Switch to isomorphic hash function to avoid build stress of getting crypto right

Author: airhorns

src/class-model.ts

@@ -30,7 +30,7 @@ import type {
 } from "./types";
 import { $fastInstantiator, buildFastInstantiator } from "./fast-instantiator";
 import memoize from "lodash.memoize";
-import { sha1 } from "./utils";
+import { cyrb53 } from "./utils";
 
 /** @internal */
 type ActionMetadata = {
@@ -296,7 +296,7 @@ export function register<Instance, Klass extends { new (...args: any[]): Instanc
   klass.schemaHash = memoize(async () => {
     const props = Object.entries(klass.properties as Record<string, IAnyType>).sort(([key1], [key2]) => key1.localeCompare(key2));
     const propHashes = await Promise.all(props.map(async ([key, prop]) => `${key}:${await prop.schemaHash()}`));
-    return `model:${klass.name}:${await sha1(propHashes.join("|"))}`;
+    return `model:${klass.name}:${cyrb53(propHashes.join("|"))}`;
   });
 
   // create the MST type for not-readonly versions of this using the views and actions extracted from the class

src/model.ts

@@ -23,7 +23,7 @@ import type {
   IStateTreeNode,
 } from "./types";
 import memoize from "lodash.memoize";
-import { sha1 } from "./utils";
+import { cyrb53 } from "./utils";
 
 export const propsFromModelPropsDeclaration = <Props extends ModelPropertiesDeclaration>(
   propsDecl: Props
@@ -257,7 +257,7 @@ export class ModelType<Props extends ModelProperties, Others> extends BaseType<
   schemaHash: () => Promise<string> = memoize(async () => {
     const props = Object.entries(this.properties).sort(([key1], [key2]) => key1.localeCompare(key2));
     const propHashes = await Promise.all(props.map(async ([key, prop]) => `${key}:${await prop.schemaHash()}`));
-    return `model:${this.name}:${await sha1(propHashes.join("|"))}`;
+    return `model:${this.name}:${cyrb53(propHashes.join("|"))}`;
   });
 }
 

src/union.ts

@@ -1,5 +1,5 @@
 import memoize from "lodash.memoize";
-import type { IType, UnionOptions as MSTUnionOptions } from "mobx-state-tree";
+import type { UnionOptions as MSTUnionOptions } from "mobx-state-tree";
 import { types as mstTypes } from "mobx-state-tree";
 import { BaseType } from "./base";
 import { ensureRegistered, isClassModel } from "./class-model";
@@ -8,7 +8,7 @@ import { OptionalType } from "./optional";
 import { isModelType, isType } from "./api";
 import { LiteralType } from "./simple";
 import { InvalidDiscriminatorError } from "./errors";
-import { sha1 } from "./utils";
+import { cyrb53 } from "./utils";
 
 export type ITypeDispatcher = (snapshot: any) => IAnyType;
 
@@ -138,7 +138,7 @@ class UnionType<Types extends IAnyType[]> extends BaseType<
   }
 
   schemaHash = memoize(async () => {
-    return await sha1(`union:${(await Promise.all(this.types.map((type) => type.schemaHash()))).join("|")}`);
+    return cyrb53(`union:${(await Promise.all(this.types.map((type) => type.schemaHash()))).join("|")}`).toString();
   });
 }
 

src/utils.ts

@@ -1,8 +1,16 @@
-const crypto = typeof window === "undefined" ? require("crypto") : window.crypto;
-
-export async function sha1(source: string) {
-  const sourceBytes = new TextEncoder().encode(source);
-  const digest: ArrayBuffer = await crypto.subtle.digest("SHA-1", sourceBytes);
-  const resultBytes = [...new Uint8Array(digest)];
-  return resultBytes.map((x) => x.toString(16).padStart(2, "0")).join("");
-}
+/**
+ * General purpose fast hashing function that works in the browser and in node.
+ * Credit https://stackoverflow.com/questions/7616461/generate-a-hash-from-string-in-javascript
+ **/
+export const cyrb53 = (str: string, seed = 0) => {
+  let h1 = 0xdeadbeef ^ seed,
+    h2 = 0x41c6ce57 ^ seed;
+  for (let i = 0, ch; i < str.length; i++) {
+    ch = str.charCodeAt(i);
+    h1 = Math.imul(h1 ^ ch, 2654435761);
+    h2 = Math.imul(h2 ^ ch, 1597334677);
+  }
+  h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507) ^ Math.imul(h2 ^ (h2 >>> 13), 3266489909);
+  h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507) ^ Math.imul(h1 ^ (h1 >>> 13), 3266489909);
+  return 4294967296 * (2097151 & h2) + (h1 >>> 0);
+};