Struct Cache 

pub struct Cache { /* private fields */ }

A directory of cached responses, keyed by URL.

Each URL is stored as <key>.bin (the bytes) and <key>.json (a CacheEntry without the bytes), where <key> is the 64-bit FNV-1a hash of the URL in hex. The metadata records the URL itself, so two URLs whose hashes collide read as a miss rather than as each other’s data. Each file is written whole to a temporary name and renamed, the metadata last. Nothing locks the cache: two writers of one URL may leave one’s body beside the other’s fetch time.

Implementations

impl Cache

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

A cache in dir, created on the first write.

pub fn dir(&self) -> &Path

The directory the cache lives in.

pub fn platform_dir() -> Option<PathBuf>

The standard place for hpr’s cache on this platform, or None if the environment names no home folder.

HPR_CACHE_DIR, when set and not empty, wins on every platform; it is used as given, so a relative path is taken from the current directory. Otherwise:

platform	folder
macOS	$HOME/Library/Caches/hpr-sim
Windows	%LOCALAPPDATA%\hpr-sim\cache
Linux and other Unix	$XDG_CACHE_HOME/hpr-sim, or $HOME/.cache/hpr-sim

XDG_CACHE_HOME counts only when it is an absolute path, as the XDG Base Directory Specification says. The folder is not created until the first write.

pub fn get(&self, url: &str) -> Result<Option<CacheEntry>, NetError>

The cached entry for url, or None if there is none.

Errors

NetError::Cache if a file exists but cannot be read; NetError::CorruptEntry if the metadata does not parse.

pub fn put( &self, url: &str, body: &[u8], fetched_at_s: u64, ) -> Result<(), NetError>

Stores body as url’s response, fetched at fetched_at_s.

Errors

NetError::Cache if the directory or a file cannot be written.

Trait Implementations

impl Clone for Cache

fn clone(&self) -> Cache

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Cache

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

Formats the value using the given formatter.