finish basic design for BPT

.gitignore

@@ -3,4 +3,5 @@
 /.github
 /.cache
 /build
+/mbuild
 /.clang-format

bpt/include/bpt/bpt.hpp

@@ -1,25 +1,99 @@
 #ifndef BPT_HPP
 #define BPT_HPP
+#include <algorithm>
 #include <shared_mutex>
+#include <vector>
 #include "bpt/bpt_page.hpp"
 #include "bpt/buffer_pool_manager.h"
 #include "bpt/config.h"
+/**
+ * @brief B+ Tree Indexer
+ * @warning The KeyType must can be stored byte by byte. As this is only the indexer, the type of value is always
+ * b_plus_tree_value_index_t.
+ */
 template <typename KeyType, typename KeyComparator>
 class BPlusTreeIndexer {
- private:
+  typedef BPlusTreePage<KeyType> PageType;
-  // TODO : insert ?
+  typedef std::pair<KeyType, default_numeric_index_t> key_index_pair_t;
- public:
   typedef std::pair<KeyType, b_plus_tree_value_index_t> value_type;
+
+ private:
+  struct PositionSignType {
+    std::vector<std::pair<BasicPageGuard, in_page_key_count_t>> path;
+    bool is_end{false};
+  };
+  PositionSignType FindPosition(const KeyType &key) {  // Finish Design
+    if (root_page_id == 0) {
+      return PositionSignType{.is_end = true};
+    }
+    BasicPageGuard current_page_guard(bpm->FetchPageBasic(root_page_id));
+    static auto comparer_for_key_index_pair = [](const key_index_pair_t &a, const KeyType &b) {
+      return key_cmp(a.first, b);
+    };
+    in_page_key_count_t nxt = std::lower_bound(current_page_guard.As<PageType>()->data.p_data,
+                                               current_page_guard.As<PageType>()->data.p_data +
+                                                   current_page_guard.As<PageType>()->data.key_count,
+                                               key, comparer_for_key_index_pair) -
+                              current_page_guard.As<PageType>()->data.p_data;
+    PositionSignType res;
+    while (res.path.back().first.template As<PageType>()->data.page_status != 0) {
+      default_numeric_index_t nxt_page_id;
+      in_page_key_count_t internal_id = res.path.back().second;
+      if (internal_id < res.path.back().first.template As<PageType>()->data.key_count)
+        nxt_page_id = res.path.back().first.template As<PageType>()->data.p_data[internal_id].second;
+      else
+        nxt_page_id = res.path.back().first.template As<PageType>()->data.p_n;
+      BasicPageGuard next_page_guard(bpm->FetchPageBasic(nxt_page_id));
+      nxt =
+          std::lower_bound(next_page_guard.As<PageType>()->data.p_data,
+                           next_page_guard.As<PageType>()->data.p_data + next_page_guard.As<PageType>()->data.key_count,
+                           key, comparer_for_key_index_pair) -
+          next_page_guard.As<PageType>()->data.p_data;
+      res.path.push_back(std::make_pair(std::move(next_page_guard), nxt));
+    }
+    if (nxt == res.path.back().first.template As<PageType>()->data.key_count) res.is_end = true;
+    return res;
+  }
+  void InsertEntryAt(PositionSignType &pos, const KeyType &key, b_plus_tree_value_index_t value) {
+    // TODO
+  }
+  void RemoveEntryAt(PositionSignType &pos) {
+    // TODO
+  }
+
+ public:
+  // note that for safety, the iterator is not copyable, and the const_iterator is not copyable
   class iterator {
     BPlusTreeIndexer *domain;
     size_t internal_offset;
     bool is_end;
     WritePageGuard guard;
-    const KeyType &GetKey() const {
+    friend class BPlusTreeIndexer;
-      // TODO
+
+   public:
+    const KeyType &GetKey() const { return guard.As<PageType>()->data.p_data[internal_offset].first; }
+    const b_plus_tree_value_index_t &GetValue() { return guard.As<PageType>()->data.p_data[internal_offset].second; }
+    bool operator==(iterator &that) {
+      return domain == that.domain && guard.PageId() == that.guard.PageId() &&
+             internal_offset == that.internal_offset && is_end == that.is_end;
     }
-    const b_plus_tree_value_index_t &GetValue() const {
+    void SetValue(b_plus_tree_value_index_t new_value) {
-      // TODO
+      guard.AsMut<PageType>()->data.p_data[internal_offset].second = new_value;
+    }
+    // only support ++it
+    iterator &operator++() {
+      if (is_end) return *this;
+      internal_offset++;
+      if (internal_offset == guard.As<PageType>()->data.key_count) {
+        default_numeric_index_t nxt_page_id = guard.As<PageType>()->data.p_n;
+        if (nxt_page_id == 0) {
+          is_end = true;
+          return *this;
+        }
+        guard = domain->bpm->FetchPageWrite(nxt_page_id);
+        internal_offset = 0;
+      }
+      return *this;
     }
   };
   class const_iterator {
@@ -27,11 +101,29 @@ class BPlusTreeIndexer {
     size_t internal_offset;
     bool is_end;
     ReadPageGuard guard;
-    const KeyType &GetKey() const {
+    friend class BPlusTreeIndexer;
-      // TODO
+
+   public:
+    const KeyType &GetKey() { return guard.As<PageType>()->data.p_data[internal_offset].first; }
+    const b_plus_tree_value_index_t &GetValue() { return guard.As<PageType>()->data.p_data[internal_offset].second; }
+    bool operator==(const_iterator &that) {
+      return domain == that.domain && guard.PageId() == that.guard.PageId() &&
+             internal_offset == that.internal_offset && is_end == that.is_end;
     }
-    const b_plus_tree_value_index_t &GetValue() const {
+    // only support ++it
-      // TODO
+    const_iterator &operator++() {
+      if (is_end) return *this;
+      internal_offset++;
+      if (internal_offset == guard.As<PageType>()->data.key_count) {
+        default_numeric_index_t nxt_page_id = guard.As<PageType>()->data.p_n;
+        if (nxt_page_id == 0) {
+          is_end = true;
+          return *this;
+        }
+        guard = domain->bpm->FetchPageRead(nxt_page_id);
+        internal_offset = 0;
+      }
+      return *this;
     }
   };
   BPlusTreeIndexer() = delete;
@@ -39,61 +131,84 @@ class BPlusTreeIndexer {
   BPlusTreeIndexer(BPlusTreeIndexer &&) = delete;
   BPlusTreeIndexer &operator=(const BPlusTreeIndexer &) = delete;
   BPlusTreeIndexer &operator=(BPlusTreeIndexer &&) = delete;
-  iterator end() {
+  BPlusTreeIndexer(BufferPoolManager *bpm_) {
-    // TODO
+    bpm = bpm_;
+    raw_data_memory = bpm->RawDataMemory();
+    memcpy(&root_page_id, raw_data_memory, sizeof(page_id_t));
+    memcpy(&siz, raw_data_memory + sizeof(page_id_t), sizeof(bpt_size_t));
   }
-  iterator lower_bound(const KeyType &key) {
+  iterator end() { // Finish Design
+    iterator res;
+    res.domain = this;
+    res.is_end = true;
+    return res;
+  }
+  const_iterator end_const() { // Finish Design
+    const_iterator res;
+    res.domain = this;
+    res.is_end = true;
+    return res;
+  }
+  iterator lower_bound(const KeyType &key) {  // Finish Design
     std::shared_lock<std::shared_mutex> guard(latch);
-    // TODO
+    PositionSignType pos(std::move(FindPosition(key)));
+    iterator res;
+    res.domain = this;
+    res.guard = bpm->FetchPageWrite(pos.path.back().first.PageId());
+    res.is_end = pos.is_end;
+    res.internal_offset = pos.path.back().second;
+    return res;
   }
-  const_iterator lower_bound_const(const KeyType &key) {
+  const_iterator lower_bound_const(const KeyType &key) {  // Finish Design
     std::shared_lock<std::shared_mutex> guard(latch);
-    // TODO
+    PositionSignType pos(std::move(FindPosition(key)));
+    const_iterator res;
+    res.domain = this;
+    res.guard = bpm->FetchPageRead(pos.path.back().first.PageId());
+    res.is_end = pos.is_end;
+    res.internal_offset = pos.path.back().second;
+    return res;
   }
-  bool Set(const iterator &iter, b_plus_tree_value_index_t value) {
+  b_plus_tree_value_index_t Get(const KeyType &key) { // Finish Design
-    std::unique_lock<std::shared_mutex> guard(latch);
-    // TODO
-  }
-  bool Erase(const iterator &iter) {
-    std::unique_lock<std::shared_mutex> guard(latch);
-    // TODO
-  }
-  b_plus_tree_value_index_t Get(const KeyType &key) {
     auto it = lower_bound_const(key);
-    if (it == end()) return kInvalidValueIndex;
+    if (it == end_const()) return kInvalidValueIndex;
     if (key_cmp(key, it.GetKey())) return kInvalidValueIndex;
-    return it->second;
+    return it.GetValue();
   }
-  bool Put(const KeyType &key, b_plus_tree_value_index_t value) {
+  bool Put(const KeyType &key, b_plus_tree_value_index_t value) { // Finish Design
-    auto it = lower_bound(key);
+    PositionSignType pos(std::move(FindPosition(key)));
-    if (it != end() && !key_cmp(key, it.GetKey())) {
+    if (!pos.is_end &&
-      Set(it, value);
+        !key_cmp(key, pos.path.back().first.template As<PageType>()->data.p_data[pos.path.back().second].first)) {
+      pos.path.back().first.template AsMut<PageType>()->data.p_data[pos.path.back().second].second = value;
       return false;
     }
-    // TODO Insert it
+    InsertEntryAt(pos, key, value);
     return true;
   }
-  bool Remove(const KeyType &key) {
+  bool Remove(const KeyType &key) { // Finish Design
-    auto it = lower_bound(key);
+    PositionSignType pos(std::move(FindPosition(key)));
-    if (it == end()) return false;
+    if (pos.is_end) return false;
-    if (key_cmp(key, it.GetKey())) return false;
+    if (key_cmp(key, pos.path.back().first.template As<PageType>()->data.p_data[pos.path.back().second].first))
-    Erase(it);
+      return false;
+    RemoveEntryAt(pos);
     return true;
   }
-  size_t Size() { return siz; }
+  size_t Size() { return siz; }  // Finish Design
-  void Flush() {
+  void Flush() {                 // Finish Design
-    // TODO: do some recording
+    memcpy(raw_data_memory, &root_page_id, sizeof(page_id_t));
+    memcpy(raw_data_memory + sizeof(page_id_t), &siz, sizeof(bpt_size_t));
     bpm->FlushAllPages();
   }
 
  private:
   page_id_t root_page_id;  // stored in the first 4 (0-3) bytes of RawDatMemory, this directly operates on the buf
                            // maintained by DiskManager, BufferPoolManager only passes the pointer to it
-  uint64_t siz;            // stored in the next 8 (4-11) bytes of RawDatMemory, this directly operates on the buf
+  bpt_size_t siz;          // stored in the next 8 (4-11) bytes of RawDatMemory, this directly operates on the buf
                            // maintained by DiskManager, BufferPoolManager only passes the pointer to it
   static KeyComparator key_cmp;
   std::shared_mutex latch;
   BufferPoolManager *bpm;
+  char *raw_data_memory;
 };
 template <typename KeyType, typename KeyComparator>
 KeyComparator BPlusTreeIndexer<KeyType, KeyComparator>::key_cmp = KeyComparator();

bpt/include/bpt/bpt_page.hpp

@@ -6,12 +6,12 @@ template <typename KeyType, size_t kPageSize = 4096>
 struct ActualDataType {
   typedef std::pair<KeyType, default_numeric_index_t> value_type;
   page_id_t p_n;
-  page_id_t p_parent;
+  page_status_t page_status;  // root(2) / internal(1) / leaf(0)
-  uint8_t is_leaf;
+  in_page_key_count_t key_count;
-  uint16_t key_count;
   const static size_t kMaxKeyCount =
-      (kPageSize - sizeof(page_id_t) * 2 - sizeof(uint8_t) - sizeof(uint16_t)) / sizeof(value_type);
+      (kPageSize - sizeof(page_id_t) - sizeof(page_status_t) - sizeof(in_page_key_count_t)) / sizeof(value_type);
   value_type p_data[kMaxKeyCount];
+  static_assert(kMaxKeyCount >= 2, "kMaxKeyCount must be greater than or equal to 2");
 };
 template <typename KeyType, size_t kPageSize = 4096>
 union BPlusTreePage {

bpt/include/bpt/config.h

@@ -8,4 +8,7 @@ typedef default_numeric_index_t page_id_t;
 typedef default_numeric_index_t frame_id_t;
 typedef default_numeric_index_t b_plus_tree_value_index_t;
 extern const b_plus_tree_value_index_t kInvalidValueIndex;
+typedef uint8_t page_status_t;
+typedef uint16_t in_page_key_count_t;
+typedef uint64_t bpt_size_t;
 #endif

design.md

@@ -17,6 +17,12 @@
 - 一个火车票系统执行引擎
 - 一个直接的命令行交互系统，用于OJ测试/单会话模式/快照管理/数据错误检查
 - 一个Socket服务端，用于对接服务端
+
+## B+树
+基本参考：<https://en.wikipedia.org/wiki/B%2B_tree>
+- p[i]子树中的所有key K都满足： k[i-1] \< K \<= k[i]，且k[i]一定能取到，即直接无缝对接lower_bound
+- 对外接口提供类似于迭代器的东西，但该迭代器只支持向后单项移动、读取value值、修改value值，并且，迭代器会保留PageGuard，因此如果B+树在迭代器之前析构，会出现访问越界。
+
 # UI设计
 - 语言：Python
 - 与内核的交互：Socket

test/bpt_basic_test.cpp

@@ -1,7 +1,9 @@
 #include <gtest/gtest.h>
+#include <map>
 #include "bpt/bpt.hpp"
+#include "bpt/buffer_pool_manager.h"
 #include "bpt/config.h"
-
+#include "bpt/disk_manager.h"
 namespace bpt_basic_test {
 template <size_t length>
 class FixLengthString {
@@ -9,7 +11,7 @@ class FixLengthString {
   char data[length];
 };
 }  // namespace bpt_basic_test
-TEST(BasicTest, Compile) {
+TEST(BasicTest, Compile) {  // This Test only test the compile of the code
   // test for long long, int, char, long double
   BPlusTreePage<long long> page_long_long;
   static_assert(sizeof(page_long_long) == 4096, "BPlusTreePage size mismatch");
@@ -37,4 +39,17 @@ TEST(BasicTest, Compile) {
   static_assert(sizeof(page_35) == 4096, "BPlusTreePage size mismatch");
   BPlusTreePage<bpt_basic_test::FixLengthString<40>> page_40;
   static_assert(sizeof(page_40) == 4096, "BPlusTreePage size mismatch");
+
+  remove("/tmp/bpt1.db");
+  DiskManager *dm = new DiskManager("/tmp/bpt1.db");
+  BufferPoolManager *bpm = new BufferPoolManager(10, 3, dm);
+  BPlusTreeIndexer<long long, std::less<long long>> bpt(bpm);
+  auto it = bpt.lower_bound(1);
+  bpt.Flush();
+  bpt.Get(1);
+  it.SetValue(2);
+  bpt.Put(1, 2);
+  bpt.Remove(1);
+  delete bpm;
+  delete dm;
 }

test/buffer_pool_manager_test.cpp

@@ -177,7 +177,7 @@ TEST(StoreTest, Test1) {
   PageType c;
   c.data.p_n = 0x1f2f3f4f;
   c.data.key_count = 0x1f2a;
-  c.data.is_leaf = 0x3e;
+  c.data.page_status = 0x3e;
   c.data.p_data[17].first = 0x8f7f6f5f4f3f2f1f;
   c.filler[0] = 0x1f;
   *basic_guard.AsMut<PageType>() = c;
@@ -263,13 +263,13 @@ TEST(MemoryRiver, T2) {
   size_t interal_id_tot = 0;
   const unsigned int RndSeed = testing::GTEST_FLAG(random_seed);
   std::mt19937 rnd(RndSeed);
-  remove("/tmp/T2.std");
+  remove("T2.std");
-  remove("/tmp/T2.dat");
+  remove("T2.dat");
   const int kInfoLength = 100;
   {
     sol::MemoryRiver<DataType, kInfoLength> STD("/tmp/T2.std");
     MemoryRiver<DataType, kInfoLength> mr("/tmp/T2.dat");
-    int total_opts = 1000;
+    int total_opts = 1000000;
     while (total_opts-- > 0) {
       int opt = rnd() % 6;
       switch (opt) {