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Forum Discussion
shared_link_already_exists just after list_shared_links returned nothing
I maintain an application which uploads files submitted by users and creates a shared link to them.
In most cases it works properly, but today one call to create_shared_link_with_settings returned 409 with the message shared_link_already_exists
It happened few hundred miliseconds after I called list_shared_links and received nothing.
Is there any reasonable explanation to this phenomena?
- Greg-DB
Dropbox Staff
While it's technically possible the race condition occurred in this case (i.e., the link was created by some other client in between your two calls to list_shared_links and create_shared_link_with_settings), that is relatively unlikely given the short time span you indicated.
Is it possible your app called create_shared_link_with_settings twice somehow though? E.g., as an automatic retry in response to a network failure? That could cause this.
In any case though, you should implement error handling in your app for the shared_link_already_exists error, regardless of the timing of a previous call to list_shared_links.I call list_shared_links and create_shared_link_with_settings in the same function, so the first should discover any shared links created earlier, no matter how. That's my idea for this code ;).
In fact I have added this option only as a precaution, because the same function also uploads the file with autorename, so I don't expect any shared link for this file to exist.
Unless this error can be caused by sharing of the parent folder. Of course it would still be a race condition, which is very unprobable .
Is it possible to get shared_link_already_exists on the file just because a parent folder is shared?
- Greg-DB
Even though you call list_shared_links and create_shared_link_with_settings in the same function, there's still a race condition between the two calls, so you should make sure your call to create_shared_link_with_settings can always handle the possibility of a shared_link_already_exists error.
No, having a parent folder shared wouldn't cause a shared_link_already_exists error for a file in that folder.
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