branchcache: skip entries that are topological heads in the on disk file
In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.
So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.
#require unix-permissions no-root no-windows no-rhg
XXX-RHG this test hangs if `hg` is really `rhg`. This was hidden by the use of
`alias hg=rhg` by run-tests.py. With such alias removed, this test is revealed
buggy. This need to be resolved sooner than later.
repository itself is non-readable
---------------------------------
$ hg init no-read
$ hg id ssh://user@dummy/no-read
000000000000
$ chmod a-rx no-read
$ hg id ssh://user@dummy/no-read
remote: abort: $EACCES$: *$TESTTMP/no-read/.hg* (glob)
abort: no suitable response from remote hg
[255]
special case files are visible, but unreadable
----------------------------------------------
This is "similar" to the test above, but the directory is "traversable". This
seems an unexpected case in real life, but we test it anyway.
$ hg init other
$ hg id ssh://user@dummy/other
000000000000
$ for item in `find other | sort -r` ; do
> chmod a-r $item
> done
$ hg id ssh://user@dummy/other
remote: abort: $EACCES$: '$TESTTMP/other/.hg/requires'
abort: no suitable response from remote hg
[255]
directory toward the repository is read only
--------------------------------------------
$ mkdir deep
$ hg init deep/nested
$ hg id ssh://user@dummy/deep/nested
000000000000
$ chmod a-rx deep
$ hg id ssh://user@dummy/deep/nested
remote: abort: $EACCES$: *$TESTTMP/deep/nested/.hg* (glob)
abort: no suitable response from remote hg
[255]
repository has wrong requirement
--------------------------------
$ hg init repo-future
$ hg id ssh://user@dummy/repo-future
000000000000
$ echo flying-car >> repo-future/.hg/requires
$ hg id ssh://user@dummy/repo-future
remote: abort: repository requires features unknown to this Mercurial: flying-car
remote: (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
abort: no suitable response from remote hg
[255]