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refactor(file): avoid eviction race of chunks cache (#2761)

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This commit is contained in:
Huang Xin
2025-12-22 12:59:40 +08:00
committed by GitHub
parent 4b4ebdbdaa
commit a460e609fa
1 changed files with 73 additions and 33 deletions
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apps/readest-app/src/utils/file.ts
+73 -33
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@@ -66,8 +66,9 @@ export class NativeFile extends File implements ClosableFile {
static MAX_CACHE_CHUNK_SIZE = 1024 * 1024;
static MAX_CACHE_ITEMS_SIZE = 50;
#cache: Map<number, ArrayBuffer> = new Map();
#order: number[] = [];
#cache: Map<number, ArrayBuffer> = new Map();
#pendingReads: Map<string, Promise<ArrayBuffer>> = new Map();
constructor(fp: string, name?: string, baseDir: BaseDirectory | null = null, type = '') {
super([], name || fp, { type });
@@ -122,37 +123,54 @@ export class NativeFile extends File implements ClosableFile {
// exclusive reading of the end: [start, end)
async readData(start: number, end: number): Promise<ArrayBuffer> {
// PDF.js workers might call readData concurrently
// make readData thread-safe by always opening and closing the file handle
const handle = await open(this.#fp, this.#baseDir ? { baseDir: this.#baseDir } : undefined);
if (!handle) {
throw new Error('File handle is not open');
}
start = Math.max(0, start);
end = Math.max(start, Math.min(this.size, end));
const size = end - start;
try {
start = Math.max(0, start);
end = Math.max(start, Math.min(this.size, end));
const size = end - start;
if (size > NativeFile.MAX_CACHE_CHUNK_SIZE) {
if (size > NativeFile.MAX_CACHE_CHUNK_SIZE) {
const handle = await open(this.#fp, this.#baseDir ? { baseDir: this.#baseDir } : undefined);
try {
await handle.seek(start, SeekMode.Start);
const buffer = new Uint8Array(size);
await handle.read(buffer);
return buffer.buffer;
} finally {
await handle.close();
}
}
const cachedChunkStart = Array.from(this.#cache.keys()).find((chunkStart) => {
const buffer = this.#cache.get(chunkStart)!;
return start >= chunkStart && end <= chunkStart + buffer.byteLength;
});
const cachedChunkStart = Array.from(this.#cache.keys()).find((chunkStart) => {
const buffer = this.#cache.get(chunkStart)!;
return start >= chunkStart && end <= chunkStart + buffer.byteLength;
});
if (cachedChunkStart !== undefined) {
this.#updateAccessOrder(cachedChunkStart);
const buffer = this.#cache.get(cachedChunkStart)!;
const offset = start - cachedChunkStart;
return buffer.slice(offset, offset + size);
}
if (cachedChunkStart !== undefined) {
this.#updateAccessOrder(cachedChunkStart);
const buffer = this.#cache.get(cachedChunkStart)!;
const offset = start - cachedChunkStart;
return buffer.slice(offset, offset + size);
}
const readKey = `${start}-${end}`;
const pendingRead = this.#pendingReads.get(readKey);
if (pendingRead) {
return pendingRead;
}
const readPromise = this.#readAndCacheChunkSafe(start, size);
this.#pendingReads.set(readKey, readPromise);
try {
return await readPromise;
} finally {
this.#pendingReads.delete(readKey);
}
}
async #readAndCacheChunkSafe(start: number, size: number): Promise<ArrayBuffer> {
const handle = await open(this.#fp, this.#baseDir ? { baseDir: this.#baseDir } : undefined);
try {
const chunkStart = Math.max(0, start - 1024);
const chunkEnd = Math.min(this.size, start + NativeFile.MAX_CACHE_CHUNK_SIZE);
const chunkSize = chunkEnd - chunkStart;
@@ -161,6 +179,7 @@ export class NativeFile extends File implements ClosableFile {
const buffer = new Uint8Array(chunkSize);
await handle.read(buffer);
// Only one thread reaches here per unique range
this.#cache.set(chunkStart, buffer.buffer);
this.#updateAccessOrder(chunkStart);
this.#ensureCacheSize();
@@ -249,11 +268,12 @@ export class RemoteFile extends File implements ClosableFile {
#lastModified: number;
#size: number = -1;
#type: string = '';
#cache: Map<number, ArrayBuffer> = new Map(); // LRU cache
#order: number[] = [];
#cache: Map<number, ArrayBuffer> = new Map(); // LRU cache
#pendingFetches: Map<string, Promise<ArrayBuffer>> = new Map();
static MAX_CACHE_CHUNK_SIZE = 1024 * 128;
static MAX_CACHE_ITEMS_SIZE: number = 256;
static MAX_CACHE_ITEMS_SIZE: number = 128;
constructor(url: string, name?: string, type = '', lastModified = Date.now()) {
const basename = url.split('/').pop() || 'remote-file';
@@ -347,7 +367,7 @@ export class RemoteFile extends File implements ClosableFile {
} else if (rangeSize > RemoteFile.MAX_CACHE_CHUNK_SIZE) {
return this.fetchRangePart(start, end);
} else {
let cachedChunkStart = Array.from(this.#cache.keys()).find((chunkStart) => {
const cachedChunkStart = Array.from(this.#cache.keys()).find((chunkStart) => {
const buffer = this.#cache.get(chunkStart)!;
const bufferSize = buffer.byteLength;
return start >= chunkStart && end <= chunkStart + bufferSize;
@@ -358,20 +378,40 @@ export class RemoteFile extends File implements ClosableFile {
const offset = start - cachedChunkStart;
return buffer.slice(offset, offset + rangeSize);
}
cachedChunkStart = await this.#fetchAndCacheChunk(start, end);
const buffer = this.#cache.get(cachedChunkStart)!;
const offset = start - cachedChunkStart;
return buffer.slice(offset, offset + rangeSize);
const fetchKey = `${start}-${end}`;
const pendingFetch = this.#pendingFetches.get(fetchKey);
if (pendingFetch) {
return pendingFetch;
}
const fetchPromise = this.#fetchAndCacheChunkSafe(start, end, rangeSize);
this.#pendingFetches.set(fetchKey, fetchPromise);
try {
return await fetchPromise;
} finally {
this.#pendingFetches.delete(fetchKey);
}
}
}
async #fetchAndCacheChunk(start: number, end: number): Promise<number> {
async #fetchAndCacheChunkSafe(
start: number,
end: number,
rangeSize: number,
): Promise<ArrayBuffer> {
const chunkStart = Math.max(0, start - 1024);
const chunkEnd = Math.max(end, start + RemoteFile.MAX_CACHE_CHUNK_SIZE - 1024 - 1);
this.#cache.set(chunkStart, await this.fetchRangePart(chunkStart, chunkEnd));
const buffer = await this.fetchRangePart(chunkStart, chunkEnd);
// Only one thread reaches here per unique range
this.#cache.set(chunkStart, buffer);
this.#updateAccessOrder(chunkStart);
this.#ensureCacheSize();
return chunkStart;
const offset = start - chunkStart;
return buffer.slice(offset, offset + rangeSize);
}
#updateAccessOrder(chunkStart: number) {