Merge branch 'preview' of https://github.com/Azure/AppConfiguration-J…

…avaScriptProvider into zhiyuanliang/enforce-api-version-for-cdn

src/AzureAppConfigurationImpl.ts

@@ -43,6 +43,10 @@
 import { KeyFilter, LabelFilter, SettingSelector } from "./types.js";
 import { ConfigurationClientManager } from "./ConfigurationClientManager.js";
 import { ETAG_LOOKUP_HEADER } from "./EtagUrlPipelinePolicy.js";
+import { getFixedBackoffDuration, getExponentialBackoffDuration } from "./common/backoffUtils.js";
+import { InvalidOperationError, ArgumentError, isFailoverableError, isInputError } from "./common/error.js";
+
+const MIN_DELAY_FOR_UNHANDLED_FAILURE = 5_000; // 5 seconds
 
 type PagedSettingSelector = SettingSelector & {
     pageEtags?: string[];
@@ -249,39 +253,40 @@
      * @internal
      */
     async load() {
-        await this.#inspectFmPackage();
-        await this.#loadSelectedAndWatchedKeyValues();
-
-        if (this.#featureFlagEnabled) {
-            await this.#loadFeatureFlags();
-        }
-
-        if (this.#isCdnUsed) {
-            if (this.#watchAll) { // collection monitoring based refresh
-                // use the first page etag of the first kv selector
-                const defaultSelector = this.#kvSelectorCollection.selectors.find(s => s.pageEtags !== undefined);
-                if (defaultSelector && defaultSelector.pageEtags!.length > 0) {
-                    this.#kvSelectorCollection.cdnCacheBreakString = defaultSelector.pageEtags![0];
-                } else {
-                    this.#kvSelectorCollection.cdnCacheBreakString = undefined;
-                }
-            } else if (this.#refreshEnabled) { // watched settings based refresh
-                // use the etag of the first watched setting (sentinel)
-                this.#kvSelectorCollection.cdnCacheBreakString = this.#sentinels.find(s => s.etag !== undefined)?.etag;
-            }
-
-            if (this.#featureFlagRefreshEnabled) {
-                const defaultSelector = this.#ffSelectorCollection.selectors.find(s => s.pageEtags !== undefined);
-                if (defaultSelector && defaultSelector.pageEtags!.length > 0) {
-                    this.#ffSelectorCollection.cdnCacheBreakString = defaultSelector.pageEtags![0];
-                } else {
-                    this.#ffSelectorCollection.cdnCacheBreakString = undefined;
+        const startTimestamp = Date.now();
+        const startupTimeout: number = this.#options?.startupOptions?.timeoutInMs ?? DEFAULT_STARTUP_TIMEOUT_IN_MS;
+        const abortController = new AbortController();
+        const abortSignal = abortController.signal;
+        let timeoutId;
+        try {
+            // Promise.race will be settled when the first promise in the list is settled.
+            // It will not cancel the remaining promises in the list.
+            // To avoid memory leaks, we must ensure other promises will be eventually terminated.
+            await Promise.race([
+                this.#initializeWithRetryPolicy(abortSignal),
+                // this promise will be rejected after timeout
+                new Promise((_, reject) => {
+                    timeoutId = setTimeout(() => {
+                        abortController.abort(); // abort the initialization promise
+                        reject(new Error("Load operation timed out."));
+                    },
+                    startupTimeout);
+                })
+            ]);
+        } catch (error) {
+            if (!isInputError(error)) {
+                const timeElapsed = Date.now() - startTimestamp;
+                if (timeElapsed < MIN_DELAY_FOR_UNHANDLED_FAILURE) {
+                    // load() method is called in the application's startup code path.
+                    // Unhandled exceptions cause application crash which can result in crash loops as orchestrators attempt to restart the application.
+                    // Knowing the intended usage of the provider in startup code path, we mitigate back-to-back crash loops from overloading the server with requests by waiting a minimum time to propagate fatal errors.
+                    await new Promise(resolve => setTimeout(resolve, MIN_DELAY_FOR_UNHANDLED_FAILURE - timeElapsed));
                 }
             }
+            throw new Error("Failed to load.", { cause: error });
+        } finally {
+            clearTimeout(timeoutId); // cancel the timeout promise
         }
-
-        // mark all settings have loaded at startup.
-        this.#isInitialLoadCompleted = true;
     }
 
     /**
@@ -380,6 +385,31 @@
                     if (this.#featureFlagEnabled) {
                         await this.#loadFeatureFlags();
                     }
+
+                    if (this.#isCdnUsed) {
+                        if (this.#watchAll) { // collection monitoring based refresh
+                            // use the first page etag of the first kv selector
+                            const defaultSelector = this.#kvSelectorCollection.selectors.find(s => s.pageEtags !== undefined);
+                            if (defaultSelector && defaultSelector.pageEtags!.length > 0) {
+                                this.#kvSelectorCollection.cdnCacheBreakString = defaultSelector.pageEtags![0];
+                            } else {
+                                this.#kvSelectorCollection.cdnCacheBreakString = undefined;
+                            }
+                        } else if (this.#refreshEnabled) { // watched settings based refresh
+                            // use the etag of the first watched setting (sentinel)
+                            this.#kvSelectorCollection.cdnCacheBreakString = this.#sentinels.find(s => s.etag !== undefined)?.etag;
+                        }
+
+                        if (this.#featureFlagRefreshEnabled) {
+                            const defaultSelector = this.#ffSelectorCollection.selectors.find(s => s.pageEtags !== undefined);
+                            if (defaultSelector && defaultSelector.pageEtags!.length > 0) {
+                                this.#ffSelectorCollection.cdnCacheBreakString = defaultSelector.pageEtags![0];
+                            } else {
+                                this.#ffSelectorCollection.cdnCacheBreakString = undefined;
+                            }
+                        }
+                    }
+
                     this.#isInitialLoadCompleted = true;
                     break;
                 } catch (error) {

src/load.ts

@@ -5,8 +5,9 @@ import { TokenCredential } from "@azure/identity";
 import { AzureAppConfiguration } from "./AzureAppConfiguration.js";
 import { AzureAppConfigurationImpl } from "./AzureAppConfigurationImpl.js";
 import { AzureAppConfigurationOptions } from "./AzureAppConfigurationOptions.js";
-import { ConfigurationClientManager, instanceOfTokenCredential } from "./ConfigurationClientManager.js";
+import { ConfigurationClientManager } from "./ConfigurationClientManager.js";
 import { EtagUrlPipelinePolicy } from "./EtagUrlPipelinePolicy.js";
+import { instanceOfTokenCredential } from "./common/utils.js";
 
 const MIN_DELAY_FOR_UNHANDLED_ERROR: number = 5_000; // 5 seconds
 
@@ -89,4 +90,4 @@ export async function loadFromCdn(
     };
 
     return await load(cdnEndpoint, emptyTokenCredential, appConfigOptions);
-}
+}