SharePoint ItemAdded and SPFile.OpenBinary(), zero bytes - sharepoint

Question

I have an event receiver tied to a SharePoint 2010 picture library. When a picture is uploaded, I want to open it for processing. Files uploaded with the web interface work fine, but files copied via Windows Explorer view return zero bytes. Simplified code below.
public override void ItemAdded(SPItemEventProperties properties)
{
SPListItem item = properties.ListItem;
SPFile file = item.File;
byte[] buffer = file.OpenBinary(); //buffer has zero bytes for files copied in Windows Explorer!
}
If I insert a delay before opening, it works.
public override void ItemAdded(SPItemEventProperties properties)
{
SPListItem item = properties.ListItem;
SPFile file = item.File;
System.Threading.Thread.Sleep(2000);
byte[] buffer = file.OpenBinary(); //buffer now populated correctly
}
But I though that ItemAdded was only called after everything was done, including file upload.
I also found that file.CanOpenFile(true) always returns true, whether or not OpenBinary works.
How can I make sure the file is ready to open before I call OpenBinary()?
I don't like the Thread.Sleep solution, because I'm sure larger files or a busier server would require more wait. The time required can't be predicted, and I don't want to loop and try again forever.
Update: I originally thought the failure to open was caused by larger files. Question has been updated to reflect the explorer view as the cause. I also find that Windows Explorer copy also triggers ItemUpdated (twice), and I am able to open the file here. A little messy to have 3 triggers, 2 calls to do 1 thing, so I am still open to suggestions.

Answer 1

I just encountered this issue today on SharePoint 2013. I've taken the suggestions listed here and improved upon them.
It's fine making the thread sleep for 2 seconds, but what happens when you have a large file? You're going to run into the same issue.
My code fix is as follows:
//Check if the SPContext is null since Explorer View isn't within the context
if (SPContext.Current == null)
{
//If the initial file length is 0, pause the thread for 2 seconds
if (properties.ListItem.File.Length == 0)
{
System.Threading.Thread.Sleep(2000);
//Since our item exists, run the GetItemById to instantiate a new and updated SPListItem object
var spFile = properties.List.GetItemById(properties.ListItemId);
//SharePoint places an Exclusive lock on the file while the data is being loaded into the file
while (spFile.File.LockType != SPFile.SPLockType.None)
{
System.Threading.Thread.Sleep(2000);
spFile = properties.List.GetItemById(properties.ListItemId);
//We need to check if the file exists, otherwise it will loop forever if someone decides to cancel the upload
if (!spFile.File.Exists)
return;
}
//If someone thought it was a good idea to actually load a 0 byte file, don't do anything else
if (spFile.File.Length == 0)
return;
}
}

Answer 2

I face the same Problem within SP2010 and SP2013. Any Idea how to solve this?
Somehow this have something to do with bigger files. Small Files work without any problems, bigger files (400kb) won't work always.
I have only one hint. If you copy & paste a file over windows explorer (WebDAV) to the Library the EventHandle (ItemAdded) will trigger as soon the File was created. But this doesn't mean the File is already filled with data. I saw this once, my debugger hit my breakpoint even while windows was still busy with the copyprocess.
Would be great to know when the copyprocess is finished. I thought i could do this by just do "spfile.openBinary()" and if its empty, just wait 2 sec and do it again until it will get something bigger than 0 bytes. But this doesnt work! It only work if you are waiting BEFORE you call openBinary() the first time, all other times of calling openBinary() lead to the same result.