TaskScheduler [3/9] Task and Sequence

base/task_scheduler/sequence_sort_key.cc

Index: base/task_scheduler/sequence_sort_key.cc
diff --git a/base/task_scheduler/sequence_sort_key.cc b/base/task_scheduler/sequence_sort_key.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5fe659bed7d1974ed4fe082fb3af56b87613c8fc
--- /dev/null
+++ b/base/task_scheduler/sequence_sort_key.cc
@@ -0,0 +1,36 @@
+// Copyright 2016 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 "base/task_scheduler/sequence_sort_key.h"
+
+namespace base {
+namespace internal {
+
+SequenceSortKey::SequenceSortKey(TaskPriority priority,
+                                 TimeTicks next_task_sequenced_time)
+    : priority(priority), next_task_sequenced_time(next_task_sequenced_time) {}
+
+bool SequenceSortKey::operator<(const SequenceSortKey& other) const {
+  // This SequenceSortKey is considered less important than |other| if it has a
+  // lower priority or if it has the same priority but its next task was posted
+  // later than |other|'s.
+  const int priority_diff =
+      static_cast<TaskPriorityUnderlyingType>(priority) -
+      static_cast<TaskPriorityUnderlyingType>(other.priority);
+  return priority_diff != 0

[danakj, 2016/03/15 23:16:32]

not a big fan of multiline ternary if statements.

if (priority_diff < 0) return true;
if (priority_diff > 0) return false;
return time > othertime;

^ Would be easier to read, and maybe you wouldn't even need explanatory
comments, up to you.

Or if you're concerned about # of ops..

if (priority_diff == 0)
  return time > othertime;
return priorify_diff < 0;

Idk if those compile to anything different but yeh.

[fdoray, 2016/03/16 19:11:43]

Done. I think the comment is still useful to explain why we use operator> to
implement an operator< (line 24).

+             ? priority_diff < 0
+             : next_task_sequenced_time > other.next_task_sequenced_time;
+}
+
+bool SequenceSortKey::operator>(const SequenceSortKey& other) const {
+  const int priority_diff =

[danakj, 2016/03/15 23:16:32]

Can this not be implemented in terms of operator<?

return other < *this;

You could inline that in the header too.

[fdoray, 2016/03/16 19:11:43]

Done.

+      static_cast<TaskPriorityUnderlyingType>(priority) -
+      static_cast<TaskPriorityUnderlyingType>(other.priority);
+  return priority_diff != 0
+             ? priority_diff > 0
+             : next_task_sequenced_time < other.next_task_sequenced_time;
+}
+
+}  // namespace internal
+}  // namespace base