membphis commented on a change in pull request #2001: URL: https://github.com/apache/apisix/pull/2001#discussion_r466972744
########## File path: apisix/balancer/ewma.lua ########## @@ -0,0 +1,240 @@ +-- +-- Licensed to the Apache Software Foundation (ASF) under one or more +-- contributor license agreements. See the NOTICE file distributed with +-- this work for additional information regarding copyright ownership. +-- The ASF licenses this file to You under the Apache License, Version 2.0 +-- (the "License"); you may not use this file except in compliance with +-- the License. You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +local resty_lock = require("resty.lock") +local core = require("apisix.core") +local ngx = ngx +local ngx_shared = ngx.shared +local ngx_now = ngx.now +local tostring = tostring +local math = math +local pairs = pairs +local next = next +local tonumber = tonumber + +local _M = {} +local DECAY_TIME = 10 -- this value is in seconds +local LOCK_KEY = ":ewma_key" +local PICK_SET_SIZE = 2 +local ewma_lock, ewma_lock_err +local shm_ewma = ngx_shared.balancer_ewma +local shm_last_touched_at= ngx_shared.balancer_ewma_last_touched_at + + +local function lock(upstream) + local _, err = ewma_lock:lock(upstream .. LOCK_KEY) + if err then + if err ~= "timeout" then + core.log.error("EWMA Balancer failed to lock:", err) + end + return false, err + end + + return true +end + + +local function unlock() + local ok, err = ewma_lock:unlock() + if not ok then + core.log.error("EWMA Balancer failed to unlock:", err) + return false, err + end + + return true +end + + +local function decay_ewma(ewma, last_touched_at, rtt, now) + local td = now - last_touched_at + td = math.max(td, 0) + local weight = math.exp(-td / DECAY_TIME) + + ewma = ewma * weight + rtt * (1.0 - weight) + return ewma +end + + +local function store_stats(upstream, ewma, now) + local success, err, forcible = shm_last_touched_at:set(upstream, now) + if not success then + core.log.error("balancer_ewma_last_touched_at:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma_last_touched_at:set valid items forcibly overwritten") + end + + success, err, forcible = shm_ewma:set(upstream, ewma) + if not success then + core.log.error("balancer_ewma:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma:set valid items forcibly overwritten") + end +end + + +local function get_or_update_ewma(upstream, rtt, update) + local lock_ok, err = nil + if update then + lock_ok, err = lock(upstream) + end + local ewma = shm_ewma:get(upstream) or 0 + if not lock_ok then + return ewma, err + end + + local now = ngx_now() + local last_touched_at = shm_last_touched_at:get(upstream) or 0 + ewma = decay_ewma(ewma, last_touched_at, rtt, now) + + if not update then + return ewma Review comment:  Here is an example: ```lua local ok = lock() if not ok then end local ok, err = pcall(... ...) if not ok then log.error(... ...) end unlock() ``` ########## File path: apisix/balancer/ewma.lua ########## @@ -0,0 +1,240 @@ +-- +-- Licensed to the Apache Software Foundation (ASF) under one or more +-- contributor license agreements. See the NOTICE file distributed with +-- this work for additional information regarding copyright ownership. +-- The ASF licenses this file to You under the Apache License, Version 2.0 +-- (the "License"); you may not use this file except in compliance with +-- the License. You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +local resty_lock = require("resty.lock") +local core = require("apisix.core") +local ngx = ngx +local ngx_shared = ngx.shared +local ngx_now = ngx.now +local tostring = tostring +local math = math +local pairs = pairs +local next = next +local tonumber = tonumber + +local _M = {} +local DECAY_TIME = 10 -- this value is in seconds +local LOCK_KEY = ":ewma_key" +local PICK_SET_SIZE = 2 +local ewma_lock, ewma_lock_err +local shm_ewma = ngx_shared.balancer_ewma +local shm_last_touched_at= ngx_shared.balancer_ewma_last_touched_at + + +local function lock(upstream) + local _, err = ewma_lock:lock(upstream .. LOCK_KEY) + if err then + if err ~= "timeout" then + core.log.error("EWMA Balancer failed to lock:", err) + end + return false, err + end + + return true +end + + +local function unlock() + local ok, err = ewma_lock:unlock() + if not ok then + core.log.error("EWMA Balancer failed to unlock:", err) + return false, err + end + + return true +end + + +local function decay_ewma(ewma, last_touched_at, rtt, now) + local td = now - last_touched_at + td = math.max(td, 0) + local weight = math.exp(-td / DECAY_TIME) + + ewma = ewma * weight + rtt * (1.0 - weight) + return ewma +end + + +local function store_stats(upstream, ewma, now) + local success, err, forcible = shm_last_touched_at:set(upstream, now) + if not success then + core.log.error("balancer_ewma_last_touched_at:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma_last_touched_at:set valid items forcibly overwritten") + end + + success, err, forcible = shm_ewma:set(upstream, ewma) + if not success then + core.log.error("balancer_ewma:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma:set valid items forcibly overwritten") + end +end + + +local function get_or_update_ewma(upstream, rtt, update) + local lock_ok, err = nil + if update then + lock_ok, err = lock(upstream) + end + local ewma = shm_ewma:get(upstream) or 0 + if not lock_ok then + return ewma, err + end + + local now = ngx_now() + local last_touched_at = shm_last_touched_at:get(upstream) or 0 + ewma = decay_ewma(ewma, last_touched_at, rtt, now) + + if not update then + return ewma + end + + store_stats(upstream, ewma, now) + + unlock() + + return ewma +end + + +local function score(upstream) + -- Original implementation used names + -- Endpoints don't have names, so passing in IP:Port as key instead + local upstream_name = upstream.address .. ":" .. upstream.port + return get_or_update_ewma(upstream_name, 0, false) +end + + +-- implementation similar to https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle +-- or https://en.wikipedia.org/wiki/Random_permutation +-- loop from 1 .. k +-- pick a random value r from the remaining set of unpicked values (i .. n) +-- swap the value at position i with the value at position r +local function shuffle_peers(peers, k) + for i = 1, k do + local rand_index = math.random(i, #peers) + peers[i], peers[rand_index] = peers[rand_index], peers[i] + end +end + + +local function pick_and_score(peers, k) + shuffle_peers(peers, k) + local lowest_score_index = 1 + local lowest_score = score(peers[lowest_score_index]) + for i = 2, k do + local new_score = score(peers[i]) + if new_score < lowest_score then + lowest_score_index, lowest_score = i, new_score + end + end + + return peers[lowest_score_index], lowest_score +end + + +local function _trans_format(t1) + -- trans + --{"1.2.3.4:80":100,"5.6.7.8:8080":100} + -- into + -- [{"address":"1.2.3.4","port":"80"},{"address":"5.6.7.8","port":"8080"}] + local t2 = {} Review comment: we need a better name for `t1` and `t2` ########## File path: apisix/balancer/ewma.lua ########## @@ -0,0 +1,240 @@ +-- +-- Licensed to the Apache Software Foundation (ASF) under one or more +-- contributor license agreements. See the NOTICE file distributed with +-- this work for additional information regarding copyright ownership. +-- The ASF licenses this file to You under the Apache License, Version 2.0 +-- (the "License"); you may not use this file except in compliance with +-- the License. You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +local resty_lock = require("resty.lock") +local core = require("apisix.core") +local ngx = ngx +local ngx_shared = ngx.shared +local ngx_now = ngx.now +local tostring = tostring +local math = math +local pairs = pairs +local next = next +local tonumber = tonumber + +local _M = {} +local DECAY_TIME = 10 -- this value is in seconds +local LOCK_KEY = ":ewma_key" +local PICK_SET_SIZE = 2 +local ewma_lock, ewma_lock_err +local shm_ewma = ngx_shared.balancer_ewma +local shm_last_touched_at= ngx_shared.balancer_ewma_last_touched_at + + +local function lock(upstream) + local _, err = ewma_lock:lock(upstream .. LOCK_KEY) + if err then + if err ~= "timeout" then + core.log.error("EWMA Balancer failed to lock:", err) + end + return false, err + end + + return true +end + + +local function unlock() + local ok, err = ewma_lock:unlock() + if not ok then + core.log.error("EWMA Balancer failed to unlock:", err) + return false, err + end + + return true +end + + +local function decay_ewma(ewma, last_touched_at, rtt, now) + local td = now - last_touched_at + td = math.max(td, 0) + local weight = math.exp(-td / DECAY_TIME) + + ewma = ewma * weight + rtt * (1.0 - weight) + return ewma +end + + +local function store_stats(upstream, ewma, now) + local success, err, forcible = shm_last_touched_at:set(upstream, now) + if not success then + core.log.error("balancer_ewma_last_touched_at:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma_last_touched_at:set valid items forcibly overwritten") + end + + success, err, forcible = shm_ewma:set(upstream, ewma) + if not success then + core.log.error("balancer_ewma:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma:set valid items forcibly overwritten") + end +end + + +local function get_or_update_ewma(upstream, rtt, update) + local lock_ok, err = nil + if update then + lock_ok, err = lock(upstream) + end + local ewma = shm_ewma:get(upstream) or 0 + if not lock_ok then + return ewma, err + end + + local now = ngx_now() + local last_touched_at = shm_last_touched_at:get(upstream) or 0 + ewma = decay_ewma(ewma, last_touched_at, rtt, now) + + if not update then + return ewma + end + + store_stats(upstream, ewma, now) + + unlock() + + return ewma +end + + +local function score(upstream) + -- Original implementation used names + -- Endpoints don't have names, so passing in IP:Port as key instead + local upstream_name = upstream.address .. ":" .. upstream.port + return get_or_update_ewma(upstream_name, 0, false) +end + + +-- implementation similar to https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle +-- or https://en.wikipedia.org/wiki/Random_permutation +-- loop from 1 .. k +-- pick a random value r from the remaining set of unpicked values (i .. n) +-- swap the value at position i with the value at position r +local function shuffle_peers(peers, k) + for i = 1, k do + local rand_index = math.random(i, #peers) + peers[i], peers[rand_index] = peers[rand_index], peers[i] + end +end + + +local function pick_and_score(peers, k) + shuffle_peers(peers, k) + local lowest_score_index = 1 + local lowest_score = score(peers[lowest_score_index]) Review comment: `we need to capture this error message` ########## File path: apisix/balancer/ewma.lua ########## @@ -0,0 +1,240 @@ +-- +-- Licensed to the Apache Software Foundation (ASF) under one or more +-- contributor license agreements. See the NOTICE file distributed with +-- this work for additional information regarding copyright ownership. +-- The ASF licenses this file to You under the Apache License, Version 2.0 +-- (the "License"); you may not use this file except in compliance with +-- the License. You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +local resty_lock = require("resty.lock") +local core = require("apisix.core") +local ngx = ngx +local ngx_shared = ngx.shared +local ngx_now = ngx.now +local tostring = tostring +local math = math +local pairs = pairs +local next = next +local tonumber = tonumber + +local _M = {} +local DECAY_TIME = 10 -- this value is in seconds +local LOCK_KEY = ":ewma_key" +local PICK_SET_SIZE = 2 +local ewma_lock, ewma_lock_err +local shm_ewma = ngx_shared.balancer_ewma +local shm_last_touched_at= ngx_shared.balancer_ewma_last_touched_at + + +local function lock(upstream) + local _, err = ewma_lock:lock(upstream .. LOCK_KEY) + if err then + if err ~= "timeout" then + core.log.error("EWMA Balancer failed to lock:", err) + end + return false, err + end + + return true +end + + +local function unlock() + local ok, err = ewma_lock:unlock() + if not ok then + core.log.error("EWMA Balancer failed to unlock:", err) + return false, err + end + + return true +end + + +local function decay_ewma(ewma, last_touched_at, rtt, now) + local td = now - last_touched_at + td = math.max(td, 0) + local weight = math.exp(-td / DECAY_TIME) + + ewma = ewma * weight + rtt * (1.0 - weight) + return ewma +end + + +local function store_stats(upstream, ewma, now) + local success, err, forcible = shm_last_touched_at:set(upstream, now) + if not success then + core.log.error("balancer_ewma_last_touched_at:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma_last_touched_at:set valid items forcibly overwritten") + end + + success, err, forcible = shm_ewma:set(upstream, ewma) + if not success then + core.log.error("balancer_ewma:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma:set valid items forcibly overwritten") + end +end + + +local function get_or_update_ewma(upstream, rtt, update) + local lock_ok, err = nil + if update then + lock_ok, err = lock(upstream) + end + local ewma = shm_ewma:get(upstream) or 0 + if not lock_ok then + return ewma, err + end + + local now = ngx_now() + local last_touched_at = shm_last_touched_at:get(upstream) or 0 + ewma = decay_ewma(ewma, last_touched_at, rtt, now) + + if not update then + return ewma + end + + store_stats(upstream, ewma, now) + + unlock() + + return ewma +end + + +local function score(upstream) + -- Original implementation used names + -- Endpoints don't have names, so passing in IP:Port as key instead + local upstream_name = upstream.address .. ":" .. upstream.port + return get_or_update_ewma(upstream_name, 0, false) +end + + +-- implementation similar to https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle +-- or https://en.wikipedia.org/wiki/Random_permutation +-- loop from 1 .. k +-- pick a random value r from the remaining set of unpicked values (i .. n) +-- swap the value at position i with the value at position r +local function shuffle_peers(peers, k) + for i = 1, k do + local rand_index = math.random(i, #peers) + peers[i], peers[rand_index] = peers[rand_index], peers[i] + end +end + + +local function pick_and_score(peers, k) + shuffle_peers(peers, k) + local lowest_score_index = 1 + local lowest_score = score(peers[lowest_score_index]) + for i = 2, k do + local new_score = score(peers[i]) + if new_score < lowest_score then + lowest_score_index, lowest_score = i, new_score + end + end + + return peers[lowest_score_index], lowest_score +end + + +local function _trans_format(t1) + -- trans + --{"1.2.3.4:80":100,"5.6.7.8:8080":100} + -- into + -- [{"address":"1.2.3.4","port":"80"},{"address":"5.6.7.8","port":"8080"}] + local t2 = {} + local addr, port, err + + for k,_ in pairs(t1) do Review comment: `k,_` -> `key, _` ########## File path: apisix/balancer/ewma.lua ########## @@ -0,0 +1,240 @@ +-- +-- Licensed to the Apache Software Foundation (ASF) under one or more +-- contributor license agreements. See the NOTICE file distributed with +-- this work for additional information regarding copyright ownership. +-- The ASF licenses this file to You under the Apache License, Version 2.0 +-- (the "License"); you may not use this file except in compliance with +-- the License. You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +local resty_lock = require("resty.lock") +local core = require("apisix.core") +local ngx = ngx +local ngx_shared = ngx.shared +local ngx_now = ngx.now +local tostring = tostring +local math = math +local pairs = pairs +local next = next +local tonumber = tonumber + +local _M = {} +local DECAY_TIME = 10 -- this value is in seconds +local LOCK_KEY = ":ewma_key" +local PICK_SET_SIZE = 2 +local ewma_lock, ewma_lock_err +local shm_ewma = ngx_shared.balancer_ewma +local shm_last_touched_at= ngx_shared.balancer_ewma_last_touched_at + + +local function lock(upstream) + local _, err = ewma_lock:lock(upstream .. LOCK_KEY) + if err then + if err ~= "timeout" then + core.log.error("EWMA Balancer failed to lock:", err) + end + return false, err + end + + return true +end + + +local function unlock() + local ok, err = ewma_lock:unlock() + if not ok then + core.log.error("EWMA Balancer failed to unlock:", err) + return false, err + end + + return true +end + + +local function decay_ewma(ewma, last_touched_at, rtt, now) + local td = now - last_touched_at + td = math.max(td, 0) + local weight = math.exp(-td / DECAY_TIME) + + ewma = ewma * weight + rtt * (1.0 - weight) + return ewma +end + + +local function store_stats(upstream, ewma, now) + local success, err, forcible = shm_last_touched_at:set(upstream, now) + if not success then + core.log.error("balancer_ewma_last_touched_at:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma_last_touched_at:set valid items forcibly overwritten") + end + + success, err, forcible = shm_ewma:set(upstream, ewma) + if not success then + core.log.error("balancer_ewma:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma:set valid items forcibly overwritten") + end +end + + +local function get_or_update_ewma(upstream, rtt, update) + local lock_ok, err = nil + if update then + lock_ok, err = lock(upstream) + end + local ewma = shm_ewma:get(upstream) or 0 + if not lock_ok then + return ewma, err + end + + local now = ngx_now() + local last_touched_at = shm_last_touched_at:get(upstream) or 0 + ewma = decay_ewma(ewma, last_touched_at, rtt, now) + + if not update then + return ewma + end + + store_stats(upstream, ewma, now) + + unlock() + + return ewma +end + + +local function score(upstream) + -- Original implementation used names + -- Endpoints don't have names, so passing in IP:Port as key instead + local upstream_name = upstream.address .. ":" .. upstream.port + return get_or_update_ewma(upstream_name, 0, false) +end + + +-- implementation similar to https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle +-- or https://en.wikipedia.org/wiki/Random_permutation +-- loop from 1 .. k +-- pick a random value r from the remaining set of unpicked values (i .. n) +-- swap the value at position i with the value at position r +local function shuffle_peers(peers, k) + for i = 1, k do + local rand_index = math.random(i, #peers) + peers[i], peers[rand_index] = peers[rand_index], peers[i] + end +end + + +local function pick_and_score(peers, k) Review comment: bad name for `k`, I don't know what is mean. ########## File path: apisix/balancer/ewma.lua ########## @@ -0,0 +1,240 @@ +-- +-- Licensed to the Apache Software Foundation (ASF) under one or more +-- contributor license agreements. See the NOTICE file distributed with +-- this work for additional information regarding copyright ownership. +-- The ASF licenses this file to You under the Apache License, Version 2.0 +-- (the "License"); you may not use this file except in compliance with +-- the License. You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +local resty_lock = require("resty.lock") +local core = require("apisix.core") +local ngx = ngx +local ngx_shared = ngx.shared +local ngx_now = ngx.now +local tostring = tostring +local math = math +local pairs = pairs +local next = next +local tonumber = tonumber + +local _M = {} +local DECAY_TIME = 10 -- this value is in seconds +local LOCK_KEY = ":ewma_key" +local PICK_SET_SIZE = 2 +local ewma_lock, ewma_lock_err +local shm_ewma = ngx_shared.balancer_ewma +local shm_last_touched_at= ngx_shared.balancer_ewma_last_touched_at + + +local function lock(upstream) + local _, err = ewma_lock:lock(upstream .. LOCK_KEY) + if err then + if err ~= "timeout" then + core.log.error("EWMA Balancer failed to lock:", err) + end + return false, err + end + + return true +end + + +local function unlock() + local ok, err = ewma_lock:unlock() + if not ok then + core.log.error("EWMA Balancer failed to unlock:", err) + return false, err + end + + return true +end + + +local function decay_ewma(ewma, last_touched_at, rtt, now) + local td = now - last_touched_at + td = math.max(td, 0) + local weight = math.exp(-td / DECAY_TIME) + + ewma = ewma * weight + rtt * (1.0 - weight) + return ewma +end + + +local function store_stats(upstream, ewma, now) + local success, err, forcible = shm_last_touched_at:set(upstream, now) + if not success then + core.log.error("balancer_ewma_last_touched_at:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma_last_touched_at:set valid items forcibly overwritten") + end + + success, err, forcible = shm_ewma:set(upstream, ewma) + if not success then + core.log.error("balancer_ewma:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma:set valid items forcibly overwritten") + end +end + + +local function get_or_update_ewma(upstream, rtt, update) + local lock_ok, err = nil + if update then + lock_ok, err = lock(upstream) + end + local ewma = shm_ewma:get(upstream) or 0 + if not lock_ok then + return ewma, err + end + + local now = ngx_now() + local last_touched_at = shm_last_touched_at:get(upstream) or 0 + ewma = decay_ewma(ewma, last_touched_at, rtt, now) + + if not update then + return ewma + end + + store_stats(upstream, ewma, now) + + unlock() + + return ewma +end + + +local function score(upstream) + -- Original implementation used names + -- Endpoints don't have names, so passing in IP:Port as key instead + local upstream_name = upstream.address .. ":" .. upstream.port + return get_or_update_ewma(upstream_name, 0, false) +end + + +-- implementation similar to https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle +-- or https://en.wikipedia.org/wiki/Random_permutation +-- loop from 1 .. k +-- pick a random value r from the remaining set of unpicked values (i .. n) +-- swap the value at position i with the value at position r +local function shuffle_peers(peers, k) + for i = 1, k do + local rand_index = math.random(i, #peers) + peers[i], peers[rand_index] = peers[rand_index], peers[i] + end +end + + +local function pick_and_score(peers, k) + shuffle_peers(peers, k) + local lowest_score_index = 1 + local lowest_score = score(peers[lowest_score_index]) + for i = 2, k do + local new_score = score(peers[i]) + if new_score < lowest_score then + lowest_score_index, lowest_score = i, new_score + end + end + + return peers[lowest_score_index], lowest_score +end + + +local function _trans_format(t1) + -- trans + --{"1.2.3.4:80":100,"5.6.7.8:8080":100} + -- into + -- [{"address":"1.2.3.4","port":"80"},{"address":"5.6.7.8","port":"8080"}] + local t2 = {} + local addr, port, err + + for k,_ in pairs(t1) do + addr, port, err = core.utils.parse_addr(k) + if not err then + core.table.insert(t2, {address = addr, port = tostring(port)}) + else + core.log.error('parse_addr error: ', k, err) + end + end + + return next(t2) and t2 or nil +end + + +local function _ewma_find(up_nodes) + local peers + local endpoint + local err + + if not ewma_lock then + ewma_lock, ewma_lock_err = resty_lock:new("balancer_ewma_locks", + {timeout = 0, exptime = 0.1}) + end + if not ewma_lock then + return nil, ewma_lock_err + end + peers = _trans_format(up_nodes) + if not peers then + err = 'up_nodes error' + return nil, err + end + endpoint = peers[1] Review comment: another style, clearer: ```lua if #peers > 1 then ... ... else endpoint = peers[1] end ``` ########## File path: apisix/balancer/ewma.lua ########## @@ -0,0 +1,240 @@ +-- +-- Licensed to the Apache Software Foundation (ASF) under one or more +-- contributor license agreements. See the NOTICE file distributed with +-- this work for additional information regarding copyright ownership. +-- The ASF licenses this file to You under the Apache License, Version 2.0 +-- (the "License"); you may not use this file except in compliance with +-- the License. You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +local resty_lock = require("resty.lock") +local core = require("apisix.core") +local ngx = ngx +local ngx_shared = ngx.shared +local ngx_now = ngx.now +local tostring = tostring +local math = math +local pairs = pairs +local next = next +local tonumber = tonumber + +local _M = {} +local DECAY_TIME = 10 -- this value is in seconds +local LOCK_KEY = ":ewma_key" +local PICK_SET_SIZE = 2 +local ewma_lock, ewma_lock_err +local shm_ewma = ngx_shared.balancer_ewma +local shm_last_touched_at= ngx_shared.balancer_ewma_last_touched_at + + +local function lock(upstream) + local _, err = ewma_lock:lock(upstream .. LOCK_KEY) + if err then + if err ~= "timeout" then + core.log.error("EWMA Balancer failed to lock:", err) + end + return false, err + end + + return true +end + + +local function unlock() + local ok, err = ewma_lock:unlock() + if not ok then + core.log.error("EWMA Balancer failed to unlock:", err) + return false, err + end + + return true +end + + +local function decay_ewma(ewma, last_touched_at, rtt, now) + local td = now - last_touched_at + td = math.max(td, 0) + local weight = math.exp(-td / DECAY_TIME) + + ewma = ewma * weight + rtt * (1.0 - weight) + return ewma +end + + +local function store_stats(upstream, ewma, now) + local success, err, forcible = shm_last_touched_at:set(upstream, now) + if not success then + core.log.error("balancer_ewma_last_touched_at:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma_last_touched_at:set valid items forcibly overwritten") + end + + success, err, forcible = shm_ewma:set(upstream, ewma) + if not success then + core.log.error("balancer_ewma:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma:set valid items forcibly overwritten") + end +end + + +local function get_or_update_ewma(upstream, rtt, update) + local lock_ok, err = nil + if update then + lock_ok, err = lock(upstream) + end + local ewma = shm_ewma:get(upstream) or 0 + if not lock_ok then + return ewma, err + end + + local now = ngx_now() + local last_touched_at = shm_last_touched_at:get(upstream) or 0 + ewma = decay_ewma(ewma, last_touched_at, rtt, now) + + if not update then + return ewma + end + + store_stats(upstream, ewma, now) + + unlock() + + return ewma +end + + +local function score(upstream) + -- Original implementation used names + -- Endpoints don't have names, so passing in IP:Port as key instead + local upstream_name = upstream.address .. ":" .. upstream.port + return get_or_update_ewma(upstream_name, 0, false) +end + + +-- implementation similar to https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle +-- or https://en.wikipedia.org/wiki/Random_permutation +-- loop from 1 .. k +-- pick a random value r from the remaining set of unpicked values (i .. n) +-- swap the value at position i with the value at position r +local function shuffle_peers(peers, k) + for i = 1, k do + local rand_index = math.random(i, #peers) + peers[i], peers[rand_index] = peers[rand_index], peers[i] + end +end + + +local function pick_and_score(peers, k) + shuffle_peers(peers, k) + local lowest_score_index = 1 + local lowest_score = score(peers[lowest_score_index]) + for i = 2, k do + local new_score = score(peers[i]) + if new_score < lowest_score then + lowest_score_index, lowest_score = i, new_score + end + end + + return peers[lowest_score_index], lowest_score +end + + +local function _trans_format(t1) + -- trans + --{"1.2.3.4:80":100,"5.6.7.8:8080":100} + -- into + -- [{"address":"1.2.3.4","port":"80"},{"address":"5.6.7.8","port":"8080"}] + local t2 = {} + local addr, port, err + + for k,_ in pairs(t1) do + addr, port, err = core.utils.parse_addr(k) + if not err then + core.table.insert(t2, {address = addr, port = tostring(port)}) + else + core.log.error('parse_addr error: ', k, err) + end + end + + return next(t2) and t2 or nil +end + + +local function _ewma_find(up_nodes) + local peers + local endpoint + local err + + if not ewma_lock then + ewma_lock, ewma_lock_err = resty_lock:new("balancer_ewma_locks", + {timeout = 0, exptime = 0.1}) + end + if not ewma_lock then + return nil, ewma_lock_err + end + peers = _trans_format(up_nodes) + if not peers then + err = 'up_nodes error' + return nil, err + end + endpoint = peers[1] + if #peers > 1 then + local k = (#peers < PICK_SET_SIZE) and #peers or PICK_SET_SIZE + endpoint = pick_and_score(peers, k) + end + + return endpoint.address .. ":" .. endpoint.port +end + + +local function _ewma_after_balance(ctx) + local response_time = tonumber(ctx.var.upstream_response_time) or 0 + local connect_time = tonumber(ctx.var.upstream_connect_time) or 0 + local rtt = connect_time + response_time + local upstream = ctx.var.upstream_addr + + if not ewma_lock then + ewma_lock, ewma_lock_err = resty_lock:new("balancer_ewma_locks", + {timeout = 0, exptime = 0.1}) Review comment: bad performance style. need a way to reuse the table, avoid temporary table. ```lua local lock_opts = {timeout = 0, exptime = 0.1} local function _ewma_after_balance(ctx) ... ... ewma_lock, ewma_lock_err = resty_lock:new("balancer_ewma_locks", lock_opts) ... ... end ``` ########## File path: apisix/balancer/ewma.lua ########## @@ -0,0 +1,240 @@ +-- +-- Licensed to the Apache Software Foundation (ASF) under one or more +-- contributor license agreements. See the NOTICE file distributed with +-- this work for additional information regarding copyright ownership. +-- The ASF licenses this file to You under the Apache License, Version 2.0 +-- (the "License"); you may not use this file except in compliance with +-- the License. You may obtain a copy of the License at +-- +-- http://www.apache.org/licenses/LICENSE-2.0 +-- +-- Unless required by applicable law or agreed to in writing, software +-- distributed under the License is distributed on an "AS IS" BASIS, +-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +-- See the License for the specific language governing permissions and +-- limitations under the License. +-- + +local resty_lock = require("resty.lock") +local core = require("apisix.core") +local ngx = ngx +local ngx_shared = ngx.shared +local ngx_now = ngx.now +local tostring = tostring +local math = math +local pairs = pairs +local next = next +local tonumber = tonumber + +local _M = {} +local DECAY_TIME = 10 -- this value is in seconds +local LOCK_KEY = ":ewma_key" +local PICK_SET_SIZE = 2 +local ewma_lock, ewma_lock_err +local shm_ewma = ngx_shared.balancer_ewma +local shm_last_touched_at= ngx_shared.balancer_ewma_last_touched_at + + +local function lock(upstream) + local _, err = ewma_lock:lock(upstream .. LOCK_KEY) + if err then + if err ~= "timeout" then + core.log.error("EWMA Balancer failed to lock:", err) + end + return false, err + end + + return true +end + + +local function unlock() + local ok, err = ewma_lock:unlock() + if not ok then + core.log.error("EWMA Balancer failed to unlock:", err) + return false, err + end + + return true +end + + +local function decay_ewma(ewma, last_touched_at, rtt, now) + local td = now - last_touched_at + td = math.max(td, 0) + local weight = math.exp(-td / DECAY_TIME) + + ewma = ewma * weight + rtt * (1.0 - weight) + return ewma +end + + +local function store_stats(upstream, ewma, now) + local success, err, forcible = shm_last_touched_at:set(upstream, now) + if not success then + core.log.error("balancer_ewma_last_touched_at:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma_last_touched_at:set valid items forcibly overwritten") + end + + success, err, forcible = shm_ewma:set(upstream, ewma) + if not success then + core.log.error("balancer_ewma:set failed ", err) + end + if forcible then + core.log.warn("balancer_ewma:set valid items forcibly overwritten") + end +end + + +local function get_or_update_ewma(upstream, rtt, update) + local lock_ok, err = nil + if update then + lock_ok, err = lock(upstream) + end + local ewma = shm_ewma:get(upstream) or 0 + if not lock_ok then + return ewma, err + end + + local now = ngx_now() + local last_touched_at = shm_last_touched_at:get(upstream) or 0 + ewma = decay_ewma(ewma, last_touched_at, rtt, now) + + if not update then + return ewma + end + + store_stats(upstream, ewma, now) + + unlock() + + return ewma +end + + +local function score(upstream) + -- Original implementation used names + -- Endpoints don't have names, so passing in IP:Port as key instead + local upstream_name = upstream.address .. ":" .. upstream.port + return get_or_update_ewma(upstream_name, 0, false) +end + + +-- implementation similar to https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle +-- or https://en.wikipedia.org/wiki/Random_permutation +-- loop from 1 .. k +-- pick a random value r from the remaining set of unpicked values (i .. n) +-- swap the value at position i with the value at position r +local function shuffle_peers(peers, k) + for i = 1, k do + local rand_index = math.random(i, #peers) + peers[i], peers[rand_index] = peers[rand_index], peers[i] + end +end + + +local function pick_and_score(peers, k) + shuffle_peers(peers, k) + local lowest_score_index = 1 + local lowest_score = score(peers[lowest_score_index]) + for i = 2, k do + local new_score = score(peers[i]) + if new_score < lowest_score then + lowest_score_index, lowest_score = i, new_score + end + end + + return peers[lowest_score_index], lowest_score +end + + +local function _trans_format(t1) + -- trans + --{"1.2.3.4:80":100,"5.6.7.8:8080":100} + -- into + -- [{"address":"1.2.3.4","port":"80"},{"address":"5.6.7.8","port":"8080"}] + local t2 = {} + local addr, port, err + + for k,_ in pairs(t1) do + addr, port, err = core.utils.parse_addr(k) + if not err then + core.table.insert(t2, {address = addr, port = tostring(port)}) + else + core.log.error('parse_addr error: ', k, err) + end + end + + return next(t2) and t2 or nil +end + + +local function _ewma_find(up_nodes) + local peers + local endpoint + local err + + if not ewma_lock then + ewma_lock, ewma_lock_err = resty_lock:new("balancer_ewma_locks", + {timeout = 0, exptime = 0.1}) + end + if not ewma_lock then + return nil, ewma_lock_err + end + peers = _trans_format(up_nodes) Review comment: I think we can use a `lrucache` to get the `peers`, avoid to generate `peer` for every time. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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