use a FixedThreadPool to execute the timetable updates

closes #9

build.gradle

@@ -33,7 +33,7 @@ repositories {
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.1"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.2"
     implementation 'org.jsoup:jsoup:1.12.1'
     implementation 'org.springframework.boot:spring-boot-starter-web'
 

src/main/kotlin/org/mosad/thecitadelofricks/APIController.kt

@@ -39,7 +39,6 @@ import org.springframework.web.bind.annotation.RequestParam
 import org.springframework.web.bind.annotation.RestController
 import java.time.LocalDateTime
 import java.util.*
-import kotlin.collections.ArrayList
 
 @RestController
 class APIController {

src/main/kotlin/org/mosad/thecitadelofricks/controller/CacheController.kt

@@ -33,7 +33,9 @@ import org.mosad.thecitadelofricks.hsoparser.TimetableParser
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 import java.util.*
+import java.util.concurrent.Executors
 import kotlin.collections.ArrayList
+import kotlin.collections.HashSet
 import kotlin.concurrent.scheduleAtFixedRate
 
 class CacheController {
@@ -153,12 +155,8 @@ class CacheController {
      */
     private fun asyncUpdateCourseList() = GlobalScope.launch {
         CourseListParser().getCourseLinks(courseListURL)?.let {
-            courseList =
-                CourseList(
-                    CourseMeta(
-                        System.currentTimeMillis() / 1000,
-                        it.size
-                    ), it
+            courseList = CourseList(
+                CourseMeta(System.currentTimeMillis() / 1000, it.size), it
                 )
         }
 
@@ -175,12 +173,8 @@ class CacheController {
 
         // only update if we get valid data
         if (mensaCurrentWeek != null && mensaNextWeek != null) {
-            mensaMenu =
-                MensaMenu(
-                    MensaMeta(
-                        System.currentTimeMillis() / 1000,
-                        mensaName
-                    ), mensaCurrentWeek, mensaNextWeek
+            mensaMenu = MensaMenu(
+                MensaMeta(System.currentTimeMillis() / 1000, mensaName), mensaCurrentWeek, mensaNextWeek
             )
         }
 
@@ -190,14 +184,27 @@ class CacheController {
     /**
      * this function updates all existing timetables
      * during the update process the old data will be returned for a API request
+     * a FixedThreadPool is used to make parallel requests for faster updates
      */
     private fun asyncUpdateTimetables() = GlobalScope.launch {
+        logger.info("updating ${timetableList.size} timetables ...")
+
+        // create a new ThreadPool with 5 threads
+        val executor = Executors.newFixedThreadPool(5)
+
+        try {
             timetableList.forEach { timetableCourse ->
-            val updateURL = timetableCourse.meta.link
-            timetableCourse.timetable = TimetableParser().getTimeTable(updateURL)
+                executor.execute {
+                    timetableCourse.timetable = TimetableParser().getTimeTable(timetableCourse.meta.link)
                     timetableCourse.meta.updateTime = System.currentTimeMillis() / 1000
                 }
-        logger.info("updated ${timetableList.size} timetables successful!")
+
+            }
+        } catch (ex: Exception) {
+            logger.error("error while updating the timetables", ex)
+        } finally {
+            executor.shutdown()
+        }
     }
 
     /**
@@ -208,12 +215,8 @@ class CacheController {
         // get all courses on startup
         val jobCourseUpdate = GlobalScope.async {
             CourseListParser().getCourseLinks(courseListURL)?.let {
-                courseList =
-                    CourseList(
-                        CourseMeta(
-                            System.currentTimeMillis() / 1000,
-                            it.size
-                        ), it
+                courseList = CourseList(
+                    CourseMeta(System.currentTimeMillis() / 1000, it.size), it
                 )
             }
         }
@@ -225,12 +228,8 @@ class CacheController {
 
             // only update if we get valid data
             if (mensaCurrentWeek != null && mensaNextWeek != null) {
-                mensaMenu =
-                    MensaMenu(
-                        MensaMeta(
-                            System.currentTimeMillis() / 1000,
-                            mensaName
-                        ), mensaCurrentWeek, mensaNextWeek
+                mensaMenu = MensaMenu(
+                    MensaMeta(System.currentTimeMillis() / 1000, mensaName), mensaCurrentWeek, mensaNextWeek
                 )
             }
         }

src/main/kotlin/org/mosad/thecitadelofricks/controller/StatusController.kt

@@ -59,7 +59,8 @@ class StatusController {
             when (timetableRequests.stream().filter { x -> x.courseName == courseName }.findAny().orElse(null)) {
                 null -> timetableRequests.add(TimetableCounter(courseName, 0))
             }
-            timetableRequests.stream().filter { x ->x.courseName == courseName }.findFirst().ifPresent { x -> x.requests++ }
+            timetableRequests.stream().filter { x -> x.courseName == courseName }.findFirst()
+                .ifPresent { x -> x.requests++ }
 
             // TODO Java 11
 //        timetableRequests.stream().filter { it.courseName == courseName }.findFirst().ifPresentOrElse({