A NodeManager implementation with encoding/decoding keys/values into pages.

pkg/analysis_server/test/index/page_node_manager_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library test.index.page_node_manager;
+
+import 'dart:math';
+import 'dart:typed_data';
+
+import 'package:analysis_server/src/index/b_plus_tree.dart';
+import 'package:analysis_server/src/index/page_node_manager.dart';
+import 'package:unittest/unittest.dart';
+
+import '../reflective_tests.dart';
+
+
+main() {
+  groupSep = ' | ';
+  group('FixedStringCodecTest', () {
+    runReflectiveTests(_FixedStringCodecTest);
+  });
+  group('MemoryPageManager', () {
+    runReflectiveTests(_MemoryPageManagerTest);
+  });
+  group('PageNodeManager', () {
+    runReflectiveTests(_PageNodeManagerTest);
+  });
+  group('Uint32CodecTest', () {
+    runReflectiveTests(_Uint32CodecTest);
+  });
+  test('B+ tree with PageNodeManager', _treeWithPageNodeManager);
+}
+
+
+int _intComparator(int a, int b) => a - b;
+
+
+/**
+ * A stress test for [BPlusTree] using [PageNodeManager].
+ */
+_treeWithPageNodeManager() {
+  int pageSize = 256;
+  MemoryPageManager pageManager = new MemoryPageManager(pageSize);
+  NodeManager<int, String, int> nodeManager = new PageNodeManager<int, String>(
+      pageManager, Uint32Codec.INSTANCE, new FixedStringCodec(7));
+//  NodeManager<int, String, int> nodeManager = new MemoryNodeManager();
+  int maxIndexKeys = (pageSize - 64) ~/ (4 + 4);

[Paul Berry, 2014/06/10 18:39:09]

What's the source of the "- 64"?

[scheglov, 2014/06/10 20:12:12]

Already cleaned up.

+  int maxLeafKeys = (pageSize - 64) ~/ (4 + (2 + 2 * 7));
+  print('maxIndexKeys: $maxIndexKeys   maxLeafKeys: $maxLeafKeys');
+  BPlusTree<int, String, int> tree = new BPlusTree(maxIndexKeys, maxLeafKeys,
+      _intComparator, nodeManager);
+  int maxKey = 1000000;
+  int tryCount = 1000;
+  Set<int> keys = new Set<int>();
+  {
+    Random random = new Random();

[Paul Berry, 2014/06/10 18:39:08]

Using Random() makes the unit test nondeterministic, which makes it difficult to
debug.  I'd recommend seeding the random number generator with a constant, so
that if a test failure occurs, it will be reproducible.

[scheglov, 2014/06/10 20:12:12]

Done.

+    for (int i = 0; i < tryCount; i++) {
+      int key = random.nextInt(maxKey);
+      keys.add(key);
+      tree.insert(key, 'V$key');
+    }
+  }
+  // find every
+  for (int key in keys) {
+    expect(tree.find(key), 'V$key');
+  }
+  // remove random keys
+  {
+    Random random = new Random();
+    for (int key in new Set<int>.from(keys)) {
+      if (random.nextBool()) {
+        keys.remove(key);
+        expect(tree.remove(key), 'V$key');
+      }
+    }
+  }
+  // find every remaining key
+  for (int key in keys) {
+    expect(tree.find(key), 'V$key');
+  }
+}

[Paul Berry, 2014/06/10 18:39:08]

Should we also verify that all the removed keys are gone?

[scheglov, 2014/06/10 20:12:12]

Done.

+
+
+@ReflectiveTestCase()
+class _FixedStringCodecTest {
+  ByteData buffer;
+  Uint8List bytes = new Uint8List(2 + 2 * 4);
+  FixedStringCodec codec = new FixedStringCodec(4);
+
+  void setUp() {
+    buffer = new ByteData.view(bytes.buffer);
+  }
+
+  test_empty() {
+    // encode
+    codec.encode(buffer, '');
+    expect(bytes, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
+    // decode
+    expect(codec.decode(buffer), '');
+  }
+
+  test_fourChars() {
+    // encode
+    codec.encode(buffer, 'ABCD');
+    expect(bytes, [0, 4, 0, 65, 0, 66, 0, 67, 0, 68]);
+    // decode
+    expect(codec.decode(buffer), 'ABCD');
+  }
+
+  test_tooManyChars() {
+    expect(() {
+      codec.encode(buffer, 'ABCDE');
+    }, throws);
+  }
+
+  test_twoChars() {
+    // encode
+    codec.encode(buffer, 'AB');
+    expect(bytes, [0, 2, 0, 65, 0, 66, 0, 0, 0, 0]);
+    // decode
+    expect(codec.decode(buffer), 'AB');
+  }
+}

[Paul Berry, 2014/06/10 18:39:09]

We should also test:
- Non-ASCII characters
- Unicode code points beyond UTF-16

[scheglov, 2014/06/10 20:12:12]

IIRC Dart sources are UTF-8 encoded.
I've added some Russian string.

+
+
+
+@ReflectiveTestCase()
+class _MemoryPageManagerTest {
+  static const PAGE_SIZE = 8;
+  MemoryPageManager manager = new MemoryPageManager(PAGE_SIZE);
+
+  test_alloc() {
+    int idA = manager.alloc();
+    int idB = manager.alloc();
+    expect(idB, isNot(idA));
+  }
+
+  test_free() {
+    int id = manager.alloc();
+    manager.free(id);
+    // double free
+    expect(() {
+      manager.free(id);
+    }, throws);
+  }
+
+  test_read() {
+    int id = manager.alloc();
+    Uint8List page = manager.read(id);
+    expect(page.length, PAGE_SIZE);
+  }
+
+  test_read_doesNotExist() {
+    expect(() {
+      manager.read(0);
+    }, throws);
+  }
+
+  test_write() {
+    int id = manager.alloc();
+    // do write
+    {
+      Uint8List page = new Uint8List(PAGE_SIZE);
+      page[3] = 42;
+      manager.write(id, page);
+    }
+    // now read
+    {
+      Uint8List page = manager.read(id);
+      expect(page.length, PAGE_SIZE);
+      expect(page[3], 42);
+    }
+  }
+
+  test_write_doesNotExist() {
+    expect(() {
+      Uint8List page = new Uint8List(PAGE_SIZE);
+      manager.write(42, page);
+    }, throws);
+  }
+}
+
+
+
+@ReflectiveTestCase()
+class _PageNodeManagerTest {
+  static const Codec KEY_CODEC = Uint32Codec.INSTANCE;
+  static const int PAGE_SIZE = 128;
+  static const Codec VALUE_CODEC = const FixedStringCodec(4);
+
+  PageNodeManager<int, String> nodeManager;
+  MemoryPageManager pageManager = new MemoryPageManager(PAGE_SIZE);
+
+  setUp() {
+    nodeManager = new PageNodeManager<int, String>(pageManager, KEY_CODEC,
+        VALUE_CODEC);
+  }
+
+  test_index_createDelete() {
+    int id = nodeManager.createIndex();
+    expect(nodeManager.isIndex(id), isTrue);
+    // do delete
+    nodeManager.delete(id);
+    expect(nodeManager.isIndex(id), isFalse);
+  }
+
+  test_index_readWrite() {
+    int id = nodeManager.createIndex();
+    expect(nodeManager.isIndex(id), isTrue);
+    // write
+    {
+      var keys = [1, 2];
+      var children = [10, 20, 30];
+      nodeManager.writeIndex(id, new IndexNodeData<int, int>(keys, children));
+    }
+    // check the page
+    {
+      Uint8List page = pageManager.read(id);
+      expect(page, [0, 0, 0, 2, 0, 0, 0, 10, 0, 0, 0, 1, 0, 0, 0, 20, 0, 0, 0,
+          2, 0, 0, 0, 30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+          0, 0]);
+    }
+    // read
+    {
+      IndexNodeData<int, int> data = nodeManager.readIndex(id);
+      expect(data.keys, [1, 2]);
+      expect(data.children, [10, 20, 30]);
+    }
+  }
+
+  test_leaf_readWrite() {
+    int id = nodeManager.createLeaf();
+    expect(nodeManager.isIndex(id), isFalse);
+    // write
+    {
+      var keys = [1, 2, 3];
+      var children = ['A', 'BB', 'CCC'];
+      nodeManager.writeLeaf(id, new LeafNodeData<int, String>(keys, children));
+    }
+    // check the page
+    {
+      Uint8List page = pageManager.read(id);
+      expect(page, [0, 0, 0, 3, 0, 0, 0, 1, 0, 1, 0, 65, 0, 0, 0, 0, 0, 0, 0, 0,
+          0, 2, 0, 2, 0, 66, 0, 66, 0, 0, 0, 0, 0, 0, 0, 3, 0, 3, 0, 67, 0, 67, 0, 67, 0,
+          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+          0, 0]);
+    }
+    // read
+    {
+      LeafNodeData<int, String> data = nodeManager.readLeaf(id);
+      expect(data.keys, [1, 2, 3]);
+      expect(data.values, ['A', 'BB', 'CCC']);
+    }
+  }
+}
+
+@ReflectiveTestCase()
+class _Uint32CodecTest {
+  ByteData buffer;
+  Uint8List bytes = new Uint8List(4);
+  Uint32Codec codec = Uint32Codec.INSTANCE;
+
+  void setUp() {
+    buffer = new ByteData.view(bytes.buffer);
+  }
+
+  test_all() {
+    // encode
+    codec.encode(buffer, 42);
+    expect(bytes, [0, 0, 0, 42]);
+    // decode
+    expect(codec.decode(buffer), 42);
+  }
+}