coder2z commented on code in PR #12261:
URL: https://github.com/apache/apisix/pull/12261#discussion_r2533018058
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apisix/balancer/least_conn.lua:
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@@ -17,33 +17,146 @@
local core = require("apisix.core")
local binaryHeap = require("binaryheap")
+local dkjson = require("dkjson")
local ipairs = ipairs
local pairs = pairs
-
+local ngx = ngx
+local ngx_shared = ngx.shared
+local tostring = tostring
local _M = {}
+-- Shared dictionary to store connection counts across balancer recreations
+local CONN_COUNT_DICT_NAME = "balancer-least-conn"
+local conn_count_dict
local function least_score(a, b)
return a.score < b.score
end
+-- Get the connection count key for a specific upstream and server
+local function get_conn_count_key(upstream, server)
+ local upstream_id = upstream.id
+ if not upstream_id then
+ -- Fallback to a hash of the upstream configuration using stable
encoding
+ upstream_id = ngx.crc32_short(dkjson.encode(upstream))
+ core.log.debug("generated upstream_id from hash: ", upstream_id)
+ end
+ local key = "conn_count:" .. tostring(upstream_id) .. ":" .. server
+ core.log.debug("generated connection count key: ", key)
+ return key
+end
+
+-- Get the current connection count for a server from shared dict
+local function get_server_conn_count(upstream, server)
+ local key = get_conn_count_key(upstream, server)
+ local count, err = conn_count_dict:get(key)
+ if err then
+ core.log.error("failed to get connection count for ", server, ": ",
err)
+ return 0
+ end
+ local result = count or 0
+ core.log.debug("retrieved connection count for server ", server, ": ",
result)
+ return result
+end
+
+-- Increment the connection count for a server
+local function incr_server_conn_count(upstream, server, delta)
+ local key = get_conn_count_key(upstream, server)
+ local new_count, err = conn_count_dict:incr(key, delta or 1, 0)
+ if not new_count then
+ core.log.error("failed to increment connection count for ", server, ":
", err)
+ return 0
+ end
+ core.log.debug("incremented connection count for server ", server, " by ",
delta or 1,
+ ", new count: ", new_count)
+ return new_count
+end
+
+-- Clean up connection counts for servers that are no longer in the upstream
+local function cleanup_stale_conn_counts(upstream, current_servers)
+ local upstream_id = upstream.id
+ if not upstream_id then
+ upstream_id = ngx.crc32_short(dkjson.encode(upstream))
+ end
+
+ local prefix = "conn_count:" .. tostring(upstream_id) .. ":"
+ core.log.debug("cleaning up stale connection counts with prefix: ", prefix)
+ local keys, err = conn_count_dict:get_keys(0) -- Get all keys
+ if err then
+ core.log.error("failed to get keys from shared dict: ", err)
+ return
+ end
+
+ for _, key in ipairs(keys or {}) do
+ if core.string.has_prefix(key, prefix) then
+ local server = key:sub(#prefix + 1)
+ if not current_servers[server] then
+ -- This server is no longer in the upstream, clean it up
+ local ok, delete_err = conn_count_dict:delete(key)
+ if not ok and delete_err then
+ core.log.error("failed to delete stale connection count
for server ",
+ server, ": ", delete_err)
+ else
+ core.log.info("cleaned up stale connection count for
server: ", server)
+ end
+ end
+ end
+ end
+end
function _M.new(up_nodes, upstream)
+ if not conn_count_dict then
+ conn_count_dict = ngx_shared[CONN_COUNT_DICT_NAME]
+ end
+
+ -- Enable persistent counting only when explicitly requested
+ -- This ensures complete backward compatibility with existing behavior
+ local use_persistent_counting = conn_count_dict ~= nil and
+ upstream.persistent_conn_counting == true
Review Comment:
If it is the standalone method, it is the simplest, directly modify the
upstream configuration item, and if it is the UI mode, you need to modify the
corresponding route and UI.
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