forked from mtcontrib/colddb
125 lines
3.8 KiB
Markdown
125 lines
3.8 KiB
Markdown
ColdDB
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===========
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ColdDB is a minetest mod that implements a serverless, asynchronous, NoSQL database engine.<br>
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It provides a key or key-value storage system using plain Lua tables, also it can iterate through the keys.<br>
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Usage
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===========
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Copy both *colddb.lua* and *async* files to your minetest mod or game. Copy the code from colddb's init file to your mods init file<br>
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Write this code in your lua file.
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1. create a directory and link it as a database.
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```lua
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coldbase = colddb.Colddb("mydb")
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```
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2. add an extra folder to the directory. every new file will be added to the global tag(folder).
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```lua
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coldbase.add_global_tag("ips")
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```
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3. store key item(this key has no value)
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```lua
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coldbase.set_key("MyKey")
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```
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4. store key-value item
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```lua
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coldbase.set("MyKeyAndValue", "Hello world")
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```
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5. retrieve items (get_key's callback(arg) will return true, false, or nil)
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```lua
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coldbase.get("MyKeyAndValue", nil, function(arg)
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if arg then
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minetest.log(string.format("value:%s", arg))
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end
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end)
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coldbase.get_key("MyKey", nil, function(arg)
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if arg then
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minetest.log("Found key")
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else
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minetest.log("Key not found")
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end
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end)
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```
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6. delete key(file) this function works on both keys and key-value keys.
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```lua
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coldbase.remove("MyKeyAndValue")
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```
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7. if add_to_mem_pool is true(true by default). keys are stored in a weak lua table(memory) it will be removed by the gc if its not in-use. Storing data in memory is to prevent the database from constantly loading up data from files.
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```lua
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coldbase.add_to_mem_pool = true
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```
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8. if indexes is true(false by default). When a key file is created an indexing file stores the key for look-ups. this makes it possible to iterate through keys.
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```lua
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coldbase.indexes = true
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```
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9. only if coldbase.indexes is true. returns the amount of keys that are in the indexing file.
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```lua
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coldbase.get_count()
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```
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10. only if coldbase.indexes is true. iterates through the indexing file(breaks and ends if it reaches the end of the file).
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```lua
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coldbase.iterate_index_table(nil, func_list_keys, nil)
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```
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11. adds a folder which can be used in other functions that have tag_name arg.
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```lua
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coldbase.add_tag("Extra_Folder", {"Extra", "Folder"})
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```
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12. returns the tag name if the tag does not exists it creates one.
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```lua
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coldbase.get_or_add_tag("Extra_Folder", {"Extra", "Folder"})
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```
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13. remove tag by name.
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```lua
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coldbase.remove_tag("Extra_Folder")
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```
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Quick Look
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===========
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```lua
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-- create an directory(watchlist) and link it as a database.
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ip_db = colddb.Colddb("watchlist")
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-- When ever a player join's his/her ip address is recorded to the database by player name.
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minetest.register_on_prejoinplayer(function(name, ip)
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ip_db.set(name, ip, ip_db.get_or_add_tag("ips", "ips"))
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end)
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minetest.register_chatcommand("ip", {
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params = "<player>",
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description = "Get an player's ip address.",
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func = function(name, param)
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-- Get the ip record asynchronously.
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ip_db.get(param, ip_db.get_or_add_tag("ips", "ips"), function(record)
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-- If record is contains data send it to the player.
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if record then
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minetest.chat_send_player(name, string.format("%s:%s", param, record))
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else
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-- No record was found.
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minetest.chat_send_player(name, "Can not find ip record.")
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end
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end)
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end
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})
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minetest.register_chatcommand("clear", {
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params = "<player>",
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description = "Clear out the ip database.",
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func = function(name, param)
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ip_db.remove_tag(ip_db.get_or_add_tag("ips", "ips"))
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minetest.chat_send_player(name, "Ip Database Cleared!")
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end
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})
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```
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Quick Look Notes
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===========
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In the example above we could also create a more complex ip database using tags. Creating tags named after the player then assigning the ip files to them.<br>
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This way we could store many ips associated with the player instead of just one ip.
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License
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===========
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ColdDB is distributed under the LGPLv2.1+ license. |