Rule Metrics

Track per-rule execution statistics for monitoring, debugging, and performance optimization.

Overview

Every Rule exposes a Metrics property that accumulates statistics atomically during execution:

Metric	Description
`EvalCount`	Total number of evaluations
`FailureCount`	Number of failed evaluations
`AverageExecutionTimeMs`	Mean execution time
`FailureRatePercent`	Failure percentage (0–100)
`LastExecuted`	UTC timestamp of last run

Quick Start

var rule = new Rule
{
    Description = "Adult check",
    Expression = "customer.Age >= 18",
    IsActive = true
};

var parameters = new[] { new RuleParameter("customer", typeof(Customer), customer) };
rule.Compile(new ExpressionCompiler(), parameters);

// Execute multiple times
rule.Execute(parameters);
rule.Execute(parameters);
rule.Execute(parameters);

// Check metrics
Console.WriteLine($"Evaluated: {rule.Metrics.EvalCount} times");
Console.WriteLine($"Avg time: {rule.Metrics.AverageExecutionTimeMs:F2} ms");
Console.WriteLine($"Failure rate: {rule.Metrics.FailureRatePercent:F1}%");
Console.WriteLine($"Last run: {rule.Metrics.LastExecuted}");

Thread Safety

Metrics update via lock-free Interlocked operations. Safe for concurrent execution:

Parallel.For(0, 1000, _ => rule.Execute(parameters));

Console.WriteLine(rule.Metrics.EvalCount); // 1000

Failure Detection

A “failure” is either:

Expression evaluates to false
Exception thrown during execution

var badRule = new Rule { Expression = "x > 0" };
badRule.Compile(compiler, new[] { new RuleParameter("x", typeof(int), -1) });

badRule.Execute(parameters); // fails: -1 > 0 is false
Console.WriteLine(badRule.Metrics.FailureRatePercent); // 100

Reset

ClearCache() also resets metrics:

rule.ClearCache();
Console.WriteLine(rule.Metrics.EvalCount); // 0

Rule — Metrics property
Result Caching — Cache and metrics interaction
Performance Tuning — Optimize based on metrics

Dashboard Integration

Export metrics for monitoring:

var report = workflow.Rules.Select(r => new
{
    r.Description,
    r.Metrics.EvalCount,
    r.Metrics.AverageExecutionTimeMs,
    r.Metrics.FailureRatePercent
});

foreach (var item in report)
{
    Console.WriteLine(
        $"{item.Description}: {item.EvalCount} evals, " +
        $"{item.AverageExecutionTimeMs:F2}ms avg, " +
        $"{item.FailureRatePercent:F1}% fail");
}