🚀 Optimize CI Caching and Parallel Execution

[kengggg]

🚀 Optimize CI Caching and Parallel Execution

Overview

Optimize the CI pipeline for faster feedback with improved caching strategies, parallel job execution, and workflow efficiency to achieve sub-5-minute CI completion times.

Tasks

1. Advanced Cargo Caching

• Multi-layer caching strategy - Dependencies, incremental builds, tools
• Cache key optimization - More granular cache invalidation
• Cross-job cache sharing - Shared cache between check/build jobs
• Cache size optimization - Prevent cache bloat

2. Parallel Job Optimization

• Job dependency analysis - Minimize sequential dependencies
• Matrix job optimization - Smart platform distribution
• Selective job execution - Skip unnecessary jobs on docs-only changes
• Fast-fail strategies - Early termination on critical failures

3. Workflow Efficiency

• Conditional step execution - Skip steps based on changes
• Tool installation optimization - Pre-installed runners where possible
• Output optimization - Reduce verbose logging
• Resource allocation - Optimal runner sizing

4. Incremental Build Optimization

• Target-specific building - Only build what changed
• Artifact reuse - Share build artifacts between jobs
• Compiler cache optimization - sccache integration
• Link-time optimization tuning - Balance speed vs optimization

Acceptance Criteria

• CI feedback time under 5 minutes for typical changes
• Cache hit rate above 80% for dependency builds
• Parallel jobs execute efficiently without resource contention
• Failed builds provide fast feedback (under 2 minutes)
• Documentation-only changes skip heavy jobs

Implementation Details

Enhanced Caching Strategy

- name: Setup Rust Cache
  uses: Swatinem/rust-cache@v2
  with:
    # Cache by Cargo.lock hash and target
    key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}-${{ matrix.target }}
    # Separate cache for tools
    cache-directories: |
      ~/.cargo/bin
      ~/.cargo/.crates.toml
      ~/.cargo/.crates2.json
    # Clean old cache entries
    cache-clean: true

Optimized Job Structure

strategy:
  matrix:
    include:
      # Fast checks first
      - os: ubuntu-latest
        target: x86_64-unknown-linux-gnu
        rust-version: stable
        job-type: fast-check
      
      # Platform builds in parallel  
      - os: ubuntu-latest
        target: x86_64-unknown-linux-gnu
        job-type: build
      - os: macos-latest
        target: x86_64-apple-darwin
        job-type: build
      - os: windows-latest
        target: x86_64-pc-windows-msvc
        job-type: build
  
  # Don't cancel other jobs on failure for comprehensive testing
  fail-fast: false

Conditional Execution

- name: Check if code changed
  id: changes
  uses: dorny/paths-filter@v2
  with:
    filters: |
      rust:
        - 'src/**'
        - 'tests/**'
        - 'Cargo.toml'
        - 'Cargo.lock'
      docs:
        - '*.md'
        - 'docs/**'

- name: Run tests
  if: steps.changes.outputs.rust == 'true'
  run: cargo test

Fast-Fail Implementation

jobs:
  quick-check:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
      
      - name: Quick syntax check
        run: cargo check --workspace
      
      - name: Quick test compilation
        run: cargo test --no-run
  
  full-tests:
    needs: quick-check
    # Only run if quick check passes

Optimization Targets

1. Cache Optimization

• Current: Basic Rust cache
• Target: Multi-layer caching with 80%+ hit rate
• Expected speedup: 2-3x for dependency builds

2. Job Parallelization

• Current: Sequential check → build jobs
• Target: Parallel execution where possible
• Expected speedup: 40-50% reduction in total time

3. Selective Execution

• Current: All jobs run on every change
• Target: Smart job skipping based on changes
• Expected speedup: 60-80% for docs/config changes

4. Tool Optimization

• Current: Install tools on every run
• Target: Cache tools, use pre-installed where possible
• Expected speedup: 30-60 seconds saved per job

Monitoring and Metrics

- name: Report CI timing
  run: |
    echo "Job started at: ${{ steps.start-time.outputs.time }}"
    echo "Job duration: $(($(date +%s) - ${{ steps.start-time.outputs.timestamp }}))"
    echo "Cache status: ${{ steps.cache.outputs.cache-hit }}"

Implementation Phases

Phase A: Quick Wins (Day 1)

• Enhanced Rust caching configuration
• Conditional job execution for docs changes
• Tool installation optimization

Phase B: Parallelization (Day 2)

• Job dependency restructuring
• Matrix optimization
• Fast-fail implementation

Phase C: Advanced (Day 3)

• Incremental build optimization
• Artifact sharing between jobs
• Performance monitoring integration

Testing

• Measure CI times before/after changes
• Test cache hit rates across different change types
• Verify all optimizations maintain test coverage
• Confirm parallel jobs don't have resource conflicts

Timeline

Estimate: 2-3 days
Priority: Medium
Phase: 1

Labels

enhancement, ci/cd, phase-1, priority-medium, performance

Dependencies

• Can start immediately
• Should coordinate with other Phase 1 tasks to avoid conflicts

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Part of Phase 1: Enhanced CI Foundation - Critical for developer productivity and fast feedback loops