Cache Delphi DLL Reference Documentation

Cache

Current Version: 10.1.2

Requires Chilkat Bundle License

Create/Dispose

var
myObject: HCkCache;

begin
myObject := CkCache_Create();

// ...

CkCache_Dispose(myObject);
end;

function CkCache_Create: HCkCache; stdcall;

Creates an instance of the HCkCache object and returns a handle (i.e. a Pointer). The handle is passed in the 1st argument for the functions listed on this page.

procedure CkCache_Dispose(handle: HCkCache); stdcall;

Objects created by calling CkCache_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function.

Properties

DebugLogFilePath

procedure CkCache_getDebugLogFilePath(objHandle: HCkCache; outPropVal: HCkString); stdcall;
procedure CkCache_putDebugLogFilePath(objHandle: HCkCache; newPropVal: PWideChar); stdcall;
function CkCache__debugLogFilePath(objHandle: HCkCache): PWideChar; stdcall;

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.

See the notes about PWideChar memory ownership and validity.

More Information and Examples

Example showing how to use DebugLogFilePath.

LastErrorHtml

procedure CkCache_getLastErrorHtml(objHandle: HCkCache; outPropVal: HCkString); stdcall;
function CkCache__lastErrorHtml(objHandle: HCkCache): PWideChar; stdcall;

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

See the notes about PWideChar memory ownership and validity.

LastErrorText

procedure CkCache_getLastErrorText(objHandle: HCkCache; outPropVal: HCkString); stdcall;
function CkCache__lastErrorText(objHandle: HCkCache): PWideChar; stdcall;

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

See the notes about PWideChar memory ownership and validity.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

LastErrorXml

procedure CkCache_getLastErrorXml(objHandle: HCkCache; outPropVal: HCkString); stdcall;
function CkCache__lastErrorXml(objHandle: HCkCache): PWideChar; stdcall;

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

See the notes about PWideChar memory ownership and validity.

LastEtagFetched

procedure CkCache_getLastEtagFetched(objHandle: HCkCache; outPropVal: HCkString); stdcall;
function CkCache__lastEtagFetched(objHandle: HCkCache): PWideChar; stdcall;

The ETag of the last item fetched from cache.

See the notes about PWideChar memory ownership and validity.

LastExpirationFetchedStr

procedure CkCache_getLastExpirationFetchedStr(objHandle: HCkCache; outPropVal: HCkString); stdcall;
function CkCache__lastExpirationFetchedStr(objHandle: HCkCache): PWideChar; stdcall;

Expiration date/time of the last item fetched from cache in RFC822 string format.

See the notes about PWideChar memory ownership and validity.

LastHitExpired

function CkCache_getLastHitExpired(objHandle: HCkCache): wordbool; stdcall;

True if the LastExpirationFetched is before the current date/time. Otherwise False.

LastKeyFetched

procedure CkCache_getLastKeyFetched(objHandle: HCkCache; outPropVal: HCkString); stdcall;
function CkCache__lastKeyFetched(objHandle: HCkCache): PWideChar; stdcall;

The key of the last item fetched from cache. (For web pages, the key is typically the canonicalized URL. Otherwise, the key is a unique identifer used to access the cached item.)

See the notes about PWideChar memory ownership and validity.

LastMethodSuccess

function CkCache_getLastMethodSuccess(objHandle: HCkCache): wordbool; stdcall;
procedure CkCache_putLastMethodSuccess(objHandle: HCkCache; newPropVal: wordbool); stdcall;

Indicates the success or failure of the most recent method call: True means success, False means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.

Level

function CkCache_getLevel(objHandle: HCkCache): Integer; stdcall;
procedure CkCache_putLevel(objHandle: HCkCache; newPropVal: Integer); stdcall;

The number of directory levels in the cache. Possible values are:

0: All cache files are in a single directory (the cache root).

1: Cache files are located in 256 sub-directories numbered 0 .. 255 directly under the cache root.

2: There are two levels of sub-directories under the cache root. The 1st level has 256 sub-directories numbered 0 .. 255 directly under the cache root. The 2nd level allows for up to 256 sub-directories (0..255) under each level-1 directory. Cache files are stored in the leaf directories.

NumRoots

function CkCache_getNumRoots(objHandle: HCkCache): Integer; stdcall;

The number of root directories composing the cache. A typical multi-root cache would place each root on a separate hard drive.

VerboseLogging

function CkCache_getVerboseLogging(objHandle: HCkCache): wordbool; stdcall;
procedure CkCache_putVerboseLogging(objHandle: HCkCache; newPropVal: wordbool); stdcall;

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

Version

procedure CkCache_getVersion(objHandle: HCkCache; outPropVal: HCkString); stdcall;
function CkCache__version(objHandle: HCkCache): PWideChar; stdcall;

Version of the component/library, such as "10.1.0"

See the notes about PWideChar memory ownership and validity.

More Information and Examples

How to get the Chilkat version at runtime.

Methods

AddRoot

procedure CkCache_AddRoot(objHandle: HCkCache;
path: PWideChar) stdcall;

Must be called once for each cache root. For example, if the cache is spread across D:\cacheRoot, E:\cacheRoot, and F:\cacheRoot, an application would setup the cache object by calling AddRoot three times -- once with "D:\cacheRoot", once with "E:\cacheRoot", and once with "F:\cacheRoot".

More Information and Examples

Large Persistent Hash Table Stored on Filesystem

DeleteAll

function CkCache_DeleteAll(objHandle: HCkCache): Integer; stdcall;

Deletes all items in the cache. This method completely clears the cache. All files in the cache are deleted. (If the cache is multi-level, existing sub-directories are not deleted.)

Returns the number of items (i.e. cache files) deleted.

DeleteAllExpired

function CkCache_DeleteAllExpired(objHandle: HCkCache): Integer; stdcall;

Deletes all expired items from the cache.

Returns the number of items (i.e. cache files) deleted.

DeleteFromCache

function CkCache_DeleteFromCache(objHandle: HCkCache;
key: PWideChar): wordbool; stdcall;

Deletes a single item from the disk cache. Returns False if the item exists in cache but could not be deleted. Otherwise returns True.

Returns True for success, False for failure.

DeleteOlderDt

function CkCache_DeleteOlderDt(objHandle: HCkCache;
dateTime: HCkDateTime): Integer; stdcall;

The same as DeleteOlder, except the dateTime is passed as a CkDateTime.

DeleteOlderStr

function CkCache_DeleteOlderStr(objHandle: HCkCache;
dateTimeStr: PWideChar): Integer; stdcall;

The same as DeleteOlder, except the dateTimeStr is passed as a date/time in RFC822 format.

FetchBd

function CkCache_FetchBd(objHandle: HCkCache;
key: PWideChar;
bd: HCkBinData): wordbool; stdcall;

Introduced in version 9.5.0.91

Fetches an item from cache and returns in bd.

The key may be any length and may include any characters. It should uniquely identify the cached item. (No two items in the cache should have the same key.)

Returns True for success, False for failure.

FetchFromCache

function CkCache_FetchFromCache(objHandle: HCkCache;
key: PWideChar;
outBytes: HCkByteData): wordbool; stdcall;

Fetches an item from cache.

The key may be any length and may include any characters. It should uniquely identify the cached item. (No two items in the cache should have the same key.)

Returns True for success, False for failure.

FetchSb

function CkCache_FetchSb(objHandle: HCkCache;
key: PWideChar;
sb: HCkStringBuilder): wordbool; stdcall;

Introduced in version 9.5.0.91

Fetches a text item from the cache and returns in sb.

The key may be any length and may include any characters. It should uniquely identify the cached item. (No two items in the cache should have the same key.)

Returns True for success, False for failure.

FetchText

function CkCache_FetchText(objHandle: HCkCache;
    key: PWideChar;
    outStr: HCkString): wordbool; stdcall;
function CkCache__fetchText(objHandle: HCkCache;
    key: PWideChar): PWideChar; stdcall;

Fetches a text item from the cache and returns it's text content.

The key may be any length and may include any characters. It should uniquely identify the cached item. (No two items in the cache should have the same key.)

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

More Information and Examples

Large Persistent Hash Table Stored on Filesystem

GetEtag

function CkCache_GetEtag(objHandle: HCkCache;
    key: PWideChar;
    outStr: HCkString): wordbool; stdcall;
function CkCache__getEtag(objHandle: HCkCache;
    key: PWideChar): PWideChar; stdcall;

Returns the eTag for an item in the cache.

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

GetExpirationDt

function CkCache_GetExpirationDt(objHandle: HCkCache;
key: PWideChar): HCkDateTime; stdcall;

Returns the expiration date/time for an item in the cache as a CkDateTime object.

Returns nil on failure

GetExpirationStr

function CkCache_GetExpirationStr(objHandle: HCkCache;
    url: PWideChar;
    outStr: HCkString): wordbool; stdcall;
function CkCache__getExpirationStr(objHandle: HCkCache;
    url: PWideChar): PWideChar; stdcall;

Returns the expiration date/time for an item in the cache in RFC822 string format.

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

GetFilename

function CkCache_GetFilename(objHandle: HCkCache;
    key: PWideChar;
    outStr: HCkString): wordbool; stdcall;
function CkCache__getFilename(objHandle: HCkCache;
    key: PWideChar): PWideChar; stdcall;

Returns the absolute file path of the cache file associated with the key.

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

GetRoot

function CkCache_GetRoot(objHandle: HCkCache;
    index: Integer;
    outStr: HCkString): wordbool; stdcall;
function CkCache__getRoot(objHandle: HCkCache;
    index: Integer): PWideChar; stdcall;

Returns the directory path of the Nth cache root. (Indexing begins at 0.)

Returns True for success, False for failure.

See the notes about PWideChar memory ownership and validity.

IsCached

function CkCache_IsCached(objHandle: HCkCache;
key: PWideChar): wordbool; stdcall;

Returns True if the item is found in the cache, otherwise returns False.

SaveTextDt

function CkCache_SaveTextDt(objHandle: HCkCache;
    key: PWideChar;
    expireDateTime: HCkDateTime;
    eTag: PWideChar;
    itemTextData: PWideChar): wordbool; stdcall;

The same as SaveText, except the expire date/time is passed as a CkDateTime object.

Returns True for success, False for failure.

SaveTextNoExpire

function CkCache_SaveTextNoExpire(objHandle: HCkCache;
    key: PWideChar;
    eTag: PWideChar;
    itemTextData: PWideChar): wordbool; stdcall;

Inserts or replaces an text item in the cache with no expiration date/time. The eTag is optional and may be set to a zero-length string. Applications may use it as a place to save additional information about the cached item.

Returns True for success, False for failure.

More Information and Examples

Large Persistent Hash Table Stored on Filesystem

SaveTextStr

function CkCache_SaveTextStr(objHandle: HCkCache;
    key: PWideChar;
    expireDateTime: PWideChar;
    eTag: PWideChar;
    itemTextData: PWideChar): wordbool; stdcall;

The same as SaveText, except the expire date/time is passed as a string in RFC822 format.

Returns True for success, False for failure.

SaveToCacheDt

function CkCache_SaveToCacheDt(objHandle: HCkCache;
    key: PWideChar;
    expireDateTime: HCkDateTime;
    eTag: PWideChar;
    itemData: HCkByteData): wordbool; stdcall;

The same as SaveToCache, except the expire date/time is passed as a CkDateTime object.

Returns True for success, False for failure.

SaveToCacheNoExpire

function CkCache_SaveToCacheNoExpire(objHandle: HCkCache;
    key: PWideChar;
    eTag: PWideChar;
    itemData: HCkByteData): wordbool; stdcall;

Inserts or replaces an item in the cache. The cached item will have no expiration. The eTag is optional and may be set to a zero-length string. Applications may use it as a place to save additional information about the cached item.

Returns True for success, False for failure.

SaveToCacheStr

function CkCache_SaveToCacheStr(objHandle: HCkCache;
    key: PWideChar;
    expireDateTime: PWideChar;
    eTag: PWideChar;
    itemData: HCkByteData): wordbool; stdcall;

The same as SaveToCache, except the expire date/time is passed in RFC822 string format.

Returns True for success, False for failure.

UpdateExpirationDt

function CkCache_UpdateExpirationDt(objHandle: HCkCache;
key: PWideChar;
expireDateTime: HCkDateTime): wordbool; stdcall;

The same as UpdateExpiration, except the expireDateTime is passed as a CkDateTime.

Returns True for success, False for failure.

UpdateExpirationStr

function CkCache_UpdateExpirationStr(objHandle: HCkCache;
key: PWideChar;
expireDateTime: PWideChar): wordbool; stdcall;

The same as UpdateExpiration, except the expireDateTime is passed in RFC822 string format.

Returns True for success, False for failure.