-
-
Notifications
You must be signed in to change notification settings - Fork 3.9k
/
stream.go
566 lines (475 loc) · 12.4 KB
/
stream.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
package fx
import (
"sort"
"sync"
"github.com/zeromicro/go-zero/core/collection"
"github.com/zeromicro/go-zero/core/lang"
"github.com/zeromicro/go-zero/core/threading"
)
const (
defaultWorkers = 16
minWorkers = 1
)
type (
rxOptions struct {
unlimitedWorkers bool
workers int
}
// FilterFunc defines the method to filter a Stream.
FilterFunc func(item any) bool
// ForAllFunc defines the method to handle all elements in a Stream.
ForAllFunc func(pipe <-chan any)
// ForEachFunc defines the method to handle each element in a Stream.
ForEachFunc func(item any)
// GenerateFunc defines the method to send elements into a Stream.
GenerateFunc func(source chan<- any)
// KeyFunc defines the method to generate keys for the elements in a Stream.
KeyFunc func(item any) any
// LessFunc defines the method to compare the elements in a Stream.
LessFunc func(a, b any) bool
// MapFunc defines the method to map each element to another object in a Stream.
MapFunc func(item any) any
// Option defines the method to customize a Stream.
Option func(opts *rxOptions)
// ParallelFunc defines the method to handle elements parallelly.
ParallelFunc func(item any)
// ReduceFunc defines the method to reduce all the elements in a Stream.
ReduceFunc func(pipe <-chan any) (any, error)
// WalkFunc defines the method to walk through all the elements in a Stream.
WalkFunc func(item any, pipe chan<- any)
// A Stream is a stream that can be used to do stream processing.
Stream struct {
source <-chan any
}
)
// Concat returns a concatenated Stream.
func Concat(s Stream, others ...Stream) Stream {
return s.Concat(others...)
}
// From constructs a Stream from the given GenerateFunc.
func From(generate GenerateFunc) Stream {
source := make(chan any)
threading.GoSafe(func() {
defer close(source)
generate(source)
})
return Range(source)
}
// Just converts the given arbitrary items to a Stream.
func Just(items ...any) Stream {
source := make(chan any, len(items))
for _, item := range items {
source <- item
}
close(source)
return Range(source)
}
// Range converts the given channel to a Stream.
func Range(source <-chan any) Stream {
return Stream{
source: source,
}
}
// AllMach returns whether all elements of this stream match the provided predicate.
// May not evaluate the predicate on all elements if not necessary for determining the result.
// If the stream is empty then true is returned and the predicate is not evaluated.
func (s Stream) AllMach(predicate func(item any) bool) bool {
for item := range s.source {
if !predicate(item) {
// make sure the former goroutine not block, and current func returns fast.
go drain(s.source)
return false
}
}
return true
}
// AnyMach returns whether any elements of this stream match the provided predicate.
// May not evaluate the predicate on all elements if not necessary for determining the result.
// If the stream is empty then false is returned and the predicate is not evaluated.
func (s Stream) AnyMach(predicate func(item any) bool) bool {
for item := range s.source {
if predicate(item) {
// make sure the former goroutine not block, and current func returns fast.
go drain(s.source)
return true
}
}
return false
}
// Buffer buffers the items into a queue with size n.
// It can balance the producer and the consumer if their processing throughput don't match.
func (s Stream) Buffer(n int) Stream {
if n < 0 {
n = 0
}
source := make(chan any, n)
go func() {
for item := range s.source {
source <- item
}
close(source)
}()
return Range(source)
}
// Concat returns a Stream that concatenated other streams
func (s Stream) Concat(others ...Stream) Stream {
source := make(chan any)
go func() {
group := threading.NewRoutineGroup()
group.Run(func() {
for item := range s.source {
source <- item
}
})
for _, each := range others {
each := each
group.Run(func() {
for item := range each.source {
source <- item
}
})
}
group.Wait()
close(source)
}()
return Range(source)
}
// Count counts the number of elements in the result.
func (s Stream) Count() (count int) {
for range s.source {
count++
}
return
}
// Distinct removes the duplicated items base on the given KeyFunc.
func (s Stream) Distinct(fn KeyFunc) Stream {
source := make(chan any)
threading.GoSafe(func() {
defer close(source)
keys := make(map[any]lang.PlaceholderType)
for item := range s.source {
key := fn(item)
if _, ok := keys[key]; !ok {
source <- item
keys[key] = lang.Placeholder
}
}
})
return Range(source)
}
// Done waits all upstreaming operations to be done.
func (s Stream) Done() {
drain(s.source)
}
// Filter filters the items by the given FilterFunc.
func (s Stream) Filter(fn FilterFunc, opts ...Option) Stream {
return s.Walk(func(item any, pipe chan<- any) {
if fn(item) {
pipe <- item
}
}, opts...)
}
// First returns the first item, nil if no items.
func (s Stream) First() any {
for item := range s.source {
// make sure the former goroutine not block, and current func returns fast.
go drain(s.source)
return item
}
return nil
}
// ForAll handles the streaming elements from the source and no later streams.
func (s Stream) ForAll(fn ForAllFunc) {
fn(s.source)
// avoid goroutine leak on fn not consuming all items.
go drain(s.source)
}
// ForEach seals the Stream with the ForEachFunc on each item, no successive operations.
func (s Stream) ForEach(fn ForEachFunc) {
for item := range s.source {
fn(item)
}
}
// Group groups the elements into different groups based on their keys.
func (s Stream) Group(fn KeyFunc) Stream {
groups := make(map[any][]any)
for item := range s.source {
key := fn(item)
groups[key] = append(groups[key], item)
}
source := make(chan any)
go func() {
for _, group := range groups {
source <- group
}
close(source)
}()
return Range(source)
}
// Head returns the first n elements in p.
func (s Stream) Head(n int64) Stream {
if n < 1 {
panic("n must be greater than 0")
}
source := make(chan any)
go func() {
for item := range s.source {
n--
if n >= 0 {
source <- item
}
if n == 0 {
// let successive method go ASAP even we have more items to skip
close(source)
// why we don't just break the loop, and drain to consume all items.
// because if breaks, this former goroutine will block forever,
// which will cause goroutine leak.
drain(s.source)
}
}
// not enough items in s.source, but we need to let successive method to go ASAP.
if n > 0 {
close(source)
}
}()
return Range(source)
}
// Last returns the last item, or nil if no items.
func (s Stream) Last() (item any) {
for item = range s.source {
}
return
}
// Map converts each item to another corresponding item, which means it's a 1:1 model.
func (s Stream) Map(fn MapFunc, opts ...Option) Stream {
return s.Walk(func(item any, pipe chan<- any) {
pipe <- fn(item)
}, opts...)
}
// Max returns the maximum item from the underlying source.
func (s Stream) Max(less LessFunc) any {
var max any
for item := range s.source {
if max == nil || less(max, item) {
max = item
}
}
return max
}
// Merge merges all the items into a slice and generates a new stream.
func (s Stream) Merge() Stream {
var items []any
for item := range s.source {
items = append(items, item)
}
source := make(chan any, 1)
source <- items
close(source)
return Range(source)
}
// Min returns the minimum item from the underlying source.
func (s Stream) Min(less LessFunc) any {
var min any
for item := range s.source {
if min == nil || less(item, min) {
min = item
}
}
return min
}
// NoneMatch returns whether all elements of this stream don't match the provided predicate.
// May not evaluate the predicate on all elements if not necessary for determining the result.
// If the stream is empty then true is returned and the predicate is not evaluated.
func (s Stream) NoneMatch(predicate func(item any) bool) bool {
for item := range s.source {
if predicate(item) {
// make sure the former goroutine not block, and current func returns fast.
go drain(s.source)
return false
}
}
return true
}
// Parallel applies the given ParallelFunc to each item concurrently with given number of workers.
func (s Stream) Parallel(fn ParallelFunc, opts ...Option) {
s.Walk(func(item any, pipe chan<- any) {
fn(item)
}, opts...).Done()
}
// Reduce is a utility method to let the caller deal with the underlying channel.
func (s Stream) Reduce(fn ReduceFunc) (any, error) {
return fn(s.source)
}
// Reverse reverses the elements in the stream.
func (s Stream) Reverse() Stream {
var items []any
for item := range s.source {
items = append(items, item)
}
// reverse, official method
for i := len(items)/2 - 1; i >= 0; i-- {
opp := len(items) - 1 - i
items[i], items[opp] = items[opp], items[i]
}
return Just(items...)
}
// Skip returns a Stream that skips size elements.
func (s Stream) Skip(n int64) Stream {
if n < 0 {
panic("n must not be negative")
}
if n == 0 {
return s
}
source := make(chan any)
go func() {
for item := range s.source {
n--
if n >= 0 {
continue
} else {
source <- item
}
}
close(source)
}()
return Range(source)
}
// Sort sorts the items from the underlying source.
func (s Stream) Sort(less LessFunc) Stream {
var items []any
for item := range s.source {
items = append(items, item)
}
sort.Slice(items, func(i, j int) bool {
return less(items[i], items[j])
})
return Just(items...)
}
// Split splits the elements into chunk with size up to n,
// might be less than n on tailing elements.
func (s Stream) Split(n int) Stream {
if n < 1 {
panic("n should be greater than 0")
}
source := make(chan any)
go func() {
var chunk []any
for item := range s.source {
chunk = append(chunk, item)
if len(chunk) == n {
source <- chunk
chunk = nil
}
}
if chunk != nil {
source <- chunk
}
close(source)
}()
return Range(source)
}
// Tail returns the last n elements in p.
func (s Stream) Tail(n int64) Stream {
if n < 1 {
panic("n should be greater than 0")
}
source := make(chan any)
go func() {
ring := collection.NewRing(int(n))
for item := range s.source {
ring.Add(item)
}
for _, item := range ring.Take() {
source <- item
}
close(source)
}()
return Range(source)
}
// Walk lets the callers handle each item, the caller may write zero, one or more items base on the given item.
func (s Stream) Walk(fn WalkFunc, opts ...Option) Stream {
option := buildOptions(opts...)
if option.unlimitedWorkers {
return s.walkUnlimited(fn, option)
}
return s.walkLimited(fn, option)
}
func (s Stream) walkLimited(fn WalkFunc, option *rxOptions) Stream {
pipe := make(chan any, option.workers)
go func() {
var wg sync.WaitGroup
pool := make(chan lang.PlaceholderType, option.workers)
for item := range s.source {
// important, used in another goroutine
val := item
pool <- lang.Placeholder
wg.Add(1)
// better to safely run caller defined method
threading.GoSafe(func() {
defer func() {
wg.Done()
<-pool
}()
fn(val, pipe)
})
}
wg.Wait()
close(pipe)
}()
return Range(pipe)
}
func (s Stream) walkUnlimited(fn WalkFunc, option *rxOptions) Stream {
pipe := make(chan any, option.workers)
go func() {
var wg sync.WaitGroup
for item := range s.source {
// important, used in another goroutine
val := item
wg.Add(1)
// better to safely run caller defined method
threading.GoSafe(func() {
defer wg.Done()
fn(val, pipe)
})
}
wg.Wait()
close(pipe)
}()
return Range(pipe)
}
// UnlimitedWorkers lets the caller use as many workers as the tasks.
func UnlimitedWorkers() Option {
return func(opts *rxOptions) {
opts.unlimitedWorkers = true
}
}
// WithWorkers lets the caller customize the concurrent workers.
func WithWorkers(workers int) Option {
return func(opts *rxOptions) {
if workers < minWorkers {
opts.workers = minWorkers
} else {
opts.workers = workers
}
}
}
// buildOptions returns a rxOptions with given customizations.
func buildOptions(opts ...Option) *rxOptions {
options := newOptions()
for _, opt := range opts {
opt(options)
}
return options
}
// drain drains the given channel.
func drain(channel <-chan any) {
for range channel {
}
}
// newOptions returns a default rxOptions.
func newOptions() *rxOptions {
return &rxOptions{
workers: defaultWorkers,
}
}