x-DeltaFIFO 与 Indexer关系¶

type DeltaFIFO struct {
    // lock/cond protects access to 'items' and 'queue'.
    lock sync.RWMutex
    cond sync.Cond

    // `items` maps a key to a Deltas.
    // Each such Deltas has at least one Delta.
    items map[string]Deltas

    // `queue` maintains FIFO order of keys for consumption in Pop().
    // There are no duplicates in `queue`.
    // A key is in `queue` if and only if it is in `items`.
    queue []string

    // populated is true if the first batch of items inserted by Replace() has been populated
    // or Delete/Add/Update/AddIfNotPresent was called first.
    populated bool
    // initialPopulationCount is the number of items inserted by the first call of Replace()
    initialPopulationCount int

    // keyFunc is used to make the key used for queued item
    // insertion and retrieval, and should be deterministic.
    keyFunc KeyFunc

    // knownObjects list keys that are "known" --- affecting Delete(),
    // Replace(), and Resync()
    knownObjects KeyListerGetter

    // Used to indicate a queue is closed so a control loop can exit when a queue is empty.
    // Currently, not used to gate any of CRED operations.
    closed bool

    // emitDeltaTypeReplaced is whether to emit the Replaced or Sync
    // DeltaType when Replace() is called (to preserve backwards compat).
    emitDeltaTypeReplaced bool
}

// state of the object before it was deleted.
type Delta struct {
    Type   DeltaType
    Object interface{}
}

// Deltas is a list of one or more 'Delta's to an individual object.
// The oldest delta is at index 0, the newest delta is the last one.
type Deltas []Delta

type cache struct {
    // cacheStorage bears the burden of thread safety for the cache
    cacheStorage ThreadSafeStore
    // keyFunc is used to make the key for objects stored in and retrieved from items, and
    // should be deterministic.
    keyFunc KeyFunc
}

// threadSafeMap implements ThreadSafeStore
type threadSafeMap struct {
    lock  sync.RWMutex
    items map[string]interface{}

    // indexers maps a name to an IndexFunc
    indexers Indexers
    // indices maps a name to an Index
    indices Indices
}