tildly

tildly, a simple yet efficient url-shortner which gives a unique short url for each request.

Implementation

When an application instance connects to etcd, a new counter range is assigned to it. Say two instance of the application, 'instance-1' and instance-2' connects to etcd, first a million keys is assigned to instance-1 and the next million keys is assigned to instance-2. The hash (or the 'short-url') is generated with a 'counter value' prefixed to the orginal request which increments after each use, by this way each hash is *unique*.

Atomicity

Each counter increment is atomic and no two hashes can share the same 'counter value'. This is achieved using transactions in etcd and by comparing the ModRevision before each increment.

Sample Request

{
    "longUrl": "https://www.gnu.org",
    "exipreAt": 0
}

Running locally

Run multiple instaces of the appliction with the -port flag, the default port is :8080. The replication factor can be modifed in the cassandra.go file.

go run main.go -port=8080
go run main.go -port=8081
go run main.go -port=8082
. ...

To run a multi-member etcd cluster and to test fault tolerance refer this. or run make etcd. To test fault tolerance in Cassandra, simply bring down a node and perform a query in anoter node.

Using Docker

using docker compose:

docker-compose up -d

This spins up the application(port :8080) with an etcd and cassandra cluster.