Use IO monad when starting servers

Change-Id: I3e97161535fc721dda6109c4cb5f23a1db0afde3
Signed-off-by: Piotr Jaszczyk <piotr.jaszczyk@nokia.com>
Issue-ID: DCAEGEN2-601

2 files changed, 32 insertions, 25 deletions

diff --git a/hv-collector-main/src/main/kotlin/org/onap/dcae/collectors/veshv/main/main.kt b/hv-collector-main/src/main/kotlin/org/onap/dcae/collectors/veshv/main/main.kt
index d1c3b4a7..f5efab2b 100644
--- a/hv-collector-main/src/main/kotlin/org/onap/dcae/collectors/veshv/main/main.kt
+++ b/hv-collector-main/src/main/kotlin/org/onap/dcae/collectors/veshv/main/main.kt
@@ -19,34 +19,38 @@
  */
 package org.onap.dcae.collectors.veshv.main
 
-import arrow.core.flatMap
 import org.onap.dcae.collectors.veshv.boundary.Server
+import org.onap.dcae.collectors.veshv.boundary.ServerHandle
 import org.onap.dcae.collectors.veshv.factory.CollectorFactory
 import org.onap.dcae.collectors.veshv.factory.ServerFactory
 import org.onap.dcae.collectors.veshv.impl.adapters.AdapterFactory
 import org.onap.dcae.collectors.veshv.model.ServerConfiguration
-import org.onap.dcae.collectors.veshv.utils.commandline.handleErrorsInMain
+import org.onap.dcae.collectors.veshv.utils.arrow.ExitFailure
+import org.onap.dcae.collectors.veshv.utils.arrow.unsafeRunEitherSync
+import org.onap.dcae.collectors.veshv.utils.arrow.void
+import org.onap.dcae.collectors.veshv.utils.commandline.handleWrongArgumentErrorCurried
 import org.onap.dcae.collectors.veshv.utils.logging.Logger
 
 private val logger = Logger("org.onap.dcae.collectors.veshv.main")
 private const val PROGRAM_NAME = "java org.onap.dcae.collectors.veshv.main.MainKt"
 
-fun main(args: Array<String>) {
-    ArgBasedServerConfiguration().parse(args)
-            .toEither()
-            .map(::createServer)
-            .map(Server::start)
-            .flatMap { it.attempt().unsafeRunSync() }
-            .fold(
-                    { ex ->
-                        handleErrorsInMain(ex, PROGRAM_NAME, logger)
-                    },
-                    { handle ->
-                        logger.info("Server started. Listening on ${handle.host}:${handle.port}")
-                        handle.await().unsafeRunSync()
-                    }
-            )
-}
+fun main(args: Array<String>) =
+        ArgBasedServerConfiguration().parse(args)
+                .mapLeft(handleWrongArgumentErrorCurried(PROGRAM_NAME))
+                .map(::createServer)
+                .map {
+                    it.start()
+                            .map(::logServerStarted)
+                            .flatMap(ServerHandle::await)
+                }
+                .unsafeRunEitherSync(
+                        { ex ->
+                            logger.error("Failed to start a server", ex)
+                            ExitFailure(1)
+                        },
+                        { logger.info("Gentle shutdown") }
+                )
+
 
 private fun createServer(config: ServerConfiguration): Server {
     val sink = if (config.dummyMode) AdapterFactory.loggingSink() else AdapterFactory.kafkaSink()
@@ -60,3 +64,7 @@ private fun createServer(config: ServerConfiguration): Server {
     return ServerFactory.createNettyTcpServer(config, collectorProvider)
 }
 
+private fun logServerStarted(handle: ServerHandle): ServerHandle {
+    logger.info("HighVolume VES Collector is up and listening on ${handle.host}:${handle.port}")
+    return handle
+}
diff --git a/hv-collector-main/src/test/kotlin/org/onap/dcae/collectors/veshv/main/ArgBasedServerConfigurationTest.kt b/hv-collector-main/src/test/kotlin/org/onap/dcae/collectors/veshv/main/ArgBasedServerConfigurationTest.kt
index a14801da..2c49cf98 100644
--- a/hv-collector-main/src/test/kotlin/org/onap/dcae/collectors/veshv/main/ArgBasedServerConfigurationTest.kt
+++ b/hv-collector-main/src/test/kotlin/org/onap/dcae/collectors/veshv/main/ArgBasedServerConfigurationTest.kt
@@ -21,6 +21,7 @@ package org.onap.dcae.collectors.veshv.main
 
 import arrow.core.Failure
 import arrow.core.Success
+import arrow.core.identity
 import org.assertj.core.api.Assertions.assertThat
 import org.jetbrains.spek.api.Spek
 import org.jetbrains.spek.api.dsl.describe
@@ -49,13 +50,11 @@ object ArgBasedServerConfigurationTest : Spek({
         cut = ArgBasedServerConfiguration()
     }
 
-    fun parse(vararg cmdLine: String): ServerConfiguration {
-        val result = cut.parse(cmdLine)
-        return when (result) {
-            is Success -> result.value
-            is Failure -> throw AssertionError("Parsing result should be present")
-        }
-    }
+    fun parse(vararg cmdLine: String): ServerConfiguration =
+            cut.parse(cmdLine).fold(
+                    {throw AssertionError("Parsing result should be present")},
+                    ::identity
+            )
 
     describe("parsing arguments") {
         given("all parameters are present in the long form") {