orderbook-rs 0.9.0

A high-performance, lock-free price level implementation for limit order books in Rust. This library provides the building blocks for creating efficient trading systems with support for multiple order types and concurrent access patterns.
Documentation 
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use std::time::{SystemTime, UNIX_EPOCH};

/// Returns the current wall-clock time in milliseconds since the UNIX epoch.
///
/// The value is the `SystemTime::now()` UNIX-epoch duration truncated to `u64`
/// milliseconds. Returns `0` if the system clock is set before the epoch
/// (1970-01-01), which should never happen on correctly-configured systems.
///
/// # Determinism
///
/// This reads the **wall clock**, so it is **non-monotonic** (it can jump
/// forward or backward on NTP steps / clock adjustments) and is **not
/// reproducible** across runs. Do **not** call it on any deterministic or
/// replay-critical path — the matching engine, sequencer, and journal must take
/// their time from the injected [`Clock`](crate::Clock) trait
/// ([`MonotonicClock`](crate::MonotonicClock) in production,
/// [`StubClock`](crate::StubClock) in tests) so replays reproduce
/// engine-assigned timestamps byte-for-byte. This helper is for logging,
/// metrics, and other non-deterministic, non-journaled uses only.
#[must_use = "the current time is returned and should be used"]
pub fn current_time_millis() -> u64 {
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .map(|d| d.as_millis() as u64)
        .unwrap_or(0)
}