Commit graph

5782 commits

Author SHA1 Message Date
Stephen Sachs
80f5939a94
Install from source if binary cache checksum validation fails (#31696)
* Fix https://github.com/spack/spack/issues/31640

Some packages in the binary cache fail checksum validation. Instead of having to
go back and manually install all failed packages with `--no-cache` option,
requeue those failed packages for installation from source

```shell
$ spack install py-pip
==> Installing py-pip-21.3.1-s2cx4gqrqkdqhashlinqyzkrvuwkl3x7
==> Fetching https://binaries.spack.io/releases/v0.18/build_cache/linux-amzn2-graviton2-gcc-7.3.1-py-pip-21.3.1-s2cx4gqrqkdqhashlinqyzkrvuwkl3x7.spec.json.sig
gpg: Signature made Wed 20 Jul 2022 12:13:43 PM UTC using RSA key ID 3DB0C723
gpg: Good signature from "Spack Project Official Binaries <maintainers@spack.io>"
==> Fetching https://binaries.spack.io/releases/v0.18/build_cache/linux-amzn2-graviton2/gcc-7.3.1/py-pip-21.3.1/linux-amzn2-graviton2-gcc-7.3.1-py-pip-21.3.1-s2cx4gqrqkdqhashlinqyzkrvuwkl3x7.spack
==> Extracting py-pip-21.3.1-s2cx4gqrqkdqhashlinqyzkrvuwkl3x7 from binary cache
==> Error: Failed to install py-pip due to NoChecksumException: Requeue for manual installation.
==> Installing py-pip-21.3.1-s2cx4gqrqkdqhashlinqyzkrvuwkl3x7
==> Using cached archive: /shared/spack/var/spack/cache/_source-cache/archive/de/deaf32dcd9ab821e359cd8330786bcd077604b5c5730c0b096eda46f95c24a2d
==> No patches needed for py-pip
==> py-pip: Executing phase: 'install'
==> py-pip: Successfully installed py-pip-21.3.1-s2cx4gqrqkdqhashlinqyzkrvuwkl3x7
  Fetch: 0.01s.  Build: 2.81s.  Total: 2.82s.
[+] /shared/spack/opt/spack/linux-amzn2-graviton2/gcc-7.3.1/py-pip-21.3.1-s2cx4gqrqkdqhashlinqyzkrvuwkl3x7
```

* Cleanup style

* better wording

Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>

* Update lib/spack/spack/installer.py

Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>

* changes quotes for style checks

* Update lib/spack/spack/installer.py

Co-authored-by: kwryankrattiger <80296582+kwryankrattiger@users.noreply.github.com>

* Addressing @kwryankrattiger comment to use local 'use_cache`

Co-authored-by: Stephen Sachs <stesachs@amazon.com>
Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>
Co-authored-by: kwryankrattiger <80296582+kwryankrattiger@users.noreply.github.com>
2022-11-08 09:19:55 -08:00
Massimiliano Culpo
89976af732
scons: fix Scons builder after multi build-system refactoring (#33753) 2022-11-08 16:03:15 +01:00
Massimiliano Culpo
e4218595de
Rework unit test to avoid tripping into concretization slowdown (#33749) 2022-11-08 10:56:24 +01:00
Greg Becker
c9561c5a0e
intel oneapi classic bootstrapping (#31285)
The `intel` compiler at versions > 20 is provided by the `intel-oneapi-compilers-classic`
package (a thin wrapper around the `intel-oneapi-compilers` package), and the `oneapi`
compiler is provided by the `intel-oneapi-compilers` package. 

Prior to this work, neither of these compilers could be bootstrapped by Spack as part of
an install with `install_missing_compilers: True`.

Changes made to make these two packages bootstrappable:

1. The `intel-oneapi-compilers-classic` package includes a bin directory and symlinks
   to the compiler executables, not just logical pointers in Spack.
2. Spack can look for bootstrapped compilers in directories other than `$prefix/bin`,
   defined on a per-package basis
3. `intel-oneapi-compilers` specifies a non-default search directory for the
   compiler executables.
4. The `spack.compilers` module now can make more advanced associations between
   packages and compilers, not just simple name translations
5. Spack support for lmod hierarchies accounts for differences between package
   names and the associated compiler names for `intel-oneapi-compilers/oneapi`,
   `intel-oneapi-compilers-classic/intel@20:`, `llvm+clang/clang`, and
   `llvm-amdgpu/rocmcc`.

- [x] full end-to-end testing
- [x] add unit tests
2022-11-07 21:50:16 -08:00
Peter Scheibel
1a3415619e
"spack uninstall": don't modify env (#33711)
"spack install foo" no longer adds package "foo" to the environment
(i.e. to the list of root specs) by default: you must specify "--add".
Likewise "spack uninstall foo" no longer removes package "foo" from
the environment: you must specify --remove. Generally this means
that install/uninstall commands will no longer modify the users list
of root specs (which many users found problematic: they had to
deactivate an environment if they wanted to uninstall a spec without
changing their spack.yaml description).

In more detail: if you have environments e1 and e2, and specs [P, Q, R]
such that P depends on R, Q depends on R, [P, R] are in e1, and [Q, R]
are in e2:

* `spack uninstall --dependents --remove r` in e1: removes R from e1
  (but does not uninstall it) and uninstalls (and removes) P
* `spack uninstall -f --dependents r` in e1: will uninstall P, Q, and
   R (i.e. e2 will have dependent specs uninstalled as a side effect)
* `spack uninstall -f --dependents --remove r` in e1: this uninstalls
   P, Q, and R, and removes [P, R] from e1
* `spack uninstall -f --remove r` in e1: uninstalls R (so it is
  "missing" in both environments) and removes R from e1 (note that e1
  would still install R as a dependency of P, but it would no longer
  be listed as a root spec)
* `spack uninstall --dependents r` in e1: will fail because e2 needs R

Individual unit tests were created for each of these scenarios.
2022-11-08 03:24:51 +00:00
Jordan Galby
84a3d32aa3
Fix missing "*.spack*" files in views (#30980)
All files/dirs containing ".spack" anywhere their name were ignored when
generating a spack view.

For example, this happened with the 'r' package.
2022-11-08 02:58:19 +00:00
Harmen Stoppels
3693622edf
reorder packages.yaml: requirements first, then preferences (#33741)
* reorder packages.yaml: requirements first, then preferences
* expand preferences vs reuse vs requirements
2022-11-07 16:16:11 -08:00
Scott Wittenburg
b3b675157c
gitlab ci: Add "script_failure" as a reason for retrying service jobs (#33420)
Somehow a network error when cloning the repo for ci gets
categorized by gitlab as a script failure.  To make sure we retry
jobs that failed for that reason or a similar one, include 
"script_failure" as one of the reasons for retrying service jobs
(which include "no specs to rebuild" jobs, update buildcache
index jobs, and temp storage cleanup jobs.
2022-11-07 16:11:04 -07:00
Tom Scogland
6241cdb27b
encode development requirements in pyproject.toml (#32616)
Add a `project` block to the toml config along with development and CI
dependencies and a minimal `build-system` block, doing basically
nothing, so that spack can be bootstrapped to a full development
environment with:

```shell
$ hatch -e dev shell
```

or for a minimal environment without hatch:

```shell
$ python3 -m venv venv
$ source venv/bin/activate
$ python3 -m pip install --upgrade pip
$ python3 -m pip install -e '.[dev]'
```

This means we can re-use the requirements list throughout the workflow
yaml files and otherwise maintain this list in *one place* rather than
several disparate ones.  We may be stuck with a couple more temporarily
to continue supporting python2.7, but aside from that it's less places
to get out of sync and a couple new bootstrap options.

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>
2022-11-07 15:00:22 -08:00
Scott Wittenburg
28a77c2821
binary_distribution: Speed up buildcache update-index (#32796)
This change uses the aws cli, if available, to retrieve spec files
from the mirror to a local temp directory, then parallelizes the
reading of those files from disk using multiprocessing.ThreadPool.

If the aws cli is not available, then a ThreadPool is used to fetch
and read the spec files from the mirror.

Using aws cli results in ~16 times speed up to recreate the binary
mirror index, while just parallelizing the fetching and reading
results in ~3 speed up.
2022-11-07 21:31:14 +01:00
Harmen Stoppels
cc84ab1e92
Remove known issues (#33738) 2022-11-07 19:41:16 +00:00
Greg Becker
ec05543054
Bugfix: Compiler bootstrapping for compilers that are independently present in env (#32228)
The compiler bootstrapping logic currently does not add a task when the compiler package is already in the install task queue. This causes failures when the compiler package is added without the additional metadata telling the task to update the compilers list.

Solution: requeue compilers for bootstrapping when needed, to update `task.compiler` metadata.
2022-11-07 09:38:51 -08:00
Greg Becker
a30b60f9a6
Apply dev specs for dependencies of roots (#30909)
Currently, develop specs that are not roots and are not explicitly listed dependencies 
of the roots are not applied.

- [x] ensure dev specs are applied.

Co-authored-by: Todd Gamblin <tgamblin@llnl.gov>
2022-11-07 09:37:03 -08:00
Harmen Stoppels
47df88404a
Simplify repeated _add_dependency calls for same package (#33732) 2022-11-07 16:33:18 +01:00
Axel Huebl
1eb35d0378
Doc: lsb-release (#32479)
Without the `lsb-release` tool installed, Spack cannot identify the
Ubuntu/Debian version.
2022-11-07 16:13:17 +01:00
Harmen Stoppels
2ab974f530
concretizer:unify:true as a default (#31787)
`spack env create` enables a view by default (in a weird hidden
directory, but well...). This is asking for trouble with the other
default of `concretizer:unify:false`, since having different flavors of
the same spec in an environment, leads to collision errors when
generating the view.

A change of defaults would improve user experience:

However, `unify:true` makes most sense, since any time the issue is
brought up in Slack, the user changes the concretization config, since
it wasn't the intention to have different flavors of the same spec, and
install times are decreased.

Further we improve the docs and drop the duplicate root spec limitation
2022-11-07 15:38:24 +01:00
Massimiliano Culpo
e045dabb3a
archspec: update version, translate renamed uarchs (#33556)
* Update archspec version

* Add a translation table from old names
2022-11-07 04:50:38 -08:00
Greg Becker
4b84cd8af5
bugfix for matrices with dependencies by hash (#22991)
Dependencies specified by hash are unique in Spack in that the abstract
specs are created with internal structure. In this case, the constraint
generation for spec matrices fails due to flattening the structure.

It turns out that the dep_difference method for Spec.constrain does not
need to operate on transitive deps to ensure correctness. Removing transitive
deps from this method resolves the bug.

- [x] Includes regression test
2022-11-06 16:49:35 -08:00
Greg Becker
fce7bf179f
solver setup: extract virtual dependencies from reusable specs (#32434)
* extract virtual dependencies from reusable specs
* bugfix to avoid establishing new node for virtual
2022-11-06 16:47:07 -08:00
Greg Becker
f3db624b86
package preferences: allow specs to be configured buildable when their virtuals are not (#18269)
* respect spec buildable that overrides virtual buildable
2022-11-06 16:45:38 -08:00
Greg Becker
22c2f3fe89
improve error message for dependency on nonexistant compiler (#32084) 2022-11-06 16:44:11 -08:00
Greg Becker
52cc798948
solver: do not punish explicitly requested compiler mismatches (#30074) 2022-11-06 16:40:00 -08:00
Michael Kuhn
258edf7dac
MesonPackage: disable automatic download and install of dependencies (#33717)
Without this, Meson will use its Wraps to automatically download and
install dependencies. We want to manage dependencies explicitly,
therefore disable this functionality.
2022-11-06 19:34:43 +00:00
Greg Becker
d4b45605c8
allow multiple compatible deps from CLI (#21262)
Currently, Spack can fail for a valid spec if the spec is constructed from overlapping, but not conflicting, concrete specs via the hash.

For example, if abcdef and ghijkl are the hashes of specs that both depend on zlib/mnopqr, then foo ^/abcdef ^/ghijkl will fail to construct a spec, with the error message "Cannot depend on zlib... twice".

This PR changes this behavior to check whether the specs are compatible before failing.

With this PR, foo ^/abcdef ^/ghijkl will concretize.

As a side-effect, so will foo ^zlib ^zlib and other specs that are redundant on their dependencies.
2022-11-06 11:30:37 -08:00
Greg Becker
27e1d28c0b
canonicalize_path: add arch information to substitutions (#29810)
Co-authored-by: becker33 <becker33@users.noreply.github.com>
2022-11-06 10:11:59 +01:00
Massimiliano Culpo
5558940ce6
Add support for Python 3.11 (#33505)
Argparse started raising ArgumentError exceptions
when the same parser is added twice. Therefore, we
perform the addition only if the parser is not there
already

Port match syntax to our unparser
2022-11-05 15:59:12 +01:00
Tom Scogland
3346c0918b
Fix relocation to avoid overwriting merged constant strings (#32253)
Compilers and linker optimize string constants for space by aliasing
them when one is a suffix of another. For gcc / binutils this happens
already at -O1, due to -fmerge-constants. This means that we have
to take care during relocation to always preserve a certain length
of the suffix of those prefixes that are C-strings. 

In this commit we pick length 7 as a safe suffix length, assuming the
suffix is typically the 7 characters from the hash (i.e. random), so
it's unlikely to alias with any string constant used in the sources.

In general we now pad shortened strings from the left with leading
dir seperators, but in the case of C-strings that are much shorter
and don't share a common suffix (due to projections), we do allow
shrinking the C-string, appending a null, and retaining the old part
of the prefix.

Also when rewiring, we ensure that the new hash preserves the last
7 bytes of the old hash.

Co-authored-by: Harmen Stoppels <harmenstoppels@gmail.com>
2022-11-05 11:09:35 +01:00
Peter Scheibel
71d480515b
packages.yaml: set url/git (#33275)
A user may want to set some attributes on a package without actually modifying the package (e.g. if they want to git pull updates to the package without conflicts). This PR adds a per-package configuration section called "set", which is a dictionary of attribute names to desired values. For example:

packages:
  openblas:
    package_attributes:
      submodules: true
      git: "https://github.com/myfork/openblas"

in this case, the package will always retrieve git submodules, and will use an alternate location for the git repo.

While git, url, and submodules are the attributes for which we envision the most usage, this allows any attribute to be overridden, and the acceptable values are any value parseable from yaml.
2022-11-05 08:44:50 +00:00
Massimiliano Culpo
c0ed5612ab
unparser: fix bug in unit test assertion (#33722) 2022-11-05 09:00:54 +01:00
iarspider
9becc82dfc
Fix formatting in packaging guide (#33714) 2022-11-05 02:00:16 +00:00
Greg Becker
912d544afe
demote warning for no source id to debug message (#33657)
* demote warning for no source id to debug message
2022-11-04 21:52:58 +00:00
Greg Becker
53fbaa5dcd
Cray support: use linux platform for newer craype versions (#29392)
Newer versions of the CrayPE for EX systems have standalone compiler executables for CCE and compiler wrappers for Cray MPICH. With those, we can treat the cray systems as part of the linux platform rather than having a separate cray platform.

This PR:
- [x] Changes cray platform detection to ignore EX systems with Craype version 21.10 or later
- [x] Changes the cce compiler to be detectable via paths
- [x] Changes the spack compiler wrapper to understand the executable names for the standalone cce compiler (`craycc`, `crayCC`, `crayftn`).
2022-11-04 14:52:11 -07:00
Greg Becker
a88c74dc17
delegate to cray modules for target args on cray (#17857) 2022-11-04 14:50:05 -07:00
Matthieu Boileau
76ec64859a
Fix typo in docs (#33662) 2022-11-04 20:19:34 +01:00
Massimiliano Culpo
a4f3fe2ac7
Deprecate old YAML format for buildcaches (#33707) 2022-11-04 12:06:42 -07:00
Tamara Dahlgren
d338ac0634
Updates to stand-alone test documentation (#33703) 2022-11-04 18:55:38 +00:00
Greg Becker
17eaf34902
fix requires test for aarch64 (#33656) 2022-11-04 18:12:55 +00:00
Harmen Stoppels
1d4919924d
Add in-place RPATH replacement (#27610)
Whenever the rpath string actually _grows_, it falls back to patchelf,
when it stays the same length or gets shorter, we update it in-place,
padded with null bytes.

This PR only deals with absolute -> absolute rpath replacement. We don't
use `_build_tarball(relative=True)` in our CI. If `relative` then it falls
back to the old replacement code.

With this PR, relocation time goes down significantly, likely because patchelf
does some odd things with mmap, causing lots of overhead. Example:

- `binutils`: 700MB installed, goes from `1.91s` to `0.57s`, or `3.4x` faster.
   Relocation time: 27% -> 10% of total install time
- `llvm`: 6.8GB installed, goes from `28.56s` to `5.38`, or `5.3x` faster.
   Relocation time: 44% -> 13% of total install time

The bottleneck is now decompression.

Note: I'm somewhat confused about the "relative rpath" code paths. Right
now this PR only deals with absolute -> absolute replacement. As far as
I understand, if you embrace relative rpaths when uploading to the
buildcache, the whole point is you _don't_ want to patch rpaths on
install? So it seems fine to not expand `$ORIGIN` again imho.
2022-11-04 02:30:53 -07:00
Jordan Galby
b1f896e6c7
Fix non-parallel make under depfile jobserver (#32862)
When a package asks for non-parallel make, we need to force `make -j1` because just doing `make` will run in parallel under jobserver (e.g. `spack env depfile`).

We now always add `-j1` when asked for a non-parallel execution (even if there is no jobserver).

And each `MakeExecutable` can now ask for jobserver support or not. For example: the default `ninja` does not support jobserver so spack applies the default `-j`, but `ninja@kitware` or `ninja-fortran` does, so spack doesn't add `-j`.

Tips: you can run `SPACK_INSTALL_FLAGS=-j1 make -f spack-env-depfile.make -j8` to avoid massive job-spawning because of build tools that don't support jobserver (ninja).
2022-11-04 02:05:22 -07:00
Todd Gamblin
9c5c327a6f
propagation: don't count propagated variant values as non-default (#33687)
We try to avoid non-default variant values in the concretizer, but this doesn't make
sense for variants forced to take some non-default value by variant propagation.
Counting this as a penalty effectively biases the concretizer for small specs dependency
graphs -- something we try very hard to avoid elsewhere because it can lead to very
strange decisions.

Example: with the penalty, `spack spec hdf5` will choose the default `openmpi` as its
`mpi` provider, but `spack spec hdf5 ~~shared` will choose `mpich` because it has to set
fewer non-default variant values because `mpich`'s DAG is smaller. That's not a good
reason to prefer a non-default virtual provider.

To fix this, if the user explicitly requests a non-default value to be propagated, there
shouldn't be a penalty. Variant values set on the CLI already don't count as default; we
just need to extend that to propagated values.
2022-11-03 18:26:03 -06:00
Harmen Stoppels
b52be75978
Experimental binding of shared ELF libraries (#31948)
Adds another post install hook that loops over the install prefix, looking for shared libraries type of ELF files, and sets the soname to their own absolute paths.

The idea being, whenever somebody links against those libraries, the linker copies the soname (which is the absolute path to the library) as a "needed" library, so that at runtime the dynamic loader realizes the needed library is a path which should be loaded directly without searching.

As a result:

1. rpaths are not used for the fixed/static list of needed libraries in the dynamic section (only for _actually_ dynamically loaded libraries through `dlopen`), which largely solves the issue that Spack's rpaths are a heuristic (`<prefix>/lib` and `<prefix>/lib64` might not be where libraries really are...)
2. improved startup times (no library search required)
2022-11-03 17:34:00 -06:00
Scott Wittenburg
b55509ffa8
gitlab: Prune untouched specs less aggressively (#33669)
Untouched spec pruning was added to reduce the number of specs
developers see getting rebuilt in their PR pipelines that they
don't understand.  Because the state of the develop mirror lags
quite far behind the tip of the develop branch, PRs often find
they need to rebuild things untouched by their PR.

Untouched spec pruning was previously implemented by finding all
specs in the environment with names of packages touched by the PR,
traversing in both directions the DAGS of those specs, and adding
all dependencies as well as dependents to a list of concrete specs
that should not be considered for pruning.

We found that this heuristic results in too many pruned specs, and
that dependents of touched specs must have all their dependencies
added to the list of specs that should not be considered for pruning.
2022-11-03 13:33:52 -06:00
Harmen Stoppels
243dfe91e9
Use spack.traverse.traverse_nodes where useful (#33677) 2022-11-03 11:34:24 +01:00
Massimiliano Culpo
0d82688903
Update metadata for bootstrapping (#33665) 2022-11-03 09:05:03 +00:00
Greg Becker
c716c6ca95
Bugfix for spec objects modified by flag handlers (#33682)
This issue was introduced in #29761:

```
==> Installing ncurses-6.3-22hz6q6cvo3ep2uhrs3erpp2kogxncbn
==> No binary for ncurses-6.3-22hz6q6cvo3ep2uhrs3erpp2kogxncbn found: installing from source
==> Using cached archive: /spack/var/spack/cache/_source-cache/archive/97/97fc51ac2b085d4cde31ef4d2c3122c21abc217e9090a43a30fc5ec21684e059.tar.gz
==> No patches needed for ncurses
==> ncurses: Executing phase: 'autoreconf'
==> ncurses: Executing phase: 'configure'
==> ncurses: Executing phase: 'build'
==> ncurses: Executing phase: 'install'
==> Error: AttributeError: 'str' object has no attribute 'propagate'

The 'ncurses' package cannot find an attribute while trying to build from sources. This might be due to a change in Spack's package format to support multiple build-systems for a single package. You can fix this by updating the build recipe, and you can also report the issue as a bug. More information at https://spack.readthedocs.io/en/latest/packaging_guide.html#installation-procedure

/spack/lib/spack/spack/build_environment.py:1075, in _setup_pkg_and_run:
       1072        tb_string = traceback.format_exc()
       1073
       1074        # build up some context from the offending package so we can
  >>   1075        # show that, too.
       1076        package_context = get_package_context(tb)
       1077
       1078        logfile = None
```

It turns out this was caused by a bug that had been around much longer, in which the flags were passed by reference to the flag_handler, and the flag_handler was modifying the spec object, not just the flags given to the build system. The scope of this bug was limited by the forking model in Spack, which is how it went under the radar for so long.

PR includes regression test.
2022-11-02 21:09:43 -07:00
Harmen Stoppels
b652fe72d7
remove deptype_query remnants and fix incorrect deptypes kwarg (#33670)
* remove deptype_query remnants
* deptypes -> deptype

These arguments haven't existed since 2017, but `traverse` now fails on unknown **kwargs, so they have finally popped up.
2022-11-02 14:24:59 -07:00
Gregory Becker
aa4f478ab8 propagation: improve performance
This updates the propagation logic used in `concretize.lp` to avoid rules with `path()`
in the body and instead base propagation around `depends_on()`.
2022-11-02 09:43:57 -07:00
Kayla Butler
bc209c470d flags/variants: Add ++/~~/== syntax for propagation to dependencies
Currently, compiler flags and variants are inconsistent: compiler flags set for a
package are inherited by its dependencies, while variants are not. We should have these
be consistent by allowing for inheritance to be enabled or disabled for both variants
and compiler flags.

- [x] Make new (spec language) operators
- [x] Apply operators to variants and compiler flags
- [x] Conflicts currently result in an unsatisfiable spec
      (i.e., you can't propagate two conflicting values)

What I propose is using two of the currently used sigils to symbolized that the variant
or compiler flag will be inherited:

Example syntax:
- `package ++variant`
      enabled variant that will be propagated to dependencies
- `package +variant`
      enabled variant that will NOT be propagated to dependencies
- `package ~~variant`
      disabled variant that will be propagated to dependencies
- `package ~variant`
      disabled variant that will NOT be propagated to dependencies
- `package cflags==True`
      `cflags` will be propagated to dependencies
- `package cflags=True`
      `cflags` will NOT be propagated to dependencies

Syntax for string-valued variants is similar to compiler flags.
2022-11-02 09:43:57 -07:00
Todd Gamblin
a4d978be59
tests: fix group membership check in sbang tests. (#33658)
Fixes an issue on the RHEL8 UBI container where this test would fail because `gr_mem`
was empty for every entry in the `grp` DB.

You have to check *both* the `pwd` database (which has primary groups) and `grp` (which
has other gorups) to do this correctly.

- [x] update `llnl.util.filesystem.group_ids()` to do this
- [x] use it in the `sbang` test
2022-11-02 11:00:16 +01:00
Harmen Stoppels
4bad9f9b13
Consolidate DAG traversal in traverse.py, support DFS/BFS (#33406)
This PR introduces breadth-first traversal, and moves depth-first traversal
logic out of Spec's member functions, into `traverse.py`.

It introduces a high-level API with three main methods:

```python
spack.traverse.traverse_edges(specs, kwargs...)
spack.traverse.traverse_nodes(specs, kwags...)
spack.traverse.traverse_tree(specs, kwargs...)
```

with the usual `root`, `order`, `cover`, `direction`, `deptype`, `depth`, `key`,
`visited` kwargs for the first two.

What's new is that `order="breadth"` is added for breadth-first traversal.

The lower level API is not exported, but is certainly useful for advanced use
cases. The lower level API includes visitor classes for direction reversal and
edge pruning, which can be used to create more advanced traversal methods,
especially useful when the `deptype` is not constant but depends on the node
or depth. 

---

There's a couple nice use-cases for breadth-first traversal:

- Sometimes roots have to be handled differently (e.g. follow build edges of
  roots but not of deps). BFS ensures that root nodes are always discovered at
  depth 0, instead of at any depth > 1 as a dep of another root.
- When printing a tree, it would be nice to reduce indent levels so it fits in the 
  terminal, and ensure that e.g. `zlib` is not printed at indent level 10 as a 
  dependency of a build dep of a build dep -- rather if it's a direct dep of my
  package, I wanna see it at depth 1. This basically requires one breadth-first
  traversal to construct a tree, which can then be printed with depth-first traversal.
- In environments in general, it's sometimes inconvenient to have a double
  loop: first over the roots then over each root's deps, and maintain your own
  `visited` set outside. With BFS, you can simply init the queue with the
  environment root specs and it Just Works. [Example here](3ec7304699/lib/spack/spack/environment/environment.py (L1815-L1816))
2022-11-01 23:04:47 -07:00