Cache Dart Reference Documentation

CkCache

Current Version: 11.6.1

Chilkat.Cache

Store, retrieve, expire, and clean up cached text or binary data on disk.

Chilkat.Cache is a disk-based cache class for storing and retrieving text or binary items by unique key. It provides configurable cache roots, optional multi-level directory layout, expiration metadata, ETag metadata, cache lookup, fetch-status properties, expiration updates, and cleanup methods for deleting individual items, expired items, older items, or the entire cache.

Key-based storage

Store and retrieve cached items by unique key, without the application needing to manage the underlying cache filenames directly.

Text and binary data

Cache strings, byte data, files, or Chilkat buffer objects depending on the data form used by the application.

Expiration control

Associate cached items with expiration times, update expiration metadata, and check whether cached content is still usable.

ETag metadata

Store and retrieve ETag values for workflows that need HTTP-style cache validation or conditional re-fetch logic.

Configurable layout

Choose the cache root directory and use an optional multi-level directory structure to avoid too many files in a single folder.

Cleanup operations

Delete a single cached item, remove expired items, remove older items, or clear the entire cache when needed.

Common pattern: Configure the cache root, choose the key used to identify each item, check whether a valid cached copy exists, fetch or regenerate the content when needed, store it with expiration and optional ETag metadata, and periodically clean up expired or old cached items.

For an extended overview, see Cache Class Overview.

Object Creation

// pubspec.yaml:
//     dependencies:
//       chilkat: ^11.6.1

import 'package:chilkat/chilkat.dart';

// Once per process, before any other Chilkat call:
Chilkat.unlockBundle('Anything for 30-day trial');   // shorthand for CkGlobal().unlockBundle(..)

final cache = CkCache();
// ... the native object is released when `cache` is garbage collected, or now with cache.dispose().

CkCache CkCache()

Creates the underlying native Chilkat object. Use a CkCache only from the isolate that created it: Chilkat objects cannot be sent between isolates. Every call is synchronous; in a Flutter app, run long operations (network, large files) inside Isolate.run, creating the Chilkat objects inside the isolate.

void dispose()

Releases the native object immediately instead of waiting for garbage collection (useful for a large CkBinData or an open socket). Calling it more than once is harmless; any other use of the object afterwards throws a StateError. isDisposed tells whether it has been called.

Errors

A method that can fail throws a ChilkatException: a method whose only outcome is success or failure returns void and throws on failure; a method producing a String or an object returns it and throws where Chilkat would have returned null. The exception carries the object's LastErrorText at the time of the failure (lastErrorText), the class and method names (className, methodName) and a one-line message. Properties never throw, and methods that answer a question (has..., is..., ...) return a plain bool.

try {
  cache.someMethod(...);
} on ChilkatException catch (e) {
  print(e);                // CkCache.someMethod failed: <reason>
  print(e.lastErrorText);  // the full Chilkat log of the failed call
}

Properties

DebugLogFilePath

// read/write
String get debugLogFilePath
set debugLogFilePath(String value)

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

A timeout property set to 0, indicating an infinite timeout.
A hang occurring within an event callback in the application code.
An internal bug in the Chilkat code causing the hang.

More Information and Examples

Value	Directory layout
`0`	All cache files are stored directly in the cache root.
`1`	Files are distributed among 256 first-level directories named `0` through `255`.
`2`	Files are distributed through two levels of 256 directories, allowing as many as 65,536 leaf directories per root.

Return value	Meaning
`true`	The item was deleted, or no item existed for the key.
`false`	The item exists but could not be deleted, for example because of a filesystem permission or sharing error.

Argument	Purpose
`key`	The unique application-defined cache key.
`expiration`	Expiration as an RFC 822-style Internet date string. Pass an empty string for no expiration.
`etag`	Optional ETag or application metadata. Pass an empty string when unused.
`bd`	The `BinData` containing the bytes to save.

Cache Dart Reference Documentation

CkCache

Current Version: 11.6.1

Store, retrieve, expire, and clean up cached text or binary data on disk.

Key-based storage

Text and binary data

Expiration control

ETag metadata

Configurable layout

Cleanup operations

Object Creation

Errors

Properties

DebugLogFilePath

LastErrorHtml

LastErrorText

LastErrorXml

LastEtagFetched

LastExpirationFetchedStr

LastHitExpired

LastKeyFetched

LastMethodSuccess

Level

NumRoots

VerboseLogging

Version

Methods

AddRoot

DeleteAll

DeleteAllExpired

DeleteFromCache

DeleteOlderDt

DeleteOlderStr

FetchBd

FetchSb

FetchText

GetEtag

GetExpirationStr

GetFilename

GetRoot

IsCached

SaveBd

SaveTextDt

SaveTextNoExpire

SaveTextStr

UpdateExpirationDt

UpdateExpirationStr