Global Resource Coordinator: Basic service internals

services/resource_coordinator/public/cpp/coordination_unit_id.cc

Index: services/resource_coordinator/public/cpp/coordination_unit_id.cc
diff --git a/services/resource_coordinator/public/cpp/coordination_unit_id.cc b/services/resource_coordinator/public/cpp/coordination_unit_id.cc
new file mode 100644
index 0000000000000000000000000000000000000000..52d4827622384ddb6bda993dd0967b312fc78e6a
--- /dev/null
+++ b/services/resource_coordinator/public/cpp/coordination_unit_id.cc
@@ -0,0 +1,21 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "services/resource_coordinator/public/cpp/coordination_unit_id.h"
+
+#include "base/hash.h"
+
+namespace resource_coordinator {
+
+namespace {}  // namespace

[Primiano Tucci (use gerrit), 2017/04/06 18:09:47]

I guess this is a leftover?

[oystein (OOO til 10th of July), 2017/04/10 20:03:00]

Yep; done.

+
+CoordinationUnitID::CoordinationUnitID() = default;

[Primiano Tucci (use gerrit), 2017/04/06 18:09:46]

my ignorance: will the =Default ctor zero initialize the pods here?

[oystein (OOO til 10th of July), 2017/04/10 20:03:00]

Nope; holdover from when id was an std::string.

+
+CoordinationUnitID::CoordinationUnitID(const CoordinationUnitType& type,
+                                       const std::string& new_id)
+    : type(type) {
+  id = base::Hash(new_id);

[Primiano Tucci (use gerrit), 2017/04/06 18:09:46]

I got very bitten by base::Hash in the past with memory-infra. It doesn't play
very well with strings that are identical % suffix.

See
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/-rXNiOoIU4A/LI4tn...
for my horror story.
If this case is similar nad performance isn't critical here, I suggest using
base::Sha1

[oystein (OOO til 10th of July), 2017/04/10 20:03:00]

Ah good to know. I switched to Murmur2. skyostil@ might have more
performance-critical use-cases for CoordinationUnitID in the future so Murmur2
might be faster? We can reevaluate this though.

+}
+
+}  // resource_coordinator