From 91f65872e0afe60ca92c8433cdf2c7222ec9ee15 Mon Sep 17 00:00:00 2001
From: xiangyu <3170102889@zju.edu.cn>
Date: Tue, 18 Oct 2022 10:51:15 +0800
Subject: [PATCH] resolve: memory leak

---
 addon/chrome/content/previewPDF.html | 23 +++++++++++++++---
 src/events.ts                        |  2 +-
 src/preview.ts                       | 36 +++++++++++++++++++++-------
 3 files changed, 49 insertions(+), 12 deletions(-)

diff --git a/addon/chrome/content/previewPDF.html b/addon/chrome/content/previewPDF.html
index 6057770..b6f3a90 100644
--- a/addon/chrome/content/previewPDF.html
+++ b/addon/chrome/content/previewPDF.html
@@ -110,11 +110,14 @@
     <div id="viewerContainer" class="pdfViewer"></div>
 
     <script>
+      Components.utils.import("resource://gre/modules/osfile.jsm");
+
       var cachedData = {
         itemID: -1,
         pdfDocument: undefined,
         appAnnotations: [],
         viewportWidth: 0,
+        previewType: -1,
       };
       var noteIcon = `<svg xmlns="http://www.w3.org/2000/svg" width="__size__" height="__size__" viewBox="0 0 24 24"><polygon fill="__color__" points="0.5 0.5 23.5 0.5 23.5 23.5 11.5 23.5 0.5 12.5 0.5 0.5"></polygon><polygon points="0.5 12.5 11.5 12.5 11.5 23.5 0.5 12.5" fill="#fff" opacity="0.4"></polygon><path d="M0,0V12.707L11.293,24H24V0ZM11,22.293,1.707,13H11ZM23,23H12V12H1V1H23Z"></path></svg>`;
       var MIN_SCALE = 0.25;
@@ -126,6 +129,7 @@
       var zoomTime = 0;
 
       function updateToolbar(previewType) {
+        cachedData.previewType = previewType;
         const viewerContainer = document.getElementById("viewerContainer");
         const toolbar = document.querySelector(".toolbar");
         const showToolbar =
@@ -134,7 +138,15 @@
           (previewType === 2 && Zotero.Prefs.get("pdfpreview.showToolInTab"));
         toolbar.style.visibility = showToolbar ? "visible" : "hidden";
         toolbar.style.height = showToolbar ? "32px" : "0";
-        viewerContainer.style.height = showToolbar ? "calc(100% - 32px)" : "inherit";
+        viewerContainer.style.height = showToolbar
+          ? "calc(100% - 32px)"
+          : "inherit";
+      }
+
+      async function getBuffer(itemID) {
+        let path = await Zotero.Items.get(itemID).getFilePathAsync();
+        let buf = await OS.File.read(path, {});
+        return new Uint8Array(buf).buffer;
       }
 
       function getScale() {
@@ -468,13 +480,18 @@
           if (cachedData.itemID !== e.data.itemID) {
             updateToolbar(e.data.previewType);
             // Destroy worker to avoid memory leak
+            // and increase the previewCount to let the plugin decide
+            // when to destroy the iframe
+            // because the buffers are not free even after the destroy()
+            Zotero.PDFPreview.preview._previewCounts[
+              cachedData.previewType
+            ] += 1;
             cachedData.pdfDocument && cachedData.pdfDocument.destroy();
             cachedData.pdfDocument = await pdfjsLib.getDocument({
-              data: e.data.buffer,
+              data: await getBuffer(e.data.itemID),
               cMapUrl: "resource://zotero/pdf-reader/cmaps/",
               cMapPacked: true,
             }).promise;
-            delete e.data.buffer;
             cachedData.itemID = e.data.itemID;
             cachedData.viewportWidth = e.data.width;
             cachedData.appAnnotations = e.data.annotations;
diff --git a/src/events.ts b/src/events.ts
index e3f8efd..0a19554 100644
--- a/src/events.ts
+++ b/src/events.ts
@@ -92,7 +92,7 @@ class AddonEvents extends AddonModule {
     });
   }
 
-  private doPreview(force: boolean = false) {
+  public doPreview(force: boolean = false) {
     this.updatePreviewTab();
     const previewType = this.getPreviewType();
     console.log(previewType);
diff --git a/src/preview.ts b/src/preview.ts
index 656c916..2aa3eb0 100644
--- a/src/preview.ts
+++ b/src/preview.ts
@@ -1,3 +1,4 @@
+import PDFPreview from "./addon";
 import { PreviewType } from "./base";
 import AddonModule from "./module";
 
@@ -13,12 +14,26 @@ class Annotation {
     this.pageLabel = pageLabel;
   }
 }
+
+const RELOAD_COUNT = 10;
+
 class AddonPreview extends AddonModule {
   item: Zotero.Item;
   lastType: PreviewType;
   _initPromise: any;
   _loadingPromise: any;
   _skipRendering: boolean;
+  _previewCounts: any;
+
+  constructor(parent: PDFPreview) {
+    super(parent);
+    this._previewCounts = {};
+    let type = PreviewType.info;
+    while (type !== PreviewType.null) {
+      this._previewCounts[type] = 0;
+      type++;
+    }
+  }
 
   public async updatePreviewItem(alwaysUpdate: boolean = false) {
     let items = ZoteroPane.getSelectedItems();
@@ -48,13 +63,6 @@ class AddonPreview extends AddonModule {
     return this.item;
   }
 
-  public async getBuffer() {
-    console.log(this.item);
-    let path: string = await this.item.getFilePathAsync();
-    let buf: any = await OS.File.read(path, {});
-    return new Uint8Array(buf).buffer;
-  }
-
   public getPreviewIds(type: PreviewType) {
     let iframeId = "";
     let containerId = "";
@@ -112,8 +120,21 @@ class AddonPreview extends AddonModule {
       return;
     }
 
+    if (this._previewCounts[type] >= RELOAD_COUNT) {
+      this._previewCounts[type] = 0;
+      await this._Addon.events.initPreview(type);
+      this._Addon.events.doPreview(true);
+      return;
+    }
+    await this._Addon.preview._initPromise;
     let { iframe } = this.getPreviewElements(type);
 
+    let t = 0;
+    while (t < 500 && iframe.contentDocument.readyState !== "complete") {
+      await Zotero.Promise.delay(10);
+      t += 10;
+    }
+
     let item = await this.updatePreviewItem(
       type !== this.lastType ||
         // @ts-ignore
@@ -155,7 +176,6 @@ class AddonPreview extends AddonModule {
         {
           type: "renderPreview",
           itemID: this.item.id,
-          buffer: await this.getBuffer(),
           width: width - 40,
           annotations: Zotero.Prefs.get("pdfpreview.showAnnotations")
             ? item