Remove need for timeout failsafe

All the failure routes should either:
- Get far enough along to not leave checked values unable to reach the finished state...
- or all be tied into the same AbortController so everything aborts together.

... I think...

javascript/gallery.js

@@ -23,10 +23,14 @@ const el = {
 
 const SUPPORTED_EXTENSIONS = ['jpg', 'jpeg', 'png', 'webp', 'tiff', 'jp2', 'jxl', 'gif', 'mp4', 'mkv', 'avi', 'mjpeg', 'mpg', 'avr'];
 
-async function awaitForIDB(num = 0, signal = null) {
-  const timeout = AbortSignal.timeout(180000); // Failsafe to ensure no memory leaks
-  const combinedSignals = signal ? AbortSignal.any([timeout, signal]) : timeout;
-  while (outstanding > num && !combinedSignals.aborted) await new Promise((resolve) => { setTimeout(resolve, 50); });
+/**
+ * Wait for the `outstanding` variable to be below the specified value
+ * @param {number} num - Threshold for `outstanding`
+ * @param {AbortSignal} signal - AbortController signal
+ */
+async function awaitForOutstanding(num, signal) {
+  while (outstanding > num && !signal.aborted) await new Promise((resolve) => { setTimeout(resolve, 50); });
+  signal.throwIfAborted();
 }
 
 /**
@@ -35,9 +39,8 @@ async function awaitForIDB(num = 0, signal = null) {
  * @param {AbortSignal} signal - AbortController signal
  */
 async function awaitForGallery(expectedSize, signal) {
-  const timeout = AbortSignal.timeout(180000); // Failsafe to ensure no memory leaks
-  const combinedSignals = AbortSignal.any([timeout, signal]);
-  while (galleryHashes.size < expectedSize && !combinedSignals.aborted) await new Promise((resolve) => { setTimeout(resolve, 500); }); // longer interval because it's a low priority check
+  while (galleryHashes.size < expectedSize && !signal.aborted) await new Promise((resolve) => { setTimeout(resolve, 500); }); // longer interval because it's a low priority check
+  signal.throwIfAborted();
 }
 
 function updateGalleryStyles() {
@@ -270,29 +273,32 @@ async function addSeparators() {
   }
 }
 
-async function delayFetchThumb(fn) {
-  await awaitForIDB(16);
-  outstanding++;
-  const ts = Date.now().toString();
-  const res = await authFetch(`${window.api}/browser/thumb?file=${encodeURI(fn)}&ts=${ts}`, { priority: 'low' });
-  if (!res.ok) {
-    error(`fetchThumb: ${res.statusText}`);
+async function delayFetchThumb(fn, signal) {
+  await awaitForOutstanding(16, signal);
+  try {
+    outstanding++;
+    const ts = Date.now().toString();
+    const res = await authFetch(`${window.api}/browser/thumb?file=${encodeURI(fn)}&ts=${ts}`, { priority: 'low' });
+    if (!res.ok) {
+      error(`fetchThumb: ${res.statusText}`);
+      return undefined;
+    }
+    const json = await res.json();
+    if (!res || !json || json.error || Object.keys(json).length === 0) {
+      if (json.error) error(`fetchThumb: ${json.error}`);
+      return undefined;
+    }
+    return json;
+  } finally {
     outstanding--;
-    return undefined;
   }
-  const json = await res.json();
-  outstanding--;
-  if (!res || !json || json.error || Object.keys(json).length === 0) {
-    if (json.error) error(`fetchThumb: ${json.error}`);
-    return undefined;
-  }
-  return json;
 }
 
 class GalleryFile extends HTMLElement {
+  /** @type {AbortSignal} */
   #signal;
 
-  constructor(folder, file, signal = undefined) {
+  constructor(folder, file, signal) {
     super();
     this.folder = folder;
     this.name = file;
@@ -324,7 +330,7 @@ class GalleryFile extends HTMLElement {
     }
 
     this.hash = await getHash(`${this.folder}/${this.name}/${this.size}/${this.mtime}`); // eslint-disable-line no-use-before-define
-    const cache = (this.hash && opts.browser_cache) ? await idbGet(this.hash) : undefined;
+    const cache = (this.hash && opts.browser_cache) ? await idbGet(this.hash).catch(() => undefined) : undefined;
     const img = document.createElement('img');
     img.className = 'gallery-file';
     img.loading = 'lazy';
@@ -348,7 +354,7 @@ class GalleryFile extends HTMLElement {
       this.mtime = new Date(cache.mtime);
     } else {
       try {
-        const json = await delayFetchThumb(this.src);
+        const json = await delayFetchThumb(this.src, this.#signal);
         if (!json) {
           ok = false;
         } else {
@@ -377,14 +383,13 @@ class GalleryFile extends HTMLElement {
         img.src = `file=${this.src}`;
       }
     }
-    if (this.#signal && !this.#signal.aborted) {
-      // Guard against accessing external context from a stale initialization
-      galleryHashes.add(this.hash); // Add to hashes Set *after* any database operations
-      this.#signal = null; // Clean up reference to AbortSignal
-    }
-    if (!ok) {
+    if (this.#signal.aborted) { // Do not change the operations order from here...
       return;
     }
+    galleryHashes.add(this.hash);
+    if (!ok) {
+      return;
+    } // ... to here unless modifications are also being made to maintenance functionality and the usage of AbortController/AbortSignal
     img.onclick = () => {
       currentImage = this.src;
       el.btnSend.click();

javascript/indexdb.js

@@ -90,6 +90,8 @@ async function idbGetAllKeys(index = null, query = null) {
     try {
       let request;
       const transaction = db.transaction('thumbs', 'readonly');
+      transaction.onabort = (e) => reject(e);
+
       const store = transaction.objectStore('thumbs');
       if (index) {
         request = store.index(index).getAllKeys(query);
@@ -98,7 +100,6 @@ async function idbGetAllKeys(index = null, query = null) {
       }
       request.onsuccess = () => resolve(request.result);
       request.onerror = (e) => reject(e);
-      transaction.onabort = (e) => reject(e);
     } catch (err) {
       reject(err);
     }
@@ -117,6 +118,8 @@ async function idbCount(folder = null) {
     try {
       let request;
       const transaction = db.transaction('thumbs', 'readonly');
+      transaction.onabort = (e) => reject(e);
+
       const store = transaction.objectStore('thumbs');
       if (folder) {
         request = store.index('folder').count(folder);
@@ -125,7 +128,6 @@ async function idbCount(folder = null) {
       }
       request.onsuccess = () => resolve(request.result);
       request.onerror = (e) => reject(e);
-      transaction.onabort = (e) => reject(e);
     } catch (err) {
       reject(err);
     }
@@ -161,15 +163,6 @@ async function idbFolderCleanup(keepSet, folder, signal) {
       transaction.abort();
     }
     signal.addEventListener('abort', abortTransaction);
-
-    try {
-      const store = transaction.objectStore('thumbs');
-      removals.forEach((entry) => { store.delete(entry); });
-    } catch (err) {
-      error(err);
-      abortTransaction();
-    }
-
     transaction.onabort = () => {
       signal.removeEventListener('abort', abortTransaction);
       reject(`Aborting. ${signal.reason}`); // eslint-disable-line prefer-promise-reject-errors
@@ -182,6 +175,14 @@ async function idbFolderCleanup(keepSet, folder, signal) {
       signal.removeEventListener('abort', abortTransaction);
       resolve(totalRemovals);
     };
+
+    try {
+      const store = transaction.objectStore('thumbs');
+      removals.forEach((entry) => { store.delete(entry); });
+    } catch (err) {
+      error(err);
+      abortTransaction();
+    }
   });
 }