improvement: Don't fail during copying

This might cause the compiler to never work again until restart. It seems that the reason might be that one of the files is locked, but this is highly difficult to reproduce.

Connected to scalacenter#1989

Author: tgodzik

backend/src/main/scala/bloop/BloopClassFileManager.scala

@@ -221,7 +221,8 @@ final class BloopClassFileManager(
                 newClassesDir,
                 clientExternalClassesDir.underlying,
                 inputs.ioScheduler,
-                enableCancellation = false
+                enableCancellation = false,
+                inputs.logger
               )
               .map { walked =>
                 readOnlyCopyDenylist.++=(walked.target)
@@ -279,7 +280,8 @@ final class BloopClassFileManager(
                     Paths.get(readOnlyClassesDirPath),
                     clientExternalClassesDir.underlying,
                     inputs.ioScheduler,
-                    enableCancellation = false
+                    enableCancellation = false,
+                    inputs.logger
                   )
                   .map(_ => ())
               }

backend/src/main/scala/bloop/Compiler.scala

@@ -434,7 +434,8 @@ object Compiler {
                   readOnlyClassesDir,
                   clientClassesDir.underlying,
                   compileInputs.ioScheduler,
-                  enableCancellation = false
+                  enableCancellation = false,
+                  compileInputs.logger
                 )
 
                 lastCopy.map { _ =>

backend/src/main/scala/bloop/io/ParallelOps.scala

@@ -22,6 +22,8 @@ import monix.execution.cancelables.CompositeCancelable
 import monix.reactive.Consumer
 import monix.reactive.MulticastStrategy
 import monix.reactive.Observable
+import bloop.logging.Logger
+import scala.util.control.NonFatal
 
 object ParallelOps {
 
@@ -67,7 +69,8 @@ object ParallelOps {
       origin: Path,
       target: Path,
       scheduler: Scheduler,
-      enableCancellation: Boolean
+      enableCancellation: Boolean,
+      logger: Logger
   ): Task[FileWalk] = Task.defer {
     val isCancelled = AtomicBoolean(false)
 
@@ -152,7 +155,7 @@ object ParallelOps {
 
     val copyFileSequentially = Consumer.foreachTask[((Path, BasicFileAttributes), Path)] {
       case ((originFile, originAttrs), targetFile) =>
-        def copy(replaceExisting: Boolean): Unit = {
+        def copy(replaceExisting: Boolean): Unit = try {
           if (replaceExisting) {
             Files.copy(
               originFile,
@@ -168,6 +171,12 @@ object ParallelOps {
             )
           }
           ()
+        } catch {
+          case NonFatal(t) =>
+            logger.report(
+              s"Unexpected error when copying $originFile to $targetFile, you might need to restart the build server.",
+              t
+            )
         }
 
         // It's important that this task is not forked for performance reasons

frontend/src/main/scala/bloop/engine/tasks/CompileTask.scala

@@ -364,7 +364,8 @@ object CompileTask {
           products.readOnlyClassesDir,
           products.newClassesDir,
           ExecutionContext.ioScheduler,
-          enableCancellation = false
+          enableCancellation = false,
+          logger
         )
       }
 

frontend/src/test/scala/bloop/testing/BloopHelpers.scala

@@ -28,6 +28,7 @@ import bloop.util.TestUtil
 
 import monix.execution.CancelableFuture
 import monix.execution.Scheduler
+import bloop.logging.NoopLogger
 
 trait BloopHelpers {
   def loadState(
@@ -87,7 +88,8 @@ trait BloopHelpers {
       baseDir,
       workspace.underlying,
       ExecutionContext.ioScheduler,
-      enableCancellation = false
+      enableCancellation = false,
+      logger
     )
 
     val loadFromNewWorkspace = copyToNewWorkspace.flatMap { _ =>
@@ -305,7 +307,8 @@ trait BloopHelpers {
               classesDir,
               newClassesDir,
               ExecutionContext.ioScheduler,
-              enableCancellation = false
+              enableCancellation = false,
+              NoopLogger
             )
 
             backupDir.map { _ =>