Stock exchange (order matching engine)

Accept limit and market orders, enforce pre-trade risk limits, and match buys against sells by strict price-time priority. Traditional database locks are orders of magnitude too slow and non-deterministic; a real exchange sequences commands into a total order per symbol and runs a single-threaded, in-memory deterministic state machine.

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Duration 45:00

Requirements checklist

Place new limit and market orders (`BUY` / `SELL`, `symbol`, `priceTicks`, `quantity`, `clientOrderId`) and cancel open orders.Match orders strictly by price-time priority (best price first; ties broken FIFO by sequencer timestamp/sequence).Publish execution reports to the trading parties and stream L1/L2 market data (top-of-book and depth) to subscribers.Deterministic total ordering per symbol: replaying the input command log must produce the exact same trades and order book state.Sub-millisecond to single-digit-millisecond matching latency; hundreds of thousands of orders/s across symbols.Zero lost or reordered executions, and zero duplicate orders when a gateway retries.

Clarifying questions

Which order types are in scope (limit, market, cancel, IOC/FOK)?
What is the latency target at the matching engine (sub-millisecond vs tens of milliseconds) and peak message rate?
How many symbols are traded, and can one hot symbol receive a large fraction of the volume?
Are pre-trade risk checks (buying power, fat-finger limits) part of the gateway path?

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requirements

Suggested time: about 6 minutes. Includes pre-trade risk checks, `clientOrderId` idempotency, and deterministic replay.

Notes for requirements