Struct fastly::cache::core::TransactionUpdateBuilder

pub struct TransactionUpdateBuilder { /* private fields */ }

A builder-style API for configuring a transactional cache update.

Implementations

impl TransactionUpdateBuilder

pub fn vary_by<'a>( self, headers: impl IntoIterator<Item = &'a HeaderName> ) -> Self

Sets the list of headers that must match when looking up this cached item.

The header values must be provided by calling TransactionLookupBuilder::header() or TransactionLookupBuilder::header_values(). The header values may be a subset or superset of the header names supplied here.

Note: These headers are narrowly useful for implementing cache lookups incorporating the semantics of the HTTP Vary header, but the APIs in this module are not suitable for HTTP caching out-of-the-box. Future SDK releases will contain an HTTP Cache API.

The headers act as additional factors in object selection, and the choice of which headers to factor in is determined during insertion, via e.g. InsertBuilder::vary_by. A lookup will succeed when there is at least one cached item that matches lookup’s cache key, and all of the lookup’s headers included in the cache items’ vary_by list match the corresponding headers in that cached item.

A typical example is a cached HTTP response, where the request had an Accept-Encoding header. In that case, the origin server may or may not decide on a given encoding, and whether that same response is suitable for a request with a different (or missing) Accept-Encoding header is determined by whether Accept-Encoding is listed in Vary header in the origin’s response.

pub fn age(self, age: Duration) -> Self

Sets the updated age of the cached item, to be used in freshness calculations.

The updated age is Duration::ZERO by default.

pub fn stale_while_revalidate(self, duration: Duration) -> Self

Sets the stale-while-revalidate period for the cached item, which is the time for which the item can be safely used despite being considered stale.

Having a stale-while-revalidate period provides a signal that the cache should be updated (or its contents otherwise revalidated for freshness) asynchronously, while the stale cached item continues to be used, rather than blocking on updating the cached item. The methods Found::is_usable and Found::is_stale can be used to determine the current state of a found item.

The stale-while-revalidate period is Duration::ZERO by default.

pub fn surrogate_keys<'a>(self, keys: impl IntoIterator<Item = &'a str>) -> Self

Sets the surrogate keys that can be used for purging this cached item.

Surrogate key purges are the only means to purge specific items from the cache. At least one surrogate key must be set in order to remove an item without performing a purge-all, waiting for the item’s TTL to elapse, or overwriting the item with insert().

Surrogate keys must contain only printable ASCII characters (those between 0x21 and 0x7E, inclusive). Any invalid keys will be ignored.

See the Fastly surrogate keys guide for details.

pub fn user_metadata(self, user_metadata: Bytes) -> Self

Sets the user-defined metadata to associate with the cached item.

pub fn execute(self) -> Result<(), CacheError>

Perform the update of the cache item’s metadata.