removed parallelised tasks to ensure determinism of thumbnail creation

Canvas.ts

@@ -67,8 +67,8 @@ export class Canvas {
 
             let hasPaintingAnnotation: boolean = false;
 
-            await Promise.all(customAnnotationFiles.map(async (file: string) => {
-
+            for (const file of customAnnotationFiles) {
+                
                 let directoryName: string = dirname(file);
                 directoryName = directoryName.substr(directoryName.lastIndexOf('/'));
                 const name: string = basename(file, extname(file));
@@ -180,8 +180,8 @@ export class Canvas {
                     annotationJson.body.value = yml.value;
                 }
 
-                canvasJson.items[0].items.push(annotationJson);          
-            }));
+                canvasJson.items[0].items.push(annotationJson); 
+            }
 
             if (!hasPaintingAnnotation) {
                 // for each jpg/pdf/mp4/obj in the canvas directory
@@ -216,8 +216,8 @@ export class Canvas {
 
     private async _annotateFiles(canvasJson: any, files: string[]): Promise<void> {
 
-        await Promise.all(files.map(async (file: string) => {
-            
+        for (let file of files) {
+
             file = Utils.normaliseFilePath(file);
             const extName: string = extname(file);
 
@@ -258,8 +258,7 @@ export class Canvas {
                     annotationJson.body.height = height;
                 }
             }
-
-        }));
+        }
     }
 
     private async _getInfo(): Promise<void> {

Directory.ts

@@ -53,10 +53,16 @@ export class Directory {
             return Utils.compare(a, b);
         });
 
-        await Promise.all(canvases.map(async (canvas: string) => {
+        // example of parallel processing
+        //await Promise.all(canvases.map(async (canvas: string) => { ... });
+
+        // dropped parallel processing in favour of "deterministic" results
+        // also, a lot of tasks in parallel can use too much memory: 
+        // https://blog.lavrton.com/javascript-loops-how-to-handle-async-await-6252dd3c795
+        for (const canvas of canvases) {
             console.log(chalk.green('creating canvas for: ') + canvas);
             this.items.push(new Canvas(canvas, this));
-        }));
+        }
 
         // directories not starting with an underscore
         // these can be child manifests or child collections
@@ -74,14 +80,14 @@ export class Directory {
             return Utils.compare(a, b);
         });
 
-        await Promise.all(directories.map(async (directory: string) => {
+        for (const directory of directories) {
             console.log(chalk.green('creating directory for: ') + directory);
             const name: string = basename(directory);
             const url: string = urljoin(this.url.href, name);
             const newDirectory: Directory = new Directory(directory, url, this.generateThumbs, undefined, this);
             await newDirectory.read();
             this.directories.push(newDirectory);
-        }));
+        }
 
         // if there are no canvas, manifest, or collection directories to read,
         // but there are paintable files in the current directory,
@@ -158,7 +164,7 @@ export class Directory {
 
             // for each child directory, add a collectionitem or manifestitem json boilerplate to items.
 
-            await Promise.all(this.directories.map(async (directory: Directory) => {
+            for (const directory of this.directories) {
                 let itemJson: any;
 
                 if (directory.isCollection) {
@@ -172,8 +178,8 @@ export class Directory {
 
                 await Utils.getThumbnail(itemJson, directory);
 
-                this.indexJson.items.push(itemJson); 
-            }));
+                this.indexJson.items.push(itemJson);
+            }
 
             // check for manifests.yml. if it exists, parse and add to items
             const hasManifestsYml: boolean = await Utils.hasManifestsYml(this.directoryPath);
@@ -228,7 +234,9 @@ export class Directory {
 
             // for each canvas, add canvas json
 
-            await Promise.all(this.items.map(async (canvas: Canvas, index: number) => {
+            let index: number = 0;
+
+            for (const canvas of this.items) {
                 const canvasJson: any = Utils.cloneJson(canvasBoilerplate);
 
                 canvasJson.id = urljoin(this.url.href, 'index.json/canvas', index);
@@ -238,7 +246,9 @@ export class Directory {
 
                 // add canvas to items
                 this.indexJson.items.push(canvasJson);
-            }));
+
+                index++;
+            }
 
             this.indexJson.items.sort((a, b) => {
                 return Utils.compare(a.id, b.id);

Utils.ts

@@ -182,7 +182,6 @@ export class Utils {
             // if debugging: jimp item.getitem is not a function
             // generate thumbnail
             if (json.items && json.items.length && json.items[0].items) {
-                console.log(chalk.green('generating thumbnail for: ') + fp);
                 // find an annotation with a painting motivation of type image.
                 const items: any[] =  json.items[0].items;
 
@@ -214,9 +213,16 @@ export class Utils {
                                 thumb.resize(config.thumbnails.width, Jimp.AUTO);
                                 pathToThumb += image.getExtension();
 
-                                thumb.write(pathToThumb, () => {
-                                    console.log(chalk.green('generated thumbnail for: ') + fp);
-                                });
+                                // a thumbnail may already exist at this path (when generating from a flat collection of images)
+                                const thumbExists: boolean = await Utils.fileExists(pathToThumb);
+
+                                if (!thumbExists) {
+                                    thumb.write(pathToThumb, () => {
+                                        console.log(chalk.green('generated thumbnail for: ') + fp);
+                                    });
+                                } else {
+                                    console.log(chalk.green('found thumbnail for: ') + fp);
+                                }
 
                             } else {
                                 // placeholder img path

package.json

@@ -1,6 +1,6 @@
 {
   "name": "biiif",
-  "version": "0.3.13",
+  "version": "0.3.14",
   "description": "A CLI to build IIIF collections",
   "main": "index.js",
   "repository": {
@@ -9,7 +9,7 @@
   },
   "scripts": {
     "test": "tsc && mocha",
-    "testbuild": "node --nolazy --inspect-brk=5858 -e \"require('./index').build('collection', 'https://edsilv.github.io/biiif-test-manifests/sound-manifest')\""
+    "testbuild": "node --nolazy --inspect-brk=5858 -e \"require('./index').build('collection', 'https://edsilv.github.io/biiif-test-manifests/sort-files-numeric-manifest', true)\""
   },
   "engines": {
     "node": ">=8.9.1",