Daptin Files

Asset serving reliability and scalability

This release fixes the concurrent cold-cache failure reported in #262 and aligns private asset delivery with the optimized hosted-site serving path.

Fixed

• Coalesces concurrent cache misses for the same cloud object into one download, preventing requests from racing on a shared temporary path and returning false 404 responses.
• Uses uniquely owned temporary files and atomic promotion into the local cache, including safe handling when another Daptin process completes the same cache fill first.
• Returns 404 only for confirmed missing objects; transient cloud-storage and cancellation failures now return 502 or 503 and do not poison the hosted-site negative cache.
• Synchronizes rclone global configuration while constructing cloud filesystems so concurrent stores cannot observe another stores credentials.

Performance and consistency

• Bounds distinct cloud downloads to protect CPU, memory, file descriptors, and backend connections during cold-cache bursts.
• Propagates request cancellation while allowing an in-progress shared cache fill to complete for other waiters.
• Reuses the existing asset file handle during image processing.
• Adds reusable gzip sidecars for large compressible private assets.
• Uses correct gzip quality negotiation, representation-specific ETags, nanosecond-precision file ETags, and uncompressed byte-range responses.
• Preserves private cache control and authorization-aware Vary headers.
• Reduces cold-cache log amplification to one download log per shared fill.

Verification

• Added a 32-client concurrent cold-cache regression test with content-integrity and temporary-file cleanup checks.
• Added coverage for missing-object classification, gzip negotiation, representation ETags, and compressed range bypass.
• Passed the complete Go test suite and repeated race-enabled cache concurrency tests.

Full changelog: https://github.com/daptin/daptin/compare/v0.12.35...v0.12.36