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Simulation Command

The arc sim command allows you to simulate the potential impact of code changes before merging them. It analyzes your changes, runs tests in a sandbox environment, and provides insights into how they might affect your system.

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Usage

arc sim <subcommand> [options]

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Subcommands

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run

Run a simulation on the current changes. 
arc sim run [options]

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history

Show the history of previous simulations. 
arc sim history [options]

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show

Show details of a specific simulation. 
arc sim show <simulation_id>

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Options for run

OptionDescription
--scenario <scenario>Simulation scenario to run (default: all)
--diff <diff_path>Path to a diff file to simulate (default: current changes)
--branch <branch>Branch to compare against (default: main)
--sandbox <type>Sandbox type: local, docker, e2b (default: local)
--memoryUse memory from previous simulations to improve results
--output <format>Output format: text, json, markdown (default: text)
--save <path>Save simulation results to a file
--debugEnable debug mode

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Options for history

OptionDescription
--limit <n>Limit the number of results (default: 10)
--format <format>Output format: text, json, table (default: table)
--service <service>Filter by affected service
--scenario <scenario>Filter by scenario
--risk <min>..<max>Filter by risk score range

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Simulation Scenarios

Arc Memory supports the following simulation scenarios:
ScenarioDescription
network_latencySimulates the impact on network latency
memory_usageSimulates the impact on memory usage
cpu_usageSimulates the impact on CPU usage
disk_ioSimulates the impact on disk I/O
error_ratesSimulates the impact on error rates
securityAnalyzes potential security implications
dependenciesAnalyzes impact on dependencies
allRuns all available scenarios

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Examples

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Basic Simulation

arc sim run
This will run a simulation on your current changes against the main branch.

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Specific Scenario

arc sim run --scenario network_latency
This will run only the network latency simulation.

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Using a Different Branch

arc sim run --branch develop
This will compare your changes against the develop branch.

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Using Memory

arc sim run --memory
This will use insights from previous simulations to improve the results.

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Viewing Simulation History

arc sim history
This will show a table of your recent simulations.

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Filtering History

arc sim history --service auth-service --scenario network_latency
This will show only simulations that affected the auth-service and ran the network_latency scenario.

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Viewing Specific Simulation

arc sim show sim_abc123
This will show detailed results for the simulation with ID sim_abc123.

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Output Format

The simulation results include:
  1. Summary: An overview of the simulation, including risk score and affected services
  2. Detailed Analysis: In-depth analysis of potential impacts
  3. Metrics: Quantitative metrics showing predicted changes
  4. Recommendations: Suggestions for mitigating potential issues
Example output: 
Simulation Results: sim_abc123
Date: 2023-05-15 14:30:45

Summary:
- Risk Score: 35/100 (Moderate)
- Affected Services: auth-service, api-gateway
- Scenarios: network_latency, memory_usage

Detailed Analysis:
The changes to the authentication middleware could increase latency by
approximately 15-20ms for authentication requests. This is primarily due
to the additional validation step added in auth_middleware.py.

Memory usage is expected to increase by about 5MB per instance due to
caching of validation results.

Metrics:
- Network Latency: +15-20ms for auth requests
- Memory Usage: +5MB per instance
- CPU Usage: No significant change
- Error Rates: No significant change

Recommendations:
1. Consider implementing a more efficient validation algorithm
2. Add monitoring for auth request latency after deployment
3. Verify memory usage in staging environment before production deployment

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Sandbox Environments

Arc Memory supports different sandbox environments for running simulations:
EnvironmentDescription
localRuns in a local sandbox with limited isolation
dockerRuns in a Docker container for better isolation
e2bRuns in an E2B cloud sandbox for maximum isolation and reproducibility

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Troubleshooting

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Simulation Fails to Start

If the simulation fails to start:
  1. Check if you have the necessary permissions
  2. Verify that the sandbox environment is properly configured
  3. Check if there are any syntax errors in your changes
  4. Run with --debug for more detailed error information

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Inaccurate Results

If you believe the simulation results are inaccurate:
  1. Try running with a different sandbox environment
  2. Ensure your local environment has all dependencies installed
  3. Run with --memory to leverage insights from previous simulations
  4. Check if the test coverage is sufficient for your changes

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See Also