[PATCH] remote-hg: Fix cloning and sharing bug

[Antoine Pelisse <apelisse@gmail.com>]

6796d49 (remote-hg: use a shared repository store) introduced sharing
repository capability, but it broke backward-compatibility with already
existing repositories.

Indeed, 6796d49 assumes that .git/hg/.hg (the shared repository) will
exist if .git/hg exists.
This can be false for already existing clones. It can also be false for
local repository that are not cloned.

Fixes the compatibility break by always cloning into .git/hg/.shared
(even for local repositories). In order to avoid expensive clone
retrieval from slow remotes, also look for already existing clones in
.git/hg/$aliases/clone.

Reported-by: Joern Hees <dev@joernhees.de>
Suggested-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
---
Hey,

OK, I think this version will work in all cases.
Either you clone local and then remote, or remote and then local,
or old version local and then remote, or old version remote and then local:
You will always either have .shared repo already cloned, or will find a way to
create it: either by using an already existing clone, or by cloning the given
url (and that last step can't be done if we don't use .shared).

I also decided to always clone local repositories because what Jörn Hees
said makes sense:
If you have a local clone of a big repository, and then want to add a slow
remote, you would have to reclone everything.
I think the trade-off is good, because clone from local should not be that
time expensive (maybe it can be on disk-space though).

As I changed indentation, the patch may deserve a second look with -w.

Cheers,
Antoine

 contrib/remote-helpers/git-remote-hg |   47 ++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/contrib/remote-helpers/git-remote-hg b/contrib/remote-helpers/git-remote-hg
index 0194c67..487c13d 100755
--- a/contrib/remote-helpers/git-remote-hg
+++ b/contrib/remote-helpers/git-remote-hg
@@ -385,33 +385,42 @@ def get_repo(url, alias):

     extensions.loadall(myui)

-    if hg.islocal(url) and not os.environ.get('GIT_REMOTE_HG_TEST_REMOTE'):
-        repo = hg.repository(myui, url)
-        if not os.path.exists(dirname):
-            os.makedirs(dirname)
-    else:
-        shared_path = os.path.join(gitdir, 'hg')
-        if not os.path.exists(shared_path):
+    hgdir = os.path.join(gitdir, 'hg')
+    try:
+        os.mkdir(hgdir)
+    except OSError:
+        pass
+
+    shared_path = os.path.join(hgdir, '.shared')
+    if not os.path.exists(shared_path):
+        for remote in os.listdir(hgdir):
+            try:
+                hg.clone(myui, {}, os.path.join(hgdir, remote, 'clone'),
+                         shared_path, update=False, pull=True)
+                break
+            except error.RepoError:
+                pass
+        else:
             try:
                 hg.clone(myui, {}, url, shared_path, update=False, pull=True)
             except:
                 die('Repository error')

-        if not os.path.exists(dirname):
-            os.makedirs(dirname)
+    if not os.path.exists(dirname):
+        os.makedirs(dirname)

-        local_path = os.path.join(dirname, 'clone')
-        if not os.path.exists(local_path):
-            hg.share(myui, shared_path, local_path, update=False)
+    local_path = os.path.join(dirname, 'clone')
+    if not os.path.exists(local_path):
+        hg.share(myui, shared_path, local_path, update=False)

-        repo = hg.repository(myui, local_path)
-        try:
-            peer = hg.peer(myui, {}, url)
-        except:
-            die('Repository error')
-        repo.pull(peer, heads=None, force=True)
+    repo = hg.repository(myui, local_path)
+    try:
+        peer = hg.peer(myui, {}, url)
+    except:
+        die('Repository error')
+    repo.pull(peer, heads=None, force=True)

-        updatebookmarks(repo, peer)
+    updatebookmarks(repo, peer)

     return repo

--
1.7.9.5