Fuzz tests have shown that git cat-file --batch sometimes stops running.
It's not yet known why (no error message; repo seems ok). But this is
something we can deal with in the CoProcess framework, since all 3 types of
long-running git processes should be restartable if they fail.
Note that, as implemented, only IO errors are caught. So an error thrown
by the reveiver, when it sees something that is not valid output from
git cat-file (etc) will not cause a restart. I don't want it to retry
if git commands change their output or are just outputting garbage.
This does mean that if the command did a partial output and crashed in the
middle, it would still not be restarted.
There is currently no guard against restarting a command repeatedly, if,
for example, it crashes repeatedly on startup.
The current manual mode preferred content expression is:
"present and (((exclude=*/archive/* and exclude=archive/*) or (not (copies=archive:1 or copies=smallarchive:1))) or (not copies=semitrusted+:1))"
The old matcher misparsed this, to basically:
OR (present and (...)) (not copies=semitrusted+:1))
The paren handling and indeed the whole conversion from tokens to the
matcher was just wrong. The new way may not be the cleverest, but I think
it is correct, and you can see how it pattern matches structurally against
the expressions when parsing them.
That expression is now parsed to:
MAnd (MOp <function>)
(MOr (MOr (MAnd (MOp <function>) (MOp <function>)) (MNot (MOr (MOp <function>) (MOp <function>))))
(MNot (MOp <function>)))
Which appears correct, and behaves correct in testing.
Also threw in a simplifier, so the final generated Matcher has less
unnecessary clutter in it. Mostly so that I could more easily read &
confirm them.
Also, added a simple test of the Matcher to the test suite.
There is a small chance of badly formed preferred content expressions
behaving differently than before due to this rewrite.
I hope this will be easier to reason about, and less buggy. It was
certianly easier to write!
An immediate benefit is that with a traversable queue of push requests to
select from, the threads can be a lot fairer about choosing which client to
service next.
As seen in this bug report, the lifted exception handling using the StateT
monad throws away state changes when an action throws an exception.
http://git-annex.branchable.com/bugs/git_annex_fork_bombs_on_gpg_file/
.. Which can result in cached values being redundantly calculated, or other
possibly worse bugs when the annex state gets out of sync with reality.
This switches from a StateT AnnexState to a ReaderT (MVar AnnexState).
All changes to the state go via the MVar. So when an Annex action is
running inside an exception handler, and it makes some changes, they
immediately go into affect in the MVar. If it then throws an exception
(or even crashes its thread!), the state changes are still in effect.
The MonadCatchIO-transformers change is actually only incidental.
I could have kept on using lifted-base for the exception handling.
However, I'd have needed to write a new instance of MonadBaseControl
for the new monad.. and I didn't write the old instance.. I begged Bas
and he kindly sent it to me. Happily, MonadCatchIO-transformers is
able to derive a MonadCatchIO instance for my monad.
This is a deep level change. It passes the test suite! What could it break?
Well.. The most likely breakage would be to code that runs an Annex action
in an exception handler, and *wants* state changes to be thrown away.
Perhaps the state changes leaves the state inconsistent, or wrong. Since
there are relatively few places in git-annex that catch exceptions in the
Annex monad, and the AnnexState is generally just used to cache calculated
data, this is unlikely to be a problem.
Oh yeah, this change also makes Assistant.Types.ThreadedMonad a bit
redundant. It's now entirely possible to run concurrent Annex actions in
different threads, all sharing access to the same state! The ThreadedMonad
just adds some extra work on top of that, with its own MVar, and avoids
such actions possibly stepping on one-another's toes. I have not gotten
rid of it, but might try that later. Being able to run concurrent Annex
actions would simplify parts of the Assistant code.
That's needed in files used to build the configure program.
For the other files, I'm keeping my __WINDOWS__ define, as I find that much easier to type.
I may search and replace it to use the mingw32_HOST_OS thing later.
Run the same code git-annex used to get the sha, including its sanity
checking. Much better than old grep. Should detect FreeBSD systems with
sha commands that output in stange format.
For an unknown reason, getAddrInfo currently is segfaulting. Note that
in February, I had used warpDebug, which uses getAddrInfo, and it worked.
Don't know if my toolchain has changed and broke it, or it's due to having
a different Android device now. Anyway, work around it by hardcoding the
address to use.
This caused the code to fail on Android, which doesn't know that flag.
It seems best to let the OS default flags be used. Tested working ok on
Linux. The only difference on Linux is it might return a v4mapped ipv6
address sometimes.
