74 lines
1.9 KiB
Go
74 lines
1.9 KiB
Go
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// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package event_test
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import (
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"fmt"
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"github.com/ethereum/go-ethereum/event"
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)
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func ExampleFeed_acknowledgedEvents() {
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// This example shows how the return value of Send can be used for request/reply
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// interaction between event consumers and producers.
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var feed event.Feed
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type ackedEvent struct {
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i int
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ack chan<- struct{}
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}
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// Consumers wait for events on the feed and acknowledge processing.
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done := make(chan struct{})
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defer close(done)
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for i := 0; i < 3; i++ {
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ch := make(chan ackedEvent, 100)
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sub := feed.Subscribe(ch)
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go func() {
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defer sub.Unsubscribe()
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for {
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select {
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case ev := <-ch:
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fmt.Println(ev.i) // "process" the event
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ev.ack <- struct{}{}
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case <-done:
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return
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}
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}
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}()
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}
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// The producer sends values of type ackedEvent with increasing values of i.
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// It waits for all consumers to acknowledge before sending the next event.
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for i := 0; i < 3; i++ {
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acksignal := make(chan struct{})
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n := feed.Send(ackedEvent{i, acksignal})
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for ack := 0; ack < n; ack++ {
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<-acksignal
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}
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}
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// Output:
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// 0
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// 0
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// 0
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// 1
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// 1
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// 1
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// 2
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// 2
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// 2
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}
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