Add fd event support to EventTaskRunner

This change allows applications to perform
general I/O completion handling as part of the
Run() loop, rather than just timeout completion.

Change-Id: Idce97a33f7a35348ac5a7d226491f9907edc3405
Reviewed-on: https://weave-review.googlesource.com/1447
Reviewed-by: Vitaly Buka <vitalybuka@google.com>

examples/provider/event_deleter.h

diff --git a/examples/provider/event_deleter.h b/examples/provider/event_deleter.h
new file mode 100644
index 0000000..078c326
--- /dev/null
+++ b/examples/provider/event_deleter.h
@@ -0,0 +1,37 @@
+// Copyright 2015 The Weave Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef LIBWEAVE_EXAMPLES_PROVIDER_EVENT_DELETER_H
+#define LIBWEAVE_EXAMPLES_PROVIDER_EVENT_DELETER_H
+
+#include <memory>
+
+#include <third_party/include/event2/event.h>
+#include <third_party/include/event2/event_struct.h>
+#include <third_party/include/event2/http.h>
+
+namespace weave {
+namespace examples {
+
+// Defines overloaded deletion methods for various event_ objects
+// so we can use one unique_ptr definition for all of them
+class EventDeleter {
+ public:
+  void operator()(evhttp_uri* http_uri) { evhttp_uri_free(http_uri); }
+  void operator()(evhttp_connection* conn) { evhttp_connection_free(conn); }
+  void operator()(evhttp_request* req) { evhttp_request_free(req); }
+  void operator()(event_base* base) { event_base_free(base); }
+  void operator()(event* ev) {
+    event_del(ev);
+    event_free(ev);
+  }
+};
+
+template <typename T>
+using EventPtr = std::unique_ptr<T, EventDeleter>;
+
+}  // namespace examples
+}  // namespace weave
+
+#endif  // LIBWEAVE_EXAMPLES_PROVIDER_EVENT_DELETER_H