import functools
import gc
import itertools
import os
import subprocess
from contextlib import contextmanager
from typing import Any
import petsc4py
from mpi4py import MPI
from petsc4py import PETSc
from pyop2 import mpi
__all__ = ("PETSc", "OptionsManager", "get_petsc_variables")
class FiredrakePETScError(Exception):
pass
def flatten_parameters(parameters, sep="_"):
"""Flatten a nested parameters dict, joining keys with sep.
:arg parameters: a dict to flatten.
:arg sep: separator of keys.
Used to flatten parameter dictionaries with nested structure to a
flat dict suitable to pass to PETSc. For example:
.. code-block:: python3
flatten_parameters({"a": {"b": {"c": 4}, "d": 2}, "e": 1}, sep="_")
=> {"a_b_c": 4, "a_d": 2, "e": 1}
If a "prefix" key already ends with the provided separator, then
it is not used to concatenate the keys. Hence:
.. code-block:: python3
flatten_parameters({"a_": {"b": {"c": 4}, "d": 2}, "e": 1}, sep="_")
=> {"a_b_c": 4, "a_d": 2, "e": 1}
# rather than
=> {"a__b_c": 4, "a__d": 2, "e": 1}
"""
from firedrake.logging import warning
new = type(parameters)()
if not len(parameters):
return new
def flatten(parameters, *prefixes):
"""Iterate over nested dicts, yielding (*keys, value) pairs."""
sentinel = object()
try:
option = sentinel
for option, value in parameters.items():
# Recurse into values to flatten any dicts.
for pair in flatten(value, option, *prefixes):
yield pair
# Make sure zero-length dicts come back.
if option is sentinel:
yield (prefixes, parameters)
except AttributeError:
# Non dict values are just returned.
yield (prefixes, parameters)
def munge(keys):
"""Ensure that each intermediate key in keys ends in sep.
Also, reverse the list."""
for key in reversed(keys[1:]):
if len(key) and not key.endswith(sep):
yield key + sep
else:
yield key
else:
yield keys[0]
for keys, value in flatten(parameters):
option = "".join(map(str, munge(keys)))
if option in new:
warning("Ignoring duplicate option: %s (existing value %s, new value %s)",
option, new[option], value)
new[option] = value
return new
[docs]
@functools.lru_cache()
def get_petsc_variables():
"""Get dict of PETSc environment variables from the file:
$PETSC_DIR/$PETSC_ARCH/lib/petsc/conf/petscvariables
The result is memoized to avoid constantly reading the file.
"""
config = petsc4py.get_config()
path = [config["PETSC_DIR"], config["PETSC_ARCH"], "lib/petsc/conf/petscvariables"]
variables_path = os.path.join(*path)
with open(variables_path) as fh:
# Split lines on first '=' (assignment)
splitlines = (line.split("=", maxsplit=1) for line in fh.readlines())
return {k.strip(): v.strip() for k, v in splitlines}
def _get_dependencies(filename):
"""Get all the dependencies of a shared object library"""
# Linux uses `ldd` to look at shared library linkage, MacOS uses `otool`
try:
program = ["ldd"]
cmd = subprocess.run([*program, filename], stdout=subprocess.PIPE)
# Filter out the VDSO and the ELF interpreter on Linux
results = [line for line in cmd.stdout.decode("utf-8").split("\n") if "=>" in line]
return [line.split()[2] for line in results]
except FileNotFoundError:
program = ["otool", "-L"]
cmd = subprocess.run([*program, filename], stdout=subprocess.PIPE)
# Meanwhile MacOS puts garbage at the beginning and end of `otool` output
return [line.split()[0] for line in cmd.stdout.decode("utf-8").split("\n")[1:-1]]
def get_blas_library():
"""Get the path to the BLAS library that PETSc links to"""
petsc_py_dependencies = _get_dependencies(PETSc.__file__)
library_names = ["blas", "libmkl"]
for filename in petsc_py_dependencies:
if any(name in filename for name in library_names):
return filename
# On newer MacOS versions, the PETSc Python extension library doesn't link
# to BLAS or MKL directly, so we check the PETSc C library.
petsc_c_library = [f for f in petsc_py_dependencies if "libpetsc" in f][0]
petsc_c_dependencies = _get_dependencies(petsc_c_library)
for filename in petsc_c_dependencies:
if any(name in filename for name in library_names):
return filename
return None
[docs]
class OptionsManager(object):
# What appeared on the commandline, we should never clear these.
# They will override options passed in as a dict if an
# options_prefix was supplied.
commandline_options = frozenset(PETSc.Options().getAll())
options_object = PETSc.Options()
count = itertools.count()
"""Mixin class that helps with managing setting petsc options.
:arg parameters: The dictionary of parameters to use.
:arg options_prefix: The prefix to look up items in the global
options database (may be ``None``, in which case only entries
from ``parameters`` will be considered. If no trailing
underscore is provided, one is appended. Hence ``foo_`` and
``foo`` are treated equivalently. As an exception, if the
prefix is the empty string, no underscore is appended.
To use this, you must call its constructor to with the parameters
you want in the options database.
You then call :meth:`set_from_options`, passing the PETSc object
you'd like to call ``setFromOptions`` on. Note that this will
actually only call ``setFromOptions`` the first time (so really
this parameters object is a once-per-PETSc-object thing).
So that the runtime monitors which look in the options database
actually see options, you need to ensure that the options database
is populated at the time of a ``SNESSolve`` or ``KSPSolve`` call.
Do that using the :meth:`inserted_options` context manager.
.. code-block:: python3
with self.inserted_options():
self.snes.solve(...)
This ensures that the options database has the relevant entries
for the duration of the ``with`` block, before removing them
afterwards. This is a much more robust way of dealing with the
fixed-size options database than trying to clear it out using
destructors.
This object can also be used only to manage insertion and deletion
into the PETSc options database, by using the context manager.
"""
def __init__(self, parameters, options_prefix):
super().__init__()
if parameters is None:
parameters = {}
else:
# Convert nested dicts
parameters = flatten_parameters(parameters)
if options_prefix is None:
self.options_prefix = "firedrake_%d_" % next(self.count)
self.parameters = parameters
self.to_delete = set(parameters)
else:
if len(options_prefix) and not options_prefix.endswith("_"):
options_prefix += "_"
self.options_prefix = options_prefix
# Remove those options from the dict that were passed on
# the commandline.
self.parameters = {k: v for k, v in parameters.items()
if options_prefix + k not in self.commandline_options}
self.to_delete = set(self.parameters)
# Now update parameters from options, so that they're
# available to solver setup (for, e.g., matrix-free).
# Can't ask for the prefixed guy in the options object,
# since that does not DTRT for flag options.
for k, v in self.options_object.getAll().items():
if k.startswith(self.options_prefix):
self.parameters[k[len(self.options_prefix):]] = v
self._setfromoptions = False
[docs]
def set_default_parameter(self, key, val):
"""Set a default parameter value.
:arg key: The parameter name
:arg val: The parameter value.
Ensures that the right thing happens cleaning up the options
database.
"""
k = self.options_prefix + key
if k not in self.options_object and key not in self.parameters:
self.parameters[key] = val
self.to_delete.add(key)
[docs]
def set_from_options(self, petsc_obj):
"""Set up petsc_obj from the options database.
:arg petsc_obj: The PETSc object to call setFromOptions on.
Matt says: "Only ever call setFromOptions once". This
function ensures we do so.
"""
if not self._setfromoptions:
with self.inserted_options():
petsc_obj.setOptionsPrefix(self.options_prefix)
# Call setfromoptions inserting appropriate options into
# the options database.
petsc_obj.setFromOptions()
self._setfromoptions = True
[docs]
@contextmanager
def inserted_options(self):
"""Context manager inside which the petsc options database
contains the parameters from this object."""
try:
for k, v in self.parameters.items():
self.options_object[self.options_prefix + k] = v
yield
finally:
for k in self.to_delete:
del self.options_object[self.options_prefix + k]
def _extract_comm(obj: Any) -> MPI.Comm:
"""Extract and return the Firedrake/PyOP2 internal comm of a given object.
Parameters
----------
obj:
Any Firedrake object or any comm
Returns
-------
MPI.Comm
Internal communicator
"""
comm = None
# If the object is a communicator check whether it is already an internal
# communicator, otherwise get the internal communicator attribute from the
# given communicator.
if isinstance(obj, (PETSc.Comm, mpi.MPI.Comm)):
try:
if mpi.is_pyop2_comm(obj):
comm = obj
else:
internal_comm = obj.Get_attr(mpi.innercomm_keyval)
if internal_comm is None:
comm = obj
else:
comm = internal_comm
except mpi.PyOP2CommError:
pass
elif hasattr(obj, "_comm"):
comm = obj._comm
elif hasattr(obj, "comm"):
comm = obj.comm
return comm
@mpi.collective
def garbage_cleanup(obj: Any):
"""Clean up garbage PETSc objects on a Firedrake object or any comm.
Parameters
----------
obj:
Any Firedrake object with a comm, or any comm
"""
# We are manually calling the Python cyclic garbage collection routine to
# get as many unreachable reference cycles swept up before we call the PETSc
# cleanup routine. This routine is designed to free up as much memory as
# possible for memory constrained systems
gc.collect()
comm = _extract_comm(obj)
if comm:
PETSc.garbage_cleanup(comm)
else:
raise FiredrakePETScError("No comm found, cannot clean up garbage")
@mpi.collective
def garbage_view(obj: Any):
"""View garbage PETSc objects stored on a Firedrake object or any comm.
Parameters
----------
obj:
Any Firedrake object with a comm, or any comm.
"""
# We are manually calling the Python cyclic garbage collection routine so
# that as many unreachable PETSc objects are visible in the garbage view.
gc.collect()
comm = _extract_comm(obj)
if comm:
PETSc.garbage_view(comm)
else:
raise FiredrakePETScError("No comm found, cannot view garbage")
