ihttpcachekey-getisequal-method.md

title	description	ms.date	ms.assetid
IHttpCacheKey::GetIsEqual Method	The IHttpCacheKey::GetIsEqual Method returns a value that indicates whether two I H t t p Cache Key pointers are equivalent.	10/07/2016	ac83971b-5092-42c7-d20f-dba89ab5dcad

IHttpCacheKey::GetIsEqual Method

Returns a value that indicates whether two IHttpCacheKey pointers are equivalent.

Syntax

virtual bool GetIsEqual(  
   IHttpCacheKey* pCacheCompareKey  
) const = 0;  

Parameters

pCacheCompareKey
A non-NULL IHttpCacheKey pointer to compare with the current IHttpCacheKey.

Return Value

true if the current IHttpCacheKey is equivalent to the pCacheCompareKey parameter; otherwise, false.

Remarks

CGlobalModule derived classes that register for GL_CACHE_OPERATION events receive an ICacheProvider pointer as a parameter on the CGlobalModule::OnGlobalCacheOperationvirtual method. You can retrieve an IHttpCacheKey pointer by calling the ICacheProvider::GetCacheKey method on the ICacheProvider pointer. You can then compare two IHttpCacheKey pointers by calling the GetIsEqual method.

The pCacheCompareKey parameter must not be NULL; otherwise, GetIsEqual will throw an access violation. In addition, pCacheCompareKey must be the same extended interface type as the current IHttpCacheKey pointer. For example, if the current IHttpCacheKey pointer implements the IFileKey interface, the pCacheCompareKey parameter must implement IFileKey, as well.

The GetIsEqual return value depends on both interface and implementation. You should use the following information as a guideline, but it may not be correct in all scenarios:

• Classes that implement IFileKey return true only if the IFileKey::GetPath method returns equivalent values on both the current IHttpCacheKey and pCacheCompareKey pointers.

• Classes that implement the IHttpTokenKey interface return true only if the IHttpTokenKey::GetUserName and IHttpTokenKey::GetLogonMethod methods return equivalent values on both the current IHttpCacheKey and pCacheCompareKey pointers.

• Classes that implement the IUriKey interface return true only if the IUriKey::GetSiteId and IUriKey::GetUrl methods return equivalent values on both the current IHttpCacheKey and pCacheCompareKey pointers.

Example

The following code example demonstrates how to create a global module that listens for GL_CACHE_OPERATION and GL_CACHE_CLEANUP events and then writes the IHttpCacheKey and the GetIsEqual information to the Event Viewer. It also demonstrates that if the same IHttpCacheKey pointer is compared against itself, the GetIsEqual method will return true.

Caution

[!INCLUDEiisver] generates a large number of events in the Event Viewer. To avoid a log overflow error in a production environment, you should generally avoid writing cache information to the event log. For demonstration purposes, this code example writes an entry to the Event Viewer in debug mode only.

[!code-cppIHttpCacheKey#4]

The above code writes a new event to the Event Viewer, where the Data box contains a string similar to the following.

IHttpCacheKey::GetIsEqual: true  

Your module must export the RegisterModule function. You can export this function by creating a module definition (.def) file for your project, or you can compile the module by using the /EXPORT:RegisterModule switch. For more information, see Walkthrough: Creating a Request-Level HTTP Module By Using Native Code.

You can optionally compile the code by using the __stdcall (/Gz) calling convention instead of explicitly declaring the calling convention for each function.

Requirements

Type	Description
Client	- IIS 7.0 on [!INCLUDEwinvista] - IIS 7.5 on Windows 7 - IIS 8.0 on Windows 8 - IIS 10.0 on Windows 10
Server	- IIS 7.0 on [!INCLUDEwinsrv2008] - IIS 7.5 on Windows Server 2008 R2 - IIS 8.0 on Windows Server 2012 - IIS 8.5 on Windows Server 2012 R2 - IIS 10.0 on Windows Server 2016
Product	- IIS 7.0, IIS 7.5, IIS 8.0, IIS 8.5, IIS 10.0 - [!INCLUDEiisexp75], [!INCLUDEiisexp80], [!INCLUDEiisexp100]
Header	Httpserv.h

See Also

IHttpCacheKey Interface