Add initializePerformance()

Author: Feiyang1

packages-exp/performance-exp/src/index.ts

@@ -44,14 +44,32 @@ const DEFAULT_ENTRY_NAME = '[DEFAULT]';
 /**
  * Returns a FirebasePerformance instance for the given app.
  * @param app - The FirebaseApp to use.
+ * @public
+ */
+export function getPerformance(app: FirebaseApp): FirebasePerformance {
+  const provider = _getProvider(app, 'performance-exp');
+  const perfInstance = provider.getImmediate() as PerformanceController;
+  return perfInstance;
+}
+
+/**
+ * Returns a FirebasePerformance instance for the given app. Can only be called once.
+ * @param app - The FirebaseApp to use.
  * @param settings - Optional settings for the Performance instance.
  * @public
  */
-export function getPerformance(
+export function initializePerformance(
   app: FirebaseApp,
   settings?: PerformanceSettings
 ): FirebasePerformance {
   const provider = _getProvider(app, 'performance-exp');
+
+  // throw if an instance was already created.
+  // It could happen if initializePerformance() is called more than once, or getPerformance() is called first.
+  if (provider.isInitialized()) {
+    throw ERROR_FACTORY.create(ErrorCode.ALREADY_INITIALIZED);
+  }
+
   const perfInstance = provider.getImmediate() as PerformanceController;
   perfInstance._init(settings);
   return perfInstance;

packages-exp/performance-exp/src/utils/errors.ts

@@ -33,7 +33,8 @@ export const enum ErrorCode {
   INVALID_ATTRIBUTE_NAME = 'invalid attribute name',
   INVALID_ATTRIBUTE_VALUE = 'invalid attribute value',
   INVALID_CUSTOM_METRIC_NAME = 'invalid custom metric name',
-  INVALID_STRING_MERGER_PARAMETER = 'invalid String merger input'
+  INVALID_STRING_MERGER_PARAMETER = 'invalid String merger input',
+  ALREADY_INITIALIZED = 'already initialized'
 }
 
 const ERROR_DESCRIPTION_MAP: { readonly [key in ErrorCode]: string } = {
@@ -58,7 +59,8 @@ const ERROR_DESCRIPTION_MAP: { readonly [key in ErrorCode]: string } = {
   [ErrorCode.INVALID_CUSTOM_METRIC_NAME]:
     'Custom metric name {$customMetricName} is invalid',
   [ErrorCode.INVALID_STRING_MERGER_PARAMETER]:
-    'Input for String merger is invalid, contact support team to resolve.'
+    'Input for String merger is invalid, contact support team to resolve.',
+  [ErrorCode.ALREADY_INITIALIZED]: 'Performance can only be initialized once.'
 };
 
 interface ErrorParams {

packages/component/src/provider.ts

@@ -186,6 +186,10 @@ export class Provider<T extends Name> {
     return this.component != null;
   }
 
+  isInitialized(identifier: string = DEFAULT_ENTRY_NAME): boolean {
+    return this.instances.has(identifier);
+  }
+
   private getOrInitializeService(
     identifier: string
   ): NameServiceMapping[T] | null {