feat(api): Added error_sampler option

sentry_sdk/client.py

@@ -456,10 +456,11 @@ def _should_sample_error(
         event,  # type: Event
     ):
         # type: (...) -> bool
-        not_in_sample_rate = (
-            self.options["sample_rate"] < 1.0
-            and random.random() >= self.options["sample_rate"]
-        )
+        try:
+            sample_rate = self.options["issues_sampler"](event)
+        except (KeyError, TypeError):
+            sample_rate = self.options["sample_rate"]
+        not_in_sample_rate = sample_rate < 1.0 and random.random() >= sample_rate
         if not_in_sample_rate:
             # because we will not sample this event, record a "lost event".
             if self.transport:

sentry_sdk/consts.py

@@ -261,6 +261,7 @@ def __init__(
         event_scrubber=None,  # type: Optional[sentry_sdk.scrubber.EventScrubber]
         max_value_length=DEFAULT_MAX_VALUE_LENGTH,  # type: int
         enable_backpressure_handling=True,  # type: bool
+        issues_sampler=None,  # type: Optional[Callable[[Event], Union[float, bool]]]
     ):
         # type: (...) -> None
         pass

tests/test_client.py

@@ -1196,3 +1196,44 @@ def test_debug_option(
         assert "something is wrong" in caplog.text
     else:
         assert "something is wrong" not in caplog.text
+
+
+@pytest.mark.parametrize(
+    ("sampler_function_mock", "sample_rate", "expected_events"),
+    (
+        # Baseline test with issues_sampler only, both floats and bools
+        (mock.MagicMock(return_value=1.0), None, 1),
+        (mock.MagicMock(return_value=0.0), None, 0),
+        (mock.MagicMock(return_value=True), None, 1),
+        (mock.MagicMock(return_value=False), None, 0),
+        # Baseline test with sample_rate only
+        (None, 0.0, 0),
+        (None, 1.0, 1),
+        # issues_sampler takes precedence over sample_rate
+        (mock.MagicMock(return_value=1.0), 0.0, 1),
+        (mock.MagicMock(return_value=0.0), 1.0, 0),
+    ),
+)
+def test_issues_sampler(
+    sentry_init, capture_events, sampler_function_mock, sample_rate, expected_events
+):
+    sentry_init(issues_sampler=sampler_function_mock, sample_rate=sample_rate)
+
+    events = capture_events()
+
+    try:
+        1 / 0
+    except ZeroDivisionError:
+        capture_exception()
+
+    assert len(events) == expected_events
+
+    try:
+        sampler_function_mock.assert_called_once()
+
+        # Ensure one argument (the event) was passed to the sampler function
+        assert len(sampler_function_mock.call_args[0]) == 1
+    except AttributeError:
+        # sampler_function_mock should be None in this case,
+        # but let's double-check to ensure the test is working correctly
+        assert sampler_function_mock is None