list feature flags with pageEtags

Author: Eskibear

src/AzureAppConfigurationImpl.ts

@@ -15,6 +15,13 @@ import { RefreshTimer } from "./refresh/RefreshTimer";
 import { getConfigurationSettingWithTrace, listConfigurationSettingsWithTrace, requestTracingEnabled } from "./requestTracing/utils";
 import { KeyFilter, LabelFilter, SettingSelector } from "./types";
 
+type PagedSettingSelector = SettingSelector & {
+    /**
+     * Key: page eTag, Value: feature flag configurations
+     */
+    pages?: Map<string, ConfigurationSetting[]>
+};
+
 export class AzureAppConfigurationImpl implements AzureAppConfiguration {
     /**
      * Hosting key-value pairs in the configuration store.
@@ -45,6 +52,9 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
     #featureFlagRefreshInterval: number = DEFAULT_REFRESH_INTERVAL_IN_MS;
     #featureFlagRefreshTimer: RefreshTimer;
 
+    // selectors
+    #featureFlagSelectors: PagedSettingSelector[] = [];
+
     constructor(
         client: AppConfigurationClient,
         options: AzureAppConfigurationOptions | undefined
@@ -103,6 +113,9 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
             }
 
             this.#featureFlagRefreshTimer = new RefreshTimer(this.#featureFlagRefreshInterval);
+
+            // validate feature flag selectors
+            this.#featureFlagSelectors = getValidFeatureFlagSelectors(options.featureFlagOptions.selectors);
         }
 
         this.#adapters.push(new AzureKeyVaultKeyValueAdapter(options?.keyVaultOptions));
@@ -233,7 +246,7 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
     }
 
     async #clearLoadedKeyValues() {
-        for(const key of this.#configMap.keys()) {
+        for (const key of this.#configMap.keys()) {
             if (key !== FEATURE_MANAGEMENT_KEY_NAME) {
                 this.#configMap.delete(key);
             }
@@ -243,20 +256,44 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
     async #loadFeatureFlags() {
         // Temporary map to store feature flags, key is the key of the setting, value is the raw value of the setting
         const featureFlagsMap = new Map<string, any>();
-        const featureFlagSelectors = getValidFeatureFlagSelectors(this.#options?.featureFlagOptions?.selectors);
-        for (const selector of featureFlagSelectors) {
+        for (const selector of this.#featureFlagSelectors) {
+            const pageEtags = selector.pages ? Array.from(selector.pages.keys()) : undefined;
             const listOptions: ListConfigurationSettingsOptions = {
                 keyFilter: `${featureFlagPrefix}${selector.keyFilter}`,
-                labelFilter: selector.labelFilter
+                labelFilter: selector.labelFilter,
+                pageEtags: pageEtags
             };
-            const settings = listConfigurationSettingsWithTrace(
+
+            const pageIterator = listConfigurationSettingsWithTrace(
                 this.#requestTraceOptions,
                 this.#client,
                 listOptions
-            );
-            for await (const setting of settings) {
-                if (isFeatureFlag(setting)) {
-                    featureFlagsMap.set(setting.key, setting.value);
+            ).byPage();
+            const newPages = new Map<string, any[]>();
+            for await (const page of pageIterator) {
+                if (page._response.status === 200) {
+                    if (page.etag) {
+                        newPages.set(page.etag, page.items);
+                    }
+                } else if (page._response.status === 304) {
+                    if (page.etag) {
+                        // No change, keep the existing page
+                        const existingPage = selector.pages?.get(page.etag);
+                        if (existingPage) {
+                            newPages.set(page.etag, existingPage);
+                        }
+                    }
+                } else {
+                    // TODO: any other cases? deletion?
+                }
+            }
+            selector.pages = newPages;
+
+            for (const page of selector.pages.values()) {
+                for (const setting of page) {
+                    if (isFeatureFlag(setting)) {
+                        featureFlagsMap.set(setting.key, setting.value);
+                    }
                 }
             }
         }