The commit thread now has access to a channel containing the times of
all uncommitted changes. This lets it be smart about detecting busy times
when a batch job is running (such as rm -rf, or untarring something, etc),
and avoid committing until it's done. While at the same time, instantly
committing one-off changes that the user is going to expect to see
immediately.
I had to use STM to implement the channel, because of
http://hackage.haskell.org/trac/ghc/ticket/4154
While this adds a dependency, I always wanted to use STM, so this actually
makes me happy. ;)
Also happy that shouldCommit is a pure function, so other commit smartness
strategies can easily be played with. Although the current one seems pretty
good.
There is one bug, for some reason it does double commits, every time.
Fixes build breakage when both 'mtl' and 'monads-tf' are present:
$ make git-annex
> ghc -O2 -Wall -ignore-package monads-fd -outputdir tmp -IUtility -DWITH_S3 --make git-annex Utility/libdiskfree.o
>
> Common.hs:6:8:
> Ambiguous module name `Control.Monad.State.Strict':
> it was found in multiple packages: monads-tf-0.1.0.0 mtl-2.1.1
> make: *** [git-annex] Error 1
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
The Haskell code uses tabs for indentation, and displays well with
tab-width set to 2. So, I created a .dir-locals.el (applies to all
files opened in emacs at or below ./), which sets 'tab-width' to 2,
turns on 'indent-tabs-mode', and highlights leading spaces in
'haskell-mode'.
The creation of the 'git-annex-shell' symlink was in 'postInst' hook.
I combined it with the man-page installation in a 'postInst' hook and
a 'postCopy' hook. I don't understand how to use the `cabal copy`
command, but the examples I looked at defined both hooks.
Relevant comments from the source:
* man-page installation:
See http://www.haskell.org/haskellwiki/Cabal/Developer-FAQ#Installing_manpages.
Based on pandoc's and lhs2tex's 'Setup.installManpages' and
'postInst' hooks.
My understanding: 'postCopy' is run for `cabal copy`, 'postInst' is
run for `cabal inst`, and copy is not a generalized install, so you
have to write two nearly identical hooks.
Summary of hooks:
http://www.haskell.org/cabal/release/cabal-latest/doc/API/Cabal/Distribution-Simple-UserHooks.htm--
Other people are also confused:
* Bug: 'postCopy' and 'postInst' are confusing:
http://hackage.haskell.org/trac/hackage/ticket/718
* A cabal maintainer suggests using 'postCopy' instead of
'postInst', because `cabal install` is `cabal copy` followed by
`cabal register`:
http://www.haskell.org/pipermail/libraries/2008-March/009416.html
Although that sounds desirable, it's not true, as the reply and
experiments indicate.
* the `cabal copy` command:
???: Not sure how you're supposed to use this. E.g., when I do
cabal install --prefix=/tmp/git-annex-install
cabal copy --deistdir=/tmp/git-annex-copy
I get the copy under
/tmp/git-annex-copy/tmp/git-annex-install
Also, `cabal install` fails when given a relative --prefix.
