improvement: queue or cancel previous connect request

metals/src/main/scala/scala/meta/internal/bsp/BspConfigGenerator.scala

@@ -10,6 +10,7 @@ import scala.util.control.NonFatal
 import scala.meta.internal.bsp.BspConfigGenerationStatus._
 import scala.meta.internal.builds.BuildServerProvider
 import scala.meta.internal.builds.ShellRunner
+import scala.meta.internal.metals.CancelableFuture
 import scala.meta.internal.metals.Directories
 import scala.meta.internal.metals.Messages.BspProvider
 import scala.meta.internal.metals.MetalsEnrichments._
@@ -31,7 +32,7 @@ final class BspConfigGenerator(
   def runUnconditionally(
       buildTool: BuildServerProvider,
       args: List[String],
-  ): Future[BspConfigGenerationStatus] =
+  ): CancelableFuture[BspConfigGenerationStatus] =
     shellRunner
       .run(
         s"${buildTool.buildServerName} bspConfig",

metals/src/main/scala/scala/meta/internal/bsp/BspConnector.scala

@@ -159,6 +159,7 @@ class BspConnector(
                   args => bspConfigGenerator.runUnconditionally(bsp, args),
                   statusBar,
                 )
+                .future
                 .flatMap { _ =>
                   connect(
                     projectRoot,

metals/src/main/scala/scala/meta/internal/bsp/BuildChange.scala

@@ -12,4 +12,5 @@ object BuildChange {
   case object Failed extends BuildChange
   case object Reconnected extends BuildChange
   case object Reloaded extends BuildChange
+  case object Cancelled extends BuildChange
 }

metals/src/main/scala/scala/meta/internal/builds/BloopInstall.scala

@@ -1,14 +1,18 @@
 package scala.meta.internal.builds
 
 import java.util.concurrent.TimeUnit
-import java.util.concurrent.atomic.AtomicBoolean
 
 import scala.concurrent.ExecutionContext
 import scala.concurrent.Future
+import scala.concurrent.Promise
 
 import scala.meta.internal.builds.Digest.Status
 import scala.meta.internal.metals.BuildInfo
+import scala.meta.internal.metals.CancelSwitch
+import scala.meta.internal.metals.CancelableFuture
 import scala.meta.internal.metals.Confirmation
+import scala.meta.internal.metals.Interruptable
+import scala.meta.internal.metals.Interruptable._
 import scala.meta.internal.metals.Messages._
 import scala.meta.internal.metals.MetalsEnrichments._
 import scala.meta.internal.metals.Tables
@@ -37,40 +41,30 @@ final class BloopInstall(
   override def toString: String = s"BloopInstall($workspace)"
 
   def runUnconditionally(
-      buildTool: BloopInstallProvider,
-      isImportInProcess: AtomicBoolean,
-  ): Future[WorkspaceLoadedStatus] = {
-    if (isImportInProcess.compareAndSet(false, true)) {
-      buildTool.bloopInstall(
-        workspace,
-        args => {
-          scribe.info(s"running '${args.mkString(" ")}'")
-          val process =
-            runArgumentsUnconditionally(buildTool, args, userConfig().javaHome)
-          process.foreach { e =>
-            if (e.isFailed) {
-              // Record the exact command that failed to help troubleshooting.
-              scribe.error(s"$buildTool command failed: ${args.mkString(" ")}")
-            }
+      buildTool: BloopInstallProvider
+  ): CancelableFuture[WorkspaceLoadedStatus] = {
+    buildTool.bloopInstall(
+      workspace,
+      args => {
+        scribe.info(s"running '${args.mkString(" ")}'")
+        val process =
+          runArgumentsUnconditionally(buildTool, args, userConfig().javaHome)
+        process.future.foreach { e =>
+          if (e.isFailed) {
+            // Record the exact command that failed to help troubleshooting.
+            scribe.error(s"$buildTool command failed: ${args.mkString(" ")}")
           }
-          process.onComplete(_ => isImportInProcess.set(false))
-          process
-        },
-      )
-    } else {
-      Future
-        .successful {
-          languageClient.showMessage(ImportAlreadyRunning)
-          WorkspaceLoadedStatus.Dismissed
         }
-    }
+        process
+      },
+    )
   }
 
   private def runArgumentsUnconditionally(
       buildTool: BloopInstallProvider,
       args: List[String],
       javaHome: Option[String],
-  ): Future[WorkspaceLoadedStatus] = {
+  ): CancelableFuture[WorkspaceLoadedStatus] = {
     persistChecksumStatus(Status.Started, buildTool)
     val processFuture = shellRunner
       .run(
@@ -92,7 +86,7 @@ final class BloopInstall(
         case ExitCodes.Cancel => WorkspaceLoadedStatus.Cancelled
         case result => WorkspaceLoadedStatus.Failed(result)
       }
-    processFuture.foreach { result =>
+    processFuture.future.foreach { result =>
       try result.toChecksumStatus.foreach(persistChecksumStatus(_, buildTool))
       catch {
         case _: InterruptedException =>
@@ -123,36 +117,36 @@ final class BloopInstall(
   def runIfApproved(
       buildTool: BloopInstallProvider,
       digest: String,
-      isImportInProcess: AtomicBoolean,
-  ): Future[WorkspaceLoadedStatus] =
+  ): CancelableFuture[WorkspaceLoadedStatus] =
     synchronized {
       oldInstallResult(digest) match {
         case Some(result)
             if result != WorkspaceLoadedStatus.Duplicate(Status.Requested) =>
           scribe.info(s"skipping build import with status '${result.name}'")
-          Future.successful(result)
+          CancelableFuture.successful(result)
         case _ =>
           if (userConfig().shouldAutoImportNewProject) {
-            runUnconditionally(buildTool, isImportInProcess)
+            runUnconditionally(buildTool)
           } else {
             scribe.debug("Awaiting user response...")
-            for {
+            implicit val cancelSwitch = CancelSwitch(Promise[Unit]())
+            (for {
               userResponse <- requestImport(
                 buildTools,
                 buildTool,
                 languageClient,
                 digest,
-              )
+              ).withInterrupt
               installResult <- {
                 if (userResponse.isYes) {
-                  runUnconditionally(buildTool, isImportInProcess)
+                  runUnconditionally(buildTool).withInterrupt
                 } else {
                   // Don't spam the user with requests during rapid build changes.
                   notification.dismiss(2, TimeUnit.MINUTES)
-                  Future.successful(WorkspaceLoadedStatus.Rejected)
+                  Interruptable.successful(WorkspaceLoadedStatus.Rejected)
                 }
               }
-            } yield installResult
+            } yield installResult).toCancellable
           }
       }
     }

metals/src/main/scala/scala/meta/internal/builds/BloopInstallProvider.scala

@@ -2,8 +2,7 @@ package scala.meta.internal.builds
 import java.io.IOException
 import java.nio.file.Files
 
-import scala.concurrent.Future
-
+import scala.meta.internal.metals.CancelableFuture
 import scala.meta.internal.metals.MetalsEnrichments._
 import scala.meta.io.AbsolutePath
 
@@ -18,8 +17,8 @@ trait BloopInstallProvider extends BuildTool {
    */
   def bloopInstall(
       workspace: AbsolutePath,
-      systemProcess: List[String] => Future[WorkspaceLoadedStatus],
-  ): Future[WorkspaceLoadedStatus] = {
+      systemProcess: List[String] => CancelableFuture[WorkspaceLoadedStatus],
+  ): CancelableFuture[WorkspaceLoadedStatus] = {
     cleanupStaleConfig()
     systemProcess(bloopInstallArgs(workspace))
   }

metals/src/main/scala/scala/meta/internal/builds/BuildServerProvider.scala

@@ -4,6 +4,7 @@ import scala.annotation.nowarn
 import scala.concurrent.Future
 
 import scala.meta.internal.bsp.BspConfigGenerationStatus._
+import scala.meta.internal.metals.CancelableFuture
 import scala.meta.internal.metals.Messages
 import scala.meta.internal.metals.StatusBar
 import scala.meta.io.AbsolutePath
@@ -20,12 +21,16 @@ trait BuildServerProvider extends BuildTool {
   @nowarn("msg=parameter statusBar in method generateBspConfig is never used")
   def generateBspConfig(
       workspace: AbsolutePath,
-      systemProcess: List[String] => Future[BspConfigGenerationStatus],
+      systemProcess: List[String] => CancelableFuture[
+        BspConfigGenerationStatus
+      ],
       statusBar: StatusBar,
-  ): Future[BspConfigGenerationStatus] =
+  ): CancelableFuture[BspConfigGenerationStatus] =
     createBspFileArgs(workspace).map(systemProcess).getOrElse {
-      Future.successful(
-        Failed(Right(Messages.NoBspSupport.toString()))
+      CancelableFuture(
+        Future.successful(
+          Failed(Right(Messages.NoBspSupport.toString()))
+        )
       )
     }
 

metals/src/main/scala/scala/meta/internal/builds/NewProjectProvider.scala

@@ -134,6 +134,7 @@ class NewProjectProvider(
         javaHome,
         javaOptsMap = javaOpts,
       )
+      .future
       .flatMap {
         case ExitCodes.Success =>
           askForWindow(projectPath)

metals/src/main/scala/scala/meta/internal/builds/SbtBuildTool.scala

@@ -77,7 +77,7 @@ case class SbtBuildTool(
 
   def shutdownBspServer(
       shellRunner: ShellRunner
-  ): Future[Int] = {
+  ): CancelableFuture[Int] = {
     val shutdownArgs =
       composeArgs(List("--client", "shutdown"), projectRoot, projectRoot.toNIO)
     scribe.info(s"running ${shutdownArgs.mkString(" ")}")
@@ -242,7 +242,7 @@ case class SbtBuildTool(
               if (promise.isCompleted) {
                 // executes when user chooses `restart` after the timeout
                 restartSbtBuildServer()
-              } else shutdownBspServer(shellRunner).ignoreValue
+              } else shutdownBspServer(shellRunner).future.ignoreValue
             case _ =>
               promise.trySuccess(())
               Future.successful(())

metals/src/main/scala/scala/meta/internal/builds/ScalaCliBuildTool.scala

@@ -2,10 +2,9 @@ package scala.meta.internal.builds
 
 import java.security.MessageDigest
 
-import scala.concurrent.Future
-
 import scala.meta.internal.bsp.BspConfigGenerationStatus._
 import scala.meta.internal.metals.BuildInfo
+import scala.meta.internal.metals.CancelableFuture
 import scala.meta.internal.metals.Directories
 import scala.meta.internal.metals.MetalsEnrichments._
 import scala.meta.internal.metals.StatusBar
@@ -26,9 +25,11 @@ case class ScalaCliBuildTool(
 
   override def generateBspConfig(
       workspace: AbsolutePath,
-      systemProcess: List[String] => Future[BspConfigGenerationStatus],
+      systemProcess: List[String] => CancelableFuture[
+        BspConfigGenerationStatus
+      ],
       statusBar: StatusBar,
-  ): Future[BspConfigGenerationStatus] =
+  ): CancelableFuture[BspConfigGenerationStatus] =
     createBspFileArgs(workspace).map(systemProcess).getOrElse {
       // fallback to creating `.bsp/scala-cli.json` that starts JVM launcher
       val bspConfig =
@@ -37,7 +38,7 @@ case class ScalaCliBuildTool(
       bspConfig.writeText(
         ScalaCli.scalaCliBspJsonContent(projectRoot = projectRoot.toString())
       )
-      Future.successful(Generated)
+      CancelableFuture.successful(Generated)
     }
 
   override def createBspFileArgs(

metals/src/main/scala/scala/meta/internal/builds/ShellRunner.scala

@@ -4,13 +4,13 @@ import java.io.File
 
 import scala.concurrent.Await
 import scala.concurrent.ExecutionContext
-import scala.concurrent.Future
 import scala.concurrent.Promise
 import scala.concurrent.duration.DurationInt
 import scala.language.postfixOps
 import scala.util.Properties
 
 import scala.meta.internal.metals.Cancelable
+import scala.meta.internal.metals.CancelableFuture
 import scala.meta.internal.metals.JavaBinary
 import scala.meta.internal.metals.JdkSources
 import scala.meta.internal.metals.MetalsEnrichments._
@@ -45,7 +45,7 @@ class ShellRunner(time: Time, workDoneProvider: WorkDoneProgress)(implicit
       processErr: String => Unit = scribe.error(_),
       propagateError: Boolean = false,
       javaOptsMap: Map[String, String] = Map.empty,
-  ): Future[Int] = {
+  ): CancelableFuture[Int] = {
 
     val classpathSeparator = if (Properties.isWin) ";" else ":"
     val classpath = Fetch
@@ -92,7 +92,7 @@ class ShellRunner(time: Time, workDoneProvider: WorkDoneProgress)(implicit
       processErr: String => Unit = scribe.error(_),
       propagateError: Boolean = false,
       logInfo: Boolean = true,
-  ): Future[Int] = {
+  ): CancelableFuture[Int] = {
     val elapsed = new Timer(time)
     val env = additionalEnv ++ JdkSources.envVariables(javaHome)
     val ps = SystemProcess.run(
@@ -125,7 +125,7 @@ class ShellRunner(time: Time, workDoneProvider: WorkDoneProgress)(implicit
       result.trySuccess(code)
     }
     result.future.onComplete(_ => cancelables.remove(newCancelable))
-    result.future
+    CancelableFuture(result.future, newCancelable)
   }
 
 }

metals/src/main/scala/scala/meta/internal/metals/CancelableFuture.scala

@@ -4,7 +4,7 @@ import scala.concurrent.ExecutionContext
 import scala.concurrent.Future
 import scala.util.Try
 
-case class CancelableFuture[T](
+case class CancelableFuture[+T](
     future: Future[T],
     cancelable: Cancelable = Cancelable.empty,
 ) extends Cancelable {