go.uber.org/yarpc@v1.72.1/pkg/lifecycle/once_example_test.go (about)

     1  // Copyright (c) 2022 Uber Technologies, Inc.
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     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
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     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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    19  // THE SOFTWARE.
    20  
    21  package lifecycle_test
    22  
    23  import (
    24  	"fmt"
    25  
    26  	"go.uber.org/yarpc/pkg/lifecycle"
    27  )
    28  
    29  // Engine is an example of a type that uses a lifecycle.Once to synchronize its
    30  // lifecycle.
    31  type Engine struct {
    32  	once *lifecycle.Once
    33  }
    34  
    35  // NewEngine returns a lifecycle example.
    36  func NewEngine() (*Engine, error) {
    37  	return &Engine{
    38  		once: lifecycle.NewOnce(),
    39  	}, nil
    40  }
    41  
    42  // Start advances the engine to the running state (if it has not already done
    43  // so), printing "started".
    44  func (e *Engine) Start() error {
    45  	return e.once.Start(e.start)
    46  }
    47  
    48  func (e *Engine) start() error {
    49  	fmt.Printf("started\n")
    50  	return nil
    51  }
    52  
    53  // Stop advances the engine to the stopped state (if it has not already done
    54  // so), printing "stopped".
    55  func (e *Engine) Stop() error {
    56  	return e.once.Stop(e.stop)
    57  }
    58  
    59  func (e *Engine) stop() error {
    60  	fmt.Printf("stopped\n")
    61  	return nil
    62  }
    63  
    64  func Example() {
    65  	engine, err := NewEngine()
    66  	if err != nil {
    67  		fmt.Printf("%v\n", err)
    68  	}
    69  	go engine.Start() // might win race to start
    70  	engine.Start()    // blocks until started
    71  	defer engine.Stop()
    72  
    73  	// Output:
    74  	// started
    75  	// stopped
    76  }