From a1bf651643a5548316dbfa388ebfa4bf29fed555 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Mon, 2 Sep 2024 09:13:25 +0100
Subject: [PATCH 1/3] fix: use fastpath for PyCapsule export when starting from
 pyarrow-backed Series, respect requested_schema

---
 pandas/core/series.py                       | 16 +++++++++++++--
 pandas/tests/series/test_arrow_interface.py | 22 +++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 4f79e30f48f3c..579227609f387 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -77,6 +77,7 @@
     validate_all_hashable,
 )
 from pandas.core.dtypes.dtypes import (
+    ArrowDtype,
     CategoricalDtype,
     ExtensionDtype,
     SparseDtype,
@@ -580,8 +581,19 @@ def __arrow_c_stream__(self, requested_schema=None):
         PyCapsule
         """
         pa = import_optional_dependency("pyarrow", min_version="16.0.0")
-        ca = pa.chunked_array([pa.Array.from_pandas(self, type=requested_schema)])
-        return ca.__arrow_c_stream__(requested_schema)
+        type = (
+            pa.DataType._import_from_c_capsule(requested_schema)
+            if requested_schema is not None
+            else None
+        )
+        if isinstance(self.dtype, ArrowDtype):
+            # fastpath!
+            ca = self.values._pa_array
+            if type is not None:
+                ca = ca.cast(type)
+        else:
+            ca = pa.chunked_array([pa.Array.from_pandas(self, type=type)])
+        return ca.__arrow_c_stream__()
 
     # ----------------------------------------------------------------------
 
diff --git a/pandas/tests/series/test_arrow_interface.py b/pandas/tests/series/test_arrow_interface.py
index 34a2a638e4185..9f1f0403d23a7 100644
--- a/pandas/tests/series/test_arrow_interface.py
+++ b/pandas/tests/series/test_arrow_interface.py
@@ -21,3 +21,25 @@ def test_series_arrow_interface():
     ca = pa.chunked_array(s)
     expected = pa.chunked_array([[1, 4, 2]])
     assert ca.equals(expected)
+    ca = pa.chunked_array(s, type=pa.int32())
+    expected = pa.chunked_array([[1, 4, 2]], type=pa.int32())
+    assert ca.equals(expected)
+
+
+def test_series_arrow_interface_arrow_dtypes():
+    s = pd.Series([1, 4, 2], dtype="Int64[pyarrow]")
+
+    capsule = s.__arrow_c_stream__()
+    assert (
+        ctypes.pythonapi.PyCapsule_IsValid(
+            ctypes.py_object(capsule), b"arrow_array_stream"
+        )
+        == 1
+    )
+
+    ca = pa.chunked_array(s)
+    expected = pa.chunked_array([[1, 4, 2]])
+    assert ca.equals(expected)
+    ca = pa.chunked_array(s, type=pa.int32())
+    expected = pa.chunked_array([[1, 4, 2]], type=pa.int32())
+    assert ca.equals(expected)

From 04871d4e87bbc2c418747c8ed45cd75d29bb49af Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Fri, 6 Sep 2024 14:10:14 +0100
Subject: [PATCH 2/3] simplify

---
 pandas/core/series.py | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 579227609f387..0c26ce27c680c 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -77,7 +77,6 @@
     validate_all_hashable,
 )
 from pandas.core.dtypes.dtypes import (
-    ArrowDtype,
     CategoricalDtype,
     ExtensionDtype,
     SparseDtype,
@@ -586,13 +585,9 @@ def __arrow_c_stream__(self, requested_schema=None):
             if requested_schema is not None
             else None
         )
-        if isinstance(self.dtype, ArrowDtype):
-            # fastpath!
-            ca = self.values._pa_array
-            if type is not None:
-                ca = ca.cast(type)
-        else:
-            ca = pa.chunked_array([pa.Array.from_pandas(self, type=type)])
+        ca = pa.array(self, type=type)
+        if not isinstance(ca, pa.ChunkedArray):
+            ca = pa.chunked_array([ca])
         return ca.__arrow_c_stream__()
 
     # ----------------------------------------------------------------------

From bf33163a39edf914ed482d02702ed3c23a24bc3f Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Fri, 6 Sep 2024 14:13:49 +0100
Subject: [PATCH 3/3] stringdtype test

---
 pandas/tests/series/test_arrow_interface.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/pandas/tests/series/test_arrow_interface.py b/pandas/tests/series/test_arrow_interface.py
index 9f1f0403d23a7..e73cf9bee6aeb 100644
--- a/pandas/tests/series/test_arrow_interface.py
+++ b/pandas/tests/series/test_arrow_interface.py
@@ -43,3 +43,19 @@ def test_series_arrow_interface_arrow_dtypes():
     ca = pa.chunked_array(s, type=pa.int32())
     expected = pa.chunked_array([[1, 4, 2]], type=pa.int32())
     assert ca.equals(expected)
+
+
+def test_series_arrow_interface_stringdtype():
+    s = pd.Series(["foo", "bar"], dtype="string[pyarrow]")
+
+    capsule = s.__arrow_c_stream__()
+    assert (
+        ctypes.pythonapi.PyCapsule_IsValid(
+            ctypes.py_object(capsule), b"arrow_array_stream"
+        )
+        == 1
+    )
+
+    ca = pa.chunked_array(s)
+    expected = pa.chunked_array([["foo", "bar"]], type=pa.large_string())
+    assert ca.equals(expected)