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import type { Logger } from '../../logger/definition.ts';
import type { OnEvent } from '../../notifier/definition.ts';
/**
* A tracker for monitoring promises, providing centralized waiting, event notifications, and timing metrics.
*
* This tracker is designed for scenarios where you need to coordinate multiple unrelated promises - such as a server
* waiting for various background operations to complete before shutdown, or monitoring promise performance across
* different parts of an application.
*
* The tracker maintains an internal set of unsettled promises and provides real-time notifications when promises
* resolve or reject. It supports both direct promises and promise suppliers (functions that return promises).
*
* @example Basic usage with direct promises
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
*
* // Track some promises
* const result1 = tracker.track(fetchUser(id), 'fetch-user');
* const result2 = tracker.track(saveData(data), 'save-data');
*
* // Wait for all tracked promises to settle
* await tracker.wait();
* console.log('All operations complete');
* ```
*
* @example Server shutdown coordination
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
* import { withTimeout } from 'emitnlog/utils';
*
* const tracker = trackPromises({ logger: serverLogger });
*
* // Track various background operations
* tracker.track(dbConnection.close(), 'db-close');
* tracker.track(cache.flush(), 'cache-flush');
* tracker.track(analytics.send(), 'analytics-send');
*
* // Graceful shutdown with timeout
* await withTimeout(tracker.wait(), 5000);
* ```
*
* @example Using promise suppliers
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
*
* // Timing starts when the supplier is called, not when track() is called
* const result = await tracker.track(async () => {
* await expensiveAsyncOperation1();
* await expensiveAsyncOperation2();
* }, 'expensive-combined-op');
* ```
*
* @example Monitoring promise performance
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
*
* tracker.onSettled((event) => {
* console.log(`${event.label}: ${event.duration}ms ${event.rejected ? 'FAILED' : 'SUCCESS'}`);
* });
*
* tracker.track(apiCall(), 'api-call');
* ```
*/
export type PromiseTracker = {
/**
* The number of currently unsettled tracked promises.
*
* Returns 0 after `wait()` completes and no additional promises have been tracked.
*
* @example
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
* console.log(tracker.size); // 0
*
* tracker.track(slowOperation);
* console.log(tracker.size); // 1
*
* await tracker.wait();
* console.log(tracker.size); // 0
* ```
*/
readonly size: number;
/**
* Tracks the lifecycle of a promise or promise supplier, returning the same promise for chaining.
*
* Accepts either a direct promise or a function that returns a promise (supplier). Using a supplier provides more
* accurate timing measurements since the duration is calculated from when the supplier is invoked rather than when
* `track()` is called.
*
* The tracked promise is automatically removed from the tracker when it settles (resolves or rejects). Labels are
* optional but recommended for debugging and monitoring purposes.
*
* @example Tracking direct promises
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
* const result = await tracker.track(fetch('/api/data'), 'api-fetch');
* ```
*
* @example Tracking promise suppliers for accurate timing
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
* const result = await tracker.track(() => processLargeDataset(data), 'data-processing');
* ```
*
* @param promise A promise to track, or a function that returns a promise (supplier)
* @param label Optional label for identification in events and logs
* @returns The same promise for chaining
*/
track<T>(promise: Promise<T> | (() => Promise<T>)): Promise<T>;
track<T>(label: string, promise: Promise<T> | (() => Promise<T>)): Promise<T>;
/**
* Waits for all currently tracked promises to settle (resolve or reject).
*
* This method takes a snapshot of currently tracked promises and waits for them to complete. Promises that are
* tracked after `wait()` begins are not included in the current wait operation - this allows for predictable
* coordination patterns.
*
* Calling `wait()` when no promises are tracked returns immediately. This can be used as a way to "clear" or verify
* the tracker state.
*
* Consider using `withTimeout()` utility to prevent indefinite waiting in production scenarios.
*
* @example Server shutdown coordination
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
*
* // Start background operations
* tracker.track(backgroundJob1());
* tracker.track(backgroundJob2());
*
* // Wait for current operations to complete
* await tracker.wait();
*
* // Any new promises tracked during wait() are not included above
* tracker.track(newOperation()); // This won't block the previous wait()
* ```
*
* @example With timeout protection
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
* import { withTimeout } from 'emitnlog/utils';
*
* const tracker = trackPromises();
* tracker.track(longRunningOperation());
*
* // Wait maximum 30 seconds
* await withTimeout(tracker.wait(), 30000);
* ```
*
* @example Clearing/verifying tracker state
*
* ```ts
* const tracker = trackPromises();
*
* // This returns immediately if no promises are tracked
* await tracker.wait(); // Effectively a no-op that can verify empty state
* ```
*
* @returns A promise that resolves when all tracked promises have settled
*/
readonly wait: () => Promise<void>;
/**
* Registers event listeners for promise settlement notifications.
*
* Events are emitted in real-time when tracked promises resolve or reject, providing detailed information about
* timing, results, and labels. Multiple listeners can be registered and will all receive events.
*
* The event data includes duration measurements, optional labels, success/failure status, and result values (for
* successful resolutions). This enables performance monitoring, debugging, and custom logging.
*
* @example Performance monitoring
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
*
* tracker.onSettled((event) => {
* const status = event.rejected ? 'FAILED' : 'SUCCESS';
* const label = event.label ?? 'unlabeled';
* console.log(`${label}: ${event.duration}ms - ${status}`);
* });
* ```
*
* @example Custom metrics collection
*
* ```ts
* const metrics = { total: 0, failed: 0, avgDuration: 0 };
*
* tracker.onSettled((event) => {
* metrics.total++;
* if (event.rejected) metrics.failed++;
* metrics.avgDuration = (metrics.avgDuration + event.duration) / metrics.total;
* });
* ```
*
* @param listener Function called when any tracked promise settles
*/
readonly onSettled: OnEvent<PromiseSettledEvent>;
};
/**
* A specialized implementation of the Promise Tracker that (transiently) caches async operations by ID, ensuring each
* operation runs only once _while_ its returned promise is not settled.
*
* PromiseHolder is ideal when you need to prevent duplicate expensive operations, such as API calls, database queries,
* or file system operations. Unlike PromiseTracker which focuses on coordination and monitoring, PromiseHolder
* emphasizes operation deduplication and caching.
*
* The holder maintains a cache of ongoing operations by their unique IDs - in other words, the cache happens while the
* promise is not settled. When the same ID is requested multiple times, the holder returns the same promise, ensuring
* the underlying operation executes only once. The cache is automatically cleaned up when operations complete.
*
* When to use PromiseHolder vs PromiseTracker:
*
* - Use PromiseHolder for caching expensive operations that might be requested multiple times
* - Use PromiseTracker for coordinating multiple different operations (like shutdown procedures), when there is no reason
* to identify an operation, or to track actual promises instead of operations.
*
* @example Basic caching of API calls
*
* ```ts
* import { holdPromises } from 'emitnlog/tracker';
*
* const holder = holdPromises();
*
* // First call executes the API request
* const user1 = holder.track('user-123', () => fetchUserFromAPI(123));
*
* // Second call returns the same promise, no duplicate API call
* const user2 = holder.track('user-123', () => fetchUserFromAPI(123));
*
* console.log(user1 === user2); // true - same promise instance
* ```
*
* @example Database query deduplication
*
* ```ts
* import { holdPromises } from 'emitnlog/tracker';
*
* const queryHolder = holdPromises({ logger: dbLogger });
*
* // Multiple components request the same data simultaneously
* const results = await Promise.all([
* queryHolder.track('product-456', () => db.query('SELECT * FROM products WHERE id = 456')),
* queryHolder.track('product-456', () => db.query('SELECT * FROM products WHERE id = 456')),
* queryHolder.track('product-456', () => db.query('SELECT * FROM products WHERE id = 456')),
* ]);
* // Only one database query was executed, but all components get the result
* ```
*
* @example File system operation caching
*
* ```ts
* import { holdPromises } from 'emitnlog/tracker';
*
* const fileHolder = holdPromises();
*
* // Cache expensive file operations
* const processFile = async (filename: string) => {
* return fileHolder.track(`process-${filename}`, async () => {
* const content = await fs.readFile(filename, 'utf8');
* return processLargeFile(content); // Expensive operation
* });
* };
*
* // Multiple calls to processFile with same filename will reuse the result
* const result1 = await processFile('large-data.json');
* const result2 = await processFile('large-data.json'); // Uses cached promise
* ```
*
* @example Configuration loading with fallback
*
* ```ts
* import { holdPromises } from 'emitnlog/tracker';
*
* const configHolder = holdPromises();
*
* const getConfig = (env: string) => {
* return configHolder.track(`config-${env}`, async () => {
* try {
* return await loadConfigFromRemote(env);
* } catch {
* return loadDefaultConfig();
* }
* });
* };
* ```
*/
export type PromiseHolder = Simplify<
Omit<PromiseTracker, 'track' | 'wait'> & {
/**
* Caches and tracks an async operation by its unique ID, ensuring it runs only once per ID.
*
* When called with an ID that's already cached, returns the existing promise without executing the supplier again.
* When called with a new ID, executes the supplier function and caches the resulting promise.
*
* The cache is automatically cleaned up when the operation settles (resolves or rejects), allowing the same ID to
* be used again for future operations.
*
* Operations are tracked with the same monitoring capabilities as PromiseTracker, including timing measurements and
* event notifications.
*
* Clients are expected to ensure that the id is unique based on the nature of the operation: for example, in some
* cases the id may refer to operation itself, in others it may need to be augmented with argument information.
*
* @example API call deduplication
*
* ```ts
* import { holdPromises } from 'emitnlog/tracker';
*
* const holder = holdPromises();
*
* // These calls happen simultaneously from different parts of the app
* const [result1, result2, result3] = await Promise.all([
* holder.track('user-data', () => fetchUserProfile()),
* holder.track('user-data', () => fetchUserProfile()),
* holder.track('user-data', () => fetchUserProfile()),
* ]);
* // Only one fetchUserProfile() call was made, all get the same result
* ```
*
* @example Error handling with caching
*
* ```ts
* import { holdPromises } from 'emitnlog/tracker';
*
* const holder = holdPromises();
*
* try {
* const result = await holder.track('risky-op', () => riskyAsyncOperation());
* console.log('Success:', result);
* } catch (error) {
* console.log('Failed:', error);
* // The failed operation is removed from cache, so retry is possible
*
* // Later retry with same ID works
* const retryResult = await holder.track('risky-op', () => riskyAsyncOperation());
* }
* ```
*
* @param id Unique identifier for the operation. Operations with the same ID will be deduplicated.
* @param supplier Function that returns the promise to execute. Only called once per unique ID.
* @returns The promise from the supplier (cached or fresh)
*/
track<T>(id: string, supplier: () => Promise<T>): Promise<T>;
/**
* Checks if an operation with the given ID is currently cached (ongoing).
*
* Returns `true` if a promise with the specified ID is currently in progress. Once the operation completes
* (resolves or rejects), the cache entry is automatically removed and this method will return `false`.
*
* This method is useful for conditional logic, debugging, or monitoring cache state without triggering any
* operations.
*
* @example Conditional operation execution
*
* ```ts
* import { holdPromises } from 'emitnlog/tracker';
*
* const holder = holdPromises();
*
* if (!holder.has('expensive-calc')) {
* console.log('Starting expensive calculation...');
* } else {
* console.log('Calculation already in progress...');
* }
*
* const result = await holder.track('expensive-calc', () => performCalculation());
* ```
*
* @example Cache monitoring
*
* ```ts
* import { holdPromises } from 'emitnlog/tracker';
*
* const holder = holdPromises();
*
* // Start some operations
* holder.track('op1', () => longRunningTask1());
* holder.track('op2', () => longRunningTask2());
*
* console.log(`Active operations: op1=${holder.has('op1')}, op2=${holder.has('op2')}`);
* ```
*
* @param id The operation ID to check
* @returns True if the operation is currently cached/ongoing, false otherwise
*/
readonly has: (id: string) => boolean;
/**
* Waits for currently tracked promises to settle (resolve or reject). If no `id` is specified, all promises are
* waited, otherwise only the identified promises are waited - ids that don't match tracked promises are ignored.
*
* This method takes a snapshot of currently tracked promises and waits for them to complete. Promises that are
* tracked after `wait()` begins are not included in the current wait operation - this allows for predictable
* coordination patterns.
*
* Calling `wait()` when no promises are tracked returns immediately. This can be used as a way to "clear" or verify
* the tracker state.
*
* Consider using `withTimeout()` utility to prevent indefinite waiting in production scenarios.
*
* @example Server shutdown coordination
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
*
* const tracker = trackPromises();
*
* // Start background operations
* tracker.track('op1', () => backgroundJob1());
* tracker.track('op2', () => backgroundJob2());
*
* // Wait for all current operations to complete
* await tracker.wait();
*
* // Any new promises tracked during wait() are not included above
* tracker.track('op3', () => newOperation()); // This won't block the previous wait()
* ```
*
* @example With timeout protection and specific ids
*
* ```ts
* import { trackPromises } from 'emitnlog/tracker';
* import { withTimeout } from 'emitnlog/utils';
*
* const tracker = trackPromises();
* tracker.track('op1', () => longRunningTask1());
* tracker.track('op2', () => longRunningTask2());
*
* // Wait maximum 30 seconds for 'op2'
* await withTimeout(tracker.wait('op2'), 30000);
* ```
*
* @example Clearing/verifying tracker state
*
* ```ts
* const tracker = trackPromises();
*
* // This returns immediately if no promises are tracked
* await tracker.wait(); // Effectively a no-op that can verify empty state
* ```
*
* @returns A promise that resolves when all tracked promises have settled
*/
readonly wait: (...ids: readonly string[]) => Promise<void>;
}
>;
/**
* A persistent caching implementation of PromiseHolder that retains settled promises until manually cleared.
*
* PromiseVault provides long-term caching of expensive operations that don't change frequently, such as configuration
* loading, initialization routines, or API calls for static data. Unlike PromiseHolder which automatically clears
* cached promises when they settle, PromiseVault maintains the cache indefinitely until explicitly cleared.
*
* This is particularly useful for:
*
* - Application initialization that should happen only once
* - Configuration loading that remains valid for the application lifetime
* - Expensive computations with results that don't change
* - API calls for static or rarely-changing data
*
* **Cache Management:**
*
* - Promises remain cached even after settlement (success or failure)
* - Manual control via `clear()` to empty entire cache or `forget()` for specific entries
* - Failed operations can be automatically cleared with `forgetOnRejection` option, or manually with `forget()`
*
* **Comparison with other promise utilities:**
*
* - `PromiseTracker`: Coordination and monitoring, no caching
* - `PromiseHolder`: Transient caching during promise lifecycle only
* - `PromiseVault`: Persistent caching with manual lifecycle control
*
* @example Application initialization caching
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const initVault = vaultPromises({ logger: appLogger });
*
* // These expensive operations happen only once, even across multiple calls
* const initializeDatabase = () => initVault.track('database', () => setupDatabaseConnection());
* const loadConfiguration = () => initVault.track('config', () => fetchAppConfiguration());
* const setupAuthentication = () => initVault.track('auth', () => initializeAuthSystem());
*
* // Multiple components can safely call these - only first call executes
* await Promise.all([initializeDatabase(), loadConfiguration(), setupAuthentication()]);
*
* // Later in the application - these return cached results instantly
* const config = await loadConfiguration(); // Uses cached promise
* const dbConnection = await initializeDatabase(); // Uses cached promise
* ```
*
* @example Configuration management with refresh capability
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const configVault = vaultPromises({ logger: configLogger });
*
* const getConfig = (environment: string) => {
* return configVault.track(`config-${environment}`, async () => {
* console.log(`Loading config for ${environment}...`);
* return await fetchConfigFromRemote(environment);
* });
* };
*
* // Initial load
* const config1 = await getConfig('production');
*
* // Subsequent calls use cached result
* const config2 = await getConfig('production'); // No network call
*
* // Force refresh when needed
* configVault.forget('config-production');
* const freshConfig = await getConfig('production'); // New network call
* ```
*
* @example Static data caching with selective invalidation
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const dataVault = vaultPromises();
*
* // Cache expensive computations or API calls
* const getStaticData = (dataType: string) => {
* return dataVault.track(`static-${dataType}`, async () => {
* return await fetchStaticDataFromAPI(dataType);
* });
* };
*
* // Load various static data - cached indefinitely
* const countries = await getStaticData('countries');
* const currencies = await getStaticData('currencies');
* const timezones = await getStaticData('timezones');
*
* // Invalidate specific cache entries when data changes
* dataVault.forget('static-countries'); // Only countries will be re-fetched
*
* // Or clear all cached data
* dataVault.clear();
* ```
*
* @example Resource loading with error handling
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const resourceVault = vaultPromises({ logger: resourceLogger });
*
* const loadResource = async (resourceId: string) => {
* return resourceVault.track(`resource-${resourceId}`, async () => {
* const response = await fetch(`/api/resources/${resourceId}`);
* if (!response.ok) {
* throw new Error(`Failed to load resource: ${response.status}`);
* }
* return response.json();
* });
* };
*
* // Handle errors and retries
* try {
* const resource = await loadResource('important-data');
* } catch (error) {
* console.error('Resource load failed:', error);
*
* // Remove failed attempt from cache to allow retry
* resourceVault.forget('resource-important-data');
*
* // Retry with fresh attempt
* const resource = await loadResource('important-data');
* }
* ```
*
* @example Automatic retry on failure with forgetOnRejection
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* // Vault that automatically clears failed operations for retry
* const retryVault = vaultPromises({ logger: apiLogger, forgetOnRejection: true });
*
* const fetchWithRetry = async (url: string) => {
* return retryVault.track(`fetch-${url}`, async () => {
* const response = await fetch(url);
* if (!response.ok) {
* throw new Error(`HTTP ${response.status}: ${response.statusText}`);
* }
* return response.json();
* });
* };
*
* // First call fails and is automatically removed from cache
* try {
* await fetchWithRetry('/api/data');
* } catch (error) {
* console.log('First attempt failed');
* }
*
* // Second call executes fresh attempt (not cached)
* try {
* const data = await fetchWithRetry('/api/data'); // New attempt
* console.log('Retry succeeded:', data);
* } catch (error) {
* console.log('Retry also failed');
* }
* ```
*
* @example Mixed caching strategies
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* // Cache successful results but allow retries for failures
* const smartVault = vaultPromises({ forgetOnRejection: true });
*
* const getConfigWithFallback = async (env: string) => {
* return smartVault.track(`config-${env}`, async () => {
* try {
* // Try remote config first
* return await fetchRemoteConfig(env);
* } catch (remoteError) {
* // Fall back to local config
* console.warn(`Remote config failed, using local: ${remoteError.message}`);
* return await loadLocalConfig(env);
* }
* });
* };
*
* // If remote fails, operation throws and is cleared from cache
* // If local succeeds, result is cached permanently
* const config = await getConfigWithFallback('production');
* ```
*
* @example Performance monitoring with persistent caching
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const performanceVault = vaultPromises({ logger: perfLogger });
*
* // Monitor cache hit rates
* const getCacheStats = () => {
* return {
* size: performanceVault.size,
* entries: Array.from({ length: performanceVault.size }).map((_, i) => `entry-${i}`),
* };
* };
*
* // Track performance of cached operations
* performanceVault.onSettled((event) => {
* const cacheHit = event.duration < 10; // Cached results are very fast
* console.log(`${event.label}: ${event.duration}ms (${cacheHit ? 'CACHE HIT' : 'CACHE MISS'})`);
* });
*
* const expensiveOperation = (id: string) => {
* return performanceVault.track(`operation-${id}`, async () => {
* // Simulate expensive operation
* await new Promise((resolve) => setTimeout(resolve, 1000));
* return `Result for ${id}`;
* });
* };
*
* // First call: cache miss, slow
* await expensiveOperation('test'); // ~1000ms
*
* // Second call: cache hit, fast
* await expensiveOperation('test'); // ~1ms
* ```
*
* @example Graceful cache invalidation patterns
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const cacheVault = vaultPromises();
*
* // Time-based invalidation
* const cacheTimestamps = new Map<string, number>();
* const CACHE_TTL = 5 * 60 * 1000; // 5 minutes
*
* const getWithTTL = async (key: string, fetcher: () => Promise<any>) => {
* const now = Date.now();
* const timestamp = cacheTimestamps.get(key);
*
* if (timestamp && now - timestamp > CACHE_TTL) {
* cacheVault.forget(key);
* cacheTimestamps.delete(key);
* }
*
* if (!cacheVault.has(key)) {
* cacheTimestamps.set(key, now);
* }
*
* return cacheVault.track(key, fetcher);
* };
*
* // Usage with automatic TTL
* const data = await getWithTTL('user-settings', () => fetchUserSettings());
* ```
*/
export type PromiseVault = PromiseHolder & {
/**
* Caches and tracks an async operation with configurable persistence behavior.
*
* Extends PromiseHolder's caching functionality with optional per-operation control over cache persistence. By
* default, promises remain cached even after settlement (standard PromiseVault behavior). When the `forget` option is
* enabled, the operation behaves like PromiseHolder - automatically clearing the cache entry when the promise
* settles.
*
* This provides fine-grained control over caching strategy, allowing you to mix persistent and transient caching
* within the same vault instance based on the specific needs of each operation.
*
* @example Default persistent caching
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* // Standard behavior - promise cached indefinitely
* await vault.track('config', () => loadConfiguration());
* await vault.track('config', () => loadConfiguration()); // Uses cached promise
* ```
*
* @example Transient caching with forget option
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* // First call executes and caches temporarily
* await vault.track('temp-data', () => fetchTemporaryData(), { forget: true });
*
* // Second call executes again (cache was cleared after first completion)
* await vault.track('temp-data', () => fetchTemporaryData(), { forget: true });
* ```
*
* @example Mixed caching strategies
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* // Persistent cache for stable configuration
* const config = await vault.track('app-config', () => loadAppConfig());
*
* // Transient cache for time-sensitive data
* const liveData = await vault.track('live-feed', () => fetchLiveFeed(), { forget: true });
*
* // User-specific data that should be cached persistently
* const userData = await vault.track(`user-${userId}`, () => fetchUserData(userId));
*
* // Temporary computations that shouldn't persist
* const tempResult = await vault.track(`calc-${requestId}`, () => performCalculation(), { forget: true });
* ```
*
* @example Dynamic cache behavior based on conditions
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* const fetchData = async (id: string, isTemporary: boolean) => {
* return vault.track(`data-${id}`, () => expensiveFetchOperation(id), { forget: isTemporary });
* };
*
* // Persistent caching for important data
* await fetchData('critical-config', false);
*
* // Transient caching for temporary requests
* await fetchData('temp-analysis', true);
* ```
*
* @example Session-based caching with cleanup
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* const getSessionData = async (sessionId: string, persistent: boolean = false) => {
* return vault.track(`session-${sessionId}`, () => loadSessionFromDatabase(sessionId), {
* forget: !persistent,
* });
* };
*
* // Short-lived session data (cleared after use)
* await getSessionData('temp-session-123', false);
*
* // Long-lived session data (cached until manual cleanup)
* await getSessionData('permanent-session-456', true);
* ```
*
* @example Error handling with different cache strategies
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* const robustFetch = async (url: string, cacheFailures: boolean = false) => {
* try {
* return await vault.track(
* `fetch-${url}`,
* async () => {
* const response = await fetch(url);
* if (!response.ok) throw new Error(`HTTP ${response.status}`);
* return response.json();
* },
* { forget: !cacheFailures },
* );
* } catch (error) {
* if (!cacheFailures) {
* // For transient operations, failed attempts are automatically cleared
* console.log('Failed attempt cleared, retry available');
* } else {
* // For persistent operations, manually clear to allow retry
* vault.forget(`fetch-${url}`);
* console.log('Failed attempt manually cleared');
* }
* throw error;
* }
* };
*
* // Don't cache failures - automatic retry capability
* await robustFetch('/api/temporary-data', false);
*
* // Cache everything including failures - manual retry control
* await robustFetch('/api/critical-data', true);
* ```
*
* @param id Unique identifier for the operation. Operations with the same ID will be deduplicated.
* @param supplier Function that returns the promise to execute. Only called once per unique ID (unless cache is
* cleared).
* @param options Configuration options for this specific operation
* @param options.forget When true, automatically removes the cached promise when it settles, making this operation
* behave like PromiseHolder. When false or undefined (default), uses standard PromiseVault persistence behavior.
* @returns The promise from the supplier (cached or fresh)
*/
track<T>(id: string, supplier: () => Promise<T>, options?: { forget?: boolean }): Promise<T>;
/**
* Clears all cached promises from the vault.
*
* After calling this method, all subsequent `track()` calls will execute their suppliers regardless of whether they
* were previously cached. This is useful for global cache invalidation or cleanup scenarios.
*
* @example Global cache reset
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* // Cache some operations
* await vault.track('config', () => loadConfig());
* await vault.track('data', () => loadData());
*
* console.log(vault.size); // 2
*
* // Clear all cached entries
* vault.clear();
*
* console.log(vault.size); // 0
*
* // Next calls will execute suppliers again
* await vault.track('config', () => loadConfig()); // Executes loadConfig()
* ```
*/
clear(): void;
/**
* Removes a specific cached promise from the vault.
*
* This allows selective invalidation of cache entries. The next `track()` call with the same ID will execute the
* supplier again instead of returning the cached promise.
*
* @example Selective cache invalidation
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* // Cache some operations
* await vault.track('user-123', () => fetchUser(123));
* await vault.track('user-456', () => fetchUser(456));
*
* // Invalidate specific user
* const wasRemoved = vault.forget('user-123');
* console.log(wasRemoved); // true
*
* // user-123 will be fetched again, user-456 uses cached version
* await vault.track('user-123', () => fetchUser(123)); // Executes fetchUser(123)
* await vault.track('user-456', () => fetchUser(456)); // Uses cached promise
* ```
*
* @example Error recovery
*
* ```ts
* import { vaultPromises } from 'emitnlog/tracker';
*
* const vault = vaultPromises();
*
* try {
* await vault.track('risky-op', () => riskyOperation());
* } catch (error) {
* // Remove failed operation from cache to allow retry
* vault.forget('risky-op');
*
* // Retry will execute the operation again
* await vault.track('risky-op', () => riskyOperation());
* }
* ```
*
* @param id The ID of the cached promise to remove
* @returns True if the entry was found and removed, false if it wasn't in the cache
*/
forget(id: string): boolean;
};
/**
* Event data emitted when a tracked promise settles (resolves or rejects).
*
* This event provides comprehensive information about the promise lifecycle, including timing data, optional labeling,
* success/failure status, and result values. The duration measurement starts from when `track()` is invoked, or more
* accurately, from when a promise supplier function is called.
*/
export type PromiseSettledEvent = {
/**
* Optional label provided when tracking the promise.
*
* Labels help identify specific promises in logs and event handlers, especially useful when tracking multiple
* promises of the same type.
*/
readonly label?: string;
/**
* Duration of the promise lifecycle in milliseconds.
*
* For direct promises, timing starts when `track()` is called. For promise suppliers (functions), timing starts when
* the supplier function is invoked, providing more accurate measurements of the actual async operation duration.
*
* @example
*
* ```ts
* // Less accurate - includes time between track() call and promise creation
* tracker.track(someAsyncFunction(), 'operation');
*
* // More accurate - measures only the async operation itself
* tracker.track(() => someAsyncFunction(), 'operation');
* ```
*/
readonly duration: number;
/**
* Indicates whether the promise was rejected.
*
* When `true`, the promise rejected with an error. When `false` or undefined, the promise resolved successfully.
*/
readonly rejected?: boolean;
/**
* The result of the promise, either the resolved or rejected value.
*/
readonly result?: unknown;
};
/**
* Options for configuring a PromiseTracker.
*/
export type PromiseTrackerOptions = { readonly logger?: Logger };
/**
* Options for configuring a PromiseVault.
*/
export type PromiseVaultOptions = { readonly forgetOnRejection?: boolean } & PromiseTrackerOptions;
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