[PM] Create GraphOwned helper class.
This provides functionality that allows external clients to tie lifetimes
of their objects directly to that of a graph instance. Can be used in a
way similar to PerformanceManager::RegisterObserver, but more generically.
This will ease the transition of legacy observers to the new public
interfaces.
BUG=910288
Change-Id: I22cd06ba1a6b8a19c4bd76b05c0523c2f76ee421
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1665548
Commit-Queue: Chris Hamilton <[email protected]>
Reviewed-by: Sigurður Ásgeirsson <[email protected]>
Cr-Commit-Position: refs/heads/master@{#673114}
diff --git a/chrome/browser/performance_manager/public/graph/graph.h b/chrome/browser/performance_manager/public/graph/graph.h
index 5bceb6c0..0cc76500 100644
--- a/chrome/browser/performance_manager/public/graph/graph.h
+++ b/chrome/browser/performance_manager/public/graph/graph.h
@@ -6,12 +6,15 @@
#define CHROME_BROWSER_PERFORMANCE_MANAGER_PUBLIC_GRAPH_GRAPH_H_
#include <cstdint>
+#include <memory>
#include "base/macros.h"
+#include "base/memory/ptr_util.h"
namespace performance_manager {
class GraphObserver;
+class GraphOwned;
class FrameNodeObserver;
class PageNodeObserver;
class ProcessNodeObserver;
@@ -42,6 +45,21 @@
virtual void RemoveProcessNodeObserver(ProcessNodeObserver* observer) = 0;
virtual void RemoveSystemNodeObserver(SystemNodeObserver* observer) = 0;
+ // For convenience, allows you to pass ownership of an object to the graph.
+ // Useful for attaching observers that will live with the graph until it dies.
+ // If you can name the object you can also take it back via "TakeFromGraph".
+ virtual void PassToGraph(std::unique_ptr<GraphOwned> graph_owned) = 0;
+ virtual std::unique_ptr<GraphOwned> TakeFromGraph(
+ GraphOwned* graph_owned) = 0;
+
+ // A TakeFromGraph helper that casts to a derived type. It is up to the caller
+ // to ensure that the cast is safe.
+ template <typename DerivedType>
+ std::unique_ptr<DerivedType> TakeFromGraphAs(GraphOwned* graph_owned) {
+ return base::WrapUnique(
+ static_cast<DerivedType*>(TakeFromGraph(graph_owned).release()));
+ }
+
// The following functions are implementation detail and should not need to be
// used by external clients. They provide the ability to safely downcast to
// the underlying implementation.
@@ -59,18 +77,48 @@
virtual ~GraphObserver();
// Called before the |graph| associated with this observer disappears. This
- // allows the observer to do any necessary cleanup work. Note that the graph
- // is in its destructor while this is being called, so the observer should
- // refrain from uselessly modifying the graph. This is intended to be used to
- // facilitate lifetime management of observers.
- // TODO(chrisha): Make this run before the constructor!
+ // allows the observer to do any necessary cleanup work. Note that the
+ // observer should remove itself from observing the graph using this
+ // callback.
+ // TODO(chrisha): Make this run before the destructor!
// crbug.com/966840
- virtual void OnBeforeGraphDestroyed(const Graph* graph) = 0;
+ virtual void OnBeforeGraphDestroyed(Graph* graph) = 0;
private:
DISALLOW_COPY_AND_ASSIGN(GraphObserver);
};
+// Helper class for passing ownership of objects to a graph.
+class GraphOwned {
+ public:
+ GraphOwned();
+ virtual ~GraphOwned();
+
+ // Called when the object is passed into the graph.
+ virtual void OnPassedToGraph(Graph* graph) = 0;
+
+ // Called when the object is removed from the graph, either via an explicit
+ // call to Graph::TakeFromGraph, or prior to the Graph being destroyed.
+ virtual void OnTakenFromGraph(Graph* graph) = 0;
+
+ private:
+ DISALLOW_COPY_AND_ASSIGN(GraphOwned);
+};
+
+// A default implementation of GraphOwned.
+class GraphOwnedDefaultImpl : public GraphOwned {
+ public:
+ GraphOwnedDefaultImpl();
+ ~GraphOwnedDefaultImpl() override;
+
+ // GraphOwned implementation:
+ void OnPassedToGraph(Graph* graph) override {}
+ void OnTakenFromGraph(Graph* graph) override {}
+
+ private:
+ DISALLOW_COPY_AND_ASSIGN(GraphOwnedDefaultImpl);
+};
+
} // namespace performance_manager
#endif // CHROME_BROWSER_PERFORMANCE_MANAGER_PUBLIC_GRAPH_GRAPH_H_
