RE: Recursive externals checkout
>> The problem may be levered by recursively comparing the repository UID
>and
>> the relative path in the uri when the external is resolved. Proofing that
>> this check would be enough is left to the reader. :-)
>
>This will catch the "simple" case when an external includes its own parent
>directory.
>
>But it will not catch mutually recursive externals (svn://path/to/a/
>includes svn://path/to/b/ and vice-versa), there might even exist cycles
>over 3 or more repositories...
That's what I ment with recursive. Since externals resolve from the parent
repository down to the child repository, before checking out the child
repository all parent repositories would have to be checked if it could be a
recursive checkout, i.e. in a python-like pseudocode:
Def Checkout(repoUri, []parents={}):
Foreach childRepoUri in repoUri:
If(IsPossiblyRecursive(childRepoUri, parents)):
Warn()
If(ConfirmByUser())
Checkout(childRepoUri, parents.Append(childRepoUri))
Else
Checkout(childRepoUri, parents.Append(childRepoUri))
Def IsPossiblyRecursive (repoUri, []parents={}):
If(parents.Count > 0)
Foreach parent in parents:
If(IsPossiblyRecursive (repoUri, parent))
True
Else
False
Def IsPossiblyRecursive (repoUri, parent):
If(UID(repoUri) == UID(parent))
# this might be a recursive checkout
# other checks like comparing the relative path could be put here
True
False
Cheers,
Dominik
RE: Recursive externals checkout
>http://tortoisesvn.tigris.org/ds/viewMessage.do?dsForumId=4061&dsMessageId= >2939615 >> >> Do you think svn checkout should be defensive against recursive externals >? > >At elego (where I work) we actually use this as a trick question during >Subversion workshops. People who don't necessarily know about externals >are asked to check out a working copy (which, unknown to them, contains >recursive externals) and are asked to figure out if anything is going >wrong and if so how to fix it. Once they've figured out and fixed the >problem they understand what externals are :) > >That aside, I wouldn't mind if svn printed a warning or error message >when it finds a recursive externals definition. But off-hand I don't >what a good method for detecting recursion would be. >It's somewhat complicated by the fact that externals are currently >separate working copies and that the recursion might be rooted not >only at the immediate parent WC but at some parent of the parent. >Cross-working-copy operations aren't trivial to implement correctly. The problem may be levered by recursively comparing the repository UID and the relative path in the uri when the external is resolved. Proofing that this check would be enough is left to the reader. :-) JMTC
Re: Recursive externals checkout
On Sat, Mar 24, 2012 at 11:34:07AM +, Matthew J Fletcher wrote: > Hi, > > As discussed in this thread,.. > > http://tortoisesvn.tigris.org/ds/viewMessage.do?dsForumId=4061&dsMessageId=2939615 > > Do you think svn checkout should be defensive against recursive externals ? At elego (where I work) we actually use this as a trick question during Subversion workshops. People who don't necessarily know about externals are asked to check out a working copy (which, unknown to them, contains recursive externals) and are asked to figure out if anything is going wrong and if so how to fix it. Once they've figured out and fixed the problem they understand what externals are :) That aside, I wouldn't mind if svn printed a warning or error message when it finds a recursive externals definition. But off-hand I don't what a good method for detecting recursion would be. It's somewhat complicated by the fact that externals are currently separate working copies and that the recursion might be rooted not only at the immediate parent WC but at some parent of the parent. Cross-working-copy operations aren't trivial to implement correctly.
