IasHostGroup.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "HAL/CriticalSection.h"
#include "IO/IoStatus.h"
#include "OnDemandBackendStatus.h"
#include "Templates/Function.h"
#include "Templates/SharedPointer.h"
 
namespace UE::IoStore
{
 
class FOnDemandHostGroup;
 
class FIASHostGroup final
{
    struct FImpl;
    using FSharedImpl = TSharedPtr<FImpl, ESPMode::ThreadSafe>;
 
public:
    static TIoStatusOr<FIASHostGroup> Create(FName Name, TConstArrayView<FAnsiString> HostUrls);
    static TIoStatusOr<FIASHostGroup> Create(FName Name, TConstArrayView<FString> HostUrls);
 
    FIASHostGroup();
    FIASHostGroup(FName Name, FAnsiStringView TestPath);
    FIASHostGroup(FName Name, FOnDemandHostGroup&& HostGroup);
    ~FIASHostGroup() = default;
 
    FName GetName() const;
    const FAnsiString& GetTestPath() const;
 
    bool IsResolved() const;
    bool IsConnected() const;
 
    FIoStatus Resolve(TConstArrayView<FAnsiString> HostUrls);
    FIoStatus Resolve(TConstArrayView<FString> HostUrls);
    
    void Connect(int32 HostIndex);
    void Disconnect();
 
    enum class EReconnectionResult : uint8
    {
        AlreadyConnected = 0,
        Reconnected,
        FailedToConnect,
    };
 
    EReconnectionResult AttemptReconnection(uint32 TimeoutMs, std::atomic_bool& CancellationToken);
 
    void OnSuccessfulResponse();
    bool OnFailedResponse();
 
    FAnsiStringView GetPrimaryHostUrl() const;
    int32 GetPrimaryHostIndex() const;
 
    const FOnDemandHostGroup& GetUnderlyingHostGroup() const;
 
    TConstArrayView<FAnsiString> GetHostUrls() const;
private:
    FIASHostGroup(FSharedImpl&& Impl);
 
    void SetPrimaryHost(int32 Index) const;
 
    FSharedImpl Impl;
    
};
 
class FHostGroupManager final
{
    FHostGroupManager() = default;
    ~FHostGroupManager() = default;
 
public:
    DECLARE_TS_MULTICAST_DELEGATE(FOnHostGroupDisconnectedDelegate);
 
    static FHostGroupManager& Get(); 
 
    // TODO: Note that currently we have no way to remove FIASHostGroups
 
    TIoStatusOr<FIASHostGroup> Register(FName Name, FAnsiStringView TestPath); // <- Unresolved
    TIoStatusOr<FIASHostGroup> Register(FName Name, TConstArrayView<FAnsiString> HostUrls); // <- Resolved
 
    FIASHostGroup Find(FName Name);
 
    void ForEachHostGroup(TFunctionRef<void (const FIASHostGroup&)> Callback) const;
 
    void Tick(uint32 TimeoutMs, std::atomic_bool& CancellationToken);
 
    void DisconnectAll(); 
    uint32 GetNumDisconnctedHosts() const;
 
    FOnHostGroupDisconnectedDelegate& OnHostGroupDisconncted()
    {
        return HostGroupDisconnectedDelegate;
    }
 
private:
 
    TArray<FIASHostGroup> HostGroups;
 
    FOnHostGroupDisconnectedDelegate HostGroupDisconnectedDelegate;
 
    mutable FRWLock Mutex;
};
 
} //namespace UE::IoStore