philpoore / RecentlyVisited

Recently Visited Service

Recently Visited Service

A simple Recently Visited Service written in c++.

For each user, stores the last 100 recently visisted products / pages.

For each visit, the unix timestamp in nanoseconds of the visit is stored.

A Linked Hash Map is used for Least Recently Used data structure, giving following time complexity:

- get: list recently visited products for user O(1)
- set: user visits product O(1)

Only the last 100 unique products are stored. If a user revisits a product in the LRU, it timestamp is updated and moved to the beggining of the list.

Communication with service is done via tcp protocol. The following binary commands are available:

set

Sets a recently visited product for a given user_id.

• user_id's can be any string
• product_id's are 64 bit unsigned ints

set {user_id} {product_id}

Example:

Set user 123123 visiting product 5555.

echo "set 123123 5555" | nc 127.0.0.1 8091 -q0
# ok

get

Gets the recent visited list for a given user.

get {user_id}

Example:

echo "get 123123" | nc 127.0.0.1 8091
# 5555

quit

Terminate the connection.

Build

make

Run

Will start the server on port 8091.

./RecentlyVisited