message
 * @...: arguments to the format string
 *
 * Set the message displayed above the progress bar for the currently
 * executing operation.
 * Threadsafe for, nay, intended to be called by, the dispatching thread.
 **/

void
mail_op_set_message (gchar * fmt, ...)
{
    com_msg_t msg;
    va_list val;

    va_start (val, fmt);
    msg.type = MESSAGE;
    msg.message = g_strdup_vprintf (fmt, val);
    va_end (val);

    write (MAIN_WRITER, &msg, sizeof (msg));
}

/**
 * mail_op_get_password:
 * @prompt: the question put to the user
 * @secret: whether the dialog box shold print stars when the user types
 * @dest: where to store the reply
 *
 * Asks the user for a password (or string entry in general). Waits for
 * the user's response. On success, returns TRUE and @dest contains the
 * response. On failure, returns FALSE and @dest contains the error
 * message.
 **/

gboolean
mail_op_get_password (gchar * prompt, gboolean secret, gchar ** dest)
{
    com_msg_t msg;
    gboolean result;

    msg.type = PASSWORD;
    msg.secret = secret;
    msg.message = prompt;
    msg.reply = dest;
    msg.success = &result;

    (*dest) = NULL;

    block_prepare (&modal_block);
    write (MAIN_WRITER, &msg, sizeof (msg));
    block_wait (&modal_block);

    return result;
}

/**
 * mail_op_error:
 * @fmt: printf-style format string for the error
 * @...: arguments to the format string
 *
 * Opens an error dialog for the currently executing operation.
 * Threadsafe for, nay, intended to be called by, the dispatching thread.
 **/

void
mail_op_error (gchar * fmt, ...)
{
    com_msg_t msg;
    va_list val;

    va_start (val, fmt);
    msg.type = ERROR;
    msg.message = g_strdup_vprintf (fmt, val);
    va_end (val);

    block_prepare (&modal_block);
    write (MAIN_WRITER, &msg, sizeof (msg));
    block_wait (&modal_block);
}

/**
 * mail_op_forward_event:
 *
 * Communicate a camel event over to the main thread.
 **/

void
mail_op_forward_event (CamelObjectEventHookFunc func, CamelObject *o, 
               gpointer event_data, gpointer user_data)
{
    com_msg_t msg;

    msg.type = FORWARD_EVENT;
    msg.event_hook = func;
    msg.event_obj = o;
    msg.event_event_data = event_data;
    msg.event_user_data = user_data;
    write (MAIN_WRITER, &msg, sizeof (msg));
}
/**
 * mail_operation_wait_for_finish:
 *
 * Waits for the currently executing async operations
 * to finish executing
 */

void
mail_operation_wait_for_finish (void)
{
    while (queue_len)
        gtk_main_iteration ();
    /* Sigh. Otherwise we deadlock upon exit. */
    GDK_THREADS_LEAVE ();
}

/**
 * mail_operations_are_executing:
 *
 * Returns TRUE if operations are being executed asynchronously
 * when called, FALSE if not.
 **/

gboolean
mail_operations_are_executing (void)
{
    return (queue_len > 0);
}

/**
 * mail_operations_terminate:
 *
 * Let the operations finish then terminate the dispatch thread
 **/

void
mail_operations_terminate (void)
{
    closure_t clur;

    mail_operation_wait_for_finish();

    memset (&clur, 0, sizeof (closure_t));
    clur.spec = NULL;

    write (DISPATCH_WRITER, &clur, sizeof (closure_t));
}

void
mail_operations_get_status (int *busy_return,
                const char **message_return)
{
    *busy_return = busy;
    *message_return = current_message;
}

/* ** Static functions **************************************************** */

static void check_dispatcher (void)
{
    int res;

    if (dispatch_thread_started)
        return;

#if defined( G_THREADS_IMPL_POSIX )
    res = pthread_create (&dispatch_thread, NULL,
                  (void *) &dispatch, NULL);
#elif defined( G_THREADS_IMPL_SOLARIS )
    res = thr_create (NULL, 0, (void *) &dispatch, NULL, 0, &dispatch_thread);
#else /* no known impl */
    Error_No_thread_create_implementation ();
    choke on this;
#endif
    if (res != 0) {
        g_warning ("Error launching dispatch thread!");
        /* FIXME: more error handling */
    } else
        dispatch_thread_started = TRUE;
}

/**
 * check_compipes:
 *
 * Check and see if our pipe has been opened and open
 * it if necessary.
 **/

static void
check_compipes (void)
{
    if (MAIN_READER < 0) {
        if (pipe (main_compipe) < 0) {
            g_warning ("Call to pipe(2) failed!");

            /* FIXME: better error handling. How do we react? */
            return;
        }
        
        chan_reader = g_io_channel_unix_new (MAIN_READER);
        g_io_add_watch (chan_reader, G_IO_IN, read_msg, NULL);
    }

    if (DISPATCH_READER < 0) {
        if (pipe (dispatch_compipe) < 0) {
            g_warning ("Call to pipe(2) failed!");

            /* FIXME: better error handling. How do we react? */
            return;
        }
    }
}

/**
 * dispatch:
 * @clur: The operation to execute and its parameters
 *
 * Start a thread that executes the closure and exit
 * it when done.
 */

static void *
dispatch (void *unused)
{
    size_t len;
    closure_t *clur;
    com_msg_t msg;

    /* Let the compipes be created */
    sleep (1);

    while (1) {
        clur = g_new (closure_t, 1);
        len = read (DISPATCH_READER, clur, sizeof (closure_t));

        if (len <= 0)
            break;

        if (len != sizeof (closure_t)) {
            g_warning ("dispatcher: Didn't read full message!");
            continue;
        }

        if (clur->spec == NULL)
            break;

        msg.type = STARTING;
        msg.message = g_strdup (clur->gerund);
        write (MAIN_WRITER, &msg, sizeof (msg));

        (clur->spec->callback) (clur->in_data, clur->op_data, clur->ex);

        if (camel_exception_is_set (clur->ex)) {
            if (clur->ex->id != CAMEL_EXCEPTION_USER_CANCEL) {
                g_warning ("Callback failed for `%s': %s",
                       clur->infinitive,
                       camel_exception_get_description (clur->
                                        ex));
                mail_op_error ("Error while `%s':\n" "%s",
                           clur->gerund,
                           camel_exception_get_description (clur->
                                        ex));
            }
        }

        msg.type = FINISHED;
        msg.clur = clur;

        /* Wait for the cleanup to finish before starting our next op */
        block_prepare (&finish_block);
        write (MAIN_WRITER, &msg, sizeof (msg));
        block_wait (&finish_block);
    }

#ifdef G_THREADS_IMPL_POSIX
    pthread_exit (0);
#elif defined( G_THREADS_IMPL_SOLARIS )
    thr_exit (NULL);
#else /* no known impl */
    Error_No_thread_exit_implemented ();
    choke on this;
#endif
    return NULL;
    /*NOTREACHED*/
}

/**
 * read_msg:
 * @source: the channel that has data to read
 * @condition: the reason we were called
 * @userdata: unused
 *
 * A message has been recieved on our pipe; perform the appropriate 
 * action.
 **/

static gboolean
read_msg (GIOChannel * source, GIOCondition condition, gpointer userdata)
{
    com_msg_t *msg;
    guint size;

    msg = g_new0 (com_msg_t, 1);

    g_io_channel_read (source, (gchar *) msg,
               sizeof (com_msg_t) / sizeof (gchar), &size);

    if (size != sizeof (com_msg_t)) {
        g_warning (_("Incomplete message written on pipe!"));
        msg->type = ERROR;
        msg->message =
            g_strdup (_
                  ("Error reading commands from dispatching thread."));
    }

    /* This is very important, though I'm not quite sure why
     * it is as we are in the main thread right now.
     */

    GDK_THREADS_ENTER ();

    switch (msg->type) {
    case STARTING:
        DEBUG (("*** Message -- STARTING %s\n", msg->message));
        ui_set_message (msg->message);
        ui_set_busy ();
        g_free (msg->message);
        break;
#if 0
    case PERCENTAGE:
        DEBUG (("*** Message -- PERCENTAGE\n"));
        g_warning ("PERCENTAGE operation unsupported");
        break;
    case HIDE_PBAR:
        DEBUG (("*** Message -- HIDE_PBAR\n"));
        g_warning ("HIDE_PBAR operation unsupported");
        break;
    case SHOW_PBAR:
        DEBUG (("*** Message -- SHOW_PBAR\n"));
        g_warning ("HIDE_PBAR operation unsupported");
        break;
#endif

    case MESSAGE:
        DEBUG (("*** Message -- MESSAGE\n"));
        ui_set_message (msg->message);
        g_free (msg->message);
        break;

    case PASSWORD:
        DEBUG (("*** Message -- PASSWORD\n"));
        g_assert (msg->reply);
        g_assert (msg->success);
        get_password (msg);
        break;

    case ERROR:
        DEBUG (("*** Message -- ERROR\n"));
        show_error (msg);
        break;

        /* Don't fall through; dispatch_func does the FINISHED
         * call for us 
         */

    case FORWARD_EVENT:
        DEBUG (("*** Message -- FORWARD_EVENT %p\n", msg->event_hook));
        g_assert (msg->event_hook);
        (msg->event_hook) (msg->event_obj, msg->event_event_data, msg->event_user_data);
        break;

    case FINISHED:
        DEBUG (("*** Message -- FINISH %s\n", msg->clur->gerund));
        cleanup_op (msg);
        break;

    default:
        g_warning (_("Corrupted message from dispatching thread?"));
        break;
    }

    GDK_THREADS_LEAVE ();
    g_free (msg);
    return TRUE;
}

/**
 * cleanup_op:
 *
 * Cleanup after a finished operation
 **/

static void
cleanup_op (com_msg_t * msg)
{
    block_hold (&finish_block);

    /* Run the cleanup */

    if (msg->clur->spec->cleanup)
        (msg->clur->spec->cleanup) (msg->clur->in_data,
                        msg->clur->op_data,
                        msg->clur->ex);
    
    /* Tell the dispatch thread that it can start
     * the next operation */

    block_release (&finish_block);

    /* Print an exception if the cleanup caused one */

    if (camel_exception_is_set (msg->clur->ex) &&
        msg->clur->ex->id != CAMEL_EXCEPTION_USER_CANCEL) {
        g_warning ("Error on cleanup of `%s': %s",
               msg->clur->infinitive,
               camel_exception_get_description (msg->clur->ex));
    }

    free_closure (msg->clur);
    queue_len--;

    ui_unset_busy ();
    ui_unset_message ();
}

/**
 * show_error:
 *
 * Show the error dialog and wait for user OK
 **/

static void
show_error (com_msg_t * msg)
{
    GtkWidget *err_dialog;

    /* Create the dialog */

    err_dialog = gnome_error_dialog (msg->message);
    g_free (msg->message);

    /* Stop the other thread until the user reacts */

    ui_unset_busy ();
    block_hold (&modal_block);

    /* Show the dialog. */

    GDK_THREADS_ENTER ();
    gnome_dialog_run_and_close (GNOME_DIALOG (err_dialog));
    GDK_THREADS_LEAVE ();

    /* Allow the other thread to proceed */

    block_release (&modal_block);
    ui_set_busy ();
}

/**
 * get_password:
 *
 * Ask for a password and put the answer in *(msg->reply)
 **/

static void
get_password (com_msg_t * msg)
{
    GtkWidget *dialog;
    int button;

    /* Create the dialog */

    dialog = gnome_request_dialog (msg->secret, msg->message, NULL,
                       0, get_password_cb, msg, NULL);

    /* Stop the other thread */

    ui_unset_busy ();
    block_hold (&modal_block);

    /* Show the dialog (or report an error) */

    if (dialog == NULL) {
        *(msg->success) = FALSE;
        *(msg->reply) = g_strdup (_("Could not create dialog box."));
        button = -1;
    } else {
        *(msg->reply) = NULL;
        /*GDK_THREADS_ENTER ();*/
        button = gnome_dialog_run_and_close (GNOME_DIALOG (dialog));
        /*GDK_THREADS_LEAVE ();*/
    }

    if (button == 1 || *(msg->reply) == NULL) {
        *(msg->success) = FALSE;
        *(msg->reply) = g_strdup (_("User cancelled query."));
    } else if (button > 0) {
        *(msg->success) = TRUE;
    }

    /* Allow the other thread to proceed */
    
    block_release (&modal_block);
    ui_set_busy ();
}

static void
get_password_cb (gchar * string, gpointer data)
{
    com_msg_t *msg = (com_msg_t *) data;

    if (string)
        *(msg->reply) = g_strdup (string);
    else
        *(msg->reply) = NULL;
}

static closure_t *
new_closure (const mail_operation_spec * spec, gpointer input,
         gboolean free_in_data)
{
    closure_t *clur;

    clur = g_new0 (closure_t, 1);
    clur->spec = spec;
    clur->in_data = input;
    clur->free_in_data = free_in_data;
    clur->ex = camel_exception_new ();

    clur->op_data = g_malloc (spec->datasize);

    camel_exception_init (clur->ex);

    clur->infinitive = (spec->describe) (input, FALSE);
    clur->gerund = (spec->describe) (input, TRUE);

    return clur;
}

static void
free_closure (closure_t *clur)
{
    clur->spec = NULL;

    if (clur->free_in_data)
        g_free (clur->in_data);
    clur->in_data = NULL;

    g_free (clur->op_data);
    clur->op_data = NULL;

    camel_exception_free (clur->ex);
    clur->ex = NULL;

    g_free (clur->infinitive);
    g_free (clur->gerund);

    g_free (clur);
}

/* ******************** */

/**
 *
 * Thread A calls block_prepare
 * Thread A causes thread B to do something
 * Thread A calls block_wait
 * Thread A continues when thread B calls block_release
 *
 * Thread B gets thread A's message
 * Thread B calls block_hold
 * Thread B does something
 * Thread B calls block_release
 *
 **/

static void
block_prepare (block_info_t *info)
{
    if (info->cond == NULL) {
        info->cond = g_cond_new ();
        info->mutex = g_mutex_new ();
    }

    g_mutex_lock (info->mutex);
    info->val = FALSE;
}

static void
block_wait (block_info_t *info)
{
    g_assert (info->cond);

    while (info->val == FALSE)
        g_cond_wait (info->cond, info->mutex);

    g_mutex_unlock (info->mutex);
}
static void
block_hold (block_info_t *info)
{
    g_assert (info->cond);

    g_mutex_lock (info->mutex);
    info->val = FALSE;
}

static void
block_release (block_info_t *info)
{
    g_assert (info->cond);

    info->val = TRUE;
    g_cond_signal (info->cond);
    g_mutex_unlock (info->mutex);
}

/* ******************** */

/* FIXME FIXME FIXME This is a totally evil hack.  */

static Evolution_ShellView
retrieve_shell_view_interface_from_control (BonoboControl *control)
{
    Bonobo_ControlFrame control_frame;
    Evolution_ShellView shell_view_interface;
    CORBA_Environment ev;

    control_frame = bonobo_control_get_control_frame (control);

    CORBA_exception_init (&ev);
    shell_view_interface = Bonobo_Unknown_query_interface (control_frame,
                                   "IDL:Evolution/ShellView:1.0",
                                   &ev);
    CORBA_exception_free (&ev);

    if (shell_view_interface != CORBA_OBJECT_NIL)
        gtk_object_set_data (GTK_OBJECT (control),
                     "mail_threads_shell_view_interface",
                     shell_view_interface);
    else
        g_warning ("Control frame doesn't have Evolution/ShellView.");

    return shell_view_interface;
}

static void
update_active_views (void)
{
    GList *active_controls;
    GList *p;

    active_controls = folder_browser_factory_get_active_control_list ();
    for (p = active_controls; p != NULL; p = p->next) {
        BonoboControl *control;
        Evolution_ShellView shell_view_interface;
        CORBA_Environment ev;

        control = BONOBO_CONTROL (p->data);

        shell_view_interface = gtk_object_get_data (GTK_OBJECT (control), "mail_threads_shell_view_interface");

        if (shell_view_interface == CORBA_OBJECT_NIL)
            shell_view_interface = retrieve_shell_view_interface_from_control (control);

        CORBA_exception_init (&ev);

        if (shell_view_interface != CORBA_OBJECT_NIL) {
            if (current_message == NULL && ! busy) {
                Evolution_ShellView_unset_message (shell_view_interface, &ev);
            } else {
                if (current_message == NULL)
                    Evolution_ShellView_set_message (shell_view_interface,
                                     "",
                                     busy,
                                     &ev);
                else
                    Evolution_ShellView_set_message (shell_view_interface,
                                     current_message,
                                     busy,
                                     &ev);
            }
        }

        CORBA_exception_free (&ev);
    }
}

static void 
ui_set_busy (void)
{
    busy = TRUE;
    update_active_views ();
}

static void 
ui_unset_busy (void)
{
    busy = FALSE;
    update_active_views ();
}

static void 
ui_set_message (const char *message)
{
    g_free (current_message);
    current_message = g_strdup (message);
    update_active_views ();
}

static void 
ui_unset_message (void)
{
    g_free (current_message);
    current_message = NULL;
    update_active_views ();
}