Rate Limits

In Trypema, a rate limit is a per-second value stored in RateLimit.

Fractional rates are normal

You are not limited to whole numbers:

• 10.0 means ten requests per second
• 5.5 means five and a half requests per second
• 0.5 means roughly one request every two seconds

Window capacity

Trypema enforces rates over a sliding window, so the rough budget for a key is:

window capacity = rate_limit_per_second × window_size_seconds

Example:

• rate limit = 5.0
• window = 60s
• capacity = about 300 requests in the current moving window

Sticky per key

The first inc(...) call for a key stores that key's rate limit. Later calls for the same key keep using the stored value instead of replacing it mid-window.

This prevents inconsistent behavior when multiple parts of an application accidentally pass different limits for the same key.

How to think about it

• Use low fractional values for sparse events.
• Use whole-number rates for common request budgets.
• Treat the first rate applied to a key as the rate that key will carry while it remains active.