In Memory Key Value Store and a Queue Store

This application imitates an in memory key value store with help of golang. It accepts multiple commands such as SET, GET, QPUSH ,QPOP , BQPOP to perform various operations on the store

Running locally

This application can be run locally in 2 ways

1. Using Golang Compiler
2. Using Docker

Requirments

1. Golang How to install Golang ?
2. Docker How to install Docker ?

1. Using Golang Compiler

1. Clone the repository and open the root folder.
2. Run go build -o main
3. To start the application run ./main
4. The server is up and running on port 8080.

2. Using Docker

1. Clone the repository and open the root folder.
2. Run docker build -t inmemorystore . to build the docker image.
3. To start the application run docker run -it -p 8080:8080 --rm --name inmemstore inmemorystore .
4. The server is up and running on port 8080.

Usage

1. Key Value Store

1.1 Pattern:

SET <key> <value> <expiry time>? <condition>?

• <key>:
  The key under which the given value will be stored.

• <value>:
  The value to be stored.

• <expiry time>:
  Specifies the expiry time of the key in seconds.
  Must contain the prefix EX.
  This is an optional field.
  The field must be an integer value.

• <condition>:
  Specifies the decision to take if the key already exists.
  Accepts either NX or XX.

  • NX -- Only set the key if it does not already exist.
  • XX -- Only set the key if it already exists.
    This is an optional field.
    The default behavior will be to upsert the value of the key.

Examples of SET Command:

• SET key_a 2:
  Sets the value 2 in key_a and does not expire.

• SET key_b 3 EX 60:
  Sets the value 3 in key_b and expires in 60 seconds.

• SET key_c 4 EX 60 NX:
  Sets the value 4 in key_c, expires in 60 seconds, and only sets the value if the key does not already exist.

• SET key_d 5 XX:
  Sets the value 5 in key_d, does not expire, and only sets the value if the key already exists.

1.2 Pattern:

GET <key>

• Examples:
  • GET key_a:
    Returns the value stored using the specified key.

2. Queue

2.1 Pattern:

QPUSH <key> <value...>

• <key>:
  Name of the queue to write to.

• <value...>:
  Variadic input that receives multiple values separated by space.

• Examples:

  • QPUSH list_a 1:
    Adds value 1 to the queue named list_a.
  • QPUSH list_a 2 3 4:
    Adds values 2, 3, and 4 to the queue named list_a.

2.2 Pattern:

QPOP <key>

• <Key>:
  Name of the queue.

• Examples:

  • QPUSH list_a 1:
    Returns OK.
  • QPOP list_a:
    Returns 1.
  • QPUSH list_a 1 2:
    Returns OK.
  • QPOP list_a:
    Returns 1.
  • QPOP list_a:
    Returns 2.
  • QPOP list_x:
    Returns null.

3. Blocking Queue

3.1 Pattern:

BQPOP <key> <timeout>

• <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:

  • Scenario 1:

    • QPUSH list_1 a:
      Returns OK.
    • BQPOP list_1 0:
      Returns a.

  • Scenario 2:

    • BQPOP list_1 0:
      Returns null.

  • Scenario 3:

    • BQPOP list_1 10:
      Blocks the request as the queue is empty.
      Returns null after 10 seconds.