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expire.go

expire.go - Overview​

This file manages the expiration of objects stored in the Store. It includes functions to check if an object has expired, retrieve its expiry time, delete the expiry, and actively delete expired keys. It also handles setting the expiry with different conditions like NX, XX, GT, and LT.

Detailed Documentation​

Constants​

const (
	NX string = "NX"
	XX string = "XX"
	GT string = "GT"
	LT string = "LT"
)

These constants define the subcommands for setting expiry conditions.

  • NX: Set the expiration only if the key does not already have an expiration time.
  • XX: Set the expiration only if the key already has an expiration time.
  • GT: Set the expiration only if the new expiration time is greater than the current one.
  • LT: Set the expiration only if the new expiration time is less than the current one.

Function hasExpired​

func hasExpired(obj *object.Obj, store *Store) bool

Purpose: Checks if an object has expired.

Parameters:

  • obj (*object.Obj): The object to check.
  • store (*Store): The store where the object is stored.

Returns:

  • bool: Returns true if the object has expired, false otherwise.

Function GetExpiry​

func GetExpiry(obj *object.Obj, store *Store) (uint64, bool)

Purpose: Retrieves the expiry time of an object.

Parameters:

  • obj (*object.Obj): The object to get the expiry time for.
  • store (*Store): The store where the object is stored.

Returns:

  • uint64: The expiry time in milliseconds since the Unix epoch.
  • bool: true if the object has an expiry time, false otherwise.

Function DelExpiry​

func DelExpiry(obj *object.Obj, store *Store)

Purpose: Deletes the expiry time of an object.

Parameters:

  • obj (*object.Obj): The object to delete the expiry time for.
  • store (*Store): The store where the object is stored.

Returns:

  • None

Function expireSample​

func expireSample(store *Store) float32

Purpose: Samples a limited number of keys from the store and deletes the expired ones.

Parameters:

  • store (*Store): The store to sample from.

Returns:

  • float32: The fraction of expired keys in the sample.

Function DeleteExpiredKeys​

func DeleteExpiredKeys(store *Store)

Purpose: Deletes all expired keys in the store by repeatedly sampling until the fraction of expired keys is below a threshold.

Parameters:

  • store (*Store): The store to delete expired keys from.

Returns:

  • None

Function EvaluateAndSetExpiry​

func EvaluateAndSetExpiry(subCommands []string, newExpiry int64, key string,
	store *Store) (shouldSetExpiry bool, err error)

Purpose: Evaluates the given subcommands (NX, XX, GT, LT) and sets the expiry of a key based on the conditions.

Parameters:

  • subCommands ([]string): A slice of strings representing the subcommands.
  • newExpiry (int64): The new expiry time in seconds since the Unix epoch.
  • key (string): The key to set the expiry for.
  • store (*Store): The store where the object is stored.

Returns:

  • shouldSetExpiry (bool): true if the expiry should be set, false otherwise.
  • err (error): An error if there is an invalid combination of subcommands or an unsupported subcommand, nil otherwise.

Getting Started Relevance​