[tahoe-lafs-trac-stream] [tahoe-lafs] #2040: mutable files: expose test-and-set operations to HTTP clients

[tahoe-lafs]

#2040: mutable files: expose test-and-set operations to HTTP clients
---------------------+---------------------------
 Reporter:  daira    |          Owner:  daira
     Type:  defect   |         Status:  new
 Priority:  normal   |      Milestone:  undecided
Component:  unknown  |        Version:  1.10.0
 Keywords:           |  Launchpad Bug:
---------------------+---------------------------
 From ticket:413#comment:2
 * Dirnode operations could accept a new argument which provides test-and-
 set semantics, perhaps "if-old-version-is=XYZ". The webapi protocol would
 only apply the requested changes if the "current best version" is also
 described as XYZ
 * The human-oriented "wui" could acquire if-old-version-is= arguments on
 all the buttons it provides. If the directory has been changed between the
 time the directory page was rendered and the time someone clicks a button,
 the operation would be rejected with a note encouraging the user to reload
 the page (and thus get the latest version).

 Both mutable files and directories could have a control like this.

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Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2040>
tahoe-lafs <https://tahoe-lafs.org>
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