bugfix：persist相关设计 (#56)

youngyangyang04 · Apr 7, 2024 · 412718d · 412718d
1 parent 987cd54
commit 412718d
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Showing 2 changed files with 85 additions and 24 deletions.
diff --git a/src/raftCore/Persister.cpp b/src/raftCore/Persister.cpp
@@ -3,25 +3,26 @@
 //
 #include "Persister.h"
 #include "util.h"
-// todo:如果文件出现问题会怎么办？？
+
+// todo:会涉及反复打开文件的操作，没有考虑如果文件出现问题会怎么办？？
 void Persister::Save(const std::string raftstate, const std::string snapshot) {
-  std::lock_guard<std::mutex> lg(mtx);
+  std::lock_guard<std::mutex> lg(m_mtx);
+  clearRaftStateAndSnapshot();
   // 将raftstate和snapshot写入本地文件
-  std::ofstream outfile;
   m_raftStateOutStream << raftstate;
   m_snapshotOutStream << snapshot;
 }
 
 std::string Persister::ReadSnapshot() {
-  std::lock_guard<std::mutex> lg(mtx);
+  std::lock_guard<std::mutex> lg(m_mtx);
   if (m_snapshotOutStream.is_open()) {
     m_snapshotOutStream.close();
   }
-  //    Defer ec1([this]()-> void {
-  //        this->m_snapshotOutStream.open(snapshotFile);
-  //    }); //这个变量后生成，会先销毁
-  DEFER { m_snapshotOutStream.open(snapshotFile); };  //这个变量后生成，会先销毁
-  std::fstream ifs(snapshotFile, std::ios_base::in);
+
+  DEFER {
+    m_snapshotOutStream.open(m_snapshotFileName);  //默认是追加
+  };
+  std::fstream ifs(m_snapshotFileName, std::ios_base::in);
   if (!ifs.good()) {
     return "";
   }
@@ -32,21 +33,23 @@ std::string Persister::ReadSnapshot() {
 }
 
 void Persister::SaveRaftState(const std::string &data) {
-  std::lock_guard<std::mutex> lg(mtx);
+  std::lock_guard<std::mutex> lg(m_mtx);
   // 将raftstate和snapshot写入本地文件
+  clearRaftState();
   m_raftStateOutStream << data;
+  m_raftStateSize += data.size();
 }
 
 long long Persister::RaftStateSize() {
-  std::lock_guard<std::mutex> lg(mtx);
+  std::lock_guard<std::mutex> lg(m_mtx);
 
   return m_raftStateSize;
 }
 
 std::string Persister::ReadRaftState() {
-  std::lock_guard<std::mutex> lg(mtx);
+  std::lock_guard<std::mutex> lg(m_mtx);
 
-  std::fstream ifs(raftStateFile, std::ios_base::in);
+  std::fstream ifs(m_raftStateFileName, std::ios_base::in);
   if (!ifs.good()) {
     return "";
   }
@@ -56,20 +59,34 @@ std::string Persister::ReadRaftState() {
   return snapshot;
 }
 
-Persister::Persister(int me)
-    : raftStateFile("raftstatePersist" + std::to_string(me) + ".txt"),
-      snapshotFile("snapshotPersist" + std::to_string(me) + ".txt"),
+Persister::Persister(const int me)
+    : m_raftStateFileName("raftstatePersist" + std::to_string(me) + ".txt"),
+      m_snapshotFileName("snapshotPersist" + std::to_string(me) + ".txt"),
       m_raftStateSize(0) {
-  std::fstream file(raftStateFile, std::ios::out | std::ios::trunc);
+  /**
+   * 检查文件状态并清空文件
+   */
+  bool fileOpenFlag = true;
+  std::fstream file(m_raftStateFileName, std::ios::out | std::ios::trunc);
   if (file.is_open()) {
     file.close();
+  } else {
+    fileOpenFlag = false;
   }
-  file = std::fstream(snapshotFile, std::ios::out | std::ios::trunc);
+  file = std::fstream(m_snapshotFileName, std::ios::out | std::ios::trunc);
   if (file.is_open()) {
     file.close();
+  } else {
+    fileOpenFlag = false;
   }
-  m_raftStateOutStream.open(raftStateFile);
-  m_snapshotOutStream.open(snapshotFile);
+  if (!fileOpenFlag) {
+    DPrintf("[func-Persister::Persister] file open error");
+  }
+  /**
+   * 绑定流
+   */
+  m_raftStateOutStream.open(m_raftStateFileName);
+  m_snapshotOutStream.open(m_snapshotFileName);
 }
 
 Persister::~Persister() {
@@ -80,3 +97,25 @@ Persister::~Persister() {
     m_snapshotOutStream.close();
   }
 }
+
+void Persister::clearRaftState() {
+  m_raftStateSize = 0;
+  // 关闭文件流
+  if (m_raftStateOutStream.is_open()) {
+    m_raftStateOutStream.close();
+  }
+  // 重新打开文件流并清空文件内容
+  m_raftStateOutStream.open(m_raftStateFileName, std::ios::out | std::ios::trunc);
+}
+
+void Persister::clearSnapshot() {
+  if (m_snapshotOutStream.is_open()) {
+    m_snapshotOutStream.close();
+  }
+  m_snapshotOutStream.open(m_snapshotFileName, std::ios::out | std::ios::trunc);
+}
+
+void Persister::clearRaftStateAndSnapshot() {
+  clearRaftState();
+  clearSnapshot();
+}
diff --git a/src/raftCore/include/Persister.h b/src/raftCore/include/Persister.h
@@ -8,14 +8,31 @@
 #include <mutex>
 class Persister {
  private:
-  std::mutex mtx;
+  std::mutex m_mtx;
   std::string m_raftState;
   std::string m_snapshot;
-  const std::string raftStateFile;
-  const std::string snapshotFile;
+  /**
+   * m_raftStateFileName: raftState文件名
+   */
+  const std::string m_raftStateFileName;
+  /**
+   * m_snapshotFileName: snapshot文件名
+   */
+  const std::string m_snapshotFileName;
+  /**
+   * 保存raftState的输出流
+   */
   std::ofstream m_raftStateOutStream;
+  /**
+   * 保存snapshot的输出流
+   */
   std::ofstream m_snapshotOutStream;
-  long long m_raftStateSize;  //避免每次都读取文件的具体大小
+  /**
+   * 保存raftStateSize的大小
+   * 避免每次都读取文件来获取具体的大小
+   */
+  long long m_raftStateSize;
+
  public:
   void Save(std::string raftstate, std::string snapshot);
   std::string ReadSnapshot();
@@ -24,6 +41,11 @@ class Persister {
   std::string ReadRaftState();
   explicit Persister(int me);
   ~Persister();
+
+ private:
+  void clearRaftState();
+  void clearSnapshot();
+  void clearRaftStateAndSnapshot();
 };
 
 #endif  // SKIP_LIST_ON_RAFT_PERSISTER_H