🐎 Improve performance

src/cdn/funcs/saveResponse.ts

@@ -13,30 +13,19 @@ export default function saveResponse(
   }
 
   //Remember file size
-  const headerLength = Number(response.headers['content-length']);
+  //const headerLength = Number(response.headers['content-length']);
 
   const writeStream = fs.createWriteStream(filePath);
 
   //If we receive a part of the response, write it to disk
-  let totalLength = 0;
-  response.on('data', (chunk: Buffer) => {
-    totalLength += chunk.length;
-
-    //Exit early if we received too much data
-    if (totalLength > headerLength) {
-      return reject(`Expected length ${headerLength} but received at least ${totalLength}.`);
-    }
-
-    //Write chunk to disk
-    writeStream.write(chunk);
-  });
+  response.pipe(writeStream);
 
   //If we finished reading response, check for correctness, then return it
   response.on('end', () => {
     //Check that length is correct
-    if (totalLength !== headerLength) {
+    /*if (totalLength !== headerLength) {
       return reject(`Expected length ${headerLength} but received ${totalLength}.`);
-    }
+    }*/
 
     //wait until everything is written to disk, then return file name
     writeStream.end(() => {

src/ssn/decryption/decryptChunk.ts

@@ -4,7 +4,7 @@ export default function getDecryptor(decryptionKeys: [number, number, number]) {
   let [key0, key1, key2] = decryptionKeys;
 
   return (encryptedChunk: Buffer) => {
-    const decryptedChunk = Buffer.alloc(encryptedChunk.length);
+    //const decryptedChunk = Buffer.alloc(encryptedChunk.length);
 
     for (let i = 0; i < encryptedChunk.length; i += 1) {
       //read byte
@@ -19,9 +19,11 @@ export default function getDecryptor(decryptionKeys: [number, number, number]) {
       [key0, key1, key2] = updateKeys([key0, key1, key2], curChar);
 
       //write byte
-      decryptedChunk.writeUInt8(curChar, i);
+      //decryptedChunk.writeUInt8(curChar, i);
+      encryptedChunk.writeUInt8(curChar, i);
     }
 
-    return decryptedChunk;
+    //return decryptedChunk;
+    return encryptedChunk;
   };
 }

src/ssn/extractFileAsStream.ts

@@ -1,10 +1,7 @@
-//Similar to extractFile.ts, but instead of receiving and returning an ArrayBuffer, works with Node.js streams.
-
-import * as fs from 'fs';
 import * as stream from 'stream';
 import * as zlib from 'zlib';
 import { ISsnFileEntry } from '../interfaces/ISsnFileEntry';
-import decryptStream from './streams/decryptStream';
+import decryptTransform from './streams/decryptTransform';
 import readBytesFromStream from './streams/readBytesFromStream';
 
 /** Extracts the file with the given metadata from the stream.
@@ -16,8 +13,8 @@ export default async function extractFileAsStream(file: ISsnFileEntry, inputStre
 
   //pipe into decryption if file is encrypted
   if (file.decryptionKeys !== undefined) {
-    const decryptTransform = decryptStream(file.decryptionKeys);
-    curStream = curStream.pipe(decryptTransform);
+    const transform = decryptTransform(file.decryptionKeys);
+    curStream = curStream.pipe(transform);
     //skip encryption header
     await readBytesFromStream(curStream, 12);
   }

src/ssn/streams/arrayBufferToStream.ts

@@ -12,6 +12,7 @@ export default function arrayBufferToStream(arrayBuffer: ArrayBuffer, offset: nu
 
   let position = offset;
   const endPosition = (length !== undefined) ? (offset + length) : arrayBuffer.byteLength;
+  const byteArray = new Uint8Array(arrayBuffer);
   const outStream = new stream.Readable({
     read(size) {
       const chunkSize = Math.min(size || BUFFER_SIZE, endPosition - position); //TODO: we can probably remove BUFFER_SIZE
@@ -24,7 +25,12 @@ export default function arrayBufferToStream(arrayBuffer: ArrayBuffer, offset: nu
         }
 
         //Write chunk to stream
-        const chunk = Buffer.from(arrayBuffer, position, chunkSize);
+        const chunk = Buffer.allocUnsafe(chunkSize);
+        for (let i = 0; i < chunkSize; i += 1) {
+          chunk.writeUInt8(byteArray[position + i], i);
+        }
+        //chunk.fill(arrayBuffer, position);
+        //const chunk = Buffer.from(arrayBuffer, position, chunkSize);
         position += chunk.length;
         needMoreData = this.push(chunk);
       } while (needMoreData);

src/ssn/streams/getFileFromDisks.ts

@@ -18,7 +18,7 @@ function createFileStream(disks: string[], index: number, offset: number, length
 /** Takes a list of ReadableStreams (the disks), as well as the offset and length, and returns a stream for just one file. */
 async function getConcatenatedStream(disks: string[], { diskStart, offset, length }: IGetFileFromDisksOptions): Promise<stream.Readable> {
   let curDiskIndex = diskStart;
-  let curDisk: fs.ReadStream = createFileStream(disks, diskStart, offset);
+  let curDisk: fs.ReadStream = createFileStream(disks, diskStart, offset, length);
   let totalRead = 0;
 
   //Create new stream that concatenates disks until storedSize is reached, then ends the stream.

src/ssn/xdelta3/performDiffing.ts

@@ -4,7 +4,6 @@ import * as stream from 'stream';
 
 export default function performDiffing(sourceFile: string, diffStream: stream.Readable, targetFile: string): Promise<void> {
   return new Promise((resolve, reject) => {
-    //const sourceStream = fs.createReadStream(sourceFile);
     const targetStream = fs.createWriteStream(targetFile);
 
     //spawn xdelta3 process, set up listeners