Yuri Schimke <******@****.***> 1690028931 +0100

   * of reads may not be immediately reflected on the algorithm's data structures. These structures
   * are guarded by a lock and operations are applied in batches to avoid lock contention. The
   * penalty of applying the batches is spread across threads so that the amortized cost is slightly
   * higher than performing just the operation without enforcing the capacity constraint.

	defer func() {
		if unlockOnDefer {
			nsUnlocker()
		}
	}()

	// Acquire lock
	if !opts.NoLock {
		lock := z.NewNSLock(bucket, object)
		lkctx, err := lock.GetRLock(ctx, globalOperationTimeout)
		if err != nil {
			return nil, err
		}
		ctx = lkctx.Context()
		nsUnlocker = func() { lock.RUnlock(lkctx) }
		unlockOnDefer = true
	}

	checkPrecondFn := opts.CheckPrecondFn

   * of reads may not be immediately reflected on the algorithm's data structures. These structures
   * are guarded by a lock and operations are applied in batches to avoid lock contention. The
   * penalty of applying the batches is spread across threads so that the amortized cost is slightly
   * higher than performing just the operation without enforcing the capacity constraint.

            session.setCurrentProject(step.project);
        }

        private Clock getClock(Object key) {
            return clocks.computeIfAbsent(key, p -> new Clock());
        }

        private void plan() {
            lock.writeLock().lock();
            try {
                Set<BuildStep> planSteps = plan.allSteps()

			nsUnlocker()
		}
	}()

	// Acquire lock
	if !opts.NoLock {
		lock := er.NewNSLock(bucket, object)
		lkctx, err := lock.GetRLock(ctx, globalOperationTimeout)
		if err != nil {
			return nil, err
		}
		ctx = lkctx.Context()

		// Release lock when the metadata is verified, and reader
		// is ready to be read.
		//
		// This is possible to be lock free because

		UserAgent:    r.UserAgent(),
		Host:         handlers.GetSourceIP(r),
	})
}

// PutBucketObjectLockConfigHandler - PUT Bucket object lock configuration.
// ----------
// Places an Object Lock configuration on the specified bucket. The rule
// specified in the Object Lock configuration will be applied by default
// to every new object placed in the specified bucket.

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

	ErrObjectLockConfigurationNotFound: {
		Code:           "ObjectLockConfigurationNotFoundError",
		Description:    "Object Lock configuration does not exist for this bucket",
		HTTPStatusCode: http.StatusNotFound,
	},
	ErrObjectLockConfigurationNotAllowed: {
		Code:           "InvalidBucketState",
		Description:    "Object Lock configuration cannot be enabled on existing buckets",
		HTTPStatusCode: http.StatusConflict,
	},

* Make addon-manager cross-platform and use it with hyperkube ([#25631](https://github.com/kubernetes/kubernetes/pull/25631), [@luxas](https://github.com/luxas))
* kubelet: Optionally, have kubelet exit if lock file contention is observed, using --exit-on-lock-contention flag ([#25596](https://github.com/kubernetes/kubernetes/pull/25596), [@derekparker](https://github.com/derekparker))