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  1. Subversion
  2. SVN-981

tree copies can be O(N) when copyfrom args not used

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    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Duplicate
    • Affects Version/s: all
    • Fix Version/s: unscheduled
    • Component/s: libsvn_repos
    • Labels:

      Description

      Mike's email says it all:
      
      From: cmpilato@collab.net
      Subject: Re: cheap copies
      To: Ben Collins-Sussman <sussman@collab.net>
      Cc: SVN Dev List <dev@subversion.tigris.org>
      Date: 08 Nov 2002 18:04:55 -0600                                     
                
      
      Ben Collins-Sussman <sussman@collab.net> writes:
      
      > Whenever we make a branch or tag (svn cp URL URL), it seems to take a
      > disconcertingly long time for the commit to finish.  I mean, it takes
      > *noticeably* longer than when I simply commit a few file
      > changes... like 10 seconds instead of 2 or 3.
      >
      > Something seems to be interfering with our magic O(1) copies.
      >
      > Maybe it's something within libsvn_fs, like walking the tree to make
      > every node immutable?
      
      Every node?  It walks the FROM_PATH read-only, then walks the TO_PATH
      making things mutable (between '/' and TO_PATH's parent).
      
      > Maybe the post-commit-hook script is doing a full tree walk to
      > discover it's a copy?
      
      Uh...no.  We background our post-commit hook.
      
      > There's an O(N) thing happening somewhere, and I'm about a hair away
      > from filing an issue.
      
      Are you sure it's O(N)?  Have you copied anything other than /trunk to
      verify this?
      
      A-ha.  I found the culprit (4 minutes to debug...it's *goooooood* to
      know the filesystem code).
      
      mod_dav_svn's MERGE response handle doesn't use the USE_COPYFROM_ARGS
      flag to svn_repos_dir_delta().  Which means that dir_delta is sending
      an ADD for every single file and dir in the copied tree (despite the
      fact that client doesn't give a rip, and will immediately discard this
      info as rubbish on a repos-to-repos copy operation).
      
      All we need now is a fix.
      

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              • Assignee:
                Unassigned
                Reporter:
                kfogel Karl Fogel
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                  Updated:
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