logger.Info("bucketMetacache.findCache: bucket %s does not match this bucket %s", o.Bucket, b.bucket)
		debug.PrintStack()
		return metacache{}
	}

	// Grab a write lock, since we create one if we cannot find one.
	b.mu.Lock()
	defer b.mu.Unlock()

	// Check if exists already.
	if c, ok := b.caches[o.ID]; ok {
		c.lastHandout = time.Now()
		b.caches[o.ID] = c
		b.debugf("returning existing %v", o.ID)
		return c

type IAMStorageAPI interface {
	// The role of the read-write lock is to prevent go routines from
	// concurrently reading and writing the IAM storage. The (r)lock()
	// functions return the iamCache. The cache can be safely written to
	// only when returned by `lock()`.
	lock() *iamCache
	unlock()
	rlock() *iamCache
	runlock()
	getUsersSysType() UsersSysType

	activeConnections uint64
	sync.RWMutex
}

func (n *netPerfRX) Connect() {
	n.Lock()
	defer n.Unlock()
	n.activeConnections++
	atomic.StoreUint64(&n.RX, 0)
	n.lastToConnect = time.Now()
}

func (n *netPerfRX) Disconnect() {
	n.Lock()
	defer n.Unlock()
	n.activeConnections--
	if n.firstToDisconnect.IsZero() {
		n.RXSample = atomic.LoadUint64(&n.RX)

			db.Mux.RUnlock()
			return stmt, stmt.Error()
		}
	}
	db.Mux.RUnlock()

	// retry
	db.Mux.Lock()
	if db.Stmts != nil {
		if stmt, ok := db.Stmts.Get(query); ok && (!stmt.Transaction || isTransaction) {
			db.Mux.Unlock()
			return stmt, stmt.Error()
		}
	}

	return db.Stmts.New(ctx, query, isTransaction, conn, db.Mux)
}

 *
 * <ul>
 *   <li>for an unnested {@code lock()} and {@code unlock()}, a cycle detecting lock takes 38ns as
 *       opposed to the 24ns taken by a plain lock.
 *   <li>for nested locking, the cost increases with the depth of the nesting:
 *       <ul>
 *         <li>2 levels: average of 64ns per lock()/unlock()
 *         <li>3 levels: average of 77ns per lock()/unlock()
 *         <li>4 levels: average of 99ns per lock()/unlock()

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

/** Forwarding wrapper around a {@code Lock}. */
@J2ktIncompatible
@GwtIncompatible
abstract class ForwardingLock implements Lock {
  abstract Lock delegate();

  @Override
  public void lock() {
    delegate().lock();
  }

  @Override
  public void lockInterruptibly() throws InterruptedException {

		return
	}

	ri.mu.Lock()
	defer ri.mu.Unlock()

	if success {
		ri.Bucket = bucket
		ri.Object = info.Name
	}
	ri.countItem(info.Size, info.DeleteMarker, success, attempt)
}

func (ri *batchJobInfo) trackCurrentBucketBatch(bucket string, batch []ObjectInfo) {
	if ri == nil {
		return
	}

	ri.mu.Lock()
	defer ri.mu.Unlock()

	ri.Bucket = bucket

	globalAuthPluginMutex.Lock()
	defer globalAuthPluginMutex.Unlock()
	return globalAuthNPlugin
}

func newGlobalAuthZPluginFn() *polplugin.AuthZPlugin {
	globalAuthPluginMutex.Lock()
	defer globalAuthPluginMutex.Unlock()
	return globalAuthZPlugin
}

func setGlobalAuthNPlugin(authn *idplugin.AuthNPlugin) {
	globalAuthPluginMutex.Lock()
	globalAuthNPlugin = authn

				s.erasureDisks[m][n] = disk

				if disk.IsLocal() {
					globalLocalDrivesMu.Lock()
					if globalIsDistErasure {
						globalLocalSetDrives[s.poolIndex][m][n] = disk
					}
					globalLocalDrivesMap[disk.Endpoint().String()] = disk
					globalLocalDrivesMu.Unlock()
				}
			}
		}

		s.erasureDisksMu.Unlock()
	}

	return res, nil
}

}

func (c *ilmConfig) getExpirationWorkers() int {
	c.mu.RLock()
	defer c.mu.RUnlock()

	return c.cfg.ExpirationWorkers
}

func (c *ilmConfig) getTransitionWorkers() int {
	c.mu.RLock()
	defer c.mu.RUnlock()

	return c.cfg.TransitionWorkers
}

func (c *ilmConfig) update(cfg ilm.Config) {
	c.mu.Lock()
	defer c.mu.Unlock()

	c.cfg = cfg