From 8d45bf108bfe8f41b339591598737b54c4eb5799 Mon Sep 17 00:00:00 2001
From: xxy <3237539022@qq.com>
Date: Fri, 6 Dec 2024 11:11:29 +0800
Subject: [PATCH] v3 roughly complete while mutex lacks in put

---
 CMakeLists.txt            |   2 +-
 db/db_impl.cc             | 322 +++++++++++++++++++++++-----------------------
 db/db_impl.h              |   7 +
 include/leveldb/options.h |   3 +
 test/test.cpp             |   6 +-
 5 files changed, 174 insertions(+), 166 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 99951c3..122df31 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,7 @@ project(leveldb VERSION 1.23.0 LANGUAGES C CXX)
 if(NOT CMAKE_C_STANDARD)
   # This project can use C11, but will gracefully decay down to C89.
   # 我改到17了
-  set(CMAKE_C_STANDARD 11)
+  set(CMAKE_C_STANDARD 17)
   set(CMAKE_C_STANDARD_REQUIRED OFF)
   set(CMAKE_C_EXTENSIONS OFF)
 endif(NOT CMAKE_C_STANDARD)
diff --git a/db/db_impl.cc b/db/db_impl.cc
index 231e29c..27f8560 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -20,6 +20,7 @@
 #include <cstdio>
 
 #include <fstream>
+#include <thread>
 #include <iostream>
 #include <set>
 #include <string>
@@ -142,6 +143,7 @@ DBImpl::DBImpl(const Options& raw_options, const std::string& dbname)
       db_lock_(nullptr),
       shutting_down_(false),
       background_work_finished_signal_(&mutex_),
+      background_gc_finished_signal_(&gc_mutex_),
       mem_(nullptr),
       imm_(nullptr),
       has_imm_(false),
@@ -668,8 +670,9 @@ void DBImpl::TEST_GarbageCollect() {
   // Finish current background compaction in the case where
   // `background_work_finished_signal_` was signalled due to an error.
   while (background_garbage_collect_scheduled_) {
-    background_work_finished_signal_.Wait();
+    background_gc_finished_signal_.Wait();
   }
+  // std::cout<<"bg_signal"<<std::endl;
 }
 
 void DBImpl::RecordBackgroundError(const Status& s) {
@@ -707,10 +710,11 @@ void DBImpl::MaybeScheduleGarbageCollect() {
   } else if (!bg_error_.ok()) {
     // Already got an error; no more changes
   } else {
+    gc_mutex_.Lock();
     background_garbage_collect_scheduled_ = true;
-    env_->Schedule(&DBImpl::BGWorkGC, this);
+    auto bg_thread_ = std::thread(&DBImpl::BGWorkGC, this);
+    bg_thread_.detach();
   }
-
 }
 
 void DBImpl::BGWorkGC(void* db) {
@@ -744,7 +748,7 @@ void DBImpl::BackgroundCall() {
 }
 
 void DBImpl::BackgroundGarbageCollect() {
-  mutex_.AssertHeld();
+  MutexLock l(&gc_mutex_);
   assert(background_garbage_collect_scheduled_);
 
   if (shutting_down_.load(std::memory_order_acquire)) {
@@ -754,12 +758,15 @@ void DBImpl::BackgroundGarbageCollect() {
   } else {
     // Perform garbage collection here
     GarbageCollect();
+    gc_mutex_.Unlock();
+
   }
 
   background_garbage_collect_scheduled_ = false;
 
   // Notify any waiting threads
-  background_work_finished_signal_.SignalAll();
+  background_gc_finished_signal_.SignalAll();
+
 }
 
 void DBImpl::BackgroundCompaction() {
@@ -1219,6 +1226,10 @@ Status DBImpl::Get(const ReadOptions& options, const Slice& key,
   mem->Unref();
   if (imm != nullptr) imm->Unref();
   current->Unref();
+  if(!s.ok())return s;
+  if(options.find_value_log_for_gc){
+    return s;
+  }
 
   if (value->c_str()[0] == 0x00) {
     *value = value->substr(1);
@@ -1233,7 +1244,10 @@ Status DBImpl::Get(const ReadOptions& options, const Slice& key,
   if (!res) return Status::Corruption("can't decode file id");
   res = GetVarint64(&value_log_slice, &valuelog_offset);
   if (!res) return Status::Corruption("can't decode valuelog offset");
-  ReadValueLog(file_id, valuelog_offset, &new_key, &new_value);
+  s=ReadValueLog(file_id, valuelog_offset, &new_key, &new_value);
+  if(!s.ok()){
+    return s;
+  }
   *value = std::string(new_value.data(), new_value.size());
   delete[] new_value.data();
   return s;
@@ -1787,8 +1801,9 @@ bool IsValueLogFile(const std::string& filename) {
 void ParseStoredValue(const std::string& stored_value, uint64_t& valuelog_id,
                       uint64_t& offset) {
   // 假设 stored_value 格式为：valuelog_id|offset
-  std::istringstream iss(stored_value);
-  iss >> valuelog_id >> offset;
+  Slice tmp(stored_value.data(),stored_value.size());
+  GetVarint64(&tmp,&valuelog_id);
+  GetVarint64(&tmp,&offset);
 }
 
 // 示例：获取 ValueLog 文件 ID
@@ -1818,184 +1833,167 @@ uint64_t GetValueLogID(const std::string& valuelog_name) {
 
 // 垃圾回收实现
 void DBImpl::GarbageCollect() {
+  gc_mutex_.AssertHeld();
   // 遍历数据库目录，找到所有 valuelog 文件
   Log(options_.info_log, "start gc ");
   auto files_set = fs::directory_iterator(dbname_);
+  std::set<std::string> valuelog_set;
+  std::string cur_valuelog_name=ValueLogFileName(dbname_,valuelogfile_number_);
   for (const auto& cur_log_file : files_set) {
     if (fs::exists(cur_log_file) &&
-        fs::is_regular_file(fs::status(cur_log_file)) &&
-        IsValueLogFile(cur_log_file.path().filename().string())) {
-      std::string valuelog_name = cur_log_file.path().string();
-      std::cout << valuelog_name << std::endl;
-      uint64_t cur_log_number = GetValueLogID(valuelog_name);
-      std::cout << "check point 1" << std::endl;
-      uint64_t new_log_number = versions_->NewFileNumber();
-      WritableFile* new_valuelog = nullptr;
-      std::string new_valuelog_name = LogFileName(dbname_, new_log_number);
-      Status s = env_->NewWritableFile(LogFileName(dbname_, new_log_number),
-                                       &new_valuelog);
-      if (!s.ok()) {
-        // Avoid chewing through file number space in a tight loop.
-        versions_->ReuseFileNumber(new_log_number);
-        break;
-      }
-      addNewValueLog();
-      std::cout << "check point 2" << std::endl;
-
-      // whether to reopen
-      std::ifstream new_valuelog_file(new_valuelog_name,
-                                      std::ios::in | std::ios::binary);
-      if (!new_valuelog_file.is_open()) {
-        std::cerr << "Failed to create new ValueLog file: " << new_valuelog_name
-                  << std::endl;
-        continue;
-      }
-
-      uint64_t current_offset = 0;
-      uint64_t tmp_offset = 0;
+    fs::is_regular_file(fs::status(cur_log_file)) &&
+    IsValueLogFile(cur_log_file.path().filename().string())) {
+      if(cur_valuelog_name==cur_log_file.path().filename().string())continue;
+      valuelog_set.emplace(cur_log_file.path().filename().string()); 
+    }
+  }
+  for (std::string valuelog_name:valuelog_set) {
+    // std::cout << valuelog_name << std::endl;
+    uint64_t cur_log_number = GetValueLogID(valuelog_name);
+    valuelog_name=ValueLogFileName(dbname_,cur_log_number);
 
-      int cnt=0;
+    uint64_t current_offset = 0;
+    uint64_t tmp_offset = 0;
 
-      std::cout << "check point 3" << std::endl;
+    int cnt=0;
 
-    // Open the file in binary mode for reading
-      std::ifstream cur_valuelog(valuelog_name, std::ios::in | std::ios::binary);
-      if (!cur_valuelog.is_open()) {
-        std::cerr << "Failed to open file: " << valuelog_name << " for reading cur_valuelog!"
-                  << std::endl;
-        continue;
-      }
-
-      while (true) {
-        tmp_offset=current_offset;
-        ++cnt;
-        std::cout << cnt <<"   "<<current_offset<< std::endl;
-        
-
-        // 读取一个 kv 对
-        uint64_t key_len, value_len;
-        Slice key, value;
+  // Open the file in binary mode for reading
+    std::ifstream cur_valuelog(valuelog_name, std::ios::in | std::ios::binary);
+    if (!cur_valuelog.is_open()) {
+      std::cerr << "Failed to open file: " << valuelog_name << " for reading cur_valuelog!"
+                << std::endl;
+      continue;
+    }
 
-        Status s = Status::OK();
+    while (true) {
+      tmp_offset=current_offset;
+      ++cnt;
+      // std::cout << cnt <<"   "<<current_offset<< std::endl;
+      
+      // 读取一个 kv 对
+      uint64_t key_len, value_len;
+      Slice key, value;
 
-         // Seek to the position of key length
-        cur_valuelog.seekg(current_offset);
+      Status s = Status::OK();
 
-        // Read the length of the key
-        char* key_buf_len = new char[sizeof(uint64_t)];
-        cur_valuelog.read(key_buf_len, sizeof(uint64_t));
+        // Seek to the position of key length
+      cur_valuelog.seekg(current_offset);
 
-        if (cur_valuelog.eof()) {
-          delete[] key_buf_len;
-          break; // 正常退出条件：到达文件末尾
-        }
+      // Read the length of the key
+      char* key_buf_len = new char[sizeof(uint64_t)];
+      cur_valuelog.read(key_buf_len, sizeof(uint64_t));
 
-        std::memcpy(&key_len, key_buf_len, sizeof(uint64_t));
+      if (cur_valuelog.eof()) {
+        delete[] key_buf_len;
+        break; // 正常退出条件：到达文件末尾
+      }
 
-        if (!cur_valuelog.good()) {
-          delete[] key_buf_len;
-          cur_valuelog.close();
-          std::cerr << "Failed to read file: " << valuelog_name << std::endl;
-          break;
-        }
-        // 更新当前偏移
-        current_offset += sizeof(uint64_t);
-
-        // Now seek to the actual key position and read the key
-        cur_valuelog.seekg(current_offset);
-        char* key_buf = new char[key_len];
-        cur_valuelog.read(key_buf, key_len);
-        if (!cur_valuelog.good()) {
-          delete[] key_buf;
-          delete[] key_buf_len;
-          cur_valuelog.close();
-          std::cerr << "Failed to read file: " << valuelog_name << std::endl;
-          break;
-        }
-        current_offset += key_len;
-        
-
-        // Assign the read key data to the Slice
-        key = Slice(key_buf, key_len);
-
-        // Read the length of the value
-        cur_valuelog.seekg(current_offset);
-        char* value_buf_len = new char[sizeof(uint64_t)];
-        cur_valuelog.read(value_buf_len, sizeof(uint64_t));
-        uint64_t val_len = 0;
-        std::memcpy(&val_len, value_buf_len, sizeof(uint64_t));
-
-        if (!cur_valuelog.good()) {
-          delete[] key_buf;
-          delete[] key_buf_len;
-          delete[] value_buf_len;
-          cur_valuelog.close();
-          std::cerr << "Failed to read file: " << valuelog_name << std::endl;
-          break;
-        }
-        // 更新当前偏移
-        current_offset += sizeof(uint64_t);
-
-        // Now seek to the actual data position and read the value
-        cur_valuelog.seekg(current_offset);
-        char* value_buf = new char[val_len];
-        cur_valuelog.read(value_buf, val_len);
-        if (!cur_valuelog.good()) {
-          delete[] key_buf;
-          delete[] key_buf_len;
-          delete[] value_buf_len;
-          delete[] value_buf;
-          cur_valuelog.close();
-          std::cerr << "Failed to read file: " << valuelog_name << std::endl;
-          break;
-        }
-        current_offset += val_len;
+      std::memcpy(&key_len, key_buf_len, sizeof(uint64_t));
 
-        // Assign the read value data to the Slice
-        value = Slice(value_buf, val_len);
+      if (!cur_valuelog.good()) {
+        delete[] key_buf_len;
+        cur_valuelog.close();
+        std::cerr << "Failed to read file: " << valuelog_name << std::endl;
+        break;
+      }
+      // 更新当前偏移
+      current_offset += sizeof(uint64_t);
+
+      // Now seek to the actual key position and read the key
+      cur_valuelog.seekg(current_offset);
+      char* key_buf = new char[key_len];
+      cur_valuelog.read(key_buf, key_len);
+      if (!cur_valuelog.good()) {
+        delete[] key_buf;
+        delete[] key_buf_len;
+        cur_valuelog.close();
+        std::cerr << "Failed to read file: " << valuelog_name << std::endl;
+        break;
+      }
+      current_offset += key_len;
+      
+
+      // Assign the read key data to the Slice
+      key = Slice(key_buf, key_len);
+
+      // Read the length of the value
+      cur_valuelog.seekg(current_offset);
+      char* value_buf_len = new char[sizeof(uint64_t)];
+      cur_valuelog.read(value_buf_len, sizeof(uint64_t));
+      uint64_t val_len = 0;
+      std::memcpy(&val_len, value_buf_len, sizeof(uint64_t));
+
+      if (!cur_valuelog.good()) {
+        delete[] key_buf;
+        delete[] key_buf_len;
+        delete[] value_buf_len;
+        cur_valuelog.close();
+        std::cerr << "Failed to read file: " << valuelog_name << std::endl;
+        break;
+      }
+      // 更新当前偏移
+      current_offset += sizeof(uint64_t);
+
+      // Now seek to the actual data position and read the value
+      cur_valuelog.seekg(current_offset);
+      char* value_buf = new char[val_len];
+      cur_valuelog.read(value_buf, val_len);
+      if (!cur_valuelog.good()) {
+        delete[] key_buf;
+        delete[] key_buf_len;
+        delete[] value_buf_len;
+        delete[] value_buf;
+        cur_valuelog.close();
+        std::cerr << "Failed to read file: " << valuelog_name << std::endl;
+        break;
+      }
+      current_offset += val_len;
 
-        // 检查 key 是否在 sstable 中存在
-        std::string stored_value;
-        Status status = Get(leveldb::ReadOptions(), key, &stored_value);
+      // Assign the read value data to the Slice
+      value = Slice(value_buf, val_len);
+      // std::cout<<val_len<<std::endl;
 
-        if (status.IsNotFound()) {
-          // Key 不存在，忽略此记录
-          continue;
-        }
+      // 检查 key 是否在 sstable 中存在
+      std::string stored_value;
+      auto option=leveldb::ReadOptions();
+      option.find_value_log_for_gc = true;
 
-        if (!status.ok()) {
-          std::cerr << "Error accessing sstable: " << status.ToString()
-                    << std::endl;
-          continue;
-        }
+      Status status = Get(option, key, &stored_value);
 
-        // 检查 valuelog_id 和 offset 是否匹配
-        uint64_t stored_valuelog_id, stored_offset;
-        ParseStoredValue(stored_value, stored_valuelog_id,
-                         stored_offset);  // 假设解析函数
-        if (stored_valuelog_id != GetValueLogID(valuelog_name) ||
-            stored_offset != tmp_offset) {
-          // 记录无效，跳过
-          continue;
-        }
+      if (status.IsNotFound()) {
+        // Key 不存在，忽略此记录
+        continue;
+      }
 
-        status = Put(leveldb::WriteOptions(), key, value);
-        if (!status.ok()) {
-          std::cerr << "Error accessing sstable: " << status.ToString()
-                    << std::endl;
-          continue;
-        }
+      if (!status.ok()) {
+        std::cerr << "Error accessing sstable: " << status.ToString()
+                  << std::endl;
+        continue;
       }
 
-      // 清理旧文件（如果需要）
-      cur_valuelog.close();
-      new_valuelog_file.close();
+      // 检查 valuelog_id 和 offset 是否匹配
+      uint64_t stored_valuelog_id, stored_offset;
+      ParseStoredValue(stored_value.substr(1), stored_valuelog_id,
+                        stored_offset);  // 假设解析函数
+      if (stored_valuelog_id != GetValueLogID(valuelog_name) ||
+          stored_offset != tmp_offset) {
+        // 记录无效，跳过
+        continue;
+      }
+  
+      status = Put(leveldb::WriteOptions(), key, value);
+      if (!status.ok()) {
+        std::cerr << "Error accessing sstable: " << status.ToString()
+                  << std::endl;
+        continue;
+      }
+    }
 
-      std::remove(valuelog_name.c_str());  // 删除旧的 ValueLog 文件
-      Log(options_.info_log, "remove file during gc %s", valuelog_name.c_str());
-      Log(options_.info_log, "add file during gc %s", new_valuelog_name.c_str());
+    // 清理旧文件（如果需要）
+    cur_valuelog.close();
 
-    }
+    std::remove(valuelog_name.c_str());  // 删除旧的 ValueLog 文件
+    Log(options_.info_log, "remove file during gc %s", valuelog_name.c_str());
   }
 }
 
diff --git a/db/db_impl.h b/db/db_impl.h
index 0f44458..530690b 100644
--- a/db/db_impl.h
+++ b/db/db_impl.h
@@ -210,9 +210,16 @@ class DBImpl : public DB {
 
   // State below is protected by mutex_
   port::Mutex mutex_;
+  port::Mutex gc_mutex_;
+  // port::Mutex spj_mutex_;
+
   // std::shared_mutex value_log_mutex;
   std::atomic<bool> shutting_down_;
   port::CondVar background_work_finished_signal_ GUARDED_BY(mutex_);
+  port::CondVar background_gc_finished_signal_ GUARDED_BY(gc_mutex_);
+
+  // Slice valuelog_finding_key GUARDED_BY(mutex_ );
+
   MemTable* mem_;
   MemTable* imm_ GUARDED_BY(mutex_);  // Memtable being compacted
   std::atomic<bool> has_imm_;         // So bg thread can detect non-null imm_
diff --git a/include/leveldb/options.h b/include/leveldb/options.h
index d755f46..cad5032 100644
--- a/include/leveldb/options.h
+++ b/include/leveldb/options.h
@@ -157,6 +157,8 @@ struct LEVELDB_EXPORT ReadOptions {
   // Callers may wish to set this field to false for bulk scans.
   bool fill_cache = true;
 
+  bool find_value_log_for_gc = false;
+
   // If "snapshot" is non-null, read as of the supplied snapshot
   // (which must belong to the DB that is being read and which must
   // not have been released).  If "snapshot" is null, use an implicit
@@ -183,6 +185,7 @@ struct LEVELDB_EXPORT WriteOptions {
   // with sync==true has similar crash semantics to a "write()"
   // system call followed by "fsync()".
   bool sync = false;
+  // bool valuelog_write=false;
 };
 
 }  // namespace leveldb
diff --git a/test/test.cpp b/test/test.cpp
index 2b7ac95..077e947 100644
--- a/test/test.cpp
+++ b/test/test.cpp
@@ -199,7 +199,7 @@ TEST(Test, Garbage_Collect_TEST) {
         abort();
     }
     std::vector<std::string> values;
-    for(int i=0;i<5000;i++){
+    for(int i=0;i<500000;i++){
         std::string key=std::to_string(i);
         std::string value;
         for(int j=0;j<1000;j++){
@@ -212,8 +212,8 @@ TEST(Test, Garbage_Collect_TEST) {
     db->TEST_GarbageCollect();
     std::cout<<"finish gc"<<std::endl;
 
-    for(int i=0;i<5000;i++){
-        std::cout<<i<<std::endl;
+    for(int i=0;i<500000;i++){
+        // std::cout<<i<<std::endl;
         std::string key=std::to_string(i);
         std::string value;
         Status s=db->Get(readOptions,key,&value);