using Mostlylucid.Ephemeral.Patterns.PersistentWindow;
await using var window = new PersistentSignalWindow(
"Data Source=signals.db",
flushInterval: TimeSpan.FromSeconds(30));
// On startup: restore previous signals
await window.LoadFromDiskAsync(maxAge: TimeSpan.FromHours(24));
// Raise signals as normal
window.Raise("order.completed", key: "order-service");
window.Raise("payment.processed", key: "payment-service");
// Query signals
var recentOrders = window.Sense("order.*");
// Signals automatically flush every 30 seconds
// Also flushes on dispose
All Options
new PersistentSignalWindow(
// Required: SQLite connection string
connectionString: "Data Source=signals.db",
// How often to flush to disk
// Default: 30 seconds
flushInterval: TimeSpan.FromSeconds(30),
// Max signals to persist per flush
// Default: 1000
maxSignalsPerFlush: 1000,
// Max signals in memory window
// Default: 10000
maxWindowSize: 10000,
// Max age of signals in memory
// Default: 10 minutes
windowMaxAge: TimeSpan.FromMinutes(10),
// Signal sampling rate for diagnostics
// Default: 10 (1 in 10)
sampleRate: 10
)
┌─────────────────────────────────────┐
Raise() ───────>│ In-Memory SignalSink (fast) │
│ - maxWindowSize: 10000 │
│ - windowMaxAge: 10 minutes │
└─────────────┬───────────────────────┘
│
│ Every 30 seconds (flushInterval)
▼
┌─────────────────────────────────────┐
│ SQLite (durable) │
│ - Single-writer coordination │
│ - WAL mode for performance │
│ - Indexed by timestamp & signal │
└─────────────────────────────────────┘
│
│ On startup: LoadFromDiskAsync()
▼
┌─────────────────────────────────────┐
│ Restored signals back to memory │
└─────────────────────────────────────┘
Signals Emitted
Signal
Description
window.initialized
SQLite schema created
window.raise
Signal raised (sampled)
window.flush.start:{count}
Starting flush
window.flush.done:{count}
Flush completed
window.flush.error
Flush failed
window.load.done:{count}
Signals loaded from disk
Example: Error Monitoring with Persistence
await using var window = new PersistentSignalWindow(
"Data Source=errors.db",
flushInterval: TimeSpan.FromSeconds(10),
maxWindowSize: 50000);
// On startup: restore last 24 hours of errors
await window.LoadFromDiskAsync(maxAge: TimeSpan.FromHours(24));
// In your error handler
try
{
await ProcessRequest();
}
catch (Exception ex)
{
window.Raise($"error:{ex.GetType().Name}", key: Environment.MachineName);
}
// Dashboard query
var last5Minutes = window.Sense(s =>
s.Signal.StartsWith("error:") &&
s.Timestamp > DateTimeOffset.UtcNow.AddMinutes(-5));
Console.WriteLine($"Errors in last 5 min: {last5Minutes.Count}");
Example: Distributed Event Tracking
// Each service instance has its own window
await using var window = new PersistentSignalWindow(
$"Data Source=events_{Environment.MachineName}.db",
windowMaxAge: TimeSpan.FromHours(1));
// Restore on startup
await window.LoadFromDiskAsync(maxAge: TimeSpan.FromHours(1));
// Track events
window.Raise("user.login", key: userId);
window.Raise("order.placed", key: orderId);
// Query for patterns
var userActivity = window.Sense("user.*");
var orderEvents = window.Sense("order.*");
Example: Graceful Shutdown
var window = new PersistentSignalWindow("Data Source=app.db");
// Handle shutdown signal
Console.CancelKeyPress += async (s, e) =>
{
e.Cancel = true;
Console.WriteLine("Flushing signals...");
await window.FlushAsync();
await window.DisposeAsync();
Environment.Exit(0);
};
// Or in ASP.NET Core
public class SignalWindowService : IHostedService
{
private readonly PersistentSignalWindow _window;
public async Task StartAsync(CancellationToken ct)
{
await _window.LoadFromDiskAsync(TimeSpan.FromHours(24), ct);
}
public async Task StopAsync(CancellationToken ct)
{
await _window.FlushAsync(ct);
await _window.DisposeAsync();
}
}
Database Schema
The window creates these tables automatically:
CREATE TABLE signals (
id INTEGER PRIMARY KEY,
operation_id INTEGER NOT NULL,
signal TEXT NOT NULL,
key TEXT,
timestamp TEXT NOT NULL,
created_at TEXT DEFAULT CURRENT_TIMESTAMP
);
CREATE INDEX idx_signals_timestamp ON signals(timestamp);
CREATE INDEX idx_signals_signal ON signals(signal);
