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Set intermediate_solutions explicitly and other small improvements #196

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Merged
Dekker1 merged 3 commits into from
Feb 25, 2025
Merged

Set intermediate_solutions explicitly and other small improvements #196

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71837e2
Allow explicitly setting intermediate_solutions to False
Dekker1 Feb 25, 2025
c4fce6f
Resolve warning about "never awaited" solve_async in test cases
Dekker1 Feb 25, 2025
334a036
Small improvements in scoping and type assertions
Dekker1 Feb 25, 2025
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3 changes: 3 additions & 0 deletions CHANGELOG.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,9 @@ Changed
``Instance.solve``, ``Instance.solve_async``, and ``Instance.solutions``. The
``timeout`` parameter is still accepted, but will add a
``DeprecationWarning`` and will be removed in future versions.
- The ``intermediate_solutions`` parameter can now be explicitly set to
``False`` to avoid the ``-i`` flag to be passed to MiniZinc, which is
generally added to ensure that a final solution is available.

Fixed
^^^^^
Expand Down
69 changes: 42 additions & 27 deletions src/minizinc/instance.py
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Original file line number Diff line number Diff line change
Expand Up @@ -110,7 +110,7 @@ def solve(
processes: Optional[int] = None,
random_seed: Optional[int] = None,
all_solutions: bool = False,
intermediate_solutions: bool = False,
intermediate_solutions: Optional[bool] = None,
free_search: bool = False,
optimisation_level: Optional[int] = None,
timeout: Optional[timedelta] = None,
Expand Down Expand Up @@ -141,10 +141,13 @@ def solve(
all_solutions (bool): Request to solver to find all solutions. (Only
available on satisfaction problems and when the ``-a`` flag is
supported by the solver)
intermediate_solutions (bool): Request the solver to output any
intermediate solutions that are found during the solving
process. (Only available on optimisation problems and when the
``-a`` flag is supported by the solver)
intermediate_solutions (Optional[bool]): Request the solver to
output any intermediate solutions that are found during the
solving process. If left to ``None``, then intermediate
solutions might still be requested to ensure that the solving
process gives its final solution. (Only available on
optimisation problems and when the ``-i`` or ``-a`` flag is
supported by the solver)
optimisation_level (Optional[int]): Set the MiniZinc compiler
optimisation level.

Expand Down Expand Up @@ -189,6 +192,8 @@ def solve(
)
return asyncio.run(coroutine)
except RuntimeError as r:
coroutine.close()
del coroutine
if "called from a running event loop" in r.args[0]:
raise RuntimeError(
"the synchronous MiniZinc Python `solve()` method was called from"
Expand All @@ -207,8 +212,8 @@ async def solve_async(
nr_solutions: Optional[int] = None,
processes: Optional[int] = None,
random_seed: Optional[int] = None,
all_solutions=False,
intermediate_solutions=False,
all_solutions: bool = False,
intermediate_solutions: Optional[bool] = None,
free_search: bool = False,
optimisation_level: Optional[int] = None,
timeout: Optional[timedelta] = None,
Expand All @@ -231,14 +236,14 @@ async def solve_async(

"""
status = Status.UNKNOWN
solution = None
statistics: Dict[str, Any] = {}

multiple_solutions = (
all_solutions or intermediate_solutions or nr_solutions is not None
)
if multiple_solutions:
solution = []
solution: Union[Optional[Any], List[Any]] = (
[] if multiple_solutions else None
)

async for result in self.solutions(
time_limit=time_limit,
Expand All @@ -256,6 +261,7 @@ async def solve_async(
statistics.update(result.statistics)
if result.solution is not None:
if multiple_solutions:
assert isinstance(solution, list)
solution.append(result.solution)
else:
solution = result.solution
Expand Down Expand Up @@ -296,12 +302,12 @@ async def diverse_solutions(
"mzn-analyse executable could not be located"
)

try:
# Create a temporary file in which the diversity model (generated by mzn-analyse) is placed
div_file = tempfile.NamedTemporaryFile(
prefix="mzn_div", suffix=".mzn", delete=False
)
# Create a temporary file in which the diversity model (generated by mzn-analyse) is placed
div_file = tempfile.NamedTemporaryFile(
prefix="mzn_div", suffix=".mzn", delete=False
)

try:
# Extract the diversity annotations.
with self.files() as files:
div_anns = mzn_analyse.run(
Expand Down Expand Up @@ -454,8 +460,8 @@ async def solutions(
nr_solutions: Optional[int] = None,
processes: Optional[int] = None,
random_seed: Optional[int] = None,
all_solutions=False,
intermediate_solutions=False,
all_solutions: bool = False,
intermediate_solutions: Optional[bool] = None,
free_search: bool = False,
optimisation_level: Optional[int] = None,
verbose: bool = False,
Expand Down Expand Up @@ -537,12 +543,20 @@ async def solutions(
"Solver does not support the -n-o flag"
)
cmd.extend(["--num-optimal", str(nr_solutions)])
elif (
"-i" not in self._solver.stdFlags
or "-a" not in self._solver.stdFlags
elif intermediate_solutions:
if (
"-i" not in self._solver.stdFlags
and "-a" not in self._solver.stdFlags
):
raise NotImplementedError(
"Solver does not support the -i and -a flags"
)
cmd.append("--intermediate-solutions")
elif (intermediate_solutions is None and time_limit is not None) and (
"-i" in self._solver.stdFlags or "-a" in self._solver.stdFlags
):
# Enable intermediate solutions when possible
# (ensure that solvers always output their best solution)
# Enable intermediate solutions just in case to ensure that there is
# a best solution available at the time limit.
cmd.append("--intermediate-solutions")
# Set number of processes to be used
if processes is not None:
Expand Down Expand Up @@ -596,12 +610,11 @@ async def solutions(

# Run the MiniZinc process
proc = await self._driver._create_process(cmd, solver=solver)
try:
assert isinstance(proc.stderr, asyncio.StreamReader)
assert isinstance(proc.stdout, asyncio.StreamReader)

read_stderr = asyncio.create_task(_read_all(proc.stderr))
assert isinstance(proc.stderr, asyncio.StreamReader)
assert isinstance(proc.stdout, asyncio.StreamReader)
read_stderr = asyncio.create_task(_read_all(proc.stderr))

try:
async for obj in decode_async_json_stream(
proc.stdout, cls=MZNJSONDecoder, enum_map=self._enum_map
):
Expand Down Expand Up @@ -836,6 +849,7 @@ def analyse(self):
if obj["type"] == "interface":
interface = obj
break
assert interface is not None
old_method = self._method_cache
self._method_cache = Method.from_string(interface["method"])
self._input_cache = {}
Expand Down Expand Up @@ -1019,6 +1033,7 @@ def _parse_stream_obj(self, obj, statistics):
if "_checker" in statistics:
tmp["_checker"] = statistics.pop("_checker")

assert self.output_type is not None
solution = self.output_type(**tmp)
statistics["time"] = timedelta(milliseconds=obj["time"])
elif obj["type"] == "time":
Expand Down