Deprecate passing 'appctx' to solve

firedrake/solving_utils.py

@@ -1,6 +1,7 @@
 from itertools import chain
 
 import numpy
+import petsctools
 import ufl
 
 from pyop2 import op2
@@ -131,7 +132,7 @@ def check_snes_convergence(snes):
    %s""" % (snes.getIterationNumber(), msg))
 
 
-class _SNESContext(object):
+class _SNESContext:
     """Context holding information for SNES callbacks.
 
     Parameters
@@ -152,9 +153,6 @@ class _SNESContext(object):
     sub_pmat_type
         Indicates the matrix type for the sparse blocks in the preconditioner
         if pmat_type='nest', ignored otherwise.
-    appctx
-        Any extra information used in the assembler.  For the
-        matrix-free case this will contain the Newton state in ``"state"``.
     pre_jacobian_callback
         User-defined function called immediately before Jacobian assembly.
     post_jacobian_callback
@@ -171,6 +169,8 @@ class _SNESContext(object):
     pre_apply_bcs
         If `False`, the problem is linearised around the initial guess before
         imposing the boundary conditions.
+    legacy_appctx_prefix
+        Options prefix used to find appctx entries passed in the legacy fashion.
 
     The idea here is that the SNES holds a shell DM which contains
     this object as "user context".  When the SNES calls back to the
@@ -184,12 +184,12 @@ def __init__(self, problem,
                  mat_type: str, pmat_type: str,
                  sub_mat_type: str | None = None,
                  sub_pmat_type: str | None = None,
-                 appctx: dict | None = None,
                  pre_jacobian_callback=None, pre_function_callback=None,
                  post_jacobian_callback=None, post_function_callback=None,
                  options_prefix: str | None = None,
                  transfer_manager=None,
-                 pre_apply_bcs: bool = True):
+                 pre_apply_bcs: bool = True,
+                 legacy_appctx_prefix: str | None = None):
         from firedrake.assemble import get_assembler
 
         if pmat_type is None:
@@ -216,17 +216,7 @@ def __init__(self, problem,
         # Function to hold current guess
         self._x = problem.u_restrict
 
-        if appctx is None:
-            appctx = {}
-        # A split context will already get the full state.
-        # TODO, a better way of doing this.
-        # Now we don't have a temporary state inside the snes
-        # context we could just require the user to pass in the
-        # full state on the outside.
-        appctx.setdefault("state", self._x)
-        appctx.setdefault("form_compiler_parameters", self.fcp)
-
-        self.appctx = appctx
+        self.legacy_appctx_prefix = legacy_appctx_prefix
         self.matfree = matfree
         self.pmatfree = pmatfree
         self.F = problem.F
@@ -286,10 +276,10 @@ def reconstruct(self, problem=None, mat_type=None, pmat_type=None, **kwargs):
         default_options = {
             "sub_mat_type": self.sub_mat_type,
             "sub_pmat_type": self.sub_pmat_type,
-            "appctx": self.appctx,
             "options_prefix": self.options_prefix,
             "transfer_manager": self.transfer_manager,
             "pre_apply_bcs": self.pre_apply_bcs,
+            "legacy_appctx_prefix": self.legacy_appctx_prefix,
         }
         for k, v in default_options.items():
             if kwargs.get(k) is None:
@@ -342,6 +332,23 @@ def transfer_manager(self, manager):
             raise ValueError("Must set transfer manager before first use.")
         self._transfer_manager = manager
 
+    # TODO: remove this method eventually
+    @cached_property
+    def appctx(self) -> dict:
+        ctx = petsctools.AppContext(self.legacy_appctx_prefix).getAll()
+
+        # A split context will already get the full state.
+        # TODO, a better way of doing this.
+        # Now we don't have a temporary state inside the snes
+        # context we could just require the user to pass in the
+        # full state on the outside.
+        if "state" not in ctx:
+            ctx["state"] = self._x
+        if "form_compiler_parameters" not in ctx:
+            ctx["form_compiler_parameters"] = self.fcp
+
+        return ctx
+
     def set_function(self, snes):
         r"""Set the residual evaluation function"""
         with self._F.dat.vec_wo as v:

firedrake/variational_solver.py

@@ -170,6 +170,17 @@ def compute_bc_lifting(J: ufl.BaseForm | slate.TensorBase,
         return F
 
 
+_solver_id = -1
+"""A unique number for each variational solver.
+
+This is used to uniquely key appctx entries (now deprecated practice).
+
+The fact that this value is not parallel safe is not a concern because PETSc
+options are only read rank-locally.
+
+"""
+
+
 class NonlinearVariationalSolver(NonlinearVariationalSolverMixin):
     r"""Solves a :class:`NonlinearVariationalProblem`."""
 
@@ -259,6 +270,9 @@ def update_diffusivity(current_solution):
                                                 pre_jacobian_callback=update_diffusivity)
 
         """
+        global _solver_id
+        _solver_id += 1
+
         assert isinstance(problem, NonlinearVariationalProblem)
 
         solver_parameters = flatten_parameters(solver_parameters or {})
@@ -278,10 +292,17 @@ def update_diffusivity(current_solution):
                                                        ksp_defaults=self.DEFAULT_KSP_PARAMETERS,
                                                        snes_defaults=self.DEFAULT_SNES_PARAMETERS)
 
+        # Move entries from the deprecated appctx into the parameter dictionary
+        if appctx is not None:
+            legacy_appctx_prefix = f"firedrake_legacy_appctx_{_solver_id}_"
+            for key, value in appctx:
+                solver_parameters[f"{legacy_appctx_prefix}_{key}"] = value
+        else:
+            legacy_appctx_prefix = None
+
         self.options_manager = OptionsManager(solver_parameters, options_prefix,
                                               default_prefix="firedrake")
-        # Now the correct parameters live in self.parameters (via the
-        # OptionsManager mixin)
+        # Now the correct parameters live in self.parameters
         mat_type = self.parameters.get("mat_type")
         pmat_type = self.parameters.get("pmat_type")
         sub_mat_type = self.parameters.get("sub_mat_type")
@@ -291,13 +312,13 @@ def update_diffusivity(current_solution):
                                          pmat_type=pmat_type,
                                          sub_mat_type=sub_mat_type,
                                          sub_pmat_type=sub_pmat_type,
-                                         appctx=appctx,
                                          pre_jacobian_callback=pre_jacobian_callback,
                                          pre_function_callback=pre_function_callback,
                                          post_jacobian_callback=post_jacobian_callback,
                                          post_function_callback=post_function_callback,
                                          options_prefix=self.options_prefix,
-                                         pre_apply_bcs=pre_apply_bcs)
+                                         pre_apply_bcs=pre_apply_bcs,
+                                         legacy_appctx_prefix=legacy_appctx_prefix)
 
         self.snes = PETSc.SNES().create(comm=problem.dm.comm)
 

pyproject.toml

@@ -33,7 +33,7 @@ dependencies = [
   "packaging",
   # TODO RELEASE
   # "petsc4py==3.25.0",
-  "petsctools>=2026.0",
+  "petsctools @ git+https://github.com/firedrakeproject/petsctools@connorjward/appctx-getall",
   "pkgconfig",
   "progress",
   "pyadjoint-ad>=2026.4.0",

requirements-build.txt

@@ -6,7 +6,7 @@ mpi4py>3; python_version >= '3.13'
 mpi4py; python_version < '3.13'
 numpy
 pkgconfig
-petsctools
+petsctools @ git+https://github.com/firedrakeproject/petsctools@connorjward/appctx-getall
 pybind11
 setuptools>=77.0.3