intercom-assignment

How to setup :

mvn clean install
java -jar target/vjsai-intercom-assignmnet-1.0-SNAPSHOT-jar-with-dependencies.jar


Change app.properties for changing path of input and output file

Problem Statement : We have some customer records in a text file (customers.txt) -- one customer per line, JSON lines formatted. We want to invite any customer within 100km of our Dublin office for some food and drinks on us. Write a program that will read the full list of customers and output the names and user ids of matching customers (within 100km), sorted by User ID (ascending).

Office Center : 53.339428, -6.257664

Implementation Phase :

Input :

• Reading the file in the form of stream rather than loading all lines in the memory.

Processing :

• Created a Util to compute the Spherical distance as per the wiki article.
• For demonstration used cache to store the computed distances
• Filtered the records basing upon the distance

Output :

• Write the filtered lines to file.

Design Patterns:

• Created a interface to DataStore
• Designed a DataStore Adapter to abstract away the reading and writing part.
• The idea here of using Adapter pattern is to be able to switch with ease in case you need to read from a diffrent DataStore.
• Created a caching layer to cache the computed distance of the user Id from office center.
• Created a filter which would filter basing upon the distance configured and returns the sorted list of filtered users within the given distance.

TODO :

• Need to implement a TTl Cache like https://github.com/vjsai/mini-kafka/blob/master/mini-kafka-core/mini-kafka-core/src/main/java/com/vjsai/mini/kafka/cache/DataCache.java

Assumptions:

• Like specified each line will have json record.
• Location of the user doesnt change frequently.(Like address of home)

Other Scenarios thought of :

Scenario 1 :

If the size of the input file is pretty huge and the filtered users are of low compared to all users.And filtered users are written to a single file.

Approach :

• We can use a single thread to read lines from file
• These lines can be pushed to Queue (BlockingLinkedQueue).
• A ThreadPool to filter out basing upon the distance from queue.
• The filtered records are pushed to writer thread which only hanldes writing to a file.

Scenario 2:

If the input is from different files and output should be written in different files with filtered entries.

Approach :

• Would use LMAX Disruptor to read multiple files and write multiple files.

  Links : https://www.baeldung.com/lmax-disruptor-concurrency