Use IO monad when starting servers

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

5 files changed, 100 insertions, 32 deletions

diff --git a/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/arrow/core.kt b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/arrow/core.kt
new file mode 100644
index 00000000..39964c1e
--- /dev/null
+++ b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/arrow/core.kt
@@ -0,0 +1,31 @@
+/*
+ * ============LICENSE_START=======================================================
+ * dcaegen2-collectors-veshv
+ * ================================================================================
+ * Copyright (C) 2018 NOKIA
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.collectors.veshv.utils.arrow
+
+import arrow.core.Either
+import arrow.core.identity
+
+/**
+ * @author Piotr Jaszczyk <piotr.jaszczyk@nokia.com>
+ * @since July 2018
+ */
+
+
+fun <A> Either<A, A>.flatten() = fold(::identity, ::identity)
diff --git a/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/arrow/effects.kt b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/arrow/effects.kt
new file mode 100644
index 00000000..e37b0d7d
--- /dev/null
+++ b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/arrow/effects.kt
@@ -0,0 +1,49 @@
+/*
+ * ============LICENSE_START=======================================================
+ * dcaegen2-collectors-veshv
+ * ================================================================================
+ * Copyright (C) 2018 NOKIA
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.dcae.collectors.veshv.utils.arrow
+
+import arrow.core.Either
+import arrow.effects.IO
+import kotlin.system.exitProcess
+
+/**
+ * @author Piotr Jaszczyk <piotr.jaszczyk@nokia.com>
+ * @since June 2018
+ */
+
+sealed class ExitCode {
+    abstract val code: Int
+
+    fun io() = IO {
+        exitProcess(code)
+    }
+}
+
+object ExitSuccess : ExitCode() {
+    override val code = 0
+}
+
+data class ExitFailure(override val code: Int) : ExitCode()
+
+fun Either<IO<Unit>, IO<Unit>>.unsafeRunEitherSync(onError: (Throwable) -> ExitCode, onSuccess: () -> Unit) =
+        flatten().attempt().unsafeRunSync().fold({ onError(it).io().unsafeRunSync() }, { onSuccess() })
+
+
+fun IO<Any>.void() = map { Unit }
diff --git a/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/ArgBasedConfiguration.kt b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/ArgBasedConfiguration.kt
index 34c0e651..d5855caa 100644
--- a/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/ArgBasedConfiguration.kt
+++ b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/ArgBasedConfiguration.kt
@@ -19,6 +19,7 @@
  */
 package org.onap.dcae.collectors.veshv.utils.commandline
 
+import arrow.core.Either
 import arrow.core.Option
 import arrow.core.Try
 import arrow.core.getOrElse
@@ -30,16 +31,18 @@ import java.io.File
 import java.nio.file.Path
 import java.nio.file.Paths
 
-abstract class ArgBasedConfiguration<T>(val parser: CommandLineParser) {
+abstract class ArgBasedConfiguration<T>(private val parser: CommandLineParser) {
     abstract val cmdLineOptionsList: List<CommandLineOption>
 
-    fun parse(args: Array<out String>): Try<T> {
+    fun parse(args: Array<out String>): Either<WrongArgumentError, T> {
         val commandLineOptions = cmdLineOptionsList.map { it.option }.fold(Options(), Options::addOption)
-        return Try {
+        val parseResult = Try {
             parser.parse(commandLineOptions, args)
-        }.recoverWith { ex ->
-            Try.raise<CommandLine>(WrongArgumentException(ex, commandLineOptions))
-        }.map (this::getConfiguration)
+        }
+        return parseResult
+                .toEither()
+                .mapLeft { ex -> WrongArgumentError(ex, commandLineOptions) }
+                .map(this::getConfiguration)
     }
 
     protected abstract fun getConfiguration(cmdLine: CommandLine): T
diff --git a/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/WrongArgumentException.kt b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/WrongArgumentError.kt
index 083d5798..f3bb3146 100644
--- a/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/WrongArgumentException.kt
+++ b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/WrongArgumentError.kt
@@ -23,11 +23,10 @@ import org.apache.commons.cli.HelpFormatter
 import org.apache.commons.cli.Options
 
 
-class WrongArgumentException(
-        message: String,
+data class WrongArgumentError(
+        val message: String,
         private val options: Options,
-        parent: Throwable? = null
-) : Exception(message, parent) {
+        val cause: Throwable? = null) {
 
     constructor(par: Throwable, options: Options) : this(par.message ?: "", options, par)
 
diff --git a/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/extensions.kt b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/extensions.kt
index 23bf1658..718ebf8b 100644
--- a/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/extensions.kt
+++ b/hv-collector-utils/src/main/kotlin/org/onap/dcae/collectors/veshv/utils/commandline/extensions.kt
@@ -19,32 +19,18 @@
  */
 package org.onap.dcae.collectors.veshv.utils.commandline
 
-import arrow.core.Failure
-import org.onap.dcae.collectors.veshv.utils.logging.Logger
-import kotlin.system.exitProcess
+import arrow.effects.IO
+import arrow.syntax.function.curried
+import org.onap.dcae.collectors.veshv.utils.arrow.ExitFailure
 
 /**
  * @author Piotr Jaszczyk <piotr.jaszczyk@nokia.com>
  * @since June 2018
  */
 
-fun handleErrorsInMain(ex: Throwable, programName: String, logger: Logger) {
-    when (ex) {
-        is WrongArgumentException -> {
-            ex.printMessage()
-            ex.printHelp(programName)
-            exitProcess(1)
-        }
+fun handleWrongArgumentError(programName: String, err: WrongArgumentError): IO<Unit> = IO {
+    err.printMessage()
+    err.printHelp(programName)
+}.flatMap { ExitFailure(2).io() }
 
-        else -> {
-            logger.error(ex.localizedMessage)
-            logger.debug("An error occurred when starting VES HV Collector", ex)
-            System.exit(2)
-        }
-    }
-}
-
-
-fun <A> Failure<A>.handleErrorsInMain(programName: String, logger: Logger) {
-    handleErrorsInMain(this.exception, programName, logger)
-}
+val handleWrongArgumentErrorCurried = ::handleWrongArgumentError.curried()