refactor some lua code

rootfs/etc/nginx/lua/util/defer.lua

@@ -0,0 +1,57 @@
+local util = require("util")
+
+local timer_started = false
+local queue = {}
+local MAX_QUEUE_SIZE = 10000
+
+local _M = {}
+
+local function flush_queue(premature)
+  -- TODO Investigate if we should actually still flush the queue when we're
+  -- shutting down.
+  if premature then return end
+
+  local current_queue = queue
+  queue = {}
+  timer_started = false
+
+  for _,v in ipairs(current_queue) do
+    v.func(unpack(v.args))
+  end
+end
+
+-- `to_timer_phase` will enqueue a function that will be executed in a timer
+-- context, at a later point in time. The purpose is that some APIs (such as
+-- sockets) are not available during some nginx request phases (such as the
+-- logging phase), but are available for use in timers. There are no ordering
+-- guarantees for when a function will be executed.
+function _M.to_timer_phase(func, ...)
+  if ngx.get_phase() == "timer" then
+    func(...)
+    return true
+  end
+
+  if #queue >= MAX_QUEUE_SIZE then
+    ngx.log(ngx.ERR, "deferred timer queue full")
+    return nil, "deferred timer queue full"
+  end
+
+  table.insert(queue, { func = func, args = {...} })
+  if not timer_started then
+    local ok, err = ngx.timer.at(0, flush_queue)
+    if ok then
+      -- unfortunately this is to deal with tests - when running unit tests, we
+      -- dont actually run the timer, we call the function inline
+      if util.tablelength(queue) > 0 then
+        timer_started = true
+      end
+    else
+      local msg = "failed to create timer: " .. tostring(err)
+      ngx.log(ngx.ERR, msg)
+      return nil, msg
+    end
+  end
+  return true
+end
+
+return _M

rootfs/etc/nginx/lua/util/split.lua

@@ -0,0 +1,70 @@
+local _M = {}
+
+-- splits strings into host and port
+local function parse_addr(addr)
+  local _, _, host, port = addr:find("([^:]+):([^:]+)")
+  if host and port then
+    return {host=host, port=port}
+  else
+    return nil, "error in parsing upstream address!"
+  end
+end
+
+function _M.get_first_value(var)
+  local t = _M.split_upstream_var(var) or {}
+  if #t == 0 then return nil end
+  return t[1]
+end
+
+function _M.split_pair(pair, seperator)
+  local i = pair:find(seperator)
+  if i == nil then
+    return pair, nil
+  else
+    local name = pair:sub(1, i - 1)
+    local value = pair:sub(i + 1, -1)
+    return name, value
+  end
+end
+
+-- http://nginx.org/en/docs/http/ngx_http_upstream_module.html#example
+-- CAVEAT: nginx is giving out : instead of , so the docs are wrong
+-- 127.0.0.1:26157 : 127.0.0.1:26157 , ngx.var.upstream_addr
+-- 200 : 200 , ngx.var.upstream_status
+-- 0.00 : 0.00, ngx.var.upstream_response_time
+function _M.split_upstream_var(var)
+  if not var then
+    return nil, nil
+  end
+  local t = {}
+  for v in var:gmatch("[^%s|,]+") do
+    if v ~= ":" then
+      t[#t+1] = v
+    end
+  end
+  return t
+end
+
+-- Splits an NGINX $upstream_addr and returns an array of tables with a `host` and `port` key-value pair.
+function _M.split_upstream_addr(addrs_str)
+  if not addrs_str then
+    return nil, nil
+  end
+
+  local addrs = _M.split_upstream_var(addrs_str)
+  local host_and_ports = {}
+
+  for _, v in ipairs(addrs) do
+    local a, err = parse_addr(v)
+    if err then
+      return nil, err
+    end
+    host_and_ports[#host_and_ports+1] = a
+  end
+  if #host_and_ports == 0 then
+    return nil, "no upstream addresses to parse!"
+  end
+  return host_and_ports
+end
+
+return _M