Add SafeCloseable context manager wrapper (#5251)

* Add SafeCloseable wrapper

* Add SafeCloseable test

* Extend JObjectWrapper

* Polish

* Polish

* Apply suggestions from code review

Per @chipkent.

Co-authored-by: Chip Kent <5250374+chipkent@users.noreply.github.com>

* Document assumption

* Polish pydoc

Co-authored-by: Chip Kent <5250374+chipkent@users.noreply.github.com>

* Change SafeCloseable to AutoCloseable

---------

Co-authored-by: Chip Kent <5250374+chipkent@users.noreply.github.com>

py/server/deephaven/jcompat.py

@@ -12,7 +12,7 @@
 import pandas as pd
 
 from deephaven import dtypes, DHError
-from deephaven._wrapper import unwrap, wrap_j_object
+from deephaven._wrapper import unwrap, wrap_j_object, JObjectWrapper
 from deephaven.dtypes import DType, _PRIMITIVE_DTYPE_NULL_MAP, _J_ARRAY_NP_TYPE_MAP
 
 _NULL_BOOLEAN_AS_BYTE = jpy.get_type("io.deephaven.util.BooleanUtils").NULL_BOOLEAN_AS_BYTE
@@ -304,3 +304,33 @@ def _j_array_to_series(dtype: DType, j_array: jpy.JType, conv_null: bool) -> pd.
  s = pd.Series(data=np_array, copy=False)
 
  return s
+
+
+class AutoCloseable(JObjectWrapper):
+ """A context manager wrapper to allow Java AutoCloseable to be used in with statements.
+ 
+ When constructing a new instance, the Java AutoCloseable must not be closed."""
+
+ j_object_type = jpy.get_type("java.lang.AutoCloseable")
+
+ def __init__(self, j_auto_closeable):
+ self._j_auto_closeable = j_auto_closeable
+ self.closed = False
+
+ def __enter__(self):
+ return self
+
+ def close(self):
+ if not self.closed:
+ self.closed = True
+ self._j_auto_closeable.close()
+
+ def __exit__(self, exc_type, exc_value, traceback):
+ self.close()
+
+ def __del__(self):
+ self.close()
+
+ @property
+ def j_object(self) -> jpy.JType:
+ return self._j_auto_closeable

py/server/tests/test_jcompat.py

@@ -5,11 +5,12 @@
 import unittest
 
 from deephaven import dtypes
-from deephaven.jcompat import j_function, j_lambda
+from deephaven.jcompat import j_function, j_lambda, AutoCloseable
 from tests.testbase import BaseTestCase
 
 import jpy
 
+_JSharedContext = jpy.get_type("io.deephaven.engine.table.SharedContext")
 
 class JCompatTestCase(BaseTestCase):
  def test_j_function(self):
@@ -29,6 +30,12 @@ def int_to_str(v: int) -> str:
  r = j_func.apply(10)
  self.assertEqual(r, "10")
 
+ def test_auto_closeable(self):
+ auto_closeable = AutoCloseable(_JSharedContext.makeSharedContext())
+ with auto_closeable:
+ self.assertEqual(auto_closeable.closed, False)
+ self.assertEqual(auto_closeable.closed, True)
+
 
 if __name__ == "__main__":
  unittest.main()