fix(clickhouse): Don't eat the generator data (#4669)

Currently, the Clickhouse integration consumes any data passed as a
generator when reading it for insertion as `db_params`. Instead, since
generators cannot be cloned, we need to wrap the generator to add the
params as we iterate over it.

Fixes #4657

<!-- Describe your PR here -->

---

Thank you for contributing to `sentry-python`! Please add tests to
validate your changes, and lint your code using `tox -e linters`.

Running the test suite on your PR might require maintainer approval.

Author: szokeasaurusrex

sentry_sdk/integrations/clickhouse_driver.py

@@ -11,7 +11,8 @@
 # without introducing a hard dependency on `typing_extensions`
 # from: https://stackoverflow.com/a/71944042/300572
 if TYPE_CHECKING:
-    from typing import ParamSpec, Callable
+    from collections.abc import Iterator
+    from typing import Any, ParamSpec, Callable
 else:
     # Fake ParamSpec
     class ParamSpec:
@@ -139,7 +140,24 @@ def _inner_send_data(  # type: ignore[no-untyped-def] # clickhouse-driver does n
 
             if should_send_default_pii():
                 db_params = span._data.get("db.params", [])
-                db_params.extend(data)
+
+                if isinstance(data, (list, tuple)):
+                    db_params.extend(data)
+
+                else:  # data is a generic iterator
+                    orig_data = data
+
+                    # Wrap the generator to add items to db.params as they are yielded.
+                    # This allows us to send the params to Sentry without needing to allocate
+                    # memory for the entire generator at once.
+                    def wrapped_generator() -> "Iterator[Any]":
+                        for item in orig_data:
+                            db_params.append(item)
+                            yield item
+
+                    # Replace the original iterator with the wrapped one.
+                    data = wrapped_generator()
+
                 span.set_data("db.params", db_params)
 
         return original_send_data(

tests/integrations/clickhouse_driver/test_clickhouse_driver.py

@@ -342,6 +342,38 @@ def test_clickhouse_client_spans(
     assert event["spans"] == expected_spans
 
 
+def test_clickhouse_spans_with_generator(sentry_init, capture_events):
+    sentry_init(
+        integrations=[ClickhouseDriverIntegration()],
+        send_default_pii=True,
+        traces_sample_rate=1.0,
+    )
+    events = capture_events()
+
+    # Use a generator to test that the integration obtains values from the generator,
+    # without consuming the generator.
+    values = ({"x": i} for i in range(3))
+
+    with start_transaction(name="test_clickhouse_transaction"):
+        client = Client("localhost")
+        client.execute("DROP TABLE IF EXISTS test")
+        client.execute("CREATE TABLE test (x Int32) ENGINE = Memory")
+        client.execute("INSERT INTO test (x) VALUES", values)
+        res = client.execute("SELECT x FROM test")
+
+    # Verify that the integration did not consume the generator
+    assert res == [(0,), (1,), (2,)]
+
+    (event,) = events
+    spans = event["spans"]
+
+    [span] = [
+        span for span in spans if span["description"] == "INSERT INTO test (x) VALUES"
+    ]
+
+    assert span["data"]["db.params"] == [{"x": 0}, {"x": 1}, {"x": 2}]
+
+
 def test_clickhouse_client_spans_with_pii(
     sentry_init, capture_events, capture_envelopes
 ) -> None: