From 6e206184b6e2f1c79967f34f144aae70eaaa44d8 Mon Sep 17 00:00:00 2001
From: PepijnSenders <ps@hellofresh.com>
Date: Tue, 17 Jan 2023 17:50:01 +0100
Subject: [PATCH] Run project config parse inside web worker

---
 .../project_config/parseDatafileWorker.ts     | 33 +++++++++
 .../project_config/project_config_manager.ts  | 70 ++++++++++++++-----
 2 files changed, 87 insertions(+), 16 deletions(-)
 create mode 100644 packages/optimizely-sdk/lib/core/project_config/parseDatafileWorker.ts

diff --git a/packages/optimizely-sdk/lib/core/project_config/parseDatafileWorker.ts b/packages/optimizely-sdk/lib/core/project_config/parseDatafileWorker.ts
new file mode 100644
index 000000000..6eea981ab
--- /dev/null
+++ b/packages/optimizely-sdk/lib/core/project_config/parseDatafileWorker.ts
@@ -0,0 +1,33 @@
+import { tryCreatingProjectConfig } from '.';
+
+const messageListener = (e: MessageEvent<{ type: string; payload: { datafile: string | object } }>) => {
+  if (e.data.type === 'START_PARSE_DATAFILE') {
+    const { configObj, error } = tryCreatingProjectConfig({
+      datafile: e.data.payload.datafile,
+      logger: {
+        log: (...args) => {
+          console.log(...args);
+        },
+      },
+    });
+
+    if (error) {
+      postMessage({
+        type: 'DATAFILE_PARSE_ERROR',
+        payload: {
+          error: error.message,
+          parsedDatafile: null
+        }
+      })
+    } else {
+      postMessage({
+        type: 'DATAFILE_PARSE_SUCCESS',
+        payload: {
+          parsedDatafile: configObj
+        }
+      })
+    }
+  }
+};
+
+addEventListener('message', messageListener);
diff --git a/packages/optimizely-sdk/lib/core/project_config/project_config_manager.ts b/packages/optimizely-sdk/lib/core/project_config/project_config_manager.ts
index aea5951bd..ebbbd7bbd 100644
--- a/packages/optimizely-sdk/lib/core/project_config/project_config_manager.ts
+++ b/packages/optimizely-sdk/lib/core/project_config/project_config_manager.ts
@@ -18,11 +18,7 @@ import { sprintf } from '../../utils/fns';
 
 import { ERROR_MESSAGES } from '../../utils/enums';
 import { createOptimizelyConfig } from '../optimizely_config';
-import {
-  OnReadyResult,
-  OptimizelyConfig,
-  DatafileManager,
-} from '../../shared_types';
+import { OnReadyResult, OptimizelyConfig, DatafileManager } from '../../shared_types';
 import { ProjectConfig, toDatafile, tryCreatingProjectConfig } from '../project_config';
 
 const logger = getLogger();
@@ -31,12 +27,13 @@ const MODULE_NAME = 'PROJECT_CONFIG_MANAGER';
 interface ProjectConfigManagerConfig {
   // TODO[OASIS-6649]: Don't use object type
   // eslint-disable-next-line  @typescript-eslint/ban-types
-  datafile?: string | object,
+  datafile?: string | object;
   jsonSchemaValidator?: {
-    validate(jsonObject: unknown): boolean,
+    validate(jsonObject: unknown): boolean;
   };
-  sdkKey?: string,
-  datafileManager?: DatafileManager
+  sdkKey?: string;
+  datafileManager?: DatafileManager;
+  useWebWorker?: boolean;
 }
 
 /**
@@ -74,7 +71,9 @@ export class ProjectConfigManager {
       this.jsonSchemaValidator = config.jsonSchemaValidator;
 
       if (!config.datafile && !config.sdkKey) {
-        const datafileAndSdkKeyMissingError = new Error(sprintf(ERROR_MESSAGES.DATAFILE_AND_SDK_KEY_MISSING, MODULE_NAME));
+        const datafileAndSdkKeyMissingError = new Error(
+          sprintf(ERROR_MESSAGES.DATAFILE_AND_SDK_KEY_MISSING, MODULE_NAME)
+        );
         this.readyPromise = Promise.resolve({
           success: false,
           reason: getErrorMessage(datafileAndSdkKeyMissingError),
@@ -85,10 +84,14 @@ export class ProjectConfigManager {
 
       let handleNewDatafileException = null;
       if (config.datafile) {
-        handleNewDatafileException = this.handleNewDatafile(config.datafile);
+        if (config.useWebWorker) {
+          this.readyPromise = this.handleDatafileInWebWorker(config.datafile);
+        } else {
+          handleNewDatafileException = this.handleNewDatafile(config.datafile);
+        }
       }
 
-      if (config.sdkKey &&  config.datafileManager) {
+      if (config.sdkKey && config.datafileManager) {
         this.datafileManager = config.datafileManager;
         this.datafileManager.start();
         this.readyPromise = this.datafileManager
@@ -105,7 +108,7 @@ export class ProjectConfigManager {
           reason: getErrorMessage(handleNewDatafileException, 'Invalid datafile'),
         });
       }
-    } catch (ex: any) {
+    } catch (ex) {
       logger.error(ex);
       this.readyPromise = Promise.resolve({
         success: false,
@@ -137,7 +140,7 @@ export class ProjectConfigManager {
     return {
       success: false,
       reason: getErrorMessage(null, 'Datafile manager is not provided'),
-    }
+    };
   }
 
   /**
@@ -180,7 +183,7 @@ export class ProjectConfigManager {
     const { configObj, error } = tryCreatingProjectConfig({
       datafile: newDatafile,
       jsonSchemaValidator: this.jsonSchemaValidator,
-      logger: logger
+      logger: logger,
     });
 
     if (error) {
@@ -197,6 +200,41 @@ export class ProjectConfigManager {
     return error;
   }
 
+  private async handleDatafileInWebWorker(newDatafile: string | object): Promise<OnReadyResult> {
+    const workerCode = '';
+    const workerBlob = new Blob([workerCode]);
+    const workerUrl = URL.createObjectURL(workerBlob);
+    const worker = new Worker(workerUrl);
+
+    return new Promise((resolve, reject) => {
+      worker.onmessage = (
+        e: MessageEvent<{ type: string; payload: { parsedDatafile: ProjectConfig | null; error?: string } }>
+      ) => {
+        if (e.data.type === 'DATAFILE_PARSE_SUCCESS') {
+          this.configObj = e.data.payload.parsedDatafile;
+
+          resolve({
+            success: true,
+          });
+        }
+
+        if (e.data.type === 'DATAFILE_PARSE_ERROR') {
+          reject({
+            success: false,
+            reason: e.data.payload.error,
+          });
+        }
+      };
+
+      worker.postMessage({
+        type: 'START_PARSE_DATAFILE',
+        payload: {
+          datafile: newDatafile,
+        },
+      });
+    });
+  }
+
   /**
    * Returns the current project config object, or null if no project config object
    * is available
@@ -248,7 +286,7 @@ export class ProjectConfigManager {
    * @param  {Function} listener
    * @return {Function}
    */
-  onUpdate(listener: (config: ProjectConfig) => void): (() => void) {
+  onUpdate(listener: (config: ProjectConfig) => void): () => void {
     this.updateListeners.push(listener);
     return () => {
       const index = this.updateListeners.indexOf(listener);