Implement HTTP/2 priority tree structure.

net/spdy/spdy_priority_tree_test.cc

+// Copyright (c) 2014 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 "net/spdy/spdy_priority_tree.h"
+
+#include "base/basictypes.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+namespace test {
+
+template <typename NodeId>
+class SpdyPriorityTreePeer {
+ public:
+  explicit SpdyPriorityTreePeer(SpdyPriorityTree<NodeId>* tree) : tree_(tree) {}
+
+  void PropagateNodeState(NodeId node) {
+    tree_->PropagateNodeState(node);
+  }
+
+ private:
+  SpdyPriorityTree<NodeId>* tree_;
+};
+
+TEST(SpdyPriorityTreeTest, AddAndRemoveNodes) {
+  SpdyPriorityTree<uint32> tree;
+  EXPECT_EQ(1, tree.num_nodes());
+  EXPECT_TRUE(tree.NodeExists(0));
+  EXPECT_FALSE(tree.NodeExists(1));
+
+  EXPECT_TRUE(tree.AddNode(1, 0, 100, false));
+  EXPECT_EQ(2, tree.num_nodes());
+  ASSERT_TRUE(tree.NodeExists(1));
+  EXPECT_EQ(100, tree.GetWeight(1));
+  EXPECT_FALSE(tree.NodeExists(5));
+
+  EXPECT_TRUE(tree.AddNode(5, 0, 50, false));
+  // Should not be able to add a node with an id that already exists.
+  EXPECT_FALSE(tree.AddNode(5, 1, 50, false));
+  EXPECT_EQ(3, tree.num_nodes());
+  EXPECT_TRUE(tree.NodeExists(1));
+  ASSERT_TRUE(tree.NodeExists(5));
+  EXPECT_EQ(50, tree.GetWeight(5));
+  EXPECT_FALSE(tree.NodeExists(13));
+
+  EXPECT_TRUE(tree.AddNode(13, 5, 130, true));
+  EXPECT_EQ(4, tree.num_nodes());
+  EXPECT_TRUE(tree.NodeExists(1));
+  EXPECT_TRUE(tree.NodeExists(5));
+  ASSERT_TRUE(tree.NodeExists(13));
+  EXPECT_EQ(130, tree.GetWeight(13));
+  EXPECT_EQ(5u, tree.GetParent(13));
+
+  EXPECT_TRUE(tree.RemoveNode(5));
+  // Cannot remove a node that has already been removed.
+  EXPECT_FALSE(tree.RemoveNode(5));
+  EXPECT_EQ(3, tree.num_nodes());
+  EXPECT_TRUE(tree.NodeExists(1));
+  EXPECT_FALSE(tree.NodeExists(5));
+  EXPECT_TRUE(tree.NodeExists(13));
+  EXPECT_EQ(0u, tree.GetParent(13));
+
+  // The parent node 19 doesn't exist, so this should fail:
+  EXPECT_FALSE(tree.AddNode(7, 19, 70, false));
+  // This should succeed, creating node 7:
+  EXPECT_TRUE(tree.AddNode(7, 13, 70, false));
+  // Now node 7 already exists, so this should fail:
+  EXPECT_FALSE(tree.AddNode(7, 1, 70, false));
+  // Try adding a second child to node 13:
+  EXPECT_TRUE(tree.AddNode(17, 13, 170, false));
+
+  ASSERT_TRUE(tree.ValidateInvariantsForTests());
+}
+
+TEST(SpdyPriorityTreeTest, SetParent) {
+  SpdyPriorityTree<uint32> tree;
+  tree.AddNode(1, 0, 100, false);
+  tree.AddNode(2, 1, 20, false);
+  tree.AddNode(3, 2, 30, false);
+  tree.AddNode(5, 3, 50, false);
+  tree.AddNode(7, 5, 70, false);
+  tree.AddNode(9, 7, 90, false);
+  tree.AddNode(11, 0, 200, false);
+  tree.AddNode(13, 11, 130, false);
+  // We can't set the parent of a nonexistent node, or set the parent of an
+  // existing node to a nonexistent node.
+  EXPECT_FALSE(tree.SetParent(99, 13, false));
+  EXPECT_FALSE(tree.SetParent(5, 99, false));
+  // We should be able to add multiple children to nodes.
+  EXPECT_TRUE(tree.SetParent(13, 7, false));
+  EXPECT_TRUE(tree.SetParent(3, 11, false));
+  // We should adjust the tree if a new dependency would create a cycle.
+  EXPECT_TRUE(tree.SetParent(11, 13, false));
+  EXPECT_TRUE(tree.SetParent(1, 9, false));
+  EXPECT_TRUE(tree.SetParent(3, 9, false));
+  // Test dependency changes.
+  EXPECT_TRUE(tree.HasChild(5, 7));
+  EXPECT_TRUE(tree.SetParent(7, 13, false));
+  EXPECT_EQ(13u, tree.GetParent(7));
+  EXPECT_TRUE(tree.HasChild(13, 7));
+
+  EXPECT_TRUE(tree.SetParent(1, 9, false));
+  EXPECT_EQ(9u, tree.GetParent(1));
+  EXPECT_TRUE(tree.HasChild(9, 1));
+  // Setting the parent of a node to its same parent should be a no-op.
+  EXPECT_EQ(1u, tree.GetParent(2));
+  EXPECT_TRUE(tree.HasChild(1, 2));
+  EXPECT_TRUE(tree.SetParent(2, 1, true));
+  EXPECT_EQ(1u, tree.GetParent(2));
+  EXPECT_TRUE(tree.HasChild(1, 2));
+
+  ASSERT_TRUE(tree.ValidateInvariantsForTests());
+}
+
+TEST(SpdyPriorityTreeTest, BlockAndUnblock) {
+  /* Create the tree.
+
+           0
+          /|\
+         1 2 3
+        /| |  \
+       4 5 6   7
+      /| |\ \  |\
+     8 91011121314
+    / \
+   15 16
+
+  */
+  SpdyPriorityTree<uint32> tree;
+  SpdyPriorityTreePeer<uint32> tree_peer(&tree);
+  tree.AddNode(1, 0, 100, false);
+  tree.AddNode(2, 0, 100, false);
+  tree.AddNode(3, 0, 100, false);
+  tree.AddNode(4, 1, 100, false);
+  tree.AddNode(5, 1, 100, false);
+  tree.AddNode(8, 4, 100, false);
+  tree.AddNode(9, 4, 100, false);
+  tree.AddNode(10, 5, 100, false);
+  tree.AddNode(11, 5, 100, false);
+  tree.AddNode(15, 8, 100, false);
+  tree.AddNode(16, 8, 100, false);
+  tree.AddNode(12, 2, 100, false);
+  tree.AddNode(6, 2, 100, true);
+  tree.AddNode(7, 0, 100, false);
+  tree.AddNode(13, 7, 100, true);
+  tree.AddNode(14, 7, 100, false);
+  tree.SetParent(7, 3, false);
+  EXPECT_EQ(0u, tree.GetParent(1));
+  EXPECT_EQ(0u, tree.GetParent(2));
+  EXPECT_EQ(0u, tree.GetParent(3));
+  EXPECT_EQ(1u, tree.GetParent(4));
+  EXPECT_EQ(1u, tree.GetParent(5));
+  EXPECT_EQ(2u, tree.GetParent(6));
+  EXPECT_EQ(3u, tree.GetParent(7));
+  EXPECT_EQ(4u, tree.GetParent(8));
+  EXPECT_EQ(4u, tree.GetParent(9));
+  EXPECT_EQ(5u, tree.GetParent(10));
+  EXPECT_EQ(5u, tree.GetParent(11));
+  EXPECT_EQ(6u, tree.GetParent(12));
+  EXPECT_EQ(7u, tree.GetParent(13));
+  EXPECT_EQ(7u, tree.GetParent(14));
+  EXPECT_EQ(8u, tree.GetParent(15));
+  EXPECT_EQ(8u, tree.GetParent(16));
+  ASSERT_TRUE(tree.ValidateInvariantsForTests());
+
+  EXPECT_EQ(tree.FindNode(0)->total_child_weights,
+            tree.FindNode(1)->weight +
+            tree.FindNode(2)->weight +
+            tree.FindNode(3)->weight);
+  EXPECT_EQ(tree.FindNode(3)->total_child_weights,
+            tree.FindNode(7)->weight);
+  EXPECT_EQ(tree.FindNode(7)->total_child_weights,
+            tree.FindNode(13)->weight + tree.FindNode(14)->weight);
+  EXPECT_EQ(tree.FindNode(13)->total_child_weights, 0);
+  EXPECT_EQ(tree.FindNode(14)->total_child_weights, 0);
+
+  // Set all nodes ready to write.
+  EXPECT_TRUE(tree.SetReady(1, true));
+  EXPECT_TRUE(tree.SetReady(2, true));
+  EXPECT_TRUE(tree.SetReady(3, true));
+  EXPECT_TRUE(tree.SetReady(4, true));
+  EXPECT_TRUE(tree.SetReady(5, true));
+  EXPECT_TRUE(tree.SetReady(6, true));
+  EXPECT_TRUE(tree.SetReady(7, true));
+  EXPECT_TRUE(tree.SetReady(8, true));
+  EXPECT_TRUE(tree.SetReady(9, true));
+  EXPECT_TRUE(tree.SetReady(10, true));
+  EXPECT_TRUE(tree.SetReady(11, true));
+  EXPECT_TRUE(tree.SetReady(12, true));
+  EXPECT_TRUE(tree.SetReady(13, true));
+  EXPECT_TRUE(tree.SetReady(14, true));
+  EXPECT_TRUE(tree.SetReady(15, true));
+  EXPECT_TRUE(tree.SetReady(16, true));
+
+  // Number of readable child weights should not change because
+  // 7 has unblocked children.
+  tree.SetBlocked(7, true);
+  tree_peer.PropagateNodeState(kRootNodeId);
+  EXPECT_EQ(tree.FindNode(3)->total_child_weights,
+            tree.FindNode(3)->total_writeable_child_weights);
+
+  // Readable children for 7 should decrement.
+  // Number of readable child weights for 3 still should not change.
+  tree.SetBlocked(13, true);
+  tree_peer.PropagateNodeState(kRootNodeId);
+  EXPECT_EQ(tree.FindNode(3)->total_child_weights,
+            tree.FindNode(3)->total_writeable_child_weights);
+  EXPECT_EQ(tree.FindNode(14)->weight,
+            tree.FindNode(7)->total_writeable_child_weights);
+
+  // Once 14 becomes blocked, readable children for 7 and 3 should both be
+  // decremented. Total readable weights at the root should still be the same
+  // because 3 is still writeable.
+  tree.SetBlocked(14, true);
+  tree_peer.PropagateNodeState(kRootNodeId);
+  EXPECT_EQ(0, tree.FindNode(3)->total_writeable_child_weights);
+  EXPECT_EQ(0, tree.FindNode(7)->total_writeable_child_weights);
+  EXPECT_EQ(tree.FindNode(0)->total_child_weights,
+            tree.FindNode(1)->weight +
+            tree.FindNode(2)->weight +
+            tree.FindNode(3)->weight);
+
+  // And now the root should be decremented as well.
+  tree.SetBlocked(3, true);
+  tree_peer.PropagateNodeState(kRootNodeId);
+  EXPECT_EQ(tree.FindNode(1)->weight + tree.FindNode(2)->weight,
+            tree.FindNode(0)->total_writeable_child_weights);
+
+  // Unblocking 7 should propagate all the way up to the root.
+  tree.SetBlocked(7, false);
+  tree_peer.PropagateNodeState(kRootNodeId);
+  EXPECT_EQ(tree.FindNode(0)->total_writeable_child_weights,
+            tree.FindNode(1)->weight +
+            tree.FindNode(2)->weight +
+            tree.FindNode(3)->weight);
+  EXPECT_EQ(tree.FindNode(3)->total_writeable_child_weights,
+            tree.FindNode(7)->weight);
+  EXPECT_EQ(0, tree.FindNode(7)->total_writeable_child_weights);
+
+  // Ditto for reblocking 7.
+  tree.SetBlocked(7, true);
+  tree_peer.PropagateNodeState(kRootNodeId);
+  EXPECT_EQ(tree.FindNode(0)->total_writeable_child_weights,
+            tree.FindNode(1)->weight + tree.FindNode(2)->weight);
+  EXPECT_EQ(0, tree.FindNode(3)->total_writeable_child_weights);
+  EXPECT_EQ(0, tree.FindNode(7)->total_writeable_child_weights);
+  ASSERT_TRUE(tree.ValidateInvariantsForTests());
+}
+
+TEST(SpdyPriorityTreeTest, GetPriorityList) {
+  typedef uint32 SpdyStreamId;
+  typedef std::pair<SpdyStreamId, float> PriorityNode;
+  typedef std::vector<PriorityNode> PriorityList;
+
+  PriorityList expected_list;
+  PriorityList priority_list;
+
+  /* Create the tree.
+
+           0
+          /|\
+         1 2 3
+        /| |\
+       4 5 6 7
+      /
+     8
+
+  */
+  SpdyPriorityTree<uint32> tree;
+  tree.AddNode(1, 0, 10, false);
+  tree.AddNode(2, 0, 20, false);
+  tree.AddNode(3, 0, 30, false);
+  tree.AddNode(4, 1, 10, false);
+  tree.AddNode(5, 1, 90, false);
+  tree.AddNode(6, 2, 10, false);
+  tree.AddNode(7, 2, 10, false);
+  tree.AddNode(8, 4, 256, false);
+
+  // Set all nodes ready to write.
+  EXPECT_TRUE(tree.SetReady(1, true));
+  EXPECT_TRUE(tree.SetReady(2, true));
+  EXPECT_TRUE(tree.SetReady(3, true));
+  EXPECT_TRUE(tree.SetReady(4, true));
+  EXPECT_TRUE(tree.SetReady(5, true));
+  EXPECT_TRUE(tree.SetReady(6, true));
+  EXPECT_TRUE(tree.SetReady(7, true));
+  EXPECT_TRUE(tree.SetReady(8, true));
+
+  expected_list.push_back(PriorityNode(3, 1.0/2.0));
+  expected_list.push_back(PriorityNode(2, 1.0/3.0));
+  expected_list.push_back(PriorityNode(1, 1.0/6.0));
+  priority_list = tree.GetPriorityList();
+  EXPECT_EQ(expected_list, priority_list);
+
+  // Check that the list updates as expected when a node gets blocked.
+  EXPECT_TRUE(tree.SetReady(1, false));
+  expected_list.clear();
+  expected_list.push_back(PriorityNode(3, 1.0/2.0));
+  expected_list.push_back(PriorityNode(2, 1.0/3.0));
+  expected_list.push_back(PriorityNode(5, 0.9*1.0/6.0));
+  expected_list.push_back(PriorityNode(4, 0.1*1.0/6.0));
+  priority_list = tree.GetPriorityList();
+  EXPECT_EQ(expected_list, priority_list);
+
+  // Block multiple levels of nodes.
+  EXPECT_TRUE(tree.SetReady(4, false));
+  EXPECT_TRUE(tree.SetReady(5, false));
+  expected_list.clear();
+  expected_list.push_back(PriorityNode(3, 1.0/2.0));
+  expected_list.push_back(PriorityNode(2, 1.0/3.0));
+  expected_list.push_back(PriorityNode(8, 1.0/6.0));
+  priority_list = tree.GetPriorityList();
+  EXPECT_EQ(expected_list, priority_list);
+
+  // Remove a node from the tree to make sure priorities
+  // get redistributed accordingly.
+  EXPECT_TRUE(tree.RemoveNode(1));
+  expected_list.clear();
+  expected_list.push_back(PriorityNode(3, 30.0/51.0));
+  expected_list.push_back(PriorityNode(2, 20.0/51.0));
+  expected_list.push_back(PriorityNode(8, 1.0/51.0));
+  priority_list = tree.GetPriorityList();
+  EXPECT_EQ(expected_list, priority_list);
+
+  // Block an entire subtree.
+  EXPECT_TRUE(tree.SetReady(8, false));
+  expected_list.clear();
+  expected_list.push_back(PriorityNode(3, 0.6));
+  expected_list.push_back(PriorityNode(2, 0.4));
+  priority_list = tree.GetPriorityList();
+  EXPECT_EQ(expected_list, priority_list);
+
+  // Unblock previously blocked nodes.
+  EXPECT_TRUE(tree.SetReady(4, true));
+  EXPECT_TRUE(tree.SetReady(5, true));
+  expected_list.clear();
+  expected_list.push_back(PriorityNode(3, 1.0/2.0));
+  expected_list.push_back(PriorityNode(2, 1.0/3.0));
+  expected_list.push_back(PriorityNode(5, 9.0/60.0));
+  expected_list.push_back(PriorityNode(4, 1.0/60.0));
+  priority_list = tree.GetPriorityList();
+  EXPECT_EQ(expected_list, priority_list);
+
+  // Blocked nodes in multiple subtrees.
+  EXPECT_TRUE(tree.SetReady(2, false));
+  EXPECT_TRUE(tree.SetReady(6, false));
+  EXPECT_TRUE(tree.SetReady(7, false));
+  expected_list.clear();
+  expected_list.push_back(PriorityNode(3, 3.0/4.0));
+  expected_list.push_back(PriorityNode(5, 9.0/40.0));
+  expected_list.push_back(PriorityNode(4, 1.0/40.0));
+  priority_list = tree.GetPriorityList();
+  EXPECT_EQ(expected_list, priority_list);
+}
+
+TEST(SpdyPriorityTreeTest, CalculateRoundedWeights) {
+  typedef uint32 SpdyStreamId;
+  typedef std::pair<SpdyStreamId, float> PriorityNode;
+  typedef std::vector<PriorityNode> PriorityList;
+
+  PriorityList expected_list;
+  PriorityList priority_list;
+
+  /* Create the tree.
+
+           0
+          / \
+         1   2
+       //|\  |\
+      83 4 5 6 7
+  */
+  SpdyPriorityTree<uint32> tree;
+  tree.AddNode(3, 0, 100, false);
+  tree.AddNode(4, 0, 100, false);
+  tree.AddNode(5, 0, 100, false);
+  tree.AddNode(1, 0, 10, true);
+  tree.AddNode(2, 0, 5, false);
+  tree.AddNode(6, 2, 1, false);
+  tree.AddNode(7, 2, 1, false);
+  tree.AddNode(8, 1, 1, false);
+
+  // Remove higher-level nodes.
+  tree.RemoveNode(1);
+  tree.RemoveNode(2);
+
+  // 3.3 rounded down = 3.
+  EXPECT_EQ(3, tree.GetWeight(3));
+  EXPECT_EQ(3, tree.GetWeight(4));
+  EXPECT_EQ(3, tree.GetWeight(5));
+  // 2.5 rounded up = 3.
+  EXPECT_EQ(3, tree.GetWeight(6));
+  EXPECT_EQ(3, tree.GetWeight(7));
+  // 0 is not a valid weight, so round up to 1.
+  EXPECT_EQ(1, tree.GetWeight(8));
+}
+}  // namespace test
+}  // namespace gfe_spdy