storage

Documentation

Overview

Interfaces for database-related operations.

Index

• func Everything(runtime.Object) bool
• func NamespaceKeyFunc(prefix string, obj runtime.Object) (string, error)
• func NoNamespaceKeyFunc(prefix string, obj runtime.Object) (string, error)
• func ParseWatchResourceVersion(resourceVersion, kind string) (uint64, error)
• type Cacher
  • func NewCacher(config CacherConfig) *Cacher
  • func (c *Cacher) Backends() []string
  • func (c *Cacher) Codec() runtime.Codec
  • func (c *Cacher) Create(key string, obj, out runtime.Object, ttl uint64) error
  • func (c *Cacher) Delete(key string, out runtime.Object) error
  • func (c *Cacher) Get(key string, objPtr runtime.Object, ignoreNotFound bool) error
  • func (c *Cacher) GetToList(key string, listObj runtime.Object) error
  • func (c *Cacher) GuaranteedUpdate(key string, ptrToType runtime.Object, ignoreNotFound bool, ...) error
  • func (c *Cacher) LastSyncResourceVersion() (uint64, error)
  • func (c *Cacher) List(key string, listObj runtime.Object) error
  • func (c *Cacher) ListFromMemory(key string, listObj runtime.Object) error
  • func (c *Cacher) Set(key string, obj, out runtime.Object, ttl uint64) error
  • func (c *Cacher) Versioner() Versioner
  • func (c *Cacher) Watch(key string, resourceVersion uint64, filter FilterFunc) (watch.Interface, error)
  • func (c *Cacher) WatchList(key string, resourceVersion uint64, filter FilterFunc) (watch.Interface, error)
• type CacherConfig
• type FilterFunc
• type Interface
• type ResponseMeta
• type SimpleUpdateFunc
• type UpdateFunc
  • func SimpleUpdate(fn SimpleUpdateFunc) UpdateFunc
• type Versioner

Functions

func Everything

func Everything(runtime.Object) bool

Everything is a FilterFunc which accepts all objects.

func NamespaceKeyFunc

func NamespaceKeyFunc(prefix string, obj runtime.Object) (string, error)

func NoNamespaceKeyFunc

func NoNamespaceKeyFunc(prefix string, obj runtime.Object) (string, error)

func ParseWatchResourceVersion

func ParseWatchResourceVersion(resourceVersion, kind string) (uint64, error)

ParseWatchResourceVersion takes a resource version argument and converts it to the etcd version we should pass to helper.Watch(). Because resourceVersion is an opaque value, the default watch behavior for non-zero watch is to watch the next value (if you pass "1", you will see updates from "2" onwards).

Types

type Cacher

type Cacher struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

Cacher is responsible for serving WATCH and LIST requests for a given resource from its internal cache and updating its cache in the background based on the underlying storage contents. Cacher implements storage.Interface (although most of the calls are just delegated to the underlying storage).

func NewCacher

func NewCacher(config CacherConfig) *Cacher

Create a new Cacher responsible from service WATCH and LIST requests from its internal cache and updating its cache in the background based on the given configuration.

func (*Cacher) Backends

func (c *Cacher) Backends() []string

Implements storage.Interface.

func (*Cacher) Codec

func (c *Cacher) Codec() runtime.Codec

Implements storage.Interface.

func (*Cacher) Create

func (c *Cacher) Create(key string, obj, out runtime.Object, ttl uint64) error

Implements storage.Interface.

func (*Cacher) Delete

func (c *Cacher) Delete(key string, out runtime.Object) error

Implements storage.Interface.

func (*Cacher) Get

func (c *Cacher) Get(key string, objPtr runtime.Object, ignoreNotFound bool) error

Implements storage.Interface.

func (*Cacher) GetToList

func (c *Cacher) GetToList(key string, listObj runtime.Object) error

Implements storage.Interface.

func (*Cacher) GuaranteedUpdate

func (c *Cacher) GuaranteedUpdate(key string, ptrToType runtime.Object, ignoreNotFound bool, tryUpdate UpdateFunc) error

Implements storage.Interface.

func (*Cacher) LastSyncResourceVersion

func (c *Cacher) LastSyncResourceVersion() (uint64, error)

Returns resource version to which the underlying cache is synced.

func (*Cacher) List

func (c *Cacher) List(key string, listObj runtime.Object) error

Implements storage.Interface.

func (*Cacher) ListFromMemory

func (c *Cacher) ListFromMemory(key string, listObj runtime.Object) error

ListFromMemory implements list operation (the same signature as List method) but it serves the contents from memory. Current we cannot use ListFromMemory() instead of List(), because it only guarantees eventual consistency (e.g. it's possible for Get called right after Create to return not-exist, before the change is propagate). TODO: We may consider changing to use ListFromMemory in the future, but this requires wider discussion as an "api semantic change".

func (*Cacher) Set

func (c *Cacher) Set(key string, obj, out runtime.Object, ttl uint64) error

Implements storage.Interface.

func (*Cacher) Versioner

func (c *Cacher) Versioner() Versioner

Implements storage.Interface.

func (*Cacher) Watch

func (c *Cacher) Watch(key string, resourceVersion uint64, filter FilterFunc) (watch.Interface, error)

Implements storage.Interface.

func (*Cacher) WatchList

func (c *Cacher) WatchList(key string, resourceVersion uint64, filter FilterFunc) (watch.Interface, error)

Implements storage.Interface.

type CacherConfig

type CacherConfig struct {
	// Maximum size of the history cached in memory.
	CacheCapacity int

	// An underlying storage.Interface.
	Storage Interface

	// An underlying storage.Versioner.
	Versioner Versioner

	// The Cache will be caching objects of a given Type and assumes that they
	// are all stored under ResourcePrefix directory in the underlying database.
	Type           interface{}
	ResourcePrefix string

	// KeyFunc is used to get a key in the underyling storage for a given object.
	KeyFunc func(runtime.Object) (string, error)

	// NewList is a function that creates new empty object storing a list of
	// objects of type Type.
	NewListFunc func() runtime.Object

	// Cacher will be stopped when the StopChannel will be closed.
	StopChannel <-chan struct{}
}

CacherConfig contains the configuration for a given Cache.

type FilterFunc

type FilterFunc func(obj runtime.Object) bool

FilterFunc is a predicate which takes an API object and returns true iff the object should remain in the set.

type Interface

type Interface interface {
	// Returns list of servers addresses of the underyling database.
	// TODO: This method is used only in a single place. Consider refactoring and getting rid
	// of this method from the interface.
	Backends() []string

	// Returns Versioner associated with this interface.
	Versioner() Versioner

	// Create adds a new object at a key unless it already exists. 'ttl' is time-to-live
	// in seconds (0 means forever). If no error is returned and out is not nil, out will be
	// set to the read value from database.
	Create(key string, obj, out runtime.Object, ttl uint64) error

	// Set marshals obj via json and stores in database under key. Will do an atomic update
	// if obj's ResourceVersion field is set. 'ttl' is time-to-live in seconds (0 means forever).
	// If no error is returned and out is not nil, out will be set to the read value from database.
	Set(key string, obj, out runtime.Object, ttl uint64) error

	// Delete removes the specified key and returns the value that existed at that spot.
	Delete(key string, out runtime.Object) error

	// Watch begins watching the specified key. Events are decoded into API objects,
	// and any items passing 'filter' are sent down to returned watch.Interface.
	// resourceVersion may be used to specify what version to begin watching
	// (e.g. reconnecting without missing any updates).
	Watch(key string, resourceVersion uint64, filter FilterFunc) (watch.Interface, error)

	// WatchList begins watching the specified key's items. Items are decoded into API
	// objects and any item passing 'filter' are sent down to returned watch.Interface.
	// resourceVersion may be used to specify what version to begin watching
	// (e.g. reconnecting without missing any updates).
	WatchList(key string, resourceVersion uint64, filter FilterFunc) (watch.Interface, error)

	// Get unmarshals json found at key into objPtr. On a not found error, will either
	// return a zero object of the requested type, or an error, depending on ignoreNotFound.
	// Treats empty responses and nil response nodes exactly like a not found error.
	Get(key string, objPtr runtime.Object, ignoreNotFound bool) error

	// GetToList unmarshals json found at key and opaque it into *List api object
	// (an object that satisfies the runtime.IsList definition).
	GetToList(key string, listObj runtime.Object) error

	// List unmarshalls jsons found at directory defined by key and opaque them
	// into *List api object (an object that satisfies runtime.IsList definition).
	List(key string, listObj runtime.Object) error

	// GuaranteedUpdate keeps calling 'tryUpdate()' to update key 'key' (of type 'ptrToType')
	// retrying the update until success if there is index conflict.
	// Note that object passed to tryUpdate may change acress incovations of tryUpdate() if
	// other writers are simultaneously updateing it, to tryUpdate() needs to take into account
	// the current contents of the object when deciding how the update object should look.
	//
	// Example:
	//
	// s := /* implementation of Interface */
	// err := s.GuaranteedUpdate(
	//     "myKey", &MyType{}, true,
	//     func(input runtime.Object, res ResponseMeta) (runtime.Object, *uint64, error) {
	//       // Before each incovation of the user defined function, "input" is reset to
	//       // current contents for "myKey" in database.
	//       curr := input.(*MyType)  // Guaranteed to succeed.
	//
	//       // Make the modification
	//       curr.Counter++
	//
	//       // Return the modified object - return an error to stop iterating. Return
	//       // a uint64 to alter the TTL on the object, or nil to keep it the same value.
	//       return cur, nil, nil
	//    }
	// })
	GuaranteedUpdate(key string, ptrToType runtime.Object, ignoreNotFound bool, tryUpdate UpdateFunc) error

	// Codec provides access to the underlying codec being used by the implementation.
	Codec() runtime.Codec
}

Interface offers a common interface for object marshaling/unmarshling operations and hides all the storage-related operations behind it.

type ResponseMeta

type ResponseMeta struct {
	// TTL is the time to live of the node that contained the returned object. It may be
	// zero or negative in some cases (objects may be expired after the requested
	// expiration time due to server lag).
	TTL int64
	// Expiration is the time at which the node that contained the returned object will expire and be deleted.
	// This can be nil if there is no expiration time set for the node.
	Expiration *time.Time
	// The resource version of the node that contained the returned object.
	ResourceVersion uint64
}

ResponseMeta contains information about the database metadata that is associated with an object. It abstracts the actual underlying objects to prevent coupling with concrete database and to improve testability.

type SimpleUpdateFunc

type SimpleUpdateFunc func(runtime.Object) (runtime.Object, error)

type UpdateFunc

type UpdateFunc func(input runtime.Object, res ResponseMeta) (output runtime.Object, ttl *uint64, err error)

Pass an UpdateFunc to Interface.GuaranteedUpdate to make an update that is guaranteed to succeed. See the comment for GuaranteedUpdate for more details.

func SimpleUpdate

func SimpleUpdate(fn SimpleUpdateFunc) UpdateFunc

SimpleUpdateFunc converts SimpleUpdateFunc into UpdateFunc

type Versioner

type Versioner interface {
	// UpdateObject sets storage metadata into an API object. Returns an error if the object
	// cannot be updated correctly. May return nil if the requested object does not need metadata
	// from database.
	UpdateObject(obj runtime.Object, expiration *time.Time, resourceVersion uint64) error
	// UpdateList sets the resource version into an API list object. Returns an error if the object
	// cannot be updated correctly. May return nil if the requested object does not need metadata
	// from database.
	UpdateList(obj runtime.Object, resourceVersion uint64) error
	// ObjectResourceVersion returns the resource version (for persistence) of the specified object.
	// Should return an error if the specified object does not have a persistable version.
	ObjectResourceVersion(obj runtime.Object) (uint64, error)
}

Versioner abstracts setting and retrieving metadata fields from database response onto the object ot list.