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
|
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>DB_ENV->set_event_notify()</title>
<link rel="stylesheet" href="apiReference.css" type="text/css" />
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
<link rel="start" href="index.html" title="Berkeley DB C API Reference" />
<link rel="up" href="env.html" title="Chapter 5. The DB_ENV Handle" />
<link rel="prev" href="envset_encrypt.html" title="DB_ENV->set_encrypt()" />
<link rel="next" href="envset_errcall.html" title="DB_ENV->set_errcall()" />
</head>
<body>
<div xmlns="" class="navheader">
<div class="libver">
<p>Library Version 12.1.6.1</p>
</div>
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">DB_ENV->set_event_notify()</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="envset_encrypt.html">Prev</a> </td>
<th width="60%" align="center">Chapter 5.
The DB_ENV Handle
</th>
<td width="20%" align="right"> <a accesskey="n" href="envset_errcall.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="envevent_notify"></a>DB_ENV->set_event_notify()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db.h>
int
DB_ENV->set_event_notify(DB_ENV *dbenv,
void (*db_event_fcn)(DB_ENV *dbenv, u_int32_t event,
void *event_info)); </pre>
<p>
The <code class="methodname">DB_ENV->set_event_notify()</code> method
configures a callback function which is called to notify the
process of specific Berkeley DB events.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
Berkeley DB is not re-entrant. Callback functions should
not attempt to make library calls (for example, to release
locks or close open handles). Re-entering Berkeley DB is
not guaranteed to work correctly, and the results are
undefined.
</p>
</div>
<p>
The <code class="methodname">DB_ENV->set_event_notify()</code> method
configures operations performed using the specified
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handle, not all operations
performed on the underlying database environment.
</p>
<p>
The <code class="methodname">DB_ENV->set_event_notify()</code> method may
be called at any time during the life of the application.
</p>
<p>
The <code class="methodname">DB_ENV->set_event_notify()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp1484248"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp1468880"></a>db_event_fcn</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>db_event_fcn</strong></span> parameter is the
application's event notification function. The function takes three
parameters:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<code class="literal">dbenv</code>
</p>
<p>
The <span class="bold"><strong>dbenv</strong></span>
parameter is the enclosing database environment
handle.
</p>
</li>
<li>
<p>
<code class="literal">event</code>
</p>
<p>
The <span class="bold"><strong>event</strong></span> parameter is one of the
following values:
</p>
<div class="itemizedlist">
<ul type="circle">
<li>
<p><a id="event_notify_DB_EVENT_FAILCHK_PANIC"></a>
<code class="literal">DB_EVENT_FAILCHK_PANIC</code>
</p>
<p>
The thread is about to return a
<a href="../../programmer_reference/program_errorret.html#program_errorret.DB_RUNRECOVERY" class="olink">
DB_RUNRECOVERY
</a>
error because a prior panic event has occurred and the
thread has been marked by <a class="xref" href="envfailchk.html" title="DB_ENV->failchk()">DB_ENV->failchk()</a> as being held by a
crashed process.
</p>
<p>
The <span class="bold"><strong>event_info</strong></span> parameter
is a pointer to a <code class="literal">DB_FAILCHK_PANIC_INFO</code>
structure, which contains these fields:
</p>
<pre class="programlisting">int error;
char symptom[DB_FAILURE_SYMPTOM_SIZE];</pre>
<p>
When this event is seen, the database environment has
failed. All threads of control in the database environment
should exit, and recovery should be run.
</p>
<p>
This event is generated only when failchk broadcasting is
configured. You configured broadcasting by
specifying
<code class="literal">--enable-failchk_broadcast</code>
when you compile your Berkeley DB library.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_MUTEX_DIED"></a>
<code class="literal">DB_EVENT_MUTEX_DIED</code>
</p>
<p>
The thread is about to return a
<a href="../../programmer_reference/program_errorret.html#program_errorret.DB_RUNRECOVERY" class="olink">
DB_RUNRECOVERY
</a>
error because a mutex it requires has been
marked by <a class="xref" href="envfailchk.html" title="DB_ENV->failchk()">DB_ENV->failchk()</a> as being held by a
crashed process.
</p>
<p>
The <span class="bold"><strong>event_info</strong></span> parameter
is a pointer to a <code class="literal">DB_MUTEX_DIED_INFO</code>
structure, which contains these fields:
</p>
<pre class="programlisting"> pid_t mtxdied_pid;
db_threadid_t mtxdied_tid;
db_mutex_t mtxdied_mtx;
char mtxdied_desc[DB_MUTEX_DESCRIBE_STRLEN]; </pre>
<p>
When this event is seen, the database environment has
failed. All threads of control in the database environment
should exit, and recovery should be run.
</p>
<p>
This event is generated only when failchk broadcasting is
configured. You configured broadcasting by
specifying
<code class="literal">--enable-failchk_broadcast</code>
when you compile your Berkeley DB library.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_PANIC"></a>
<code class="literal">DB_EVENT_PANIC</code>
</p>
<p>
Errors can occur in the Berkeley DB library where the only solution
is to shut down the application and run recovery (for example, if
Berkeley DB is unable to allocate heap memory). In such cases, the
Berkeley DB methods will return
<a href="../../programmer_reference/program_errorret.html#program_errorret.DB_RUNRECOVERY" class="olink">DB_RUNRECOVERY</a>.
It is often easier to simply exit the application when such errors
occur rather than gracefully return up the stack.
</p>
<p>
When <span class="bold"><strong>event</strong></span> is set to
<code class="literal">DB_EVENT_PANIC</code>, the database environment has
failed. All threads of control in the database environment should
exit the environment, and recovery should be run.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REG_ALIVE"></a>
<code class="literal">DB_EVENT_REG_ALIVE</code>
</p>
<p>
Recovery is needed in an environment where the
<a class="link" href="envopen.html#envopen_DB_REGISTER">DB_REGISTER</a>
flag was specified on the
<a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> method and there is
a process attached to the environment. The callback function is triggered
once for each process attached.
</p>
<p>
The <span class="bold"><strong>event_info</strong></span> parameter points to a pid_t value
containing the process identifier (pid) of the process the Berkeley DB library
detects is attached to the environment.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REG_PANIC"></a>
<code class="literal">DB_EVENT_REG_PANIC</code>
</p>
<p>
Recovery is needed in an environment where the
<a class="link" href="envopen.html#envopen_DB_REGISTER">DB_REGISTER</a>
flag was specified
on the <a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> method. All threads
of control in the database environment should exit the environment.
</p>
<p>
This event is different than the <code class="literal">DB_EVENT_PANIC</code> event
because it can only be triggered when <code class="literal">DB_REGISTER</code> was
specified. It can be used to distinguish between the case when a process
dies in the environment and recovery is initiated versus the case when an
error happened (for example, if Berkeley DB is unable to allocate heap
memory)
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_AUTOTAKEOVER_FAILED"></a>
<code class="literal">DB_EVENT_REP_AUTOTAKEOVER_FAILED</code>
</p>
<p>
The current subordinate process attempted to
take over as the replication process, but
the attempt failed.
</p>
<p>
The replication process is the main Replication Manager process
which is responsible for sending and processing most Replication
Manager messages. Normally this is the first process started in a
replication group, but when that process shuts down cleanly, a
subordinate process will take over if one is available.
</p>
<p>
This event means that this Replication Manager subordinate process
attempted to take over as the replication process, but it failed.
Replication Manager is not running locally but may be restarted by
invoking <a class="xref" href="repmgrstart.html" title="DB_ENV->repmgr_start()">DB_ENV->repmgr_start()</a>.
</p>
<p>
The <code class="literal">DB_EVENT_REP_AUTOTAKEOVER_FAILED</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_CLIENT"></a>
<code class="literal">DB_EVENT_REP_CLIENT</code>
</p>
<p>
The local site is now a replication client.
</p>
<p>
This event is generated when the replication role changes to client,
either from master or from being unset. The role is unset when an
environment is first created and after an environment is recovered.
This event is not generated when restarting replication in an
environment that was previously a client and was opened without
recovery.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_CONNECT_BROKEN"></a>
<code class="literal">DB_EVENT_REP_CONNECT_BROKEN</code>
</p>
<p>
A previously established Replication Manager message connection between the
local site and a remote site has been broken. This event supplies
the EID of the remote site, and an integer error code that
identifies the reason the connection was broken.
</p>
<p>
A non-zero error code indicates an unexpected
condition such as a hardware failure or a
protocol error. An application might respond
by emitting an informational message or passing
this information to other parts of the
application using the
<code class="literal">app_private</code>
field. A zero error code indicates that the
connection was cleanly closed by the other end.
Replication Manager retries broken connections
periodically until they are restored.
</p>
<p>
The <code class="literal">DB_EVENT_REP_CONNECT_BROKEN</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_CONNECT_ESTD"></a>
<code class="literal">DB_EVENT_REP_CONNECT_ESTD</code>
</p>
<p>
A Replication Manager message connection has been established between the
local site and a remote site. This event supplied the EID of the
remote site.
</p>
<p>
The <code class="literal">DB_EVENT_REP_CONNECT_ESTD</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_CONNECT_TRY_FAILED"></a>
<code class="literal">DB_EVENT_REP_CONNECT_TRY_FAILED</code>
</p>
<p>
A Replication Manager attempt to establish a connection between the local site and a
remote site has failed. This event supplies the EID of the remote
site, and an integer error code that identifies the reason the
connection attempt failed.
</p>
<p>
The <code class="literal">DB_EVENT_REP_CONNECT_TRY_FAILED</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_DUPMASTER"></a>
<code class="literal">DB_EVENT_REP_DUPMASTER</code>
</p>
<p>
Replication Manager has detected a duplicate master situation, and
has changed the local site to the client role as a result. If the
<a class="link" href="repconfig.html#config_DB_REPMGR_CONF_ELECTIONS">DB_REPMGR_CONF_ELECTIONS</a>
configuration parameter has been turned off, the application should
now choose and assign the correct master site. If
<code class="literal">DB_REPMGR_CONF_ELECTIONS</code> is turned on, the
application may ignore this event.
</p>
<p>
The <code class="literal">DB_EVENT_REP_DUPMASTER</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_ELECTED"></a>
<code class="literal">DB_EVENT_REP_ELECTED</code>
</p>
<p>
The local replication site has just won an election. A
Base API application should call the
<a class="xref" href="repstart.html" title="DB_ENV->rep_start()">DB_ENV->rep_start()</a> method
after receiving this event, to reconfigure the local environment as a
replication master.
</p>
<p>
Replication Manager applications may safely ignore this event. The
Replication Manager calls <a class="xref" href="repstart.html" title="DB_ENV->rep_start()">DB_ENV->rep_start()</a>
automatically on behalf of the application when appropriate (resulting
in firing of the DB_EVENT_REP_MASTER event).
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_ELECTION_FAILED"></a>
<code class="literal">DB_EVENT_REP_ELECTION_FAILED</code>
</p>
<p>
Replication Manager tried to run an election to choose a master
site, but the election failed due to lack of timely participation by
a sufficient number of other sites. Replication Manager will
automatically retry the election later. This event is for
information only.
</p>
<p>
The <code class="literal">DB_EVENT_REP_ELECTION_FAILED</code> event is
provided only to applications configured for the Replication
Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_INIT_DONE"></a>
<code class="literal">DB_EVENT_REP_INIT_DONE</code>
</p>
<p>
The local client site has completed an
internal initialization procedure.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_INQUEUE_FULL"></a>
<code class="literal">DB_EVENT_REP_INQUEUE_FULL</code>
</p>
<p>
Incoming messages will be dropped because the Replication Mananger
incoming queue has reached its maximum threshold.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_JOIN_FAILURE"></a>
<code class="literal">DB_EVENT_REP_JOIN_FAILURE</code>
</p>
<p>
The local client site is unable to synchronize with a new master,
possibly because the client has turned off automatic internal
initialization by setting the
<a class="link" href="repconfig.html#config_DB_REP_CONF_AUTOINIT">DB_REP_CONF_AUTOINIT</a>
flag to <code class="literal">0</code>.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_LOCAL_SITE_REMOVED"></a>
<code class="literal">DB_EVENT_REP_LOCAL_SITE_REMOVED</code>
</p>
<p>
The local site has been
removed from the replication group.
</p>
<p>
The <code class="literal">DB_EVENT_REP_LOCAL_SITE_REMOVED</code> event is
provided only to applications configured for the Replication
Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_MASTER"></a>
<code class="literal">DB_EVENT_REP_MASTER</code>
</p>
<p>
The local site is now the master site of its replication group. It is
the application's responsibility to begin acting as the master
environment.
</p>
<p>
This event is generated when the replication role changes to master,
either from client or from being unset. The role is unset when an
environment is first created and after an environment is recovered.
This event is not generated when restarting replication in an
environment that was previously a master and was opened without
recovery.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_MASTER_FAILURE"></a>
<code class="literal">DB_EVENT_REP_MASTER_FAILURE</code>
</p>
<p>
A Replication Manager client site has detected the loss of
connection to the master site. If the
<a class="link" href="repconfig.html#config_DB_REPMGR_CONF_ELECTIONS">DB_REPMGR_CONF_ELECTIONS</a>
configuration parameter is turned on, Replication Manager will
automatically start an election in order to choose a new master. In
this case, this event may be ignored.
</p>
<p>
When <code class="literal">DB_REPMGR_CONF_ELECTIONS</code> is turned off, the
application should choose and assign a new master. Failure to do so
means that your replication group has no master, and so it cannot
service write requests.
</p>
<p>
The <code class="literal">DB_EVENT_REP_MASTER_FAILURE</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_NEWMASTER"></a>
<code class="literal">DB_EVENT_REP_NEWMASTER</code>
</p>
<p>
The replication group of which this site is a member has just
established a new master; the local site is not the new master. The
<span class="bold"><strong>event_info</strong></span> parameter points to an
integer containing the environment ID of the new master.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_PERM_FAILED"></a>
<code class="literal">DB_EVENT_REP_PERM_FAILED</code>
</p>
<p>
The Replication Manager did not receive enough acknowledgements (based
on the acknowledgement policy configured with
<a class="xref" href="repmgrset_ack_policy.html" title="DB_ENV->repmgr_set_ack_policy()">DB_ENV->repmgr_set_ack_policy()</a> )
to ensure a transaction's durability within the replication group.
The transaction will be flushed to the master's local disk storage for
durability.
</p>
<p>
The <code class="literal">DB_EVENT_REP_PERM_FAILED</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_SITE_ADDED"></a>
<code class="literal">DB_EVENT_REP_SITE_ADDED</code>
</p>
<p>
A new site has joined the replication group.
The
<span class="bold"><strong>event_info</strong></span> parameter points to an
integer containing the environment ID of the new site.
</p>
<p>
The <code class="literal">DB_EVENT_REP_SITE_ADDED</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_SITE_REMOVED"></a>
<code class="literal">DB_EVENT_REP_SITE_REMOVED</code>
</p>
<p>
An existing remote site has been removed from the replication group. The
<span class="bold"><strong>event_info</strong></span> parameter points to an
integer containing the environment ID of the site that was removed.
</p>
<p>
The <code class="literal">DB_EVENT_REP_SITE_REOMVED</code> event is provided
only to applications configured for the Replication Manager.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_REP_STARTUPDONE"></a>
<code class="literal">DB_EVENT_REP_STARTUPDONE</code>
</p>
<p>
The replication client has completed startup synchronization and is now processing
live log records received from the master.
</p>
</li>
<li>
<p><a id="event_notify_DB_EVENT_WRITE_FAILED"></a>
<code class="literal">DB_EVENT_WRITE_FAILED</code>
</p>
<p>
A Berkeley DB write to stable storage failed.
</p>
</li>
</ul>
</div>
</li>
<li>
<p>
<code class="literal">event_info</code>
</p>
<p>
The <span class="bold"><strong>event_info</strong></span> parameter may
reference memory which contains additional information describing an
event. By default, <span class="bold"><strong>event_info</strong></span> is
NULL; specific events may pass non-NULL values, in which case the
event will also describe the memory's structure.
</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp1552976"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp1538680"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a>
</p>
</div>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="envset_encrypt.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="env.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="envset_errcall.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">DB_ENV->set_encrypt() </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> DB_ENV->set_errcall()</td>
</tr>
</table>
</div>
</body>
</html>
|
