Fix premature cleanup in provide. (#1490)

Co-authored-by: Joey Jurjens <joey@highbiza.nl>

src/django_components/perfutil/provide.py

@@ -93,12 +93,20 @@ provide_references: Dict[str, Set[str]] = defaultdict(set)
 # NOTE: We manually clean up the entries when components are garbage collected.
 component_provides: Dict[str, Dict[str, str]] = defaultdict(dict)
 
+# Track which {% provide %} blocks are currently active (rendering).
+# This prevents premature cache cleanup when components are garbage collected.
+active_provides: Set[str] = set()
+
 
 @contextmanager
 def managed_provide_cache(provide_id: str) -> Generator[None, None, None]:
+    # Mark this provide block as active
+    active_provides.add(provide_id)
     try:
         yield
     except Exception as e:
+        # Mark this provide block as no longer active
+        active_provides.discard(provide_id)
         # NOTE: In case of an error in within the `{% provide %}` block (e.g. when rendering a component),
         # we rely on the component finalizer to remove the references.
         # But we still want to call cleanup in case `{% provide %}` contained no components.
@@ -106,11 +114,17 @@ def managed_provide_cache(provide_id: str) -> Generator[None, None, None]:
         # Forward the error
         raise e from None
 
+    # Mark this provide block as no longer active
+    active_provides.discard(provide_id)
     # Cleanup on success
     _cache_cleanup(provide_id)
 
 
 def _cache_cleanup(provide_id: str) -> None:
+    # Don't cleanup if the provide block is still active.
+    if provide_id in active_provides:
+        return
+
     # Remove provided data from the cache, IF there are no more references to it.
     # A `{% provide %}` will have no reference if:
     # - It contains no components in its body

tests/test_templatetags_provide.py

@@ -1297,3 +1297,46 @@ class TestProvideCache:
             Root.render()
 
         _assert_clear_cache()
+
+    @djc_test(parametrize=PARAMETRIZE_CONTEXT_BEHAVIOR)
+    def test_provide_cache_not_cleaned_while_active(self, components_settings):
+        @register("injectee31")
+        class Injectee(Component):
+            template: types.django_html = """
+                <div>{{ value }}</div>
+            """
+
+            def get_template_data(self, args, kwargs, slots, context):
+                data = self.inject("my_provide")
+                return {"value": data.value}
+
+        @register("root")
+        class Root(Component):
+            template: types.django_html = """
+                <div>{{ content|safe }}</div>
+            """
+
+            def get_template_data(self, args, kwargs, slots, context):
+                # Nested synchronous rendering triggers GC between components.
+                nested_template = Template(
+                    """
+                    {% load component_tags %}
+                    {% for i in "xxxxxxxxxx" %}
+                        {% provide "my_provide" value="hello" %}
+                            {% component "injectee31" %}{% endcomponent %}
+                            {% component "injectee31" %}{% endcomponent %}
+                            {% component "injectee31" %}{% endcomponent %}
+                        {% endprovide %}
+                    {% endfor %}
+                """
+                )
+                content = nested_template.render(Context({}))
+                return {"content": content}
+
+        _assert_clear_cache()
+
+        rendered = Root.render()
+
+        # 10 iterations * 3 components = 30 occurrences
+        assert rendered.count(">hello</div>") == 30
+        _assert_clear_cache()