-
Notifications
You must be signed in to change notification settings - Fork 145
/
protocols.js
1264 lines (1126 loc) · 34.4 KB
/
protocols.js
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
/* jshint node: true */
// TODO: Optimize MessageEncoder by avoiding the extra copy on transform.
// TODO: Add timeout as emitter options?
// TODO: Add error hook to allow transformation of system errors?
// TODO: Add protocol `discover` method?
// TODO: Add clear protocol cache method?
// TODO: Return something useful when emitting a message (e.g. number of
// pending messages).
'use strict';
/**
* This module implements Avro's IPC/RPC logic.
*
* This is done the Node.js way, mimicking the `EventEmitter` class.
*
*/
var types = require('./types'),
utils = require('./utils'),
events = require('events'),
stream = require('stream'),
util = require('util');
var BOOLEAN_TYPE = types.createType('boolean');
var STRING_TYPE = types.createType('string');
var SYSTEM_ERROR_TYPE = types.createType(['string']);
var HANDSHAKE_REQUEST_TYPE = types.createType({
namespace: 'org.apache.avro.ipc',
name: 'HandshakeRequest',
type: 'record',
fields: [
{name: 'clientHash', type: {name: 'MD5', type: 'fixed', size: 16}},
{name: 'clientProtocol', type: ['null', 'string'], 'default': null},
{name: 'serverHash', type: 'org.apache.avro.ipc.MD5'},
{
name: 'meta',
type: ['null', {type: 'map', values: 'bytes'}],
'default': null
}
]
});
var HANDSHAKE_RESPONSE_TYPE = types.createType({
namespace: 'org.apache.avro.ipc',
name: 'HandshakeResponse',
type: 'record',
fields: [
{
name: 'match',
type: {
name: 'HandshakeMatch',
type: 'enum',
symbols: ['BOTH', 'CLIENT', 'NONE']
}
},
{name: 'serverProtocol', type: ['null', 'string'], 'default': null},
{
name: 'serverHash',
type: ['null', {name: 'MD5', type: 'fixed', size: 16}],
'default': null
},
{
name: 'meta',
type: ['null', {type: 'map', values: 'bytes'}],
'default': null
}
]
});
var HandshakeRequest = HANDSHAKE_REQUEST_TYPE.getRecordConstructor();
var HandshakeResponse = HANDSHAKE_RESPONSE_TYPE.getRecordConstructor();
var Tap = utils.Tap;
var f = util.format;
/**
* Protocol generation function.
*
* This should be used instead of the protocol constructor. The protocol's
* constructor performs no logic to better support efficient protocol copy.
*
*/
function createProtocol(attrs, opts) {
opts = opts || {};
var name = attrs.protocol;
if (!name) {
throw new Error('missing protocol name');
}
opts.namespace = attrs.namespace;
if (opts.namespace && !~name.indexOf('.')) {
name = f('%s.%s', opts.namespace, name);
}
if (attrs.types) {
attrs.types.forEach(function (obj) { types.createType(obj, opts); });
}
var messages = {};
if (attrs.messages) {
Object.keys(attrs.messages).forEach(function (key) {
messages[key] = new Message(key, attrs.messages[key], opts);
});
}
return new Protocol(name, messages, opts.registry || {});
}
/**
* An Avro protocol.
*
* It contains a cache for all remote protocols encountered by its emitters and
* listeners. Note that a protocol can be listening to multiple listeners at a
* given time. This can be a mix of stateful or stateless listeners.
*
*/
function Protocol(name, messages, types, ptcl) {
this._name = name;
this._messages = messages;
this._types = types;
this._parent = ptcl;
// Cache a string instead of the buffer to avoid retaining an entire slab.
this._hashString = utils.getFingerprint(this.toString()).toString('binary');
// Listener callbacks. Note the prototype used for handlers when this is a
// subprotocol. This lets us easily implement the desired fallback behavior.
var self = this;
this._handlers = Object.create(ptcl ? ptcl._handlers : null);
this._onListenerCall = function (name, req, cb) {
var handler = self._handlers[name];
if (handler) {
handler.call(self, req, this, cb);
} else if (cb) {
// This (listening) protocol hasn't implemented this message.
cb(new Error(f('unhandled message: %s', name)));
}
};
// Resolvers are split since we want emitters to still be able to talk to
// servers with more messages (which would be incompatible the other way).
this._emitterResolvers = ptcl ? ptcl._emitterResolvers : {};
this._listenerResolvers = ptcl ? ptcl._listenerResolvers : {};
}
Protocol.prototype.subprotocol = function () {
return new Protocol(this._name, this._messages, this._types, this);
};
Protocol.prototype.emit = function (name, req, emitter, cb) {
cb = cb || function (err) { emitter.emit('error', err); };
if (
!(emitter instanceof MessageEmitter) ||
emitter._ptcl._hashString !== this._hashString
) {
asyncAvroCb(this, cb, 'invalid emitter');
return;
}
var message = this._messages[name];
if (!message) {
asyncAvroCb(this, cb, f('unknown message: %s', name));
return;
}
emitter._emit(message, req, cb);
};
Protocol.prototype.createEmitter = function (transport, opts, cb) {
if (!cb && typeof opts == 'function') {
cb = opts;
opts = undefined;
}
var emitter;
if (typeof transport == 'function') {
emitter = new StatelessEmitter(this, transport, opts);
} else {
var readable, writable;
if (isStream(transport)) {
readable = writable = transport;
} else {
readable = transport.readable;
writable = transport.writable;
}
emitter = new StatefulEmitter(this, readable, writable, opts);
}
if (cb) {
emitter.once('eot', cb);
}
return emitter;
};
Protocol.prototype.on = function (name, handler) {
if (!this._messages[name]) {
throw new Error(f('unknown message: %s', name));
}
this._handlers[name] = handler;
return this;
};
Protocol.prototype.createListener = function (transport, opts, cb) {
if (!cb && typeof opts == 'function') {
cb = opts;
opts = undefined;
}
var listener;
if (typeof transport == 'function') {
listener = new StatelessListener(this, transport, opts);
} else {
var readable, writable;
if (isStream(transport)) {
readable = writable = transport;
} else {
readable = transport.readable;
writable = transport.writable;
}
listener = new StatefulListener(this, readable, writable, opts);
}
if (cb) {
listener.once('eot', cb);
}
return listener.on('_call', this._onListenerCall);
};
Protocol.prototype.getType = function (name) { return this._types[name]; };
Protocol.prototype.getName = function () { return this._name; };
Protocol.prototype.getMessages = function () { return this._messages; };
Protocol.prototype.toString = function () {
var namedTypes = [];
Object.keys(this._types).forEach(function (name) {
var type = this._types[name];
if (type.getName()) {
namedTypes.push(type);
}
}, this);
return types.stringify({
protocol: this._name,
types: namedTypes.length ? namedTypes : undefined,
messages: this._messages
});
};
Protocol.prototype.inspect = function () {
return f('<Protocol %j>', this._name);
};
/**
* Base message emitter class.
*
* See below for the two available variants.
*
*/
function MessageEmitter(ptcl, opts) {
events.EventEmitter.call(this);
this._ptcl = ptcl;
this._resolvers = ptcl._emitterResolvers;
this._serverHashString = ptcl._hashString;
this._idType = IdType.createMetadataType(opts.IdType);
this._bufferSize = opts.bufferSize || 2048;
this._frameSize = opts.frameSize || 2048;
this.once('_eot', function (pending) { this.emit('eot', pending); });
}
util.inherits(MessageEmitter, events.EventEmitter);
MessageEmitter.prototype._generateResolvers = function (
hashString, serverPtcl
) {
var resolvers = {};
var emitterMessages = this._ptcl._messages;
var serverMessages = serverPtcl._messages;
Object.keys(emitterMessages).forEach(function (name) {
var cm = emitterMessages[name];
var sm = serverMessages[name];
if (!sm) {
throw new Error(f('missing server message: %s', name));
}
if (cm.oneWay !== sm.oneWay) {
throw new Error(f('incompatible one-way options for message: %s', name));
}
resolvers[name] = {
responseType: cm.responseType.createResolver(sm.responseType),
errorType: cm.errorType.createResolver(sm.errorType)
};
});
this._resolvers[hashString] = resolvers;
};
MessageEmitter.prototype._createHandshakeRequest = function (
hashString, noPtcl
) {
return new HandshakeRequest(
getHash(this._ptcl),
noPtcl ? null : {string: this._ptcl.toString()},
new Buffer(hashString, 'binary')
);
};
MessageEmitter.prototype._finalizeHandshake = function (tap, handshakeReq) {
var res = HANDSHAKE_RESPONSE_TYPE._read(tap);
this.emit('handshake', handshakeReq, res);
if (handshakeReq.clientProtocol && res.match === 'NONE') {
// If the emitter's protocol was included in the original request, this is
// not a failure which a retry will fix.
var buf = res.meta && res.meta.map.error;
throw new Error(buf ? buf.toString() : 'handshake error');
}
var hashString;
if (res.serverHash && res.serverProtocol) {
// This means the request didn't include the correct server hash. Note that
// we use the handshake response's hash rather than our computed one in
// case the server computes it differently.
hashString = res.serverHash['org.apache.avro.ipc.MD5'].toString('binary');
if (!canResolve(this, hashString)) {
this._generateResolvers(
hashString,
createProtocol(JSON.parse(res.serverProtocol.string))
);
}
// Make this hash the new default.
this._serverHashString = hashString;
} else {
hashString = handshakeReq.serverHash.toString('binary');
}
// We return the server's hash for stateless emitters. It might be that the
// default hash changes in between requests, in which case using the default
// one will fail.
return {match: res.match, serverHashString: hashString};
};
MessageEmitter.prototype._encodeRequest = function (tap, message, req) {
safeWrite(tap, STRING_TYPE, message.name);
safeWrite(tap, message.requestType, req);
};
MessageEmitter.prototype._decodeArguments = function (
tap, hashString, message
) {
var resolvers = getResolvers(this, hashString, message);
var args = [null, null];
if (tap.readBoolean()) {
args[0] = resolvers.errorType._read(tap);
} else {
args[1] = resolvers.responseType._read(tap);
}
if (!tap.isValid()) {
throw new Error('truncated message');
}
return args;
};
/**
* Factory-based emitter.
*
* This emitter doesn't keep a persistent connection to the server and requires
* prepending a handshake to each message emitted. Usage examples include
* talking to an HTTP server (where the factory returns an HTTP request).
*
* Since each message will use its own writable/readable stream pair, the
* advantage of this emitter is that it is able to keep track of which response
* corresponds to each request without relying on messages' metadata. In
* particular, this means these emitters are compatible with any server
* implementation.
*
*/
function StatelessEmitter(ptcl, writableFactory, opts) {
opts = opts || {};
MessageEmitter.call(this, ptcl, opts);
this._writableFactory = writableFactory;
this._id = 1;
this._pending = {};
this._destroyed = false;
this._interrupted = false;
}
util.inherits(StatelessEmitter, MessageEmitter);
StatelessEmitter.prototype._emit = function (message, req, cb) {
// We enclose the server's hash inside this message's closure since the
// emitter might be emitting several message concurrently and the hash might
// change before the response returns (unlikely but possible if the emitter
// talks to multiple servers at once or the server changes protocol).
var serverHashString = this._serverHashString;
var id = this._id++;
var self = this;
this._pending[id] = cb;
if (this._destroyed) {
asyncAvroCb(undefined, done, 'emitter destroyed');
return;
}
emit(false);
function emit(retry) {
var tap = new Tap(new Buffer(self._bufferSize));
var handshakeReq = self._createHandshakeRequest(serverHashString, !retry);
safeWrite(tap, HANDSHAKE_REQUEST_TYPE, handshakeReq);
try {
safeWrite(tap, self._idType, id);
self._encodeRequest(tap, message, req);
} catch (err) {
asyncAvroCb(undefined, done, err);
return;
}
var writable = self._writableFactory(function onReadable(readable) {
if (self._interrupted) {
// In case this function is called asynchronously (e.g. when sending
// HTTP requests), it might be that we have ended since.
return;
}
readable
.pipe(new MessageDecoder(!message.oneWay))
.on('error', done)
// This will happen when the message isn't one way and the readable
// stream ends before a single message has been decoded (e.g. on
// invalid response).
.on('data', function (buf) {
readable.unpipe(this); // Single message per readable stream.
if (self._interrupted) {
return;
}
var tap = new Tap(buf);
try {
var info = self._finalizeHandshake(tap, handshakeReq);
serverHashString = info.serverHashString;
if (info.match === 'NONE') {
emit(true); // Retry, attaching emitter protocol this time.
return;
}
self._idType._read(tap); // Skip metadata.
var args = self._decodeArguments(tap, serverHashString, message);
} catch (err) {
done(err);
return;
}
if (!message.oneWay) {
done.apply(undefined, args);
}
});
});
var encoder = new MessageEncoder(self._frameSize);
encoder.pipe(writable);
encoder.end(tap.getValue());
}
function done(err, res) {
var cb = self._pending[id];
delete self._pending[id];
cb.call(self._ptcl, err, res);
if (self._destroyed) {
self.destroy();
}
}
};
StatelessEmitter.prototype.destroy = function (noWait) {
this._destroyed = true;
var pendingIds = Object.keys(this._pending);
if (noWait) {
this._interrupted = true;
pendingIds.forEach(function (id) {
this._pending[id]({string: 'interrupted'});
delete this._pending[id];
}, this);
}
if (noWait || !pendingIds.length) {
this.emit('_eot', pendingIds.length);
}
};
/**
* Multiplexing emitter.
*
* These emitters reuse the same streams (both readable and writable) for all
* messages. This avoids a lot of overhead (e.g. creating new connections,
* re-issuing handshakes) but requires the server to include compatible
* metadata in each response (namely forwarding each request's ID into its
* response).
*
* A custom metadata format can be specified via the `idType` option. The
* default is compatible with this package's default server (i.e. listener)
* implementation.
*
*/
function StatefulEmitter(ptcl, readable, writable, opts) {
opts = opts || {};
MessageEmitter.call(this, ptcl, opts);
this._readable = readable;
this._writable = writable;
this._id = 1;
this._pending = {};
this._started = false;
this._destroyed = false;
this._ended = false; // Readable input ended.
this._decoder = new MessageDecoder();
this._encoder = new MessageEncoder(this._frameSize);
var handshakeReq = null;
var self = this;
process.nextTick(function () {
self._readable.pipe(self._decoder)
.on('error', function (err) { self.emit('error', err); })
.on('data', onHandshakeData)
.on('end', function () {
self._ended = true;
self.destroy();
});
self._encoder.pipe(self._writable);
emitHandshake(true);
});
function emitHandshake(noPtcl) {
handshakeReq = self._createHandshakeRequest(
self._serverHashString,
noPtcl
);
self._encoder.write(handshakeReq.toBuffer());
}
function onHandshakeData(buf) {
var tap = new Tap(buf);
try {
var info = self._finalizeHandshake(tap, handshakeReq);
} catch (err) {
self.emit('error', err);
self.destroy(); // This isn't a recoverable error.
return;
}
if (info.match !== 'NONE') {
self._decoder
.removeListener('data', onHandshakeData)
.on('data', onMessageData);
self._started = true;
self.emit('_start'); // Send any pending messages.
} else {
emitHandshake(false);
}
}
function onMessageData(buf) {
var tap = new Tap(buf);
try {
var id = self._idType._read(tap);
if (!id) {
throw new Error('missing ID');
}
} catch (err) {
self.emit('error', new Error('invalid metadata: ' + err.message));
return;
}
var info = self._pending[id];
if (info === undefined) {
self.emit('error', new Error('orphan response: ' + id));
return;
}
try {
var args = self._decodeArguments(
tap,
self._serverHashString,
info.message
);
} catch (err) {
info.cb({string: 'invalid response: ' + err.message});
return;
}
delete self._pending[id];
info.cb.apply(self._ptcl, args);
if (self._destroyed) {
self.destroy();
}
}
}
util.inherits(StatefulEmitter, MessageEmitter);
StatefulEmitter.prototype._emit = function (message, req, cb) {
if (this._destroyed) {
asyncAvroCb(this._ptcl, cb, 'emitter destroyed');
return;
}
var self = this;
if (!this._started) {
this.once('_start', function () { self._emit(message, req, cb); });
return;
}
var tap = new Tap(new Buffer(this._bufferSize));
var id = this._id++;
try {
safeWrite(tap, this._idType, -id);
this._encodeRequest(tap, message, req);
} catch (err) {
asyncAvroCb(this._ptcl, cb, err);
return;
}
if (!message.oneWay) {
this._pending[id] = {message: message, cb: cb};
}
this._encoder.write(tap.getValue());
};
StatefulEmitter.prototype.destroy = function (noWait) {
this._destroyed = true;
if (!this._started) {
this.emit('_start'); // Error out any pending calls.
}
var pendingIds = Object.keys(this._pending);
if (pendingIds.length && !(noWait || this._ended)) {
return; // Wait for pending requests.
}
pendingIds.forEach(function (id) {
var cb = this._pending[id].cb;
delete this._pending[id];
cb({string: 'interrupted'});
}, this);
this._readable.unpipe(this._decoder);
this._encoder.unpipe(this._writable);
this.emit('_eot', pendingIds.length);
};
/**
* The server-side emitter equivalent.
*
* In particular it is responsible for handling handshakes appropriately.
*
*/
function MessageListener(ptcl, opts) {
events.EventEmitter.call(this);
opts = opts || {};
this._ptcl = ptcl;
this._resolvers = ptcl._listenerResolvers;
this._emitterHashString = null;
this._idType = IdType.createMetadataType(opts.IdType);
this._bufferSize = opts.bufferSize || 2048;
this._frameSize = opts.frameSize || 2048;
this._decoder = new MessageDecoder();
this._encoder = new MessageEncoder(this._frameSize);
this._destroyed = false;
this._pending = 0;
this.once('_eot', function (pending) { this.emit('eot', pending); });
}
util.inherits(MessageListener, events.EventEmitter);
MessageListener.prototype._generateResolvers = function (
hashString, emitterPtcl
) {
var resolvers = {};
var clientMessages = emitterPtcl._messages;
var serverMessages = this._ptcl._messages;
Object.keys(clientMessages).forEach(function (name) {
var sm = serverMessages[name];
if (!sm) {
throw new Error(f('missing server message: %s', name));
}
var cm = clientMessages[name];
if (cm.oneWay !== sm.oneWay) {
throw new Error(f('incompatible one-way options for message: %s', name));
}
resolvers[name] = {
requestType: sm.requestType.createResolver(cm.requestType)
};
});
this._resolvers[hashString] = resolvers;
};
MessageListener.prototype._validateHandshake = function (reqTap, resTap) {
// Reads handshake request and write corresponding response out. If an error
// occurs when parsing the request, a response with match NONE will be sent.
// Also emits 'handshake' event with both the request and the response.
var validationErr = null;
try {
var handshakeReq = HANDSHAKE_REQUEST_TYPE._read(reqTap);
var serverHashString = handshakeReq.serverHash.toString('binary');
} catch (err) {
validationErr = err;
}
if (!validationErr) {
this._emitterHashString = handshakeReq.clientHash.toString('binary');
if (!canResolve(this, this._emitterHashString)) {
var emitterPtclString = handshakeReq.clientProtocol;
if (emitterPtclString) {
try {
this._generateResolvers(
this._emitterHashString,
createProtocol(JSON.parse(emitterPtclString.string))
);
} catch (err) {
validationErr = err;
}
} else {
validationErr = new Error('unknown client protocol hash');
}
}
}
// We use the handshake response's meta field to transmit an eventual error
// to the client. This will let us display a more useful message later on.
var serverMatch = serverHashString === this._ptcl._hashString;
var handshakeRes = new HandshakeResponse(
validationErr ? 'NONE' : serverMatch ? 'BOTH' : 'CLIENT',
serverMatch ? null : {string: this._ptcl.toString()},
serverMatch ? null : {'org.apache.avro.ipc.MD5': getHash(this._ptcl)},
validationErr ? {map: {error: new Buffer(validationErr.message)}} : null
);
this.emit('handshake', handshakeReq, handshakeRes);
safeWrite(resTap, HANDSHAKE_RESPONSE_TYPE, handshakeRes);
return validationErr === null;
};
MessageListener.prototype._decodeRequest = function (tap, message) {
var resolvers = getResolvers(this, this._emitterHashString, message);
var val = resolvers.requestType._read(tap);
if (!tap.isValid()) {
throw new Error('invalid request');
}
return val;
};
MessageListener.prototype._encodeSystemError = function (tap, err) {
safeWrite(tap, BOOLEAN_TYPE, true);
safeWrite(tap, SYSTEM_ERROR_TYPE, avroError(err));
};
MessageListener.prototype._encodeArguments = function (
tap, message, err, res
) {
var noError = err === null;
var pos = tap.pos;
safeWrite(tap, BOOLEAN_TYPE, !noError);
try {
if (noError) {
safeWrite(tap, message.responseType, res);
} else {
if (err instanceof Error) {
// Convenience to allow emitter to use JS errors inside handlers.
err = avroError(err);
}
safeWrite(tap, message.errorType, err);
}
} catch (err) {
tap.pos = pos;
this._encodeSystemError(tap, err);
}
};
MessageListener.prototype.destroy = function (noWait) {
if (!this._destroyed) {
// Stop listening. This will also correctly push back any unused bytes into
// the readable stream (via `MessageDecoder`'s `unpipe` handler).
this._readable.unpipe(this._decoder);
}
this._destroyed = true;
if (noWait || !this._pending) {
this._encoder.unpipe(this._writable);
this.emit('_eot', this._pending);
}
};
/**
* Listener for stateless transport.
*
* This listener expect a handshake to precede each message.
*
*/
function StatelessListener(ptcl, readableFactory, opts) {
MessageListener.call(this, ptcl, opts);
this._tap = new Tap(new Buffer(this._bufferSize));
this._message = undefined;
var self = this;
this._readable = readableFactory(function (writable) {
// The encoder will buffer writes that happen before this function is
// called, so we don't need to do any special handling.
self._writable = self._encoder
.pipe(writable)
.on('finish', onEnd);
});
this._readable.pipe(this._decoder)
.on('data', onRequestData)
.on('end', onEnd);
function onRequestData(buf) {
self._pending++;
self.destroy(); // Only one message per stateless listener.
var reqTap = new Tap(buf);
if (!self._validateHandshake(reqTap, self._tap)) {
onResponse(new Error('invalid handshake'));
return;
}
try {
self._idType._read(reqTap); // Skip metadata.
var name = STRING_TYPE._read(reqTap);
self._message = self._ptcl._messages[name];
if (!self._message) {
throw new Error(f('unknown message: %s', name));
}
var req = self._decodeRequest(reqTap, self._message);
} catch (err) {
onResponse(err);
return;
}
if (self._message.oneWay) {
self.emit('_call', name, req);
onResponse(null, null);
} else {
self.emit('_call', name, req, onResponse);
}
}
function onResponse(err, res) {
safeWrite(self._tap, self._idType, 0);
if (!self._message) {
self._encodeSystemError(self._tap, err);
} else {
self._encodeArguments(self._tap, self._message, err, res);
}
self._pending--;
self._encoder.end(self._tap.getValue());
}
function onEnd() { self.destroy(); }
}
util.inherits(StatelessListener, MessageListener);
/**
* Stateful transport listener.
*
* A handshake is done when the listener is first opened, then all messages are
* sent without.
*
*/
function StatefulListener(ptcl, readable, writable, opts) {
MessageListener.call(this, ptcl, opts);
this._readable = readable;
this._writable = writable;
var self = this;
this._readable
.pipe(this._decoder)
.on('data', onHandshakeData)
.on('end', function () { self.destroy(); });
this._encoder
.pipe(this._writable)
.on('finish', function () { self.destroy(); });
function onHandshakeData(buf) {
var reqTap = new Tap(buf);
var resTap = new Tap(new Buffer(self._bufferSize));
if (self._validateHandshake(reqTap, resTap)) {
self._decoder
.removeListener('data', onHandshakeData)
.on('data', onRequestData);
}
self._encoder.write(resTap.getValue());
}
function onRequestData(buf) {
var reqTap = new Tap(buf);
var resTap = new Tap(new Buffer(self._bufferSize));
var id = 0;
try {
id = -self._idType._read(reqTap) | 0;
if (!id) {
throw new Error('missing ID');
}
} catch (err) {
self.emit('error', new Error('invalid metadata: ' + err.message));
return;
}
self._pending++;
try {
var name = STRING_TYPE._read(reqTap);
var message = self._ptcl._messages[name];
if (!message) {
throw new Error('unknown message: ' + name);
}
var req = self._decodeRequest(reqTap, message);
} catch (err) {
onResponse(err);
return;
}
if (message.oneWay) {
self.emit('_call', name, req);
self._pending--;
} else {
self.emit('_call', name, req, onResponse);
}
function onResponse(err, res) {
self._pending--;
safeWrite(resTap, self._idType, id);
if (!message) {
self._encodeSystemError(resTap, err);
} else {
self._encodeArguments(resTap, message, err, res);
}
self._encoder.write(resTap.getValue(), undefined, function () {
if (!self._pending && self._destroyed) {
self.destroy(); // For real this time.
}
});
}
}
}
util.inherits(StatefulListener, MessageListener);
// Helpers.
/**
* An Avro message.
*
*/
function Message(name, attrs, opts) {
this.name = name;
this.requestType = types.createType({
name: name,
type: 'request',
fields: attrs.request
}, opts);
if (!attrs.response) {
throw new Error('missing response');
}
this.responseType = types.createType(attrs.response, opts);
var errors = attrs.errors || [];
errors.unshift('string');
this.errorType = types.createType(errors, opts);
this.oneWay = !!attrs['one-way'];
if (this.oneWay) {
if (
!(this.responseType instanceof types.builtins.NullType) ||
errors.length > 1
) {
throw new Error('unapplicable one-way parameter');
}
}
}
Message.prototype.toJSON = function () {
var obj = {
request: this.requestType.getFields(),
response: this.responseType
};
var errorTypes = this.errorType.getTypes();
if (errorTypes.length > 1) {
obj.errors = types.createType(errorTypes.slice(1));
}
if (this.oneWay) {
obj['one-way'] = true;
}
return obj;
};