normal form in a single transaction to ensure that if we crash,
either everything is registered or nothing is. This is for
recoverability: unregistered paths in the store can be deleted
arbitrarily, while registered paths can only be deleted by running
the garbage collector.
* Open all database tables (Db objects) at initialisation time, not
every time they are used. This is necessary because tables have to
outlive all transactions that refer to them.
Renamed `fstateRefs' to `fstateRequisites'. The semantics of this
function is that it returns a list of all paths necessary to realise
a given expression. For a derive expression, this is the union of
requisites of the inputs; for a slice expression, it is the path of
each element in the slice. Also included are the paths of the
expressions themselves. Optionally, one can also include the
requisites of successor expressions (to recycle intermediate
results).
* `nix-switch' now distinguishes between an expression and its normal
form. Usually, only the normal form is registered as a root of the
garbage collector. With the `--source-root' flag, it will also
register the original expression as a root.
* `nix-collect-garbage' now has a flag `--keep-successors' which
causes successors not to be included in the list of garbage paths.
* `nix-collect-garbage' now has a flag `--invert' which will print all
paths that should *not* be garbage collected.
up to the given verbosity levels. These currently are:
lvlError = 0,
lvlNormal = 5,
lvlDebug = 10,
lvlDebugMore = 15
although only lvlError and lvlDebug are actually used right now.
substituting for (obvious, really).
* For greater efficiency, nix-pull/unnar will place the output in a
path that is probably the same as what is actually needed, thus
preventing a path copy.
* Even if a output id is given in a Fix package expression, ensure
that the resulting Nix derive expression has a different id. This
is because Nix expressions that are semantically equivalent (i.e.,
build the same result) might be different w.r.t. efficiency or
divergence. It is absolutely vital for the substitute mechanism
that such expressions are not used interchangeably.
value; this potentially dangerous feature enables better
sharing for those paths for which the content is known in
advance (e.g., because a content hash is given).
* Fast builds: if we can expand all output paths of a derive
expression, we don't have to build.
* A function to find all Nix expressions whose output ids are
completely contained in some set. Useful for uploading relevant Nix
expressions to a shared cache.
