Lockset's remove() function used to return a list of locks we failed to remove.
Rather than doing this we'll return a list of removed locks, so it's more
similar to how acquire() behaves. This patch also fixes the relevant unit tests.

Reviewed-by: imsnah

In a LockSet acquire() returned True on success. This code changes that to
return a set containing the names of the elements acquired. This is still a
true value if we acquired any lock but is slightly more useful (because if
needed one has access to this data without querying for it). The only change
happens if acquiring no locks, which though is a usage which should not
normally happen because it has no practical use.

The patch also changes a some tests to check that the new format is respected.

Reviewed-by: imsnah

This patch changes nothing to the functionality of a LockSet. Rather than
trying to do the whole for loop we try each of its steps. This opens the way to
handle differently a single failure.

Reviewed-by: imsnah

Includes some locking-related constants and explanations on how the
LockManager should be used, the class itself and its test cases.

The class includes:
  - a basic constructor
  - functions to acquire and release lists of locks at the same level
  - functions to add and remove list of locks at modifiable levels
  - dynamic checks against out-of-order acquisitions and other illegal ops

Its testing library checks that the LockManager behaves correctly and that the
external assumptions it relies on are respected.

Reviewed-by: imsnah

Currently the cluster destroy doesn't remove the master role, which
means that the IP address of the cluster remains assigned to the master
node.

This patch fixes this and also a docstring in backend.StopMaster().

Reviewed-by: imsnah

Reviewed-by: imsnah

This one-liner fixes the cluster rename operation. As a side note, we
should have a QA test for this too.

Reviewed-by: imsnah

This patch makes acquire() first look up all the locks in the dict and then try
to acquire them later. The advantage is that if a lockname is already wrong
since the beginning we won't need to first queue and acquire other locks to
find this out.

Of course since there is no locking between the two steps a delete() could
still happen in between, but SharedLocks are safe in this regard and will just
make the .acquire() operation fail if this unfortunate condition happens.

Since the right way to check if an instance/node exists and make sure it won't
stop existing after that is acquiring its lock this improves the common case
(checking for an incorrect name) while not penalizing correctness, or
performance as would happen if we kept a lock for the whole process.

Reviewed-by: iustinp

A LockSet represents locking for a set of resources of the same type. A thread
can acquire multiple resources at the same time, and release some or all of
them, but cannot acquire more resources incrementally at different times
without releasing all of them in between.

Internally a LockSet uses a SharedLock for each resource to be able to grant
both exclusive and shared acquisition. It also supports safe addition and
removal of resources at runtime. Acquisitions are ordered alphabetically in
order to grant them to be deadlock-free. A lot of assumptions about how the
code interacts are made in order to grant both safety and speed; in order to
document all of them the code features pretty lenghty comments.

The test suit tries to catch most common interactions but cannot really tests
tight race conditions, for which we still need to rely on human checking.

This is the second basic building block for the Ganeti Lock Manager. Instance
and Node locks will be put in LockSets to manage their acquisition and release.

Reviewed-by: imsnah

Some options were missing in the gnt-cluster init man page.  This patch adds
them, removes an empty line, and clarifies a bit more some requirements.

Reviewed-by: schreiberal

Even if the target instance is down or we are not checking for IP conflicts
changing an instance name to a new one which is already in the cluster is
doomed to fail, because in a lot of places (among which figures the mind of
most users/admins) instance names are assumed to be unique.

Reviewed-by: imsnah

Reviewed-by: imsnah

Reviewed-by: iustinp

Reviewed-by: ultrotter

Reviewed-by: iustinp

Reviewed-by: iustin

Change comments to printed information, some cleanup. These changes
are from November 2007. The test is not perfect yet.

Reviewed-by: iustinp

This patch replaces some hardcoded strings with their corresponding constant in `_GenerateDiskTemplate()`.

Reviewed-by: iustinp

The cron file in ganeti's example directory is now static, and executes
ganeti-watcher in /usr/local/sbin no matter where it's really installed. With
this patch we generate it at build time substituting the right value of
@SBINDIR@ from ganeti.cron.in. We also make sure ganeti-watcher exists and is
executable before running it.

This is targeted at 1.2 as well.

Reviewed-by: iustinp

This patch switches from the twisted usage for inter-node protocol to
simple BaseHTTPServer/httplib. The patch has more deletions because we
use no authentication, no encryption at all.

As such, this is just for trunk, and only for testing. What it brings is
the ability to use the rpc library from within multiple threads in
parallel (or it should so).

Since the changes are very few and non-intrusive, they can be reverted
without impacting the rest of the code.

This passes burnin. QA was not tested.

Reviewed-by: imsnah

- Check that even a shared acquire() fails on a deleted lock
- Check that delete() fails on a lock you share (must own it or nothing)

These are assumptions I build on in future code, so better check for them.
Currently no code change is necessary for them to be valid.

Reviewed-by: iustinp

The _doItDelete helper code was supposed to be used to dispatch threads that
deleted the SharedLock. It actually just acquired it exclusively. This remained
unnoticed as the helper thread is just used to test interaction, not the delete
code by itself, and delete requires an exclusive acquire anyway.

Reviewed-by: imsnah

gnt-instance replace-disks used to be called replace_disks.

Reviewed-by: iustinp

This new operation lets a lock be cleanly deleted. The lock will be exclusively
held before deletion, and after it pending and future acquires will raise an
exception. Other SharedLock operations are modify to deal with delete() and to
avoid code duplication.

This patch also adds unit testing for the new function and its interaction with
the other lock features. The helper threads are sligtly modified to handle and
report the condition of a deleted lock. As a bonus a non-related unit test
about not supporting non-blocking mode yet has been added as well.

This feature will be used by the LockSet in order to support deadlock-free
delete of resources. This in turn will be useful to gracefully handle the
removal of instances and nodes from the cluster dealing with the fact that
other operations may be pending on them.

Reviewed-by: iustinp

Use the actual class name rather than a spaced version of it.

Reviewed-by: iustinp

Note: we don't update for now the install.sgml file with the new version
number, as there are no other changes. We'll update the web site to
indicate that the current install.html document is valid for 1.2.3 too.

Reviewed-by: imsnah,ultrotter

This reverts commit 604 as the upgrade tool should not be in the 1.3 branch.

Reviewed-by: schreiberal

Reviewed-by: imsnah

This patch adds the DRBD upgrade tool in the archive and in the
installed tools dir, and its associated README in the doc_DATA target.

Reviewed-by: ultrotter

Due to an indentation error only the last instance queried got returned by
LUQueryInstanceData. Moving the append() call inside the for cycle to fix this
issue.

This is a one-liner targeted at 1.2.3

Reviewed-by: iustinp

Reviewed-by: iustinp

QA suite which tests gnt-instance modify has uncovered another issue related to
mac export.

Reviewed-by: imsnah

This tiny patch fixes the breakage that the previous patch about
activation did by removing the Close() call after activation.

The initial reason for that call was that if the device is already
active and open, but we need it closed, we close it automatically.

This however conflicts with the 2-step open in the case the instance is
already open.

It makes sense to remove the call since in the current Ganeti setup,
just doing Close() is not enough to change the device from (e.g.)
primary to secondary, as some devices (e.g. md) might need Shutdown not
Close.

It also gets rid of a Close() in the CreateBlockDevice function, due to
the same reasoning (although in Create the child should not have a
different status anyway).

Reviewed-by: imsnah

This tiny patch fixes the verbose option to actually work, and also when
creating instances it logs the secondary node too (even if this doesn't
apply for plain templates, it doesn't create an error).

Reviewed-by: imsnah

This patch adds a new field available for selection in gnt-instance list
names "status" which represents the combined value of "admin_state" and
"oper_state". Since this is much easier to parse (e.g. gnt-instance list
|grep ERROR), we also modify the default field list to use this instead
of the admin/oper state fields.

Reviewed-by: imsnah

Reviewed-by: iustinp

DRBD 8.2 uses a double integer field ad protocol version, rather than a single
one. This patch fixes the ganeti parsing code, allowing both the old and the
new version type. In order to do so the internal _GetVersion function is
changed to return a dict, rather than a list, and the second protocol field is
added, only if present, as proto2.

This is a fix for issue 24.

Reviewed-by: iustinp

Reviewed-by: ultrotter