dtourolle
d6ddd0703b
A thumbnail is the one derived artefact worth sending over the wire: it costs a range fetch plus a decode to produce and is identical for every client looking at the same file. A second device that downloads a shard gets a full grid without fetching a byte of RAW. Sharded at 25 MB, filled sequentially. The cap is about sync granularity, not SQLite's limits — one growing database means every client re-downloads it whenever a single thumbnail is added, whereas with sequential fill only the newest shard is ever dirty and sealed shards are safe to cache forever. Stored JPEG-encoded rather than as raw RGBA: a 256px RGBA buffer is ~256 KB against ~20 KB encoded, and that 13x is transfer cost on every client. Keyed on Nextcloud's oc:fileid, stable across server-side rename and move. Assisted-by: LLM
22 lines
668 B
Rust
22 lines
668 B
Rust
//! TRACES: NFR-ARCH-4
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//! Thumbnail store errors.
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//!
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//! A thumbnail is a cache entry, never authoritative — every failure here is
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//! recoverable by regenerating from the source, so nothing in this module is
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//! fatal to the app.
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/// Something went wrong reading or writing the store.
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#[derive(Debug, thiserror::Error)]
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pub enum ThumbError {
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#[error("sqlite: {0}")]
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Sqlite(#[from] rusqlite::Error),
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/// The index names a shard whose file is absent — a partial sync, or a
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/// manual deletion. The entry is treated as a miss and regenerated.
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#[error("shard {0} is missing")]
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MissingShard(u32),
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#[error("io: {0}")]
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Io(String),
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}
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