RWMutex in Go

Many readers or one writer, when reads dominate.

type Table struct {
    mu   sync.RWMutex
    rows map[string]int
}

func NewTable() *Table {
    return &Table{rows: make(map[string]int)}
}

func (t *Table) Set(key string, value int) {
    t.mu.Lock()
    defer t.mu.Unlock()
    t.rows[key] = value
}

func (t *Table) Get(key string) (int, bool) {
    t.mu.RLock()
    defer t.mu.RUnlock()
    value, ok := t.rows[key]
    return value, ok
}

How it works

1. RLock may be held concurrently; Lock excludes everyone.
2. Always unlock with defer, so a return cannot skip it.
3. Embedding the mutex in the struct keeps them together.

Keywords and builtins used here

• bool
• defer
• func
• int
• make
• map
• return
• string
• struct
• type

The run, in numbers

Lines

21

Characters to type

354

Tokens

124

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 71 seconds.

Type this snippet

Step 2 of 5 in Synchronization, step 15 of 25 in Concurrency.

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