Quickmap - a simple in-memory key-value store

Quickmap is a simple and light weight in-memory key-value data store that can concurrently do operations on its underlying data structure. The type of key and value can be anything of int, float, string, and complex numbers.

For now, it has a server component. The server starts on port 5050 and it listens for GET requests at the localhost:5050/api/v1/exec-command endpoint.

Request body structure

{
	"command": "string"
}

Response body structure

{
	"code": 200,
	"value": null,
	"error": ""
}

The response structure is same for all commands. The value is null for some commands (e.g. SET command). The code is in sync with the response status.

One thing to note that the value can be of integer type, string type or float type.

Available Commands

SET

Usage: SET <key> <value> [EX <expiry>] [<condition>]

Set the Key Value pair with optional expiry duration and condition.

The supported types for <key> and <value> are string, float, int,
and complex numbers.

<expiry> is an optional integer value which denotes the duration in
second after which the key-value pair in the store will expire.

<condition> is an optional field used to control the SET behaviour.
Two supported values are NX and XX.
NX - Only set the key if it does not already exist
XX - Only set the key if it already exists

Example requests:

curl -X GET "127.0.0.1:5050/api/v1/exec-command" \
	-H "Content-type: application/json" \
	-d '{"command": "SET test 20.5 EX 60 NX"}'

Response:

{
	"code":201,
	"value":null,
	"error":""
}

GET

Usage: GET <key>

Get the value associated with the specified key.

The supported types for <key> are string, float, int, and
complex numbers.

Example Request:

curl -X GET "127.0.0.1:5050/api/v1/exec-command" \
	-H "Content-type: application/json" \
	-d '{"command": "GET test"}'

Response:

{
	"code":200,
	"value":20.5,
	"error":""
}

QPUSH

Usage: QPUSH <key> <value...>

Creates a queue if not already created with the <key> and
appends values to it.

<key> - Name of the queue to write to.
<value...> - Variadic input that receives multiple values separated by space.

Example Request:

curl -X GET "127.0.0.1:5050/api/v1/exec-command" \
	-H "Content-type: application/json" \
	-d '{"command": "QPUSH test 12 10 23 22 false 4.5"}

Example Request:

{
	"code":201,
	"value":null,
	"error":""
}

QPOP

Usage: QPOP <key>

Returns the last inserted value from the queue with the <key>.

Example Request:

curl -X GET "127.0.0.1:5050/api/v1/exec-command" \ 
	-H "Content-type: application/json" \
	-d '{"command": "QPOP test "}

Example Response:

{
	"code":200,
	"value":4.5,
	"err": ""
}

BQPOP

Usage: BQPOP <key> <timeout>

[Experimental] Blocking queue read operation that blocks the thread
until a value is read from the queue.

The command will fail if multiple clients try to read from the queue
at the same time.

<key> - Name of the queue to read from.
<timeout> - The duration in seconds to wait until a value is read from
the queue. The argument must be interpreted as a double value. A value
of 0 immediately returns a value from the queue without blocking.

Example Request:

curl -X GET "127.0.0.1:5050/api/v1/exec-command" \
	-H "Content-type: application/json" \
	-d '{"command": "BQPOP test 10.5"}

Request:

{
	"code":200,
	"value":4.5,
	"err": ""
}

Note that the command name is case-sensitive and all the commands are required to be in capital letter. Otherwise it will return unknown command error.

Future Improvements

Although this is a in-memory key-value store, it is far behind the standard stores in terms of efficieny, optimization and scaling (e.g. redis, Dgraph's Ristretto). This is the reason I put the endpoint under api/v1. I will try to match this repository to the standard ones.

Currently the project doesn't have any unit tests. So I have to add tests also ;)