From a491594775cb32773798a4acb5e278e0765a498e Mon Sep 17 00:00:00 2001
From: chrox <chrox.huang@gmail.com>
Date: Fri, 3 Oct 2014 16:07:38 +0800
Subject: [PATCH] trace package loading process in koreader

---
 utils/trace_require.lua | 47 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 utils/trace_require.lua

diff --git a/utils/trace_require.lua b/utils/trace_require.lua
new file mode 100644
index 000000000..a5e00668d
--- /dev/null
+++ b/utils/trace_require.lua
@@ -0,0 +1,47 @@
+-- trace package loading flow with require call
+-- usage: ./luajit -lutils/trace_require reader.lua ../../test
+
+local math = require("math")
+local _require = require
+
+local loaded_modules = {}
+local highlight = "*"
+-- timing threshold for highlight annotation
+local threshold = 0.001
+-- whether to trace loaded packages
+local trace_loaded = false
+local indent = string.rep(" ", 4)
+
+local level = 0
+function require(module)
+    level = level + 1
+    local x = os.clock()
+    local info = debug.getinfo(2)
+    -- this is a protected call of require
+    if info.short_src == "[C]" then
+        info = debug.getinfo(3)
+    end
+    local loaded = loaded_modules[module]
+    if not loaded then
+        print(string.format("%s%s:%s => %s",
+            indent:rep(level), info.short_src, info.currentline, module))
+    elseif trace_loaded then
+        print(string.format("%s%s:%s -> %s",
+            indent:rep(level), info.short_src, info.currentline, module))
+    end
+    -- protect require call in case we cannot raise call level when errors happen
+    local ok, loaded_module = pcall(_require, module)
+    if not ok then
+        level = level - 1
+        error(loaded_module)
+    end
+    local elapse = os.clock() - x
+    local annot = highlight:rep(math.ceil(math.log10(elapse/threshold))) or ""
+    if not loaded then
+        print(string.format("%s%s loading time: %.3f",
+            annot .. indent:rep(level):sub(#annot + 1), module, elapse))
+    end
+    loaded_modules[module] = true
+    level = level - 1
+    return loaded_module
+end