lintel-schema-cache

Disk-backed schema cache with HTTP fetching and JSON parsing. Part of the Lintel project. Fetches JSON schemas over HTTP and stores results locally for fast subsequent lookups.

Features

• SHA-256 keyed caching — schemas are stored as <cache_dir>/<sha256>.json where <sha256> is the hex digest of the URI, avoiding hash collisions
• Conditional requests — uses ETag / If-None-Match headers to avoid re-downloading unchanged schemas
• TTL support — configurable time-to-live for cache entries based on file modification time
• In-memory layer — frequently accessed schemas are also kept in memory for zero-IO lookups
• jsonschema integration — implements jsonschema::AsyncRetrieve for seamless use as a schema resolver
• Test-friendly — SchemaCache::memory() constructor creates a memory-only cache with no HTTP or disk I/O

Usage

use lintel_schema_cache::SchemaCache;
use std::time::Duration;

// Uses sensible defaults: system cache dir, 12h TTL
let cache = SchemaCache::builder().build();

// Or customize:
let cache = SchemaCache::builder()
    .force_fetch(true)
    .ttl(Duration::from_secs(3600))
    .build();

let (schema, status) = cache.fetch("https://json.schemastore.org/tsconfig.json").await?;
// status: Hit (from disk/memory), Miss (fetched and cached), or Disabled (no cache dir)

Testing

Use the memory-only constructor to avoid network and disk I/O in tests:

use lintel_schema_cache::SchemaCache;

let cache = SchemaCache::memory();
cache.insert("https://example.com/schema.json", serde_json::json!({"type": "object"}));
let (val, _status) = cache.fetch("https://example.com/schema.json").await?;

License

Apache-2.0