fix weird stream behavior in some cases

src/classes/caching/file_system_cache.js

@@ -24,13 +24,13 @@ export class FileSystemCache {
 
     const metaBuffer = await cacache.get.byDigest(this.cacheDirectory, metaInfo.integrity);
     const metaData = JSON.parse(metaBuffer);
-    const { bodyStreamIntegrity, bodyStreamLength } = metaData;
+    const { bodyStreamIntegrity, empty } = metaData;
     delete metaData.bodyStreamIntegrity;
-    delete metaData.bodyStreamLength;
+    delete metaData.empty;
 
-    const bodyStream = bodyStreamLength > 0
-      ? cacache.get.stream.byDigest(this.cacheDirectory, bodyStreamIntegrity)
-      : Readable.from(Buffer.alloc(0));
+    const bodyStream = empty
+      ? Readable.from(Buffer.alloc(0))
+      : cacache.get.stream.byDigest(this.cacheDirectory, bodyStreamIntegrity);
 
     return {
       bodyStream,
@@ -49,13 +49,13 @@ export class FileSystemCache {
     ]);
   }
 
-  async set(key, bodyStream, metaData, bodyStreamLength) {
+  async set(key, bodyStream, metaData) {
     const [bodyKey, metaKey] = getBodyAndMetaKeys(key);
-    const metaCopy = { ...metaData, bodyStreamLength };
+    const metaCopy = { ...metaData };
 
     this.keyTimeout.clearTimeout(key);
 
-    if (bodyStreamLength > 0) {
+    try {
       metaCopy.bodyStreamIntegrity = await new Promise((fulfill, reject) => {
         bodyStream.pipe(cacache.put.stream(this.cacheDirectory, bodyKey))
           .on('integrity', (i) => fulfill(i))
@@ -63,13 +63,22 @@ export class FileSystemCache {
             reject(e);
           });
       });
+    } catch (err) {
+      if (err.code !== 'ENODATA') {
+        throw err;
+      }
+
+      metaCopy.empty = true;
     }
 
     const metaBuffer = Buffer.from(JSON.stringify(metaCopy));
     await cacache.put(this.cacheDirectory, metaKey, metaBuffer);
+    const cachedData = await this.get(key);
 
     if (typeof this.ttl === 'number') {
       this.keyTimeout.updateTimeout(key, this.ttl, () => this.remove(key));
     }
+
+    return cachedData;
   }
 }

src/classes/caching/memory_cache.js

@@ -41,5 +41,7 @@ export class MemoryCache {
     if (typeof this.ttl === 'number') {
       this.keyTimeout.updateTimeout(key, this.ttl, () => this.remove(key));
     }
+
+    return this.get(key);
   }
 }

src/classes/response.js

@@ -1,24 +1,15 @@
 import { Response } from 'node-fetch';
-import { PassThrough } from 'stream';
 
 const responseInternalSymbol = Object.getOwnPropertySymbols(new Response())[1];
 
 export class NFCResponse extends Response {
   constructor(bodyStream, metaData, ejectFromCache, fromCache) {
-    const stream1 = new PassThrough();
-    const stream2 = new PassThrough();
-
-    bodyStream.pipe(stream1);
-    bodyStream.pipe(stream2);
-
-    super(stream1, metaData);
+    super(bodyStream, metaData);
     this.ejectFromCache = ejectFromCache;
     this.fromCache = fromCache;
-    this.serializationStream = stream2;
   }
 
-  static fromNodeFetchResponse(res, ejectFromCache) {
-    const bodyStream = res.body;
+  static serializeMetaFromNodeFetchResponse(res) {
     const metaData = {
       url: res.url,
       status: res.status,
@@ -29,30 +20,7 @@ export class NFCResponse extends Response {
       counter: res[responseInternalSymbol].counter,
     };
 
-    return new NFCResponse(bodyStream, metaData, ejectFromCache, false);
-  }
-
-  static fromCachedResponse(bodyStream, rawMetaData, ejectSelfFromCache) {
-    if (bodyStream.readableEnded) {
-      throw new Error('Cache returned a body stream that has already been read to end.');
-    }
-
-    return new NFCResponse(bodyStream, rawMetaData, ejectSelfFromCache, true);
-  }
-
-  serialize() {
-    return {
-      bodyStream: this.serializationStream,
-      metaData: {
-        url: this.url,
-        status: this.status,
-        statusText: this.statusText,
-        headers: this.headers.raw(),
-        size: this.size,
-        timeout: this.timeout,
-        counter: this[responseInternalSymbol].counter,
-      },
-    };
+    return metaData;
   }
 
   ejectFromCache() {

src/index.js

@@ -95,10 +95,11 @@ async function getResponse(cache, requestArguments) {
   const ejectSelfFromCache = () => cache.remove(cacheKey);
 
   if (cachedValue) {
-    return NFCResponse.fromCachedResponse(
+    return new NFCResponse(
       cachedValue.bodyStream,
       cachedValue.metaData,
       ejectSelfFromCache,
+      true,
     );
   }
 
@@ -106,26 +107,29 @@ async function getResponse(cache, requestArguments) {
   try {
     cachedValue = await cache.get(cacheKey);
     if (cachedValue) {
-      return NFCResponse.fromCachedResponse(
+      return new NFCResponse(
         cachedValue.bodyStream,
         cachedValue.metaData,
         ejectSelfFromCache,
+        true,
       );
     }
 
     const fetchResponse = await fetch(...requestArguments);
-    const nfcResponse = NFCResponse.fromNodeFetchResponse(fetchResponse, ejectSelfFromCache);
-    const contentLength = Number.parseInt(nfcResponse.headers.get('content-length'), 10) || 0;
-    const nfcResponseSerialized = nfcResponse.serialize();
+    const serializedMeta = NFCResponse.serializeMetaFromNodeFetchResponse(fetchResponse);
 
-    await cache.set(
+    const newlyCachedData = await cache.set(
       cacheKey,
-      nfcResponseSerialized.bodyStream,
-      nfcResponseSerialized.metaData,
-      contentLength,
+      fetchResponse.body,
+      serializedMeta,
     );
 
-    return nfcResponse;
+    return new NFCResponse(
+      newlyCachedData.bodyStream,
+      newlyCachedData.metaData,
+      ejectSelfFromCache,
+      false,
+    );
   } finally {
     locko.unlock(cacheKey);
   }