Awesome

Description

An assignment done for some job interview and slightly refactored since then.

It reads the input file containing log entries stored in JSON format (JsonLogRepository class). Then it processes them calculating duration for the matched logs (DefaultLogHandle class) and sets alert if applicable (FlagEventStrategy.LONG_EVENT class). Finally the processed logs are stored in the database (JdbcEventRepository class).

It features object-oriented design, clean code, hexagonal architecture and prioritize the Single Responsibility Principle.

Pre-requirements:

• Java 8+
• Gradle build system

Usage

gradlew run --args="INPUT_FILE [DATABASE_NAME]"

Examples:

• gradlew run --args="samplelogfile.txt"
• gradlew run --args="samplelogfile.txt sampledb"

Design Considerations

• The use of jdbc batch support has improved the program execution time. My performance tests have showed the decrease of execution time (for my sample data) from 83 seconds to 52 seconds.
• The dedicated thread for processing and storing the parsed logs has improved the execution time by 10 seconds compared to single-thread solution (in hardware setup with external USB hard drive on which the input file was located). The thread support is implemented in the ThreadedLogHandle class utilizing the Decorator design pattern.
• Detecting long events is implemented in dedicated strategy class (FlagEventStrategy.LONG_EVENT) to make it easily findable.
• To deserialize json the GSON library is used (JsonLogAdapter class).
• I had some issues with database (not persisting inserted rows). It turned out that it has to be properly shutdown (some connection url parameter was needed and closing all jdbc connections);
• To support logging the OpsSupport class is used. I like this solution, because all the logging stuff is in a known single (OpsSupport class) place.
• The data classes (Log, Event) are immutable Value Objects. To construct them i use the Builder design pattern.
• To fetch and store data i use the concept of Repositories from DDD. The project repositories are: JsonLogRepository and JdbcEventRepository.
• The infrastructure classes (adapters part of Hexagonal Architecture) are located in the infrastructure package.