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..035e6ca53e74c53f43440a4d90cbe5943fcffdab
--- /dev/null
+++ b/base/task_scheduler/sequence_sort_key.cc
@@ -0,0 +1,34 @@
+// 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() : priority_(TaskPriority::BACKGROUND) {}
+
+SequenceSortKey::SequenceSortKey(TaskPriority priority,
+                                 TimeTicks next_task_post_time)
+    : priority_(priority), next_task_post_time_(next_task_post_time) {}
+
+bool SequenceSortKey::operator<(const SequenceSortKey& other) const {
+  if (static_cast<TaskPriorityUnderlyingType>(priority_) <
+      static_cast<TaskPriorityUnderlyingType>(other.priority_)) {
+    return true;
+  }
+  if (static_cast<TaskPriorityUnderlyingType>(priority_) >
+      static_cast<TaskPriorityUnderlyingType>(other.priority_)) {
+    return false;
+  }
+  return next_task_post_time_ > other.next_task_post_time_;

[gab, 2016/02/18 03:00:46]

How about:

--------------
// Sort by highest priority first, earliest post time second.
const int priority_diff = 
    static_cast<TaskPriorityUnderlyingType>(other.priority_) - 
    static_cast<TaskPriorityUnderlyingType>(priority_);
return priority_diff != 0
    ? priority_diff < 0
    : next_task_post_time_ > other.next_task_post_time_;
--------------

Less lines, less branches, less returns :-)

[fdoray, 2016/02/18 14:56:12]

Done. Note:  priority_diff > 0 instead of  priority_diff < 0.

[gab, 2016/02/18 20:22:34]

Ah oops, that's because I meant for priority_diff to be |priority_ -
other.priority_|.

i.e. in an operator< I prefer to compare with a < operator (except on time where
higher post time means lesser priority).

+}
+
+bool SequenceSortKey::operator==(const SequenceSortKey& other) const {
+  return priority_ == other.priority_ &&
+         next_task_post_time_ == other.next_task_post_time_;
+}
+
+}  // namespace internal
+}  // namespace base