썸네일 로딩 로직 최적화

src/lib/components/atoms/buttons/FileThumbnailButton.svelte

@@ -1,7 +1,6 @@
 <script lang="ts">
-  import { browser } from "$app/environment";
+  import { getFileThumbnail } from "$lib/modules/file";
   import type { SummarizedFileInfo } from "$lib/modules/filesystem";
-  import { requestFileThumbnailDownload } from "$lib/services/file";
 
   interface Props {
     info: SummarizedFileInfo;
@@ -10,25 +9,16 @@
 
   let { info, onclick }: Props = $props();
 
-  let showThumbnail = $derived(
-    browser && (info.contentType.startsWith("image/") || info.contentType.startsWith("video/")),
-  );
-  let thumbnailPromise = $derived(
-    showThumbnail ? requestFileThumbnailDownload(info.id, info.dataKey?.key) : null,
-  );
+  let thumbnail = $derived(getFileThumbnail(info));
 </script>
 
 <button
   onclick={onclick && (() => setTimeout(() => onclick(info), 100))}
   class="aspect-square overflow-hidden rounded transition active:scale-95 active:brightness-90"
 >
-  {#await thumbnailPromise}
+  {#if $thumbnail}
+    <img src={$thumbnail} alt={info.name} class="h-full w-full object-cover" />
+  {:else}
     <div class="h-full w-full bg-gray-100"></div>
-  {:then thumbnail}
-    {#if thumbnail}
-      <img src={thumbnail} alt={info.name} class="h-full w-full object-cover" />
-    {:else}
-      <div class="h-full w-full bg-gray-100"></div>
-    {/if}
-  {/await}
+  {/if}
 </button>

src/lib/components/organisms/Category/File.svelte

@@ -1,9 +1,8 @@
 <script lang="ts">
-  import { browser } from "$app/environment";
   import { ActionEntryButton } from "$lib/components/atoms";
   import { DirectoryEntryLabel } from "$lib/components/molecules";
+  import { getFileThumbnail } from "$lib/modules/file";
   import type { CategoryFileInfo } from "$lib/modules/filesystem";
-  import { requestFileThumbnailDownload } from "$lib/services/file";
   import type { SelectedFile } from "./service";
 
   import IconClose from "~icons/material-symbols/close";
@@ -16,12 +15,7 @@
 
   let { info, onclick, onRemoveClick }: Props = $props();
 
-  let showThumbnail = $derived(
-    browser && (info.contentType.startsWith("image/") || info.contentType.startsWith("video/")),
-  );
-  let thumbnailPromise = $derived(
-    showThumbnail ? requestFileThumbnailDownload(info.id, info.dataKey?.key) : null,
-  );
+  let thumbnail = $derived(getFileThumbnail(info));
 </script>
 
 <ActionEntryButton
@@ -30,9 +24,5 @@
   actionButtonIcon={onRemoveClick && IconClose}
   onActionButtonClick={() => onRemoveClick?.(info)}
 >
-  {#await thumbnailPromise}
-    <DirectoryEntryLabel type="file" name={info.name} />
-  {:then thumbnail}
-    <DirectoryEntryLabel type="file" thumbnail={thumbnail ?? undefined} name={info.name} />
-  {/await}
+  <DirectoryEntryLabel type="file" thumbnail={$thumbnail} name={info.name} />
 </ActionEntryButton>

src/lib/modules/file/cache.ts

@@ -1,15 +1,12 @@
-import { LRUCache } from "lru-cache";
 import {
   getFileCacheIndex as getFileCacheIndexFromIndexedDB,
   storeFileCacheIndex,
   deleteFileCacheIndex,
   type FileCacheIndex,
 } from "$lib/indexedDB";
-import { readFile, writeFile, deleteFile, deleteDirectory } from "$lib/modules/opfs";
-import { getThumbnailUrl } from "$lib/modules/thumbnail";
+import { readFile, writeFile, deleteFile } from "$lib/modules/opfs";
 
 const fileCacheIndex = new Map<number, FileCacheIndex>();
-const loadedThumbnails = new LRUCache<number, string>({ max: 100 });
 
 export const prepareFileCache = async () => {
   for (const cache of await getFileCacheIndexFromIndexedDB()) {
@@ -51,30 +48,3 @@ export const deleteFileCache = async (fileId: number) => {
   await deleteFile(`/cache/${fileId}`);
   await deleteFileCacheIndex(fileId);
 };
-
-export const getFileThumbnailCache = async (fileId: number) => {
-  const thumbnail = loadedThumbnails.get(fileId);
-  if (thumbnail) return thumbnail;
-
-  const thumbnailBuffer = await readFile(`/thumbnail/file/${fileId}`);
-  if (!thumbnailBuffer) return null;
-
-  const thumbnailUrl = getThumbnailUrl(thumbnailBuffer);
-  loadedThumbnails.set(fileId, thumbnailUrl);
-  return thumbnailUrl;
-};
-
-export const storeFileThumbnailCache = async (fileId: number, thumbnailBuffer: ArrayBuffer) => {
-  await writeFile(`/thumbnail/file/${fileId}`, thumbnailBuffer);
-  loadedThumbnails.set(fileId, getThumbnailUrl(thumbnailBuffer));
-};
-
-export const deleteFileThumbnailCache = async (fileId: number) => {
-  loadedThumbnails.delete(fileId);
-  await deleteFile(`/thumbnail/file/${fileId}`);
-};
-
-export const deleteAllFileThumbnailCaches = async () => {
-  loadedThumbnails.clear();
-  await deleteDirectory("/thumbnail/file");
-};

src/lib/modules/file/index.ts

@@ -1,3 +1,4 @@
 export * from "./cache";
 export * from "./download.svelte";
+export * from "./thumbnail";
 export * from "./upload.svelte";

src/lib/modules/file/thumbnail.ts

@@ -0,0 +1,90 @@
+import { LRUCache } from "lru-cache";
+import { writable, type Writable } from "svelte/store";
+import { browser } from "$app/environment";
+import { decryptData } from "$lib/modules/crypto";
+import type { SummarizedFileInfo } from "$lib/modules/filesystem";
+import { readFile, writeFile, deleteFile, deleteDirectory } from "$lib/modules/opfs";
+import { getThumbnailUrl } from "$lib/modules/thumbnail";
+import { isTRPCClientError, trpc } from "$trpc/client";
+
+const loadedThumbnails = new LRUCache<number, Writable<string>>({ max: 100 });
+const loadingThumbnails = new Map<number, Writable<string | undefined>>();
+
+const fetchFromOpfs = async (fileId: number) => {
+  const thumbnailBuffer = await readFile(`/thumbnail/file/${fileId}`);
+  if (thumbnailBuffer) {
+    return getThumbnailUrl(thumbnailBuffer);
+  }
+};
+
+const fetchFromServer = async (fileId: number, dataKey: CryptoKey) => {
+  try {
+    const [thumbnailEncrypted, { contentIv: thumbnailEncryptedIv }] = await Promise.all([
+      fetch(`/api/file/${fileId}/thumbnail/download`),
+      trpc().file.thumbnail.query({ id: fileId }),
+    ]);
+    const thumbnailBuffer = await decryptData(
+      await thumbnailEncrypted.arrayBuffer(),
+      thumbnailEncryptedIv,
+      dataKey,
+    );
+
+    void writeFile(`/thumbnail/file/${fileId}`, thumbnailBuffer);
+    return getThumbnailUrl(thumbnailBuffer);
+  } catch (e) {
+    if (isTRPCClientError(e) && e.data?.code === "NOT_FOUND") {
+      return null;
+    }
+    throw e;
+  }
+};
+
+export const getFileThumbnail = (file: SummarizedFileInfo) => {
+  if (
+    !browser ||
+    !(file.contentType.startsWith("image/") || file.contentType.startsWith("video/"))
+  ) {
+    return undefined;
+  }
+
+  const thumbnail = loadedThumbnails.get(file.id);
+  if (thumbnail) return thumbnail;
+
+  let loadingThumbnail = loadingThumbnails.get(file.id);
+  if (loadingThumbnail) return loadingThumbnail;
+
+  loadingThumbnail = writable(undefined);
+  loadingThumbnails.set(file.id, loadingThumbnail);
+
+  fetchFromOpfs(file.id)
+    .then((thumbnail) => thumbnail ?? (file.dataKey && fetchFromServer(file.id, file.dataKey.key)))
+    .then((thumbnail) => {
+      if (thumbnail) {
+        loadingThumbnail.set(thumbnail);
+        loadedThumbnails.set(file.id, loadingThumbnail as Writable<string>);
+      }
+      loadingThumbnails.delete(file.id);
+    });
+  return loadingThumbnail;
+};
+
+export const storeFileThumbnailCache = async (fileId: number, thumbnailBuffer: ArrayBuffer) => {
+  await writeFile(`/thumbnail/file/${fileId}`, thumbnailBuffer);
+
+  const oldThumbnail = loadedThumbnails.get(fileId);
+  if (oldThumbnail) {
+    oldThumbnail.set(getThumbnailUrl(thumbnailBuffer));
+  } else {
+    loadedThumbnails.set(fileId, writable(getThumbnailUrl(thumbnailBuffer)));
+  }
+};
+
+export const deleteFileThumbnailCache = async (fileId: number) => {
+  loadedThumbnails.delete(fileId);
+  await deleteFile(`/thumbnail/file/${fileId}`);
+};
+
+export const deleteAllFileThumbnailCaches = async () => {
+  loadedThumbnails.clear();
+  await deleteDirectory(`/thumbnail/file`);
+};

src/lib/modules/file/upload.svelte.ts

@@ -196,77 +196,74 @@ export const uploadFile = async (
   });
   const state = uploadingFiles.at(-1)!;
 
-  return await scheduler.schedule(
-    async () => file.size,
-    async () => {
-      state.status = "encryption-pending";
+  return await scheduler.schedule(file.size, async () => {
+    state.status = "encryption-pending";
 
-      try {
-        const { fileBuffer, fileSigned } = await requestDuplicateFileScan(
-          file,
-          hmacSecret,
-          onDuplicate,
-        );
-        if (!fileBuffer || !fileSigned) {
-          state.status = "canceled";
-          uploadingFiles = uploadingFiles.filter((file) => file !== state);
-          return undefined;
-        }
+    try {
+      const { fileBuffer, fileSigned } = await requestDuplicateFileScan(
+        file,
+        hmacSecret,
+        onDuplicate,
+      );
+      if (!fileBuffer || !fileSigned) {
+        state.status = "canceled";
+        uploadingFiles = uploadingFiles.filter((file) => file !== state);
+        return undefined;
+      }
 
-        const {
-          dataKeyWrapped,
-          dataKeyVersion,
-          fileType,
-          fileEncrypted,
-          fileEncryptedHash,
-          nameEncrypted,
-          createdAtEncrypted,
-          lastModifiedAtEncrypted,
-          thumbnail,
-        } = await encryptFile(state, file, fileBuffer, masterKey);
+      const {
+        dataKeyWrapped,
+        dataKeyVersion,
+        fileType,
+        fileEncrypted,
+        fileEncryptedHash,
+        nameEncrypted,
+        createdAtEncrypted,
+        lastModifiedAtEncrypted,
+        thumbnail,
+      } = await encryptFile(state, file, fileBuffer, masterKey);
 
-        const form = new FormData();
-        form.set(
+      const form = new FormData();
+      form.set(
+        "metadata",
+        JSON.stringify({
+          parent: parentId,
+          mekVersion: masterKey.version,
+          dek: dataKeyWrapped,
+          dekVersion: dataKeyVersion.toISOString(),
+          hskVersion: hmacSecret.version,
+          contentHmac: fileSigned,
+          contentType: fileType,
+          contentIv: fileEncrypted.iv,
+          name: nameEncrypted.ciphertext,
+          nameIv: nameEncrypted.iv,
+          createdAt: createdAtEncrypted?.ciphertext,
+          createdAtIv: createdAtEncrypted?.iv,
+          lastModifiedAt: lastModifiedAtEncrypted.ciphertext,
+          lastModifiedAtIv: lastModifiedAtEncrypted.iv,
+        } satisfies FileUploadRequest),
+      );
+      form.set("content", new Blob([fileEncrypted.ciphertext]));
+      form.set("checksum", fileEncryptedHash);
+
+      let thumbnailForm = null;
+      if (thumbnail) {
+        thumbnailForm = new FormData();
+        thumbnailForm.set(
           "metadata",
           JSON.stringify({
-            parent: parentId,
-            mekVersion: masterKey.version,
-            dek: dataKeyWrapped,
             dekVersion: dataKeyVersion.toISOString(),
-            hskVersion: hmacSecret.version,
-            contentHmac: fileSigned,
-            contentType: fileType,
-            contentIv: fileEncrypted.iv,
-            name: nameEncrypted.ciphertext,
-            nameIv: nameEncrypted.iv,
-            createdAt: createdAtEncrypted?.ciphertext,
-            createdAtIv: createdAtEncrypted?.iv,
-            lastModifiedAt: lastModifiedAtEncrypted.ciphertext,
-            lastModifiedAtIv: lastModifiedAtEncrypted.iv,
-          } satisfies FileUploadRequest),
+            contentIv: thumbnail.iv,
+          } satisfies FileThumbnailUploadRequest),
         );
-        form.set("content", new Blob([fileEncrypted.ciphertext]));
-        form.set("checksum", fileEncryptedHash);
-
-        let thumbnailForm = null;
-        if (thumbnail) {
-          thumbnailForm = new FormData();
-          thumbnailForm.set(
-            "metadata",
-            JSON.stringify({
-              dekVersion: dataKeyVersion.toISOString(),
-              contentIv: thumbnail.iv,
-            } satisfies FileThumbnailUploadRequest),
-          );
-          thumbnailForm.set("content", new Blob([thumbnail.ciphertext]));
-        }
-
-        const { fileId } = await requestFileUpload(state, form, thumbnailForm);
-        return { fileId, fileBuffer, thumbnailBuffer: thumbnail?.plaintext };
-      } catch (e) {
-        state.status = "error";
-        throw e;
+        thumbnailForm.set("content", new Blob([thumbnail.ciphertext]));
       }
-    },
-  );
+
+      const { fileId } = await requestFileUpload(state, form, thumbnailForm);
+      return { fileId, fileBuffer, thumbnailBuffer: thumbnail?.plaintext };
+    } catch (e) {
+      state.status = "error";
+      throw e;
+    }
+  });
 };

src/lib/modules/scheduler.ts

@@ -1,39 +1,46 @@
 export class Scheduler<T = void> {
-  private tasks = 0;
+  private isEstimating = false;
   private memoryUsage = 0;
   private queue: (() => void)[] = [];
 
-  constructor(public memoryLimit = 100 * 1024 * 1024 /* 100 MiB */) {}
+  constructor(public readonly memoryLimit = 100 * 1024 * 1024 /* 100 MiB */) {}
 
   private next() {
-    if (this.memoryUsage < this.memoryLimit) {
-      this.queue.shift()?.();
+    if (!this.isEstimating && this.memoryUsage < this.memoryLimit) {
+      const resolve = this.queue.shift();
+      if (resolve) {
+        this.isEstimating = true;
+        resolve();
+      }
     }
   }
 
-  async schedule(estimateMemoryUsage: () => Promise<number>, task: () => Promise<T>) {
-    if (this.tasks++ > 0) {
+  async schedule(
+    estimateMemoryUsage: number | (() => number | Promise<number>),
+    task: () => Promise<T>,
+  ) {
+    if (this.isEstimating || this.memoryUsage >= this.memoryLimit) {
       await new Promise<void>((resolve) => {
         this.queue.push(resolve);
       });
-    }
-
-    while (this.memoryUsage >= this.memoryLimit) {
-      await new Promise<void>((resolve) => {
-        this.queue.unshift(resolve);
-      });
+    } else {
+      this.isEstimating = true;
     }
 
     let taskMemoryUsage = 0;
 
     try {
-      taskMemoryUsage = await estimateMemoryUsage();
+      taskMemoryUsage =
+        typeof estimateMemoryUsage === "number" ? estimateMemoryUsage : await estimateMemoryUsage();
       this.memoryUsage += taskMemoryUsage;
+    } finally {
+      this.isEstimating = false;
       this.next();
+    }
 
+    try {
       return await task();
     } finally {
-      this.tasks--;
       this.memoryUsage -= taskMemoryUsage;
       this.next();
     }

src/lib/services/file.ts

@@ -1,15 +1,11 @@
 import { getAllFileInfos } from "$lib/indexedDB/filesystem";
-import { decryptData } from "$lib/modules/crypto";
 import {
   getFileCache,
   storeFileCache,
   deleteFileCache,
-  getFileThumbnailCache,
-  storeFileThumbnailCache,
-  deleteFileThumbnailCache,
   downloadFile,
+  deleteFileThumbnailCache,
 } from "$lib/modules/file";
-import { getThumbnailUrl } from "$lib/modules/thumbnail";
 import type { FileThumbnailUploadRequest } from "$lib/server/schemas";
 import { trpc } from "$trpc/client";
 
@@ -44,29 +40,6 @@ export const requestFileThumbnailUpload = async (
   return await fetch(`/api/file/${fileId}/thumbnail/upload`, { method: "POST", body: form });
 };
 
-export const requestFileThumbnailDownload = async (fileId: number, dataKey?: CryptoKey) => {
-  const cache = await getFileThumbnailCache(fileId);
-  if (cache || !dataKey) return cache;
-
-  let thumbnailInfo;
-  try {
-    thumbnailInfo = await trpc().file.thumbnail.query({ id: fileId });
-  } catch {
-    // TODO: Error Handling
-    return null;
-  }
-  const { contentIv: thumbnailEncryptedIv } = thumbnailInfo;
-
-  const res = await fetch(`/api/file/${fileId}/thumbnail/download`);
-  if (!res.ok) return null;
-
-  const thumbnailEncrypted = await res.arrayBuffer();
-  const thumbnailBuffer = await decryptData(thumbnailEncrypted, thumbnailEncryptedIv, dataKey);
-
-  storeFileThumbnailCache(fileId, thumbnailBuffer); // Intended
-  return getThumbnailUrl(thumbnailBuffer);
-};
-
 export const requestDeletedFilesCleanup = async () => {
   let liveFiles;
   try {

src/routes/(main)/directory/[[id]]/DirectoryEntries/File.svelte

@@ -1,9 +1,8 @@
 <script lang="ts">
-  import { browser } from "$app/environment";
   import { ActionEntryButton } from "$lib/components/atoms";
   import { DirectoryEntryLabel } from "$lib/components/molecules";
+  import { getFileThumbnail } from "$lib/modules/file";
   import type { SummarizedFileInfo } from "$lib/modules/filesystem";
-  import { requestFileThumbnailDownload } from "$lib/services/file";
   import { formatDateTime } from "$lib/utils";
   import type { SelectedEntry } from "../service.svelte";
 
@@ -17,12 +16,7 @@
 
   let { info, onclick, onOpenMenuClick }: Props = $props();
 
-  let showThumbnail = $derived(
-    browser && (info.contentType.startsWith("image/") || info.contentType.startsWith("video/")),
-  );
-  let thumbnailPromise = $derived(
-    showThumbnail ? requestFileThumbnailDownload(info.id, info.dataKey?.key) : null,
-  );
+  let thumbnail = $derived(getFileThumbnail(info));
 
   const action = (callback: typeof onclick) => {
     callback({ type: "file", id: info.id, dataKey: info.dataKey, name: info.name });
@@ -35,18 +29,10 @@
   actionButtonIcon={IconMoreVert}
   onActionButtonClick={() => action(onOpenMenuClick)}
 >
-  {#await thumbnailPromise}
-    <DirectoryEntryLabel
-      type="file"
-      name={info.name}
-      subtext={formatDateTime(info.createdAt ?? info.lastModifiedAt)}
-    />
-  {:then thumbnail}
-    <DirectoryEntryLabel
-      type="file"
-      thumbnail={thumbnail ?? undefined}
-      name={info.name}
-      subtext={formatDateTime(info.createdAt ?? info.lastModifiedAt)}
-    />
-  {/await}
+  <DirectoryEntryLabel
+    type="file"
+    thumbnail={$thumbnail}
+    name={info.name}
+    subtext={formatDateTime(info.createdAt ?? info.lastModifiedAt)}
+  />
 </ActionEntryButton>