From 6f3b895d51e5cf3ff94fafe31e2dfb23fcfb2d1b Mon Sep 17 00:00:00 2001
From: wym <1057857414@qq.com>
Date: Sat, 24 Jun 2023 22:28:06 -0700
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E4=B8=80=E4=BA=9B=E6=B3=A8?=
 =?UTF-8?q?=E9=87=8A=EF=BC=8C=E5=9C=A8Rmfilehandle=E4=B8=AD=E5=A3=B0?=
 =?UTF-8?q?=E6=98=8E=E5=8F=8B=E7=B1=BBSeqRecScan,=E5=AE=8C=E6=88=90?=
 =?UTF-8?q?=E4=BA=86executor=E4=B8=AD=E7=9A=84=E9=A1=BA=E5=BA=8F=E6=89=AB?=
 =?UTF-8?q?=E6=8F=8F?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/execution/executor_seq_scan.h | 159 ++++++++++++++++++++++++++++--
 src/record/rm_file_handle.h       |   3 +-
 src/record/rm_scan.cpp            |   1 +
 3 files changed, 156 insertions(+), 7 deletions(-)

diff --git a/src/execution/executor_seq_scan.h b/src/execution/executor_seq_scan.h
index d50912b..0f23ccc 100755
--- a/src/execution/executor_seq_scan.h
+++ b/src/execution/executor_seq_scan.h
@@ -16,6 +16,84 @@ See the Mulan PSL v2 for more details. */
 #include "index/ix.h"
 #include "system/sm.h"
 
+class SeqRecScan : public RecScan {
+private:
+    // 其他成员变量和方法
+    const RmFileHandle *file_handle_;
+    Rid rid_;
+public:
+    SeqRecScan(RmFileHandle *fh_) : file_handle_(fh_) {
+        // Todo:
+	    // 初始化file_handle和rid（指向第一个存放了记录的位置）
+        rid_={1,-1};
+        int start_page=rid_.page_no;
+        int start_slot=rid_.slot_no;
+        for(int i = start_page; i < file_handle_->file_hdr_.num_pages; i++){
+            RmPageHandle page_handle = file_handle_->fetch_page_handle(i);
+            if (page_handle.page_hdr->num_records != 0) {
+                rid_ = {i, Bitmap::next_bit(true, page_handle.bitmap, page_handle.file_hdr->num_records_per_page, -1)};
+                file_handle_->buffer_pool_manager_->unpin_page(page_handle.page->get_page_id(), false);
+                return;
+            }
+        }
+        rid_ = {file_handle_->file_hdr_.num_pages, -1};
+        return;
+    }
+
+    void next() override {
+        // 实现获取下一个记录的逻辑
+        // Todo:
+	    // 找到文件中下一个存放了记录的非空闲位置，用rid_来指向这个位置
+
+	    //设置一个标志位来指示是在当前页还是下一页搜寻
+	    bool flag = false;
+	    // 当前槽位为 -1（表示结束或初始状态），则无需继续执行，函数直接返回
+	    if (rid_.slot_no == -1) {
+		    return;
+	    }
+	    int max_pages_num=file_handle_->file_hdr_.num_pages;
+
+	    //for循环扫描
+	    for (int i = rid_.page_no; i < max_pages_num; i++) {
+		    RmPageHandle page_handle = file_handle_->fetch_page_handle(i);
+
+            if (page_handle.page_hdr->num_records != 0) {
+                int slot_no = Bitmap::next_bit(true, page_handle.bitmap, page_handle.file_hdr->num_records_per_page, flag ? -1 : rid_.slot_no);
+                int page_end=page_handle.file_hdr->num_records_per_page;
+                //next_bit扫描到了页面末尾仍未找到1位,进入下一次for循环扫描下一页
+                if (slot_no == page_end) {
+                    rid_.slot_no = -1;
+                    continue;
+                }
+                //nextbit找到了1位
+                else{
+                    rid_ = {i, slot_no};
+                    file_handle_->buffer_pool_manager_->unpin_page(page_handle.page->get_page_id(), false);
+                    return;
+                }
+            }
+            //unpin
+            file_handle_->buffer_pool_manager_->unpin_page(page_handle.page->get_page_id(), false);
+            //置标志位为1，从本页的slotno而不是-1开始寻找
+            flag = true;
+	    }
+	    rid_ = {max_pages_num, -1};
+	    return;
+    }
+
+    bool is_end() const override {
+        // 实现判断是否到达记录集的末尾的逻辑
+        return rid_.slot_no == -1;
+    }
+
+    Rid rid() const override {
+        // 返回当前记录的 RID
+        return rid_;
+    }
+};
+
+
+
 class SeqScanExecutor : public AbstractExecutor {
    private:
     std::string tab_name_;              // 表的名称
@@ -26,9 +104,10 @@ class SeqScanExecutor : public AbstractExecutor {
     std::vector<Condition> fed_conds_;  // 同conds_，两个字段相同
 
     Rid rid_;
-    std::unique_ptr<RecScan> scan_;     // table_iterator
+    std::unique_ptr<SeqRecScan> scan_;     // table_iterator
 
     SmManager *sm_manager_;
+    std::vector<ColMeta> cols_check_;         // 条件语句中所有用到列的列的元数据信息
 
    public:
     SeqScanExecutor(SmManager *sm_manager, std::string tab_name, std::vector<Condition> conds, Context *context) {
@@ -39,22 +118,90 @@ class SeqScanExecutor : public AbstractExecutor {
         fh_ = sm_manager_->fhs_.at(tab_name_).get();
         cols_ = tab.cols;
         len_ = cols_.back().offset + cols_.back().len;
-
+        //hashmap
+        std::unordered_map<std::string, ColMeta> ColName_to_ColMeta_=tab.ColName_to_ColMeta;
         context_ = context;
 
-        fed_conds_ = conds_;
+        fed_conds_ = conds_;//后续查询优化可以从fedcond入手!!!!!!!!!!!!!!!!!!!
+
+        //初始化条件语句中所有用到列的列的元数据信息
+        int i=0;
+        for (const auto& condition : fed_conds_) {
+
+            // 检查左操作数是否为列操作数
+            if (!condition.lhs_col.tab_name.empty() && !condition.lhs_col.col_name.empty()) {
+                // 查找colmeta
+                ColMeta temp=ColName_to_ColMeta_[condition.lhs_col.col_name];
+                // 将元数据对象添加到列的元数据向量中
+                cols_check_.push_back(temp);
+        }
+
+            // 检查右操作数是否为列操作数
+            if (!condition.is_rhs_val && !condition.rhs_col.tab_name.empty() && !condition.rhs_col.col_name.empty()) {
+                // 查找colmeta
+                ColMeta temp=ColName_to_ColMeta_[condition.rhs_col.col_name];
+                // 将元数据对象添加到列的元数据向量中
+                cols_check_.push_back(temp);
+            }
+        }
     }
 
     void beginTuple() override {
-        
+        // 初始化执行器的状态，准备开始遍历记录
+        // 这个函数在第一次调用 Next() 前会被自动调用
+        // 可以在这里进行一些初始化操作
+    
+        // 初始化记录迭代器
+        scan_ = std::make_unique<SeqRecScan>(fh_);
+        // 设置初始 RID
+        rid_ = scan_->rid();
+
     }
 
     void nextTuple() override {
-        
+        scan_->next();
+        rid_=scan_->rid();
     }
 
     std::unique_ptr<RmRecord> Next() override {
-        return nullptr;
+
+        //-1表明为空或到达了末尾
+        if(rid_.slot_no==-1){
+            return nullptr;
+        }
+
+        //设置标志位，表示是否找到符合条件record
+        bool found=false;
+
+        //进入循环，寻找到符合条件的record就返回，否则继续取下一条record
+        for(;!scan_->is_end();nextTuple()){
+
+            //取出当前记录
+            auto record_for_check = fh_->get_record(rid_,nullptr);
+
+            //标志位，表达式是否为true
+            bool right=false;
+
+            //依次判断所有condition
+            int right_num=0;
+            int should_right=fed_conds_.size();
+            for (const auto& condition : fed_conds_) {
+                if(!ConditionEvaluator::evaluate(condition,cols_check_,*record_for_check)){
+
+                    //一旦有一个condition为false就终止求条件表达式值 break,然后进入外部的continue，取下一条记录
+                    break;
+                }
+
+                //该条条件语句为true，计数器加一
+                right_num++;
+                
+                //所有条件语句都true,返回该条记录
+                if(right_num==should_right){
+                    return record_for_check;
+                }
+            }
+            continue;
+        }
     }
 
     Rid &rid() override { return rid_; }
diff --git a/src/record/rm_file_handle.h b/src/record/rm_file_handle.h
index 541aa8d..567deb8 100644
--- a/src/record/rm_file_handle.h
+++ b/src/record/rm_file_handle.h
@@ -42,7 +42,8 @@ struct RmPageHandle {
 
 /* 每个RmFileHandle对应一个表的数据文件，里面有多个page，每个page的数据封装在RmPageHandle中 */
 class RmFileHandle {      
-    friend class RmScan;    
+    friend class RmScan; 
+    friend class SeqRecScan;   
     friend class RmManager;
 
    private:
diff --git a/src/record/rm_scan.cpp b/src/record/rm_scan.cpp
index 17d15eb..1d8beef 100644
--- a/src/record/rm_scan.cpp
+++ b/src/record/rm_scan.cpp
@@ -22,6 +22,7 @@ RmScan::RmScan(const RmFileHandle *file_handle) : file_handle_(file_handle) {
     rid_={1,-1};
     int start_page=rid_.page_no;
     int start_slot=rid_.slot_no;
+	//从第一页的-1号位开始遍历
     for(int i = start_page; i < file_handle_->file_hdr_.num_pages; i++){
         auto page_handle = file_handle_->fetch_page_handle(i);
 		if (page_handle.page_hdr->num_records != 0) {
-- 
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