HLD-128·Caching & Edge
Easy · 500 ptsReal-Time Phishing & Safe-Browsing URL Reputation API
Design a Google Safe Browsing-style URL prefix reputation service queried by browsers and email gateways before rendering external links.
Max p99
≤ 30 ms
Availability
≥ 99.5%
Budget
≤ $2,500
Functional Requirements
- FR-1GET /safebrowsing/hash/{url_prefix} — Returns matching threat hash suffixes for a 4-byte SHA256 prefix.
- FR-2POST /safebrowsing/threats — Ingests newly detected phishing/malware domain feeds.
- FR-3PATCH & DELETE /safebrowsing/hash/{url_prefix} — Updates, revokes, or deletes url_prefix entries with bounded TTL or explicit cache/index invalidation.
- FR-4Browser navigation checks must stay under 30ms p99 even during 5x storage latency spikes.
Workload Profile
Baseline Browser Checks26,000 Read RPS / 700 Threat Feed Write RPS
Phishing Wave Surge72,000 Read RPS / 2,000 Write RPS
Active Working Set12 GB compact SHA256 prefix tables
Traffic DistributionHigh hit rate on popular domain url_prefix buckets
Consistency Model
Eventual threat-list edge sync (< 10s) acceptable; threat feed writes durably stored.
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