Simpler code to cache value

[dgageot]

No description provided.

[docker-agent]

Assessment: 🟡 NEEDS ATTENTION

One confirmed medium-severity data race introduced by the refactor.

[docker-agent]

[MEDIUM] Data race: unsynchronised write to Get in ResetForTests() vs concurrent reads

ResetForTests() assigns a fresh sync.OnceValue to the package-level variable Get without any synchronisation. Meanwhile, parallel tests (e.g. TestHeaders uses t.Parallel()) or the HTTP client may be reading Get to call it. Writing to a shared variable from one goroutine while another goroutine reads it is a data race under the Go memory model — go test -race will flag it.

The old implementation avoided this by holding mu inside ResetForTests() before clearing cached. The new implementation has no equivalent protection on the variable itself.

Suggested fix: protect the variable with a sync.RWMutex, use sync/atomic (atomic.Value or a pointer), or — simplest for a test-only reset — guard the write and read with a mutex:

var getMu sync.RWMutex
var getOnce = sync.OnceValue(get)

func Get() string {
    getMu.RLock()
    f := getOnce
    getMu.RUnlock()
    return f()
}

func ResetForTests() {
    getMu.Lock()
    getOnce = sync.OnceValue(get)
    getMu.Unlock()
}