add resty.uuid wrapper

README.markdown

@@ -148,6 +148,10 @@ Synopsis
         aes_256_cbc_sha512x5:decrypt(encrypted))
 
 
+    -- uuid test
+    local resty_uuid = require "resty.uuid"
+    local uuid = resty_uuid:generate()
+    ngx.say("UUID: ", uuid)
 
 Author
 ======

lib/resty/uuid.lua

@@ -0,0 +1,31 @@
+module("resty.uuid", package.seeall)
+
+_VERSION = '0.01'
+
+local ffi = require "ffi"
+local ffi_new = ffi.new
+local ffi_str = ffi.string
+
+ffi.cdef[[
+    typedef unsigned char uuid_t[16];
+    void uuid_generate(uuid_t out);
+    void uuid_unparse(const uuid_t uu, char *out);
+]]
+
+local libuuid = ffi.load("libuuid")
+
+function generate()
+    if libuuid then
+        local uuid   = ffi_new("uuid_t")
+        local result = ffi_new("char[36]")
+        libuuid.uuid_generate(uuid)
+        libuuid.uuid_unparse(uuid, result)
+        return ffi_str(result)
+    end
+end
+
+-- to prevent use of casual module global variables
+getmetatable(resty.uuid).__newindex = function (table, key, val)
+    error('attempt to write to undeclared variable "' .. key .. '": '
+            .. debug.traceback())
+end