REFACTOR-#2059: Consolidate environment variables

.github/workflows/ci.yml

@@ -166,7 +166,11 @@ jobs:
           conda list
       - name: Internals tests
         shell: bash -l {0}
-        run: python -m pytest modin/test/test_publisher.py modin/data_management/factories/test/test_dispatcher.py modin/experimental/cloud/test/test_cloud.py
+        run: python -m pytest modin/data_management/factories/test/test_dispatcher.py modin/experimental/cloud/test/test_cloud.py
+      - shell: bash -l {0}
+        run: python -m pytest modin/config/test
+      - shell: bash -l {0}
+        run: python -m pytest modin/test/test_envvar_catcher.py
 
   test-defaults:
     needs: [lint-commit, lint-flake8, lint-black, test-api, test-headers]

modin/__init__.py

@@ -11,10 +11,7 @@
 # ANY KIND, either express or implied. See the License for the specific language
 # governing permissions and limitations under the License.
 
-import os
 import warnings
-from packaging import version
-import collections
 
 from ._version import get_versions
 
@@ -35,95 +32,6 @@ def custom_formatwarning(msg, category, *args, **kwargs):
 )
 
 
-def get_execution_engine():
-    # In the future, when there are multiple engines and different ways of
-    # backing the DataFrame, there will have to be some changed logic here to
-    # decide these things. In the meantime, we will use the currently supported
-    # execution engine + backing (Pandas + Ray).
-    if "MODIN_ENGINE" in os.environ:
-        # .title allows variants like ray, RAY, Ray
-        return os.environ["MODIN_ENGINE"].title()
-    else:
-        if "MODIN_DEBUG" in os.environ:
-            return "Python"
-        else:
-            try:
-                import ray
-
-            except ImportError:
-                pass
-            else:
-                if version.parse(ray.__version__) < version.parse("1.0.0"):
-                    raise ImportError(
-                        "Please `pip install modin[ray]` to install compatible Ray version."
-                    )
-                return "Ray"
-            try:
-                import dask
-                import distributed
-
-            except ImportError:
-                raise ImportError(
-                    "Please `pip install modin[ray]` or `modin[dask]` to install an engine"
-                )
-            else:
-                if version.parse(dask.__version__) < version.parse(
-                    "2.1.0"
-                ) or version.parse(distributed.__version__) < version.parse("2.3.2"):
-                    raise ImportError(
-                        "Please `pip install modin[dask]` to install compatible Dask version."
-                    )
-                return "Dask"
-
-
-def get_partition_format():
-    # See note above about engine + backing.
-    return os.environ.get("MODIN_BACKEND", "Pandas").title()
-
-
-class Publisher(object):
-    def __init__(self, name, value):
-        self.name = name
-        self.__value = value.title()
-        self.__subs = []
-        self.__once = collections.defaultdict(list)
-
-    def subscribe(self, callback):
-        self.__subs.append(callback)
-        callback(self)
-
-    def once(self, onvalue, callback):
-        onvalue = onvalue.title()
-        if onvalue == self.__value:
-            callback(self)
-        else:
-            self.__once[onvalue].append(callback)
-
-    def get(self):
-        return self.__value
-
-    def _put_nocallback(self, value):
-        value = value.title()  # normalize the value
-        oldvalue, self.__value = self.__value, value
-        return oldvalue
-
-    def _check_callbacks(self, oldvalue):
-        if oldvalue == self.__value:
-            return
-        for callback in self.__subs:
-            callback(self)
-        once = self.__once.pop(self.__value, ())
-        for callback in once:
-            callback(self)
-
-    def put(self, value):
-        self._check_callbacks(self._put_nocallback(value))
-
-
-execution_engine = Publisher(name="execution_engine", value=get_execution_engine())
-partition_format = Publisher(name="partition_format", value=get_partition_format())
-
-
 def set_backends(engine=None, partition=None):
     """
     Method to set the _pair_ of execution engine and partition format simultaneously.
@@ -132,24 +40,22 @@ def set_backends(engine=None, partition=None):
 
     The method returns pair of old values, so it is easy to return back.
     """
+    from .config import Engine, Backend
+
     old_engine, old_partition = None, None
     # defer callbacks until both entities are set
     if engine is not None:
-        old_engine = execution_engine._put_nocallback(engine)
+        old_engine = Engine._put_nocallback(engine)
     if partition is not None:
-        old_partition = partition_format._put_nocallback(partition)
+        old_partition = Backend._put_nocallback(partition)
     # execute callbacks if something was changed
     if old_engine is not None:
-        execution_engine._check_callbacks(old_engine)
+        Engine._check_callbacks(old_engine)
     if old_partition is not None:
-        partition_format._check_callbacks(old_partition)
+        Backend._check_callbacks(old_partition)
 
     return old_engine, old_partition
 
 
-# We don't want these used outside of this file.
-del get_execution_engine
-del get_partition_format
-
 __version__ = get_versions()["version"]
 del get_versions

modin/config/__init__.py

@@ -0,0 +1,15 @@
+# Licensed to Modin Development Team under one or more contributor license agreements.
+# See the NOTICE file distributed with this work for additional information regarding
+# copyright ownership.  The Modin Development Team licenses this file to you under the
+# Apache License, Version 2.0 (the "License"); you may not use this file except in
+# compliance with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software distributed under
+# the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
+# ANY KIND, either express or implied. See the License for the specific language
+# governing permissions and limitations under the License.
+
+from .pubsub import Parameter  # noqa: F401
+from .envvars import *  # noqa: F403, F401

modin/config/__main__.py

@@ -0,0 +1,26 @@
+# Licensed to Modin Development Team under one or more contributor license agreements.
+# See the NOTICE file distributed with this work for additional information regarding
+# copyright ownership.  The Modin Development Team licenses this file to you under the
+# Apache License, Version 2.0 (the "License"); you may not use this file except in
+# compliance with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software distributed under
+# the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
+# ANY KIND, either express or implied. See the License for the specific language
+# governing permissions and limitations under the License.
+
+from . import *  # noqa: F403, F401
+from .pubsub import Parameter
+
+
+def print_config_help():
+    for objname in sorted(globals()):
+        obj = globals()[objname]
+        if isinstance(obj, type) and issubclass(obj, Parameter) and not obj.is_abstract:
+            print(f"{obj.get_help()}\n\tCurrent value: {obj.get()}")  # noqa: T001
+
+
+if __name__ == "__main__":
+    print_config_help()