State Management

The Decision

Best will use in-memory shell variables for state management.

The Context

Best will maintain state between function calls to allow for a simple API which follows "normal" bash syntax. This means we need some state management mechanism.

it "should _____"; expect _____; to_be _____

it "should not_____"; expect _____; not; to_be _____

it "should_____"; {
    do_something
    do_something_else
    expect _____
    to_be _____
}

Trade-offs

• Speed: declaring and updating shell variables should be faster than file system i/o
• Memory: managing only a few shell variables should limit memory usage
• Security: namespacing shell variables should avoid collisions with environment variables
• Availability: exported shell variables are available in subshells
• Dependencies: exporting shell variables requires no runtime dependencies

Alternatives Considered

• Piping values from one function to the next
• Temporary files
• Named pipes (FIFOs)
• Key/Value store (Redis)
• Database (SQLite)

The Consequences

Using in-memory shell variables for state management should come with these benefits:

• High performance
• Low memory usage
• Reasonable security
• High availability
• No runtime dependencies

Reevaluate the decision if these benefits are not realized or other downsides are discovered.