Add methods to get DbClient connection status (#436)

lib/inc/drogon/HttpAppFramework.h

@@ -1013,6 +1013,11 @@ class HttpAppFramework : public trantor::NonCopyable
      */
     virtual orm::DbClientPtr getFastDbClient(
         const std::string &name = "default") = 0;
+    /**
+     * @brief Check if all database clients in the framework are available
+     * (connect to the database successfully).
+     */
+    virtual bool areAllDbClientsAvailable() const noexcept = 0;
 
     /// Create a database client
     /**

lib/src/DbClientManager.h

@@ -52,6 +52,7 @@ class DbClientManager : public trantor::NonCopyable
                         const std::string &filename,
                         const std::string &name,
                         const bool isFast);
+    bool areAllDbClientsAvailable() const noexcept;
 
   private:
     std::map<std::string, DbClientPtr> dbClientsMap_;

lib/src/DbClientManagerSkipped.cc

@@ -37,6 +37,13 @@ void DbClientManager::createDbClient(const std::string &dbType,
                                      const std::string &filename,
                                      const std::string &name,
                                      const bool isFast)
+{
+    LOG_FATAL << "No database is supported by drogon, please install the "
+                 "database development library first.";
+    abort();
+}
+
+bool DbClientManager::areAllDbClientsAvailable() const noexcept
 {
     LOG_FATAL << "No database is supported by drogon, please install the "
                  "database development library first.";

lib/src/HttpAppFrameworkImpl.cc

@@ -328,7 +328,7 @@ HttpAppFramework &HttpAppFrameworkImpl::setLogPath(
     if (access(logPath.c_str(), 0) != 0)
 #endif
     {
-        std::cerr << "Log path dose not exist!\n";
+        std::cerr << "Log path does not exist!\n";
         exit(1);
     }
 #ifdef _WIN32
@@ -943,3 +943,8 @@ HttpAppFramework &HttpAppFrameworkImpl::addALocation(
                                        filters);
     return *this;
 }
+
+bool HttpAppFrameworkImpl::areAllDbClientsAvailable() const noexcept
+{
+    return dbClientManagerPtr_->areAllDbClientsAvailable();
+}

lib/src/HttpAppFrameworkImpl.h

@@ -432,6 +432,8 @@ class HttpAppFrameworkImpl : public HttpAppFramework
 #endif
     }
 
+    virtual bool areAllDbClientsAvailable() const noexcept override;
+
   private:
     virtual void registerHttpController(
         const std::string &pathPattern,

orm_lib/inc/drogon/orm/DbClient.h

@@ -181,6 +181,13 @@ class DbClient : public trantor::NonCopyable
     virtual void newTransactionAsync(
         const std::function<void(const std::shared_ptr<Transaction> &)>
             &callback) = 0;
+    /**
+     * @brief Check if there is a connection successfully established.
+     *
+     * @return true
+     * @return false
+     */
+    virtual bool hasAvailableConnections() const noexcept = 0;
 
     ClientType type() const
     {

orm_lib/src/DbClientImpl.cc

@@ -440,3 +440,9 @@ DbConnectionPtr DbClientImpl::newConnection(trantor::EventLoop *loop)
     // std::cout<<"newConn end"<<connPtr<<std::endl;
     return connPtr;
 }
+
+bool DbClientImpl::hasAvailableConnections() const noexcept
+{
+    std::lock_guard<std::mutex> lock(connectionsMutex_);
+    return (!readyConnections_.empty()) || (!busyConnections_.empty());
+}

orm_lib/src/DbClientImpl.h

@@ -50,6 +50,7 @@ class DbClientImpl : public DbClient,
     virtual void newTransactionAsync(
         const std::function<void(const std::shared_ptr<Transaction> &)>
             &callback) override;
+    virtual bool hasAvailableConnections() const noexcept override;
 
   private:
     size_t connectionsNumber_;
@@ -72,7 +73,7 @@ class DbClientImpl : public DbClient,
         const DbConnectionPtr &conn,
         std::function<void(const std::shared_ptr<Transaction> &)> &&callback);
 
-    std::mutex connectionsMutex_;
+    mutable std::mutex connectionsMutex_;
     std::unordered_set<DbConnectionPtr> connections_;
     std::unordered_set<DbConnectionPtr> readyConnections_;
     std::unordered_set<DbConnectionPtr> busyConnections_;

orm_lib/src/DbClientLockFree.cc

@@ -434,3 +434,8 @@ DbConnectionPtr DbClientLockFree::newConnection()
     // std::cout<<"newConn end"<<connPtr<<std::endl;
     return connPtr;
 }
+
+bool DbClientLockFree::hasAvailableConnections() const noexcept
+{
+    return !connections_.empty();
+}

orm_lib/src/DbClientLockFree.h

@@ -51,6 +51,7 @@ class DbClientLockFree : public DbClient,
     virtual void newTransactionAsync(
         const std::function<void(const std::shared_ptr<Transaction> &)>
             &callback) override;
+    virtual bool hasAvailableConnections() const noexcept override;
 
   private:
     std::string connectionInfo_;

orm_lib/src/DbClientManager.cc

@@ -155,3 +155,22 @@ void DbClientManager::createDbClient(const std::string &dbType,
 #endif
     }
 }
+
+bool DbClientManager::areAllDbClientsAvailable() const noexcept
+{
+    for (auto const &pair : dbClientsMap_)
+    {
+        if (!(pair.second)->hasAvailableConnections())
+            return false;
+    }
+    auto loop = trantor::EventLoop::getEventLoopOfCurrentThread();
+    if (loop && loop->index() < app().getThreadNum())
+    {
+        for (auto const &pair : dbFastClientsMap_)
+        {
+            if (!(*(pair.second))->hasAvailableConnections())
+                return false;
+        }
+    }
+    return true;
+}

orm_lib/src/TransactionImpl.h

@@ -38,6 +38,10 @@ class TransactionImpl : public Transaction,
     {
         commitCallback_ = commitCallback;
     }
+    virtual bool hasAvailableConnections() const noexcept override
+    {
+        return connectionPtr_->status() == ConnectStatus::Ok;
+    }
 
   private:
     DbConnectionPtr connectionPtr_;

orm_lib/tests/db_test.cc

@@ -1937,13 +1937,25 @@ int main(int argc, char *argv[])
 #if USE_POSTGRESQL
     auto postgre_client = DbClient::newPgClient(
         "host=127.0.0.1 port=5432 dbname=postgres user=postgres", 1);
+    while (!postgre_client->hasAvailableConnections())
+    {
+        std::this_thread::sleep_for(1s);
+    }
 #endif
 #if USE_MYSQL
     auto mysql_client =
         DbClient::newMysqlClient("host=localhost port=3306 user=root", 1);
+    while (!mysql_client->hasAvailableConnections())
+    {
+        std::this_thread::sleep_for(1s);
+    }
 #endif
 #if USE_SQLITE3
     auto sqlite_client = DbClient::newSqlite3Client("filename=:memory:", 1);
+    while (!sqlite_client->hasAvailableConnections())
+    {
+        std::this_thread::sleep_for(1s);
+    }
 #endif
     LOG_DEBUG << "start!";
     std::this_thread::sleep_for(1s);