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trace function call chains while reading the lua source
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| -- Trace request context exclusively within Lua projects | |
| -- executed by the Lua-nginx-module | |
| -- | |
| -- The timer context is not available within functions triggered by | |
| -- ngx.timer.at(). However, you can easily make adjustments to this file to | |
| -- enable it. | |
| -- | |
| -- In your lua source file: | |
| -- require("bt").init_hook() | |
| -- true : it displays the level number of the calling function. | |
| -- false: it displays space-based indentation determined by the level number. | |
| local DISPLAY_LEVEL_NUMBER = false | |
| local _M = {} | |
| function _M.init_hook() | |
| if not ngx.ctx then | |
| return nil | |
| end | |
| local _t = { | |
| level = 0, | |
| call_chains = {}, -- array[] | |
| id = string.sub(ngx.var.request_id, 1, 8), | |
| } | |
| ngx.ctx._trace_info = _t | |
| setmetatable(_M, {}) | |
| return _t | |
| end | |
| local function trace_skip(info) | |
| if not info or not info.name then | |
| return true | |
| end | |
| -- skip inline function, such as print() | |
| if info.source == "[C]" or info.currentline == -1 then | |
| return true | |
| end | |
| -- skip myself | |
| if string.find(info.source, "/bt.lua") or info.name == "init_hook" then | |
| return true | |
| end | |
| -- not kong source (maybe required library) | |
| if string.find(info.source, "/openresty/") | |
| or string.find(info.source, "/lualib/") | |
| or string.find(info.source, "/lua/5%.[123]/") | |
| then | |
| return true | |
| end | |
| return false | |
| end | |
| -- This function will be called whenever a function is called or returns | |
| local function trace_hook(event) | |
| -- skip timer | |
| -- request context | |
| if not ngx.ctx then | |
| return | |
| end | |
| local _t = ngx.ctx._trace_info | |
| if not _t then | |
| return | |
| end | |
| local info = debug.getinfo(2, "nSl") | |
| if trace_skip(info) then | |
| return | |
| end | |
| -- evaluate | |
| local func_name = info.name | |
| local line_info = info.short_src .. ":" .. (info.currentline or "unknown") | |
| local prefix, s | |
| local level = _t.level | |
| local event_prefix = ">" | |
| if event == "call" then | |
| _t.level = level + 1 | |
| _t.call_chains[_t.level] = func_name | |
| elseif event == "return" then | |
| event_prefix = "< (no caller)" | |
| -- fix that some function has no return event (e.g. __index [C]:-1) | |
| local i = level | |
| while i > 0 do | |
| local orig_func_name = _t.call_chains[i] | |
| i = i - 1 | |
| -- print("[DD] call chain pop:", orig_func_name, " return func:", func_name) | |
| if orig_func_name == func_name then | |
| _t.level = i | |
| level = i | |
| event_prefix = "<" | |
| break | |
| end | |
| end | |
| else | |
| event_prefix = "?" | |
| end | |
| if DISPLAY_LEVEL_NUMBER then | |
| prefix = tostring(level) | |
| else | |
| prefix = string.rep(" ", level) | |
| end | |
| s = string.format("%s: %s %s %s() %s", | |
| _t.id, prefix, event_prefix, func_name, line_info) | |
| -- show | |
| ngx.log(ngx.ERR, "\nHook: [" .. s .. "]\n") | |
| -- print(s) | |
| end | |
| local function init() | |
| debug.sethook(trace_hook, "cr") | |
| --[[ | |
| if jit then | |
| jit.off() | |
| end | |
| ]] | |
| end | |
| init() | |
| return _M |
- TODO: Some inline C functions (or other situation) may not trigger a return event. We are actively working to address this issue within the call chain to ensure a balanced call/return depth level. However, especially when there are consecutive calls to inline functions, which makes call depth level increases.
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For kong project, how to use
Description of Log Fields
result from nginx error.log