1 files changed, 29 insertions, 7 deletions
diff --git a/src/crypto/emscLoader.js b/src/crypto/emscLoader.js
index 59437da42..25dc6b85c 100644
--- a/src/crypto/emscLoader.js
+++ b/src/crypto/emscLoader.js
@@ -25,20 +25,29 @@
  */
 
 let cachedLib = undefined;
+let cachedLibPromise = undefined;
+
+export let enableTracing = false;
 
 /**
  * Load the taler emscripten lib.
  *
  * If in a WebWorker, importScripts is used.  Inside a browser, the module must
  * be globally available.  Inside node, require is used.
+ * 
+ * Returns a Promise<{ lib: EmscLib }>
  */
 export function getLib() {
-  console.log("in getLib");
+  enableTracing && console.log("in getLib");
   if (cachedLib) {
-    console.log("lib is cached");
+    enableTracing && console.log("lib is cached");
     return Promise.resolve({ lib: cachedLib });
   }
+  if (cachedLibPromise) {
+    return cachedLibPromise;
+  }
   if (typeof require !== "undefined") {
+    enableTracing && console.log("trying to load emscripten lib with 'require'");
     // Make sure that TypeScript doesn't try
     // to check the taler-emscripten-lib.
     const indirectRequire = require;
@@ -49,17 +58,30 @@ export function getLib() {
     const savedImportScripts = g.importScripts;
     delete g.importScripts;
     // Assume that the code is run from the build/ directory.
-    const lib = indirectRequire("../../../emscripten/taler-emscripten-lib.js");
+    const libFn = indirectRequire("../../../emscripten/taler-emscripten-lib.js");
+    const lib = libFn();
     g.importScripts = savedImportScripts;
     if (lib) {
-      cachedLib = lib;
-      return Promise.resolve({ lib: cachedLib });
+      if (!lib.ccall) {
+        throw Error("sanity check failed: taler-emscripten lib does not have 'ccall'");
+      }
+      cachedLibPromise = new Promise((resolve, reject) => {
+        lib.onRuntimeInitialized = () => {
+          cachedLib = lib;
+          cachedLibPromise = undefined;
+          resolve({ lib: cachedLib });
+        };
+      });
+      return cachedLibPromise;
+    } else {
+      // When we're running as a webpack bundle, the above require might
+      // have failed and returned 'undefined', so we try other ways to import.
+      console.log("failed to load emscripten lib with 'require', trying alternatives"); 
     }
-    // When we're running as a webpack bundle, the above require might
-    // have failed and returned 'undefined', so we try other ways to import.
   }
 
   if (typeof importScripts !== "undefined") {
+    console.log("trying to load emscripten lib with 'importScripts'");
     self.TalerEmscriptenLib = {};
     importScripts('/emscripten/taler-emscripten-lib.js')
     if (!self.TalerEmscriptenLib) {