GenericPlatformBackgroundHttpRequest.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "BackgroundHttpRequestImpl.h"
#include "Containers/UnrealString.h"
#include "HAL/Platform.h"
#include "Interfaces/IBackgroundHttpRequest.h"
#include "Interfaces/IHttpRequest.h"
#include "Templates/SharedPointer.h"
#include "Templates/UniquePtr.h"
 
 
class FGenericPlatformBackgroundHttpRequest 
    : public FBackgroundHttpRequestImpl
{
public:
 
    BACKGROUNDHTTP_API FGenericPlatformBackgroundHttpRequest();
    BACKGROUNDHTTP_API virtual ~FGenericPlatformBackgroundHttpRequest();
 
    //IHttpBackgroundHttpRequest
    BACKGROUNDHTTP_API virtual bool HandleDelayedProcess() override;
    BACKGROUNDHTTP_API virtual void CompleteWithExistingResponseData(FBackgroundHttpResponsePtr BackgroundResponse) override;
    BACKGROUNDHTTP_API virtual void CancelRequest() override;
 
protected:
    //In the default implementation we actually use HTTPRequests instead of HttpBackgroundRequests.
    //This class handles wrapping some of the HttpBackgroundRequest only functionality (such as request lists
    //and notification objects) so they work with non-background HttpRequests
    class FGenericPlatformBackgroundHttpWrapper
    {
    public:
        FGenericPlatformBackgroundHttpWrapper(FBackgroundHttpRequestPtr Request, int MaxRetriesToAttempt);
        ~FGenericPlatformBackgroundHttpWrapper();
 
        void MakeRequest();
        void HttpRequestComplete(FHttpRequestPtr HttpRequestIn, FHttpResponsePtr HttpResponse, bool bSuccess);
 
    private:
        
        bool HasRetriesRemaining() const;
        void UpdateHttpProgress(FHttpRequestPtr UnderlyingHttpRequest, uint64 BytesSent, uint64 BytesReceived);
 
        void CleanUpHttpRequest();
 
        // Gets the current URL the HTTP Request should use by comparing the URLList in the background request to the current retry number.
        // Returns empty FString if we are "out of" retries (CurrentRetryNumber > MaxRetries) or if no valid URL.
        const FString GetURLForCurrentRetryNumber();
 
        //Don't want to provide default implementation. Must provide an IHttpBackgroundRequest to wrap in public constructor
        FGenericPlatformBackgroundHttpWrapper() {}
 
        //Reference to the creating request
        TWeakPtr<class IBackgroundHttpRequest, ESPMode::ThreadSafe> OriginalRequest;
 
        //Current Http Request being processed by this wrapper
        TSharedPtr<IHttpRequest, ESPMode::ThreadSafe> HttpRequest;
 
        //Tracking retry number we are currently on
        int32 CurrentRetryNumber;
 
        //Max number of retries we should do
        int32 MaxRetries;
 
        //How many bytes we had last time we sent progress updates
        uint64 LastProgressUpdateBytes;
    };
 
    TUniquePtr<FGenericPlatformBackgroundHttpWrapper> RequestWrapper;
};