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diff --git a/src/lib/database/database_connection.h b/src/lib/database/database_connection.h
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+// Copyright (C) 2015-2022 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef DATABASE_CONNECTION_H
+#define DATABASE_CONNECTION_H
+
+#include <asiolink/io_service.h>
+#include <cc/data.h>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <exceptions/exceptions.h>
+#include <util/reconnect_ctl.h>
+#include <functional>
+#include <map>
+#include <string>
+
+namespace isc {
+namespace db {
+
+/// @brief Exception thrown if name of database is not specified
+class NoDatabaseName : public Exception {
+public:
+    NoDatabaseName(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+/// @brief Exception thrown on failure to open database
+class DbOpenError : public Exception {
+public:
+    DbOpenError(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+/// @brief Exception thrown on failure to execute a database function
+class DbOperationError : public Exception {
+public:
+    DbOperationError(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+/// @brief Exception thrown when a specific connection has been rendered unusable
+/// either through loss of connectivity or API lib error
+class DbConnectionUnusable : public Exception {
+public:
+    DbConnectionUnusable(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+
+/// @brief Invalid type exception
+///
+/// Thrown when the factory doesn't recognize the type of the backend.
+class InvalidType : public Exception {
+public:
+    InvalidType(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+/// @brief Invalid Timeout
+///
+/// Thrown when the timeout specified for the database connection is invalid.
+class DbInvalidTimeout : public Exception {
+public:
+    DbInvalidTimeout(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+/// @brief Invalid 'readonly' value specification.
+///
+/// Thrown when the value of the 'readonly' boolean parameter is invalid.
+class DbInvalidReadOnly : public Exception {
+public:
+    DbInvalidReadOnly(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) {}
+};
+
+/// @brief Defines a callback prototype for propagating events upward
+typedef std::function<bool (util::ReconnectCtlPtr db_reconnect_ctl)> DbCallback;
+
+/// @brief Function which returns the IOService that can be used to recover the
+/// connection.
+///
+/// This accessor is used to lazy retrieve the IOService when the connection is
+/// lost. It is useful to retrieve it at a later time to support hook libraries
+/// which create managers on load and set IOService later on by using the
+/// dhcp4_srv_configured and dhcp6_srv_configured hooks.
+typedef std::function<isc::asiolink::IOServicePtr ()> IOServiceAccessor;
+
+/// @brief Pointer to an instance of IOServiceAccessor
+typedef boost::shared_ptr<IOServiceAccessor> IOServiceAccessorPtr;
+
+/// @brief Common database connection class.
+///
+/// This class provides functions that are common for establishing
+/// connection with different types of databases; enables operations
+/// on access parameters strings. In particular, it provides a way
+/// to parse parameters in key=value format. This class is expected
+/// to be a base class for all @ref isc::dhcp::LeaseMgr and possibly
+/// @ref isc::dhcp::BaseHostDataSource derived classes.
+class DatabaseConnection : public boost::noncopyable {
+public:
+
+    /// @brief Defines maximum value for time that can be reliably stored.
+    ///
+    /// @todo: Is this common for MySQL and Postgres? Maybe we should have
+    /// specific values for each backend?
+    ///
+    /// If I'm still alive I'll be too old to care. You fix it.
+    static const time_t MAX_DB_TIME;
+
+    /// @brief Database configuration parameter map
+    typedef std::map<std::string, std::string> ParameterMap;
+
+    /// @brief Constructor
+    ///
+    /// @param parameters A data structure relating keywords and values
+    ///        concerned with the database.
+    /// @param callback The connection recovery callback.
+    DatabaseConnection(const ParameterMap& parameters,
+                       DbCallback callback = DbCallback())
+        : parameters_(parameters), callback_(callback), unusable_(false) {
+    }
+
+    /// @brief Destructor
+    virtual ~DatabaseConnection(){};
+
+    /// @brief Instantiates a ReconnectCtl based on the connection's
+    /// reconnect parameters
+    ///
+    /// @param timer_name of the timer used for the ReconnectCtl object.
+    virtual void makeReconnectCtl(const std::string& timer_name);
+
+    /// @brief The reconnect settings.
+    ///
+    /// @return The reconnect settings.
+    util::ReconnectCtlPtr reconnectCtl() {
+        return (reconnect_ctl_);
+    }
+
+    /// @brief Returns value of a connection parameter.
+    ///
+    /// @param name Name of the parameter which value should be returned.
+    /// @return Value of one of the connection parameters.
+    /// @throw BadValue if parameter is not found
+    std::string getParameter(const std::string& name) const;
+
+    /// @brief Parse database access string
+    ///
+    /// Parses the string of "keyword=value" pairs and separates them
+    /// out into the map. A value of the password parameter may include
+    /// whitespace in which case it must be surrounded by apostrophes.
+    ///
+    /// @param dbaccess Database access string.
+    ///
+    /// @return @ref ParameterMap of keyword/value pairs.
+    static ParameterMap parse(const std::string& dbaccess);
+
+    /// @brief Redact database access string
+    ///
+    /// Takes the database parameters and returns a database access string
+    /// passwords replaced by asterisks. This string is used in log messages.
+    ///
+    /// @param parameters Database access parameters (output of "parse").
+    ///
+    /// @return Redacted database access string.
+    static std::string redactedAccessString(const ParameterMap& parameters);
+
+    /// @brief Convenience method checking if database should be opened with
+    /// read only access.
+    ///
+    /// @return true if "readonly" parameter is specified and set to true;
+    /// false if "readonly" parameter is not specified or it is specified
+    /// and set to false.
+    bool configuredReadOnly() const;
+
+    /// @brief Invokes the connection's lost connectivity callback
+    ///
+    /// @return Returns the result of the callback or false if there is no
+    /// callback.
+    static bool invokeDbLostCallback(const util::ReconnectCtlPtr& db_reconnect_ctl);
+
+    /// @brief Invokes the connection's restored connectivity callback
+    ///
+    /// @return Returns the result of the callback or false if there is no
+    /// callback.
+    static bool invokeDbRecoveredCallback(const util::ReconnectCtlPtr& db_reconnect_ctl);
+
+    /// @brief Invokes the connection's restore failed connectivity callback
+    ///
+    /// @return Returns the result of the callback or false if there is no
+    /// callback.
+    static bool invokeDbFailedCallback(const util::ReconnectCtlPtr& db_reconnect_ctl);
+
+    /// @brief Unparse a parameter map
+    ///
+    /// @param params the parameter map to unparse
+    /// @return a pointer to configuration
+    static isc::data::ElementPtr toElement(const ParameterMap& params);
+
+    /// @brief Unparse an access string
+    ///
+    /// @param dbaccess the database access string
+    /// @return a pointer to configuration
+    static isc::data::ElementPtr toElementDbAccessString(const std::string& dbaccess);
+
+    /// @brief Optional callback function to invoke if an opened connection is
+    /// lost
+    static DbCallback db_lost_callback_;
+
+    /// @brief Optional callback function to invoke if an opened connection
+    /// recovery succeeded
+    static DbCallback db_recovered_callback_;
+
+    /// @brief Optional callback function to invoke if an opened connection
+    /// recovery failed
+    static DbCallback db_failed_callback_;
+
+    /// @brief Throws an exception if the connection is not usable.
+    /// @throw DbConnectionUnusable
+    void checkUnusable() {
+        if (unusable_)  {
+            isc_throw (DbConnectionUnusable, "Attempt to use an invalid connection");
+        }
+    }
+
+    /// @brief Flag which indicates if connection is unusable.
+    ///
+    /// @return true if the connection is unusable, false otherwise
+    bool isUnusable() {
+        return (unusable_);
+    }
+
+protected:
+    /// @brief Sets the unusable flag to true.
+    void markUnusable() { unusable_ = true; }
+
+private:
+
+    /// @brief List of parameters passed in dbconfig
+    ///
+    /// That will be mostly used for storing database name, username,
+    /// password and other parameters required for DB access. It is not
+    /// intended to keep any DHCP-related parameters.
+    ParameterMap parameters_;
+
+protected:
+
+    /// @brief The callback used to recover the connection.
+    DbCallback callback_;
+
+private:
+
+    /// @brief Indicates if the connection can no longer be used for normal
+    /// operations. Typically a connection is marked unusable after an unrecoverable
+    /// DB error. There may be a time when the connection exists, after
+    /// such an event, during which it cannot be used for anything beyond checking
+    /// parameters and error information. This flag can be used as a guard in
+    /// code to prevent inadvertent use of a broken connection.
+    bool unusable_;
+
+    /// @brief Reconnect settings.
+    util::ReconnectCtlPtr reconnect_ctl_;
+};
+
+}  // namespace db
+}  // namespace isc
+
+#endif // DATABASE_CONNECTION_H