import java.util.Iterator;
import javax.annotation.CheckForNull;

/**
 * A function from {@code A} to {@code B} with an associated <i>reverse</i> function from {@code B}
 * to {@code A}; used for converting back and forth between <i>different representations of the same
 * information</i>.
 *
 * <h3>Invertibility</h3>
 *
 * <p>The reverse operation <b>may</b> be a strict <i>inverse</i> (meaning that {@code

	// Test on a copy
	// cleanup is the only one deleting caches.
	caches, _ := b.cloneCaches()

	for id, cache := range caches {
		if !cache.worthKeeping() {
			b.debugf("cache %s not worth keeping", id)
			remove[id] = struct{}{}
			continue
		}
		if cache.id != id {
			logger.Info("cache ID mismatch %s != %s", id, cache.id)
			remove[id] = struct{}{}
			continue
		}

				i++
				// Determine if os.NotExist error is because of
				// baseDir's parent being present, retry it once such
				// that the MkdirAll is retried once for the parent
				// of dirPath.
				// Because it is worth a retry to skip a different
				// baseDir which is slightly higher up the depth.
				nbaseDir := path.Dir(baseDir)
				if baseDir != "" && nbaseDir != "" && nbaseDir != SlashSeparator {
					baseDir = nbaseDir
				}

	recursive    bool       `msg:"rec"`
	dataVersion  uint8      `msg:"v"`
}

func (m *metacache) finished() bool {
	return !m.ended.IsZero()
}

// worthKeeping indicates if the cache by itself is worth keeping.
func (m *metacache) worthKeeping() bool {
	if m == nil {
		return false
	}
	cache := m
	switch {
	case !cache.finished() && time.Since(cache.lastUpdate) > metacacheMaxRunningAge:

 * when there is a specific reason to prioritize memory over CPU.
 *
 * @author Louis Wasserman
 */
@J2ktIncompatible // no support for access-order mode in LinkedHashMap delegate
@GwtIncompatible // not worth using in GWT for now
@ElementTypesAreNonnullByDefault
class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
    extends CompactHashMap<K, V> {

import java.util.Iterator;
import javax.annotation.CheckForNull;

/**
 * A function from {@code A} to {@code B} with an associated <i>reverse</i> function from {@code B}
 * to {@code A}; used for converting back and forth between <i>different representations of the same
 * information</i>.
 *
 * <h3>Invertibility</h3>
 *
 * <p>The reverse operation <b>may</b> be a strict <i>inverse</i> (meaning that {@code

 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible // not worth using in GWT for now
@ElementTypesAreNonnullByDefault
class CompactLinkedHashSet<E extends @Nullable Object> extends CompactHashSet<E> {

  /** Creates an empty {@code CompactLinkedHashSet} instance. */

 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible // not worth using in GWT for now
@ElementTypesAreNonnullByDefault
class CompactLinkedHashSet<E extends @Nullable Object> extends CompactHashSet<E> {

  /** Creates an empty {@code CompactLinkedHashSet} instance. */

 * when there is a specific reason to prioritize memory over CPU.
 *
 * @author Louis Wasserman
 */
@J2ktIncompatible // no support for access-order mode in LinkedHashMap delegate
@GwtIncompatible // not worth using in GWT for now
@ElementTypesAreNonnullByDefault
class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
    extends CompactHashMap<K, V> {

forth). A Go function called by C code may take C pointers as arguments,
and it may store non-pointer data, C pointers, or Go pointers to pinned
memory through those pointers. It may not store a Go pointer to unpinned
memory in memory pointed to by a C pointer (which again, implies that it
may not store a string, slice, channel, and so forth). A Go function