[SPARK-37137][PYTHON] Inline type hints for python/pyspark/conf.py

### What changes were proposed in this pull request?

Inline type hints for python/pyspark/conf.py

### Why are the changes needed?

Currently, Inline type hints for python/pyspark/conf.pyi doesn't support type checking within function bodies. So we inline type hints to support that.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Exising test.

Closes #34411 from ByronHsu/SPARK-37137.

Authored-by: Byron <[email protected]>
Signed-off-by: Hyukjin Kwon <[email protected]>

Author: ByronHsu

python/pyspark/conf.py

@@ -18,10 +18,12 @@
 __all__ = ['SparkConf']
 
 import sys
+from typing import Dict, List, Optional, Tuple, cast, overload
 
+from py4j.java_gateway import JVMView, JavaObject  # type: ignore[import]
 
-class SparkConf(object):
 
+class SparkConf(object):
     """
     Configuration for a Spark application. Used to set various Spark
     parameters as key-value pairs.
@@ -105,15 +107,19 @@ class SparkConf(object):
     spark.home=/path
     """
 
-    def __init__(self, loadDefaults=True, _jvm=None, _jconf=None):
+    _jconf: Optional[JavaObject]
+    _conf: Optional[Dict[str, str]]
+
+    def __init__(self, loadDefaults: bool = True, _jvm: Optional[JVMView] = None,
+                 _jconf: Optional[JavaObject] = None):
         """
         Create a new Spark configuration.
         """
         if _jconf:
             self._jconf = _jconf
         else:
             from pyspark.context import SparkContext
-            _jvm = _jvm or SparkContext._jvm
+            _jvm = _jvm or SparkContext._jvm  # type: ignore[attr-defined]
 
             if _jvm is not None:
                 # JVM is created, so create self._jconf directly through JVM
@@ -124,48 +130,58 @@ def __init__(self, loadDefaults=True, _jvm=None, _jconf=None):
                 self._jconf = None
                 self._conf = {}
 
-    def set(self, key, value):
+    def set(self, key: str, value: str) -> "SparkConf":
         """Set a configuration property."""
         # Try to set self._jconf first if JVM is created, set self._conf if JVM is not created yet.
         if self._jconf is not None:
             self._jconf.set(key, str(value))
         else:
+            assert self._conf is not None
             self._conf[key] = str(value)
         return self
 
-    def setIfMissing(self, key, value):
+    def setIfMissing(self, key: str, value: str) -> "SparkConf":
         """Set a configuration property, if not already set."""
         if self.get(key) is None:
             self.set(key, value)
         return self
 
-    def setMaster(self, value):
+    def setMaster(self, value: str) -> "SparkConf":
         """Set master URL to connect to."""
         self.set("spark.master", value)
         return self
 
-    def setAppName(self, value):
+    def setAppName(self, value: str) -> "SparkConf":
         """Set application name."""
         self.set("spark.app.name", value)
         return self
 
-    def setSparkHome(self, value):
+    def setSparkHome(self, value: str) -> "SparkConf":
         """Set path where Spark is installed on worker nodes."""
         self.set("spark.home", value)
         return self
 
-    def setExecutorEnv(self, key=None, value=None, pairs=None):
+    @overload
+    def setExecutorEnv(self, key: str, value: str) -> "SparkConf":
+        ...
+
+    @overload
+    def setExecutorEnv(self, *, pairs: List[Tuple[str, str]]) -> "SparkConf":
+        ...
+
+    def setExecutorEnv(self, key: Optional[str] = None, value: Optional[str] = None,
+                       pairs: Optional[List[Tuple[str, str]]] = None) -> "SparkConf":
         """Set an environment variable to be passed to executors."""
         if (key is not None and pairs is not None) or (key is None and pairs is None):
             raise RuntimeError("Either pass one key-value pair or a list of pairs")
         elif key is not None:
-            self.set("spark.executorEnv." + key, value)
+            self.set("spark.executorEnv.{}".format(key), cast(str, value))
         elif pairs is not None:
             for (k, v) in pairs:
-                self.set("spark.executorEnv." + k, v)
+                self.set("spark.executorEnv.{}".format(k), v)
         return self
 
-    def setAll(self, pairs):
+    def setAll(self, pairs: List[Tuple[str, str]]) -> "SparkConf":
         """
         Set multiple parameters, passed as a list of key-value pairs.
 
@@ -178,49 +194,52 @@ def setAll(self, pairs):
             self.set(k, v)
         return self
 
-    def get(self, key, defaultValue=None):
+    def get(self, key: str, defaultValue: Optional[str] = None) -> Optional[str]:
         """Get the configured value for some key, or return a default otherwise."""
-        if defaultValue is None:   # Py4J doesn't call the right get() if we pass None
+        if defaultValue is None:  # Py4J doesn't call the right get() if we pass None
             if self._jconf is not None:
                 if not self._jconf.contains(key):
                     return None
                 return self._jconf.get(key)
             else:
-                if key not in self._conf:
-                    return None
-                return self._conf[key]
+                assert self._conf is not None
+                return self._conf.get(key, None)
         else:
             if self._jconf is not None:
                 return self._jconf.get(key, defaultValue)
             else:
+                assert self._conf is not None
                 return self._conf.get(key, defaultValue)
 
-    def getAll(self):
+    def getAll(self) -> List[Tuple[str, str]]:
         """Get all values as a list of key-value pairs."""
         if self._jconf is not None:
-            return [(elem._1(), elem._2()) for elem in self._jconf.getAll()]
+            return [(elem._1(), elem._2()) for elem in cast(JavaObject, self._jconf).getAll()]
         else:
-            return self._conf.items()
+            assert self._conf is not None
+            return list(self._conf.items())
 
-    def contains(self, key):
+    def contains(self, key: str) -> bool:
         """Does this configuration contain a given key?"""
         if self._jconf is not None:
             return self._jconf.contains(key)
         else:
+            assert self._conf is not None
             return key in self._conf
 
-    def toDebugString(self):
+    def toDebugString(self) -> str:
         """
         Returns a printable version of the configuration, as a list of
         key=value pairs, one per line.
         """
         if self._jconf is not None:
             return self._jconf.toDebugString()
         else:
+            assert self._conf is not None
             return '\n'.join('%s=%s' % (k, v) for k, v in self._conf.items())
 
 
-def _test():
+def _test() -> None:
     import doctest
     (failure_count, test_count) = doctest.testmod(optionflags=doctest.ELLIPSIS)
     if failure_count:

python/pyspark/conf.pyi

@@ -610,7 +610,7 @@ def _create_shell_session() -> "SparkSession":
         try:
             # Try to access HiveConf, it will raise exception if Hive is not added
             conf = SparkConf()
-            if conf.get('spark.sql.catalogImplementation', 'hive').lower() == 'hive':
+            if cast(str, conf.get('spark.sql.catalogImplementation', 'hive')).lower() == 'hive':
                 (SparkContext._jvm  # type: ignore[attr-defined]
                  .org.apache.hadoop.hive.conf.HiveConf())
                 return SparkSession.builder\
@@ -619,7 +619,7 @@ def _create_shell_session() -> "SparkSession":
             else:
                 return SparkSession.builder.getOrCreate()
         except (py4j.protocol.Py4JError, TypeError):
-            if conf.get('spark.sql.catalogImplementation', '').lower() == 'hive':
+            if cast(str, conf.get('spark.sql.catalogImplementation', '')).lower() == 'hive':
                 warnings.warn("Fall back to non-hive support because failing to access HiveConf, "
                               "please make sure you build spark with hive")