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29 lines
560 B
Go
29 lines
560 B
Go
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 262.
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// Package bank provides a concurrency-safe bank with one account.
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package bank
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//!+
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var (
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sema = make(chan struct{}, 1) // a binary semaphore guarding balance
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balance int
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)
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func Deposit(amount int) {
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sema <- struct{}{} // acquire token
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balance = balance + amount
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<-sema // release token
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}
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func Balance() int {
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sema <- struct{}{} // acquire token
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b := balance
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<-sema // release token
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return b
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}
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//!-
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