Make the number of the connections of Fast DB Clients configurable

config.example.json

@@ -47,7 +47,8 @@
             //is_fast: false by default, if it is true, the client is faster but user can't call
             //any synchronous interface of it.
             "is_fast": false,
-            //connection_number: 1 by default, valid only if is_fast is false.
+            //connection_number: 1 by default, if the 'is_fast' is true, the number is the number of  
+            connections per IO thread, otherwise it is the total number of all connections.  
             "connection_number": 1
         }
     ],*/

drogon_ctl/templates/config.csp

@@ -47,7 +47,8 @@
             //is_fast: false by default, if it is true, the client is faster but user can't call
             //any synchronous interface of it.
             "is_fast": false,
-            //connection_number: 1 by default, valid only if is_fast is false.
+            //connection_number: 1 by default, if the 'is_fast' is true, the number is the number of  
+            connections per IO thread, otherwise it is the total number of all connections.  
             "connection_number": 1
         }
     ],*/

lib/src/HttpAppFrameworkImpl.cc

@@ -521,7 +521,10 @@ void HttpAppFrameworkImpl::createDbClients(
                     _dbFastClientsMap[dbInfo._name][loop] =
                         std::shared_ptr<drogon::orm::DbClient>(
                             new drogon::orm::DbClientLockFree(
-                                dbInfo._connectionInfo, loop, dbInfo._dbType));
+                                dbInfo._connectionInfo,
+                                loop,
+                                dbInfo._dbType,
+                                dbInfo._connectionNumber));
                 }
             }
         }

orm_lib/src/DbClientLockFree.cc

@@ -41,8 +41,9 @@ using namespace drogon::orm;
 
 DbClientLockFree::DbClientLockFree(const std::string &connInfo,
                                    trantor::EventLoop *loop,
-                                   ClientType type)
-    : _connInfo(connInfo), _loop(loop)
+                                   ClientType type,
+                                   size_t connectionNumberPerLoop)
+    : _connInfo(connInfo), _loop(loop), _connectionNum(connectionNumberPerLoop)
 {
     _type = type;
     LOG_TRACE << "type=" << (int)type;

orm_lib/src/DbClientLockFree.h

@@ -35,7 +35,8 @@ class DbClientLockFree : public DbClient,
   public:
     DbClientLockFree(const std::string &connInfo,
                      trantor::EventLoop *loop,
-                     ClientType type);
+                     ClientType type,
+                     size_t connectionNumberPerLoop);
     virtual ~DbClientLockFree() noexcept;
     virtual void execSql(std::string &&sql,
                          size_t paraNum,
@@ -55,7 +56,7 @@ class DbClientLockFree : public DbClient,
     std::string _connInfo;
     trantor::EventLoop *_loop;
     DbConnectionPtr newConnection();
-    const size_t _connectionNum = 4;
+    const size_t _connectionNum;
     std::vector<DbConnectionPtr> _connections;
     std::vector<DbConnectionPtr> _connectionHolders;
     std::unordered_set<DbConnectionPtr> _transSet;