By default cmake builds its own curl, without SSL support. This
patch enables SSL when building cmake, fixing the following error:
error: downloading 'https://...' failed
status_code: 1
status_string: "Unsupported protocol"
log: Protocol "https" not supported or disabled in libcurl
This changes the hash algorithm so that it does much less object
allocation and copying, and so that it is correct.
The old version of `_cmp_key()` would call `sorted_deps`, which would
call `flat_dependencies` to get a list of dependencies so that it
could sort them in alphabetical order. This isn't necessary in the
`_cmp_key()`, and in fact we want more DAG structure than that to be
included in the `_cmp_key()`.
The new version constructs a tuple without copying the Spec DAG, and
the tuple contains hashes of sub-DAGs that are computed recursively
in-place. This is way faster than the previous algorithm and reduces
the numebr of copies significantly. It is also a correct DAG hash.
Example timing and copy counts for the different hashing algorithms
we've tried:
Original (wrong) Spec hash:
```
106,170 copies
real 0m5.024s
user 0m4.949s
sys 0m0.104s
```
Spec hash using YAML `dag_hash()`:
```
3,794 copies
real 0m5.024s
user 0m4.949s
sys 0m0.104s
New no-copy, no-YAML hash:
```
3,594 copies
real 0m2.543s
user 0m2.435s
sys 0m0.104s
```
So now we have a hash that is correct AND faster.
The remaining ~3k copies happen mostly during concretization, and as
all packages are initially loaded. I believe this is because Spack
currently has to load all packages to figure out virtual dependency
information; it could also be becasue there ar a lot of lookups of
partial specs in concretize. I can investigate this further.
Flux package reworked to include all new dependencies, fixed issues with a
clean-build of hwloc, lua and czmq as well that prevented flux from building
cold on a minimal system.
- _cross_provider_maps() had suffered some bit rot (map returned was
ill-formed but still worked for cases with one vdep)
- ProviderIndex.satisfies() was only checking whether the result map
was non-empty. It should check whether all common vdeps are *in*
the result map, as that indicates there is *some* way to satisfy
*all* of them. We were checking whether there was some way to
satisfy *any one* of them, which is wrong.
- Above would cause a problem when there is more than one vdep provider.
- Added test that covers this case.
- Added `constrained()` method to Spec. Analogous to `normalized()`:
`constrain():constrained() :: normalize():normalized()`
