Remove nop command

We use `connection.onClose` to automatically reconnect when the
connection with sbt is closed.

Author: Duhemm

sbt-dotty/src/dotty/tools/sbtplugin/DottyIDEPlugin.scala

@@ -269,9 +269,6 @@ object DottyIDEPlugin extends AutoPlugin {
     Command.process("runCode", state1)
   }
 
-  /** An sbt command that does nothing. We use it to check that sbt server is still alive. */
-  def nopCommand = Command.command("nop")(state => state)
-
   private def projectConfigTask(config: Configuration): Initialize[Task[Option[ProjectConfig]]] = Def.taskDyn {
     if ((sources in config).value.isEmpty) Def.task { None }
     else Def.task {
@@ -307,7 +304,7 @@ object DottyIDEPlugin extends AutoPlugin {
   )
 
   override def buildSettings: Seq[Setting[_]] = Seq(
-    commands ++= Seq(configureIDE, compileForIDE, launchIDE, nopCommand),
+    commands ++= Seq(configureIDE, compileForIDE, launchIDE),
 
     excludeFromIDE := false,
 

vscode-dotty/src/extension.ts

@@ -27,12 +27,6 @@ let sbtProcess: ChildProcess | undefined
 /** The status bar where the show the status of sbt server */
 let sbtStatusBar: vscode.StatusBarItem
 
-/** Interval in ms to check that sbt is alive */
-const sbtCheckIntervalMs = 10 * 1000
-
-/** A command that we use to check that sbt is still alive. */
-export const nopCommand = "nop"
-
 const sbtVersion = "1.2.3"
 const sbtArtifact = `org.scala-sbt:sbt-launch:${sbtVersion}`
 const workspaceRoot = `${vscode.workspace.rootPath}`
@@ -108,8 +102,8 @@ function connectToSbt(coursierPath: string): Thenable<rpc.MessageConnection> {
 
   return offeringToRetry(() => {
     return withSbtInstance(coursierPath).then(connection => {
+      connection.onClose(() => markSbtDownAndReconnect(coursierPath))
       markSbtUp()
-      const interval = setInterval(() => checkSbt(interval, connection, coursierPath), sbtCheckIntervalMs)
       return connection
     })
   }, "Couldn't connect to sbt server (see log for details)")
@@ -130,16 +124,6 @@ function markSbtDownAndReconnect(coursierPath: string) {
   connectToSbt(coursierPath)
 }
 
-/** Check that sbt is alive, try to reconnect if it is dead. */
-function checkSbt(interval: NodeJS.Timer, connection: rpc.MessageConnection, coursierPath: string) {
-  sbtserver.tellSbt(outputChannel, connection, nopCommand)
-  .then(_ => markSbtUp(),
-    _ => {
-      clearInterval(interval)
-      markSbtDownAndReconnect(coursierPath)
-    })
-}
-
 export function deactivate() {
   // If sbt was started by this extension, kill the process.
   // FIXME: This will be a problem for other clients of this server.

vscode-dotty/src/sbt-server.ts

@@ -18,8 +18,6 @@ import * as rpc from 'vscode-jsonrpc'
 
 import * as vscode from 'vscode'
 
-import { nopCommand } from './extension'
-
 /** The result of successful `sbt/exec` call. */
 export interface ExecResult {
   status: string
@@ -70,7 +68,7 @@ export function connectToSbtServer(log: vscode.OutputChannel): Promise<rpc.Messa
       log.appendLine(`<<< [${messageTypeToString(params.type)}] ${params.message}`)
     })
 
-    return tellSbt(log, connection, nopCommand).then(_ => connection)
+    return connection
   })
 }