--- title: TransactionUpdateBuilder summary: A builder-style API for configuring a transactional cache update. url: https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/cache/core/struct.TransactionUpdateBuilder/ --- **Kind:** Struct **Module:** [core](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/cache/core/) **Package:** fastly 0.13.1 **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1188 ```rust pub struct TransactionUpdateBuilder { /* private fields */ } ``` A builder-style API for configuring a transactional cache update. ## Methods ### age **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1209 ```rust 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. **Parameters** - `self`: `Self` - `age`: `Duration` **Returns** `Self` ### deliver_node_max_age **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1215 ```rust fn deliver_node_max_age(self, duration: Duration) -> Self ``` Sets the maximum time the cached item may live on a deliver node in a POP. **Parameters** - `self`: `Self` - `duration`: `Duration` **Returns** `Self` ### execute **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1247 ```rust fn execute(self) -> Result<(), CacheError> ``` Perform the update of the cache item's metadata. **Parameters** - `self`: `Self` **Returns** `Result<(), CacheError>` ### on_behalf_of **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1241 ```rust fn on_behalf_of(self, service: impl ToString) -> Self ``` Perform this update on behalf of another service, using its data store. #### Internal / Privileged This operation is privileged, and attempts to use this functionality without proper privileges will cause errors. If you are interested in having two or more of your services share the same cache, please talk to your Fastly account representative. While we have no plans to offer this ability widely -- this capability is only currently allowed for Fastly-internal services -- we may revisit this decision given sufficient customer input. **Parameters** - `self`: `Self` - `service`: `impl ToString` **Returns** `Self` ### stale_while_revalidate **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1221 ```rust 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`](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/cache/core/struct.Found/#method-is_usable) and [`Found::is_stale`](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/cache/core/struct.Found/#method-is_stale) can be used to determine the current state of a found item. The stale-while-revalidate period is `Duration::ZERO` by default. **Parameters** - `self`: `Self` - `duration`: `Duration` **Returns** `Self` ### surrogate_keys **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1227 ```rust fn surrogate_keys<'a>(self, keys: impl IntoIterator) -> Self ``` Sets the surrogate keys that can be used for purging this cached item. [Surrogate key purges](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/http/purge/fn.purge_surrogate_key/) 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](https://developer.fastly.com/learning/concepts/purging/#purge-all), waiting for the item's TTL to elapse, or overwriting the item with [`crate::cache::core::insert()`](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/cache/core/fn.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](https://docs.fastly.com/en/guides/purging-api-cache-with-surrogate-keys) for details. **Parameters** - `self`: `Self` - `keys`: `impl IntoIterator` **Returns** `Self` ### user_metadata **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1233 ```rust fn user_metadata(self, user_metadata: Bytes) -> Self ``` Sets the user-defined metadata to associate with the cached item. **Parameters** - `self`: `Self` - `user_metadata`: `Bytes` **Returns** `Self` ### vary_by **Source:** https://docs.rs/crate/fastly/0.13.1/source/src/cache/core.rs#1201 ```rust fn vary_by<'a>(self, headers: impl IntoIterator) -> 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()](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/cache/core/struct.TransactionLookupBuilder/#method-header) or [TransactionLookupBuilder::header_values()](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/cache/core/struct.TransactionLookupBuilder/#method-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](https://www.rfc-editor.org/rfc/rfc9110#section-12.5.5), 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. [`crate::cache::core::InsertBuilder::vary_by`](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/cache/core/struct.InsertBuilder/#method-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](https://www.fastly.com/blog/best-practices-using-vary-header) 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. **Parameters** - `self`: `Self` - `headers`: `impl IntoIterator` **Returns** `Self` ## Auto trait implementations - `Freeze` - `RefUnwindSafe` - `Send` - `Sync` - `Unpin` - `UnsafeUnpin` - `UnwindSafe` ## Blanket implementations - `Any` - `Borrow` - `BorrowMut` - `Downcast` - `DowncastSync` - `ErasedDestructor` - `From` - `Into` - `IntoEither` - `Same` - `TryFrom` - `TryInto`