[api-minor] Add a new takeOwnershipOfData option to allow transferr…

…ing more data to the worker-thread (bug 1809164)

src/display/api.js

@@ -192,6 +192,9 @@ if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("PRODUCTION")) {
  * @property {number} [maxImageSize] - The maximum allowed image size in total
  *   pixels, i.e. width * height. Images above this value will not be rendered.
  *   Use -1 for no limit, which is also the default value.
+ * @property {boolean} [takeOwnershipOfData] - Determines if we can transfer
+ *   TypedArrays provided in e.g. the `data` and `initialData` options, which
+ *   will help reduce main-thread memory usage. The default value is `false`.
  * @property {boolean} [isEvalSupported] - Determines if we can evaluate strings
  *   as JavaScript. Primarily used to improve performance of font rendering, and
  *   when parsing PDF functions. The default value is `true`.
@@ -375,6 +378,9 @@ function getDocument(src) {
         isValidFetchUrl(params.cMapUrl, document.baseURI) &&
         isValidFetchUrl(params.standardFontDataUrl, document.baseURI));
   }
+  if (typeof params.takeOwnershipOfData !== "boolean") {
+    params.takeOwnershipOfData = false;
+  }
   if (typeof params.isEvalSupported !== "boolean") {
     params.isEvalSupported = true;
   }
@@ -513,6 +519,9 @@ async function _fetchDocument(worker, source, pdfDataRangeTransport, docId) {
     source.contentDispositionFilename =
       pdfDataRangeTransport.contentDispositionFilename;
   }
+  const transfers =
+    source.takeOwnershipOfData && source.data ? [source.data.buffer] : null;
+
   const workerId = await worker.messageHandler.sendWithPromise(
     "GetDocRequest",
     // Only send the required properties, and *not* the entire `source` object.
@@ -542,15 +551,10 @@ async function _fetchDocument(worker, source, pdfDataRangeTransport, docId) {
           ? source.standardFontDataUrl
           : null,
       },
-    }
+    },
+    transfers
   );
 
-  // Release the TypedArray data, when it exists, since it's no longer needed
-  // on the main-thread *after* it's been sent to the worker-thread.
-  if (source.data) {
-    source.data = null;
-  }
-
   if (worker.destroyed) {
     throw new Error("Worker was destroyed");
   }

test/unit/api_spec.js

@@ -193,6 +193,45 @@ describe("api", function () {
       expect(data[0] instanceof PDFDocumentProxy).toEqual(true);
       expect(data[1].loaded / data[1].total).toEqual(1);
 
+      // Check that the TypedArray wasn't transferred.
+      expect(typedArrayPdf.length).toEqual(basicApiFileLength);
+
+      await loadingTask.destroy();
+    });
+
+    it("creates pdf doc from TypedArray, with `takeOwnershipOfData` set", async function () {
+      if (isNodeJS) {
+        pending("Worker is not supported in Node.js.");
+      }
+      const typedArrayPdf = await DefaultFileReaderFactory.fetch({
+        path: TEST_PDFS_PATH + basicApiFileName,
+      });
+
+      // Sanity check to make sure that we fetched the entire PDF file.
+      expect(typedArrayPdf instanceof Uint8Array).toEqual(true);
+      expect(typedArrayPdf.length).toEqual(basicApiFileLength);
+
+      const loadingTask = getDocument({
+        data: typedArrayPdf,
+        takeOwnershipOfData: true,
+      });
+      expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
+
+      const progressReportedCapability = createPromiseCapability();
+      loadingTask.onProgress = function (data) {
+        progressReportedCapability.resolve(data);
+      };
+
+      const data = await Promise.all([
+        loadingTask.promise,
+        progressReportedCapability.promise,
+      ]);
+      expect(data[0] instanceof PDFDocumentProxy).toEqual(true);
+      expect(data[1].loaded / data[1].total).toEqual(1);
+
+      // Check that the TypedArray was transferred.
+      expect(typedArrayPdf.length).toEqual(0);
+
       await loadingTask.destroy();
     });
 

web/app_options.js

@@ -270,6 +270,11 @@ const defaultOptions = {
         : "../web/standard_fonts/",
     kind: OptionKind.API,
   },
+  takeOwnershipOfData: {
+    /** @type {boolean} */
+    value: typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL"),
+    kind: OptionKind.API,
+  },
   verbosity: {
     /** @type {number} */
     value: 1,