IHttpCacheSpecificData::GetFlushed, méthode

Retourne une valeur indiquant si les données spécifiques ont été vidées du cache.

Syntaxe

virtual BOOL GetFlushed(  
   VOID  
) const = 0;  

Paramètres

Cette méthode ne prend aucun paramètre.

Valeur renvoyée

true si les données ont été vidées du cache ; sinon, false.

Cohérence de thread

Les classes qui implémentent l’interface IHttpCacheSpecificData sont thread-safe pour les GetFlushed méthodes et SetFlushed .

Remarques

Le comportement de la méthode est spécifique à l’implémentation GetFlushed . Vous devez utiliser les informations suivantes comme recommandations, mais elles peuvent ne pas être correctes dans tous les scénarios :

• Les classes qui implémentent l’interface IHttpCacheSpecificData initialisent un private indicateur booléen en false tant que variable instance lors de la construction d’un nouveau pointeur. Les classes obtiennent et définissent ensuite cet indicateur sur les GetFlushed appels suivants aux méthodes et SetFlushed , respectivement.

• Les classes qui implémentent l’interface IHttpFileInfo retournent falseGetFlushed généralement et effectuent une opération vide sur SetFlushed, car les fichiers locaux sont considérés comme toujours mis en cache.

Exemple

L’exemple de code suivant montre comment créer un module global qui écoute les événements GL_CACHE_OPERATION et GL_CACHE_CLEANUP, puis écrit les informations de vidage dans le observateur d'événements.

Attention

IIS 7 génère un grand nombre d’événements dans le observateur d'événements. Pour éviter une erreur de dépassement de journal dans un environnement de production, vous devez généralement éviter d’écrire des informations de cache dans le journal des événements. À des fins de démonstration, cet exemple de code écrit une entrée dans le observateur d'événements en mode débogage uniquement.

#pragma warning( disable : 4290 )
#pragma warning( disable : 4530 )

#define _WINSOCKAPI_
#include <windows.h>
#include <sal.h>
#include <tchar.h>
#include <initguid.h>
#include <httptrace.h>
#include <httpserv.h>
#include <httpcach.h>

#include <string>
using namespace std;

// The CConvert class mirrors the Convert class that is 
// defined in the .NET Framework. It converts primitives 
// and other data types to wstring types.
class CConvert
{
public:
    // The ToString method converts a BOOL to a wstring.
    // b: the BOOL value to convert to a wstring.
    // return: L"true" for true; otherwise, L"false" for false.
    static wstring ToString(BOOL b)
    {
        return (b) ? L"true" : L"false";
    }

    // The ToByteString converts a double-byte 
    // character string to a single-byte string.
    // str: the double-byte string to convert.
    // return: a single-byte string copied from str.
    static string ToByteString(const wstring& str)
    {
        // Get the length of the 
        // double-byte string.
        size_t length = str.length();

        // Create a temporary char pointer.
        char* byteChar = new char[length+1];
        byteChar[0] = '\0';
        // Copy the double-byte character string
        // into the single-byte string.        
        size_t charsReturned = 0;
        wcstombs_s(&charsReturned, byteChar, 
                   length+1, str.c_str(), length+1);
        // Create a string to return.
        string retString = byteChar;
        // Delete the temporary string and
        // set that string to NULL.
        delete[] byteChar;
        byteChar = NULL;

        // Return the single-byte string.
        return retString;
    }
};

// The CEventException class is 
// an exception that can be thrown 
// when writing an event fails.
class CEventException
{
public:
    // Creates the CEventException class.
    // str: the wstring that could 
    // not be written to a log.
    CEventException(const wstring& str)
        : m_string(str)
    {
        
    }

    // Creates the destructor for 
    // the CEventException class.
    virtual ~CEventException()
    {

    }

private:
    // Specify the wstring that could
    // not be written to an event viewer.
    wstring m_string;
};

// The CEventWriter class writes XML 
// documents and strings to the event log.
class CEventWriter
{
public:
    // Creates the CEventWriter class.
    // name: the name of the 
    // event log to open.
    CEventWriter(const wstring& name)
    {                
        #ifdef UNICODE
        m_eventLog = RegisterEventSource(NULL, name.c_str());
        #else
        string multiName = CConvert::ToByteString(name);
        m_eventLog = RegisterEventSource(NULL, multiName.c_str());
        #endif        
    }

    // Creates the destructor for the 
    // CEventWriter class. This destructor
    // closes the HANDLE to the event 
    // log if that HANDLE is open.
    virtual ~CEventWriter()
    {
        // If the HANDLE to the event 
        // log is open, close it.
        if (NULL != m_eventLog)
        {
            // Deregister the event log HANDLE.
            DeregisterEventSource(m_eventLog);
            // Set the HANDLE to NULL.
            m_eventLog = NULL;
        }
    }

    // The ReportInfo method writes 
    // a wstring to the event log.
    // info: the wstring to write.
    // return: true if the event log is written.
    BOOL ReportInfo(const wstring& info)
    {
        return ReportEvent(EVENTLOG_INFORMATION_TYPE, info);
    }
protected:
    // The ReportEvent method accepts an event type
    // and a wstring, and attempts to write that 
    // event to the event log.
    // type: the type of the event.
    // data: the wstring to write to the event log.
    // return: true if the event log is written;
    // otherwise, false.
    BOOL ReportEvent(WORD type, const wstring& data)
    {
        // If the m_eventLog HANDLE 
        // is NULL, return false.
        if (NULL == m_eventLog)
        {
            return FALSE;
        }

        #ifndef _DEBUG
        // If the current build is not debug,
        // return so the event log is not written.
        return TRUE;
        #endif

        #ifdef UNICODE
        // The unicode version of the ReportEvent
        // method requires double-byte strings.
        PCWSTR arr[1];
        arr[0] = data.c_str();
        return ::ReportEvent(m_eventLog,
                             type,
                             0, 0, NULL, 1, 
                             0, arr, (void*)arr);
        #else
        // The non-unicode version of the ReportEvent
        // method requires single-byte strings.
        string multiByte = 
            CConvert::ToByteString(data);
        LPCSTR arr[1];
        arr[0] = multiByte.c_str();
        return ::ReportEvent(m_eventLog,
                             type,
                             0, 0, NULL, 1,
                             0, arr, (void*)arr);
        #endif
    }
private:
    // Specify the HANDLE to the 
    // event log for writing.
    HANDLE m_eventLog;
};

// The CGlobalCacheModule class creates the CGlobalModule 
// class and registers for GL_CACHE_OPERATION and 
// GL_CACHE_CLEANUP events.
class CGlobalCacheModule : public CGlobalModule
{
public:
    // Creates the destructor for the 
    // CGlobalCacheModule class.
    virtual ~CGlobalCacheModule()
    {

    }

    // The RegisterGlobalModule method creates and registers 
    // a new CGlobalCacheModule for GL_CACHE_OPERATION and 
    // GL_CACHE_CLEANUP events.
    // dwServerVersion: the current server version.
    // pModuleInfo: the current IHttpModuleRegistrationInfo pointer.
    // pGlobalInfo: the current IHttpServer pointer.
    // return: ERROR_NOT_ENOUGH_MEMORY if the heap is out of 
    // memory; otherwise, the value from the call to the 
    // SetGlobalNotifications method on the pModuleInfo pointer.
    static HRESULT RegisterGlobalModule
    (
        DWORD dwServerVersion,
        IHttpModuleRegistrationInfo* pModuleInfo,
        IHttpServer* pGlobalInfo
    )
    {        
        // The pGlobalInfo parmeter must be non-NULL because
        // the constructor for the CGlobalCacheModule class
        // requires a non-NULL pointer to a valid IHttpServer 
        // pointer.
        if (NULL == pGlobalInfo)
        {
            return E_INVALIDARG;
        }

        // Create a new CGlobalCacheModule pointer.
        CGlobalCacheModule* traceModule = 
            new CGlobalCacheModule();

        // Return an out-of-memory error if the traceModule 
        // is NULL after the call to the new operator.
        if (NULL == traceModule)
        {            
            return HRESULT_FROM_WIN32(ERROR_NOT_ENOUGH_MEMORY);
        }        

        // Attempt to set global notification for both 
        // GL_CACHE_OPERATION and GL_CACHE_CLEANUP events 
        // by using the traceModule as a listener.
        HRESULT hr = pModuleInfo->SetGlobalNotifications
            (traceModule, GL_CACHE_OPERATION | GL_CACHE_CLEANUP);

        // If the SetGlobalNotifications method 
        // fails, return the HRESULT.
        if (FAILED(hr))
        {
            return hr;
        }

        // Set the priority to PRIORITY_ALIAS_FIRST, 
        // which will populate the data as much as possible.
        hr = pModuleInfo->SetPriorityForGlobalNotification(
            GL_CACHE_OPERATION, PRIORITY_ALIAS_FIRST);

        // Return the HRESULT from the call to 
        // the SetGlobalNotifications method.
        return hr;
    }
    // The OnGlobalCacheOperation method is called 
    // when GL_CACHE_OPERATION operations occur.
    // pProvider: the current ICacheProvider pointer.
    // return: GL_NOTIFICATION_CONTINUE if the event
    // log is written; otherwise, GL_NOTIFICATION_HANDLED.
    virtual GLOBAL_NOTIFICATION_STATUS OnGlobalCacheOperation
    (
        IN ICacheProvider* pProvider
    )
    {
        // The OnGlobalCacheOperation must return if the 
        // pProvider parameter is NULL because this pointer 
        // is needed for data to write to the event log.
        if (NULL == pProvider)
        {
            return GL_NOTIFICATION_CONTINUE;
        }

        try
        {
            // Get the IHttpCacheSpecificData pointer 
            // from the ICacheProvider element.
            IHttpCacheSpecificData* cacheSpecificData = 
                pProvider->GetCacheRecord();

            // Write the IHttpCacheSpecificData 
            // pointer information to the event log.
            Write(cacheSpecificData);
        }
        // A CEventException is thrown 
        // if any Write method cannot 
        // write to the event log.
        catch (CEventException)
        {
            return GL_NOTIFICATION_HANDLED;
        }

        // Return GL_NOTIFICATION_CONTINUE so that 
        // other listeners will receive the event.
        return GL_NOTIFICATION_CONTINUE;
    }

    // The OnGlobalCacheCleanup method is called 
    // when GL_CACHE_CLEANUP events occur.
    // return: GL_NOTIFICATION_CONTINUE.
    virtual GLOBAL_NOTIFICATION_STATUS OnGlobalCacheCleanup(VOID)
    {
        // Return GL_NOTIFICATION_CONTINUE so that 
        // other listeners will receive this event.
        return GL_NOTIFICATION_CONTINUE;
    }

    // PRE: none.
    // POST: the Terminate method calls delete on 
    // this, which releases the memory for the current 
    // CGlobalCacheModule pointer on the heap.
    virtual VOID Terminate(VOID)
    {
        delete this;
    }
protected:
    // Creates the constructor for 
    // the CGlobalCacheModule class.
    // The constructor initializes the 
    // private m_eventWriter to write 
    // to the IISADMIN event log.
    CGlobalCacheModule() : m_eventWriter(L"IISADMIN")
    {

    }

    // The ReportInfo method writes the 
    // formatted name and value of a method 
    // call to the event log.
    // name: the name of the method or property.
    // value: the value of the 
    // method or the property.
    // throws: a CEventException exception.
    void ReportInfo
    (
        const wstring& name,
        const wstring& value
    ) throw (CEventException)
    {
        // Create a formatted string to
        // write to the event log.
        wstring infoString =
            name + wstring(L":  ") + value;
        // Attempt to write the formatted 
        // string to the event log. If the 
        // ReportInfo method call fails,
        // throw a CEventException exception.
        if (!m_eventWriter.ReportInfo(infoString))
        {
            throw CEventException(infoString);
        }        
    }

    // The Write method writes IHttpCacheSpecificData
    // pointer information to the event log.
    // cacheSpecificData: the IHttpCacheSpecificData
    // pointer to write.
    // throws: a CEventException exception.
    void Write
    (
        IHttpCacheSpecificData* cacheSpecificData        
    ) throw (CEventException)
    {
        // If the cacheSpecificData is NULL, 
        // return. IHttpCacheSpecificData 
        // pointer data is optional.
        if (NULL == cacheSpecificData)
        {
            return;
        }

        // Get flushed information from the
        // IHttpCacheSpecificData pointer.
        BOOL flushedBOOL =
            cacheSpecificData->GetFlushed();

        // Convert the Boolean 
        // to a wstring.
        wstring flushed = CConvert::ToString(flushedBOOL);

        // Write the flushed information
        // to the event log.
        ReportInfo(L"IHttpCacheSpecificData::GetFlushed",
                   flushed);
    }
private:
    // Specify the event writer.
    CEventWriter m_eventWriter;
};

// The RegisterModule method is the 
// main entry point for the DLL.
// dwServerVersion: the current server version.
// pModuleInfo: the current 
// IHttpModuleRegistrationInfo pointer.
// pGlobalInfo: the current IHttpServer pointer.
// return: the value returned by calling the
// CGlobalCacheModule::RegisterGlobalModule
// method.
HRESULT
__stdcall
RegisterModule(
    DWORD dwServerVersion,
    IHttpModuleRegistrationInfo* pModuleInfo,
    IHttpServer* pGlobalInfo
)
{        
    // Call the static method for initialization.
    return CGlobalCacheModule::RegisterGlobalModule            
        (dwServerVersion, 
         pModuleInfo, 
         pGlobalInfo);             
}

Pour plus d’informations sur la création et le déploiement d’un module DLL natif, consultez Procédure pas à pas : création d’un module HTTP Request-Level à l’aide de code natif.

Le code ci-dessus écrit un nouvel événement dans le journal des applications du observateur d'événements, où la zone Données contient une chaîne similaire à la suivante.

IHttpCacheSpecificData::GetFlushed: false  

Vous pouvez éventuellement compiler le code à l’aide de la convention d’appel __stdcall (/Gz) au lieu de déclarer explicitement la convention d’appel pour chaque fonction.

Spécifications

Type	Description
Client	- IIS 7.0 sur Windows Vista - IIS 7.5 sur Windows 7 - IIS 8.0 sur Windows 8 - IIS 10.0 sur Windows 10
Serveur	- IIS 7.0 sur Windows Server 2008 - IIS 7.5 sur Windows Server 2008 R2 - IIS 8.0 sur Windows Server 2012 - IIS 8.5 sur Windows Server 2012 R2 - IIS 10.0 sur Windows Server 2016
Produit	- IIS 7.0, IIS 7.5, IIS 8.0, IIS 8.5, IIS 10.0 - IIS Express 7.5, IIS Express 8.0, IIS Express 10.0
En-tête	Httpserv.h

Voir aussi

IHttpCacheSpecificData, interface