Crate simulacra 

Simulacra: A deterministic discrete-event simulation engine.

Simulacra is designed for modeling message flow across large computer networks with pluggable latency, jitter, and failure models.

Core Concepts

• Time: Simulated time advances by events, not wall clock time
• Events: The atomic units of causality, ordered by time and sequence
• Determinism: Given the same seed and inputs, simulations produce identical results

Example

use simulacra::{Simulation, Time, Duration};

// Define your event type
#[derive(Debug)]
enum Event {
    Tick(u32),
}

// Create and run a simulation
let mut sim = Simulation::new();
sim.schedule(Time::from_millis(100), Event::Tick(1));
sim.schedule(Time::from_millis(200), Event::Tick(2));

let stats = sim.run(|sim, event| {
    println!("At {}: {:?}", sim.now(), event);
});

println!("Processed {} events", stats.events_processed);

Deterministic Random Numbers

use simulacra::SimRng;

let mut rng = SimRng::new(42);

// Same seed produces identical sequences
let mut rng2 = SimRng::new(42);
assert_eq!(rng.u64(100), rng2.u64(100));

Re-exports

pub use scenario::Scenario;

pub use trace::TraceLoadError;

pub use trace::ReplayError;

pub use trace::TRACE_SCHEMA_VERSION;

pub use trace::Trace;

pub use trace::TraceEvent;

pub use trace::TraceMismatch;

pub use trace::TraceRecorder;

pub use net::DropPolicy;

pub use net::DropReason;

pub use net::FixedLatency;

pub use net::LatencyModel;

pub use net::Message;

pub use net::MessageId;

pub use net::NetConfig;

pub use net::NetEvent;

pub use net::NetTraceDropReason;

pub use net::NetTraceEvent;

pub use net::Network;

pub use net::NetworkStats;

pub use net::NodeId;

pub use net::OverheadPlusJitter;

pub use net::PercentageJitter;

pub use net::Route;

pub use net::RunContext;

pub use net::SpikyLatency;

pub use net::Topology;

pub use net::TopologyBuilder;

pub use net::TracedNetwork;

pub use net::UniformJitter;

pub use task::CancellationToken;

pub use task::Either;

pub use task::Envelope;

pub use task::NodeContext;

pub use task::Recv;

pub use task::RecvTimeout;

pub use task::Select2;

pub use task::SendFut;

pub use task::Sleep;

pub use task::TaskId;

pub use task::TaskSim;

pub use task::TaskSimBuilder;

pub use task::TaskSimStats;

pub use task::select2;

Modules

net

Network simulation module.

parallel

Parallel execution of independent simulation runs.

scenario

Fluent scenario builder for the async task facade.

task

Async task facade for node-based simulations.

trace

Event tracing and replay for simulation observability.

Structs

Duration

A duration of simulated time.

EventQueue

A priority queue of scheduled events.

Scheduled

A scheduled event with deterministic ordering.

SimRng

A deterministic random number generator for simulations.

Simulation

The core simulation engine.

SimulationStats

Statistics about a completed simulation run.

Time

A point in simulated time, represented as nanoseconds from simulation start.