Fix OpenResty race condition from global logging variable initialization

[Copilot]

The lualogging library creates a global logging variable at module load time. In OpenResty's concurrent environment, multiple workers initializing this global simultaneously causes race condition warnings and potential failures when creating multiple Enforcer instances.

Changes

• Lazy load logging dependencies in src/util/Log.lua

  • Moved require "logging" inside getLogger()
  • Moved require "logging.file" inside getFileLogger()
  • Defers initialization until function call, avoiding concurrent module-level execution

• Added regression test in tests/main/multi_enforcer_spec.lua

  • Validates multiple newEnforcerFromText calls work without race conditions
  • Covers the exact scenario from the reported issue

Example

Before:

-- Module-level requires execute during init, causing race conditions
local Logging = require "logging"
local fileLogging = require "logging.file"

function Log.getLogger()
    -- Uses already-loaded Logging
end

After:

function Log.getLogger()
    -- Load only when needed, in request context
    local Logging = require "logging"
    -- ... rest of implementation
end

Lua's require caches modules, so subsequent calls return the cached instance without re-execution.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>ERROR: invalid request size</issue_title>
<issue_description>>test code

local Enforcer1 = require("casbin")
local Enforcer2 = require("casbin")

local model1 = [[
    [request_definition]
    r = path, method

    [policy_definition]
    p = path, method, eft

    [policy_effect]
    e = some(where (p.eft == allow)) && !some(where (p.eft == deny))

    [matchers]
    m = regexMatch(r.path, p.path) && keyMatch(r.method, p.method)
]]

local policy1 =[[
    p, ^/cate/sample/gen_label_no,              POST, allow
    p, ^/cate/sample/.*/[print|reprint],        PUT,  allow
]]

local model2 = [[
    [request_definition]
r = user, path, method

[policy_definition]
p = role, path, method

[role_definition]
g = _, _

[policy_effect]
e = some(where (p.eft == allow))

[matchers]
m = (g(r.user, p.role) || keyMatch(r.user, p.role)) && regexMatch(r.path, p.path) && keyMatch(r.method, p.method)
]]

local policy2 =[[

p, *,          ^/$,                         GET
p, *,          ^/portal,                    GET
p, *,          ^/admin,                     GET

p, sys-admin,  *,                           *
g, sys-admin,       guests
]]

local ex2 = Enforcer2:newEnforcerFromText(model2, policy2)

local pass2 =  ex2:enforce("guests", "/", "GET")
print( "pass2:",pass2)



local ex1 = Enforcer1:newEnforcerFromText(model1, policy1)

local pass1 =  ex1:enforce("/cate/sample/gen_label_no", "POST")
print( "pass1: ",pass1)


local pass3 =  ex2:enforce("guests", "/", "GET")

print( "pass3: ",pass3)

error info

$ resty t-casbin.lua                                                                                                                                           [18:08:36]
2023/10/05 18:08:38 [warn] 2508#0: *2 [lua] _G write guard:12: __newindex(): writing a global Lua variable ('logging') which may lead to race conditions between concurrent requests, so prefer the use of 'local' variables
stack traceback:
        /usr/local/openresty/luajit/share/lua/5.1/logging.lua:465: in main chunk
        [C]: in function 'require'
        /usr/local/openresty/luajit/share/lua/5.1/src/util/Log.lua:15: in main chunk
        [C]: in function 'require'
        ...ocal/openresty/luajit/share/lua/5.1/src/model/Policy.lua:16: in main chunk
        [C]: in function 'require'
        ...local/openresty/luajit/share/lua/5.1/src/model/Model.lua:16: in main chunk
        [C]: in function 'require'
        ...openresty/luajit/share/lua/5.1/src/main/CoreEnforcer.lua:18: in main chunk
        [C]: in function 'require'
        ...
        ...sty/luajit/share/lua/5.1/src/main/ManagementEnforcer.lua:15: in main chunk
        [C]: in function 'require'
        ...cal/openresty/luajit/share/lua/5.1/src/main/Enforcer.lua:15: in main chunk
        [C]: in function 'require'
        /usr/local/openresty/luajit/share/lua/5.1/casbin.lua:16: in main chunk
        [C]: in function 'require'
        t-casbin.lua:1: in function 'file_gen'
        init_worker_by_lua(nginx.conf:185):45: in function <init_worker_by_lua(nginx.conf:185):43>
        [C]: in function 'xpcall'
        init_worker_by_lua(nginx.conf:185):52: in function <init_worker_by_lua(nginx.conf:185):50>, context: ngx.timer
INFOModel: 

INFO[e.e]:
INFO{RM = {}, key = "e", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {}, value = "some(where (p_eft == allow))"}
INFO[g.g]:
INFO{RM = {}, key = "g", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {}, value = "_, _"}
INFO[r.r]:
INFO{RM = {}, key = "r", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {"r_user", "r_path", "r_method"}, value = "user, path, method"}
INFO[p.p]:
INFO{RM = {}, key = "p", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {"p_role", "p_path", "p_method"}, value = "role, path, method"}
INFO[m.m]:
INFO{RM = {}, key = "m", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {}, value = "(g(r_user, p_role) || keyMatch(r_user, p_role)) && regexMatch(r_path, p_path) && keyMatch(r_method, p_method)"}
INFORequest: guests, /, GET ---> true
Hit Policy: { *, ^/$, GET }
pass2:true
INFOModel: 

INFO[p.p]:
INFO{RM = {}, key = "p", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {"p_path", "p_method", "p_eft"}, value = "path, method, eft"}
INFO[m.m]:
INFO{RM = {}, key = "m", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {}, value = "regexMatch(r_path, p_path) && keyMatch(r_method, p_method)"}
INFO[e.e]:
INFO{RM = {}, key = "e", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {}, value = "some(where (p_eft == allow)) && !some(where (p_eft == deny))"}
INFO[r.r]:
INFO{RM = {}, key = "r", policy = {}, policyMap = {}, priorityIndex = -1, tokens = {"r_path", "r_method"}, value = "path, method"}
INFORequest: /cate/sample/gen_label_no, POST ---> true

pass1...

</details>



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- Fixes casbin/lua-casbin#152

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