Add utility function for creating SLF4J loggers, and close unused I/O streams from forked processes.

tools/demobench/src/main/kotlin/net/corda/demobench/DemoBench.kt

@@ -2,6 +2,8 @@ package net.corda.demobench
 
 import javafx.scene.image.Image
 import net.corda.demobench.views.DemoBenchView
+import org.slf4j.Logger
+import org.slf4j.LoggerFactory
 import tornadofx.App
 import tornadofx.addStageIcon
 
@@ -50,3 +52,7 @@ class DemoBench : App(DemoBenchView::class) {
     }
 }
 
+/*
+ * Trivial utility function to create SLF4J Logger.
+ */
+inline fun <reified T: Any> loggerFor(): Logger = LoggerFactory.getLogger(T::class.java)

tools/demobench/src/main/kotlin/net/corda/demobench/model/DBViewer.kt

@@ -1,14 +1,14 @@
 package net.corda.demobench.model
 
+import net.corda.demobench.loggerFor
 import org.h2.server.web.LocalWebServer
 import org.h2.tools.Server
 import org.h2.util.JdbcUtils
-import org.slf4j.LoggerFactory
 import java.util.concurrent.Executors
 import kotlin.reflect.jvm.jvmName
 
 class DBViewer : AutoCloseable {
-    private val log = LoggerFactory.getLogger(DBViewer::class.java)
+    private val log = loggerFor<DBViewer>()
 
     private val webServer: Server
     private val pool = Executors.newCachedThreadPool()

tools/demobench/src/main/kotlin/net/corda/demobench/model/Explorer.kt

@@ -1,10 +1,10 @@
 package net.corda.demobench.model
 
-import org.slf4j.LoggerFactory
+import net.corda.demobench.loggerFor
 import java.util.concurrent.Executors
 
 class Explorer(val explorerController: ExplorerController) : AutoCloseable {
-    private val log = LoggerFactory.getLogger(Explorer::class.java)
+    private val log = loggerFor<Explorer>()
 
     private val executor = Executors.newSingleThreadExecutor()
     private var process: Process? = null
@@ -32,6 +32,11 @@ class Explorer(val explorerController: ExplorerController) : AutoCloseable {
 
         log.info("Launched Node Explorer for '{}'", config.legalName)
 
+        // Close these streams because no-one is using them.
+        safeClose(p.outputStream)
+        safeClose(p.inputStream)
+        safeClose(p.errorStream)
+
         executor.submit {
             val exitValue = p.waitFor()
             process = null
@@ -46,4 +51,12 @@ class Explorer(val explorerController: ExplorerController) : AutoCloseable {
         process?.destroy()
     }
 
+    private fun safeClose(c: AutoCloseable?) {
+        try {
+            c?.close()
+        } catch (e: Exception) {
+            log.error("Failed to close stream: '{}'", e.message)
+        }
+    }
+
 }

tools/demobench/src/main/kotlin/net/corda/demobench/model/WebServer.kt

@@ -1,10 +1,10 @@
 package net.corda.demobench.model
 
-import org.slf4j.LoggerFactory
+import net.corda.demobench.loggerFor
 import java.util.concurrent.Executors
 
 class WebServer(val webServerController: WebServerController) : AutoCloseable {
-    private val log = LoggerFactory.getLogger(WebServer::class.java)
+    private val log = loggerFor<WebServer>()
 
     private val executor = Executors.newSingleThreadExecutor()
     private var process: Process? = null
@@ -23,6 +23,11 @@ class WebServer(val webServerController: WebServerController) : AutoCloseable {
 
         log.info("Launched Web Server for '{}'", config.legalName)
 
+        // Close these streams because no-one is using them.
+        safeClose(p.outputStream)
+        safeClose(p.inputStream)
+        safeClose(p.errorStream)
+
         executor.submit {
             val exitValue = p.waitFor()
             process = null
@@ -37,4 +42,12 @@ class WebServer(val webServerController: WebServerController) : AutoCloseable {
         process?.destroy()
     }
 
+    private fun safeClose(c: AutoCloseable?) {
+        try {
+            c?.close()
+        } catch (e: Exception) {
+            log.error("Failed to close stream: '{}'", e.message)
+        }
+    }
+
 }

tools/demobench/src/main/kotlin/net/corda/demobench/pty/R3Pty.kt

@@ -4,7 +4,7 @@ import com.jediterm.terminal.TtyConnector
 import com.jediterm.terminal.ui.*
 import com.jediterm.terminal.ui.settings.SettingsProvider
 import com.pty4j.PtyProcess
-import org.slf4j.LoggerFactory
+import net.corda.demobench.loggerFor
 
 import java.awt.*
 import java.nio.charset.StandardCharsets.UTF_8
@@ -13,7 +13,7 @@ import java.util.concurrent.Executors
 import java.util.concurrent.TimeUnit
 
 class R3Pty(val name: String, settings: SettingsProvider, dimension: Dimension, val onExit: () -> Unit) : AutoCloseable {
-    private val log = LoggerFactory.getLogger(R3Pty::class.java)
+    private val log = loggerFor<R3Pty>()
 
     private val executor = Executors.newSingleThreadExecutor()
 

tools/demobench/src/main/kotlin/net/corda/demobench/rpc/NodeRPC.kt

@@ -4,12 +4,12 @@ import com.google.common.net.HostAndPort
 import java.util.*
 import java.util.concurrent.TimeUnit.SECONDS
 import net.corda.core.messaging.CordaRPCOps
+import net.corda.demobench.loggerFor
 import net.corda.demobench.model.NodeConfig
 import net.corda.node.services.messaging.CordaRPCClient
-import org.slf4j.LoggerFactory
 
 class NodeRPC(config: NodeConfig, start: () -> Unit, invoke: (CordaRPCOps) -> Unit): AutoCloseable {
-    private val log = LoggerFactory.getLogger(NodeRPC::class.java)
+    private val log = loggerFor<NodeRPC>()
 
     companion object Data {
         private val ONE_SECOND = SECONDS.toMillis(1)

tools/demobench/src/main/kotlin/net/corda/demobench/views/NodeTerminalView.kt

@@ -107,6 +107,12 @@ class NodeTerminalView : Fragment() {
         }
     }
 
+    /*
+     * We only want to run one web server for each node.
+     * So disable the "launch" button when we have
+     * launched the web server and only reenable it when
+     * the web server has exited.
+     */
     fun configureWebButton(config: NodeConfig) {
         launchWebButton.setOnAction {
             launchWebButton.isDisable = true