onkarkore / kvstore Goto Github PK

The Key-Value store

1. Copy "/usr/lib/go/src/pkg/github.com/onkarkore/kvstore/createfile.py" to current working directory.

2. Start the server by running following command

    go run keyvalueserver.go 
   
    OR
   
    by executing kvstore binary file
   

3. Then client can connect to the server by using following command

   telnet < ip address of server > < port number(here it is 1204) >

   e.g telnet localhost 1204

4. Multiple clients can allow to connect by using same command

5. Server is stopped by typing 'EXIT' on server side

6. Operations performed on client side

   • Type 'help' and press enter to see all commands.

   • Store key-value pair by using follwing command (space is not allowed in key)

     set < key > < value >

   • Update key-value pair by using follwing command

     set < key > < value >

   • Retrive value by using follwing command

     get < key >

   • Delete key-value pair by using follwing command

     delete < key >

   • Rename key by using follwing command

     rename < oldkey > < newkey >

   • List all keys by using follwing command

     list

7. Operation performed on server side

   • Type 'EXIT' to stop server and close all connections with client
   • Main function creates log file "log.txt"
   • Logging is done at every step to recover key-value pairs after failure (failure like if we updated or deleted key-value pair then it will only affect map but "input.txt" contain old data. At the same time if server crashed or power failure cause server to stop abnormally then our data become inconsistent.)
   • Log file contains information like
     • date and time when client connect and disconnect
     • operations performed by clients with date and time
     • connection errors, io errors are also logged
   • Read "input.txt" file and load all key-value pairs in map when server starts
   • Execute "createfile.py" python script to check whether server stoped normally by pressing 'EXIT' command last time. If did not stopped normally then "input.txt" file is recovered by using "log.txt" file.
   • If new key-value pair is added then write immediately to "input.txt" file
   • If key-value pair is updated or deleted then only map will updated. The updated key-value pair in map will be stored in file "input.txt" after pressing 'EXIT'

References -

1. Logging - http://www.goinggo.net/2013/11/using-log-package-in-go.html

2. Main idea - https://github.com/grahamking/Key-Value-Polyglot/blob/master/memg.go

3. Read file - http://rosettacode.org/wiki/Read_a_file_line_by_line#Go

4. Append data in file - http://stackoverflow.com/questions/7151261/append-to-a-file-in-go