Shared remote cache upload worker for spider and chromey.

This crate provides a high-performance, concurrent batch upload worker for sending cached HTTP responses to a remote hybrid_cache_server.

Client injection

Call [set_client] at startup, before the first upload or read, to share your application's reqwest::Client. This avoids compiling a second TLS stack and reuses the existing connection pool. If nothing is injected before first use, the crate builds a default client ([default_client_builder]: 250 ms connect timeout, request timeout equal to the batch timeout) and a later [set_client] is ignored. [client_source] reports which one is active.

Site keys

Every upload carries the job's cache_site as the x-cache-site header and as the payload's website_key. A batch request only ever holds jobs with the same cache_site.

Features

• Batch-drain: Collects pending jobs from the channel before uploading
• Concurrent uploads: Configurable parallelism via semaphore (default 8)
• Lock-free dedup: DashSet for in-flight key tracking (no Mutex, no deadlocks)
• Rate limiting: Per-spawn pacing without blocking the drain loop
• Batch POST: Uses /cache/index/batch when multiple jobs are ready
• Best-effort: try_enqueue never blocks; drops on full queue
• Metrics: with the default metrics feature, counters, a gauge and a histogram go through the metrics facade (see [metrics])