In-memory redis database implementation in Go
- Write parsers to handle RESP protocol messages
- Handly multiple connections with goroutines
- Use append only files to persist data
SET user jp # The key > string, value serialized
GET user
>> "jp"SET user jp
*3\r\n$3\r\nset\r\n$4\r\nuser\r\n$2\r\njp
---------
*3
$3
set
$4
user
$2
jp*3 indicates that we have an array with a size of 3.
We will read 6 lines.
Each pair of lines represents the type and size of the object,
Second line contains the value of that object.
$ indicates that it is a string with a length of 5. So the next line will contain exactly 5 characters.
Similarly, when we say `GET user`, it returns the same object structure with different values
$2\r\jp\r\n
Ref: RESP: https://redis.io/docs/reference/protocol-spec/ Redis serialization protocol (RESP) is the wire protocol that clients implement
To communicate with the Redis server, Redis clients use a protocol called REdis Serialization Protocol (RESP). While the protocol was designed specifically for Redis, you can use it for other client-server software projects.
RESP can serialize different data types including integers, strings, and arrays. It also features an error-specific type. A client sends a request to the Redis server as an array of strings. The array's contents are the command and its arguments that the server should execute. The server's reply type is command-specific.
RESP is binary-safe and uses prefixed length to transfer bulk data so it does not require processing bulk data transferred from one process to another.
A client connects to a Redis server by creating a TCP connection to its port (the default is 6379) The following table summarizes the RESP data types that Redis supports:
| RESP data type | Minimal protocol version | Category | First byte |
|-------------------|--------------------------|----------|------------|
| Simple strings | RESP2 | Simple | + |
| Simple Errors | RESP2 | Simple | - |
| Integers | RESP2 | Simple | : |
| Bulk strings | RESP2 | Aggregate| $ |
| Arrays | RESP2 | Aggregate| * |
| Nulls | RESP3 | Simple | _ |
| Booleans | RESP3 | Simple | # |
| Doubles | RESP3 | Simple | , |
| Big numbers | RESP3 | Simple | ( |
| Bulk errors | RESP3 | Aggregate| ! |
| Verbatim strings | RESP3 | Aggregate| = |
| Maps | RESP3 | Aggregate| % |
| Sets | RESP3 | Aggregate| ~ |
| Pushes | RESP3 | Aggregate| > |
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