summaryrefslogtreecommitdiff
path: root/rts/eventlog/EventLog.c
blob: 60b960998ff56376fcac534f17b53bbd760cd5ca (plain)
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
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
/* -----------------------------------------------------------------------------
 *
 * (c) The GHC Team, 2008-2009
 *
 * Support for fast binary event logging.
 *
 * ---------------------------------------------------------------------------*/

#include "PosixSource.h"
#include "Rts.h"

#if defined(TRACING)

#include "Trace.h"
#include "Capability.h"
#include "RtsUtils.h"
#include "Stats.h"
#include "EventLog.h"

#include <string.h>
#include <stdio.h>
#if defined(HAVE_SYS_TYPES_H)
#include <sys/types.h>
#endif
#if defined(HAVE_UNISTD_H)
#include <unistd.h>
#endif

static const EventLogWriter *event_log_writer;

#define EVENT_LOG_SIZE 2 * (1024 * 1024) // 2MB

static int flushCount;

// Struct for record keeping of buffer to store event types and events.
typedef struct _EventsBuf {
  StgInt8 *begin;
  StgInt8 *pos;
  StgInt8 *marker;
  StgWord64 size;
  EventCapNo capno; // which capability this buffer belongs to, or -1
} EventsBuf;

EventsBuf *capEventBuf; // one EventsBuf for each Capability

EventsBuf eventBuf; // an EventsBuf not associated with any Capability
#if defined(THREADED_RTS)
Mutex eventBufMutex; // protected by this mutex
#endif

char *EventDesc[] = {
  [EVENT_CREATE_THREAD]       = "Create thread",
  [EVENT_RUN_THREAD]          = "Run thread",
  [EVENT_STOP_THREAD]         = "Stop thread",
  [EVENT_THREAD_RUNNABLE]     = "Thread runnable",
  [EVENT_MIGRATE_THREAD]      = "Migrate thread",
  [EVENT_THREAD_WAKEUP]       = "Wakeup thread",
  [EVENT_THREAD_LABEL]        = "Thread label",
  [EVENT_CAP_CREATE]          = "Create capability",
  [EVENT_CAP_DELETE]          = "Delete capability",
  [EVENT_CAP_DISABLE]         = "Disable capability",
  [EVENT_CAP_ENABLE]          = "Enable capability",
  [EVENT_GC_START]            = "Starting GC",
  [EVENT_GC_END]              = "Finished GC",
  [EVENT_REQUEST_SEQ_GC]      = "Request sequential GC",
  [EVENT_REQUEST_PAR_GC]      = "Request parallel GC",
  [EVENT_GC_GLOBAL_SYNC]      = "Synchronise stop-the-world GC",
  [EVENT_GC_STATS_GHC]        = "GC statistics",
  [EVENT_HEAP_INFO_GHC]       = "Heap static parameters",
  [EVENT_HEAP_ALLOCATED]      = "Total heap mem ever allocated",
  [EVENT_HEAP_SIZE]           = "Current heap size",
  [EVENT_HEAP_LIVE]           = "Current heap live data",
  [EVENT_CREATE_SPARK_THREAD] = "Create spark thread",
  [EVENT_LOG_MSG]             = "Log message",
  [EVENT_USER_MSG]            = "User message",
  [EVENT_USER_MARKER]         = "User marker",
  [EVENT_GC_IDLE]             = "GC idle",
  [EVENT_GC_WORK]             = "GC working",
  [EVENT_GC_DONE]             = "GC done",
  [EVENT_BLOCK_MARKER]        = "Block marker",
  [EVENT_CAPSET_CREATE]       = "Create capability set",
  [EVENT_CAPSET_DELETE]       = "Delete capability set",
  [EVENT_CAPSET_ASSIGN_CAP]   = "Add capability to capability set",
  [EVENT_CAPSET_REMOVE_CAP]   = "Remove capability from capability set",
  [EVENT_RTS_IDENTIFIER]      = "RTS name and version",
  [EVENT_PROGRAM_ARGS]        = "Program arguments",
  [EVENT_PROGRAM_ENV]         = "Program environment variables",
  [EVENT_OSPROCESS_PID]       = "Process ID",
  [EVENT_OSPROCESS_PPID]      = "Parent process ID",
  [EVENT_WALL_CLOCK_TIME]     = "Wall clock time",
  [EVENT_SPARK_COUNTERS]      = "Spark counters",
  [EVENT_SPARK_CREATE]        = "Spark create",
  [EVENT_SPARK_DUD]           = "Spark dud",
  [EVENT_SPARK_OVERFLOW]      = "Spark overflow",
  [EVENT_SPARK_RUN]           = "Spark run",
  [EVENT_SPARK_STEAL]         = "Spark steal",
  [EVENT_SPARK_FIZZLE]        = "Spark fizzle",
  [EVENT_SPARK_GC]            = "Spark GC",
  [EVENT_TASK_CREATE]         = "Task create",
  [EVENT_TASK_MIGRATE]        = "Task migrate",
  [EVENT_TASK_DELETE]         = "Task delete",
  [EVENT_HACK_BUG_T9003]      = "Empty event for bug #9003",
  [EVENT_HEAP_PROF_BEGIN]     = "Start of heap profile",
  [EVENT_HEAP_PROF_COST_CENTRE]   = "Cost center definition",
  [EVENT_HEAP_PROF_SAMPLE_BEGIN]  = "Start of heap profile sample",
  [EVENT_HEAP_BIO_PROF_SAMPLE_BEGIN]  = "Start of heap profile (biographical) sample",
  [EVENT_HEAP_PROF_SAMPLE_END]    = "End of heap profile sample",
  [EVENT_HEAP_PROF_SAMPLE_STRING] = "Heap profile string sample",
  [EVENT_HEAP_PROF_SAMPLE_COST_CENTRE] = "Heap profile cost-centre sample",
  [EVENT_USER_BINARY_MSG]     = "User binary message",
  [EVENT_CONC_MARK_BEGIN]        = "Begin concurrent mark phase",
  [EVENT_CONC_MARK_END]          = "End concurrent mark phase",
  [EVENT_CONC_SYNC_BEGIN]        = "Begin concurrent GC synchronisation",
  [EVENT_CONC_SYNC_END]          = "End concurrent GC synchronisation",
  [EVENT_CONC_SWEEP_BEGIN]       = "Begin concurrent sweep",
  [EVENT_CONC_SWEEP_END]         = "End concurrent sweep",
  [EVENT_CONC_UPD_REM_SET_FLUSH] = "Update remembered set flushed"
};

// Event type.

typedef struct _EventType {
  EventTypeNum etNum;  // Event Type number.
  uint32_t   size;     // size of the payload in bytes
  char *desc;     // Description
} EventType;

EventType eventTypes[NUM_GHC_EVENT_TAGS];

static void initEventsBuf(EventsBuf* eb, StgWord64 size, EventCapNo capno);
static void resetEventsBuf(EventsBuf* eb);
static void printAndClearEventBuf (EventsBuf *eventsBuf);

static void postEventType(EventsBuf *eb, EventType *et);

static void postLogMsg(EventsBuf *eb, EventTypeNum type, char *msg, va_list ap);

static void postBlockMarker(EventsBuf *eb);
static void closeBlockMarker(EventsBuf *ebuf);

static StgBool hasRoomForEvent(EventsBuf *eb, EventTypeNum eNum);
static StgBool hasRoomForVariableEvent(EventsBuf *eb, uint32_t payload_bytes);

static void ensureRoomForEvent(EventsBuf *eb, EventTypeNum tag);
static int ensureRoomForVariableEvent(EventsBuf *eb, StgWord16 size);

static inline void postWord8(EventsBuf *eb, StgWord8 i)
{
    *(eb->pos++) = i;
}

static inline void postWord16(EventsBuf *eb, StgWord16 i)
{
    postWord8(eb, (StgWord8)(i >> 8));
    postWord8(eb, (StgWord8)i);
}

static inline void postWord32(EventsBuf *eb, StgWord32 i)
{
    postWord16(eb, (StgWord16)(i >> 16));
    postWord16(eb, (StgWord16)i);
}

static inline void postWord64(EventsBuf *eb, StgWord64 i)
{
    postWord32(eb, (StgWord32)(i >> 32));
    postWord32(eb, (StgWord32)i);
}

static inline void postBuf(EventsBuf *eb, StgWord8 *buf, uint32_t size)
{
    memcpy(eb->pos, buf, size);
    eb->pos += size;
}

/* Post a null-terminated string to the event log.
 * It is the caller's responsibility to ensure that there is
 * enough room for strlen(buf)+1 bytes.
 */
static inline void postString(EventsBuf *eb, const char *buf)
{
    if (buf) {
        const int len = strlen(buf);
        ASSERT(eb->begin + eb->size > eb->pos + len);
        memcpy(eb->pos, buf, len);
        eb->pos += len;
    }
    *eb->pos = 0;
    eb->pos++;
}

static inline StgWord64 time_ns(void)
{ return TimeToNS(stat_getElapsedTime()); }

static inline void postEventTypeNum(EventsBuf *eb, EventTypeNum etNum)
{ postWord16(eb, etNum); }

static inline void postTimestamp(EventsBuf *eb)
{ postWord64(eb, time_ns()); }

static inline void postThreadID(EventsBuf *eb, EventThreadID id)
{ postWord32(eb,id); }

static inline void postCapNo(EventsBuf *eb, EventCapNo no)
{ postWord16(eb,no); }

static inline void postCapsetID(EventsBuf *eb, EventCapsetID id)
{ postWord32(eb,id); }

static inline void postCapsetType(EventsBuf *eb, EventCapsetType type)
{ postWord16(eb,type); }

static inline void postOSProcessId(EventsBuf *eb, pid_t pid)
{ postWord32(eb, pid); }

static inline void postKernelThreadId(EventsBuf *eb, EventKernelThreadId tid)
{ postWord64(eb, tid); }

static inline void postTaskId(EventsBuf *eb, EventTaskId tUniq)
{ postWord64(eb, tUniq); }

static inline void postPayloadSize(EventsBuf *eb, EventPayloadSize size)
{ postWord16(eb,size); }

static inline void postEventHeader(EventsBuf *eb, EventTypeNum type)
{
    postEventTypeNum(eb, type);
    postTimestamp(eb);
}

static inline void postInt8(EventsBuf *eb, StgInt8 i)
{ postWord8(eb, (StgWord8)i); }

static inline void postInt32(EventsBuf *eb, StgInt32 i)
{ postWord32(eb, (StgWord32)i); }

#define EVENT_SIZE_DYNAMIC (-1)

static void
initEventLogWriter(void)
{
    if (event_log_writer != NULL &&
            event_log_writer->initEventLogWriter != NULL) {
        event_log_writer->initEventLogWriter();
    }
}

static bool
writeEventLog(void *eventlog, size_t eventlog_size)
{
    if (event_log_writer != NULL &&
            event_log_writer->writeEventLog != NULL) {
        return event_log_writer->writeEventLog(eventlog, eventlog_size);
    } else {
        return false;
    }
}

static void
stopEventLogWriter(void)
{
    if (event_log_writer != NULL &&
            event_log_writer->stopEventLogWriter != NULL) {
        event_log_writer->stopEventLogWriter();
    }
}

void
flushEventLog(void)
{
    if (event_log_writer != NULL &&
            event_log_writer->flushEventLog != NULL) {
        event_log_writer->flushEventLog();
    }
}

static void
init_event_types(void)
{
    for (int t = 0; t < NUM_GHC_EVENT_TAGS; ++t) {
        eventTypes[t].etNum = t;
        eventTypes[t].desc = EventDesc[t];

        switch (t) {
        case EVENT_CREATE_THREAD:   // (cap, thread)
        case EVENT_RUN_THREAD:      // (cap, thread)
        case EVENT_THREAD_RUNNABLE: // (cap, thread)
        case EVENT_CREATE_SPARK_THREAD: // (cap, spark_thread)
            eventTypes[t].size = sizeof(EventThreadID);
            break;

        case EVENT_MIGRATE_THREAD:  // (cap, thread, new_cap)
        case EVENT_THREAD_WAKEUP:   // (cap, thread, other_cap)
            eventTypes[t].size =
                sizeof(EventThreadID) + sizeof(EventCapNo);
            break;

        case EVENT_STOP_THREAD:     // (cap, thread, status)
            eventTypes[t].size = sizeof(EventThreadID)
                               + sizeof(StgWord16)
                               + sizeof(EventThreadID);
            break;

        case EVENT_CAP_CREATE:      // (cap)
        case EVENT_CAP_DELETE:      // (cap)
        case EVENT_CAP_ENABLE:      // (cap)
        case EVENT_CAP_DISABLE:     // (cap)
            eventTypes[t].size = sizeof(EventCapNo);
            break;

        case EVENT_CAPSET_CREATE:   // (capset, capset_type)
            eventTypes[t].size =
                sizeof(EventCapsetID) + sizeof(EventCapsetType);
            break;

        case EVENT_CAPSET_DELETE:   // (capset)
            eventTypes[t].size = sizeof(EventCapsetID);
            break;

        case EVENT_CAPSET_ASSIGN_CAP:  // (capset, cap)
        case EVENT_CAPSET_REMOVE_CAP:
            eventTypes[t].size =
                sizeof(EventCapsetID) + sizeof(EventCapNo);
            break;

        case EVENT_OSPROCESS_PID:   // (cap, pid)
        case EVENT_OSPROCESS_PPID:
            eventTypes[t].size =
                sizeof(EventCapsetID) + sizeof(StgWord32);
            break;

        case EVENT_WALL_CLOCK_TIME: // (capset, unix_epoch_seconds, nanoseconds)
            eventTypes[t].size =
                sizeof(EventCapsetID) + sizeof(StgWord64) + sizeof(StgWord32);
            break;

        case EVENT_SPARK_STEAL:     // (cap, victim_cap)
            eventTypes[t].size =
                sizeof(EventCapNo);
            break;

        case EVENT_REQUEST_SEQ_GC:  // (cap)
        case EVENT_REQUEST_PAR_GC:  // (cap)
        case EVENT_GC_START:        // (cap)
        case EVENT_GC_END:          // (cap)
        case EVENT_GC_IDLE:
        case EVENT_GC_WORK:
        case EVENT_GC_DONE:
        case EVENT_GC_GLOBAL_SYNC:  // (cap)
        case EVENT_SPARK_CREATE:    // (cap)
        case EVENT_SPARK_DUD:       // (cap)
        case EVENT_SPARK_OVERFLOW:  // (cap)
        case EVENT_SPARK_RUN:       // (cap)
        case EVENT_SPARK_FIZZLE:    // (cap)
        case EVENT_SPARK_GC:        // (cap)
            eventTypes[t].size = 0;
            break;

        case EVENT_LOG_MSG:          // (msg)
        case EVENT_USER_MSG:         // (msg)
        case EVENT_USER_MARKER:      // (markername)
        case EVENT_RTS_IDENTIFIER:   // (capset, str)
        case EVENT_PROGRAM_ARGS:     // (capset, strvec)
        case EVENT_PROGRAM_ENV:      // (capset, strvec)
        case EVENT_THREAD_LABEL:     // (thread, str)
            eventTypes[t].size = 0xffff;
            break;

        case EVENT_SPARK_COUNTERS:   // (cap, 7*counter)
            eventTypes[t].size = 7 * sizeof(StgWord64);
            break;

        case EVENT_HEAP_ALLOCATED:    // (heap_capset, alloc_bytes)
        case EVENT_HEAP_SIZE:         // (heap_capset, size_bytes)
        case EVENT_HEAP_LIVE:         // (heap_capset, live_bytes)
            eventTypes[t].size = sizeof(EventCapsetID) + sizeof(StgWord64);
            break;

        case EVENT_HEAP_INFO_GHC:     // (heap_capset, n_generations,
                                      //  max_heap_size, alloc_area_size,
                                      //  mblock_size, block_size)
            eventTypes[t].size = sizeof(EventCapsetID)
                               + sizeof(StgWord16)
                               + sizeof(StgWord64) * 4;
            break;

        case EVENT_GC_STATS_GHC:      // (heap_capset, generation,
                                      //  copied_bytes, slop_bytes, frag_bytes,
                                      //  par_n_threads,
                                      //  par_max_copied, par_tot_copied,
                                      //  par_balanced_copied
                                      //  )
            eventTypes[t].size = sizeof(EventCapsetID)
                               + sizeof(StgWord16)
                               + sizeof(StgWord64) * 3
                               + sizeof(StgWord32)
                               + sizeof(StgWord64) * 3;
            break;

        case EVENT_TASK_CREATE:   // (taskId, cap, tid)
            eventTypes[t].size = sizeof(EventTaskId)
                               + sizeof(EventCapNo)
                               + sizeof(EventKernelThreadId);
            break;

        case EVENT_TASK_MIGRATE:   // (taskId, cap, new_cap)
            eventTypes[t].size =
                sizeof(EventTaskId) + sizeof(EventCapNo) + sizeof(EventCapNo);
            break;

        case EVENT_TASK_DELETE:   // (taskId)
            eventTypes[t].size = sizeof(EventTaskId);
            break;

        case EVENT_BLOCK_MARKER:
            eventTypes[t].size = sizeof(StgWord32) + sizeof(EventTimestamp) +
                sizeof(EventCapNo);
            break;

        case EVENT_HACK_BUG_T9003:
            eventTypes[t].size = 0;
            break;

        case EVENT_HEAP_PROF_BEGIN:
            eventTypes[t].size = EVENT_SIZE_DYNAMIC;
            break;

        case EVENT_HEAP_PROF_COST_CENTRE:
            eventTypes[t].size = EVENT_SIZE_DYNAMIC;
            break;

        case EVENT_HEAP_PROF_SAMPLE_BEGIN:
            eventTypes[t].size = 8;
            break;

        case EVENT_HEAP_BIO_PROF_SAMPLE_BEGIN:
            eventTypes[t].size = 16;
            break;

        case EVENT_HEAP_PROF_SAMPLE_END:
            eventTypes[t].size = 8;
            break;

        case EVENT_HEAP_PROF_SAMPLE_STRING:
            eventTypes[t].size = EVENT_SIZE_DYNAMIC;
            break;

        case EVENT_HEAP_PROF_SAMPLE_COST_CENTRE:
            eventTypes[t].size = EVENT_SIZE_DYNAMIC;
            break;

        case EVENT_USER_BINARY_MSG:
            eventTypes[t].size = EVENT_SIZE_DYNAMIC;
            break;

        case EVENT_CONC_MARK_BEGIN:
        case EVENT_CONC_SYNC_BEGIN:
        case EVENT_CONC_SYNC_END:
        case EVENT_CONC_SWEEP_BEGIN:
        case EVENT_CONC_SWEEP_END:
            eventTypes[t].size = 0;
            break;

        case EVENT_CONC_MARK_END:
            eventTypes[t].size = 4;
            break;

        case EVENT_CONC_UPD_REM_SET_FLUSH: // (cap)
            eventTypes[t].size =
                sizeof(EventCapNo);
            break;

        default:
            continue; /* ignore deprecated events */
        }
    }
}

static void
postHeaderEvents(void)
{
    // Write in buffer: the header begin marker.
    postInt32(&eventBuf, EVENT_HEADER_BEGIN);

    // Mark beginning of event types in the header.
    postInt32(&eventBuf, EVENT_HET_BEGIN);

    for (int t = 0; t < NUM_GHC_EVENT_TAGS; ++t) {
        // Write in buffer: the start event type.
        if (eventTypes[t].desc)
            postEventType(&eventBuf, &eventTypes[t]);
    }

    // Mark end of event types in the header.
    postInt32(&eventBuf, EVENT_HET_END);

    // Write in buffer: the header end marker.
    postInt32(&eventBuf, EVENT_HEADER_END);

    // Prepare event buffer for events (data).
    postInt32(&eventBuf, EVENT_DATA_BEGIN);
}

void
initEventLogging(const EventLogWriter *ev_writer)
{
    uint32_t n_caps;

    init_event_types();

    event_log_writer = ev_writer;
    initEventLogWriter();

    if (sizeof(EventDesc) / sizeof(char*) != NUM_GHC_EVENT_TAGS) {
        barf("EventDesc array has the wrong number of elements");
    }

    /*
     * Allocate buffer(s) to store events.
     * Create buffer large enough for the header begin marker, all event
     * types, and header end marker to prevent checking if buffer has room
     * for each of these steps, and remove the need to flush the buffer to
     * disk during initialization.
     *
     * Use a single buffer to store the header with event types, then flush
     * the buffer so all buffers are empty for writing events.
     */
#if defined(THREADED_RTS)
    // XXX n_capabilities hasn't been initialized yet
    n_caps = RtsFlags.ParFlags.nCapabilities;
#else
    n_caps = 1;
#endif
    moreCapEventBufs(0, n_caps);

    initEventsBuf(&eventBuf, EVENT_LOG_SIZE, (EventCapNo)(-1));
#if defined(THREADED_RTS)
    initMutex(&eventBufMutex);
#endif

    postHeaderEvents();

    // Flush capEventBuf with header.
    /*
     * Flush header and data begin marker to the file, thus preparing the
     * file to have events written to it.
     */
    printAndClearEventBuf(&eventBuf);

    for (uint32_t c = 0; c < n_caps; ++c) {
        postBlockMarker(&capEventBuf[c]);
    }
}

void
endEventLogging(void)
{
    // Flush all events remaining in the buffers.
    for (uint32_t c = 0; c < n_capabilities; ++c) {
        printAndClearEventBuf(&capEventBuf[c]);
    }
    printAndClearEventBuf(&eventBuf);
    resetEventsBuf(&eventBuf); // we don't want the block marker

    // Mark end of events (data).
    postEventTypeNum(&eventBuf, EVENT_DATA_END);

    // Flush the end of data marker.
    printAndClearEventBuf(&eventBuf);

    stopEventLogWriter();
}

void
moreCapEventBufs (uint32_t from, uint32_t to)
{
    if (from > 0) {
        capEventBuf = stgReallocBytes(capEventBuf, to * sizeof(EventsBuf),
                                      "moreCapEventBufs");
    } else {
        capEventBuf = stgMallocBytes(to * sizeof(EventsBuf),
                                     "moreCapEventBufs");
    }

    for (uint32_t c = from; c < to; ++c) {
        initEventsBuf(&capEventBuf[c], EVENT_LOG_SIZE, c);
    }

    // The from == 0 already covered in initEventLogging, so we are interested
    // only in case when we are increasing capabilities number
    if (from > 0) {
        for (uint32_t c = from; c < to; ++c) {
           postBlockMarker(&capEventBuf[c]);
        }
    }
}


void
freeEventLogging(void)
{
    // Free events buffer.
    for (uint32_t c = 0; c < n_capabilities; ++c) {
        if (capEventBuf[c].begin != NULL)
            stgFree(capEventBuf[c].begin);
    }
    if (capEventBuf != NULL)  {
        stgFree(capEventBuf);
    }
}

void
abortEventLogging(void)
{
    freeEventLogging();
    stopEventLogWriter();
}

/*
 * Post an event message to the capability's eventlog buffer.
 * If the buffer is full, prints out the buffer and clears it.
 */
void
postSchedEvent (Capability *cap,
                EventTypeNum tag,
                StgThreadID thread,
                StgWord info1,
                StgWord info2)
{
    EventsBuf *eb = &capEventBuf[cap->no];
    ensureRoomForEvent(eb, tag);

    postEventHeader(eb, tag);

    switch (tag) {
    case EVENT_CREATE_THREAD:   // (cap, thread)
    case EVENT_RUN_THREAD:      // (cap, thread)
    case EVENT_THREAD_RUNNABLE: // (cap, thread)
    {
        postThreadID(eb,thread);
        break;
    }

    case EVENT_CREATE_SPARK_THREAD: // (cap, spark_thread)
    {
        postThreadID(eb,info1 /* spark_thread */);
        break;
    }

    case EVENT_MIGRATE_THREAD:  // (cap, thread, new_cap)
    case EVENT_THREAD_WAKEUP:   // (cap, thread, other_cap)
    {
        postThreadID(eb,thread);
        postCapNo(eb,info1 /* new_cap | victim_cap | other_cap */);
        break;
   }

    case EVENT_STOP_THREAD:     // (cap, thread, status)
    {
        postThreadID(eb,thread);
        postWord16(eb,info1 /* status */);
        postThreadID(eb,info2 /* blocked on thread */);
        break;
    }

    default:
        barf("postSchedEvent: unknown event tag %d", tag);
    }
}

void
postSparkEvent (Capability *cap,
                EventTypeNum tag,
                StgWord info1)
{
    EventsBuf *eb = &capEventBuf[cap->no];
    ensureRoomForEvent(eb, tag);

    postEventHeader(eb, tag);

    switch (tag) {
    case EVENT_CREATE_SPARK_THREAD: // (cap, spark_thread)
    {
        postThreadID(eb,info1 /* spark_thread */);
        break;
    }

    case EVENT_SPARK_STEAL:         // (cap, victim_cap)
    {
        postCapNo(eb,info1 /* victim_cap */);
        break;
   }

    case EVENT_SPARK_CREATE:        // (cap)
    case EVENT_SPARK_DUD:           // (cap)
    case EVENT_SPARK_OVERFLOW:      // (cap)
    case EVENT_SPARK_RUN:           // (cap)
    case EVENT_SPARK_FIZZLE:        // (cap)
    case EVENT_SPARK_GC:            // (cap)
    {
        break;
    }

    default:
        barf("postSparkEvent: unknown event tag %d", tag);
    }
}

void
postSparkCountersEvent (Capability *cap,
                        SparkCounters counters,
                        StgWord remaining)
{
    EventsBuf *eb = &capEventBuf[cap->no];
    ensureRoomForEvent(eb, EVENT_SPARK_COUNTERS);

    postEventHeader(eb, EVENT_SPARK_COUNTERS);
    /* EVENT_SPARK_COUNTERS (crt,dud,ovf,cnv,gcd,fiz,rem) */
    postWord64(eb,counters.created);
    postWord64(eb,counters.dud);
    postWord64(eb,counters.overflowed);
    postWord64(eb,counters.converted);
    postWord64(eb,counters.gcd);
    postWord64(eb,counters.fizzled);
    postWord64(eb,remaining);
}

void
postCapEvent (EventTypeNum  tag,
              EventCapNo    capno)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, tag);

    postEventHeader(&eventBuf, tag);

    switch (tag) {
    case EVENT_CAP_CREATE:   // (cap)
    case EVENT_CAP_DELETE:   // (cap)
    case EVENT_CAP_ENABLE:   // (cap)
    case EVENT_CAP_DISABLE:  // (cap)
    {
        postCapNo(&eventBuf,capno);
        break;
    }

    default:
        barf("postCapEvent: unknown event tag %d", tag);
    }

    RELEASE_LOCK(&eventBufMutex);
}

void postCapsetEvent (EventTypeNum tag,
                      EventCapsetID capset,
                      StgWord info)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, tag);

    postEventHeader(&eventBuf, tag);
    postCapsetID(&eventBuf, capset);

    switch (tag) {
    case EVENT_CAPSET_CREATE:   // (capset, capset_type)
    {
        postCapsetType(&eventBuf, info /* capset_type */);
        break;
    }

    case EVENT_CAPSET_DELETE:   // (capset)
    {
        break;
    }

    case EVENT_CAPSET_ASSIGN_CAP:  // (capset, capno)
    case EVENT_CAPSET_REMOVE_CAP:  // (capset, capno)
    {
        postCapNo(&eventBuf, info /* capno */);
        break;
    }
    case EVENT_OSPROCESS_PID:   // (capset, pid)
    case EVENT_OSPROCESS_PPID:  // (capset, parent_pid)
    {
        postOSProcessId(&eventBuf, info);
        break;
    }
    default:
        barf("postCapsetEvent: unknown event tag %d", tag);
    }

    RELEASE_LOCK(&eventBufMutex);
}

void postCapsetStrEvent (EventTypeNum tag,
                         EventCapsetID capset,
                         char *msg)
{
    int strsize = strlen(msg);
    int size = strsize + sizeof(EventCapsetID);
    if (size > EVENT_PAYLOAD_SIZE_MAX) {
        errorBelch("Event size exceeds EVENT_PAYLOAD_SIZE_MAX, bail out");
        return;
    }

    ACQUIRE_LOCK(&eventBufMutex);

    if (!hasRoomForVariableEvent(&eventBuf, size)){
        printAndClearEventBuf(&eventBuf);

        if (!hasRoomForVariableEvent(&eventBuf, size)){
            errorBelch("Event size exceeds buffer size, bail out");
            RELEASE_LOCK(&eventBufMutex);
            return;
        }
    }

    postEventHeader(&eventBuf, tag);
    postPayloadSize(&eventBuf, size);
    postCapsetID(&eventBuf, capset);

    postBuf(&eventBuf, (StgWord8*) msg, strsize);

    RELEASE_LOCK(&eventBufMutex);
}

void postCapsetVecEvent (EventTypeNum tag,
                         EventCapsetID capset,
                         int argc,
                         char *argv[])
{
    int size = sizeof(EventCapsetID);

    for (int i = 0; i < argc; i++) {
        // 1 + strlen to account for the trailing \0, used as separator
        size += 1 + strlen(argv[i]);
    }

    ACQUIRE_LOCK(&eventBufMutex);

    if (!hasRoomForVariableEvent(&eventBuf, size)){
        printAndClearEventBuf(&eventBuf);

        if(!hasRoomForVariableEvent(&eventBuf, size)){
            errorBelch("Event size exceeds buffer size, bail out");
            RELEASE_LOCK(&eventBufMutex);
            return;
        }
    }

    postEventHeader(&eventBuf, tag);
    postPayloadSize(&eventBuf, size);
    postCapsetID(&eventBuf, capset);

    for (int i = 0; i < argc; i++) {
        // again, 1 + to account for \0
        postBuf(&eventBuf, (StgWord8*) argv[i], 1 + strlen(argv[i]));
    }

    RELEASE_LOCK(&eventBufMutex);
}

void postWallClockTime (EventCapsetID capset)
{
    StgWord64 ts;
    StgWord64 sec;
    StgWord32 nsec;

    ACQUIRE_LOCK(&eventBufMutex);

    /* The EVENT_WALL_CLOCK_TIME event is intended to allow programs
       reading the eventlog to match up the event timestamps with wall
       clock time. The normal event timestamps measure time since the
       start of the program. To align eventlogs from concurrent
       processes we need to be able to match up the timestamps. One way
       to do this is if we know how the timestamps and wall clock time
       match up (and of course if both processes have sufficiently
       synchronised clocks).

       So we want to make sure that the timestamp that we generate for
       this event matches up very closely with the wall clock time.
       Unfortunately we currently have to use two different APIs to get
       the elapsed time vs the wall clock time. So to minimise the
       difference we just call them very close together.
     */

    getUnixEpochTime(&sec, &nsec);  /* Get the wall clock time */
    ts = time_ns();                 /* Get the eventlog timestamp */
    ensureRoomForEvent(&eventBuf, EVENT_WALL_CLOCK_TIME);

    /* Normally we'd call postEventHeader(), but that generates its own
       timestamp, so we go one level lower so we can write out the
       timestamp we already generated above. */
    postEventTypeNum(&eventBuf, EVENT_WALL_CLOCK_TIME);
    postWord64(&eventBuf, ts);

    /* EVENT_WALL_CLOCK_TIME (capset, unix_epoch_seconds, nanoseconds) */
    postCapsetID(&eventBuf, capset);
    postWord64(&eventBuf, sec);
    postWord32(&eventBuf, nsec);

    RELEASE_LOCK(&eventBufMutex);
}

/*
 * Various GC and heap events
 */
void postHeapEvent (Capability    *cap,
                    EventTypeNum   tag,
                    EventCapsetID  heap_capset,
                    W_           info1)
{
    EventsBuf *eb = &capEventBuf[cap->no];
    ensureRoomForEvent(eb, tag);

    postEventHeader(eb, tag);

    switch (tag) {
    case EVENT_HEAP_ALLOCATED:     // (heap_capset, alloc_bytes)
    case EVENT_HEAP_SIZE:          // (heap_capset, size_bytes)
    case EVENT_HEAP_LIVE:          // (heap_capset, live_bytes)
    {
        postCapsetID(eb, heap_capset);
        postWord64(eb, info1 /* alloc/size/live_bytes */);
        break;
    }

    default:
        barf("postHeapEvent: unknown event tag %d", tag);
    }
}

void postEventHeapInfo (EventCapsetID heap_capset,
                        uint32_t    gens,
                        W_          maxHeapSize,
                        W_          allocAreaSize,
                        W_          mblockSize,
                        W_          blockSize)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, EVENT_HEAP_INFO_GHC);

    postEventHeader(&eventBuf, EVENT_HEAP_INFO_GHC);
    /* EVENT_HEAP_INFO_GHC (heap_capset, n_generations,
                            max_heap_size, alloc_area_size,
                            mblock_size, block_size) */
    postCapsetID(&eventBuf, heap_capset);
    postWord16(&eventBuf, gens);
    postWord64(&eventBuf, maxHeapSize);
    postWord64(&eventBuf, allocAreaSize);
    postWord64(&eventBuf, mblockSize);
    postWord64(&eventBuf, blockSize);

    RELEASE_LOCK(&eventBufMutex);
}

void postEventGcStats  (Capability    *cap,
                        EventCapsetID  heap_capset,
                        uint32_t     gen,
                        W_           copied,
                        W_           slop,
                        W_           fragmentation,
                        uint32_t     par_n_threads,
                        W_           par_max_copied,
                        W_           par_tot_copied,
                        W_           par_balanced_copied)
{
    EventsBuf *eb = &capEventBuf[cap->no];
    ensureRoomForEvent(eb, EVENT_GC_STATS_GHC);

    postEventHeader(eb, EVENT_GC_STATS_GHC);
    /* EVENT_GC_STATS_GHC (heap_capset, generation,
                           copied_bytes, slop_bytes, frag_bytes,
                           par_n_threads, par_max_copied,
                           par_tot_copied, par_balanced_copied) */
    postCapsetID(eb, heap_capset);
    postWord16(eb, gen);
    postWord64(eb, copied);
    postWord64(eb, slop);
    postWord64(eb, fragmentation);
    postWord32(eb, par_n_threads);
    postWord64(eb, par_max_copied);
    postWord64(eb, par_tot_copied);
    postWord64(eb, par_balanced_copied);
}

void postTaskCreateEvent (EventTaskId taskId,
                          EventCapNo capno,
                          EventKernelThreadId tid)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, EVENT_TASK_CREATE);

    postEventHeader(&eventBuf, EVENT_TASK_CREATE);
    /* EVENT_TASK_CREATE (taskID, cap, tid) */
    postTaskId(&eventBuf, taskId);
    postCapNo(&eventBuf, capno);
    postKernelThreadId(&eventBuf, tid);

    RELEASE_LOCK(&eventBufMutex);
}

void postTaskMigrateEvent (EventTaskId taskId,
                           EventCapNo capno,
                           EventCapNo new_capno)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, EVENT_TASK_MIGRATE);

    postEventHeader(&eventBuf, EVENT_TASK_MIGRATE);
    /* EVENT_TASK_MIGRATE (taskID, cap, new_cap) */
    postTaskId(&eventBuf, taskId);
    postCapNo(&eventBuf, capno);
    postCapNo(&eventBuf, new_capno);

    RELEASE_LOCK(&eventBufMutex);
}

void postTaskDeleteEvent (EventTaskId taskId)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, EVENT_TASK_DELETE);

    postEventHeader(&eventBuf, EVENT_TASK_DELETE);
    /* EVENT_TASK_DELETE (taskID) */
    postTaskId(&eventBuf, taskId);

    RELEASE_LOCK(&eventBufMutex);
}

void
postEventNoCap (EventTypeNum tag)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, tag);
    postEventHeader(&eventBuf, tag);
    RELEASE_LOCK(&eventBufMutex);
}

void
postEvent (Capability *cap, EventTypeNum tag)
{
    EventsBuf *eb = &capEventBuf[cap->no];
    ensureRoomForEvent(eb, tag);
    postEventHeader(eb, tag);
}

void
postEventAtTimestamp (Capability *cap, EventTimestamp ts, EventTypeNum tag)
{
    EventsBuf *eb = &capEventBuf[cap->no];
    ensureRoomForEvent(eb, tag);

    /* Normally we'd call postEventHeader(), but that generates its own
       timestamp, so we go one level lower so we can write out
       the timestamp we received as an argument. */
    postEventTypeNum(eb, tag);
    postWord64(eb, ts);
}

#define BUF 512

void postLogMsg(EventsBuf *eb, EventTypeNum type, char *msg, va_list ap)
{
    char buf[BUF];
    uint32_t size = vsnprintf(buf, BUF, msg,ap);
    if (size > BUF) {
        buf[BUF-1] = '\0';
        size = BUF;
    }

    ensureRoomForVariableEvent(eb, size);

    postEventHeader(eb, type);
    postPayloadSize(eb, size);
    postBuf(eb,(StgWord8*)buf,size);
}

void postMsg(char *msg, va_list ap)
{
    ACQUIRE_LOCK(&eventBufMutex);
    postLogMsg(&eventBuf, EVENT_LOG_MSG, msg, ap);
    RELEASE_LOCK(&eventBufMutex);
}

void postCapMsg(Capability *cap, char *msg, va_list ap)
{
    postLogMsg(&capEventBuf[cap->no], EVENT_LOG_MSG, msg, ap);
}

void postUserEvent(Capability *cap, EventTypeNum type, char *msg)
{
    const size_t size = strlen(msg);
    if (size > EVENT_PAYLOAD_SIZE_MAX) {
        errorBelch("Event size exceeds EVENT_PAYLOAD_SIZE_MAX, bail out");
        return;
    }

    EventsBuf *eb = &capEventBuf[cap->no];
    if (!hasRoomForVariableEvent(eb, size)){
        printAndClearEventBuf(eb);

        if (!hasRoomForVariableEvent(eb, size)){
            errorBelch("Event size exceeds buffer size, bail out");
            return;
        }
    }

    postEventHeader(eb, type);
    postPayloadSize(eb, size);
    postBuf(eb, (StgWord8*) msg, size);
}

void postUserBinaryEvent(Capability   *cap,
                         EventTypeNum  type,
                         uint8_t      *msg,
                         size_t        size)
{
    if (size > EVENT_PAYLOAD_SIZE_MAX) {
        errorBelch("Event size exceeds EVENT_PAYLOAD_SIZE_MAX, bail out");
        return;
    }

    EventsBuf *eb = &capEventBuf[cap->no];
    if (!hasRoomForVariableEvent(eb, size)){
        printAndClearEventBuf(eb);

        if (!hasRoomForVariableEvent(eb, size)){
            errorBelch("Event size exceeds buffer size, bail out");
            return;
        }
    }

    postEventHeader(eb, type);
    postPayloadSize(eb, size);
    postBuf(eb, (StgWord8*) msg, size);
}

void postThreadLabel(Capability    *cap,
                     EventThreadID  id,
                     char          *label)
{
    const int strsize = strlen(label);
    const int size = strsize + sizeof(EventThreadID);
    if (size > EVENT_PAYLOAD_SIZE_MAX) {
        errorBelch("Event size exceeds EVENT_PAYLOAD_SIZE_MAX, bail out");
        return;
    }

    EventsBuf *eb = &capEventBuf[cap->no];
    if (!hasRoomForVariableEvent(eb, size)){
        printAndClearEventBuf(eb);

        if (!hasRoomForVariableEvent(eb, size)){
            errorBelch("Event size exceeds buffer size, bail out");
            return;
        }
    }

    postEventHeader(eb, EVENT_THREAD_LABEL);
    postPayloadSize(eb, size);
    postThreadID(eb, id);
    postBuf(eb, (StgWord8*) label, strsize);
}

void postConcUpdRemSetFlush(Capability *cap)
{
    EventsBuf *eb = &capEventBuf[cap->no];
    ensureRoomForEvent(eb, EVENT_CONC_UPD_REM_SET_FLUSH);
    postEventHeader(eb, EVENT_CONC_UPD_REM_SET_FLUSH);
    postCapNo(eb, cap->no);
}

void postConcMarkEnd(StgWord32 marked_obj_count)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, EVENT_CONC_MARK_END);
    postEventHeader(&eventBuf, EVENT_CONC_MARK_END);
    postWord32(&eventBuf, marked_obj_count);
    RELEASE_LOCK(&eventBufMutex);
}

void closeBlockMarker (EventsBuf *ebuf)
{
    if (ebuf->marker)
    {
        // (type:16, time:64, size:32, end_time:64)

        StgInt8* save_pos = ebuf->pos;
        ebuf->pos = ebuf->marker + sizeof(EventTypeNum) +
                    sizeof(EventTimestamp);
        postWord32(ebuf, save_pos - ebuf->marker);
        postTimestamp(ebuf);
        ebuf->pos = save_pos;
        ebuf->marker = NULL;
    }
}


void postBlockMarker (EventsBuf *eb)
{
    ensureRoomForEvent(eb, EVENT_BLOCK_MARKER);

    closeBlockMarker(eb);

    eb->marker = eb->pos;
    postEventHeader(eb, EVENT_BLOCK_MARKER);
    postWord32(eb,0); // these get filled in later by closeBlockMarker();
    postWord64(eb,0);
    postCapNo(eb, eb->capno);
}

static HeapProfBreakdown getHeapProfBreakdown(void)
{
    switch (RtsFlags.ProfFlags.doHeapProfile) {
    case HEAP_BY_CCS:
        return HEAP_PROF_BREAKDOWN_COST_CENTRE;
    case HEAP_BY_MOD:
        return HEAP_PROF_BREAKDOWN_MODULE;
    case HEAP_BY_DESCR:
        return HEAP_PROF_BREAKDOWN_CLOSURE_DESCR;
    case HEAP_BY_TYPE:
        return HEAP_PROF_BREAKDOWN_TYPE_DESCR;
    case HEAP_BY_RETAINER:
        return HEAP_PROF_BREAKDOWN_RETAINER;
    case HEAP_BY_LDV:
        return HEAP_PROF_BREAKDOWN_BIOGRAPHY;
    case HEAP_BY_CLOSURE_TYPE:
        return HEAP_PROF_BREAKDOWN_CLOSURE_TYPE;
    default:
        barf("getHeapProfBreakdown: unknown heap profiling mode");
    }
}

void postHeapProfBegin(StgWord8 profile_id)
{
    ACQUIRE_LOCK(&eventBufMutex);
    PROFILING_FLAGS *flags = &RtsFlags.ProfFlags;
    StgWord modSelector_len   =
        flags->modSelector ? strlen(flags->modSelector) : 0;
    StgWord descrSelector_len =
        flags->descrSelector ? strlen(flags->descrSelector) : 0;
    StgWord typeSelector_len  =
        flags->typeSelector ? strlen(flags->typeSelector) : 0;
    StgWord ccSelector_len    =
        flags->ccSelector ? strlen(flags->ccSelector) : 0;
    StgWord ccsSelector_len   =
        flags->ccsSelector ? strlen(flags->ccsSelector) : 0;
    StgWord retainerSelector_len =
        flags->retainerSelector ? strlen(flags->retainerSelector) : 0;
    StgWord bioSelector_len   =
        flags->bioSelector ? strlen(flags->bioSelector) : 0;
    StgWord len =
        1+8+4 + modSelector_len + descrSelector_len +
        typeSelector_len + ccSelector_len + ccsSelector_len +
        retainerSelector_len + bioSelector_len + 7;
    ensureRoomForVariableEvent(&eventBuf, len);
    postEventHeader(&eventBuf, EVENT_HEAP_PROF_BEGIN);
    postPayloadSize(&eventBuf, len);
    postWord8(&eventBuf, profile_id);
    postWord64(&eventBuf, TimeToNS(flags->heapProfileInterval));
    postWord32(&eventBuf, getHeapProfBreakdown());
    postString(&eventBuf, flags->modSelector);
    postString(&eventBuf, flags->descrSelector);
    postString(&eventBuf, flags->typeSelector);
    postString(&eventBuf, flags->ccSelector);
    postString(&eventBuf, flags->ccsSelector);
    postString(&eventBuf, flags->retainerSelector);
    postString(&eventBuf, flags->bioSelector);
    RELEASE_LOCK(&eventBufMutex);
}

void postHeapProfSampleBegin(StgInt era)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, EVENT_HEAP_PROF_SAMPLE_BEGIN);
    postEventHeader(&eventBuf, EVENT_HEAP_PROF_SAMPLE_BEGIN);
    postWord64(&eventBuf, era);
    RELEASE_LOCK(&eventBufMutex);
}


void postHeapBioProfSampleBegin(StgInt era, StgWord64 time)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, EVENT_HEAP_BIO_PROF_SAMPLE_BEGIN);
    postEventHeader(&eventBuf, EVENT_HEAP_BIO_PROF_SAMPLE_BEGIN);
    postWord64(&eventBuf, era);
    postWord64(&eventBuf, time);
    RELEASE_LOCK(&eventBufMutex);
}

void postHeapProfSampleEnd(StgInt era)
{
    ACQUIRE_LOCK(&eventBufMutex);
    ensureRoomForEvent(&eventBuf, EVENT_HEAP_PROF_SAMPLE_END);
    postEventHeader(&eventBuf, EVENT_HEAP_PROF_SAMPLE_END);
    postWord64(&eventBuf, era);
    RELEASE_LOCK(&eventBufMutex);
}

void postHeapProfSampleString(StgWord8 profile_id,
                              const char *label,
                              StgWord64 residency)
{
    ACQUIRE_LOCK(&eventBufMutex);
    StgWord label_len = strlen(label);
    StgWord len = 1+8+label_len+1;
    ensureRoomForVariableEvent(&eventBuf, len);
    postEventHeader(&eventBuf, EVENT_HEAP_PROF_SAMPLE_STRING);
    postPayloadSize(&eventBuf, len);
    postWord8(&eventBuf, profile_id);
    postWord64(&eventBuf, residency);
    postString(&eventBuf, label);
    RELEASE_LOCK(&eventBufMutex);
}

#if defined(PROFILING)
void postHeapProfCostCentre(StgWord32 ccID,
                            const char *label,
                            const char *module,
                            const char *srcloc,
                            StgBool is_caf)
{
    ACQUIRE_LOCK(&eventBufMutex);
    StgWord label_len = strlen(label);
    StgWord module_len = strlen(module);
    StgWord srcloc_len = strlen(srcloc);
    StgWord len = 4+label_len+module_len+srcloc_len+3+1;
    ensureRoomForVariableEvent(&eventBuf, len);
    postEventHeader(&eventBuf, EVENT_HEAP_PROF_COST_CENTRE);
    postPayloadSize(&eventBuf, len);
    postWord32(&eventBuf, ccID);
    postString(&eventBuf, label);
    postString(&eventBuf, module);
    postString(&eventBuf, srcloc);
    postWord8(&eventBuf, is_caf);
    RELEASE_LOCK(&eventBufMutex);
}

void postHeapProfSampleCostCentre(StgWord8 profile_id,
                                  CostCentreStack *stack,
                                  StgWord64 residency)
{
    ACQUIRE_LOCK(&eventBufMutex);
    StgWord depth = 0;
    CostCentreStack *ccs;
    for (ccs = stack; ccs != NULL && ccs != CCS_MAIN; ccs = ccs->prevStack)
        depth++;
    if (depth > 0xff) depth = 0xff;

    StgWord len = 1+8+1+depth*4;
    ensureRoomForVariableEvent(&eventBuf, len);
    postEventHeader(&eventBuf, EVENT_HEAP_PROF_SAMPLE_COST_CENTRE);
    postPayloadSize(&eventBuf, len);
    postWord8(&eventBuf, profile_id);
    postWord64(&eventBuf, residency);
    postWord8(&eventBuf, depth);
    for (ccs = stack;
         depth>0 && ccs != NULL && ccs != CCS_MAIN;
         ccs = ccs->prevStack, depth--)
        postWord32(&eventBuf, ccs->cc->ccID);
    RELEASE_LOCK(&eventBufMutex);
}
#endif /* PROFILING */

void printAndClearEventBuf (EventsBuf *ebuf)
{
    closeBlockMarker(ebuf);

    if (ebuf->begin != NULL && ebuf->pos != ebuf->begin)
    {
        size_t elog_size = ebuf->pos - ebuf->begin;
        if (!writeEventLog(ebuf->begin, elog_size)) {
            debugBelch(
                    "printAndClearEventLog: could not flush event log"
                );
            resetEventsBuf(ebuf);
            return;
        }

        resetEventsBuf(ebuf);
        flushCount++;

        postBlockMarker(ebuf);
    }
}

void initEventsBuf(EventsBuf* eb, StgWord64 size, EventCapNo capno)
{
    eb->begin = eb->pos = stgMallocBytes(size, "initEventsBuf");
    eb->size = size;
    eb->marker = NULL;
    eb->capno = capno;
}

void resetEventsBuf(EventsBuf* eb)
{
    eb->pos = eb->begin;
    eb->marker = NULL;
}

StgBool hasRoomForEvent(EventsBuf *eb, EventTypeNum eNum)
{
  uint32_t size = sizeof(EventTypeNum) + sizeof(EventTimestamp) + eventTypes[eNum].size;

  if (eb->pos + size > eb->begin + eb->size) {
      return 0; // Not enough space.
  } else  {
      return 1; // Buf has enough space for the event.
  }
}

StgBool hasRoomForVariableEvent(EventsBuf *eb, uint32_t payload_bytes)
{
  uint32_t size = sizeof(EventTypeNum) + sizeof(EventTimestamp) +
      sizeof(EventPayloadSize) + payload_bytes;

  if (eb->pos + size > eb->begin + eb->size) {
      return 0; // Not enough space.
  } else  {
      return 1; // Buf has enough space for the event.
  }
}

void ensureRoomForEvent(EventsBuf *eb, EventTypeNum tag)
{
    if (!hasRoomForEvent(eb, tag)) {
        // Flush event buffer to make room for new event.
        printAndClearEventBuf(eb);
    }
}

int ensureRoomForVariableEvent(EventsBuf *eb, StgWord16 size)
{
    if (!hasRoomForVariableEvent(eb, size)) {
        // Flush event buffer to make room for new event.
        printAndClearEventBuf(eb);
        if (!hasRoomForVariableEvent(eb, size))
            return 1; // Not enough space
    }
    return 0;
}


void postEventType(EventsBuf *eb, EventType *et)
{
    postInt32(eb, EVENT_ET_BEGIN);
    postEventTypeNum(eb, et->etNum);
    postWord16(eb, (StgWord16)et->size);
    const int desclen = strlen(et->desc);
    postWord32(eb, desclen);
    for (int d = 0; d < desclen; ++d) {
        postInt8(eb, (StgInt8)et->desc[d]);
    }
    postWord32(eb, 0); // no extensions yet
    postInt32(eb, EVENT_ET_END);
}

#endif /* TRACING */