Merge pull request #27 from ChainSafe/init-with-promise

Cache a promise for Bls instead of Bls

src/context.ts

@@ -1,22 +1,34 @@
 /* eslint-disable require-atomic-updates */
-import blsWasmWrapper from "@chainsafe/eth2-bls-wasm";
+import bls from "@chainsafe/eth2-bls-wasm";
 
-let blsWrapper: typeof blsWasmWrapper | null = null;
+type Bls = typeof bls;
+let blsGlobal: Bls | null = null;
+let blsGlobalPromise: Promise<Bls> | null = null;
 
-export async function init(): Promise<typeof blsWasmWrapper> {
-  if(blsWrapper) return blsWrapper;
-  await blsWasmWrapper.init();
-  blsWrapper = blsWasmWrapper;
-  return blsWrapper;
+export async function setupBls(): Promise<Bls> {
+  if (!blsGlobal) {
+    await bls.init();
+    blsGlobal = bls;
+  }
+  return blsGlobal;
+}
+
+// Cache a promise for Bls instead of Bls to make sure it is initialized only once
+export async function init(): Promise<Bls> {
+  if (!blsGlobalPromise) {
+    blsGlobalPromise = setupBls();
+  }
+  return blsGlobalPromise;
 }
 
 export function destroy(): void {
-  blsWrapper = null;
+  blsGlobal = null;
+  blsGlobalPromise = null;
 }
 
-export function getContext(): typeof blsWasmWrapper{
-  if(blsWrapper) {
-    return blsWrapper;
+export function getContext(): Bls {
+  if (!blsGlobal) {
+    throw new Error("BLS not initialized");
   }
-  throw new Error("BLS not initialized");
+  return blsGlobal;
 }