HLD-413·Payments & Ledger
Expert · 2,000 ptsHigh-Frequency Crypto Margin Engine & Hot-Wallet Settlement
Design Coinbase / Binance’s 24/7 perpetuals margin collateral engine and withdrawal hot-wallet ledger preventing race-condition double-withdrawals during flash crashes.
Max p99
≤ 95 ms
Availability
≥ 99.5%
Budget
≤ $11,500
Functional Requirements
- FR-1POST /margin/{account_id}/withdraw — Atomically verifies free margin collateral, locks nonce, and debits ledger.
- FR-2GET /margin/{account_id}/equity — Returns real-time mark-to-market collateral and liquidation buffer.
- FR-3POST /margin/{account_id}/withdraw/reverse — Supports idempotent reversal/refund or campaign pause updates while keeping cached balances and deduplication keys consistent.
- FR-4Zero negative-equity race withdrawals and RPO = 0 across primary ledger node crashes.
Workload Profile
24/7 Baseline Trading64,000 Equity Read RPS / 12,500 Margin/Ledger Write RPS
20% Flash-Crash Liquidation Cascade170,000 Read RPS / 38,000 Concurrent Write RPS
Active Working Set38 GB margin positions, nonces & hot-wallet UTXO locks
Consistency GateStrict serializable collateral check + RPO = 0 quorum ledger
Consistency Model
Strict serializable per-account margin lock + idempotent withdrawal nonce + synchronous/quorum durability.
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