From e9dedb13ab767bffcf942080d8963e23c4657519 Mon Sep 17 00:00:00 2001
From: Steve Dower <steve.dower@python.org>
Date: Wed, 4 Jun 2025 16:45:42 +0100
Subject: [PATCH 1/2] Allow calling mark() when not tracing

---
 src/etwtrace/__init__.py | 30 +++++++++++++++++++++---------
 tests/test_etw.py        | 12 ++++++++++++
 2 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/src/etwtrace/__init__.py b/src/etwtrace/__init__.py
index 886b2d4..9e4171b 100644
--- a/src/etwtrace/__init__.py
+++ b/src/etwtrace/__init__.py
@@ -171,22 +171,34 @@ def enable_if(enable_var, type_var):
 
 def mark(name):
     """Emits a mark event with the provided text."""
-    if not _tracer:
-        raise RuntimeError("unable to mark when global tracer is not enabled")
-    _tracer.mark(name)
+    if _tracer:
+        _tracer.mark(name)
+    else:
+        import warnings
+        warnings.warn("Unable to mark when global tracer is not enabled", RuntimeWarning)
+
+
+class _NullRange:
+    def __enter__(self): return self
+    def __exit__(self, *exc_info): pass
 
 
 def mark_range(name):
     """Context manager to emit start/stop mark events with the provided text."""
-    if not _tracer:
-        raise RuntimeError("unable to mark when global tracer is not enabled")
-    return _tracer.mark_range(name)
+    if _tracer:
+        return _tracer.mark_range(name)
+    else:
+        import warnings
+        warnings.warn("Unable to mark when global tracer is not enabled", RuntimeWarning)
+        return _NullRange()
 
 
 def _mark_stack(mark):
-    if not _tracer:
-        raise RuntimeError("unable to mark when global tracer is not enabled")
-    return _tracer._mark_stack(mark)
+    if _tracer:
+        return _tracer._mark_stack(mark)
+    else:
+        import warnings
+        warnings.warn("Unable to mark when global tracer is not enabled", RuntimeWarning)
 
 
 _TEMP_PROFILE = None
diff --git a/tests/test_etw.py b/tests/test_etw.py
index a72e83e..4d52292 100644
--- a/tests/test_etw.py
+++ b/tests/test_etw.py
@@ -234,6 +234,18 @@ def test_but_do_we_instrument():
     )
 
 
+def test_but_do_we_warn_on_mark():
+    with pytest.warns(RuntimeWarning):
+        etwtrace.mark("Test mark without tracing")
+
+    with pytest.warns(RuntimeWarning):
+        with etwtrace.mark_range("Test mark without tracing"):
+            pass
+
+    with pytest.warns(RuntimeWarning):
+        etwtrace._mark_stack("Test mark without tracing")
+
+
 def test_basic(trace_events):
     funcs = set()
     with trace_events("basic.py", providers=['Python']) as etl:

From 400a1f33d6aa025e65704509b99300c7bb002179 Mon Sep 17 00:00:00 2001
From: Steve Dower <steve.dower@python.org>
Date: Wed, 4 Jun 2025 16:47:13 +0100
Subject: [PATCH 2/2] Add is_active function

---
 src/etwtrace/__init__.py | 5 +++++
 tests/test_etw.py        | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/src/etwtrace/__init__.py b/src/etwtrace/__init__.py
index 9e4171b..7f0ad5b 100644
--- a/src/etwtrace/__init__.py
+++ b/src/etwtrace/__init__.py
@@ -169,6 +169,11 @@ def enable_if(enable_var, type_var):
     tracer.enable()
 
 
+def is_active():
+    """Returns True if tracing is active."""
+    return bool(_tracer)
+
+
 def mark(name):
     """Emits a mark event with the provided text."""
     if _tracer:
diff --git a/tests/test_etw.py b/tests/test_etw.py
index 4d52292..3ed3a33 100644
--- a/tests/test_etw.py
+++ b/tests/test_etw.py
@@ -234,6 +234,10 @@ def test_but_do_we_instrument():
     )
 
 
+def test_but_are_we_inactive():
+    assert etwtrace.is_active() is False
+
+
 def test_but_do_we_warn_on_mark():
     with pytest.warns(RuntimeWarning):
         etwtrace.mark("Test mark without tracing")