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fix(webdav): 删除文件/目录时按引用计数回收共享缩略图 #87

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Merged
fanchenggang merged 1 commit into from
Sep 6, 2026
Merged

fix(webdav): 删除文件/目录时按引用计数回收共享缩略图 #87

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121 changes: 117 additions & 4 deletions functions/webdav/protocol.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,9 @@ const DAV_ENDPOINT = "/webdav";
const DAV_ENDPOINT_WITH_SLASH = "/webdav/";
const INTERNAL_PREFIX = "_$flaredrive$/";
const THUMBNAIL_PREFIX = "_$flaredrive$/thumbnails/";
const THUMBNAIL_REFS_PREFIX = `${THUMBNAIL_PREFIX}refs/`;
// 缩略图摘要由客户端生成（hex 编码哈希），写入 R2 key 前先校验格式。
const THUMBNAIL_DIGEST_RE = /^[a-f0-9]{16,128}$/;
const DAV_CLASS = "1, 2";
const SUPPORT_METHODS = [
"OPTIONS",
Expand Down Expand Up @@ -116,6 +119,57 @@ function escapeXml(value: string): string {
.replaceAll("'", "'");
}

// —— 缩略图引用计数 ————————————————————————————————
// 缩略图按内容摘要寻址（_$flaredrive$/thumbnails/<digest>.png）并被内容相同的
// 文件共享，删除单个文件时不能直接删图。每个引用文件在
// _$flaredrive$/thumbnails/refs/<digest>/<path> 保留一个不可变 marker 对象，
// 引用清零才回收缩略图。marker 是单次 PUT/DELETE 的独立对象，无读改写竞争：
// 并发删除最坏只会“多留”（无害泄漏），不会误删仍在使用的缩略图。

function isValidThumbnailDigest(digest: unknown): digest is string {
return typeof digest === "string" && THUMBNAIL_DIGEST_RE.test(digest);
}

function thumbnailObjectKey(digest: string): string {
return `${THUMBNAIL_PREFIX}${digest}.png`;
}

function thumbnailRefKey(digest: string, path: string): string {
return `${THUMBNAIL_REFS_PREFIX}${digest}/${path}`;
}

async function addThumbnailRef(
bucket: R2Bucket,
digest: unknown,
path: string,
): Promise<void> {
if (!isValidThumbnailDigest(digest)) return;
await bucket.put(thumbnailRefKey(digest, path), "");
}

/** 引用清零时回收缩略图。 */
async function gcThumbnail(bucket: R2Bucket, digest: unknown): Promise<void> {
if (!isValidThumbnailDigest(digest)) return;
const refs = await bucket.list({
prefix: thumbnailRefKey(digest, ""),
limit: 1,
});
if (refs.objects.length === 0) {
await bucket.delete(thumbnailObjectKey(digest));
}
}

/** 移除单个引用 marker，随后尝试回收缩略图。 */
async function releaseThumbnailRef(
bucket: R2Bucket,
digest: unknown,
path: string,
): Promise<void> {
if (!isValidThumbnailDigest(digest)) return;
await bucket.delete(thumbnailRefKey(digest, path));
await gcThumbnail(bucket, digest);
}

function decodePathSegment(segment: string): string {
try {
return decodeURIComponent(segment);
Expand Down Expand Up @@ -956,16 +1010,34 @@ async function deleteAll(
excludeInternal: boolean = true,
): Promise<void> {
let cursor: string | undefined = undefined;
const releasedDigests = new Set<string>();
do {
const objects = await bucket.list({ prefix, cursor });
const objects = await bucket.list({
prefix,
cursor,
include: ["customMetadata"],
});
const keys = objects.objects
.map((object) => object.key)
.filter((key) => !excludeInternal || !key.startsWith(INTERNAL_PREFIX));
if (keys.length > 0) {
await bucket.delete(keys);
}
// 先逐个移除引用 marker（internal 子树本身不含 marker，无需处理），
// 全部分页结束后再按 digest 去重回收一次缩略图。
for (const object of objects.objects) {
if (excludeInternal && object.key.startsWith(INTERNAL_PREFIX)) continue;
const { thumbnail } = object.customMetadata ?? {};
if (isValidThumbnailDigest(thumbnail)) {
releasedDigests.add(thumbnail);
await bucket.delete(thumbnailRefKey(thumbnail, object.key));
}
}
cursor = objects.truncated ? objects.cursor : undefined;
} while (cursor);
for (const digest of releasedDigests) {
await gcThumbnail(bucket, digest);
}
}

function calcContentRange(object: R2ObjectBody) {
Expand Down Expand Up @@ -1200,10 +1272,22 @@ async function handlePut({

const existing = await bucket.head(path);
const body = await request.arrayBuffer();
const thumbnail = request.headers.get("fd-thumbnail");
const rawThumbnail = request.headers.get("fd-thumbnail");
const thumbnail = isValidThumbnailDigest(rawThumbnail) ? rawThumbnail : undefined;
// 覆盖写入会整体替换 customMetadata；previousThumbnail 是即将被替换掉/保留的旧引用。
const previousThumbnail = existing?.customMetadata?.thumbnail;
const preservedMetadata = getPreservedCustomMetadata(existing?.customMetadata);
if (thumbnail) {
preservedMetadata.thumbnail = thumbnail;
// 引用先行：并发删除最后一个同缩略图文件时不会把图收走。
await addThumbnailRef(bucket, thumbnail, path);
// 客户端先传缩略图本体再传文件；若图在间隙中被并发回收，让客户端整体重试。
if ((await bucket.head(thumbnailObjectKey(thumbnail))) === null) {
if (thumbnail !== previousThumbnail) {
await bucket.delete(thumbnailRefKey(thumbnail, path));
}
return new Response("Thumbnail is missing", { status: 409 });
}
}

const result = await bucket.put(path, body, {
Expand All @@ -1212,9 +1296,16 @@ async function handlePut({
customMetadata: preservedMetadata,
});
if (!result) {
if (thumbnail && thumbnail !== previousThumbnail) {
await bucket.delete(thumbnailRefKey(thumbnail, path));
}
return new Response("Preconditions failed", { status: 412 });
}

if (thumbnail && previousThumbnail !== thumbnail) {
await releaseThumbnailRef(bucket, previousThumbnail, path);
}

return existing === null
? createdResponse(path, false)
: new Response(null, { status: 204 });
Expand Down Expand Up @@ -1276,6 +1367,8 @@ async function handleDelete({

if (path === "") {
await deleteAll(bucket);
// deleteAll 会跳过 internal 子树；全删时把共享缩略图和 marker 一并清掉。
await deleteAll(bucket, THUMBNAIL_PREFIX, false);
return new Response(null, { status: 204 });
}

Expand All @@ -1291,7 +1384,9 @@ async function handleDelete({
await bucket.delete(path);
}
} else {
const digest = resource?.customMetadata?.thumbnail;
await bucket.delete(path);
await releaseThumbnailRef(bucket, digest, path);
}
return new Response(null, { status: 204 });
}
Expand Down Expand Up @@ -1637,10 +1732,19 @@ async function handleCopy({
});
return;
}
// 覆盖同名文件时目标旧缩略图引用需要释放（目录目标已由 deleteDestination 清理，
// 这里兜底处理文件对文件的直接覆盖）。
const previous = await bucket.head(targetKey);
const previousThumbnail = previous?.customMetadata?.thumbnail;
const digest = source.customMetadata?.thumbnail;
await addThumbnailRef(bucket, digest, targetKey);
await bucket.put(targetKey, source.body, {
httpMetadata: source.httpMetadata,
customMetadata: stripLockMetadata(source.customMetadata),
});
if (previousThumbnail !== digest) {
await releaseThumbnailRef(bucket, previousThumbnail, targetKey);
}
};

if (isDirectory) {
Expand Down Expand Up @@ -1785,12 +1889,16 @@ async function handleMove({
});
}
} else {
const digest = source.customMetadata?.thumbnail;
// 先给目标补引用，再释放源引用，缩略图在移动全程都有引用覆盖。
await addThumbnailRef(bucket, digest, target);
await bucket.put(target, source.body, {
httpMetadata: source.httpMetadata,
customMetadata: getPreservedCustomMetadata(source.customMetadata),
});
await bucket.delete(object.key);
await releaseThumbnailRef(bucket, digest, object.key);
}
await bucket.delete(object.key);
};

if (isDirectory) {
Expand Down Expand Up @@ -2016,8 +2124,13 @@ async function handlePostCreateMultipart({
path: string;
request: Request;
}): Promise<Response> {
const thumbnail = request.headers.get("fd-thumbnail");
const rawThumbnail = request.headers.get("fd-thumbnail");
const thumbnail = isValidThumbnailDigest(rawThumbnail) ? rawThumbnail : undefined;
const customMetadata = thumbnail ? { thumbnail } : undefined;
// 引用先行：分片未完成期间，并发删除最后一个同缩略图文件不会把图收走。
if (thumbnail) {
await addThumbnailRef(bucket, thumbnail, path);
}
const multipartUpload = await bucket.createMultipartUpload(path, {
httpMetadata: request.headers,
customMetadata,
Expand Down
8 changes: 5 additions & 3 deletions src/app/__tests__/webdavProtocol.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -580,20 +580,22 @@ describe("webdav PUT", () => {

test("overwrite existing file is 204 and preserves custom metadata", async () => {
const bucket = new InMemoryBucket();
bucket.seed([{ key: "a.txt", body: "old", customMetadata: { thumbnail: "t" } }]);
bucket.seed([{ key: "a.txt", body: "old", customMetadata: { thumbnail: "1".repeat(40) } }]);
// 真实客户端总是先上传缩略图本体，再带 fd-thumbnail 传文件
bucket.seed([{ key: `_$flaredrive$/thumbnails/${"2".repeat(40)}.png`, body: "png" }]);
const response = await call(
req(
"/webdav/a.txt",
"PUT",
{ Authorization: AUTH, "Content-Type": "text/plain", "fd-thumbnail": "new-t" },
{ Authorization: AUTH, "Content-Type": "text/plain", "fd-thumbnail": "2".repeat(40) },
"new"
),
makeEnv(bucket)
);
expect(response.status).toBe(204);
expect(bucket.rawText("a.txt")).toBe("new");
const head = await bucket.asBucket().head("a.txt");
expect(head?.customMetadata?.thumbnail).toBe("new-t");
expect(head?.customMetadata?.thumbnail).toBe("2".repeat(40));
expect(head?.httpMetadata?.contentType).toBe("text/plain");
});

Expand Down
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