Handling itemupdated calling itemupdating

Question

I have a custom list (not document library) that i have attached 2 event receivers to. These are itemupdating and itemupdated. My itemupdating event receiver sets a value in a field and my itemupdated sets some permissions on the item. I've noticed that the after the itemupdated method is called the itemupdating method is called again. I presume this is because the i've called properties.ListItem.Update(); I do not want the itemupdating event code to run twice. How can i handle this scenerio?

public override void ItemUpdating(SPItemEventProperties properties)
        {
            base.ItemUpdating(properties);
            if (properties.ListTitle != C.EquipmentList) return;

            //Expiry date calculated field is not available in this event so
            //im recreating the formula to pass to the checkexpirydate method
            DateTime ExpiryDate = CalculateExpiryDate(
                properties.AfterProperties[C.InternalLastCalDate].ToString(),
                properties.AfterProperties[C.InternalNumberOfDaysTillNextCalibration].ToString()
                );

            properties.AfterProperties[C.Status] = CheckExpiryDate(ExpiryDate);
        }

        public override void ItemUpdated(SPItemEventProperties properties)
        {
            try
            {
                base.ItemUpdated(properties);
                if (properties.ListTitle != C.EquipmentList) return;

                properties.Web.AllowUnsafeUpdates = true;
                properties.Web.Site.AllowUnsafeUpdates = true;

                RemoveItemPermission(properties);
                SetCustodianPermissions(properties);

                SPGroup AdminSGroup = properties.Web.SiteGroups[C.AdminsGroup];
                GrantPermission(properties.ListItem, properties.Web, SPRoleType.Administrator, AdminSGroup);

                EventFiringEnabled = false;
                properties.ListItem.SystemUpdate();

            }
            finally
            {
                EventFiringEnabled = true;
                properties.Web.AllowUnsafeUpdates = false;
                properties.Web.Site.AllowUnsafeUpdates = false;
            }
        }

Answer 1

The issue is that these are in two different event receivers. EventFiringEnabled is a thread specific property. The reason it's done this way is that this could cause code from 3rd parties or other developers to function unexpectedly. If you put those into a single event receiver, I would expect that it would work the way you want it to.

I'm looking for an MSDN reference for this.

Edit:
I cannot seem to find anything about this specifically in any MS documentation. But here is the article where I read about this when I was experiencing the same issue. Notice that the article was from the 2007 days.

Disable event firing in SharePoint when updating a list item outside of an event handler

Upon disassembling Microsoft.Sharepoint.dll, I discovered that the above mentioned method actually sets a static, thread-specific, property of SPEventManager class called EventFiringDisabled