Introduce MultiPriorityQueue

ACL and L2cap needs to prioritize some link/channels in some cases.  A
traditional priority queue requires predefined comparison, which can be
hard for our use case (PacketBuilder).  Instead, we specify the priority
value when we push to a queue.

Test: bluetooth_test_gd
Tag: #gd-refactor
Bug: 141555841
Change-Id: I33414b4bf81e9f63c88d8627376b565f5c5bb6de

diff --git a/gd/common/Android.bp b/gd/common/Android.bp
index 5c66da4..c176992 100644 (file)
--- a/gd/common/Android.bp
+++ b/gd/common/Android.bp
@@ -17,6 +17,7 @@ filegroup {
         "init_flags_test.cc",
         "list_map_test.cc",
         "lru_cache_test.cc",
+        "multi_priority_queue_test.cc",
         "numbers_test.cc",
         "strings_test.cc",
     ],

diff --git a/gd/common/multi_priority_queue.h b/gd/common/multi_priority_queue.h
new file mode 100644 (file)
index 0000000..dd4785b
--- /dev/null
+++ b/gd/common/multi_priority_queue.h
@@ -0,0 +1,69 @@
+/******************************************************************************
+ *
+ *  Copyright 2021 The Android Open Source Project
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at:
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ ******************************************************************************/
+
+#pragma once
+
+#include <array>
+#include <queue>
+
+namespace bluetooth {
+namespace common {
+
+/**
+ * A queue implementation which supports items with multiple priorities.
+ * Items with greater priority value will be dequeued first.
+ * When Enqueuing, the user can specify the priority (0 by default).
+ * This can be used by ACL or L2CAP lower queue end sender to prioritize some link or channel, used by A2DP.
+ */
+template <typename T, int NUM_PRIORITY_LEVELS = 2>
+class MultiPriorityQueue {
+  static_assert(NUM_PRIORITY_LEVELS > 1);
+
+ public:
+  // Get the front item with the highest priority.  Queue must be non-empty.
+  T& front() {
+    return queues_[next_to_dequeue_.top()].front();
+  }
+
+  [[nodiscard]] bool empty() const {
+    return next_to_dequeue_.empty();
+  }
+
+  [[nodiscard]] size_t size() const {
+    return next_to_dequeue_.size();
+  }
+
+  // Push the item with specified priority
+  void push(const T& t, int priority = 0) {
+    queues_[priority].push(t);
+    next_to_dequeue_.push(priority);
+  }
+
+  // Pop the item in the front
+  void pop() {
+    queues_[next_to_dequeue_.top()].pop();
+    next_to_dequeue_.pop();
+  }
+
+ private:
+  std::array<std::queue<T>, NUM_PRIORITY_LEVELS> queues_;
+  std::priority_queue<int> next_to_dequeue_;
+};
+
+}  // namespace common
+}  // namespace bluetooth

diff --git a/gd/common/multi_priority_queue_test.cc b/gd/common/multi_priority_queue_test.cc
new file mode 100644 (file)
index 0000000..6677525
--- /dev/null
+++ b/gd/common/multi_priority_queue_test.cc
@@ -0,0 +1,63 @@
+/******************************************************************************
+ *
+ *  Copyright 2021 The Android Open Source Project
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at:
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ ******************************************************************************/
+
+#include <gtest/gtest.h>
+
+#include "common/multi_priority_queue.h"
+
+namespace bluetooth {
+namespace common {
+
+TEST(MultiPriorityQueueTest, without_high_priority_item) {
+  common::MultiPriorityQueue<int, 2> q;
+  EXPECT_TRUE(q.empty());
+  q.push(0);
+  q.push(1, 0);
+  q.push(2);
+  EXPECT_EQ(q.size(), 3);
+  for (int i = 0; i < 3; i++) {
+    EXPECT_EQ(q.front(), i);
+    q.pop();
+  }
+  EXPECT_TRUE(q.empty());
+}
+
+TEST(MultiPriorityQueueTest, with_high_priority_item) {
+  common::MultiPriorityQueue<int, 2> q;
+  q.push(1);
+  q.push(2);
+  q.push(0, 1);
+  for (int i = 0; i < 3; i++) {
+    EXPECT_EQ(q.front(), i);
+    q.pop();
+  }
+}
+
+TEST(MultiPriorityQueueTest, with_multiple_priority_item) {
+  common::MultiPriorityQueue<int, 3> q;
+  q.push(1, 1);
+  q.push(0, 2);
+  q.push(2, 0);
+  for (int i = 0; i < 3; i++) {
+    EXPECT_EQ(q.front(), i);
+    q.pop();
+  }
+}
+
+}  // namespace common
+}  // namespace bluetooth