Minetest HTTP API QoS control queue

Usage:

Function QoS returns HTTP API wrapped within simple request priority manager. HttpAPI QoS(http_api, default_priority = 3)

Simply wrap minetest.request_http_api with QoS and you're good to go.

local http = minetest.request_http_api()

http = QoS and QoS(http, 2) or http

or alternative if you like:

local http = QoS and QoS(minetest.request_http_api(), 2) or minetest.request_http_api()

Priorities

QoS comes with 3 priority levels without interesting names, priority levels are 1, 2 and 3.

Lowest number is highest priority and priority 1 requests can cause queue to get clogged.

Priorities 2 and 3 will always leave empty space for priority 1 requests and cannot completely fill queues ever.

Queued requests will be processed in first in, first out order but in a way that queued highest priority requests will be handled first and lower priorities only if there's still free slots for parallel processing.

Extras

Minetest HTTP API

QoS provides priority_override as last argument for HTTP API functions, this can be used to override default priority.

• http.fetch(req, callback, priority_override) If no priority_override provided then one given to QoS(http_api, priority) initialization function is used.
• http.fetch_async(req, priority_override) If no priority_override provided then one given to QoS(http_api, priority) initialization function is used.

Monitoring functions:

• QoS.queue_length(priority) Return total number of queued requests by priority. If priority not given then return sum of all priorities.
• QoS.active_requests() Return total number of active executed but not yet finished requests.
• QoS.active_utilization() Return % utilization of engine request queue.
• QoS.queue_size(priority) Return % utilization of engine request queue.
• QoS.utilization(priority) Return % utilization of queue by priority. If priority not given then aggregate utilization of all queues is returned.