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ldm0
92bdee88a4
Store immutable resource extents in one anonymous temporary file using positioned I/O. Reuse exact or worst-fit holes through offset and size indexes, coalesce released extents, and preserve bounded-capacity and failure behavior. Include allocator regression tests, concise documentation, and runnable examples.
30 lines
1.1 KiB
Rust
30 lines
1.1 KiB
Rust
//! Retain bytes when capacity is exhausted and cancel an unwritten reservation.
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//!
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//! Run with `cargo run -p moli-disk-pool --example capacity`.
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use moli_disk_pool::DiskPool;
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fn main() -> std::io::Result<()> {
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let pool = DiskPool::new(Some(8))?;
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let pending = pool
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.try_reserve_chunk(8)
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.expect("reserve the entire capacity");
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let bytes = b"payload".to_vec();
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let stored = pool.store(&bytes)?;
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assert!(stored.is_none());
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assert!(pool.may_write()); // Capacity exhaustion does not disable allocation.
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assert_eq!(bytes, b"payload"); // The caller still owns its fallback bytes.
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drop(pending); // No file write was needed to release this reservation.
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let stored = pool.store(&bytes)?.expect("the released range now fits");
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assert_eq!(stored.to_vec()?, bytes);
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assert_eq!(pool.diagnostics().disk_footprint_bytes, 8);
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println!(
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"Stored {} bytes after cancelling the reservation; logical high-water mark: {} bytes.",
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bytes.len(),
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pool.diagnostics().disk_footprint_bytes,
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);
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Ok(())
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}
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