Currently the name used internally is modified and holds the shortened
name of the nodes/instances. This has caused issues before, since we
always have to strip the suffix from input data and reapply it if we
need to send data back to Ganeti.

This patch changes the code such that the names are never modified, only
the alias, and all the internal computations can forget about the common
suffix addition/removal.

GHC 6.12 has become more picky about unused imports, so we need to
remove/tighten some of them.

This patch adds the new request loading/execution (trivial), but the
actual response formatting becomes more difficult as now the response
type differs by request.

Signed-off-by: Iustin Pop <iustin@google.com>

In preparation for multiple responses, we change from Maybe to List
(both used in the container sense).

This allows us to keep the same workflow for all kind of requests.

Signed-off-by: Iustin Pop <iustin@google.com>

This prints the initial node list on stderr, since stdout is reserved for the
iallocator protocol (even though ganeti won't pass -p itself).

The Makefile was intented to be -Wall and not simply -W, but I missed
that. This enables more warnings and also enables -Werror (except for
the tests).

This patch moves all the command line options and their internal
representation into CLI.hs. This means that duplicated options between
any two binaries are no longer declared twice, and that we no longer
need the two *Option classes.

Currently, the tryAlloc and tryReloc function return a list with all the
results, both failures and successes. This is fine for hail, which does
one round of allocations, but is not so good for hspace, which does
iterative rounds; since at each (successful) step we only take the best
solution, it means that we're using lots of heap space to compute and
store node lists which are thrown away at the end of the step.

This patch changes these two functions and their callers in hail/hspace
to only return the best solution, and error/success counters. This
allows hspace to run in a much smaller space, and reduces GC cost
greatly.

Overall, it is a cleanup, as hail/hspace did a lot of work to chose this
best solution, whereas now it's automatically promoted within
Cluster.concatAllocs.

Currently the Cluster.AllocSolution type is defined as a list of
‘(OpResult Node.list, …)’ and the results for applyMove are defined as
‘(OpResult Node.List, …)’. Both these means that the failure/success
indication is hidden in the first elements of this tuple, which makes is
harder to add other elements depending on the success/failure (like the
score for the new node list).

This patch moves the OpResult to outside of the tuple, in effect making
all these ‘OpResult (…)’ which makes the internal tuple elements
consistent. The patch is affecting the applyMove, tryAlloc and
tryRealloc functions, and only briefly the hail and hspace programs.

Currently many of the exit and warning conditions mistakenly display error
messages on stdout, which makes parsing the output of programs harder. This
patch attempts to fix such occurrences.

This big patch cleans up the code per hlint indications. Many removals
of extra parentheses, replacements of concat . map with concabtMap,
extra dollar signs, eta reductions, etc. were performed.

The code still compiles and passes a couple of manual tests on sample
files. The individual changes are also small enough as to be visually
easy to confirm.

Currently the allocation/move operations workflow return ‘Maybe a’,
which is very convenient but loses all details about the failure mode.

This patch introduces a new data type which encodes the specific failure
mode. It is not yet used correctly (e.g. all node operations result in
FailN1), but the workflow is updated. Most of the changes are in the
hail/hspace tools, the library code required only trivial adjustments.

This removes some unused functions and imports to cleanup the warnings.

In a few places (e.g. tryRead or any printf call) it's a little bit hard
to add the correct type signatures, but in the it is possible to fix
these warnings (which can bite one in subtle cases).

Currently tryAlloc/tryReloc do not return the new instance, as this is
not needed for IAllocator alloc/reloc requests. However, for computing
the space, the new instance is useful, so we modify these functions to
return this information too.

The patch also improves hspace to have (with default parameters) a
parseable output.

This doc-patch adds copyright and license information to (hopefully) all
needed files.

These are generic enough to be used from multiple places, they belong
better in Cluster.hs than in the hail source.

These two will be more generic than now, and belong somewhere else -
Loader.hs is a generic module for data loading, thus we move them there.

This is a first step towards full datatype renaming. That requires more
changes, so at first we only want to document clearly what is a node
index, what is an instance index, and what is a plain Int.

This patch makes the Types module a base module, and Node/Instance ones
import it, from the previous (opposite) situation. This will allow in
the future to use newtypes for the index and name types.

This patch fixes the relocate-to-primary-node problem, and doesn't mark
the excluded nodes as offline anymore (we don't use them anyway, so
let's not use a different/fake cluster state).

This patch implements filtering out of the offline/drained nodes and
fixes a bug in IAllocator.hs parsing (similar to an older bug in Rapi.hs
from where the code was copied).

This patch implements non-mirrored instance allocation, by allocating as
secondary node “noSecondary”.

Both allocate and relocate compute new node lists, whose score must be
ranked and the best option chosen. This means we can convert the code to
a generic function.

This patch implements allocate for two node requests. One node requests
can be done as soon as we have a valid allocateOn function for single
nodes.

This patch completes the implementation of hail relocate. It maps all
valid destination nodes through a ReplaceSecondary IMove, filters out
the failed relocations, computes the resulting scores and picks the
lowest one.

This patch implements a very stupid (and broken) version of hail
‘allocate’.

This is not yet used.

Since we have Node/Instance.name, we can now simplify a few constructs.

This patch generalizes a little the CLI handling by not passing in a
special function for help and such, but instead requiring that the
options object supports some common functionality.

This new big patch does a couple of more cleanups in the loading of data
chapter:
  - introduce a Types module that holds most types (except the base
    Node/Instance/etc.) so that multiple other modules can use these
    (instead of only Cluster and its users)
  - bring IAlloc.hs in line with the recent changes of providing data
    types and not strings
  - removal of obsolete Utils.hs json-related functions

This makes hail compile and get a request parsed via IAlloc, but nothing
more.

This patch changes Cluster.loadData to return a Result, instead of
directly the values; this will allow us to return meaningful error
values (e.g. when an instances lives on unknown node) rather than simply
abort. Currently the result is always an Ok, the actual signalling of
errors will come later.

Its callers are changed to accommodate for the new return type and to
display errors as needed.

This big patch converts from our home-grown monad-like constructs
(the Either stuff) to a real, Either-like-but-another-name monad.

We introduce a “Result a” monad, and this allows dropping many of the
extra constructs. Hopefully the code is also more clear.

Many of the functions could now be written in a generic-monad style,
instead of Result specifically, but that will come in future patches.

IAlloc.hs also has some unrelated patches.

This option is the opposite of the --verbose option, and it allows
decreasing the verbosity level from the default of one to zero (which
currently doesn't show the warning messages for missing disk/memory).

This patch moves the oneline format into a separate function for easier
usage.

For clusters with no instances, there is no point in computing either
the score or in running the algorithm. In this case, we exit prematurely
and when running in one-line mode we show dummy information.

This new parameter causes the algorithm to finish (or even not start at
all) if we reach/have a score better than it.