github.com/YoungNK/go-ethereum@v1.9.7/event/example_subscription_test.go (about)

     1  // Copyright 2016 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package event_test
    18  
    19  import (
    20  	"fmt"
    21  
    22  	"github.com/ethereum/go-ethereum/event"
    23  )
    24  
    25  func ExampleNewSubscription() {
    26  	// Create a subscription that sends 10 integers on ch.
    27  	ch := make(chan int)
    28  	sub := event.NewSubscription(func(quit <-chan struct{}) error {
    29  		for i := 0; i < 10; i++ {
    30  			select {
    31  			case ch <- i:
    32  			case <-quit:
    33  				fmt.Println("unsubscribed")
    34  				return nil
    35  			}
    36  		}
    37  		return nil
    38  	})
    39  
    40  	// This is the consumer. It reads 5 integers, then aborts the subscription.
    41  	// Note that Unsubscribe waits until the producer has shut down.
    42  	for i := range ch {
    43  		fmt.Println(i)
    44  		if i == 4 {
    45  			sub.Unsubscribe()
    46  			break
    47  		}
    48  	}
    49  	// Output:
    50  	// 0
    51  	// 1
    52  	// 2
    53  	// 3
    54  	// 4
    55  	// unsubscribed
    56  }