Struct zng_task::http::FileSystemCache

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pub struct FileSystemCache { /* private fields */ }
Expand description

A simple CacheDb implementation that uses a local directory.

§Implementation Details

A file lock is used to control data access, read operations use a shared lock so concurrent reads can happen, the set operation uses a exclusive lock for the duration of the body download, so subsequent requests for a caching resource will await until the cache is completed to return a body that will then read the cached data.

The set operation returns a body as soon as the entry is created, the body will receive data as it is downloaded and cached, in case of a cache error mid-download the cache entry is removed but the returned body will still download the rest of the data. In case of an error creating the entry the original body is always returned so the Client can continue with a normal download also.

The cache does not pull data, only data read by the returned body is written to the cache, dropping the body without reading to end cancels the cache entry.

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impl FileSystemCache

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pub fn new(dir: impl Into<PathBuf>) -> Result<Self>

Open the cache in dir or create it.

Trait Implementations§

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impl CacheDb for FileSystemCache

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fn clone_boxed(&self) -> Box<dyn CacheDb>

Dynamic clone.
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fn policy<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 CacheKey ) -> Pin<Box<dyn Future<Output = Option<CachePolicy>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Retrieves the cache-policy for the given key.
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fn set_policy<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 CacheKey, policy: CachePolicy ) -> Pin<Box<dyn Future<Output = bool> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Replaces the cache-policy for the given key. Read more
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fn body<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 CacheKey ) -> Pin<Box<dyn Future<Output = Option<Body>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Read/clone the cached body for the given key.
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fn set<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 CacheKey, policy: CachePolicy, body: Body ) -> Pin<Box<dyn Future<Output = Option<Body>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Caches the policy and body for the given key. Read more
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fn remove<'life0, 'life1, 'async_trait>( &'life0 self, key: &'life1 CacheKey ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Remove cached policy and body for the given key.
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fn purge<'life0, 'async_trait>( &'life0 self ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait,

Remove all cached entries that are not locked in a set* operation.
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fn prune<'life0, 'async_trait>( &'life0 self ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait,

Remove cache entries to reduce pressure. Read more
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impl Clone for FileSystemCache

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fn clone(&self) -> FileSystemCache

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more

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