Fix issue with in browser Hash (#1738)

Also, make Hash not copy the bytes.

js/package.json

@@ -1,7 +1,7 @@
 {
   "name": "@attic/noms",
   "license": "Apache-2.0",
-  "version": "44.0.0",
+  "version": "44.0.1",
   "description": "Noms JS SDK",
   "repository": "https://github.com/attic-labs/noms",
   "main": "dist/commonjs/noms.js",

js/src/browser/sha1.js

@@ -10,6 +10,7 @@ import Rusha from 'rusha';
 
 const r = new Rusha();
 
-export default function sha1(data: Uint8Array): Uint32Array {
-  return r.rawDigest(data);
+export default function sha1(data: Uint8Array): Uint8Array {
+  const ta = r.rawDigest(data);
+  return new Uint8Array(ta.buffer, ta.byteOffset, ta.byteLength);
 }

js/src/chunk-serializer.js

@@ -101,7 +101,8 @@ function deserializeHints(buffer: ArrayBuffer): {hints: Array<Hash>, offset: num
   for (; offset < totalLength;) {
     invariant(buffer.byteLength - offset >= sha1Size, 'Invalid hint buffer');
 
-    const hashArray = new Uint8Array(buffer, offset, sha1Size);
+    // Make a slice/copy of the ArrayBuffer to prevent `buffer` from being gc'ed.
+    const hashArray = new Uint8Array(buffer.slice(offset, offset + sha1Size));
     const hash = new Hash(hashArray);
     offset += sha1Size;
 
@@ -118,6 +119,7 @@ export function deserializeChunks(buffer: ArrayBuffer, offset: number = 0): Arra
   for (; offset < totalLenth;) {
     invariant(buffer.byteLength - offset >= chunkHeaderSize, 'Invalid chunk buffer');
 
+    // No need to copy the data out since we are not holding on to the hash object.
     const hashArray = new Uint8Array(buffer, offset, sha1Size);
     const hash = new Hash(hashArray);
     offset += sha1Size;
@@ -128,9 +130,8 @@ export function deserializeChunks(buffer: ArrayBuffer, offset: number = 0): Arra
 
     invariant(offset + chunkLength <= totalLenth, 'Invalid chunk buffer');
 
-    const dataArray = new Uint8Array(buffer, offset, chunkLength);
-    const chunk = new Chunk(new Uint8Array(dataArray)); // Makes a slice (copy) of the byte sequence
-                                                        // from buffer.
+    // Make a copy of the data so that buffer can be collected.
+    const chunk = new Chunk(new Uint8Array(buffer.slice(offset, offset + chunkLength)));
 
     invariant(chunk.hash.equals(hash), 'Serialized hash !== computed hash');
 

js/src/codec.js

@@ -128,7 +128,8 @@ export class BinaryNomsReader {
   }
 
   readHash(): Hash {
-    const digest = new Uint8Array(this.buff, this.offset, sha1Size);
+    // Make a copy of the data.
+    const digest = new Uint8Array(this.buff.slice(this.offset, this.offset + sha1Size));
     this.offset += sha1Size;
     return new Hash(digest);
   }

js/src/hash.js

@@ -34,9 +34,12 @@ function sha1ToUint8Array(s: string): Uint8Array {
 export default class Hash {
   _digest: Uint8Array;
 
+  /**
+   * The Hash instance does not copy the `digest` so if the `digest` is part of a large ArrayBuffer
+   * the caller might want to make a copy first to prevent that ArrayBuffer from being retained.
+   */
   constructor(digest: Uint8Array) {
-    // Make a copy to prevent holding on to the data that was passed in.
-    this._digest = new Uint8Array(digest);
+    this._digest = digest;
   }
 
   get digest(): Uint8Array {

samples/js/splore/package.json

@@ -3,7 +3,7 @@
   "license": "Apache-2.0",
   "devDependencies": {
     "@attic/eslintrc": "^3.1.0",
-    "@attic/noms": "^42.0.0",
+    "@attic/noms": "file:../../../js/",
     "@attic/webpack-config": "^2.1.0",
     "babel-cli": "6.6.5",
     "babel-core": "6.7.2",

samples/js/splore/src/main.js

@@ -65,13 +65,15 @@ function load() {
   const httpStore = new HttpBatchStore(params.db, undefined, opts);
   database = new Database(httpStore);
 
-  const setRootHash = hash => {
+  const setRootHash = (hash: Hash) => {
     rootHash = hash;
     handleChunkLoad(hash, hash);
   };
 
   if (params.hash) {
-    setRootHash(Hash.parse(params.ref));
+    const hash = Hash.parse(params.ref);
+    invariant(hash);
+    setRootHash(hash);
   } else {
     httpStore.getRoot().then(setRootHash);
   }
@@ -227,6 +229,7 @@ function handleNodeClick(e: MouseEvent, id: string) {
       render();
     } else {
       const hash = Hash.parse(id);
+      invariant(hash);
       database.readValue(hash).then(value => {
         handleChunkLoad(hash, value, id);
       });