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1 // Copyright 2015 The LUCI Authors. All rights reserved. | 1 // Copyright 2015 The LUCI Authors. All rights reserved. |
2 // Use of this source code is governed under the Apache License, Version 2.0 | 2 // Use of this source code is governed under the Apache License, Version 2.0 |
3 // that can be found in the LICENSE file. | 3 // that can be found in the LICENSE file. |
4 | 4 |
5 package parallel | 5 package parallel |
6 | 6 |
7 import ( | 7 import ( |
8 "github.com/luci/luci-go/common/errors" | 8 "github.com/luci/luci-go/common/errors" |
9 ) | 9 ) |
10 | 10 |
11 // WorkPool creates a fixed-size pool of worker goroutines. A supplied generator | 11 // WorkPool creates a fixed-size pool of worker goroutines. A supplied generator |
12 // method creates task functions and passes them through to the work pool. | 12 // method creates task functions and passes them through to the work pool. |
13 // | 13 // |
14 // WorkPool will use at most workers goroutines to execute the supplied tasks. | 14 // WorkPool will use at most workers goroutines to execute the supplied tasks. |
15 // If workers is <= 0, WorkPool will be unbounded and behave like FanOutIn. | 15 // If workers is <= 0, WorkPool will be unbounded and behave like FanOutIn. |
16 // | 16 // |
17 // WorkPool blocks until all the generator completes and all workers have | 17 // WorkPool blocks until all the generator completes and all workers have |
18 // finished their tasks. | 18 // finished their tasks. |
19 func WorkPool(workers int, gen func(chan<- func() error)) error { | 19 func WorkPool(workers int, gen func(chan<- func() error)) error { |
20 » return errors.MultiErrorFromErrors(Run(workers, gen)) | 20 » return MultiErrorFromErrors(Run(workers, gen)) |
21 } | 21 } |
22 | 22 |
23 // FanOutIn is useful to quickly parallelize a group of tasks. | 23 // FanOutIn is useful to quickly parallelize a group of tasks. |
24 // | 24 // |
25 // You pass it a function which is expected to push simple `func() error` | 25 // You pass it a function which is expected to push simple `func() error` |
26 // closures into the provided chan. Each function will be executed in parallel | 26 // closures into the provided chan. Each function will be executed in parallel |
27 // and their error results will be collated. | 27 // and their error results will be collated. |
28 // | 28 // |
29 // The function blocks until all functions are executed, and an | 29 // The function blocks until all functions are executed, and an |
30 // errors.MultiError is returned if one or more of your fan-out tasks failed, | 30 // errors.MultiError is returned if one or more of your fan-out tasks failed, |
31 // otherwise this function returns nil. | 31 // otherwise this function returns nil. |
32 // | 32 // |
33 // This function is equivalent to WorkPool(0, gen). | 33 // This function is equivalent to WorkPool(0, gen). |
34 func FanOutIn(gen func(chan<- func() error)) error { | 34 func FanOutIn(gen func(chan<- func() error)) error { |
35 return WorkPool(0, gen) | 35 return WorkPool(0, gen) |
36 } | 36 } |
37 | |
38 // MultiErrorFromErrors takes an error-channel, blocks on it, and returns | |
39 // a MultiError for any errors pushed to it over the channel, or nil if | |
40 // all the errors were nil. | |
41 func MultiErrorFromErrors(ch <-chan error) error { | |
Vadim Sh.
2017/06/23 00:32:16
does it have to be public? Anyone uses it besides
| |
42 if ch == nil { | |
43 return nil | |
44 } | |
45 ret := errors.MultiError(nil) | |
46 for e := range ch { | |
47 if e == nil { | |
48 continue | |
49 } | |
50 ret = append(ret, e) | |
51 } | |
52 if len(ret) == 0 { | |
53 return nil | |
54 } | |
55 return ret | |
56 } | |
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