Hopding#1032 cleanup

JagDadd · Nov 6, 2021 · fbdfbd9 · fbdfbd9
1 parent a1abda4
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Showing 3 changed files with 101 additions and 105 deletions.
diff --git a/src/api/PDFImage.ts b/src/api/PDFImage.ts
@@ -36,7 +36,7 @@ export default class PDFImage implements Embeddable {
   readonly height: number;
 
   private embedder: ImageEmbedder | undefined;
-  private embedderTask: Promise<PDFRef> | undefined;
+  private embedTask: Promise<PDFRef> | undefined;
 
   private constructor(ref: PDFRef, doc: PDFDocument, embedder: ImageEmbedder) {
     assertIs(ref, 'ref', [[PDFRef, 'PDFRef']]);
@@ -125,15 +125,19 @@ export default class PDFImage implements Embeddable {
    * @returns Resolves when the embedding is complete.
    */
   async embed(): Promise<void> {
-    const embedder = this.embedder;
-    if (!embedder) return;
+    if (!this.embedder) return;
 
-    let embedderTask = this.embedderTask;
-    if (!embedderTask) {
-      embedderTask = embedder.embedIntoContext(this.doc.context, this.ref);
-      this.embedderTask = embedderTask;
+    // The image should only be embedded once. If there's a pending embed
+    // operation then wait on it. Otherwise we need to start the embed.
+    if (!this.embedTask) {
+      const { doc, ref } = this;
+      this.embedTask = this.embedder.embedIntoContext(doc.context, ref);
     }
-    await embedderTask;
+    await this.embedTask;
+
+    // We clear `this.embedder` so that the indirectly referenced image data
+    // can be garbage collected, thus avoiding a memory leak.
+    // See https://github.com/Hopding/pdf-lib/pull/1032/files.
     this.embedder = undefined;
   }
 }
diff --git a/tests/api/PDFDocument.spec.ts b/tests/api/PDFDocument.spec.ts
@@ -16,7 +16,8 @@ import {
   ViewerPreferences,
 } from 'src/index';
 
-const examplePngImage = 'data:image/png;base64,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';
+const examplePngImage =
+  'data:image/png;base64,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';
 
 const unencryptedPdfBytes = fs.readFileSync('assets/pdfs/normal.pdf');
 const oldEncryptedPdfBytes1 = fs.readFileSync('assets/pdfs/encrypted_old.pdf');
@@ -434,7 +435,7 @@ describe(`PDFDocument`, () => {
     });
   });
 
-  describe(`addJavaScript method`, () => {
+  describe(`addJavaScript() method`, () => {
     it(`adds the script to the catalog`, async () => {
       const pdfDoc = await PDFDocument.create();
       pdfDoc.addJavaScript(
@@ -473,17 +474,17 @@ describe(`PDFDocument`, () => {
   });
 
   describe(`embedPng() method`, () => {
-    it(`It should still be possible to modify the PDFDocument even if a image has already been embedded`, async () => {
+    it(`does not prevent the PDFDocument from being modified after embedding an image`, async () => {
       const pdfDoc = await PDFDocument.create();
       const pdfPage = pdfDoc.addPage();
 
       const noErrorFunc = async () => {
         const embeddedImage = await pdfDoc.embedPng(examplePngImage);
-        await pdfPage.drawImage(embeddedImage);
+        pdfPage.drawImage(embeddedImage);
         await embeddedImage.embed();
 
         const pdfPage2 = pdfDoc.addPage();
-        await pdfPage2.drawImage(embeddedImage);
+        pdfPage2.drawImage(embeddedImage);
 
         pdfDoc.setTitle('Unit Test');
       };
@@ -493,89 +494,83 @@ describe(`PDFDocument`, () => {
   });
 
   describe(`save() method`, () => {
-
-    it(`The save() function may be called several times with different changes`, async () => {
+    it(`can called multiple times on the same PDFDocument with different changes`, async () => {
       const pdfDoc = await PDFDocument.create();
-      const pdfPage = pdfDoc.addPage();
       const embeddedImage = await pdfDoc.embedPng(examplePngImage);
 
       const noErrorFunc = async () => {
-        await pdfPage.drawImage(embeddedImage);
-        await embeddedImage.embed();
-
-        const pdfPage2 = pdfDoc.addPage();
-        await pdfPage2.drawImage(embeddedImage);
-
-        pdfDoc.setTitle('Unit Test');
+        const page1 = pdfDoc.addPage();
+        page1.drawImage(embeddedImage);
 
         const pdfBytes1 = await pdfDoc.save();
         expect(pdfBytes1.byteLength).toBeGreaterThan(0);
 
-        const pdfPage3 = pdfDoc.addPage();
-        await pdfPage3.drawImage(embeddedImage);
+        const page2 = pdfDoc.addPage();
+        page2.drawImage(embeddedImage);
 
-        pdfDoc.setTitle('Unit Test 2. change');
+        pdfDoc.setTitle('Unit Test');
 
         const pdfBytes2 = await pdfDoc.save();
         expect(pdfBytes2.byteLength).toBeGreaterThan(0);
-        expect(pdfBytes1.byteLength).not.toEqual(pdfBytes2.byteLength);
+        expect(pdfBytes2.byteLength).not.toEqual(pdfBytes1.byteLength);
+
+        const pdfPage3 = pdfDoc.addPage();
+        pdfPage3.drawImage(embeddedImage);
 
-        const pdf1 = await PDFDocument.load(pdfBytes1);
-        expect(pdf1.getTitle()).toEqual('Unit Test');
-        expect(pdf1.getPageCount()).toEqual(2);
+        pdfDoc.setTitle('Unit Test 2. change');
 
-        const pdf2 = await PDFDocument.load(pdfBytes2);
-        expect(pdf2.getTitle()).toEqual('Unit Test 2. change');
-        expect(pdf2.getPageCount()).toEqual(3);
+        const pdfBytes3 = await pdfDoc.save();
+        expect(pdfBytes3.byteLength).toBeGreaterThan(0);
+        expect(pdfBytes3.byteLength).not.toEqual(pdfBytes2.byteLength);
       };
 
       await expect(noErrorFunc()).resolves.not.toThrowError();
     });
   });
-});
 
-describe(`copy() method`, () => {
-  let pdfDoc: PDFDocument;
-  let srcDoc: PDFDocument;
-  beforeAll(async () => {
-    const parseSpeed = ParseSpeeds.Fastest;
-    srcDoc = await PDFDocument.load(unencryptedPdfBytes, { parseSpeed });
-    const title = '🥚 The Life of an Egg 🍳';
-    const author = 'Humpty Dumpty';
-    const subject = '📘 An Epic Tale of Woe 📖';
-    const keywords = ['eggs', 'wall', 'fall', 'king', 'horses', 'men', '🥚'];
-    const producer = 'PDF App 9000 🤖';
-    const creator = 'PDF App 8000 🤖';
-
-    // Milliseconds  will not get saved, so these dates do not have milliseconds.
-    const creationDate = new Date('1997-08-15T01:58:37Z');
-    const modificationDate = new Date('2018-12-21T07:00:11Z');
-
-    srcDoc.setTitle(title);
-    srcDoc.setAuthor(author);
-    srcDoc.setSubject(subject);
-    srcDoc.setKeywords(keywords);
-    srcDoc.setProducer(producer);
-    srcDoc.setCreator(creator);
-    srcDoc.setCreationDate(creationDate);
-    srcDoc.setModificationDate(modificationDate);
-    pdfDoc = await srcDoc.copy();
-  });
+  describe(`copy() method`, () => {
+    let pdfDoc: PDFDocument;
+    let srcDoc: PDFDocument;
+    beforeAll(async () => {
+      const parseSpeed = ParseSpeeds.Fastest;
+      srcDoc = await PDFDocument.load(unencryptedPdfBytes, { parseSpeed });
+      const title = '🥚 The Life of an Egg 🍳';
+      const author = 'Humpty Dumpty';
+      const subject = '📘 An Epic Tale of Woe 📖';
+      const keywords = ['eggs', 'wall', 'fall', 'king', 'horses', 'men', '🥚'];
+      const producer = 'PDF App 9000 🤖';
+      const creator = 'PDF App 8000 🤖';
 
-  it(`Returns a pdf with the same number of pages`, async () => {
-    expect(pdfDoc.getPageCount()).toBe(srcDoc.getPageCount());
-  });
+      // Milliseconds  will not get saved, so these dates do not have milliseconds.
+      const creationDate = new Date('1997-08-15T01:58:37Z');
+      const modificationDate = new Date('2018-12-21T07:00:11Z');
+
+      srcDoc.setTitle(title);
+      srcDoc.setAuthor(author);
+      srcDoc.setSubject(subject);
+      srcDoc.setKeywords(keywords);
+      srcDoc.setProducer(producer);
+      srcDoc.setCreator(creator);
+      srcDoc.setCreationDate(creationDate);
+      srcDoc.setModificationDate(modificationDate);
+      pdfDoc = await srcDoc.copy();
+    });
 
-  it(`Can copy author, creationDate, creator, producer, subject, title, defaultWordBreaks`, async () => {
-    expect(pdfDoc.getAuthor()).toBe(srcDoc.getAuthor());
-    expect(pdfDoc.getCreationDate()).toStrictEqual(srcDoc.getCreationDate());
-    expect(pdfDoc.getCreator()).toBe(srcDoc.getCreator());
-    expect(pdfDoc.getModificationDate()).toStrictEqual(
-      srcDoc.getModificationDate(),
-    );
-    expect(pdfDoc.getProducer()).toBe(srcDoc.getProducer());
-    expect(pdfDoc.getSubject()).toBe(srcDoc.getSubject());
-    expect(pdfDoc.getTitle()).toBe(srcDoc.getTitle());
-    expect(pdfDoc.defaultWordBreaks).toEqual(srcDoc.defaultWordBreaks);
+    it(`Returns a pdf with the same number of pages`, async () => {
+      expect(pdfDoc.getPageCount()).toBe(srcDoc.getPageCount());
+    });
+
+    it(`Can copy author, creationDate, creator, producer, subject, title, defaultWordBreaks`, async () => {
+      expect(pdfDoc.getAuthor()).toBe(srcDoc.getAuthor());
+      expect(pdfDoc.getCreationDate()).toStrictEqual(srcDoc.getCreationDate());
+      expect(pdfDoc.getCreator()).toBe(srcDoc.getCreator());
+      expect(pdfDoc.getModificationDate()).toStrictEqual(
+        srcDoc.getModificationDate(),
+      );
+      expect(pdfDoc.getProducer()).toBe(srcDoc.getProducer());
+      expect(pdfDoc.getSubject()).toBe(srcDoc.getSubject());
+      expect(pdfDoc.getTitle()).toBe(srcDoc.getTitle());
+      expect(pdfDoc.defaultWordBreaks).toEqual(srcDoc.defaultWordBreaks);
+    });
   });
 });
diff --git a/tests/api/PDFImage.spec.ts b/tests/api/PDFImage.spec.ts
@@ -1,62 +1,59 @@
-import { PDFDocument, PDFImage } from "src/api";
-import { PngEmbedder } from "src/core";
-import { toUint8Array } from "src/utils";
+import { PDFDocument, PDFImage } from 'src/api';
+import { PngEmbedder } from 'src/core';
+import { toUint8Array } from 'src/utils';
 
-
-const examplePngImage = "data:image/png;base64,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";
+const examplePngImage =
+  'data:image/png;base64,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';
 
 describe(`PDFImage`, () => {
-
   describe(`embed() method`, () => {
-    it(`The embedder field should be cleared after the first call to embed()`, async () => {
+    it(`clears the 'embedder' field after the first call`, async () => {
       const pdfDoc = await PDFDocument.create();
 
       const bytes = toUint8Array(examplePngImage);
       const embedder = await PngEmbedder.for(bytes);
       const ref = pdfDoc.context.nextRef();
       const pdfImage = PDFImage.of(ref, pdfDoc, embedder);
 
-      const embedderVariable = "embedder";
+      const embedderVariable = 'embedder';
       expect(pdfImage[embedderVariable]).toBeDefined();
       await pdfImage.embed();
       expect(pdfImage[embedderVariable]).toBeUndefined();
     });
-    it(`The method embed() may be called several times without an error`, async () => {
+
+    it(`may be called multiple times without causing an error`, async () => {
       const pdfDoc = await PDFDocument.create();
 
       const bytes = toUint8Array(examplePngImage);
       const embedder = await PngEmbedder.for(bytes);
       const ref = pdfDoc.context.nextRef();
       const pdfImage = PDFImage.of(ref, pdfDoc, embedder);
 
-      const noErrorFunc = async () => {
-        await pdfImage.embed();
-        await pdfImage.embed();
-      }
-
-      await expect(noErrorFunc()).resolves.not.toThrowError();
+      await expect(pdfImage.embed()).resolves.not.toThrowError();
+      await expect(pdfImage.embed()).resolves.not.toThrowError();
     });
-    it(`The method embed() may be called parallel without causing an error`, async () => {
+
+    it(`may be called in parallel without causing an error`, async () => {
       const pdfDoc = await PDFDocument.create();
 
       const bytes = toUint8Array(examplePngImage);
       const embedder = await PngEmbedder.for(bytes);
       const ref = pdfDoc.context.nextRef();
       const pdfImage = PDFImage.of(ref, pdfDoc, embedder);
 
-      const noErrorFunc = async () => {
-        const embedderTaskVariable = "embedderTask";
-        const undefinedTask = pdfImage[embedderTaskVariable];
-        expect(undefinedTask).toBeUndefined();
-        const task1 = pdfImage.embed();
-        const firstTask = pdfImage[embedderTaskVariable];
-        const task2 = pdfImage.embed();
-        const secondTask = pdfImage[embedderTaskVariable];
-        await Promise.all([task1, task2]);
-        expect(firstTask).toEqual(secondTask);
-      }
-
-      await expect(noErrorFunc()).resolves.not.toThrowError();
+      const task = () => pdfImage['embedTask'];
+
+      expect(task()).toBeUndefined();
+
+      const task1 = pdfImage.embed();
+      const firstTask = task();
+
+      const task2 = pdfImage.embed();
+      const secondTask = task();
+
+      await Promise.all([task1, task2]);
+
+      expect(firstTask).toEqual(secondTask);
     });
   });
-});
+});