use a logging system example

This commit is contained in:
uleelx 2015-04-07 17:40:55 +08:00
parent 52988e3b02
commit a9e7905ca1

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@ -70,60 +70,65 @@ Quick Look
==========
```lua
-- This is an logging system example using FlatDB
local flatdb = require("flatdb")
-- open a directory as a database
-- 'db' is just a plain empty Lua table that can contain pages
local db = flatdb("./db")
local logger = flatdb("./log")
-- open or create a page named "default"
-- it is also a plain empty Lua table where key-value pair stored in
if not db.default then
db.default = {}
local count = 0
local function common_log(logger, level, message)
local today = os.date("%Y-%m-%d")
if logger[today] == nil then logger[today] = {} end
if logger[today][level] == nil then logger[today][level] = {} end
table.insert(logger[today][level], {
timestamp = os.time(),
level = level,
message = message
})
count = (count+1)%10
if count == 0 then
logger:save()
end
end
-- extend db methods for getting values from 'default' page
flatdb.hack.get = function(db, key)
return db.default[key]
flatdb.hack.debug = function(logger, msg)
common_log(logger, "debug", msg)
end
-- extend db methods for setting values to 'default' page
flatdb.hack.set = function(db, key, value)
db.default[key] = value
flatdb.hack.info = function(logger, msg)
common_log(logger, "info", msg)
end
-- extend db methods for watching new key
flatdb.hack.guard = function(db, f)
setmetatable(db.default, {__newindex = f})
flatdb.hack.warn = function(logger, msg)
common_log(logger, "warn", msg)
end
-- get key-value data from 'default' page
print(db:get("hello"))
flatdb.hack.error = function(logger, msg)
common_log(logger, "error", msg)
end
-- set key-value data to 'default' page
db:set("hello", "world")
flatdb.hack.fatal = function(logger, msg)
common_log(logger, "fatal", msg)
end
-- get key-value data from 'default' page
print(db:get("hello"))
flatdb.hack.find = function(logger, level, date)
if logger[date or os.date("%Y-%m-%d")] then
return logger[date or os.date("%Y-%m-%d")][level]
end
end
-- set guard function
db:guard(function(page, key, value)
print("CREATE KEY permission denied!")
end)
for i = 1, 10 do
logger:debug("This is a debug message.")
logger:info("This is an info message.")
logger:warn("This is a warn message.")
logger:error("This is an error message.")
logger:fatal("This is a fatal message.")
end
-- try creating new key-value pair to 'default' page
db:set("key1", 1)
db:set("key2", 2)
-- update an existing key-value pair
db:set("hello", "bye")
print(db:get("key1")) -- prints nil
print(db:get("key2")) -- prints nil
print(db:get("hello")) -- prints 'bye'
-- store 'default' page to './db/default' file
db:save()
local pp = require("pp")
pp(logger:find("error"))
```
@ -142,6 +147,14 @@ API
- **Tables**
- **flatdb**
When a db is loaded, there is two relations below:
*flatdb[dir] --> db*
*flatdb[db] --> dir*
- **flatdb.hack**
The 'hack' table contains db's methods. There is only one method 'save(db, page)' in it by default.