package exithook

import (
	"internal/runtime/atomic"
	_ "unsafe" // for linkname
)

// A Hook is a function to be run at program termination
// (when someone invokes os.Exit, or when main.main returns).
// Hooks are run in reverse order of registration:
// the first hook added is the last one run.
type Hook struct {
	F            func() // func to run

        if (systemProperties != null) {
            this.systemProperties = new Properties();
            synchronized (systemProperties) { // avoid concurrent modification if someone else sets/removes an unrelated
                // system property
                this.systemProperties.putAll(systemProperties);
            }
        } else {
            this.systemProperties = null;
        }

		select {
		case <-exited:
			t.Fatal("WaitGroup released group too soon")
		default:
		}
		wg2.Done()
	}
	for i := 0; i != n; i++ {
		<-exited // Will block if barrier fails to unlock someone.
	}
}

func TestWaitGroup(t *testing.T) {
	wg1 := &WaitGroup{}
	wg2 := &WaitGroup{}

	// Run the same test a few times to ensure barrier is in a proper state.
	for i := 0; i != 8; i++ {

        }
        registeredServices.add(service);
    }

    @Override
    public void acceptServiceReferences(List<? extends BuildServiceProvider<?, ?>> serviceReferences) {
        // someone already collected service references for us, just remember them
        consumedServices = serviceReferences;
    }

    @Override
    public boolean hasServiceReferences() {
        return consumedServices != null;

   * see calls in Google code that pass a null `dir` to a FilenameFilter.... So let's declare the
   * parameter as non-nullable (since passing null to a FilenameFilter is unsafe in general), but if
   * someone still manages to pass null, let's continue to have the method work.
   *
   * (PatternFilenameFilter is of course one of those classes that shouldn't be a publicly visible

   * see calls in Google code that pass a null `dir` to a FilenameFilter.... So let's declare the
   * parameter as non-nullable (since passing null to a FilenameFilter is unsafe in general), but if
   * someone still manages to pass null, let's continue to have the method work.
   *
   * (PatternFilenameFilter is of course one of those classes that shouldn't be a publicly visible

     * allowing the CAS below to succeed.
     */
    Thread currentThread = Thread.currentThread();
    if (!compareAndSet(null, currentThread)) {
      return; // someone else has run or is running.
    }

    boolean run = !isDone();
    T result = null;
    Throwable error = null;
    try {
      if (run) {
        result = runInterruptibly();
      }

		if r <= uintptr(len(block.data)) {
			return (*notInHeap)(unsafe.Pointer(&block.data[r-n]))
		}
	}

	// Try to install a new block.
	lock(&a.lock)

	// Check block again under the lock. Someone may
	// have gotten here first.
	block = (*traceRegionAllocBlock)(a.current.Load())
	if block != nil {
		r := block.off.Add(n)
		if r <= uintptr(len(block.data)) {
			unlock(&a.lock)

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		return err
	}

	// Remove contents & return first error.
	err = nil
	for {
		fd, err := Open(path)
		if err != nil {
			if IsNotExist(err) {
				// Already deleted by someone else.
				return nil
			}
			return err
		}

		const reqSize = 1024
		var names []string
		var readErr error

		for {
			numErr := 0
			names, readErr = fd.Readdirnames(reqSize)