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
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<link rel="stylesheet" href="style.css" type="text/css">
<meta content="text/html; charset=iso-8859-1" http-equiv="Content-Type">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="Start" href="index.html">
<link rel="previous" href="Netplex_semaphore.html">
<link rel="next" href="Netplex_mutex.html">
<link rel="Up" href="index.html">
<link title="Index of types" rel=Appendix href="index_types.html">
<link title="Index of extensions" rel=Appendix href="index_extensions.html">
<link title="Index of exceptions" rel=Appendix href="index_exceptions.html">
<link title="Index of values" rel=Appendix href="index_values.html">
<link title="Index of class attributes" rel=Appendix href="index_attributes.html">
<link title="Index of class methods" rel=Appendix href="index_methods.html">
<link title="Index of classes" rel=Appendix href="index_classes.html">
<link title="Index of class types" rel=Appendix href="index_class_types.html">
<link title="Index of modules" rel=Appendix href="index_modules.html">
<link title="Index of module types" rel=Appendix href="index_module_types.html">
<link title="Uq_gtk" rel="Chapter" href="Uq_gtk.html">
<link title="Uq_tcl" rel="Chapter" href="Uq_tcl.html">
<link title="Equeue" rel="Chapter" href="Equeue.html">
<link title="Unixqueue" rel="Chapter" href="Unixqueue.html">
<link title="Unixqueue_pollset" rel="Chapter" href="Unixqueue_pollset.html">
<link title="Unixqueue_select" rel="Chapter" href="Unixqueue_select.html">
<link title="Uq_resolver" rel="Chapter" href="Uq_resolver.html">
<link title="Uq_engines" rel="Chapter" href="Uq_engines.html">
<link title="Uq_multiplex" rel="Chapter" href="Uq_multiplex.html">
<link title="Uq_transfer" rel="Chapter" href="Uq_transfer.html">
<link title="Uq_socks5" rel="Chapter" href="Uq_socks5.html">
<link title="Uq_io" rel="Chapter" href="Uq_io.html">
<link title="Uq_lwt" rel="Chapter" href="Uq_lwt.html">
<link title="Uq_libevent" rel="Chapter" href="Uq_libevent.html">
<link title="Uq_mt" rel="Chapter" href="Uq_mt.html">
<link title="Uq_client" rel="Chapter" href="Uq_client.html">
<link title="Uq_server" rel="Chapter" href="Uq_server.html">
<link title="Uq_datagram" rel="Chapter" href="Uq_datagram.html">
<link title="Uq_engines_compat" rel="Chapter" href="Uq_engines_compat.html">
<link title="Equeue_intro" rel="Chapter" href="Equeue_intro.html">
<link title="Equeue_howto" rel="Chapter" href="Equeue_howto.html">
<link title="Netcamlbox" rel="Chapter" href="Netcamlbox.html">
<link title="Netcgi_apache" rel="Chapter" href="Netcgi_apache.html">
<link title="Netcgi_modtpl" rel="Chapter" href="Netcgi_modtpl.html">
<link title="Netcgi_plex" rel="Chapter" href="Netcgi_plex.html">
<link title="Netcgi_common" rel="Chapter" href="Netcgi_common.html">
<link title="Netcgi" rel="Chapter" href="Netcgi.html">
<link title="Netcgi_ajp" rel="Chapter" href="Netcgi_ajp.html">
<link title="Netcgi_scgi" rel="Chapter" href="Netcgi_scgi.html">
<link title="Netcgi_cgi" rel="Chapter" href="Netcgi_cgi.html">
<link title="Netcgi_fcgi" rel="Chapter" href="Netcgi_fcgi.html">
<link title="Netcgi_dbi" rel="Chapter" href="Netcgi_dbi.html">
<link title="Netcgi1_compat" rel="Chapter" href="Netcgi1_compat.html">
<link title="Netcgi_test" rel="Chapter" href="Netcgi_test.html">
<link title="Netcgi_porting" rel="Chapter" href="Netcgi_porting.html">
<link title="Nethttp_client_conncache" rel="Chapter" href="Nethttp_client_conncache.html">
<link title="Nethttp_client" rel="Chapter" href="Nethttp_client.html">
<link title="Nettelnet_client" rel="Chapter" href="Nettelnet_client.html">
<link title="Netftp_data_endpoint" rel="Chapter" href="Netftp_data_endpoint.html">
<link title="Netftp_client" rel="Chapter" href="Netftp_client.html">
<link title="Nethttp_fs" rel="Chapter" href="Nethttp_fs.html">
<link title="Netftp_fs" rel="Chapter" href="Netftp_fs.html">
<link title="Netsmtp" rel="Chapter" href="Netsmtp.html">
<link title="Netpop" rel="Chapter" href="Netpop.html">
<link title="Netldap" rel="Chapter" href="Netldap.html">
<link title="Netclient_tut" rel="Chapter" href="Netclient_tut.html">
<link title="Netgss_bindings" rel="Chapter" href="Netgss_bindings.html">
<link title="Netgss" rel="Chapter" href="Netgss.html">
<link title="Nethttpd_types" rel="Chapter" href="Nethttpd_types.html">
<link title="Nethttpd_kernel" rel="Chapter" href="Nethttpd_kernel.html">
<link title="Nethttpd_reactor" rel="Chapter" href="Nethttpd_reactor.html">
<link title="Nethttpd_engine" rel="Chapter" href="Nethttpd_engine.html">
<link title="Nethttpd_services" rel="Chapter" href="Nethttpd_services.html">
<link title="Nethttpd_plex" rel="Chapter" href="Nethttpd_plex.html">
<link title="Nethttpd_util" rel="Chapter" href="Nethttpd_util.html">
<link title="Nethttpd_intro" rel="Chapter" href="Nethttpd_intro.html">
<link title="Netmcore" rel="Chapter" href="Netmcore.html">
<link title="Netmcore_camlbox" rel="Chapter" href="Netmcore_camlbox.html">
<link title="Netmcore_mempool" rel="Chapter" href="Netmcore_mempool.html">
<link title="Netmcore_heap" rel="Chapter" href="Netmcore_heap.html">
<link title="Netmcore_ref" rel="Chapter" href="Netmcore_ref.html">
<link title="Netmcore_array" rel="Chapter" href="Netmcore_array.html">
<link title="Netmcore_sem" rel="Chapter" href="Netmcore_sem.html">
<link title="Netmcore_mutex" rel="Chapter" href="Netmcore_mutex.html">
<link title="Netmcore_condition" rel="Chapter" href="Netmcore_condition.html">
<link title="Netmcore_queue" rel="Chapter" href="Netmcore_queue.html">
<link title="Netmcore_buffer" rel="Chapter" href="Netmcore_buffer.html">
<link title="Netmcore_matrix" rel="Chapter" href="Netmcore_matrix.html">
<link title="Netmcore_hashtbl" rel="Chapter" href="Netmcore_hashtbl.html">
<link title="Netmcore_process" rel="Chapter" href="Netmcore_process.html">
<link title="Netmcore_tut" rel="Chapter" href="Netmcore_tut.html">
<link title="Netmcore_basics" rel="Chapter" href="Netmcore_basics.html">
<link title="Netplex_types" rel="Chapter" href="Netplex_types.html">
<link title="Netplex_mp" rel="Chapter" href="Netplex_mp.html">
<link title="Netplex_mt" rel="Chapter" href="Netplex_mt.html">
<link title="Netplex_log" rel="Chapter" href="Netplex_log.html">
<link title="Netplex_controller" rel="Chapter" href="Netplex_controller.html">
<link title="Netplex_container" rel="Chapter" href="Netplex_container.html">
<link title="Netplex_sockserv" rel="Chapter" href="Netplex_sockserv.html">
<link title="Netplex_workload" rel="Chapter" href="Netplex_workload.html">
<link title="Netplex_main" rel="Chapter" href="Netplex_main.html">
<link title="Netplex_config" rel="Chapter" href="Netplex_config.html">
<link title="Netplex_kit" rel="Chapter" href="Netplex_kit.html">
<link title="Rpc_netplex" rel="Chapter" href="Rpc_netplex.html">
<link title="Netplex_cenv" rel="Chapter" href="Netplex_cenv.html">
<link title="Netplex_semaphore" rel="Chapter" href="Netplex_semaphore.html">
<link title="Netplex_sharedvar" rel="Chapter" href="Netplex_sharedvar.html">
<link title="Netplex_mutex" rel="Chapter" href="Netplex_mutex.html">
<link title="Netplex_encap" rel="Chapter" href="Netplex_encap.html">
<link title="Netplex_mbox" rel="Chapter" href="Netplex_mbox.html">
<link title="Netplex_internal" rel="Chapter" href="Netplex_internal.html">
<link title="Netplex_intro" rel="Chapter" href="Netplex_intro.html">
<link title="Netplex_advanced" rel="Chapter" href="Netplex_advanced.html">
<link title="Netplex_admin" rel="Chapter" href="Netplex_admin.html">
<link title="Netshm" rel="Chapter" href="Netshm.html">
<link title="Netshm_data" rel="Chapter" href="Netshm_data.html">
<link title="Netshm_hashtbl" rel="Chapter" href="Netshm_hashtbl.html">
<link title="Netshm_array" rel="Chapter" href="Netshm_array.html">
<link title="Netshm_intro" rel="Chapter" href="Netshm_intro.html">
<link title="Netstring_pcre" rel="Chapter" href="Netstring_pcre.html">
<link title="Netconversion" rel="Chapter" href="Netconversion.html">
<link title="Netchannels" rel="Chapter" href="Netchannels.html">
<link title="Netstream" rel="Chapter" href="Netstream.html">
<link title="Netmime_string" rel="Chapter" href="Netmime_string.html">
<link title="Netmime" rel="Chapter" href="Netmime.html">
<link title="Netsendmail" rel="Chapter" href="Netsendmail.html">
<link title="Neturl" rel="Chapter" href="Neturl.html">
<link title="Netaddress" rel="Chapter" href="Netaddress.html">
<link title="Netbuffer" rel="Chapter" href="Netbuffer.html">
<link title="Netmime_header" rel="Chapter" href="Netmime_header.html">
<link title="Netmime_channels" rel="Chapter" href="Netmime_channels.html">
<link title="Neturl_ldap" rel="Chapter" href="Neturl_ldap.html">
<link title="Netdate" rel="Chapter" href="Netdate.html">
<link title="Netencoding" rel="Chapter" href="Netencoding.html">
<link title="Netulex" rel="Chapter" href="Netulex.html">
<link title="Netaccel" rel="Chapter" href="Netaccel.html">
<link title="Netaccel_link" rel="Chapter" href="Netaccel_link.html">
<link title="Nethtml" rel="Chapter" href="Nethtml.html">
<link title="Netstring_str" rel="Chapter" href="Netstring_str.html">
<link title="Netmappings" rel="Chapter" href="Netmappings.html">
<link title="Netaux" rel="Chapter" href="Netaux.html">
<link title="Nethttp" rel="Chapter" href="Nethttp.html">
<link title="Netpagebuffer" rel="Chapter" href="Netpagebuffer.html">
<link title="Netfs" rel="Chapter" href="Netfs.html">
<link title="Netglob" rel="Chapter" href="Netglob.html">
<link title="Netauth" rel="Chapter" href="Netauth.html">
<link title="Netsockaddr" rel="Chapter" href="Netsockaddr.html">
<link title="Netnumber" rel="Chapter" href="Netnumber.html">
<link title="Netxdr_mstring" rel="Chapter" href="Netxdr_mstring.html">
<link title="Netxdr" rel="Chapter" href="Netxdr.html">
<link title="Netcompression" rel="Chapter" href="Netcompression.html">
<link title="Netunichar" rel="Chapter" href="Netunichar.html">
<link title="Netasn1" rel="Chapter" href="Netasn1.html">
<link title="Netasn1_encode" rel="Chapter" href="Netasn1_encode.html">
<link title="Netoid" rel="Chapter" href="Netoid.html">
<link title="Netstring_tstring" rel="Chapter" href="Netstring_tstring.html">
<link title="Netdn" rel="Chapter" href="Netdn.html">
<link title="Netx509" rel="Chapter" href="Netx509.html">
<link title="Netascii_armor" rel="Chapter" href="Netascii_armor.html">
<link title="Nettls_support" rel="Chapter" href="Nettls_support.html">
<link title="Netmech_scram" rel="Chapter" href="Netmech_scram.html">
<link title="Netmech_scram_gssapi" rel="Chapter" href="Netmech_scram_gssapi.html">
<link title="Netmech_scram_sasl" rel="Chapter" href="Netmech_scram_sasl.html">
<link title="Netmech_scram_http" rel="Chapter" href="Netmech_scram_http.html">
<link title="Netgssapi_support" rel="Chapter" href="Netgssapi_support.html">
<link title="Netgssapi_auth" rel="Chapter" href="Netgssapi_auth.html">
<link title="Netchannels_crypto" rel="Chapter" href="Netchannels_crypto.html">
<link title="Netx509_pubkey" rel="Chapter" href="Netx509_pubkey.html">
<link title="Netx509_pubkey_crypto" rel="Chapter" href="Netx509_pubkey_crypto.html">
<link title="Netsaslprep" rel="Chapter" href="Netsaslprep.html">
<link title="Netmech_plain_sasl" rel="Chapter" href="Netmech_plain_sasl.html">
<link title="Netmech_crammd5_sasl" rel="Chapter" href="Netmech_crammd5_sasl.html">
<link title="Netmech_digest_sasl" rel="Chapter" href="Netmech_digest_sasl.html">
<link title="Netmech_digest_http" rel="Chapter" href="Netmech_digest_http.html">
<link title="Netmech_krb5_sasl" rel="Chapter" href="Netmech_krb5_sasl.html">
<link title="Netmech_gs2_sasl" rel="Chapter" href="Netmech_gs2_sasl.html">
<link title="Netmech_spnego_http" rel="Chapter" href="Netmech_spnego_http.html">
<link title="Netchannels_tut" rel="Chapter" href="Netchannels_tut.html">
<link title="Netmime_tut" rel="Chapter" href="Netmime_tut.html">
<link title="Netsendmail_tut" rel="Chapter" href="Netsendmail_tut.html">
<link title="Netulex_tut" rel="Chapter" href="Netulex_tut.html">
<link title="Neturl_tut" rel="Chapter" href="Neturl_tut.html">
<link title="Netsys" rel="Chapter" href="Netsys.html">
<link title="Netsys_posix" rel="Chapter" href="Netsys_posix.html">
<link title="Netsys_pollset" rel="Chapter" href="Netsys_pollset.html">
<link title="Netlog" rel="Chapter" href="Netlog.html">
<link title="Netexn" rel="Chapter" href="Netexn.html">
<link title="Netsys_win32" rel="Chapter" href="Netsys_win32.html">
<link title="Netsys_pollset_posix" rel="Chapter" href="Netsys_pollset_posix.html">
<link title="Netsys_pollset_win32" rel="Chapter" href="Netsys_pollset_win32.html">
<link title="Netsys_pollset_generic" rel="Chapter" href="Netsys_pollset_generic.html">
<link title="Netsys_signal" rel="Chapter" href="Netsys_signal.html">
<link title="Netsys_oothr" rel="Chapter" href="Netsys_oothr.html">
<link title="Netsys_xdr" rel="Chapter" href="Netsys_xdr.html">
<link title="Netsys_rng" rel="Chapter" href="Netsys_rng.html">
<link title="Netsys_crypto_types" rel="Chapter" href="Netsys_crypto_types.html">
<link title="Netsys_types" rel="Chapter" href="Netsys_types.html">
<link title="Netsys_mem" rel="Chapter" href="Netsys_mem.html">
<link title="Netsys_tmp" rel="Chapter" href="Netsys_tmp.html">
<link title="Netsys_sem" rel="Chapter" href="Netsys_sem.html">
<link title="Netsys_pmanage" rel="Chapter" href="Netsys_pmanage.html">
<link title="Netsys_crypto" rel="Chapter" href="Netsys_crypto.html">
<link title="Netsys_tls" rel="Chapter" href="Netsys_tls.html">
<link title="Netsys_ciphers" rel="Chapter" href="Netsys_ciphers.html">
<link title="Netsys_digests" rel="Chapter" href="Netsys_digests.html">
<link title="Netsys_crypto_modes" rel="Chapter" href="Netsys_crypto_modes.html">
<link title="Netsys_gssapi" rel="Chapter" href="Netsys_gssapi.html">
<link title="Netsys_sasl_types" rel="Chapter" href="Netsys_sasl_types.html">
<link title="Netsys_sasl" rel="Chapter" href="Netsys_sasl.html">
<link title="Netsys_polypipe" rel="Chapter" href="Netsys_polypipe.html">
<link title="Netsys_polysocket" rel="Chapter" href="Netsys_polysocket.html">
<link title="Netsys_global" rel="Chapter" href="Netsys_global.html">
<link title="Nettls_gnutls_bindings" rel="Chapter" href="Nettls_gnutls_bindings.html">
<link title="Nettls_nettle_bindings" rel="Chapter" href="Nettls_nettle_bindings.html">
<link title="Nettls_gnutls" rel="Chapter" href="Nettls_gnutls.html">
<link title="Netunidata" rel="Chapter" href="Netunidata.html">
<link title="Netgzip" rel="Chapter" href="Netgzip.html">
<link title="Rpc_auth_local" rel="Chapter" href="Rpc_auth_local.html">
<link title="Rpc_xti_client" rel="Chapter" href="Rpc_xti_client.html">
<link title="Rpc" rel="Chapter" href="Rpc.html">
<link title="Rpc_program" rel="Chapter" href="Rpc_program.html">
<link title="Rpc_util" rel="Chapter" href="Rpc_util.html">
<link title="Rpc_portmapper_aux" rel="Chapter" href="Rpc_portmapper_aux.html">
<link title="Rpc_packer" rel="Chapter" href="Rpc_packer.html">
<link title="Rpc_transport" rel="Chapter" href="Rpc_transport.html">
<link title="Rpc_client" rel="Chapter" href="Rpc_client.html">
<link title="Rpc_simple_client" rel="Chapter" href="Rpc_simple_client.html">
<link title="Rpc_portmapper_clnt" rel="Chapter" href="Rpc_portmapper_clnt.html">
<link title="Rpc_portmapper" rel="Chapter" href="Rpc_portmapper.html">
<link title="Rpc_server" rel="Chapter" href="Rpc_server.html">
<link title="Rpc_auth_sys" rel="Chapter" href="Rpc_auth_sys.html">
<link title="Rpc_auth_gssapi" rel="Chapter" href="Rpc_auth_gssapi.html">
<link title="Rpc_proxy" rel="Chapter" href="Rpc_proxy.html">
<link title="Rpc_intro" rel="Chapter" href="Rpc_intro.html">
<link title="Rpc_mapping_ref" rel="Chapter" href="Rpc_mapping_ref.html">
<link title="Rpc_intro_gss" rel="Chapter" href="Rpc_intro_gss.html">
<link title="Shell_sys" rel="Chapter" href="Shell_sys.html">
<link title="Shell" rel="Chapter" href="Shell.html">
<link title="Shell_uq" rel="Chapter" href="Shell_uq.html">
<link title="Shell_fs" rel="Chapter" href="Shell_fs.html">
<link title="Shell_intro" rel="Chapter" href="Shell_intro.html">
<link title="Intro" rel="Chapter" href="Intro.html">
<link title="Platform" rel="Chapter" href="Platform.html">
<link title="Foreword" rel="Chapter" href="Foreword.html">
<link title="Ipv6" rel="Chapter" href="Ipv6.html">
<link title="Regexp" rel="Chapter" href="Regexp.html">
<link title="Tls" rel="Chapter" href="Tls.html">
<link title="Crypto" rel="Chapter" href="Crypto.html">
<link title="Authentication" rel="Chapter" href="Authentication.html">
<link title="Credentials" rel="Chapter" href="Credentials.html">
<link title="Gssapi" rel="Chapter" href="Gssapi.html">
<link title="Ocamlnet4" rel="Chapter" href="Ocamlnet4.html">
<link title="Get" rel="Chapter" href="Get.html"><link title="Classical API" rel="Section" href="#2_ClassicalAPI">
<link title="API with versioned access" rel="Section" href="#2_APIwithversionedaccess">
<link title="Classical functor" rel="Section" href="#2_Classicalfunctor">
<link title="Functor with versioned access" rel="Section" href="#2_Functorwithversionedaccess">
<link title="Netsys_global" rel="Section" href="#2_Netsysglobal">
<link title="Examples" rel="Section" href="#2_Examples">
<title>Ocamlnet 4 Reference Manual : Netplex_sharedvar</title>
</head>
<body>
<div class="navbar"><a class="pre" href="Netplex_semaphore.html" title="Netplex_semaphore">Previous</a>
<a class="up" href="index.html" title="Index">Up</a>
<a class="post" href="Netplex_mutex.html" title="Netplex_mutex">Next</a>
</div>
<h1>Module <a href="type_Netplex_sharedvar.html">Netplex_sharedvar</a></h1>
<pre><span id="MODULENetplex_sharedvar"><span class="keyword">module</span> Netplex_sharedvar</span>: <code class="code">sig</code> <a href="Netplex_sharedvar.html">..</a> <code class="code">end</code></pre><div class="info module top">
<div class="info-desc">
<p>Netplex-wide variables</p>
</div>
</div>
<hr width="100%">
<p>This plugin allows to have Netplex-global variables that can be read
and written by all components. These variables are useful to communicate
names and other small pieces of information across the whole Netplex.
For instance, one component could allocate a shared memory object, and
put its name into a variable to make it known to other components.</p>
<p>This implementation works in both multi-processing and
multi-threading netplex environments. It is, however, not very
fast, because the variables live in the controller, and the
access operations are realized by RPC's. It is good
enough when these operations are only infrequently called, e.g. in
the post-start and pre-finish processor callbacks.</p>
<p>Furthermore, note that it is unwise to put large values into
variables when using them in multi-processing contexts. The controller
process is also the parent process of all <code class="code">fork</code>ed children, and
when a lot of memory is allocated in the controller, all
this memory needs to be copied when the <code class="code">fork</code> is done. As workaround,
put such values into temporary files, and only pass the names of the
files around via variables.</p>
<p>Variables come in two flavors:</p>
<ul>
<li>String variables</li>
<li>Encapsulated variables (see <a href="Netplex_encap.html"><code class="code">Netplex_encap</code></a>)</li>
</ul>
<p>A string variable cannot be accessed as encapsulated variable, and
vice versa.</p>
<p>The latter kind is useful to safely store structured ocaml values in
Netplex variables.</p>
<p>More documentation can also be found here:
<code class="code">Netplex_advanced.sharedvars</code></p>
<p><b>Thread safety:</b> Full. The functions can be called from any thread.</p>
<pre><span id="EXCEPTIONSharedvar_type_mismatch"><span class="keyword">exception</span> Sharedvar_type_mismatch</span> <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info ">
<div class="info-desc">
<p>The (dynamically typed) variable has the wrong type (string/exn)</p>
</div>
</div>
<pre><span id="EXCEPTIONSharedvar_no_permission"><span class="keyword">exception</span> Sharedvar_no_permission</span> <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info ">
<div class="info-desc">
<p>It is not allowed to set the value</p>
</div>
</div>
<pre><span id="EXCEPTIONSharedvar_not_found"><span class="keyword">exception</span> Sharedvar_not_found</span> <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info ">
<div class="info-desc">
<p>The variable does not exist. Only used by <code class="code">Make_var_type</code></p>
</div>
</div>
<pre><span id="EXCEPTIONSharedvar_null"><span class="keyword">exception</span> Sharedvar_null</span></pre>
<div class="info ">
<div class="info-desc">
<p>The initial value of a shared exception variable</p>
</div>
</div>
<pre><span id="VALplugin"><span class="keyword">val</span> plugin</span> : <code class="type"><a href="Netplex_types.plugin-c.html">Netplex_types.plugin</a></code></pre><div class="info ">
<div class="info-desc">
<p>To enable shared variables, call the controller's <code class="code">add_plugin</code> method
with this object as argument. This can e.g. be done in the
<code class="code">post_add_hook</code> of the processor.</p>
</div>
</div>
<h3 id="2_ClassicalAPI">Classical API</h3><p>Most of the folloing functions can be invoked in both container
and controller contexts, with the notable exception of
<code class="code">wait_for_value</code>.</p>
<pre><span id="VALcreate_var"><span class="keyword">val</span> create_var</span> : <code class="type">?own:bool -><br> ?ro:bool -> ?enc:bool -> ?timeout:float -> ?ssn:string -> string -> bool</code></pre><div class="info ">
<div class="info-desc">
<p>Create the variable with the passed name with an empty string
(or the exception <code class="code">Sharedvar_null</code>) as
initial value. If the creation is possible (i.e. the variable did
not exist already), the function returns <code class="code">true</code>, otherwise
the already existing variable is left unchanged, and <code class="code">false</code> is
passed back. By default, the variable can be modified and deleted
by any other container. Two options allow you to change that:</p>
<ul>
<li><code class="code">own</code>: If true, the created variable is owned by the calling
socket service. Only the caller can delete it, and when the
last component of the socket service terminates, the variable is
automatically deleted. The deletion happens after the
<code class="code">post_finish_hook</code> is executed, so the variable is still accessible
from this hook. Note that the controller has unlimited access anyway.</li>
<li><code class="code">ro</code>: if true, only the owner can set the value</li>
<li><code class="code">enc</code>: if true, the variable stores encapsulated values, otherwise
strings
(defaults to false)</li>
<li><code class="code">timeout</code>: if passed, the variable will be automatically deleted
after this number of seconds. The timeout starts anew with every
read or write of the variable.</li>
<li><code class="code">ssn</code>: If called from the controller and <code class="code">own</code>, this must be set to the
socket service name of the owner</li>
</ul>
<p>Variable names are global to the whole netplex system. By convention,
these names are formed like <code class="code">"service_name.local_name"</code>, i.e. they
are prefixed by the socket service to which they refer.</p>
</div>
</div>
<pre><span id="VALdelete_var"><span class="keyword">val</span> delete_var</span> : <code class="type">string -> bool</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">delete_var name</code>: Deletes the variable <code class="code">name</code>. Returns <code class="code">true</code> if
the deletion could be carried out, and <code class="code">false</code> when the variable
does not exist, or the container does not have permission to delete
the variable.</p>
</div>
</div>
<pre><span id="VALset_value"><span class="keyword">val</span> set_value</span> : <code class="type">string -> string -> bool</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">set_value name value</code>: Sets the variable <code class="code">name</code> to <code class="code">value</code>. This
is only possible when the variable exists, and is writable.
Returns <code class="code">true</code> if the function is successful, and <code class="code">false</code> when
the variable does not exist.</p>
<p>Raises <code class="code">Sharedvar_no_permission</code> if the variable cannot be modified.</p>
<p>Raises <code class="code">Sharedvar_type_mismatch</code> if the variable is not a string
variable.</p>
</div>
</div>
<pre><span id="VALset_enc_value"><span class="keyword">val</span> set_enc_value</span> : <code class="type">string -> <a href="Netplex_types.html#TYPEencap">Netplex_types.encap</a> -> bool</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">set_enc_value name value</code>: Sets the variable <code class="code">name</code> to <code class="code">value</code>.
Return value as for <code class="code">set_value</code>.</p>
<p>Raises <code class="code">Sharedvar_no_permission</code> if the variable cannot be modified.</p>
<p>Raises <code class="code">Sharedvar_type_mismatch</code> if the variable is not encapsulated</p>
</div>
</div>
<pre><span id="VALget_value"><span class="keyword">val</span> get_value</span> : <code class="type">string -> string option</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">get_value name</code>: Gets the value of the variable <code class="code">name</code>. If the
variable does not exist, <code class="code">None</code> is returned.</p>
<p>Raises <code class="code">Sharedvar_type_mismatch</code> if the variable is not a string
variable.</p>
</div>
</div>
<pre><span id="VALget_enc_value"><span class="keyword">val</span> get_enc_value</span> : <code class="type">string -> <a href="Netplex_types.html#TYPEencap">Netplex_types.encap</a> option</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">get_enc_value name</code>: Gets the value of the variable <code class="code">name</code>. If the
variable does not exist, <code class="code">None</code> is returned.</p>
<p>Raises <code class="code">Sharedvar_type_mismatch</code> if the variable is not encapsulated</p>
</div>
</div>
<pre><span id="VALwait_for_value"><span class="keyword">val</span> wait_for_value</span> : <code class="type">string -> string option</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">wait_for_value name</code>: If the variable exists and <code class="code">set_value</code> has
already been called at least once, the current value is returned.
If the variable exists, but <code class="code">set_value</code> has not yet been called at all,
the function waits until <code class="code">set_value</code> is called, and returns the value
set then. If the variable does not exist, the function immediately
returns <code class="code">None</code>.</p>
<p>An ongoing wait is interrupted when the variable is deleted. In this
case <code class="code">None</code> is returned.</p>
<p><b>This function can only be invoked from container context!</b></p>
</div>
</div>
<pre><span id="VALwait_for_enc_value"><span class="keyword">val</span> wait_for_enc_value</span> : <code class="type">string -> <a href="Netplex_types.html#TYPEencap">Netplex_types.encap</a> option</code></pre><div class="info ">
<div class="info-desc">
<p>Same for encapsulated variables</p>
</div>
</div>
<pre><span id="VALget_lazily"><span class="keyword">val</span> get_lazily</span> : <code class="type">string -> (unit -> string) -> string option</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">get_lazily name f</code>: Uses the variable <code class="code">name</code> to ensure that <code class="code">f</code>
is only invoked when <code class="code">get_lazily</code> is called for the first time,
and that the value stored in the variable is returned the
next times. This works from whatever component <code class="code">get_lazily</code>
is called.</p>
<p>If <code class="code">f()</code> raises an exception, the exception is suppressed, and
<code class="code">None</code> is returned as result of <code class="code">get_lazily</code>. Exceptions are not
stored in the variable, so the next time <code class="code">get_lazily</code> is called
it is again tried to compute the value of <code class="code">f()</code>. If you want to
catch the exception this must done in the body of <code class="code">f</code>.</p>
<p>No provisions are taken to delete the variable. If <code class="code">delete_var</code>
is called by user code (which is allowed at any time), and
<code class="code">get_lazily</code> is called again, the lazy value will again be computed.</p>
<p><b>This function can only be invoked from container context!</b></p>
</div>
</div>
<pre><span id="VALget_enc_lazily"><span class="keyword">val</span> get_enc_lazily</span> : <code class="type">string -> (unit -> <a href="Netplex_types.html#TYPEencap">Netplex_types.encap</a>) -> <a href="Netplex_types.html#TYPEencap">Netplex_types.encap</a> option</code></pre><div class="info ">
<div class="info-desc">
<p>Same for encapsulated values</p>
</div>
</div>
<pre><span id="VALdump"><span class="keyword">val</span> dump</span> : <code class="type">string -> <a href="Netlog.html#TYPElevel">Netlog.level</a> -> unit</code></pre><div class="info ">
<div class="info-desc">
<p>Dumps the access counter of this variable to <a href="Netlog.html"><code class="code">Netlog</code></a>. The
string argument "*" dumps all variables.</p>
</div>
</div>
<h3 id="2_APIwithversionedaccess">API with versioned access</h3><p>The API with versioned values can very quickly check whether newer
values are available (the check consists just of a memory read). If a newer
version is avaiable, the value still needs to be retrieved with an
RPC call, though.</p>
<p>The central function is <code class="code">vv_update</code>. See also the limitations mentioned
there.</p>
<pre><span id="TYPEversioned_value"><span class="keyword">type</span> <code class="type">'a</code> versioned_value</span> </pre>
<div class="info ">
<div class="info-desc">
<p>Cache for the current value</p>
</div>
</div>
<pre><span id="VALvv_access"><span class="keyword">val</span> vv_access</span> : <code class="type">string -> string <a href="Netplex_sharedvar.html#TYPEversioned_value">versioned_value</a></code></pre><div class="info ">
<div class="info-desc">
<p>Get the current value of this variable. This succeeds even when the
variable does not exist.</p>
</div>
</div>
<pre><span id="VALvv_access_enc"><span class="keyword">val</span> vv_access_enc</span> : <code class="type">string -> <a href="Netplex_types.html#TYPEencap">Netplex_types.encap</a> <a href="Netplex_sharedvar.html#TYPEversioned_value">versioned_value</a></code></pre><div class="info ">
<div class="info-desc">
<p>Same for encapsulated variables</p>
</div>
</div>
<pre><span id="VALvv_get"><span class="keyword">val</span> vv_get</span> : <code class="type">'a <a href="Netplex_sharedvar.html#TYPEversioned_value">versioned_value</a> -> 'a option</code></pre><div class="info ">
<div class="info-desc">
<p>Extract the current value, or <code class="code">None</code> if the variable cannot be found.</p>
</div>
</div>
<pre><span id="VALvv_version"><span class="keyword">val</span> vv_version</span> : <code class="type">'a <a href="Netplex_sharedvar.html#TYPEversioned_value">versioned_value</a> -> int64</code></pre><div class="info ">
<div class="info-desc">
<p>Get the current version number. The version number is increased by
every "set" operation. Raised <code class="code">Not_found</code> if the variable cannot be
found.</p>
</div>
</div>
<pre><span id="VALvv_update"><span class="keyword">val</span> vv_update</span> : <code class="type">'a <a href="Netplex_sharedvar.html#TYPEversioned_value">versioned_value</a> -> bool</code></pre><div class="info ">
<div class="info-desc">
<p>Check whether there is a new version of the value, and update the
cache. Return whether the update occurred.</p>
<p>Note that there is a limitation on the number of variables that can
use <code class="code">vv_update</code>. For every <code class="code">versioned_value</code> a slot in a shared memory
segment is allocated. However, there is only a limited number of such
slots (currently 1023). If more slots are needed, the performance will
be degraded.</p>
</div>
</div>
<pre><span id="VALvv_set"><span class="keyword">val</span> vv_set</span> : <code class="type">'a <a href="Netplex_sharedvar.html#TYPEversioned_value">versioned_value</a> -> 'a -> bool</code></pre><div class="info ">
<div class="info-desc">
<p>Set the current value. Return whether successful</p>
</div>
</div>
<h3 id="2_Classicalfunctor">Classical functor</h3>
<pre><span id="MODULEMake_var_type"><span class="keyword">module</span> <a href="Netplex_sharedvar.Make_var_type.html">Make_var_type</a></span>: <div class="sig_block"><code class="code">functor (</code><code class="code">T</code><code class="code"> : </code><code class="type"><a href="Netplex_cenv.TYPE.html">Netplex_cenv.TYPE</a></code><code class="code">) -> </code><code class="type"><a href="Netplex_cenv.VAR_TYPE.html">Netplex_cenv.VAR_TYPE</a></code><code class="type"> with type t = T.t</code></div></pre><div class="info">
<p>Creates a module with <code class="code">get</code> and <code class="code">set</code> functions to access variables
of type <code class="code">T.t</code>.</p>
</div>
<h3 id="2_Functorwithversionedaccess">Functor with versioned access</h3>
<pre><span id="MODULETYPEVV_TYPE"><span class="keyword">module type</span> <a href="Netplex_sharedvar.VV_TYPE.html">VV_TYPE</a></span> = <code class="code">sig</code> <a href="Netplex_sharedvar.VV_TYPE.html">..</a> <code class="code">end</code></pre>
<pre><span id="MODULEMake_vv"><span class="keyword">module</span> <a href="Netplex_sharedvar.Make_vv.html">Make_vv</a></span>: <div class="sig_block"><code class="code">functor (</code><code class="code">T</code><code class="code"> : </code><code class="type"><a href="Netplex_cenv.TYPE.html">Netplex_cenv.TYPE</a></code><code class="code">) -> </code><code class="type"><a href="Netplex_sharedvar.VV_TYPE.html">VV_TYPE</a></code><code class="type"> with type t = T.t</code></div></pre><h3 id="2_Netsysglobal">Netsys_global</h3><p>This is a propagator for <a href="Netsys_global.html"><code class="code">Netsys_global</code></a>. It is automatically activated
when the Netplex controller is started.</p>
<pre><span id="VALglobal_propagator"><span class="keyword">val</span> global_propagator</span> : <code class="type">unit -> <a href="Netsys_global.propagator-c.html">Netsys_global.propagator</a></code></pre><div class="info ">
<div class="info-desc">
<p>Create a new propagator, and initialize <a href="Netplex_sharedvar.html"><code class="code">Netplex_sharedvar</code></a>
with the current variables from <a href="Netsys_global.html"><code class="code">Netsys_global</code></a>. Note that a
global variable with name <code class="code">n</code> appears in Netplex as variable
<code class="code">"global." ^ n</code>.</p>
<p>The version numbers appearing in both modules are unrelated.</p>
<p>This function must be called from controller context.</p>
</div>
</div>
<pre><span id="VALpropagate_back"><span class="keyword">val</span> propagate_back</span> : <code class="type"><a href="Netplex_types.controller-c.html">Netplex_types.controller</a> -> unit</code></pre><div class="info ">
<div class="info-desc">
<p>Copy the global variables from <a href="Netplex_sharedvar.html"><code class="code">Netplex_sharedvar</code></a> (with prefix
"global.") back to <a href="Netsys_global.html"><code class="code">Netsys_global</code></a></p>
</div>
</div>
<h3 id="2_Examples">Examples</h3><p>Example code:</p>
<p>Here, one randomly chosen container computes <code class="code">precious_value</code>, and
makes it available to all others, so the other container can simply
grab the value. This is similar to what <code class="code">get_lazily</code> does internally:</p>
<pre class="codepre"><code class="code"> let get_precious_value() =
let container = Netplex_cenv.self_cont() in
let var_name = "my_service.precious" in
if Netplex_sharedvar.create_var var_name then (
let precious_value =
try ... (* some costly computation *)
with exn ->
ignore(Netplex_sharedvar.delete_var var_name);
raise exn in
let b = Netplex_sharedvar.set_value var_name precious_value in
assert b;
precious_value
)
else (
match Netplex_sharedvar.wait_for_value var_name with
| Some v -> v
| None -> failwith "get_precious_value"
(* or do plan B, e.g. compute the value *)
)
</code></pre>
<p>We don't do anything here for deleting the value when it is no longer
needed. Finding a criterion for that is very application-specific.
If the variable can be thought as being another service endpoint
of a socket service, it is a good idea to acquire the ownership
(by passing <code class="code">~own:true</code> to <code class="code">create_var</code>), so the variable is automatically
deleted when the socket service stops.</p>
<p>Of course, the plugin must be enabled, e.g. by overriding the
<code class="code">post_add_hook</code> processor hook:</p>
<pre class="codepre"><code class="code">
method post_add_hook sockserv ctrl =
ctrl # add_plugin Netplex_sharedvar.plugin
</code></pre></body></html>
|
