Struct kismet_cache::CacheBuilder

pub struct CacheBuilder { /* fields omitted */ }

Construct a Cache with this builder. The resulting cache will always first access its write-side cache (if defined), and, on misses, will attempt to service Cache::get and Cache::touch calls by iterating over the read-only caches.

Implementations

impl CacheBuilder

pub fn new() -> Self

Returns a fresh empty builder.

pub fn consistency_checker(
    self,
    checker: impl Fn(&mut File, &mut File) -> Result<()> + Sync + Send + RefUnwindSafe + UnwindSafe + Sized + 'static
) -> Self

Sets the consistency checker function: when the function is provided, the ReadOnlyCache will keep searching after the first cache hit, and compare subsequent hits with the first one by calling checker. The checker function should return Ok(()) if the two files are compatible (identical), and Err otherwise.

Kismet will propagate the error on mismatch.

pub fn clear_consistency_checker(self) -> Self

Removes the consistency checker function, if any.

pub fn arc_consistency_checker(
    self,
    checker: Option<Arc<dyn Fn(&mut File, &mut File) -> Result<()> + Sync + Send + RefUnwindSafe + UnwindSafe>>
) -> Self

Sets the consistency checker function. None clears the checker function. See CacheBuilder::consistency_checker.

pub fn writer(
    self,
    path: impl AsRef<Path>,
    num_shards: usize,
    total_capacity: usize
) -> Self

Sets the read-write cache directory to path.

The read-write cache will be a plain cache directory if num_shards <= 1, and a sharded directory otherwise.

pub fn plain_writer(self, path: impl AsRef<Path>, capacity: usize) -> Self

Sets the read-write cache directory to a plain directory at path, with a target file count of up to capacity.

pub fn sharded_writer(
    self,
    path: impl AsRef<Path>,
    num_shards: usize,
    total_capacity: usize
) -> Self

Sets the read-write cache directory to a sharded directory at path, with num_shards subdirectories and a target file count of up to capacity for the entire cache.

pub fn auto_sync(self, sync: bool) -> Self

Sets whether files published read-write cache will be automatically flushed to disk with File::sync_all before sending them to the cache directory.

Defaults to true, for safety. Even when auto_sync is enabled, Kismet does not fsync cache directories; after a kernel or hardware crash, caches may partially revert to an older state, but should not contain incomplete files.

An application may want to disable auto_sync because it already synchronises files, or because the cache directories do not survive crashes: they might be erased after each boot, e.g., via tmpfiles.d, or tagged with a boot id.

pub fn reader(self, path: impl AsRef<Path>, num_shards: usize) -> Self

Adds a new read-only cache directory at path to the end of the cache builder’s search list.

Adds a plain cache directory if num_shards <= 1, and a sharded directory otherwise.

pub fn plain_reader(self, path: impl AsRef<Path>) -> Self

Adds a new plain (unsharded) read-only cache directory at path to the end of the cache builder’s search list.

pub fn sharded_reader(self, path: impl AsRef<Path>, num_shards: usize) -> Self

Adds a new sharded read-only cache directory at path to the end of the cache builder’s search list.

pub fn build(self) -> Cache

Returns a fresh Cache for the builder’s write cache and additional search list of read-only cache directories.

Trait Implementations

impl Debug for CacheBuilder

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

Formats the value using the given formatter.

impl Default for CacheBuilder

fn default() -> CacheBuilder

Returns the “default value” for a type.