Writing a cache Server
Creating an in memory database server in python
Commands
- GET
- SET
- DELETE
- FLUSH
- MGET ...
- MSET ...
Supported data types
- String and Binary Data
- Numbers
- NULL
- Arrays (Which may be nested)
- Dictionaries (May also be nested)
- Error messages
Additionally
- gevent: Handles multiple clients asynchronously
Wire Protocol
The Redis protocol uses a request/response pattern with the clients. Responses from the server will use the first byte to indicate data-type, followed by the data, terminated by a carriage-return/line-feed.
| Data-type | Prefix | Structure | Example |
|---|---|---|---|
| String | + | +{string data}\r\n | +this is a string\r\n |
| Error | - | -{error essage}\r\n | -ERR unknown command "FLUHS"\r\n |
| Interger | : | :{the number}\r\n | :1337\r\n |
| Binary | $ | ${number of bytes}\r\n{data}\r\n | $6\r\nfoobar\r\n |
| Array | * | *{number of elements}\r\n{0 or more of above}\r\n | ```*3\r\n+simple string\r\n:12345\r\n$7\r\ntesting\r\n |
| Dict | % | %{number of keys}\r\n{0 or more of above}\r\n | Example |
| NULL | $ | $-1\r\n{string of length -1} | $-1\r\n |
Additional reading
Source: Write your own Redis (Written for python2.7)