Spawn new Thread for the export [backend], auto-download when export …

…done [frontend] (#1376)

Also, uses random temp export folders (to prevent concurrency issues when there are multiple simultaneous attempts to export the same project).

Backend.Tests/Controllers/LiftControllerTests.cs

@@ -196,7 +196,7 @@ public async Task TestDeletedWordsExportToLift()
             await _wordService.Update(_projId, wordToUpdate.Id, word);
             await _wordService.DeleteFrontierWord(_projId, wordToDelete.Id);
 
-            _liftController.ExportLiftFile(_projId, UserId).Wait();
+            _liftController.CreateLiftExportThenSignal(_projId, UserId).Wait();
             var result = (FileStreamResult)_liftController.DownloadLiftFile(_projId, UserId).Result;
             Assert.NotNull(result);
 

Backend.Tests/Helper/TimeTests.cs

@@ -16,7 +16,7 @@ public void TestToUtcIso8601()
         }
 
         [Test]
-        public void UtcNowIso8601()
+        public void TestUtcNowIso8601()
         {
             var time = Time.UtcNowIso8601();
             Assert.That(time.Contains("T"));

Backend/Controllers/LiftController.cs

@@ -2,6 +2,7 @@
 using System.IO;
 using System.Linq;
 using System.Runtime.CompilerServices;
+using System.Threading;
 using System.Threading.Tasks;
 using BackendFramework.Helper;
 using BackendFramework.Interfaces;
@@ -208,8 +209,7 @@ public async Task<IActionResult> ExportLiftFile(string projectId)
             return await ExportLiftFile(projectId, userId);
         }
 
-        // These internal methods are extracted for unit testing
-        internal async Task<IActionResult> ExportLiftFile(string projectId, string userId)
+        private async Task<IActionResult> ExportLiftFile(string projectId, string userId)
         {
             if (!await _permissionService.HasProjectPermission(HttpContext, Permission.ImportExport))
             {
@@ -238,35 +238,36 @@ internal async Task<IActionResult> ExportLiftFile(string projectId, string userI
             // Store in-progress status for the export
             _liftService.SetExportInProgress(userId, true);
 
-            try
-            {
-                // Ensure project has words
-                var words = await _wordRepo.GetAllWords(projectId);
-                if (words.Count == 0)
-                {
-                    _liftService.SetExportInProgress(userId, false);
-                    return BadRequest("No words to export.");
-                }
-
-                // Export the data to a zip, read into memory, and delete zip
-                var exportedFilepath = await CreateLiftExport(projectId);
-
-                // Store the temporary path to the exported file for user to download later.
-                _liftService.StoreExport(userId, exportedFilepath);
-                await _notifyService.Clients.All.SendAsync("DownloadReady", userId);
-                return Ok(projectId);
-            }
-            catch
+            // Ensure project has words
+            var words = await _wordRepo.GetAllWords(projectId);
+            if (words.Count == 0)
             {
                 _liftService.SetExportInProgress(userId, false);
-                throw;
+                return BadRequest("No words to export.");
             }
+
+            // Run the task without waiting for completion.
+            // This Task will be scheduled within the exiting Async executor thread pool efficiently.
+            // See: https://stackoverflow.com/a/64614779/1398841
+            _ = Task.Run(() => CreateLiftExportThenSignal(projectId, userId));
+            return Ok(projectId);
+        }
+
+        // These internal methods are extracted for unit testing.
+        internal async Task<bool> CreateLiftExportThenSignal(string projectId, string userId)
+        {
+            // Export the data to a zip, read into memory, and delete zip.
+            var exportedFilepath = await CreateLiftExport(projectId);
+
+            // Store the temporary path to the exported file for user to download later.
+            _liftService.StoreExport(userId, exportedFilepath);
+            await _notifyService.Clients.All.SendAsync(CombineHub.DownloadReady, userId);
+            return true;
         }
 
         internal async Task<string> CreateLiftExport(string projectId)
         {
-            var exportedFilepath = await _liftService.LiftExport(projectId, _wordRepo, _projRepo);
-            return exportedFilepath;
+            return await _liftService.LiftExport(projectId, _wordRepo, _projRepo);
         }
 
         /// <summary> Downloads project data in zip file </summary>

Backend/Helper/CombineHub.cs

@@ -4,5 +4,6 @@ namespace BackendFramework.Helper
 {
     public class CombineHub : Hub
     {
+        public const string DownloadReady = "DownloadReady";
     }
 }

Backend/Helper/FileStorage.cs

@@ -27,69 +27,99 @@ public enum FileType
         [Serializable]
         public class HomeFolderNotFoundException : Exception { }
 
+        /// <summary> Indicates an invalid input id. </summary>
+        [Serializable]
+        public class InvalidIdException : Exception { }
+
         /// <summary>
         /// Generate a path to the file name of an audio file for the Project based on the Word ID.
         /// </summary>
+        /// <exception cref="InvalidIdException"> Throws when id invalid. </exception>
         public static string GenerateAudioFilePathForWord(string projectId, string wordId)
         {
+            if (!Sanitization.SanitizeId(projectId) || !Sanitization.SanitizeId(wordId))
+            {
+                throw new InvalidIdException();
+            }
             return GenerateProjectFilePath(projectId, AudioPathSuffix, wordId, FileType.Audio);
         }
 
         /// <summary>
         /// Generate a path to the file name of an audio file for the Project.
         /// </summary>
+        /// <exception cref="InvalidIdException"> Throws when id invalid. </exception>
         public static string GenerateAudioFilePath(string projectId, string fileName)
         {
+            if (!Sanitization.SanitizeId(projectId))
+            {
+                throw new InvalidIdException();
+            }
             return GenerateProjectFilePath(projectId, AudioPathSuffix, fileName);
         }
 
         /// <summary>
         /// Generate a path to the directory where audio files are stored for the Project.
         /// </summary>
+        /// <exception cref="InvalidIdException"> Throws when id invalid. </exception>
         public static string GenerateAudioFileDirPath(string projectId, bool createDir = true)
         {
+            if (!Sanitization.SanitizeId(projectId))
+            {
+                throw new InvalidIdException();
+            }
             return GenerateProjectDirPath(projectId, AudioPathSuffix, createDir);
         }
 
         /// <summary>
         /// Generate a path to the parent directory where Lift exports are stored.
         /// </summary>
+        /// <exception cref="InvalidIdException"> Throws when id invalid. </exception>
         /// <remarks> This function is not expected to be used often. </remarks>
         public static string GenerateImportExtractedLocationDirPath(string projectId, bool createDir = true)
         {
+            if (!Sanitization.SanitizeId(projectId))
+            {
+                throw new InvalidIdException();
+            }
             return GenerateProjectDirPath(projectId, ImportExtractedLocation, createDir);
         }
 
         /// <summary>
         /// Generate a path to the Lift import folder. This also stores audio files within it.
         /// </summary>
+        /// <exception cref="InvalidIdException"> Throws when id invalid. </exception>
         public static string GenerateLiftImportDirPath(string projectId, bool createDir = true)
         {
+            if (!Sanitization.SanitizeId(projectId))
+            {
+                throw new InvalidIdException();
+            }
             return GenerateProjectDirPath(projectId, LiftImportSuffix, createDir);
         }
 
-        /// <summary>
-        /// Generate a path to the temporary Lift Export folder used during export.
-        /// </summary>
-        /// <remarks> This function may be removed in the future and replaced by temporary directory use. </remarks>
-        public static string GenerateLiftExportDirPath(string projectId, bool createDir = true)
-        {
-            return GenerateProjectDirPath(projectId, ExportDir, createDir);
-        }
-
         /// <summary>
         /// Generate the path to where Avatar images are stored.
         /// </summary>
+        /// <exception cref="InvalidIdException"> Throws when id invalid. </exception>
         public static string GenerateAvatarFilePath(string userId)
         {
+            if (!Sanitization.SanitizeId(userId))
+            {
+                throw new InvalidIdException();
+            }
             return GenerateFilePath(AvatarsDir, userId, FileType.Avatar);
         }
 
         /// <summary>
         /// Get the top-level path to where all files are stored for the project.
         /// </summary>
+        /// <exception cref="InvalidIdException"> Throws when id invalid. </exception>
         public static string GetProjectDir(string projectId)
         {
+            if (!Sanitization.SanitizeId(projectId))
+            {
+                throw new InvalidIdException();
+            }
             return GenerateProjectDirPath(projectId, "", false);
         }
 

Backend/Services/LiftService.cs

@@ -180,15 +180,10 @@ public async Task<string> LiftExport(
             var vernacularBcp47 = proj.VernacularWritingSystem.Bcp47;
 
             // Generate the zip dir.
-            var exportDir = FileStorage.GenerateLiftExportDirPath(projectId);
-            var liftExportDir = Path.Combine(exportDir, "LiftExport");
-            if (Directory.Exists(liftExportDir))
-            {
-                Directory.Delete(liftExportDir, true);
-            }
+            var tempExportDir = FileOperations.GetRandomTempDir();
 
             var projNameAsPath = Sanitization.MakeFriendlyForPath(proj.Name, "Lift");
-            var zipDir = Path.Combine(liftExportDir, projNameAsPath);
+            var zipDir = Path.Combine(tempExportDir, projNameAsPath);
             Directory.CreateDirectory(zipDir);
 
             // Add audio dir inside zip dir.
@@ -341,7 +336,7 @@ public async Task<string> LiftExport(
             }
 
             // Compress everything.
-            var destinationFileName = Path.Combine(exportDir,
+            var destinationFileName = Path.Combine(FileOperations.GetRandomTempDir(),
                 Path.Combine($"LiftExportCompressed-{proj.Id}_{DateTime.Now:yyyy-MM-dd_hh-mm-ss}.zip"));
             var zipParentDir = Path.GetDirectoryName(zipDir);
             if (zipParentDir is null)
@@ -351,7 +346,7 @@ public async Task<string> LiftExport(
             ZipFile.CreateFromDirectory(zipParentDir, destinationFileName);
 
             // Clean up the temporary folder structure that was compressed.
-            Directory.Delete(liftExportDir, true);
+            Directory.Delete(tempExportDir, true);
 
             return destinationFileName;
         }

src/components/App/SignalRHub.tsx

@@ -21,7 +21,7 @@ export default function SignalRHub() {
       connection.stop();
     }
     setConnection(null);
-    if (exportState.status === ExportStatus.InProgress) {
+    if (exportState.status === ExportStatus.Exporting) {
       const newConnection = new HubConnectionBuilder()
         .withUrl(`${baseURL}/hub`)
         .withAutomaticReconnect()
@@ -34,8 +34,7 @@ export default function SignalRHub() {
 
   useEffect(() => {
     if (connection) {
-      // The methodName must match what is used by the Backend in, e.g.,
-      // `_notifyService.Clients.All.SendAsync("DownloadReady", userId);`.
+      // The methodName must match what is in Backend/Helper/CombineHub.cs.
       const methodName = "DownloadReady";
       // The method is what the frontend does upon message receipt.
       const method = (userId: string) => {

src/components/ProjectExport/DownloadButton.tsx

@@ -1,5 +1,5 @@
 import { IconButton, Tooltip } from "@material-ui/core";
-import { Cached, Error as ErrorIcon, GetApp } from "@material-ui/icons";
+import { Cached, Error as ErrorIcon } from "@material-ui/icons";
 import React, { createRef, ReactElement, useEffect, useState } from "react";
 import { Translate } from "react-localize-redux";
 import { useDispatch, useSelector } from "react-redux";
@@ -18,7 +18,10 @@ interface DownloadButtonProps {
   colorSecondary?: boolean;
 }
 
-/** A button to show export status */
+/**
+ * A button to show export status. This automatically initiates a download
+ * when a user's export is done, so there should be exactly one copy of this
+ * component rendered at any given time in the logged-in app. */
 export default function DownloadButton(props: DownloadButtonProps) {
   const exportState = useSelector(
     (state: StoreState) => state.exportProjectState
@@ -36,6 +39,12 @@ export default function DownloadButton(props: DownloadButtonProps) {
     }
   }, [downloadLink, fileUrl]);
 
+  useEffect(() => {
+    if (exportState.status === ExportStatus.Success) {
+      download();
+    } // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [exportState.status]);
+
   function makeExportName(projectName: string) {
     return `${projectName}_${getNowDateTimeString()}.zip`;
   }
@@ -60,10 +69,11 @@ export default function DownloadButton(props: DownloadButtonProps) {
 
   function textId(): string {
     switch (exportState.status) {
-      case ExportStatus.InProgress:
+      case ExportStatus.Exporting:
         return "projectExport.exportInProgress";
       case ExportStatus.Success:
-        return "projectExport.downloadReady";
+      case ExportStatus.Downloading:
+        return "projectExport.downloadInProgress";
       case ExportStatus.Failure:
         return "projectExport.exportFailed";
       default:
@@ -73,10 +83,10 @@ export default function DownloadButton(props: DownloadButtonProps) {
 
   function icon(): ReactElement {
     switch (exportState.status) {
-      case ExportStatus.InProgress:
-        return <Cached />;
+      case ExportStatus.Exporting:
+      case ExportStatus.Downloading:
       case ExportStatus.Success:
-        return <GetApp />;
+        return <Cached />;
       case ExportStatus.Failure:
         return <ErrorIcon />;
       default:
@@ -94,8 +104,6 @@ export default function DownloadButton(props: DownloadButtonProps) {
 
   function iconFunction(): () => void {
     switch (exportState.status) {
-      case ExportStatus.Success:
-        return download;
       case ExportStatus.Failure:
         return reset;
       default: