tp: add Python API for ExportToArrow

Adds export_to_arrow() to the Python TraceProcessor API which streams
the TAR archive of Arrow IPC files to an output path.

Author: LalitMaganti

python/perfetto/trace_processor/api.py

@@ -272,6 +272,17 @@ def metric(self, metrics: List[str]):
     metrics.ParseFromString(response.metrics)
     return metrics
 
+  def export_to_arrow(self, output_path: str):
+    """Export all intrinsic tables as a TAR archive of Arrow IPC files.
+
+    The archive is streamed directly to disk without materializing in memory.
+
+    Args:
+      output_path: Path to write the TAR archive to.
+    """
+    with open(output_path, 'wb') as f:
+      self.http.export_to_arrow(f)
+
   @property
   def metadata(self) -> Dict[str, str]:
     """Returns metadata associated with this trace.

python/perfetto/trace_processor/http.py

@@ -106,3 +106,13 @@ def disable_and_read_metatrace(self):
       result = self.protos.DisableAndReadMetatraceResult()
       result.ParseFromString(f.read())
       return result
+
+  def export_to_arrow(self, output_file):
+    """Streams the arrow TAR archive directly to an open file object."""
+    self.conn.request('POST', '/export_to_arrow')
+    with self.conn.getresponse() as f:
+      while True:
+        chunk = f.read(65536)
+        if not chunk:
+          break
+        output_file.write(chunk)

python/test/api_integrationtest.py

@@ -646,3 +646,30 @@ def resolve(self):
           '_path': example_android_trace_path()
       }
       self.assertEqual(tp.metadata, expected_metadata)
+
+  def test_export_to_arrow(self):
+    import tarfile
+    with create_tp(trace=example_android_trace_path()) as tp:
+      with tempfile.NamedTemporaryFile(suffix='.tar', delete=False) as f:
+        output_path = f.name
+      try:
+        tp.export_to_arrow(output_path)
+
+        # Verify the output is a valid TAR archive.
+        self.assertTrue(tarfile.is_tarfile(output_path))
+
+        with tarfile.open(output_path) as tf:
+          names = tf.getnames()
+          # Should contain metadata.json and at least one .arrow file.
+          self.assertIn('metadata.json', names)
+          arrow_files = [n for n in names if n.endswith('.arrow')]
+          self.assertGreater(len(arrow_files), 0)
+
+          # Verify arrow files have ARROW1 magic bytes.
+          for name in arrow_files:
+            member = tf.extractfile(name)
+            self.assertIsNotNone(member)
+            data = member.read()
+            self.assertTrue(data[:6] == b'ARROW1', f'{name} missing ARROW1 header')
+      finally:
+        os.unlink(output_path)