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**Table of Contents**

- [Pattern Performance Benchmark Specification](#pattern-performance-benchmark-specification)
  - [Overview](#overview)
  - [Benchmark Categories](#benchmark-categories)
    - [1. Compilation Error Fix Pattern Benchmarks](#1-compilation-error-fix-pattern-benchmarks)
    - [2. Poka-Yoke Pattern Benchmarks](#2-poka-yoke-pattern-benchmarks)
    - [3. Lean Test Refactoring Benchmarks](#3-lean-test-refactoring-benchmarks)
    - [4. Gemba Walk Scoring Benchmarks](#4-gemba-walk-scoring-benchmarks)
    - [5. FMEA Calculation Benchmarks](#5-fmea-calculation-benchmarks)
  - [Memory Profiling](#memory-profiling)
    - [Allocation Tracking](#allocation-tracking)
    - [Zero-Copy Verification](#zero-copy-verification)
    - [Memory Leak Detection](#memory-leak-detection)
    - [Builder Pattern Overhead](#builder-pattern-overhead)
  - [Regression Detection](#regression-detection)
    - [Baseline Establishment](#baseline-establishment)
    - [Continuous Monitoring](#continuous-monitoring)
    - [Automated Assertions](#automated-assertions)
    - [Performance Targets](#performance-targets)
  - [Statistical Analysis](#statistical-analysis)
    - [Criterion Features](#criterion-features)
    - [Multi-threaded Execution](#multi-threaded-execution)
  - [Report Generation](#report-generation)
    - [Criterion HTML Reports](#criterion-html-reports)
    - [Custom Summary Reports](#custom-summary-reports)
    - [Validation Reports](#validation-reports)
  - [Continuous Integration](#continuous-integration)
    - [GitHub Actions Integration](#github-actions-integration)
    - [Performance Regression Alerts](#performance-regression-alerts)
  - [Benchmark Maintenance](#benchmark-maintenance)
    - [Adding New Patterns](#adding-new-patterns)
    - [Updating Targets](#updating-targets)
    - [Benchmark Categories](#benchmark-categories-1)
  - [Performance Analysis Workflow](#performance-analysis-workflow)
  - [Expected Results](#expected-results)
    - [All Targets Met](#all-targets-met)
    - [Performance Characteristics](#performance-characteristics)
    - [Memory Profile](#memory-profile)
  - [References](#references)

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# Pattern Performance Benchmark Specification

## Overview

Comprehensive performance benchmarking suite for all TDD patterns documented in the codebase. Uses Criterion for statistical analysis, memory profiling, and regression detection.

## Benchmark Categories

### 1. Compilation Error Fix Pattern Benchmarks

**Target**: <50ms latency for all error fix patterns

| Pattern | Error Code | Target Latency | Complexity |
|---------|------------|----------------|------------|
| Trait Bound Fix | E0277 | <50ms | O(1) |
| Type Mismatch Fix | E0308 | <50ms | O(1) |
| Type Annotation Fix | E0283 | <50ms | O(1) |
| Method Not Found Fix | E0599 | <50ms | O(1) |
| Batch Error Fixing | All | Linear | O(n) |

**Measurements**:
- Individual error fix latency
- Batch processing throughput
- Time complexity verification

### 2. Poka-Yoke Pattern Benchmarks

**Objective**: Verify compile-time safety has minimal runtime cost

| Pattern | Target | Expected Cost |
|---------|--------|---------------|
| Type-Safe Builder | <1μs per field | Construction time |
| Phantom Type Validation | Zero runtime | Compile-time only |
| Trait Bound Resolution | <1μs | Method dispatch |
| Const Validation | Zero runtime | Compile-time only |
| Zero-Copy Overhead | <1% | Allocation delta |

**Measurements**:
- Builder construction time per field
- Phantom type state transition overhead
- Trait method resolution time
- Memory allocation comparison

### 3. Lean Test Refactoring Benchmarks

**Objective**: Ensure test infrastructure is lightweight

| Component | Target | Purpose |
|-----------|--------|---------|
| TestFixtureBuilder | <5ms | Fixture creation |
| Setup | <10ms | Test preparation |
| Teardown | <10ms | Cleanup |
| State Isolation | Zero leaks | Memory verification |
| Test Execution | <100ms | Per test |

**Measurements**:
- Fixture creation time
- Setup/teardown overhead
- State isolation verification
- Memory leak detection

### 4. Gemba Walk Scoring Benchmarks

**Objective**: Fast quality assessment

| Operation | Target | Scale |
|-----------|--------|-------|
| Score Calculation | <1ms | Per test |
| Observability Tracking | <5% overhead | Runtime cost |
| Quality Report | <100ms | 100 tests |
| Pattern Recognition | <10ms | Per pattern |

**Measurements**:
- Individual test scoring time
- Observability overhead percentage
- Report generation for varying test counts
- Pattern analysis performance

### 5. FMEA Calculation Benchmarks

**Objective**: Real-time risk assessment

| Calculation | Target | Data Size |
|-------------|--------|-----------|
| RPN Calculation | <1μs | Per error |
| Distribution Analysis | <100μs | 252 errors |
| Priority Ranking | <1ms | All errors |
| Risk Categorization | <500μs | All categories |

**Measurements**:
- Individual RPN calculation time
- Batch distribution analysis
- Priority sorting performance
- Category assignment time

## Memory Profiling

### Allocation Tracking

**Tools**: Custom `TrackingAllocator` wrapping `System`

**Metrics**:
- Total bytes allocated
- Total bytes deallocated
- Allocation count
- Leaked bytes (target: <100 bytes)

### Zero-Copy Verification

**Patterns to verify**:
1. Slice operations (no allocation)
2. Reference passing (no cloning)
3. Borrow semantics (no ownership transfer)

**Target**: Zero allocations for zero-copy patterns

### Memory Leak Detection

**Method**: Run operations 1000x and verify:
```rust
leaked_bytes = allocated - deallocated
assert!(leaked_bytes < 100);
```

### Builder Pattern Overhead

**Comparison**:
- Builder construction vs direct initialization
- Target: <1% allocation increase

## Regression Detection

### Baseline Establishment

Criterion saves baselines for comparison:
```bash
cargo bench -- --save-baseline pattern_baseline
```

### Continuous Monitoring

Each benchmark run compares against baseline:
```bash
cargo bench -- --baseline pattern_baseline
```

### Automated Assertions

Benchmarks include assertions that fail if targets are exceeded:
```rust
assert!(avg_latency <= target,
    "Exceeded target: {:?} > {:?}", avg_latency, target);
```

### Performance Targets

All targets are encoded as constants:
```rust
const ERROR_FIX_LATENCY_TARGET_MS: u128 = 50;
const BUILDER_CONSTRUCTION_TARGET_US: u128 = 1;
const FIXTURE_CREATION_TARGET_MS: u128 = 5;
// ... etc
```

## Statistical Analysis

### Criterion Features

**Enabled**:
- Statistical outlier detection
- Regression analysis
- HTML report generation
- Comparison against baselines
- Throughput measurements

**Configuration**:
```rust
group.measurement_time(Duration::from_secs(10));
group.sample_size(1000);
```

### Multi-threaded Execution

**Criterion parallel benchmarking**:
```bash
cargo bench -- --parallel
```

**Thread-safe measurements**:
- Atomic counters for memory tracking
- SeqCst ordering for accuracy
- Isolated benchmark groups

## Report Generation

### Criterion HTML Reports

**Location**: `target/criterion/index.html`

**Contents**:
- Performance distribution charts
- Regression analysis graphs
- Statistical summaries
- Comparison views

### Custom Summary Reports

**Script**: `scripts/run_pattern_benchmarks.sh`

**Generates**:
- Markdown summary with pass/fail status
- Performance target validation
- Trend analysis
- Action items

### Validation Reports

**Script**: `scripts/validate_benchmark_targets.sh`

**Output**:
```
✓ E0277 Fix: 23.4ms (53% under target of 50ms)
✓ Builder Construction: 743ns (26% under target of 1μs)
✗ Score Calculation: 1.2ms (20% over target of 1ms)
```

## Continuous Integration

### GitHub Actions Integration

```yaml
- name: Run Pattern Benchmarks
  run: |
    cargo bench --bench pattern_performance
    cargo bench --bench memory_profiling
    cargo bench --bench regression_detection

- name: Validate Targets
  run: ./scripts/validate_benchmark_targets.sh
```

### Performance Regression Alerts

**Criterion** automatically detects:
- Significant performance changes (>5%)
- Statistical outliers
- Variance increases

**Exit codes**:
- `0` = All targets met
- `1` = Regressions detected

## Benchmark Maintenance

### Adding New Patterns

1. **Identify performance-critical code**
2. **Define target latency/overhead**
3. **Add benchmark to appropriate file**
4. **Update target constants**
5. **Run baseline establishment**
6. **Document in this specification**

### Updating Targets

When justified by optimization:
1. Run benchmarks with new code
2. Verify sustained improvement
3. Update target constants
4. Re-establish baseline
5. Document change rationale

### Benchmark Categories

| File | Purpose | Patterns |
|------|---------|----------|
| `pattern_performance.rs` | Core pattern latencies | All 5 categories |
| `memory_profiling.rs` | Allocation tracking | Zero-copy, leaks, overhead |
| `regression_detection.rs` | Target validation | All performance targets |

## Performance Analysis Workflow

1. **Run benchmarks**: `./scripts/run_pattern_benchmarks.sh`
2. **Review HTML reports**: Open `target/criterion/index.html`
3. **Validate targets**: `./scripts/validate_benchmark_targets.sh`
4. **Analyze failures**: Check specific benchmark output
5. **Investigate regressions**: Compare against baseline
6. **Optimize code**: Focus on failed targets
7. **Re-run benchmarks**: Verify improvements
8. **Update baselines**: Establish new baseline if improved

## Expected Results

### All Targets Met

```
========================================
Validation Summary
========================================

Passed: 25
Warnings: 0
Failed: 0

✓ All performance targets validated successfully!
```

### Performance Characteristics

| Metric | Expected Value | Variance |
|--------|---------------|----------|
| Error Fix Latency | 20-40ms | ±10ms |
| Builder Construction | 500-900ns | ±200ns |
| Fixture Creation | 1-3ms | ±1ms |
| Score Calculation | 200-800μs | ±200μs |
| RPN Calculation | 50-500ns | ±100ns |

### Memory Profile

| Pattern | Expected Allocations | Leaked Bytes |
|---------|---------------------|--------------|
| Zero-Copy | 0 | 0 |
| Builder | 1-2 per field | <10 |
| Fixture | 5-10 | <50 |
| Test Execution | Varies | <100 total |

## References

- **Criterion Documentation**: https://bheisler.github.io/criterion.rs/book/
- **Rust Performance Book**: https://nnethercote.github.io/perf-book/
- **Quick Wins Report**: `QUICK_WINS_PERFORMANCE_REPORT.md`
- **TDD Test Improvements**: `docs/TEST_IMPROVEMENTS_WEEK1.md`

---

**Maintained by**: TDD Performance Benchmarking Team
**Last Updated**: 2025-11-19
**Version**: 1.0.0
