Flags: declared, read and tested

Each flag in flags { } is a Bool or an enum whose variants carry no data, with a default: written as a test's flags: writes a value, an owner: in quotes, and an expires: date in quotes, "2027-01-31". A flag missing one of the three, giving one that isn't valid, of another type, or declared twice is flag.declaration_invalid. client: true or false says whether GET /flags answers it (GET /flags).

Where it is read

An action, a test and a route's run: arguments read flags.<name>; a test's read gives what its flags: says. A function, a constant, a rule or a template reading one is flag.read_context, and a name no flag has is flag.unknown, in code and in a test's flags:, with the nearest flag's name offered.

The state each server holds

jadpo_flags holds a row for each flag that has been changed: everyone's value, NULL for the default:; the named users' values, an object of each user's id to a value; and the shares of users, an array of [value, percent] pairs in order, each a whole percentage. A value is true or false, or a variant's name. A flag with no row, and a value no variant has any more, give the default:.

Each server reads the table at most every five seconds, as a request or a tick begins, so a change applies within ten seconds. A read that fails keeps what the server had, or nothing, which gives every flag its default:, and the next is tried five seconds later. The first flag an operation reads fixes the state for the rest of it, and each flag's value is worked out once per operation.

Who is in a share

A user's place among 100 is the first eight bytes of the BLAKE3 hash of the flag's name, a zero byte and the user's id in lowercase, read as a little-endian number, modulo 100. A user whose place is below the first share's percentage gets its value, below the first two shares' sum the second's, and so on; anyone else gets everyone's value. A named user's value comes before any share. A service, a schedule's run, a subscriber's delivery and a request no one signed in to have no user, so they get everyone's value.

Judging a flag's date

jadpo check judges expires: at today and jadpo build at the commit's date, both in UTC, or at SOURCE_DATE_EPOCH when it is set. A flag is past its date from the day after it, and flag.expired names its owner. Running a program or its tests judges no date.