Struct FactoryContext 

pub struct FactoryContext<V> { /* private fields */ }

Context passed to a factory, carrying stale-value information and the mutable options for the value being produced.

Implementations

impl<V> FactoryContext<V>

pub fn key(&self) -> &str

The (prefixed) cache key being produced.

pub fn options_mut(&mut self) -> &mut EntryOptions

The options for the value being produced. Mutate these to adapt the caching of this specific value (e.g. shorten the duration for an empty result). This is adaptive caching.

pub fn options(&self) -> &EntryOptions

The options for the value being produced.

pub fn adapt<F>(&mut self, f: F)

where F: FnOnce(EntryOptions) -> EntryOptions,

Adapts the options for the value being produced using the chainable builder methods — the ergonomic way to do adaptive caching:

ctx.adapt(|o| o.with_duration(Duration::from_secs(5)));

pub fn has_stale_value(&self) -> bool

true if a previously-cached (now stale) value is available.

pub fn stale_value(&self) -> Option<&V>

The previously-cached (now stale) value, if any.

pub fn stale_etag(&self) -> Option<&str>

The ETag of the stale value, for issuing a conditional request.

pub fn stale_last_modified(&self) -> Option<Timestamp>

The LastModified of the stale value, for issuing a conditional request.

pub fn set_tags<I, S>(&mut self, tags: I)

where I: IntoIterator<Item = S>, S: AsRef<str>,

Sets the tags for the value being produced (adaptive tagging). Overrides the tags passed to the get_or_set call.

pub fn value(self, value: V) -> FactoryProduct<V>

Produces a new value, cached with the current (possibly adapted) options.

pub fn modified(self, value: V) -> ModifiedBuilder<V>

Begins producing a modified value, allowing an ETag/LastModified (and tags) to be attached for future conditional refreshes.

pub fn fail(&self, message: impl Into<String>) -> FactoryError

Signals a factory failure, returning a FactoryError to return as Err. Triggers the fail-safe path.

impl<V: Clone> FactoryContext<V>

pub fn not_modified(self) -> Result<FactoryProduct<V>, FactoryError>

Signals that the resource has not changed (e.g. an HTTP 304): the stale value is reused as the fresh result and its expiration is bumped using the current options. Fails if there is no stale value to reuse.

Trait Implementations

impl<V: Debug> Debug for FactoryContext<V>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.