67 lines
2.6 KiB
C++
67 lines
2.6 KiB
C++
// Copyright Epic Games, Inc. All Rights Reserved.
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#pragma once
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#include "IVirtualizationBackend.h"
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namespace UE::Virtualization
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{
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/**
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* A basic backend based on the file system. This can be used to access/store virtualization
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* data either on a local disk or a network share. It is intended to be used as a caching system
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* to speed up operations (running a local cache or a shared cache for a site) rather than as the
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* proper backend solution.
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*
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* Ini file setup:
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* 'Name'=(Type=FileSystem, Path="XXX", RetryCount=X, RetryWaitTime=X)
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*
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* Required Values:
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* 'Name': The backend name in the hierarchy.
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* 'Type': The backend will be of type 'FFileSystemBackend'.
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* 'Path': The root directory where the files are stored.
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*
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* Optional Values:
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* RetryCount: How many times we should try to open a payload file for read before giving up with
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* an error. Useful when many threads/processes can be pushing/pulling from the same
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* path/ [Default=10]
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* RetryWaitTime: The length of time the process should wait between each read attempt in milliseconds.
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* Remember that the max length of time that the process can stall attempting to read
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* a payload file is RetryCount * RetryWaitTime; [Default=100ms]
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* EnvPathOverride: The name of the environment variable that the user can set to override 'Path'. This
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* should only ever be set if you wish for the users to be able to choose where the
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* payloads are being stored and do not rely on 'Path' always being used. [Default=""]
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*/
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class FFileSystemBackend final : public IVirtualizationBackend
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{
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public:
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explicit FFileSystemBackend(FStringView ProjectName, FStringView ConfigName, FStringView DebugName);
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virtual ~FFileSystemBackend() = default;
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private:
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/* IVirtualizationBackend implementation */
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virtual bool Initialize(const FString& ConfigEntry) override;
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virtual EConnectionStatus OnConnect() override;
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virtual bool PushData(TArrayView<FPushRequest> Requests, EPushFlags Flags) override;
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virtual bool PullData(TArrayView<FPullRequest> Requests, EPullFlags Flags, FText& OutErrors) override;
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virtual bool DoesPayloadExist(const FIoHash& Id) override;
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private:
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void CreateFilePath(const FIoHash& PayloadId, FStringBuilderBase& OutPath);
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TUniquePtr<FArchive> OpenFileForReading(const TCHAR* FilePath);
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/** The root directory where the payload files should be located. */
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FString RootDirectory;
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/** The number of times to retry opening a payload file for read */
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int32 RetryCount = 10;
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/** The length of time (in milliseconds) to wait after each attempt before retrying. */
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int32 RetryWaitTimeMS = 100;
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};
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} // namespace UE::Virtualization
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