From 1ca5e3cde6d0af8ac73e92b7066ddaf0067abf68 Mon Sep 17 00:00:00 2001
From: antao <antao2002@gmail.com>
Date: Tue, 26 Feb 2019 09:50:51 +0800
Subject: [PATCH] Use multiple database connections in the DbClientLockFree
 class

---
 orm_lib/src/DbClientLockFree.cc | 84 +++++++++++++++++++++------------
 orm_lib/src/DbClientLockFree.h  |  8 ++--
 2 files changed, 58 insertions(+), 34 deletions(-)

diff --git a/orm_lib/src/DbClientLockFree.cc b/orm_lib/src/DbClientLockFree.cc
index 2d35b51e..657ae6fd 100644
--- a/orm_lib/src/DbClientLockFree.cc
+++ b/orm_lib/src/DbClientLockFree.cc
@@ -47,13 +47,15 @@ DbClientLockFree::DbClientLockFree(const std::string &connInfo, trantor::EventLo
     if (type == ClientType::PostgreSQL)
     {
         _loop->runInLoop([this]() {
-            _connectionHolder = newConnection();
+            for (size_t i = 0; i < _connectionNum; i++)
+                _connectionHolders.push_back(newConnection());
         });
     }
     else if (type == ClientType::Mysql)
     {
         _loop->runInLoop([this]() {
-            _connectionHolder = newConnection();
+            for (size_t i = 0; i < _connectionNum; i++)
+                _connectionHolders.push_back(newConnection());
         });
     }
     else
@@ -64,9 +66,9 @@ DbClientLockFree::DbClientLockFree(const std::string &connInfo, trantor::EventLo
 
 DbClientLockFree::~DbClientLockFree() noexcept
 {
-    if (_connection)
+    for (auto &conn : _connections)
     {
-        _connection->disconnect();
+        conn->disconnect();
     }
 }
 
@@ -83,7 +85,7 @@ void DbClientLockFree::execSql(std::string &&sql,
     assert(paraNum == format.size());
     assert(rcb);
     _loop->assertInLoopThread();
-    if (!_connection)
+    if (_connections.empty())
     {
         try
         {
@@ -97,16 +99,19 @@ void DbClientLockFree::execSql(std::string &&sql,
     }
     else
     {
-        if (!_connection->isWorking())
+        for (auto &conn : _connections)
         {
-            _connection->execSql(std::move(sql),
-                                 paraNum,
-                                 std::move(parameters),
-                                 std::move(length),
-                                 std::move(format),
-                                 std::move(rcb),
-                                 std::move(exceptCallback));
-            return;
+            if (!conn->isWorking())
+            {
+                conn->execSql(std::move(sql),
+                              paraNum,
+                              std::move(parameters),
+                              std::move(length),
+                              std::move(format),
+                              std::move(rcb),
+                              std::move(exceptCallback));
+                return;
+            }
         }
     }
 
@@ -141,20 +146,20 @@ std::shared_ptr<Transaction> DbClientLockFree::newTransaction(const std::functio
     return nullptr;
 }
 
-void DbClientLockFree::handleNewTask()
+void DbClientLockFree::handleNewTask(const DbConnectionPtr &conn)
 {
-    assert(_connection);
-    assert(!_connection->isWorking());
+    assert(conn);
+    assert(!conn->isWorking());
     if (!_sqlCmdBuffer.empty())
     {
         auto &cmd = _sqlCmdBuffer.front();
-        _connection->execSql(std::move(cmd._sql),
-                             cmd._paraNum,
-                             std::move(cmd._parameters),
-                             std::move(cmd._length),
-                             std::move(cmd._format),
-                             std::move(cmd._cb),
-                             std::move(cmd._exceptCb));
+        conn->execSql(std::move(cmd._sql),
+                      cmd._paraNum,
+                      std::move(cmd._parameters),
+                      std::move(cmd._length),
+                      std::move(cmd._format),
+                      std::move(cmd._cb),
+                      std::move(cmd._exceptCb));
         _sqlCmdBuffer.pop_front();
         return;
     }
@@ -191,15 +196,29 @@ DbConnectionPtr DbClientLockFree::newConnection()
         if (!thisPtr)
             return;
 
-        assert(thisPtr->_connection);
-        thisPtr->_connection.reset();
+        for (auto iter = thisPtr->_connections.begin(); iter != thisPtr->_connections.end(); iter++)
+        {
+            if (closeConnPtr == *iter)
+            {
+                thisPtr->_connections.erase(iter);
+                break;
+            }
+        }
+        for (auto iter = thisPtr->_connectionHolders.begin(); iter != thisPtr->_connectionHolders.end(); iter++)
+        {
+            if (closeConnPtr == *iter)
+            {
+                thisPtr->_connectionHolders.erase(iter);
+                break;
+            }
+        }
 
         //Reconnect after 1 second
         thisPtr->_loop->runAfter(1, [weakPtr] {
             auto thisPtr = weakPtr.lock();
             if (!thisPtr)
                 return;
-            thisPtr->_connectionHolder = thisPtr->newConnection();
+            thisPtr->_connectionHolders.push_back(thisPtr->newConnection());
         });
     });
     connPtr->setOkCallback([weakPtr](const DbConnectionPtr &okConnPtr) {
@@ -207,14 +226,17 @@ DbConnectionPtr DbClientLockFree::newConnection()
         auto thisPtr = weakPtr.lock();
         if (!thisPtr)
             return;
-        thisPtr->_connection = okConnPtr;
-        thisPtr->handleNewTask();
+        thisPtr->_connections.push_back(okConnPtr);
+        thisPtr->handleNewTask(okConnPtr);
     });
-    connPtr->setIdleCallback([weakPtr]() {
+    std::weak_ptr<DbConnection> weakConnPtr = connPtr;
+    connPtr->setIdleCallback([weakPtr, weakConnPtr]() {
         auto thisPtr = weakPtr.lock();
         if (!thisPtr)
             return;
-        thisPtr->handleNewTask();
+        auto connPtr = weakConnPtr.lock();
+        assert(connPtr);
+        thisPtr->handleNewTask(connPtr);
     });
     //std::cout<<"newConn end"<<connPtr<<std::endl;
     return connPtr;
diff --git a/orm_lib/src/DbClientLockFree.h b/orm_lib/src/DbClientLockFree.h
index 326bc0ed..7a830f20 100644
--- a/orm_lib/src/DbClientLockFree.h
+++ b/orm_lib/src/DbClientLockFree.h
@@ -25,6 +25,7 @@
 #include <unordered_set>
 #include <list>
 
+
 namespace drogon
 {
 namespace orm
@@ -48,8 +49,9 @@ class DbClientLockFree : public DbClient, public std::enable_shared_from_this<Db
     std::string _connInfo;
     trantor::EventLoop *_loop;
     DbConnectionPtr newConnection();
-    DbConnectionPtr _connection;
-    DbConnectionPtr _connectionHolder;
+    const size_t _connectionNum = 4;
+    std::vector<DbConnectionPtr> _connections;
+    std::vector<DbConnectionPtr> _connectionHolders;
     struct SqlCmd
     {
         std::string _sql;
@@ -78,7 +80,7 @@ class DbClientLockFree : public DbClient, public std::enable_shared_from_this<Db
     };
     std::deque<SqlCmd> _sqlCmdBuffer;
 
-    void handleNewTask();
+    void handleNewTask(const DbConnectionPtr &conn);
 };
 
 } // namespace orm