-
Notifications
You must be signed in to change notification settings - Fork 18
/
client.go
745 lines (663 loc) · 20.5 KB
/
client.go
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
package rpc
import (
"context"
"io"
"reflect"
"sync"
"github.com/libp2p/go-libp2p/core/host"
"github.com/libp2p/go-libp2p/core/peer"
"github.com/libp2p/go-libp2p/core/protocol"
stats "github.com/libp2p/go-libp2p-gorpc/stats"
)
// ClientOption allows for functional setting of options on a Client.
type ClientOption func(*Client)
// WithClientStatsHandler provides an implementation of stats.Handler to be
// used by the Client.
func WithClientStatsHandler(h stats.Handler) ClientOption {
return func(c *Client) {
c.statsHandler = h
}
}
// WithMultiStreamBufferSize sets the channel sizes for multiStream calls.
// Reading from the argument channel will proceed as long as none of the
// destinations have filled their buffer. See MultiStream().
func WithMultiStreamBufferSize(size int) ClientOption {
return func(c *Client) {
c.multiStreamBufferSize = size
}
}
// Client represents an RPC client which can perform calls to a remote
// (or local, see below) Server.
type Client struct {
host host.Host
protocol protocol.ID
server *Server
statsHandler stats.Handler
multiStreamBufferSize int
}
// NewClient returns a new Client which uses the given libp2p host
// and protocol ID, which must match the one used by the server.
// The Host must be correctly configured to be able to open streams
// to the server (addresses and keys in Peerstore etc.).
//
// The client returned will not be able to run any "local" requests (to its
// own peer ID) if a server is configured with the same Host becase libp2p
// hosts cannot open streams to themselves. For this, pass the server directly
// using NewClientWithServer.
func NewClient(h host.Host, p protocol.ID, opts ...ClientOption) *Client {
c := &Client{
host: h,
protocol: p,
}
for _, opt := range opts {
opt(c)
}
return c
}
// NewClientWithServer takes an additional RPC Server and returns a Client.
//
// Unlike the normal client, this one will be able to perform any requests to
// itself by using the given directly (and way more efficiently). It is
// assumed that Client and Server share the same libp2p host in this case.
func NewClientWithServer(h host.Host, p protocol.ID, s *Server, opts ...ClientOption) *Client {
c := NewClient(h, p, opts...)
c.server = s
return c
}
// ID returns the peer.ID of the host associated with this client.
func (c *Client) ID() peer.ID {
if c.host == nil {
return ""
}
return c.host.ID()
}
// Call performs an RPC call to a registered Server service and blocks until
// completed, returning any errors.
//
// The args parameter represents the service's method args and must be of
// exported or builtin type. The reply type will be used to provide a response
// and must be a pointer to an exported or builtin type. Otherwise a panic
// will occurr.
//
// If dest is empty ("") or matches the Client's host ID, it will
// attempt to use the local configured Server when possible.
func (c *Client) Call(
dest peer.ID,
svcName, svcMethod string,
args, reply interface{},
) error {
ctx := context.Background()
return c.CallContext(ctx, dest, svcName, svcMethod, args, reply)
}
// CallContext performs an RPC call to a registered Server service and blocks
// until completed, returning any errors. It takes a context which can be used
// to abort the call at any point.
//
// The args parameter represents the service's method args and must be of
// exported or builtin type. The reply type will be used to provide a response
// and must be a pointer to an exported or builtin type. Otherwise a panic
// will occurr.
//
// If dest is empty ("") or matches the Client's host ID, it will
// attempt to use the local configured Server when possible.
func (c *Client) CallContext(
ctx context.Context,
dest peer.ID,
svcName, svcMethod string,
args, reply interface{},
) error {
done := make(chan *Call, 1)
call := newCall(ctx, dest, svcName, svcMethod, args, reply, done)
go c.makeCall(call)
<-done
return call.getError()
}
// Go performs an RPC call asynchronously. The associated Call will be placed
// in the provided channel upon completion, holding any Reply or Errors.
//
// The args parameter represents the service's method args and must be of
// exported or builtin type. The reply type will be used to provide a response
// and must be a pointer to an exported or builtin type. Otherwise a panic
// will occurr.
//
// The provided done channel must be nil, or have capacity for 1 element
// at least, or a panic will be triggered.
//
// If dest is empty ("") or matches the Client's host ID, it will
// attempt to use the local configured Server when possible.
func (c *Client) Go(
dest peer.ID,
svcName, svcMethod string,
args, reply interface{},
done chan *Call,
) error {
ctx := context.Background()
return c.GoContext(ctx, dest, svcName, svcMethod, args, reply, done)
}
// GoContext performs an RPC call asynchronously. The provided context can be
// used to cancel the operation. The associated Call will be placed in the
// provided channel upon completion, holding any Reply or Errors.
//
// The args parameter represents the service's method args and must be of
// exported or builtin type. The reply type will be used to provide a response
// and must be a pointer to an exported or builtin type. Otherwise a panic
// will occurr.
//
// The provided done channel must be nil, or have capacity for 1 element
// at least, or a panic will be triggered.
//
// If dest is empty ("") or matches the Client's host ID, it will
// attempt to use the local configured Server when possible.
func (c *Client) GoContext(
ctx context.Context,
dest peer.ID,
svcName, svcMethod string,
args, reply interface{},
done chan *Call,
) error {
if done == nil {
done = make(chan *Call, 1)
} else {
if cap(done) == 0 {
panic("done channel has no capacity")
}
}
call := newCall(ctx, dest, svcName, svcMethod, args, reply, done)
go c.makeCall(call)
return nil
}
// MultiCall performs a CallContext() to multiple destinations, using the same
// service name, method and arguments. It will not return until all calls have
// done so. The contexts, destinations and replies must match in length and
// will be used in order (ctxs[i] is used for dests[i] which obtains
// replies[i] and error[i]).
//
// The calls will be triggered in parallel (with one goroutine for each).
func (c *Client) MultiCall(
ctxs []context.Context,
dests []peer.ID,
svcName, svcMethod string,
args interface{},
replies []interface{},
) []error {
ok := checkMatchingLengths(
len(ctxs),
len(dests),
len(replies),
)
if !ok {
panic("ctxs, dests and replies must match in length")
}
var wg sync.WaitGroup
errs := make([]error, len(dests))
for i := range dests {
wg.Add(1)
go func(i int) {
defer wg.Done()
err := c.CallContext(
ctxs[i],
dests[i],
svcName,
svcMethod,
args,
replies[i])
errs[i] = err
}(i)
}
wg.Wait()
return errs
}
// MultiGo performs a GoContext() call to multiple destinations, using the same
// service name, method and arguments. MultiGo will return as right after
// performing all the calls. See the Go() documentation for more information.
//
// The provided done channels must be nil, or have capacity for 1 element
// at least, or a panic will be triggered.
//
// The contexts, destinations, replies and done channels must match in length
// and will be used in order (ctxs[i] is used for dests[i] which obtains
// replies[i] with dones[i] signalled upon completion).
func (c *Client) MultiGo(
ctxs []context.Context,
dests []peer.ID,
svcName, svcMethod string,
args interface{},
replies []interface{},
dones []chan *Call,
) error {
ok := checkMatchingLengths(
len(ctxs),
len(dests),
len(replies),
len(dones),
)
if !ok {
panic("ctxs, dests, replies and dones must match in length")
}
for i := range ctxs {
c.GoContext(
ctxs[i],
dests[i],
svcName,
svcMethod,
args,
replies[i],
dones[i],
)
}
return nil
}
// Stream performs a streaming RPC call. It receives two arguments which both
// must be channels of exported or builtin types. The first is a channel from
// which objects are read and sent on the wire. The second is a channel to
// receive the replies from. Calling with the wrong types will cause a panic.
//
// The sending channel should be closed by the caller for successful
// completion of the call. The replies channel is closed by us when there is
// nothing else to receive (call finished or an error happened). The sending
// channel is drained in the background in case of error, so it is recommended
// that senders diligently close when an error happens to be able to free
// resources.
//
// The function only returns when the operation is finished successful (both
// channels are closed) or when an error has occurred.
func (c *Client) Stream(
ctx context.Context,
dest peer.ID,
svcName, svcMethod string,
argsChan interface{},
repliesChan interface{},
) error {
vArgsChan := reflect.ValueOf(argsChan)
vRepliesChan := reflect.ValueOf(repliesChan)
done := make(chan *Call, 1)
call := newStreamingCall(ctx, dest, svcName, svcMethod, vArgsChan, vRepliesChan, done)
go c.makeStream(call)
<-done
return call.getError()
}
// MultiStream performs parallel Stream() calls to multiple peers using a
// single arguments channel for arguments and a single replies channel that
// aggregates all replies. Errors from each destination are provided in the
// response. Channel types should be exported or builtin, otherwise a panic
// will be triggered.
//
// In order to replicate the argsChan values to several destinations and sed
// the replies into a single channel, intermediary channels for each call are
// created. These channels are buffered per the WithMultiStreamBufferSize()
// option. If the buffers is exausted for one of the sending or the receiving
// channels, the sending or receiving stalls. Therefore it is recommended to
// have enough buffering to allow that slower destinations do not delay
// everyone else.
func (c *Client) MultiStream(
ctx context.Context,
dests []peer.ID,
svcName, svcMethod string,
argsChan interface{},
repliesChan interface{},
) []error {
n := len(dests)
sID := ServiceID{svcName, svcMethod}
vArgsChan := reflect.ValueOf(argsChan)
vRepliesChan := reflect.ValueOf(repliesChan)
argsChanType := reflect.TypeOf(argsChan)
repliesChanType := reflect.TypeOf(repliesChan)
checkChanTypesValid(sID, vArgsChan, reflect.RecvDir)
checkChanTypesValid(sID, vRepliesChan, reflect.SendDir)
// Make slices of N channels of the same type as the argsChan and
// repliesChan. We will use them for every Stream() call. They are
// buffered per multiStreamBufferSize.
vArgsChannels := makeChanSliceOf(argsChanType, n, c.multiStreamBufferSize)
vRepliesChannels := makeChanSliceOf(repliesChanType, n, c.multiStreamBufferSize)
// Make slices of contexts and cancels. We will use them to cancel
// sending to channels when a Stream() call has failed.
teeCtxs := make([]context.Context, n)
teeCancels := make([]context.CancelFunc, n)
for i := 0; i < n; i++ {
teeCtxs[i], teeCancels[i] = context.WithCancel(ctx)
}
// To hold responses.
errs := make([]error, n)
var wg sync.WaitGroup
// First, launch N stream calls to every destination using the
// channels we created and everything else provided by the caller.
// Collect errors in errs, and if they happen, cancel associated
// context.
wg.Add(n)
for i := 0; i < n; i++ {
go func(i int) {
defer wg.Done()
err := c.Stream(
ctx,
dests[i],
svcName,
svcMethod,
vArgsChannels.Index(i).Interface(),
vRepliesChannels.Index(i).Interface(),
)
errs[i] = err
if err != nil {
teeCancels[i]() // cancel context for this so that we close the send channel
}
}(i)
}
// Second, "tee" anything received from the argsChan into the channels
// we created.
wg.Add(1)
go func() {
defer wg.Done()
// Close all sending channels when done.
defer func() {
for i := 0; i < n; i++ {
vArgsChannels.Index(i).Close()
}
}()
// Make a select with N cases (one per channel).
cases := make([]reflect.SelectCase, n)
for i := range cases {
cases[i].Dir = reflect.SelectSend
}
// While there is something to receive from the argsChan.
for {
arg, ok := vArgsChan.Recv()
if !ok {
return
}
// Setup cases. If the context for a channel has not
// been cancelled, prepare a send of the argument we
// read from argsChan. Otherwise set Chan to nil
// (effectively disables that case).
validCases := 0
for i := range cases {
cases[i].Send = arg
if teeCtxs[i].Err() == nil {
cases[i].Chan = vArgsChannels.Index(i)
validCases++
} else {
cases[i].Chan = reflect.ValueOf(nil)
}
}
if validCases == 0 { // all our ops failed.
go drainChannel(vArgsChan)
return
}
// Make a select for all cases and call it
// "validCases" times. This puts the arg value in all
// still available channels, potentially blocking if
// one of those channels has no buffer left.
for i := 0; i < validCases; i++ {
chosen, _, _ := reflect.Select(cases)
cases[chosen].Chan = reflect.ValueOf(nil) // ignore this case
}
// We continue reading from the channel.
// And repeat until no valid cases left.
// otherwise we continue just draining the channel
}
// if we are here argsChan has been closed.
}()
// Third, "multiplex" anything received from the argsChan into the
// channels we created.
wg.Add(1)
go func() {
defer wg.Done()
// Make a select with N cases (one per channel).
cases := make([]reflect.SelectCase, n)
for i := range cases {
cases[i].Dir = reflect.SelectRecv
cases[i].Chan = vRepliesChannels.Index(i)
}
validChannels := n
for validChannels > 0 {
chosen, v, ok := reflect.Select(cases)
if !ok {
cases[chosen].Chan = reflect.ValueOf(nil)
validChannels--
continue
}
vRepliesChan.Send(v)
}
// Close the response channels.
vRepliesChan.Close()
}()
// Wait for everyone to finish.
wg.Wait()
return errs
}
func makeChanSliceOf(typ reflect.Type, cap int, buffer int) reflect.Value {
chanSlice := reflect.MakeSlice(reflect.SliceOf(reflect.ChanOf(reflect.BothDir, typ.Elem())), 0, cap)
for i := 0; i < cap; i++ {
chanSlice = reflect.Append(
chanSlice,
reflect.MakeChan(reflect.ChanOf(reflect.BothDir, typ.Elem()), buffer),
)
}
return chanSlice
}
// returns true if all arguments are the same number.
func checkMatchingLengths(l ...int) bool {
if len(l) <= 1 {
return true
}
for i := 1; i < len(l); i++ {
if l[i-1] != l[i] {
return false
}
}
return true
}
// makeCall decides if a call can be performed. If it's a local
// call it will use the configured server if set.
func (c *Client) makeCall(call *Call) {
logger.Debugf("makeCall: %s", call.SvcID)
// Handle local RPC calls
if call.Dest == "" || c.host == nil || call.Dest == c.host.ID() {
logger.Debugf("local call: %s", call.SvcID)
if c.server == nil {
err := &clientError{"Cannot make local calls: server not set"}
call.doneWithError(err)
return
}
err := c.server.serverCall(call)
call.doneWithError(err)
return
}
// Handle remote RPC calls
if c.host == nil {
panic("no host set: cannot perform remote call")
}
if c.protocol == "" {
panic("no protocol set: cannot perform remote call")
}
c.send(call)
}
// send makes a REMOTE RPC call by initiating a libp2p stream to the
// destination and waiting for a response.
func (c *Client) send(call *Call) {
logger.Debug("sending remote call")
s, err := c.host.NewStream(call.ctx, call.Dest, c.protocol)
if err != nil {
call.doneWithError(newClientError(err))
return
}
go call.watchContextWithStream(s)
sWrap := wrapStream(s)
logger.Debugf("sending RPC %s to %s", call.SvcID, call.Dest)
if err := sWrap.enc.Encode(call.SvcID); err != nil {
call.doneWithError(newClientError(err))
s.Reset()
return
}
// In this case, we have a single argument in the channel.
if err := sWrap.enc.Encode(call.Args); err != nil {
call.doneWithError(newClientError(err))
s.Reset()
return
}
if err := sWrap.w.Flush(); err != nil {
call.doneWithError(newClientError(err))
s.Reset()
return
}
err = receiveResponse(sWrap, call)
if err != nil {
s.Reset()
return
}
s.Close()
}
// receiveResponse reads a response to an RPC call
func receiveResponse(s *streamWrap, call *Call) error {
logger.Debugf("waiting response for %s to %s", call.SvcID, call.Dest)
var resp Response
if err := s.dec.Decode(&resp); err != nil {
call.doneWithError(newClientError(err))
return err
}
if e := resp.Error; e != "" {
err := responseError(resp.ErrType, e)
call.setError(err)
// we still try to read the body if possible
}
if err := s.dec.Decode(call.Reply); err != nil && err != io.EOF {
call.doneWithError(newClientError(err))
return err
}
call.done()
return nil
}
// makeSteram performs a streaming call, either local or remote.
func (c *Client) makeStream(call *Call) {
logger.Debugf("stream: %s", call.SvcID)
// Handle local RPC calls
if call.Dest == "" || c.host == nil || call.Dest == c.host.ID() {
logger.Debugf("local call: %s", call.SvcID)
if c.server == nil {
err := &clientError{"Cannot make local calls: server not set"}
call.doneWithError(err)
return
}
err := c.server.serverStream(call)
if err != nil {
go drainChannel(call.StreamArgs)
}
call.doneWithError(err)
return
}
// Handle remote RPC calls
if c.host == nil {
panic("no host set: cannot perform remote call")
}
if c.protocol == "" {
panic("no protocol set: cannot perform remote call")
}
c.stream(call)
}
// stream makes a REMOTE RPC streaming call by initiating a libp2p stream to
// the destination, writing argument channel objects to it and reading the
// replies to the replies channel.
func (c *Client) stream(call *Call) {
logger.Debug("streaming remote call")
s, err := c.host.NewStream(call.ctx, call.Dest, c.protocol)
if err != nil {
call.doneWithError(newClientError(err))
go drainChannel(call.StreamArgs)
call.StreamReplies.Close()
return
}
go call.watchContextWithStream(s)
sWrap := wrapStream(s)
// Send the service ID first. This may return an authorization error
// for example.
logger.Debugf("sending stream-RPC %s to %s", call.SvcID, call.Dest)
if err := sWrap.enc.Encode(call.SvcID); err != nil {
call.doneWithError(newClientError(err))
s.Reset()
go drainChannel(call.StreamArgs)
call.StreamReplies.Close()
return
}
// Flush that so that we become ready to read on the other side.
if err := sWrap.w.Flush(); err != nil {
call.doneWithError(newClientError(err))
s.Reset()
go drainChannel(call.StreamArgs)
call.StreamReplies.Close()
return
}
// Now we need to start writing arguments and reading.
// Our context watcher will close the streams, we can therefore
// not worry about contexts closures in our goroutines.
var wg sync.WaitGroup
wg.Add(2)
// This goroutine sends things on the wire. It reads from the
// arguments channel, encodes the object and flushes it.
// Repeat until done or error.
// Arguments channel is drained on error.
go func() {
// Close stream for writing when done
defer wg.Done()
defer s.CloseWrite()
for {
v, ok := call.StreamArgs.Recv()
if !ok { // closed channel
return
}
if err := sWrap.enc.Encode(v); err != nil {
call.doneWithError(newClientError(err))
// closing the args channel is responsibility
// of the sender.
s.Reset()
go drainChannel(call.StreamArgs)
return
}
// Flush it
if err := sWrap.w.Flush(); err != nil {
call.doneWithError(newClientError(err))
s.Reset()
go drainChannel(call.StreamArgs)
return
}
}
}()
// This goroutine receives things from the wire. First it reads a
// Response (response can be considered reply "headers"). If it is an
// error, then it aborts. Then it reads a reply object and sends it on
// the reply channel.
go func() {
defer wg.Done()
defer call.StreamReplies.Close()
defer s.CloseRead()
for {
var resp Response
err := sWrap.dec.Decode(&resp)
if err == io.EOF {
return
}
if err != nil {
call.setError(newClientError(err))
s.Reset()
return
}
if resp.Error != "" {
call.setError(responseError(resp.ErrType, resp.Error))
s.Reset()
return
}
// Now decode the data
reply := reflect.New(call.StreamReplies.Type().Elem()).Elem().Interface()
err = sWrap.dec.Decode(&reply)
if err != nil {
call.setError(newClientError(err))
s.Reset()
return
}
// Put element
call.StreamReplies.Send(reflect.ValueOf(reply))
}
}()
// Wait for send/receive routines to finish, cleanup and then signal
// finalization of the Call.
wg.Wait()
s.Close()
call.done()
}