Skip to Main Content
The Go Programming Language
book

The Go Programming Language

by Alan A. A. Donovan, Brian W. Kernighan
October 2015
Beginner to intermediate content levelBeginner to intermediate
400 pages
14h 44m
English
Addison-Wesley Professional
Content preview from The Go Programming Language

9.2 Mutual Exclusion: sync.Mutex

In Section 8.6, we used a buffered channel as a counting semaphore to ensure that no more than 20 goroutines made simultaneous HTTP requests. With the same idea, we can use a channel of capacity 1 to ensure that at most one goroutine accesses a shared variable at a time. A semaphore that counts only to 1 is called a binary semaphore.

gopl.io/ch9/bank2
var (
    sema    = make(chan struct{}, 1) // a binary semaphore guarding balance
    balance int
)

func Deposit(amount int) {
    sema <- struct{}{} // acquire token
    balance = balance + amount
    <-sema // release token
}

func Balance() int {
    sema <- struct{}{} // acquire token
    b := balance
    <-sema // release token
    return b
}

This pattern of mutual ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

The Rust Programming Language, 2nd Edition

The Rust Programming Language, 2nd Edition

Steve Klabnik, Carol Nichols
Programming Rust, 2nd Edition

Programming Rust, 2nd Edition

Jim Blandy, Jason Orendorff, Leonora F. S. Tindall

Publisher Resources

ISBN: 9780134190570Purchase book