if err == nil {
		err = ErrClosedPipe
	}
	p.rerr.Store(err)
	p.once.Do(func() { close(p.done) })
	return nil
}

func (p *pipe) write(b []byte) (n int, err error) {
	select {
	case <-p.done:
		return 0, p.writeCloseError()
	default:
		p.wrMu.Lock()
		defer p.wrMu.Unlock()
	}

	for once := true; once || len(b) > 0; once = false {
		select {
		case p.wrCh <- b:
			nw := <-p.rdCh
			b = b[nw:]

//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname systemRoots
var (
	once           sync.Once
	systemRootsMu  sync.RWMutex
	systemRoots    *CertPool
	systemRootsErr error
	fallbacksSet   bool
)

func systemRootsPool() *CertPool {
	once.Do(initSystemRoots)
	systemRootsMu.RLock()
	defer systemRootsMu.RUnlock()
	return systemRoots
}

func initSystemRoots() {

import (
	"fmt"
	"log"
	"net/http"
	"net/http/cgi"
	"os"
	"os/exec"
	"path/filepath"
	"sync"
)

type fossilHandler struct {
	once          sync.Once
	fossilPath    string
	fossilPathErr error
}

func (h *fossilHandler) Available() bool {
	h.once.Do(func() {
		h.fossilPath, h.fossilPathErr = exec.LookPath("fossil")
	})
	return h.fossilPathErr == nil
}

package mime

import (
	"reflect"
	"strings"
	"sync"
	"testing"
)

func setMimeInit(fn func()) (cleanup func()) {
	once = sync.Once{}
	testInitMime = fn
	return func() {
		testInitMime = nil
		once = sync.Once{}
	}
}

func clearMimeTypes() {
	setMimeTypes(map[string]string{}, map[string]string{})
}

func setType(ext, typ string) {
	if !strings.HasPrefix(ext, ".") {

	case isClosedChan(p.writeDeadline.wait()):
		return 0, os.ErrDeadlineExceeded
	}

	p.wrMu.Lock() // Ensure entirety of b is written together
	defer p.wrMu.Unlock()
	for once := true; once || len(b) > 0; once = false {
		select {
		case p.wrTx <- b:
			nw := <-p.wrRx
			b = b[nw:]
			n += nw
		case <-p.localDone:
			return n, io.ErrClosedPipe
		case <-p.remoteDone:

                compositeSubstitute()
            }
        }
    }

    def "build with discovered substitutions that is not required for dependency substitution is configured only once"() {
        given:
        dependency "org.test:buildB:1.0"

        includeBuild buildB
        includeBuild buildC

        when:
        buildC.buildFile << """
            println 'Configured buildC'

var (
	onceFunc = sync.OnceFunc(func() {})

	onceFuncOnce sync.Once
)

func doOnceFunc() {
	onceFuncOnce.Do(func() {})
}

func BenchmarkOnceFunc(b *testing.B) {
	b.Run("v=Once", func(b *testing.B) {
		b.ReportAllocs()
		for i := 0; i < b.N; i++ {
			// The baseline is direct use of sync.Once.
			doOnceFunc()
		}
	})
	b.Run("v=Global", func(b *testing.B) {

	// The returned value can no longer be modified once returned.
	// Should be set before calling Get().
	updateFn func(ctx context.Context) (T, error)

	// ttl for a cached value.
	ttl time.Duration

	opts Opts

	// Once can be used to initialize values for lazy initialization.
	// Should be set before calling Get().
	Once sync.Once

	// Managed values.
	val          atomic.Pointer[T]

        when:
        registry.get("id", TestDeploymentHandle)
        then:
        def e = thrown(IllegalStateException)
        e.message == "Cannot modify deployment handles once the registry has been stopped."
    }

    def "cannot register a handle once the registry is stopped" () {
        given:
        registry.stop()

        when:
        registry.start("id", DeploymentRegistry.ChangeBehavior.NONE, TestDeploymentHandle)

	var timeCh <-chan time.Time
	doneCh := ctx.Done()

	if !sliding {
		timeCh = t.C()
	}

	// if immediate is true the condition is
	// guaranteed to be executed at least once,
	// if we haven't requested immediate execution, delay once
	if immediate {
		if ok, err := func() (bool, error) {
			defer runtime.HandleCrash()
			return condition(ctx)
		}(); err != nil || ok {
			return err
		}
	}

	if sliding {