Struct DefaultCacheStorage

pub struct DefaultCacheStorage(/* private fields */);

The default cache storage implementation.

Layout

This storage implementation uses the following directory structure:

<root>/
├─ <storage-version>/
│  ├─ responses/
│  │  ├─ <key>
│  │  ├─ <key>
│  │  ├─ ...
│  ├─ content/
│  │  ├─ <digest>
│  │  ├─ <digest>
│  │  ├─ ...
│  ├─ tmp/

Where <root> is the root storage directory, <storage-version> is a constant that changes when the directory layout changes (currently v1), <key> is supplied by the cache, and <digest> is the calculated digest of a response body.

The responses directory

The responses directory contains a file for each cached response.

The file is a bincode-serialized CachedResponse that contains information about the response, including the response body content digest.

Response file locking

Advisory file locks are obtained on a response file as the cache entries are read and updated.

This is used to coordinate access to the storage via this library; it does not protect against external modifications to the storage.

The content directory

The content directory contains a file for each cached response body.

The file name is the digest of the response body contents.

Currently the blake3 hash algorithm is used for calculating response body digests.

The tmp directory

The tmp directory is used for temporarily storing response bodies as they are saved to the cache.

The content digest of the response is calculated as the response is written into temporary storage.

Once the response body has been fully read, the temporary file is atomically renamed to its content directory location; if the content already exists, the temporary file is deleted.

Integrity

This storage implementation does not provide strong guarantees on the integrity of the stored response bodies.

If the storage is externally modified, the modification will go undetected and the modified response bodies will be served.

Fault tolerance

If an error occurs while updating a cache entry with DefaultCacheStorage::put, a future DefaultCacheStorage::get call will treat the entry as not present.

Implementations

impl DefaultCacheStorage

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

Constructs a new default cache storage with the given

Trait Implementations

impl CacheStorage for DefaultCacheStorage

async fn get<B: HttpBody>(&self, key: &str) -> Result<Option<StoredResponse<B>>>

Gets a previously stored response for the given response key.

async fn put( &self, key: &str, parts: &Parts, policy: &CachePolicy, digest: &str, ) -> Result<()>

Puts a response with an existing content digest into the storage for the given response key.

async fn put_with_body<B: HttpBody>( &self, key: &str, parts: &Parts, policy: &CachePolicy, body: B, ) -> Result<(Body<B>, String)>

Puts a response with supplied body into the storage for the given response key.

async fn delete(&self, key: &str) -> Result<()>

Deletes a previously cached response for the given response key.

fn body_path(&self, digest: &str) -> PathBuf

Gets the path to a response body for the given content digest.