迭代實體的所有權變更事件 - AWS SimSpace Weaver

本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

迭代實體的所有權變更事件

若要取得實體在擁有權區域與訂閱區域之間移動的事件，請比較目前和先前實體擁有權與訂閱事件之間的變更。

您可以閱讀以下內容來處理這些事件：

  • Api::SubscriptionChangeList

  • Api::OwnershipEvents

然後，您可以將變更與先前儲存的資料進行比較。

下列範例顯示如何處理實體擁有權變更事件。此範例假設對於在已訂閱實體與擁有實體 (任一方向) 之間進行轉換的實體，擁有權移除/新增事件會先發生，然後在下一個刻度中接著訂閱移除/新增事件。

範例
Result<void> ProcessOwnershipEvents(Transaction& transaction)
{
    using EntityIdsByAction =
        std::unordered_map<Api::ChangeListAction, 
        std::vector<Api::EntityId>>;
    using EntityIdSetByAction =
        std::unordered_map<Api::ChangeListAction, 
        std::unordered_set<Api::EntityId>>;
   
    static EntityIdsByAction m_entityIdsByPreviousOwnershipAction;
    
    EntityIdSetByAction entityIdSetByAction;
   
    /**
     * Enumerate Api::SubscriptionChangeList items 
     * and store Add and Remove events.
     */ 
    WEAVERRUNTIME_TRY(Api::SubscriptionChangeList subscriptionEvents, 
        Api::AllSubscriptionEvents(transaction));
   
    for (const Api::SubscriptionEvent& event : subscriptionEvents.changes)
    {
        const Api::ChangeListAction action = event.action;
    
        switch (action)
        {
        case Api::ChangeListAction::Add:
        case Api::ChangeListAction::Remove:
    
            {
                entityIdSetByAction[action].insert(
                    event.entity.descriptor->id);
                break;
            }
        case Api::ChangeListAction::None:
        case Api::ChangeListAction::Update:
        case Api::ChangeListAction::Reject:
            {
                break;
            }
        }
    }
    
    EntityIdsByAction entityIdsByAction;
    
    /**
     * Enumerate Api::OwnershipChangeList items 
     * and store Add and Remove events.
     */
    
    WEAVERRUNTIME_TRY(Api::OwnershipChangeList ownershipChangeList, 
        Api::OwnershipChanges(transaction));
   
    for (const Api::OwnershipChange& event : ownershipChangeList.changes)
    {
        const Api::ChangeListAction action = event.action;
    
        switch (action)
        {
        case Api::ChangeListAction::Add:
        case Api::ChangeListAction::Remove:
            {
                entityIdsByAction[action].push_back(
                    event.entity.descriptor->id);
                break;
            }
        case Api::ChangeListAction::None:
        case Api::ChangeListAction::Update:
        case Api::ChangeListAction::Reject:
            {
                break;
            }
        }
    
    }
      
    std::vector<Api::EntityId> fromSubscribedToOwnedEntities;
    std::vector<Api::EntityId> fromOwnedToSubscribedEntities;
   
    /**
     * Enumerate the *previous* Api::OwnershipChangeList Remove items
     * and check if they are now in 
     * the *current* Api::SubscriptionChangeList Add items.
     *
     * If true, then that means 
     * OnEntityOwnershipChanged(bool isOwned = false)
     */ 
    for (const Api::EntityId& id : m_entityIdsByPreviousOwnershipAction[
        Api::ChangeListAction::Remove])
    {
        if (entityIdSetBySubscriptionAction[
            Api::ChangeListAction::Add].find(id) !=
                entityIdSetBySubscriptionAction[
                Api::ChangeListAction::Add].end())
        {
            fromOwnedToSubscribedEntities.push_back(id);
        }
    }
    
   
    /**
     * Enumerate the *previous* Api::OwnershipChangeList Add items
     * and check if they are now in 
     * the *current* Api::SubscriptionChangeList Remove items.
     *
     * If true, then that means 
     * OnEntityOwnershipChanged(bool isOwned = true)
     */ 
    for (const Api::EntityId& id : m_entityIdsByPreviousOwnershipAction[
        Api::ChangeListAction::Add])
    {
        if (entityIdSetBySubscriptionAction[
            Api::ChangeListAction::Remove].find(id) !=
            
                entityIdSetBySubscriptionAction[
                Api::ChangeListAction::Remove].end())
        {
            fromSubscribedToOwnedEntities.push_back(id);
        }
    }
    
    m_entityIdsByPreviousOwnershipAction = entityIdsByOwnershipAction;
    
    return Success();
}