├── License.txt ├── Readme.md ├── any.go ├── any2.go ├── error.go ├── example_test.go ├── go.mod └── value.go /License.txt: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. Definitions. 8 | 9 | "License" shall mean the terms and conditions for use, reproduction, 10 | and distribution as defined by Sections 1 through 9 of this document. 11 | 12 | "Licensor" shall mean the copyright owner or entity authorized by 13 | the copyright owner that is granting the License. 14 | 15 | "Legal Entity" shall mean the union of the acting entity and all 16 | other entities that control, are controlled by, or are under common 17 | control with that entity. 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The text should be enclosed in the appropriate 184 | comment syntax for the file format. We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. -------------------------------------------------------------------------------- /Readme.md: -------------------------------------------------------------------------------- 1 | # async/await 2 | 3 | Context cancellable futures in Go 4 | 5 | [![GoDoc](https://godoc.org/github.com/Gurpartap/async?status.svg)](https://godoc.org/github.com/Gurpartap/async) 6 | 7 | Provides a simple parallel execution primitive that we've all come to miss from Go: async/await futures. 8 | 9 | Each future is a straightforward implementation of a single go routine and a cancellable result channel. 10 | 11 | Accessing a future's result may require type casting from `interface{}`. 12 | 13 | ## Usage 14 | 15 | ```sh 16 | go get -u github.com/Gurpartap/async 17 | ``` 18 | 19 | 1. Create a `f := async.Any(...)`. 20 | 2. Do something else while it runs in the background. 21 | 3. `v, err := f.Await()` or `f.AwaitContext(ctx)` 22 | 4. Cast the resulting `value := v.(*MyType)`. 23 | 24 | ```go 25 | import ( 26 | "github.com/Gurpartap/async" 27 | ) 28 | 29 | future := async.Any(func() (interface{}, error) { 30 | return getUser() // a slow database or api call 31 | }) 32 | 33 | // do other stuff until we need user 34 | 35 | v, err := future.Await() 36 | value := v.(*User) 37 | ``` 38 | 39 | ```go 40 | // with timeout 41 | timeout := 5*time.Second 42 | ctx, _ := context.WithTimeout(context.Background(), timeout) 43 | v, err := future.Await() 44 | if err != nil { 45 | // handle if the err was a context timeout 46 | } 47 | value := v.(*User) 48 | ``` 49 | 50 | ## Available Futures 51 | 52 | The async package provides a bunch future types, each useful for a varying number of return params: 53 | 54 | For a value and an error: 55 | ```go 56 | func Any(func() (interface{}, error)) 57 | func Any(context.Context, func() (interface{}, error)) 58 | ``` 59 | 60 | For 2 values and an error: 61 | ```go 62 | func Any2(func() (interface{}, interface{}, error)) 63 | func Any2(context.Context, func() (interface{}, interface{}, error)) 64 | ``` 65 | 66 | For a value only: 67 | ```go 68 | func Value(func() interface{}) 69 | func Value(context.Context, func() interface{}) 70 | ``` 71 | 72 | For an error only: 73 | ```go 74 | func Err(func() error) 75 | func Err(context.Context, func() error) 76 | ``` 77 | 78 | ## Full Example 79 | 80 | ```go 81 | package async_test 82 | 83 | // ... 84 | // see the complete example code in example_test.go 85 | // ... 86 | 87 | func ExampleSync() { 88 | // if the db calls take 1 second each, the usual synchronous way 89 | // will take 4 seconds to get results 90 | 91 | user, err1 := db.GetUser() 92 | name, age, err2 := db.GetNameAndAge() 93 | location := db.GetLocation() 94 | err := db.SetName("Another Name") 95 | 96 | // use results 97 | } 98 | 99 | func ExampleAsync() { 100 | // execute the db calls asynchronously 101 | // and get results in 1 second 102 | 103 | anyFuture := async.Any(func() (interface{}, error) { 104 | return db.GetUser() 105 | }) 106 | any2Future := async.Any2(func() (interface{}, interface{}, error) { 107 | return db.GetNameAndAge() 108 | }) 109 | valueFuture := async.Value(func() interface{} { 110 | return db.GetLocation() 111 | }) 112 | errFuture := async.Err(func() error { 113 | return db.SetName("Another Name") 114 | }) 115 | 116 | // wait for results 117 | any, err1 := anyFuture.Await() 118 | user := any.(User) 119 | 120 | any1, any2, err2 := any2Future.Await() 121 | name := any1.(string) 122 | age := any2.(int) 123 | 124 | value := valueFuture.Await() 125 | location := value.(string) 126 | 127 | // cancellable 128 | ctx, _ := context.WithCancel(context.Background()) 129 | err := errFuture.AwaitContext(ctx) 130 | 131 | // use results 132 | } 133 | 134 | ``` 135 | 136 | ## License 137 | 138 | Copyright 2018 Gurpartap Singh 139 | 140 | Licensed under the Apache License, Version 2.0 (the "License"); 141 | you may not use this file except in compliance with the License. 142 | You may obtain a copy of the License at 143 | 144 | http://www.apache.org/licenses/LICENSE-2.0 145 | 146 | Unless required by applicable law or agreed to in writing, software 147 | distributed under the License is distributed on an "AS IS" BASIS, 148 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 149 | See the License for the specific language governing permissions and 150 | limitations under the License. 151 | -------------------------------------------------------------------------------- /any.go: -------------------------------------------------------------------------------- 1 | package async 2 | 3 | import ( 4 | "context" 5 | ) 6 | 7 | type AnyFuture interface { 8 | Await() (interface{}, error) 9 | AwaitContext(ctx context.Context) (interface{}, error) 10 | } 11 | 12 | type anyFuture struct { 13 | await func(ctx context.Context) (interface{}, error) 14 | } 15 | 16 | func (f anyFuture) Await() (interface{}, error) { 17 | return f.await(context.Background()) 18 | } 19 | 20 | func (f anyFuture) AwaitContext(ctx context.Context) (interface{}, error) { 21 | return f.await(ctx) 22 | } 23 | 24 | func Any(f func() (interface{}, error)) AnyFuture { 25 | var result interface{} 26 | var err error 27 | c := make(chan struct{}, 1) 28 | go func() { 29 | defer close(c) 30 | result, err = f() 31 | }() 32 | return anyFuture{ 33 | await: func(ctx context.Context) (interface{}, error) { 34 | select { 35 | case <-ctx.Done(): 36 | return nil, ctx.Err() 37 | case <-c: 38 | return result, err 39 | } 40 | }, 41 | } 42 | } 43 | -------------------------------------------------------------------------------- /any2.go: -------------------------------------------------------------------------------- 1 | package async 2 | 3 | import ( 4 | "context" 5 | ) 6 | 7 | type Any2Future interface { 8 | Await() (interface{}, interface{}, error) 9 | AwaitContext(ctx context.Context) (interface{}, interface{}, error) 10 | } 11 | 12 | type any2Future struct { 13 | await func(ctx context.Context) (interface{}, interface{}, error) 14 | } 15 | 16 | func (f any2Future) Await() (interface{}, interface{}, error) { 17 | return f.await(context.Background()) 18 | } 19 | 20 | func (f any2Future) AwaitContext(ctx context.Context) (interface{}, interface{}, error) { 21 | return f.await(ctx) 22 | } 23 | 24 | func Any2(f func() (interface{}, interface{}, error)) Any2Future { 25 | var result1 interface{} 26 | var result2 interface{} 27 | var err error 28 | c := make(chan struct{}, 1) 29 | go func() { 30 | defer close(c) 31 | result1, result2, err = f() 32 | }() 33 | return any2Future{ 34 | await: func(ctx context.Context) (interface{}, interface{}, error) { 35 | select { 36 | case <-ctx.Done(): 37 | return nil, nil, ctx.Err() 38 | case <-c: 39 | return result1, result2, err 40 | } 41 | }, 42 | } 43 | } 44 | -------------------------------------------------------------------------------- /error.go: -------------------------------------------------------------------------------- 1 | package async 2 | 3 | import ( 4 | "context" 5 | ) 6 | 7 | type ErrorFuture interface { 8 | Await() error 9 | AwaitContext(ctx context.Context) error 10 | } 11 | 12 | type errorFuture struct { 13 | await func(ctx context.Context) error 14 | } 15 | 16 | func (f errorFuture) Await() error { 17 | return f.await(context.Background()) 18 | } 19 | 20 | func (f errorFuture) AwaitContext(ctx context.Context) error { 21 | return f.await(ctx) 22 | } 23 | 24 | func Err(f func() error) ErrorFuture { 25 | var err error 26 | c := make(chan struct{}, 1) 27 | go func() { 28 | defer close(c) 29 | err = f() 30 | }() 31 | return errorFuture{ 32 | await: func(ctx context.Context) error { 33 | select { 34 | case <-ctx.Done(): 35 | return ctx.Err() 36 | case <-c: 37 | return err 38 | } 39 | }, 40 | } 41 | } 42 | -------------------------------------------------------------------------------- /example_test.go: -------------------------------------------------------------------------------- 1 | package async_test 2 | 3 | import ( 4 | "context" 5 | "errors" 6 | "fmt" 7 | "time" 8 | 9 | "github.com/Gurpartap/async" 10 | ) 11 | 12 | var db = &UsersStorage{ 13 | User: User{ 14 | Name: "Full Name", 15 | Age: 100, 16 | Location: "Mars", 17 | }, 18 | } 19 | 20 | type User struct { 21 | Name string 22 | Age int 23 | Location string 24 | } 25 | 26 | type UsersStorage struct { 27 | User User 28 | } 29 | 30 | func (s *UsersStorage) GetUser() (User, error) { 31 | time.Sleep(1 * time.Second) 32 | return s.User, nil 33 | } 34 | 35 | func (s *UsersStorage) GetLocation() string { 36 | time.Sleep(1 * time.Second) 37 | return s.User.Location 38 | } 39 | 40 | func (s *UsersStorage) GetNameAndAge() (string, int, error) { 41 | time.Sleep(1 * time.Second) 42 | return s.User.Name, s.User.Age, nil 43 | } 44 | 45 | func (s *UsersStorage) SetName(name string) error { 46 | time.Sleep(1 * time.Second) 47 | return errors.New("could not set name") 48 | } 49 | 50 | func ExampleSync() { 51 | // if the db calls take 1 second each, the usual synchronous way 52 | // will take 4 seconds to get results 53 | 54 | user, err1 := db.GetUser() 55 | name, age, err2 := db.GetNameAndAge() 56 | location := db.GetLocation() 57 | err := db.SetName("Another Name") 58 | 59 | // use results 60 | fmt.Printf("Any: user = %v, err = %v\n", user, err1) 61 | fmt.Printf("Any2: name = %s, age = %d, err = %v\n", name, age, err2) 62 | fmt.Printf("Value: location = %s\n", location) 63 | fmt.Printf("Err: err = %v\n\n", err) 64 | } 65 | 66 | func ExampleAsync() { 67 | // execute the db calls asynchronously 68 | // and get results in 1 second 69 | 70 | anyFuture := async.Any(func() (interface{}, error) { 71 | return db.GetUser() 72 | }) 73 | any2Future := async.Any2(func() (interface{}, interface{}, error) { 74 | return db.GetNameAndAge() 75 | }) 76 | valueFuture := async.Value(func() interface{} { 77 | return db.GetLocation() 78 | }) 79 | errFuture := async.Err(func() error { 80 | return db.SetName("Another Name") 81 | }) 82 | 83 | // wait for results 84 | any, err1 := anyFuture.Await() 85 | user := any.(User) 86 | 87 | any1, any2, err2 := any2Future.Await() 88 | name := any1.(string) 89 | age := any2.(int) 90 | 91 | value := valueFuture.Await() 92 | location := value.(string) 93 | 94 | // cancellable 95 | ctx, _ := context.WithCancel(context.Background()) 96 | err := errFuture.AwaitContext(ctx) 97 | 98 | // use results 99 | fmt.Printf("Any: user = %v, err = %v\n", user, err1) 100 | fmt.Printf("Any2: name = %s, age = %d, err = %v\n", name, age, err2) 101 | fmt.Printf("Value: location = %s\n", location) 102 | fmt.Printf("Err: err = %v\n\n", err) 103 | } 104 | -------------------------------------------------------------------------------- /go.mod: -------------------------------------------------------------------------------- 1 | module github.com/Gurpartap/async 2 | -------------------------------------------------------------------------------- /value.go: -------------------------------------------------------------------------------- 1 | package async 2 | 3 | import ( 4 | "context" 5 | ) 6 | 7 | type ValueFuture interface { 8 | Await() interface{} 9 | AwaitContext(ctx context.Context) interface{} 10 | } 11 | 12 | type valueFuture struct { 13 | await func(ctx context.Context) interface{} 14 | } 15 | 16 | func (f valueFuture) Await() interface{} { 17 | return f.await(context.Background()) 18 | } 19 | 20 | func (f valueFuture) AwaitContext(ctx context.Context) interface{} { 21 | return f.await(ctx) 22 | } 23 | 24 | func Value(f func() interface{}) ValueFuture { 25 | var result interface{} 26 | c := make(chan struct{}, 1) 27 | go func() { 28 | defer close(c) 29 | result = f() 30 | }() 31 | return valueFuture{ 32 | await: func(ctx context.Context) interface{} { 33 | select { 34 | case <-ctx.Done(): 35 | return ctx.Err() 36 | case <-c: 37 | return result 38 | } 39 | }, 40 | } 41 | } 42 | --------------------------------------------------------------------------------