Struct Previews 

pub struct Previews { /* private fields */ }

Cached, isolated conversions (one per server, part of AppState).

Implementations

impl Previews

pub fn new(vault: &Vault, limits: PreviewLimits) -> Previews

pub async fn render<T, F>(&self, key: &str, work: F) -> AppResult<T>

where T: Send + 'static, F: FnOnce() -> T + Send + 'static,

Runs CPU-bound work on a derived cache entry – drawing a thumbnail, composing an assembly preview – off the async runtime: at most MAX_RENDERS at a time and one at a time per key (the path of the entry). work must look in the cache before it does anything, so requests that waited for the same key answer from what the first one stored instead of doing it again. A request that only reads the cache does not come here and never waits for a slot.

The slot and the turn stay taken until work returns, also when the request that started it is gone: a blocking thread cannot be stopped, and its work is still running.

pub fn dir(&self) -> &Path

The cache directory (<vault>/previews), also of the thumbnails.

pub fn queue(&self) -> (usize, usize)

The preview queue: conversions running now and conversions waiting for a free slot (at most MAX_PARALLEL run at a time).

pub fn assembly_path(&self, sha256: &str, key: &str) -> AppResult<PathBuf>

Where the composed preview of an assembly is cached: next to the blob’s own preview, named by the components it was built from (key, hex), so a changed component gives a new file.

pub async fn mass_geometry( &self, vault: &Vault, sha256: &str, format: PreviewFormat, ) -> AppResult<Geometry>

The mass properties of a blob per unit density in model units (see massprops): from the cache, or computed from the cached preview mesh in the isolated preview process (converting the file first if needed). Failures are cached like failed previews.

pub async fn has_mesh(&self, sha256: &str) -> bool

Whether the preview mesh of a blob is already cached.

pub async fn is_converted(&self, sha256: &str) -> bool

Whether the conversion of a blob is behind us: its preview mesh or the reason why there is none is cached.

pub async fn signature( &self, vault: &Vault, sha256: &str, format: PreviewFormat, ) -> AppResult<Signature>

The shape signature of a blob (see shape): from the cache, written by the conversion, or computed from the cached preview mesh in the isolated preview process. Failures are cached like failed previews.

pub async fn mesh( &self, vault: &Vault, sha256: &str, format: PreviewFormat, ) -> AppResult<PathBuf>

The cached mesh of a blob, converting it first if necessary.

pub fn warm( self: &Arc<Self>, vault: &Vault, sha256: &str, format: PreviewFormat, )

Starts the conversion in the background (after an upload), so the first viewer does not have to wait.