For task details, check the Backend Code Assignment.pdf file

Time complexity: O(1)

Space complexity: 0(1)

Space estimations:

       // 70 bytes * 120_000 records (max cache size before cleanup) = 8MB
       internal data class StatsRecord(val t: Long, val amount: Long, val orderCount: Int) {

Tech stack:

1. Kotlin 1.3
2. Gradle 5.5
3. Micronaut Framework 1.2 [https://micronaut.io]
4. Junit 5
5. Docker
6. GraalVM Native Image [https://www.graalvm.org/docs/reference-manual/aot-compilation/]

Build local JAR file: ./gradlew shadowJar

After local build's success, build and run with Docker: docker build .

 
   08:35:41.166 [main] INFO  io.micronaut.runtime.Micronaut - Startup completed in 1949ms. Server Running: http://localhost:8080

Set up your IDE to support Micronaut:

1. Intellij IDEA: enable annotations and delegate all build tasks to Gradle
2. Other IDEs: https://docs.micronaut.io/latest/guide/index.html#ideSetup
3. Build, run and continuously rebuild with Gradle: ./gradlew run --continuous and then after changing a kotlin file this restart message should appear:

08:58:47.667 [main] INFO  io.micronaut.runtime.Micronaut - Startup completed in 873ms. Server Running: http://localhost:8080

1. Run tests from IDE and check the output: 08:52:43.653 [Test worker] INFO ebay.tx.stats.TxRepoTest - Population time: 296.4 ms Calculation time: 25.41 ms
2. Run tests with Gradle ./gradlew clean test